Diffusion-weighted MR imaging of the liver of hepatitis C patients

Magnetic resonance diffusion-weighted imaging (DWI) of the liver was investigated to determine whether this method could be used to differentiate between the stages of fibrosis and inflammation for hepatitis C viral infection. DWI data were recorded for 18 hepatitis C patients and 10 control subjects using a modified pulse sequence allowing a 52 ms echo time delay. Acquisitions were performed with breath holding using five different b gradient factor values ranging between 50 and 250 s/mm(2) and in the three axes. Apparent diffusion coefficient (ADC) values were measured from a 5.7 cm(2) area in the central region of the liver. The inflammation and fibrosis grades were evaluated histologically on a biopsy sample. The mean ADC values were 2.30 +/- 1.28 x 10(-3) and 1.79 +/- 0.25 x 10(-3) mm(2)/s for hepatitis C patients and control subjects, respectively. Using our technique, no correlation could be found between the ADC values and the inflammation or fibrosis scores, indicating that tissue changes produced by hepatitis C do not appear to be quantifiable by DWI.     

Response rates for providing a blood specimen for HIV testing in a population-based survey of young adults in Zimbabwe

Background  

To determine differences among persons who provided blood specimens for HIV testing compared with those who did not among those interviewed for the population-based Zimbabwe Young Adult Survey (YAS).     

Effect of exogenous surfactant on total respiratory system compliance

We measured total respiratory system compliance (Crs) before and after instilling 25 mg artificial surfactant in 1 ml saline down the endotracheal tube of preterm babies requiring resuscitation at birth, and compared results with data from 6 similar babies receiving saline only. Surfactant did not produce a significant improvement in Crs.     

A prototype HeartQuest ventricular assist device for particle image velocimetry measurements

The objective of this study is to fully characterize the flow within the HeartQuest ventricular assist device (VAD), a magnetically levitated centrifugal VAD, using particle image velocimetry (PIV) to identify regions of potential high shear or stagnation and validate and refine computational models of the flow. An acrylic model of the pump was designed and constructed to allow optical access into all interior regions of the pump. The geometry of the exterior housing and the use of a novel working fluid make quantitative measurements of velocity within the exit volute, blade passage, cut-water, blade tip clearance, and pump inlet possible. Highly accurate velocity measurements using particle PIV have been made in one region (the inlet elbow), and measurements in the other critical regions of the pump will be made. These measurements are used for investigation of regions with potential for hemolysis resulting from high shear stress or with potential for thrombosis caused by recirculation or stagnation. Quantitative velocity data are also needed for comparison with computational fluid dynamics (CFD) models of the VAD. In this study, experiments have again proven to be an essential complement to CFD for thorough investigations of the flow inside the pump.     

Should the guidelines for monitoring serum cholesterol levels in the elderly be re-evaluated?

Elevated circulating cholesterol can have profound effects on the health of an individual. Such excess cholesterol can promote coronary artery disease, production and accumulation of β-amyloid in the brain, and possibly Alzheimer’s disease (AD). In a clinical trial evaluating the benefit of a cholesterol-lowering drug in the treatment of AD, mean cholesterol levels at baseline among individuals participating in the trial were found to be relatively high. Based on this observation we suggest that cholesterol levels should be actively monitored in the elderly, as many individuals with AD are over 65 years of age and therefore excluded by currently accepted guidelines.     

Lipofuscin accumulation in the vastus lateralis muscle in patients with chronic obstructive pulmonary disease

Exercise-induced oxidative stress has been reported in patients with chronic obstructive pulmonary disease (COPD) and may play a role in muscle fatigue. It is speculated that oxidative stress during exercise originates from the contracting muscles but this has not been documented. The accumulation of lipofuscin, a marker of cellular oxidative damage, was evaluated in the vastus lateralis muscle in 17 patients with COPD and 10 healthy subjects of similar age. Each subject performed a stepwise exercise test up to maximal capacity during which oxygen uptake (VO(2)) was measured. Resting and peak exercise blood gases were also obtained. Two indices of lipofuscin accumulation were used: lipofuscin inclusions/fiber ratio (LI/F) and lipofuscin inclusions/fiber cross-sectional area ratio (LI/CSA). These ratios were also determined for each specific fiber-type. LI/F (P < 0.01) and LI/CSA (P < 0.01) were greater in COPD compared to healthy subjects. LI/F and LI/CSA for all fiber types were also greater in COPD (P < 0.001). In both groups, LI/F (P < 0.001) and LI/CSA (P < 0.01) were higher in type I than in type II fibers. LI/F and LI/CSA did not correlate significantly with resting PaO(2) and SaO(2), peak VO(2), and DeltaPaO(2) and DeltaSaO(2) during exercise (P > 0.05). Increased lipofuscin accumulation, a marker of oxidative damage, was found in the vastus lateralis muscle in patients with COPD compared to healthy subjects. Oxidative damage of muscle tissue may thus be involved in skeletal muscle dysfunction and wasting in COPD.     

Whole body protein metabolism in children with cancer

Whole body protein synthesis and catabolism were measured using the [ring-2H5]phenylalanine and [1-13C]leucine primed constant infusion technique in 32 paediatric patients with cancer at different stages of treatment. Rates of synthesis (S) and catabolism (C) derived from the [ring-2H5]phenylalanine and [1-13C]leucine models were 4.7 (SD 1.3) (S) and 6.0 (1.5) (C) g/d/kg, and 5.5 (0.8) (S) and 6.8 (1.2) (C) g/d/kg, respectively. These results show that these two tracer techniques give similar results in this study population. Comparison of these values with results previously reported for groups of control children using the [ring-2H5]phenylalanine model (S = 3.69 and 3.93; C = 4.09 and 4.28 g/d/kg) and the [1-13C]leucine model (S = 4.32; C = 4.85 g/d/kg) show that rates of synthesis and catabolism were higher in cancer patients than in controls. Thus whole body protein turnover is increased in children under treatment for cancer. Other indices of metabolism such as plasma amino acids and intermediary metabolites were also measured and showed that, although subjects were in isotopic steady state, there were significant metabolic changes during the course of the primed constant infusions used to measure protein turnover.     

East and South East Asian Ethnicity and Moderate-to-Severe Endometriosis

Study Objective

To investigate ethnic differences for moderate-to-severe endometriosis.