Citations

Abstract Background: The ratio of plasma aldosterone concentration to plasma renin activity (PRA) is considered the screening test of choice for primary aldosteronism. Uncertainty exists, however, regarding its diagnostic accuracy and the effects of antihypertensive drugs and dietary sodium balance on test characteristics. Methods: We measured PRA and aldosterone in 118 white adults [71 men and 47 women; mean (SD) age, 51 (7) years] with previously diagnosed essential hypertension. Measurements were made while individuals were on antihypertensive drug therapy, after a 2-week drug-free period, after 4 days of dietary sodium loading, and after acute furosemide diuresis. We measured 24-h urine aldosterone excretion and PRA on the 4th day of dietary sodium loading to establish the diagnosis of primary aldosteronism. ROC curves were constructed for ratios measured under each clinical condition, and likelihood ratios were determined for individuals on or off antihypertensive drug therapy. Results: Fifteen patients [13%; 95% confidence interval (CI), 7–20%] met the reference standard for primary aldosteronism. The mean (SD) areas under the ROC curves did not differ significantly across conditions of measurement [range, 0.80 (0.10) to 0.85 (0.04); P = 0.72]. When measured on and off antihypertensive drug therapy, the 95% CIs for the optimum cutpoint for the ratio overlapped. Point estimates of sensitivity on and off therapy were 73% (95% CI, 50–96%) and 87% (70–100%), respectively, and specificities were 74% (65–83%) and 75% (66–84%). Under either condition, increased ratios were associated with 2.4- to 13-fold increases of posttest odds above pretest odds. Conclusions: The aldosterone:PRA ratio provides only fair diagnostic accuracy in screening for primary aldosteronism, but concomitant antihypertensive drug therapy or acute variation in dietary sodium balance does not adversely affect test accuracy. Reporting of likelihood ratios associated with ranges of values of the aldosterone:PRA ratio, rather than use of a single “optimum” cutpoint, may enhance the usefulness of the test.

AbstractMultiple myeloma (MM) is a B-lineage malignancy characterized by diverse genetic subtypes and clinical outcomes. The recurrent immunoglobulin heavy chain (IgH) switch translocation, t(4;14)(p16;q32), is associated with poor outcome, though the mechanism is unclear. Quantitative reverse-transcription–polymerase chain reaction (RT-PCR) for proposed target genes on a panel of myeloma cell lines and purified plasma cells showed that only transcripts originating from the WHSC1/MMSET/NSD2 gene are uniformly dysregulated in all t(4;14)POS patients. The different transcripts detected, multiple myeloma SET domain containing protein (MMSET I), MMSET II, Exon 4a/MMSET III, and response element II binding protein (RE-IIBP), are produced by alternative splicing and alternative transcription initiation events. Translation of the various transcripts, including those from major breakpoint region 4-2 (MB4-2) and MB4-3 breakpoint variants, was confirmed by transient transfection and immunoblotting. Green fluorescent protein (GFP)–tagged MMSET I and II, corresponding to proteins expressed in MB4-1 patients, localized to the nucleus but not nucleoli, whereas the MB4-2 and MB4-3 proteins concentrate in nucleoli. Cloning and localization of the Exon 4a/MMSET III splice variant, which contains the protein segment lost in the MB4-2 variant, identified a novel protein domain that prevents nucleolar localization. Kinetic studies using photobleaching suggest that the breakpoint variants are functionally distinct from wild-type proteins. In contrast, RE-IIBP is universally dysregulated and also potentially functional in all t(4;14)POS patients irrespective of fibroblast growth factor receptor 3 (FGFR3) expression or breakpoint type.

Objective— Intima-media remodeling, as frequently assessed by changes in the external elastic lamina-to-lumen area (EELLA), is well-described in coronary artery disease in contrast to adventitial remodeling, especially in the early disease stage. Method and Results— Female domestic pigs were randomized to one of the following 12-week treatment groups: normal diet (N; n=6), high-cholesterol diet (HC; n=6), or renovascular hypertension (HT; n=4). Low-density lipoprotein (LDL) cholesterol serum concentration was higher in HC than in N and HT (395.5±106 versus 38.6±14 and 37.2±6.8 mg/dL; P <0.05 for both). Mean arterial pressure was higher in HT than in N and HC (141.3±21 versus 107.4±8.9 and 109.4±7.8 mm Hg; P <0.05 for both). EELLA ratio, as assessed by morphometry, was similar in N, HC, and HTN (1.03±0.32 versus 0.95±0.29 and 1.01±0.09; P <0.05 for both). Coronary vasa vasorum density, as assessed by 3-dimensional micro-computed tomography, was higher in HC than in N and HT (3.4±1.0 versus 1.9±0.3 and 2.0±1.2; P <0.05 for both). In contrast, immunostaining showed a higher collagen III content and the presence of adventitial myofibroblasts in HT compared with N and HC. Conclusions— The current study suggests that adventitial remodeling precedes intima and media remodeling of coronary arteries early after exposure to hypercholesterolemia and hypertension, with distinct qualitative differences between them.

Obesity occurs when energy intake exceeds energy expenditure. Humans expend energy through purposeful exercise and through changes in posture and movement that are associated with the routines of daily life [called nonexercise activity thermogenesis (NEAT)]. To examine NEAT's role in obesity, we recruited 10 lean and 10 mildly obese sedentary volunteers and measured their body postures and movements every half-second for 10 days. Obese individuals were seated, on average, 2 hours longer per day than lean individuals. Posture allocation did not change when the obese individuals lost weight or when lean individuals gained weight, suggesting that it is biologically determined. If obese individuals adopted the NEAT-enhanced behaviors of their lean counterparts, they might expend an additional 350 calories (kcal) per day.

Forkhead transcription factors FOXO1 (FKHR), FOXO3a (FKHRL1), and FOXO4 (AFX) play a pivotal role in tumor suppression by inducing growth arrest and apoptosis. Loss of function of these factors due to phosphorylation and proteasomal degradation has been implicated in cell transformation and malignancy. However, the ubiquitin ligase necessary for the ubiquitination of the FOXO factors and the relevance of this regulation to tumorigenesis have not been characterized. Here we demonstrate that Skp2, an oncogenic subunit of the Skp1/Cul1/F-box protein ubiquitin complex, interacts with, ubiquitinates, and promotes the degradation of FOXO1. This effect of Skp2 requires Akt-specific phosphorylation of FOXO1 at Ser-256. Moreover, expression of Skp2 inhibits transactivation of FOXO1 and abolishes the inhibitory effect of FOXO1 on cell proliferation and survival. Furthermore, expression of the FOXO1 protein is lost in a mouse lymphoma model, where Skp2 is overexpressed. These data suggest that the Skp2-promoted proteolysis of FOXO1 plays a key role in tumorigenesis.

Using quantitative light microscopy and a modified immunoelectron microscopic technique, we have characterized the entry pathway of the cholera toxin binding subunit (CTB) in primary embryonic fibroblasts. CTB trafficking to the Golgi complex was identical in caveolin-1null (Cav1−/−) mouse embryonic fibroblasts (MEFs) and wild-type (WT) MEFs. CTB entry in the Cav1−/− MEFs was predominantly clathrin and dynamin independent but relatively cholesterol dependent. Immunoelectron microscopy was used to quantify budded and surface-connected caveolae and to identify noncaveolar endocytic vehicles. In WT MEFs, a small fraction of the total Cav1-positive structures were shown to bud from the plasma membrane (2% per minute), and budding increased upon okadaic acid or lactosyl ceramide treatment. However, the major carriers involved in initial entry of CTB were identified as uncoated tubular or ring-shaped structures. These carriers contained GPI-anchored proteins and fluid phase markers and represented the major vehicles mediating CTB uptake in both WT and caveolae-null cells.