Magnetic resonance imaging (MRI) is a widely used method for non-invasive study of the structure and function of the human brain. Increasing magnetic field strengths enable higher resolution imaging; ...however, long scan times and high motion sensitivity mean that image quality is often limited by the involuntary motion of the subject. Prospective motion correction is a technique that addresses this problem by tracking head motion and continuously updating the imaging pulse sequence, locking the imaging volume position and orientation relative to the moving brain. The accuracy and precision of current MR-compatible tracking systems and navigator methods allows the quantification and correction of large-scale motion, but not the correction of very small involuntary movements in six degrees of freedom. In this work, we present an MR-compatible tracking system comprising a single camera and a single 15 mm marker that provides tracking precision in the order of 10 m and 0.01 degrees. We show preliminary results, which indicate that when used for prospective motion correction, the system enables improvement in image quality at both 3 T and 7 T, even in experienced and cooperative subjects trained to remain motionless during imaging. We also report direct observation and quantification of the mechanical ballistocardiogram (BCG) during simultaneous MR imaging. This is particularly apparent in the head-feet direction, with a peak-to-peak displacement of 140 m.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract Background A key to understanding potential anterior cruciate ligament injury mechanisms is to determine joint loading characteristics associated with an injury-causing event. However, ...direct measurement of anterior cruciate ligament loading during athletic tasks is invasive. Thus, previous research has been unable to study the association between neuromuscular variables and anterior cruciate ligament loading. Therefore, the purpose of this study was to determine the influence of movement anticipation on anterior cruciate ligament loading using a musculoskeletal modeling approach. Methods Twenty healthy recreationally active females were recruited to perform anticipated and unanticipated sidestep cutting. Three-dimensional kinematics and kinetics of the right leg were calculated. Muscle, joint and anterior cruciate ligament forces were then estimated using a musculoskeletal model. Dependent t-tests were conducted to investigate differences between the two cutting conditions. Findings ACL loading significantly increased during unanticipated sidestep cutting (p < 0.05). This increase was primarily due to a significant increase in the sagittal plane ACL loading, which contributed 62% of the total loading. Frontal plane ACL loading contributed 26% and transverse plane ACL loading contributed 12%. Interpretation These results suggest that anterior cruciate ligament loading resulted from a multifaceted interaction of the sagittal plane shear forces (i.e., quadriceps, hamstrings, and tibiofemoral), as well as the frontal and transverse plane knee moments. Additionally, the results of this study confirm the hypothesis in the current literature that unanticipated movements such as sidestep cutting increase anterior cruciate ligament loading.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The shape and size of particles are understood to affect the bulk behaviour of powders, though there are but few studies that present quantitative information on the relationship between particle ...shape and the flow properties of powder. This is due in part to the lack of techniques for rapidly determining both particle shape and the range of flow characteristics that describe the response of powders to the stress and shear experienced during their processing. This study presents data that quantifies the influence of particle shapeJsize of three different lactose powders on their respective flow and bulk characteristics. Two of the samples differ in size but have similar shapes; the third sample is more spherical but similar in size to one of the other two samples, The results demonstrate that in addition to particle size, particle shape significantly affect the flow characteristics of a powder over a wide range of stress conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
PURPOSETo investigate the effects of an exhaustive run on trunk and lower extremity strength and mechanics in patients with and without patellofemoral pain (PFP), we hypothesized that strength would ...decrease and mechanics would change after the exhaustive run.
METHODSNineteen subjects with PFP and 19 controls participated (10 men and 9 women per group). Lower extremity and trunk mechanics during running, body mass–normalized strength, and pain assessments before and after an exhaustive run were quantified. A repeated-measures ANOVA was used to assess group differences and exhaustion-related changes (P < 0.05), with t-test post hoc analyses performed when significant interactions were identified (P < 0.0125).
RESULTSPain significantly increased with the exhaustive run in the PFP group (P = 0.021). Hip strength was reduced after the exhaustive run, more so in those with PFP (abductionbefore = 0.384 ± 0.08, after = 0.314 ± 0.08, P < 0.001; external rotationbefore = 0.113 ± 0.02, after = 0.090 ± 0.02, P < 0.001). Persons with PFP also demonstrated increased knee flexion (before = 41.6° ± 5.5°, after = 46.9° ± 7.5°, P < 0.001), hip flexion (before = 30.4° ± 6.8°, after = 42.5° ± 9.7°, P < 0.001), and anterior pelvic tilt (before = 7.2° ± 5.1°, after = 13.3° ± 6.7°, P = 0.001) after the exhaustive run compared to controls. Trunk flexion increased in both PFP (before = 13.09° ± 6.2°, after = 16.31° ± 5.3°, P < 0.001) and control (before = 1393° ± 4.7°, after = 15.99° ± 5.9°, P < 0.001) groups. Hip extension (before = −2.09 ± 0.49 N·m·kg, after = −2.49 ± 0.54 N·m·kg, P = 0.002) moments increased only in subjects with PFP.
CONCLUSIONSExhaustive running results in reduced hip strength in subjects with PFP; however, this did not result in changes to hip internal rotation or adduction kinematics. Kinematic and kinetic changes after the exhaustive run are more indicative of compensatory changes to reduce pain. Increasing trunk flexion during running might provide pain relief during running; however, reducing anterior pelvic tilt may also warrant attention during treatment.
June consultation #6 Armstrong, Brian K.
Journal of cataract and refractive surgery,
June 2018, 2018-Jun, 2018-06-00, 20180601, Volume:
44, Issue:
6
Journal Article
The aim of this study was the development and evaluation of a real-time guidance support using optical Moiré Phase Tracking (MPT) for magnetic resonance (MR) guided percutaneous interventions. A ...gradient echo sequence, capable of real-time position updates by the MPT system, was modified to enable needle guidance based on four rigidly attached MPT markers at the back of a needle. Two perpendicular imaging planes were automatically aligned along the calibrated needle and centered at its tip. For user guidance, additional information about the needle trajectory and the tip to target distance were added as image overlay. Both, images and guiding information were displayed on the in-room monitor to facilitate MR guided interventions. The guidance support was evaluated by four experienced interventional radiologists and four novices targeting rubber O-rings embedded in a custom-made phantom on a 3T wide-bore MRI system (80 punctures). The skin to target time, user error, system error and total error were analyzed. The mean skin to target time was 146s±68s with no statistically significant difference between experts and novices. A low mean user error (0.91mm±0.43mm), system error (0.53mm±0.27mm) and total error (0.99mm±0.47mm) was reached in all directions. No statistically significant difference in user error, system error and total error could be found between experts and novices. The presented tracking and image guidance system combined with the user interface offers continuous and interactive control of the imaging plane while puncturing in the magnet enabling accurate real-time feedback for both, experienced and non-experienced users.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract Background Dynamic knee stability is considered a critical factor in reducing anterior cruciate ligament loads. While the relationships between hamstring force production and anterior ...cruciate ligament loading are well known in vitro, the influence of hamstring strength to anterior cruciate ligament loading during athletic maneuvers remains unknown. Therefore, the purpose of this study was to determine the influence of hamstring strength on anterior cruciate ligament loading during anticipated sidestep cut. Methods Seventeen recreationally active females were recruited to perform sidestep cutting maneuvers pre/post an acute hamstring strength reduction protocol. Kinematics and kinetics were calculated during the cut and a musculoskeletal model was used to estimate muscle, joint, and anterior cruciate ligament loads. Dependent t-tests were conducted to investigate differences between the two cutting conditions. Findings Anterior cruciate ligament loading increased by 36% due to reduced hamstring strength. This was mostly due to a 44% increase in sagittal plane loading and a 24% increase in frontal plane loading. Post strength reduction sidestep cuts were also performed with decreased anterior tibiofemoral shear force, an outcome that would theoretically reduce anterior cruciate ligament loading. However, the overall decrease in hamstring force production coupled with a more axial hamstring line of action yielded a net increase in anterior cruciate ligament loading. Interpretation These results suggest that decreased hamstring strength significantly increases anterior cruciate ligament loading during anticipated sidestep cutting. Additionally, these results support the premise that preseason screening programs should monitor hamstring strength to identify female athletes with potential deficits and increased injury risk.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Brown adipose tissue (BAT), as the main site of adaptive thermogenesis, exerts beneficial metabolic effects on obesity and insulin resistance. BAT has been previously assumed to contain a homogeneous ...population of brown adipocytes. Utilizing multiple mouse models capable of genetically labeling different cellular populations, as well as single-cell RNA sequencing and 3D tissue profiling, we discovered a brown adipocyte subpopulation with low thermogenic activity coexisting with the classical high-thermogenic brown adipocytes within the BAT. Compared with the high-thermogenic brown adipocytes, these low-thermogenic brown adipocytes had substantially lower Ucp1 and Adipoq expression, larger lipid droplets, and lower mitochondrial content. Functional analyses showed that, unlike the high-thermogenic brown adipocytes, the low-thermogenic brown adipocytes have markedly lower basal mitochondrial respiration, and they are specialized in fatty acid uptake. Upon changes in environmental temperature, the 2 brown adipocyte subpopulations underwent dynamic interconversions. Cold exposure converted low-thermogenic brown adipocytes into high-thermogenic cells. A thermoneutral environment had the opposite effect. The recruitment of high-thermogenic brown adipocytes by cold stimulation is not affected by high-fat diet feeding, but it does substantially decline with age. Our results revealed a high degree of functional heterogeneity of brown adipocytes.
Understanding the extinction of
and origins of
and
in South Africa has been hampered by the perceived complex geological context of hominin fossils, poor chronological resolution, and a lack of ...well-preserved early
specimens. We describe, date, and contextualize the discovery of two hominin crania from Drimolen Main Quarry in South Africa. At ~2.04 million to 1.95 million years old, DNH 152 represents the earliest definitive occurrence of
, and DNH 134 represents the earliest occurrence of a cranium with clear affinities to
These crania also show that
,
, and
were contemporaneous at ~2 million years ago. This high taxonomic diversity is also reflected in non-hominin species and provides evidence of endemic evolution and dispersal during a period of climatic variability.
Noninvasive biomarkers are needed to monitor stable patients after kidney transplant (KT), because subclinical acute rejection (subAR), currently detectable only with surveillance biopsies, can lead ...to chronic rejection and graft loss. We conducted a multicenter study to develop a blood‐based molecular biomarker for subAR using peripheral blood paired with surveillance biopsies and strict clinical phenotyping algorithms for discovery and validation. At a predefined threshold, 72% to 75% of KT recipients achieved a negative biomarker test correlating with the absence of subAR (negative predictive value: 78%‐88%), while a positive test was obtained in 25% to 28% correlating with the presence of subAR (positive predictive value: 47%‐61%). The clinical phenotype and biomarker independently and statistically correlated with a composite clinical endpoint (renal function, biopsy‐proved acute rejection, ≥grade 2 interstitial fibrosis, and tubular atrophy), as well as with de novo donor‐specific antibodies. We also found that <50% showed histologic improvement of subAR on follow‐up biopsies despite treatment and that the biomarker could predict this outcome. Our data suggest that a blood‐based biomarker that reduces the need for the indiscriminate use of invasive surveillance biopsies and that correlates with transplant outcomes could be used to monitor KT recipients with stable renal function, including after treatment for subAR, potentially improving KT outcomes.
The authors present data for a blood‐based gene expression profile that can be used to detect and monitor the treatment of subclinical rejection in patients following kidney transplantation. See Naesens's editorial on page 5.
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BFBNIB, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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