Predicting abdominal adipose tissue in overweight Latino youth.

OBJECTIVES: 1) Examine associations between visceral adipose tissue (VAT), subcutaneous abdominal adipose tissue (SAAT), and anthropometric and demographic variables; 2) generate and cross-validate prediction equations for estimating VAT and SAAT in overweight Latino children. STUDY DESIGN: Cross-sectional. PARTICIPANTS: 196 overweight 8-13-year-old Latino youth. Two-thirds (n = 131) were randomly assigned to a development group to generate prediction equations for VAT and SAAT; one-third (n = 65) was used as a cross-validation group. METHODS AND PROCEDURES: Anthropometric measurements (height, weight, skinfold thicknesses, and circumferences) were performed. VAT and SAAT were measured using magnetic resonance imaging (MRI). RESULTS: The strongest univariate correlate for VAT was waist circumference (WC) (r = 0.65, p < 0.01) while the strongest correlate for SAAT was hip circumference (r = 0.88, p < 0.001). Regression analyses showed approximately 50% of the variance in VAT was explained by WC (43.8%), Tanner stage (4.2%) and calf skinfold (1.7%). Variance in the SAAT model was explained by WC (77.8%), triceps skinfold (4.2%) and gender (2.3%). Residual analyses showed no bias in either equation. Though mean differences between measured and predicted VAT and SAAT were small, there was a large degree of variability at the individual level especially for VAT. CONCLUSIONS: Both VAT and SAAT prediction equations performed well at the group level, but the relatively high degree of variability suggests limited clinical utility of the VAT equation. MRI is currently required to derive an accurate measure of VAT at the individual level.     

The efficacy of ECT in mixed affective states

ECT is efficacious in the treatment of both the depressed and manic phases of bipolar disorder. While ECT is believed to be equally efficacious in the treatment of mixed affective states, to our knowledge there are no empirical studies on this issue. A chart review study was conducted to compare treatment response and clinical course in three groups of patients who received ECT in a general hospital service: bipolar depressed (n = 38), bipolar manic (n = 5), and bipolar mixed (n = 10), diagnosed by DSM-IV criteria. All three groups showed robust response rates, but the number of days of hospitalization was significantly longer in the mixed group (mean 30, SD 19.0 days) compared with the depressed group (mean 19.0, SD 10.9 days, t = 2.4, p < 0.03). There was a trend for the number of ECT treatments to be greater in the mixed compared with the depressed group. These findings indicate that patients with mixed affective states do respond well to a course of ECT, but the longer hospital stays and greater number of ECT treatments suggest that they may be more difficult to treat with ECT than patients with pure bipolar depression or bipolar mania.     

Permeabilisation and solubilisation of soybean phosphatidylcholine bilayer vesicles, as membrane models, by polysorbate, Tween 80.

To understand better the wide-spread pharmaceutical use of non-ionic surfactant Tween 80 (TW), the colloidal properties of the surfactant alone and in combinations with the common phospholipid, phosphatidylcholine (PC), were studied. Static and dynamic light scattering revealed that TW solubilises PC at TW/PC approximately 2.75/1 mol/mol and that TW micelle disintegration occurs on time-scale of 2.5 min, independent of amphipath concentration. This is up to nearly 300-times faster than the TW caused dissolution of PC containing unilamellar vesicles. The apparent dissolution time of TW/PC mixed aggregates, in contrast, decelerates from >700 min to <5 min upon increasing starting total amphipath concentration, with thermal activation energy > or =24 (< or =80) kJ mol(-1). The aggregate dissolution rate in highly concentrated TW/PC suspensions reflects the dissolved polysorbate-aggregate exchange rate (approximately 6.7 x 10(-3)s(-1)) rather than TW flip-flop rate across a bilayer (>0.2 min(-1)). PC solubilisation proceeds linearly with the square-root of time, and is kinetically governed by the speed of surfactant diffusion through the bulk (D approximately 2.8 x 10(-11)m2 s(-1)). Creation of small Tween-phosphatidylcholine mixed micelles is typically preceded by pre-solubilisation structures, first in the form of deformable, strongly fluctuating, bilayer vesicles and then of elongated, presumably thread-like, mixed micelles. TW/PC mixed micelles become smaller with growing surfactant/lipid molar ratio, whereas TW/PC mixed vesicles become more and more leaky with increasing surfactant concentration. Our results highlight the molecular and kinetic aspects of polysorbate-membrane interactions and provide a rationale for the popularity of Tween surfactants in pharmaceutical products: such surfactants can solubilise fatty molecules and bilayer membranes but need quite a long time for this, which is available in pharmaceutical preparations but normally not in vivo; this makes Tweens relatively efficient and safe. Furthermore, our data could help design better ultra-deformable mixed lipid-surfactant vesicles for the non-invasive transdermal drug delivery across the skin.     

The effect of cholate on solubilisation and permeability of simple and protein-loaded phosphatidylcholine/sodium cholate mixed aggregates designed to mediate transdermal delivery of macromolecules.

Carriers for non-invasive administration of biologically important antioxidant enzymes Cu,Zn-superoxide dismutase (SOD) and catalase (CAT) were developed. Solubilisation and permeabilities of various soybean phosphatidylcholine/sodium cholate (SPC/NaChol) mixtures, mainly in the form of lipid bilayers, focussing on system properties relevant for non-invasive enzyme delivery were investigated in this work. Static and dynamic light scattering measurements gave information on the behaviour of the systems containing up to 40 mM NaChol and 30.6-1.2 mM SPC in the final suspension. The average size of such mixed aggregates was in the 100-200 nm range. Suspension turbidity decreased by 50% upon increasing nominal molar detergent/lipid ratio to NaChol/SPC = 7 and 1.25, in case of SPC = 1.2 and 19.6 mM, respectively. The effective NaChol/SPC molar ratio in bilayers saturated with the detergent was found to be: R(e)(sat) = 0.70 +/- 0.01; bilayer solubilisation point corresponded to R(e)(sol) = 0.97 +/- 0.02, independently of enzyme loading. Vesicles became very permeable to SOD when membrane bound NaChol concentration exceeded 13.7 mM, in case of total starting lipid concentration of 138 mM diluted to SPC = 19.6 mM. Specifically, we measured a 50% loss of SOD from the vesicles with an aggregate-associated molar detergent ratio NaChol/SPC approximately 0.7, which is near the saturation but well below the solubilisation limit. Calcein efflux from such vesicles was compared with SPC/NaChol/SOD mixed aggregates. Our results should contribute to the future design of vesicle mediated transdermal delivery of antioxidant enzymes.     

Organ slice viability extended for pathway characterization: an in vitro model to investigate fibrosis.

Liver slice viability is extended to 96 h for rat, expanding the use of this in vitro model for studying mechanisms of injury and repair, including pathways of fibrosis. The contributing factors to increased organ slice survival consist of the use of a preservation solution for liver perfusion and slice preparation, obtaining rats that are within the weight range of 250-325 g, placing a cellulose filter atop the titanium mesh roller-insert to support the slice, and maintaining the slices in an optimized culture medium which is replaced daily. The liver slices remain metabolically active, synthesizing adenosine triphosphate (ATP), glutathione, and glycogen, and exhibit preserved organelle integrity and slice morphology. Slice preparation results in 2-cut surfaces which likely triggers a repair and regenerative response. The fibrogenic pathways are evident by the activation of stellate cells, the proliferation of myofibroblast-like cells, and an increased collagen deposition by 48 h. Markers indicative of activated stellate cells, alpha-smooth muscle actin, collagen 1a1, desmin, and HSP47 are substantiated by real time-PCR. Increased staining of alpha-smooth muscle actin initially around the vessels and by 72-96 h in the tissue is accompanied by increased collagen staining. Microarray gene expression revealed extracellular matrix changes with the up-regulation of cytoskeleton, filaments, collagens, and actin genes; and the down-regulation of genes linked with lipid metabolism. The improvements in extending liver slice survival, in conjunction with its three-dimensional multi-cellular complexity, increases the application of this in vitro model for investigating pathways of injury and repair, and fibrosis.