Arsenic species in ecosystems affected by arsenic-rich spring water near an abandoned mine in Korea

The objectives of this study were to quantitatively estimate the distribution of arsenic with its speciation and to identify potential pathways for transformation of arsenic species from samples of water, sediments, and plants in the ecosystem affected by the Cheongog Spring, where As(V) concentration reached levels up to 0.270 mg L(-1). After flowing about 100 m downstream, the arsenic level showed a marked reduction to 0.044 mg L(-1) (about 84% removal) without noticeable changes in major water chemistry. The field study and laboratory hydroponic experiments with the dominant emergent plants along the creek (water dropwort and thunbergian smartweed) indicated that arsenic distribution, reduction, and speciation appear to be controlled by, (i) sorption onto stream sediments in exchangeable fractions, (ii) bioaccumulation by and possible release from emergent plants, and (iii) transformation of As(V) to As(III) and organic species through biological activities.

Unilateral buttock reconstruction using contralateral inferior gluteal artery perforator flap with the aid of multi-detector CT

SUMMARY

The applicability of inferior gluteal artery perforator (IGAP) flaps in breast reconstruction following breast cancer has been well described. However, the use of IGAP flaps in buttock augmentation has not been presented. We present the case of a female patient with buttock asymmetry and a deficiency of volume, who underwent buttock reconstruction based on a contralateral IGAP flap. Multidetector computed tomography (MDCT) was used to study donor and recipient areas, and allowed easy interpretation as it provided anatomical images and three-dimensional anatomy reconstructions. Based on a knowledge of individual anatomical perforating vessel distributions, safe perforator flaps can be designed. Moreover, we are convinced that buttock reconstruction using autologous tissue can be performed in a safe and reliable fashion using perforator flaps. Donor site morbidity was minimal and the muscle at the donor site was preserved. The contralateral buttock proved an excellent donor site for aesthetic unilateral buttock reconstruction and provided ample tissue in the described case.

Effect of cryoprotectants on the reconstitution of surfactant-free nanoparticles of poly(DL-lactide-co-glycolide)

Various cryoprotectants were tested to reconstitute the surfactant-free nanoparticles of poly(DL-lactide-co-glycolide) (PLGA). When 2.0% (w/v) of sucrose, trehalose and lactose were used, nanoparticles were completely reconstituted into aqueous solution and particle size was not significantly changed. Above 1.0% (w/v) of sucrose, trehalose and lactose, nanoparticles are well reconstituted whereas it was precipitated with 1.0% (w/v) of mannitol. Drug-encapsulated surfactant-free nanoparticles were quite reconstituted when 2.0% (w/v) of sucrose, trehalose and lactose. Drug release kinetics of nanoparticles was not significantly changed by cryoprotectants.

CREB regulates hepatic gluconeogenesis through the coactivator PGC-1

When mammals fast, glucose homeostasis is achieved by triggering expression of gluconeogenic genes in response to glucagon and glucocorticoids. The pathways act synergistically to induce gluconeogenesis (glucose synthesis), although the underlying mechanism has not been determined. Here we show that mice carrying a targeted disruption of the cyclic AMP (cAMP) response element binding (CREB) protein gene, or overexpressing a dominant-negative CREB inhibitor, exhibit fasting hypoglycaemia [corrected] and reduced expression of gluconeogenic enzymes. CREB was found to induce expression of the gluconeogenic programme through the nuclear receptor coactivator PGC-1, which is shown here to be a direct target for CREB regulation in vivo. Overexpression of PGC-1 in CREB-deficient mice restored glucose homeostasis and rescued expression of gluconeogenic genes. In transient assays, PGC-1 potentiated glucocorticoid induction of the gene for phosphoenolpyruvate carboxykinase (PEPCK), the rate-limiting enzyme in gluconeogenesis. PGC-1 promotes cooperativity between cyclic AMP and glucocorticoid signalling pathways during hepatic gluconeogenesis. Fasting hyperglycaemia is strongly correlated with type II diabetes, so our results suggest that the activation of PGC-1 by CREB in liver contributes importantly to the pathogenesis of this disease.

Minimization of MC1R selectivity by modification of the core structure of alpha-MSH-ND

BACKGROUND

Melanocortin, through its distinct receptor subtypes, has many different effects. Receptor-selective ligands are required to reduce the undesirable effects of melanocortin. To investigate which conformation is preferable to a given melanocortin receptor subtype, a structural and functional analysis of the ligand-receptor interactions was made by studying the biological activity, the nuclear magnetic resonance structures, and the patterns of the ligand-receptor interaction for each receptor subtype by homology modeling analysis.

RESULTS

Among the several analogues examined, [Gln(6)]alpha-melanocyte-stimulating hormone (MSH)-ND was found to have 10000 times less biological activity than alpha-MSH-ND for the MC1R, whereas, the potencies of both oligopeptides were comparable in both the melanocortin-3 receptor (MC3R) and MC4R. [Gln(6)]alpha-MSH-ND exhibited a type I' beta-turn that was similar to the type I beta-turn structure of alpha-MSH-ND. However, a remarkable structural difference was observed with respect to the side chain orientations of the sixth and seventh residues of [Gln(6)]alpha-MSH-ND, which were found to be mirror images of alpha-MSH-ND. By homology modeling analysis, the His(6) of alpha-MSH-ND was found to interact with the TM2 regions of all three receptors (Glu(94) of MC1R, Glu(94) of MC3R, and Glu(100) of MC4R), but [Gln(6)]alpha-MSH-ND did not. The phenyl ring of the D-Phe(7) residue of [Gln(6)]alpha-MSH-ND revealed an interaction with the TM3 regions of both the MC3R and MC4R (Ser(122) of MC3R or Ser(127) of MC4R). However, in the MC1R, these serine residues corresponded to Val(122), which contains two methyl groups that induce steric hindrance with D-Phe(7) of [Gln(6)]alpha-MSH-ND. This is a possible explanation for the biological activity of [Gln(6)]alpha-MSH-ND for the MC1R being significantly lower than that for either the MC3R or MC4R.

CONCLUSIONS

Minimization of the MC1R selectivity whilst preserving its comparable potency for both the MC3R and MC4R could be achieved by modifying the D-Phe(7) orientation of alpha-MSH-ND, while maintaining the 'type I beta-turn'-like structure.

Shoulder MRI refinements: differentiation of rotator cuff tear from artifacts and tendonosis, and reassessment of normal findings

One of the difficulties with rotator cuff imaging lies in the normal variability of the tendon's signal. There may be intermediate signal present within the tendon because of magic-angle phenomenon, muscle and tendon fiber interdigitation, or tendinopathy related to degenerative changes or overuse injury. Partial and complete rotator cuff tears should be distinguishable from these causes of intermediate signal if water signal is reliably identified. This article reviews the important issue of distinguishing between rotator cuff tear and other causes of high signal in the rotator cuff, including artifacts and tendonosis. We include a review of the literature and a brief report of a study we conducted on 20 shoulders of 14 asymptomatic, young volunteers. In this study, the rotator cuff tendons were evaluated for abnormal signal at different TE values to determine at what TE the interpreters were able to confidently distinguish the high-signal intensity of a tear (water) from the intermediate signal intensity associated with artifact and tendinopathy. Readers were able to distinguish water and tendon signal in 70% to 100% of fast-spin echo (FSE) fat-saturated images with TE of 66, but there was interobserver variability at this TE, suggesting that it is less reliable than 88 ms in the identification of rotator cuff tears. By using FSE fat-saturated sequences with TE of 88 and fast spin echo inversion recovery (FSEIR) sequences, readers at all levels of experience were able to differentiate water signal intensity from tendon signal intensity in 100% of cases. Therefore, we suggest that either FSEIR images or FSE fat-saturated images with TE greater than 66 be used to facilitate the differentiation of fluid signal from intermediate increased signal intensity in rotator cuff imaging. Additionally, this article reviews the normal findings of shoulder magnetic resonance imaging (MRI) as revealed by the asymptomatic subjects included in our study, and assesses these findings in respect to previous publications. The normal features reviewed include the subacromion-subdeltoid (SA/SD) bursa, the biceps tendon sheath, the acromioclavicular (AC) joint, and the greater tuberosity of the humerus. A small amount of fluid was commonly seen in the SA/SD bursa, as well as the biceps tendon sheath. Subjective down-sloping of the acromion in the coronal plane, mild degenerative change of the AC joint, and undersurface spurring of the AC joint were uncommon in our normal subjects. Cystic change limited to the posterior aspect of the greater tuberosity was identified in 15% to 45% of shoulders.

The effect of imaging modality on patient management in the evaluation of pulmonary thromboembolism

A retrospective medical record review was performed to study the differences in clinical risk profiles and the relationships between test results versus management for suspected pulmonary thromboembolism (TE) in patients undergoing either radionuclide ventilation perfusion (V/Q) scans or pulmonary computed tomographic angiography (CTA), as the initial test. Data of 138 consecutive V/Q patients were compared with that of 149 consecutive CTA patients during equivalent 6-month intervals before and after the introduction of CTA. Information on risk factors, signs and symptoms, all diagnostic test results, and the relationships between the test results and ultimate physician management were collected and analyzed. V/Q results predicted physician management in all patients with high probability scans and 91% with normal to low probability scans. There were 35 patients with indeterminate V/Q scans--43% of these patients were managed without any other diagnostic test. CTA results predicted management in all patients with positive studies and 99% of patients with negative studies. In contrast to the V/Q cohort, only seven CTA studies were inconclusive--additional diagnostic tests determined management in all but one case. Compared with V/Q, CTA has fewer indeterminate results, is more directly reflective of management, and reduces the number of patients managed with inconclusive data.

Fatty acid binding protein 2 and insulin resistance

BACKGROUND

An A54T polymorphism of the fatty acid binding protein 2 (FABP2) gene was found to be associated with insulin resistance in nondiabetic Pima Indians. Design This is a cross-sectional study to examine the role of this polymorphism in insulin resistance in 71 healthy and normotensive Caucasian subjects with normal glucose tolerance. Insulin sensitivity (%S, ISI(M), ISI(S)) and beta-cell function (%B, dI/dG, 1stPHS, 2ndPHS) were estimated based on published models. Their genotypes were determined using a polymerase chain reaction-restriction fragment length polymorphism assay. The relationship between genotypes and phenotypes was examined.

RESULTS

After genotyping, we identified 34 AA, 32 AT and five TT subjects. The TT subjects were pooled together with the AT subjects during the analysis due to their low number. No difference was noted in gender distribution, clinical features, or fasting lipid profile between the two genotypic groups (AA vs. AT/TT). The AT/TT group had lower %S and ISI(S) than the AA group (P = 0.0118 and P = 0.0170, respectively). The difference in ISI(M) was marginal (P = 0.0544). However, no difference was noted in beta-cell function between the two groups. Multivariate analysis revealed that this polymorphism was an independent but modest determinant for %S (P = 0.0149), ISI(M) (P = 0.0489) and ISI(S) (P = 0.0175). It independently contributed 6.04% (95% CI, 0.02-20.53%), 4.28% (95% CI, 0.08-17.63%) and 4.94% (95% CI, 0.01-18.75%) of the variation of %S, ISI(M) and ISI(S), respectively.

CONCLUSIONS

We demonstrated that the A54T polymorphism at the FABP2 locus is a risk factor for insulin resistance in a Caucasian population.