Swithin Song

Measurement of liver fat by magnetic resonance imaging: relationships with body fat distribution, insulin sensitivity and plasma lipids in healthy men

Aim:  We compared the use of magnetic resonance imaging (MRI) as a test for liver fat content (LFAT) with proton magnetic resonance spectroscopy (MRS) and investigated its relationship with body fat distribution, insulin sensitivity, plasma lipids and lipoproteins.

Influence of age and gender on thoracic vertebral body shape and disc degeneration: an MR investigation of 169 cases.

There are limited data detailing the pattern of age and gender‐related changes to the thoracic vertebral bodies and intervertebral discs. A retrospective MR investigation, involving T1‐weighted midsagittal images from 169 cases, was undertaken to examine age influences on the anterior wedge (anteroposterior height ratio or Ha/Hp), biconcavity (midposterior height ratio or Hm/Hp), and compression indices (posterior height/anteroposterior diameter or Hp/D) of the thoracic vertebral bodies. Disc degenerative changes in the annulus, nucleus, end‐plate and disc margin were noted on T2‐weighted sagittal images for the 169 cases, based on a 3‐level grading system. A linear age‐related decline in the Ha/Hp and Hm/Hp indices was noted. The Hp/D index increased during the first few decades of life, then decreased gradually thereafter. The prevalence of abnormal findings in the annuli, nuclei and disc margins increased with increasing age, particularly in the mid and lower thoracic discs. Greater disc degenerative changes were observed in males. These findings provide further insight into the nature of thoracic vertebral shape changes across the lifespan, and the typical patterns of degeneration of the thoracic intervertebral discs.

Humoral Factors Enhance Fracture-Healing and Callus Formation in Patients with Traumatic Brain Injury

BACKGROUND Scientific evidence is mounting for an association between traumatic brain injury and enhanced osteogenesis. The aim of this study was to correlate the in vitro osteoinductive potential of serum with the features of fracture-healing and the extent of brain damage in patients with severe traumatic brain injury and bone fracture. METHODS Patients with a long-bone fracture and a traumatic brain injury (seventeen patients) or without a brain injury (twenty-four patients) were recruited. The Glasgow Coma Scale score was determined on admission. Radiographs of the fracture were made before surgery, at six weeks, and at three, six, and twelve months after surgery. The time to union was estimated clinically and radiographically, and the callus ratio to shaft diameter was calculated. Serum samples were collected at six, twenty-four, seventy-two, and 168 hours after injury, and their osteogenic potential was determined by measurement of the in vitro proliferation rate of the human fetal osteoblastic cell line hFOB1.19. RESULTS Patients with a traumatic brain injury had a twofold shorter time to union (p = 0.01), a 37% to 50% increased callus ratio (p < 0.01), and their sera induced a higher proliferation rate in hFOB cells (p < 0.05). A linear relationship was revealed between hFOB cell proliferation rates and the amount of callus formed (p < 0.05). The Glasgow Coma Scale score was correlated with the callus ratio on both radiographic projections (p < 0.05), time to union (p = 0.04), and the proliferation rate of hFOB cells at six hours after injury (p = 0.03). CONCLUSIONS Patients with a severe brain injury release unknown humoral factors into the blood circulation that enhance and accelerate fracture-healing.

Magnetic resonance-based vertebral morphometry of the thoracic spine: age, gender and level-specific influences

OBJECTIVE The aim of this study was to examine age, gender, and segmental trends in thoracic vertebral body shape, utilising thoracic spine magnetic resonance images involving an age range spanning the life span. DESIGN A quantitative, cross-sectional, retrospective study design involving a sample of convenience. BACKGROUND Thoracic vertebral shape data are commonly derived from radiographic resources. The non-ionising properties of magnetic resonance imaging and availability of digital data for image analysis suggest potential for MR-based morphometric studies. For the thoracic spine, there is limited vertebral shape data on males, while few studies have examined the pattern of age-related changes across the life span. METHODS Morphometry was performed on 220 mid sagittal T1-weighted MR images using image analysis software. Three indices of vertebral shape were utilised: the antero-posterior height ratio or anterior wedge index, mid-posterior height ratio or biconcavity index, and ratio of posterior vertebral height to mid antero-posterior diameter or compression index. RESULTS Different segmental patterns were noted for the vertebral shape indices. Significantly lower mean values were noted in males for the compression index. Age trends were significant, with a linear age-related decline demonstrated for the anterior wedge and biconcavity indices, and a quadratic trend noted for the compression index. CONCLUSIONS Thoracic vertebral body shape may be uniquely described using specific shape indices, for examining various segmental, gender and age-associated changes. RELEVANCE These results suggest the importance of defining specific reference criteria for thoracic vertebral body shape indices, particularly age-related data encompassing a wide age range. Magnetic resonance studies enable interpretation of vertebral shape data in relation to the wide spectrum of pathologies afflicting the thoracic spine, without the concerns of ionising radiation.

An open label pilot investigation of the efficacy of Botulinum toxin type A [Dysport] injection in the rehabilitation of chronic anterior knee pain

Purpose. To examine the effect of intramuscular injection of botulinum toxin type A [Dysport®] to reduce relative overactivity of the vastus lateralis [VL] muscle, in conjunction with re-training of vastus medialis [VM] muscle as an adjunct to rehabilitation for chronic anterior knee pain. Method. Eight females with chronic (>6 months) history of anterior knee pain, who had failed conservative management, were studied in this open label pilot study. Intramuscular Dysport® injection [300 – 500 units] to the distal third of VL muscle was followed by a 12-week customized home exercise programme to improve recruitment of VM muscle and functional knee control. VL and VM muscle cross sectional area from a standardized spiral CT sequence, isometric quadriceps strength (dynamometry), timed stair task, self-reported pain and disability were assessed. Results. Subjects reported reduced knee pain and brace dependency and increased participation in sporting and daily living activities. Isometric quadriceps muscle strength was maintained or improved despite significant atrophy, evident on CT, of the distal component of VL in the treated limb. Time taken to ascend and descend a flight of stairs improved in all subjects. Subjective and objective improvements were maintained at 24-week follow-up. Conclusions. These pilot data provide preliminary support for the role of Dysport® as an adjunct to non-surgical management of individuals with chronic anterior knee pain. Larger double blind, randomized, placebo-injection controlled studies of this novel approach to improving patellofemoral mechanics are needed to establish the efficacy of this intervention.

Thymic tissue is not evident on high-resolution computed tomography and [18F]Fluoro-deoxy-glucose positron emission tomography scans of aviraemic HIV patients with poor recovery of CD4+ T cells

Some previously immunodeficient HIV patients responding to antiretroviral therapy display poor recovery of CD4+ T cells. Evaluation of the contribution of thymic function requires sensitive detection and quantitation of metabolically active thymic tissue. We describe patients with low but detectable thymopoiesis assessed as circulating CD4+ naive T cells expressing CD31. High-resolution computed tomography and PET scans found no residual thymic tissue even though metabolic activity was demonstrable by PET in lymph nodes.

Nucleus pulposus deformation in response to rotation at L1–2 and L4–5

BACKGROUND Spinal rotation couples with lateral flexion as a composite movement. Few data report the in vivo mechanical deformation of the nucleus pulposus following sustained rotation. MRI provides a non-invasive method of examining nucleus pulposus deformation by mapping the hydration signal distribution within the intervertebral disc. METHODS T1 weighted coronal and sagittal lumbar images and T2 weighted axial images at L1-2 and L4-5 were obtained from 10 asymptomatic subjects (mean age 29, range: 24-34 years) in sustained flexed and extended positions plus combined positions of left rotation with flexion and extension. Nucleus pulposus deformation was tracked by mapping the change in hydration profiles from coronal and sagittal pixel measurements. FINDINGS An average sagittal change in position of 44° (SD 14.5°) from flexion to extension was recorded between L1 and S1 (range: 18°- 60°) resulting in a mean anterior nucleus pulposus deformation of 16% of disc hydration profile (range: 3.5%-19%) in 19/20 discs. When rotation was combined with either flexion or extension, mean coronal deformation was 4.8% (SD-5.1%; range: 0.4%-15%). Lateral nucleus pulposus deformation direction varied in rotation (44% deformed left and 56% deformed right). Intersegmental lateral flexion direction more strongly predicted nucleus pulposus deformation direction with 75% deforming contralaterally. INTERPRETATION Nucleus pulposus deformation direction in young subjects was more predictable following sagittal position change than in rotation combined with flexion or extension. Deformation magnitude was reduced in rotated positions. Intersegmental lateral flexion was a stronger predictor of nucleus pulposus deformation direction.

Lipoprotein Metabolism in APOB L343V Familial Hypobetalipoproteinemia

CONTEXT Familial hypobetalipoproteinemia (FHBL) is a codominant disorder of lipoprotein metabolism characterized by decreased plasma concentrations of low-density lipoprotein (LDL)-cholesterol and apolipoprotein B (apoB). OBJECTIVE The objective was to examine the effect of heterozygous APOB L343V FHBL on postprandial triglyceride-rich lipoprotein (TRL) and fasting lipoprotein metabolism. METHODS Plasma incremental area under the curve apoB-48 and apoB-48 kinetics were determined after ingestion of a standardized oral fat load using compartmental modeling. Very low-density lipoprotein (VLDL)-, intermediate-density lipoprotein (IDL)-, and LDL-apoB kinetics were determined in the fasting state using stable isotope methods and compartmental modeling. RESULTS The postprandial incremental area under the curve (0-10 h) in FHBL subjects (n = 3) was lower for large TRL-triglyceride (-77%; P < .0001), small TRL-cholesterol (-83%; P < .001), small TRL-triglyceride (-88%; P < .001), and for plasma triglyceride (-70%; P < .01) and apoB (-63%; P < .0001) compared with controls. Compartmental analysis showed that apoB-48 production was lower (-91%; P < .05) compared with controls. VLDL-apoB concentrations in FHBL subjects (n = 2) were lower by more than 75% compared with healthy, normolipidemic control subjects (P < .01). The VLDL-apoB fractional catabolic rate (FCR) was more than 5-fold higher in the FHBL subjects (P = .07). ApoB production rates and IDL- and LDL-apoB FCRs were not different between FHBL subjects and controls. CONCLUSIONS We conclude that when compared to controls, APOB L343V FHBL heterozygotes show lower TRL production with normal postprandial TRL particle clearance. In contrast, VLDL-apoB production was normal, whereas the FCR was higher in heterozygotes compared with lean control subjects. These mechanisms account for the marked hypolipidemic state observed in these FHBL subjects.

Reliability of a modified grading scheme for MRI assessment of thoracic intervertebral discs

The study aimed to investigate the variability in interpreting magnetic resonance imaging (MRI) films for thoracic disc degeneration, using a 5-point MRI disc grading scale and a modified 3-point scale. Forty-six T2-weighted sagittal thoracic MRI films, comprising 18 males and 28 females, aged 7 to 73 years, (mean age =41±16.3 years), were randomly selected from 318 archived cases. Nuclear and anular degeneration, end-plate lesions and osteophytes were graded on the first 30 cases using a modified 3-point grading scale. The next 30 cases were evaluated using the 5-point grading scale. Repeat evaluations for both scales were conducted after a three- to six-month interval. The intra-rater kappa coefficient was higher using the 3-point scale (0.71 to 0.87, p < 0.001) compared to the 5-point scale (0.57 to 0.78, p < 0.001) for the end-plate–disc–end-plate components. The lowest intra-rater reliability was for osteophytes and the highest was for the nucleus. The intra-rater reliability was generally higher in the upper thoracic region compared to the mid and lower thoracic regions.

Lipoprotein metabolism in an apoB-80 familial hypobetalipoproteinemia heterozygote

OBJECTIVE Familial hypobetalipoproteinemia (FHBL) is characterized by mutations in APOB, the majority of these causing protein truncations, and low plasma levels of apolipoprotein (apo) B. The hypobetalipoproteinemia may be due to enhanced clearance and possibly reduced production of apoB-containing lipoproteins; the mechanism may depend on the length of the apoB truncation. We studied fasting lipoprotein metabolism in an FHBL subject heterozygous for a mutation causing a truncated apoB, apoB-80. DESIGN AND METHODS Very low density lipoprotein (VLDL)-, intermediate density lipoprotein (IDL)-, and low density lipoprotein (LDL)-apoB kinetics were determined in the fasting state using stable isotope methods and compartmental modeling. RESULTS Compared with lean normolipidemic controls the apoB-80 FHBL subject had an elevated VLDL-apoB fractional catabolic rate and lower LDL production. ApoB production rates and IDL- and LDL-apoB fractional catabolic rates were not different. CONCLUSION FHBL subjects heterozygous for a mutation truncating apoB to 80% of full-length are able to produce VLDL-apoB normally, but have rapid clearance of these particles, resulting in low levels of circulating apoB.