Objective-We sought to evaluate the influence of streptozotocin (STZ)-induced diabetes on renal outer medullary pO 2 and blood flow by invasive microprobes and to demonstrate feasibility that blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) can monitor these changes.Materials and Methods-A total of 60 Wistar-Furth rats were used. Diabetes was induced by STZ in 48. Animals were divided into OxyLite group (n = 30) and BOLD MRI groups (n = 30) each with a 5 subgroups of 6 animals: control and 2, 5, 14, and 28 days after induction of diabetes. Outer renal medullary oxygen tension and blood flow were measured by the combined OxyLite/OxyFlo probes. Results-BothOxyLite and BOLD MRI showed a significant increase in the renal hypoxia levels after STZ at all time points. However, no changes were observed in the outer renal medullary oxygen tension and blood flow between diabetic and control groups.Conclusions-These preliminary results suggest that hypoxic changes can be detected as early as 2 days in rat kidneys with diabetes by BOLD MRI and that these early changes are not dependent on blood flow.

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Purpose:To estimate the reproducibility of BOLD MRI measurements in the evaluation of intrarenal oxygenation levels. Materials and Methods:In this study, the reproducibility of semiquantitative BOLD MRI measurements performed on a 1.5 T scanner with a multiple gradient-echo sequence in the renal medulla and cortex, and their response to furosemide and waterload, were assessed in eight healthy young subjects (25.6 Ϯ 4.1 years). Each subject underwent an identical experimental procedure on two separate days.Results: Renal R* 2 measurements were shown to be reproducible within ϳ12% from day to day based on a coefficient of variance (CV) analysis. The changes in R* 2 (⌬R * 2 ) following administration of furosemide were statistically significant, as shown by ANOVA and a paired Student's t-test, and were deemed reliable based on the reliable change index (RCI). However, ⌬R* 2 values following waterload were not statistically significant, and were not deemed reliable.Conclusion: R* 2 measurements were reproducible over 270 days within 12%. Furosemide produced a significant and reliable change (ϳ30%), and the magnitude of change (5.7 s Ϫ1) was reproducible and consistent with our previous data. The response to waterload, however, did not reach statistical significance, and the magnitude did not reach the level that we had previously reported.

Introduction Chronic kidney disease (CKD) is known to be associated with reduced renal blood flow. However, data to-date in humans is limited. Methods In this study, non-invasive arterial spin labeling (ASL) MRI data was acquired in 33 patients with diabetes and stage-3 CKD, and 30 healthy controls. Results A significantly lower renal blood flow both in cortex (108.4±36.4 vs. 207.3±41.8; p<0.001, d=2.52) and medulla (23.2±8.9 vs. 42.6±15.8; p<0.001, d=1.5) was observed. Both cortical (ρ=0.67, p<0.001) and medullary (ρ=0.62, p<0.001) blood flow were correlated with eGFR, and cortical blood flow was found to be confounded by age and BMI. However, in a subset of subjects that were matched for age and BMI (n=6), the differences between CKD and control subjects remained significant both in cortex (107.4±42.8 vs. 187.51±20.44; p=0.002) and medulla (15.43±8.43 vs. 39.18±11.13; p=0.002). A threshold value to separate healthy and CKD was estimated to be Cor_BF=142.9 and Med_BF=24.1. Conclusion These results support the use of ASL in the evaluation of renal blood flow in patients with moderate level of CKD. Whether these measurements can identify subjects at risk of progressive CKD requires further longitudinal follow-up.

Fish demand patterns in nine Asian countries were investigated using a multistage budgeting framework allowing a disaggregated approach to analysing fish consumption. This paper highlights the heterogeneity of fisheries products in terms of species, sources and cultural responses of consumers, factors that are important in fish demand under the Asian setting. Specifically, fish demand by income groups were compared to determine how the low-and high-income households respond to price and income changes. Results showed that the estimated price and income elasticities of all fish types included in the study were relatively more elastic among the poorer households.

In this report, we propose to enhance the hole injection efficiency by adjusting the barrier height of the p-type electron blocking layer (p-EBL) for ∼273 nm deep ultraviolet light-emitting diodes (DUV LEDs). The barrier height for the p-EBL is modified by employing a p-Al 0.60 Ga 0.40 N/ Al 0.50 Ga 0.50 N/p-Al 0.60 Ga 0.40 N structure, in which the very thin Al 0.50 Ga 0.50 N layer is able to achieve a high local hole concentration, which is very effective in reducing the effective barrier height of the p-EBL for holes. More importantly, besides the thermionic emission, such a p-EBL structure can also favor a strong intraband tunneling process for holes. As a result, we can obtain a more efficient hole injection into the quantum wells, leading to a remarkably improved optical power for the DUV LED with the proposed p-EBL architecture.

Higher magnetic field strength is beneficial for renal BOLD MRI studies. The cortico-medullary contrast on the R2* map was significantly improved at 3.0 T, with no evidence of increased bulk susceptibility artifacts. Baseline R2* and DeltaR2* in the renal medulla at 3.0 T were both significantly higher compared to our previously reported data obtained at 1.5 T.

Purpose: To examine whether the noninvasive technique of blood oxygenation level dependent magnetic resonance imaging (BOLD MRI) can detect changes in renal medullary oxygenation following administration of a nitric oxide (NO) synthase inhibitor, N G -nitro-L-arginine methyl ester (L-NAME). Hypertension is associated with endothelial dysfunction and is characterized by a lack of response to endothelial-dependent vasoactive substances, including nitric oxide synthase inhibitors. We hypothesized that the magnitude of the change would be reduced in the kidneys of hypertensive subjects relative to normal controls. Materials and Methods:To test this hypothesis, data were obtained in spontaneously hypertensive rats (SHR, n ϭ 6). Wistar-Kyoto rats (WKY, n ϭ 7) were used as normotensive controls. Results:As expected, WKY rats showed a significant response to L-NAME (R 2 * increasing from 23.6Ϯ1.5 Hz to 32.5Ϯ2.2 Hz, P Ͻ 0.05), while SHR exhibited a minimal change in medullary oxygenation (R 2 * measuring 31.9Ϯ2.8 Hz pre-and 35.5Ϯ2.2 Hz post-L-NAME). The baseline R 2 * in SHR is found to be comparable to post-L-NAME values in WKY rats, suggesting a basal deficiency of nitric oxide in SHR. Conclusion:Based on the differential effect of NO synthase inhibition on medullary oxygenation, BOLD MRI can distinguish hypertensive from normal kidney. Our results are consistent with previously reported observations using invasive methods.