Weight loss and retention in a commercial weight-loss program and the effect of corporate partnership.

BACKGROUND: No studies report whether improvements to commercial weight-loss programs affect retention and weight loss. Similarly, no studies report whether enrolling in a program through work (with a corporate partner) affects retention and weight loss. OBJECTIVES: To determine whether: (1) adding evidence-based improvements to a commercial weight-loss program increased retention and weight loss, (2) enrolling in a program through work increased retention and weight loss and (3) whether increased weight loss was because of longer retention. DESIGN, SETTING AND PARTICIPANTS: Data were collected on 60 164 adults who enrolled in Jenny Craig's Platinum Program over 1 year in 2001-2002. The program was subsequently renamed the Rewards Program and improved by increasing treatment personalization and including motivational interviewing. Data were then collected on 81 505 participants of the Rewards Program who enrolled during 2005 (2418 of these participants enrolled through their employer, but paid out-of-pocket). MEASUREMENTS: Retention (participants were considered active until >or=42 consecutive days were missed) and weight loss (percent of original body weight) from baseline to the last visit (data were evaluated through week 52) were determined. RESULTS: Alpha was set at 0.001. Mean (95% confidence interval (CI)) retention (weeks) was significantly higher among Rewards (19.5 (19.4-19.6)) compared with Platinum (16.3 (16.2-16.4)) participants, and Rewards Corporate (25.9 (25.0-26.8)) compared with Noncorporate (21.9 (21.7-22.1)) participants. Modified intent-to-treat analyses indicated that mean (95% CI) percent weight loss was significantly larger among Rewards (6.36 (6.32-6.40)) compared with Platinum (5.45 (5.41-5.49)) participants, and Rewards Corporate (7.16 (6.92-7.40)) compared with Noncorporate (6.20 (6.16-6.24)) participants, with and without adjustment for baseline participant characteristics. In all cases, greater weight loss was secondary to longer retention. LIMITATIONS: The study was not a randomized controlled trial, rather, a translational effectiveness study. CONCLUSIONS: Improvements to a commercial program and enrolling through a corporate partner are associated with greater weight loss that is because of improved retention.

Complex effects of naturally occurring mutations in the JAK3 pseudokinase domain: evidence for interactions between the kinase and pseudokinase domains.

The structure of Janus kinases (JAKs) is unique among protein tyrosine kinases in having tandem, nonidentical kinase and pseudokinase domains. Despite its conservation in evolution, however, the function of the pseudokinase domain remains poorly understood. Lack of JAK3 expression results in severe combined immunodeficiency (SCID). In this study, we analyze two SCID patients with mutations in the JAK3 pseudokinase domain, which allows for protein expression but disrupts the regulation of the kinase activity. Specifically, these mutant forms of JAK3 had undetectable kinase activity in vitro but were hyperphosphorylated both in patients' Epstein-Barr virus-transformed B cells and when overexpressed in COS7 cells. Moreover, reconstitution of cells with these mutants demonstrated that, although they were constitutively phosphorylated basally, they were unable to transmit cytokine-dependent signals. Further analysis showed that the isolated catalytic domain of JAK3 was functional whereas either the addition of the pseudokinase domain or its deletion from the full-length molecule reduced catalytic activity. Through coimmunoprecipitation of the isolated pseudokinase domain with the isolated catalytic domain, we provide the first evidence that these two domains interact. Furthermore, whereas the wild-type pseudokinase domain modestly inhibited kinase domain-mediated STAT5 phosphorylation, the patient-derived mutants markedly inhibited this phosphorylation. We thus conclude that the JAK3 pseudokinase domain is essential for JAK3 function by regulating its catalytic activity and autophosphorylation. We propose a model in which this occurs via intramolecular interaction with the kinase domain and that increased inhibition of kinase activity by the pseudokinase domain likely contributes to the disease pathogenesis in these two patients.

Renal accumulation of circulating angiotensin II in angiotensin II-infused rats.

Previous studies have demonstrated that low-dose angiotensin II (Ang II) infusion for 14 days mimics two-kidney, one clip Goldblatt hypertension and increases intrarenal Ang II levels. The objective of the present study was to determine whether the augmented intrarenal Ang II is due to intrarenal accumulation of the infused Ang II and/or to an increase in intrarenal formation of endogenous Ang II. Male Sprague-Dawley rats were uninephrectomized and divided into three groups: control (N=6), those infused with [Ile5]Ang II (endogenous form) (N=6), and those infused with [Val5]Ang II (n=8). [Ile5]Ang II or [Val5]Ang II was infused at 40 ng/min via an osmotic minipump implanted subcutaneously. By day 12, systolic blood pressure increased significantly in both [Val5]Ang II-infused rats (197 +/- 7 mm Hg) and [Ile5]Ang II-infused rats (173 +/- 3 mm Hg). Blood and kidney samples were harvested, subjected to high-performance liquid chromatography to separate [Val5]Ang II from [Ile5]Ang II, and then measured by radioimmunoassay. Plasma renin activity was markedly suppressed in both [Ile5]Ang II- and [Val5]Ang II-infused rats. Plasma Ang II levels were elevated in rats infused with both [Ile5]Ang II (121 +/- 24 fmol/mL) and [Val5]Ang II (119 +/- 14 fmol/mL) compared with controls (69 +/- 15 fmol/mL). Both [Ile5]Ang II- and [Val5]Ang II-infused rats exhibited an enhancement of total intrarenal Ang II. Only [Ile5]Ang II (358 +/- 53 fmol/g) was detected in the kidneys of rats infused with -Ile5-Ang II. In [Val5]Ang II-infused rats, a significant portion of total renal Ang II (371 +/- 57 fmol/g) was in the form of [Val5]Ang II (256 +/- 44 fmol/g). Renal [Ile5]Ang II levels were maintained in the [Val5]Ang II-infused rats (116 +/- 15 fmol/g) compared with control rats (116 +/- 11 fmol/g) despite marked suppression of renin release. These results support the hypothesis that infused circulating ANG II is bound to receptor or taken up intrarenally in a manner that protects against degradation.

Receptor-mediated intrarenal angiotensin II augmentation in angiotensin II-infused rats.

Chronic low-dose angiotensin II (Ang II) infusion for 13 days mimics two-kidney, one clip Goldblatt hypertension and increase intrarenal Ang II levels. We performed studies to determine the time course for the enhancement of intrarenal Ang II levels and whether the increased intrarenal Ang II is a tissue-specific event and requires a receptor-mediated step. Male Sprague-Dawley rats were uninephrectomized, and either vehicle or Ang II (40 ng/min) was infused via a subcutaneous osmotic minipump. Plasma and renal Ang II levels were measured 3, 7, 10, and 13 days after minipump implantation. Compared with controls (126 +/- 2 mm Hg), systolic pressure in Ang II-infused rats exhibited a detectable increase by day 6 (146 +/- 2 mm Hg) and continued to increase to 189 +/- 5 mm Hg by day 12. Plasma Ang II levels were elevated by day 3, whereas intrarenal Ang II levels were not significantly elevated until 10 days of Ang II infusion. Renal injury characterized by focal and segmental glomerulosclerosis was evident after 13 days of Ang II infusion. Losartan (30 mg/kg per day) prevented the development of hypertension in the Ang II-infused rats for the duration of the infusion period (125 +/- 1 mm Hg) and reduced the degree of glomerular injury. Plasma renin activity was suppressed in the Ang II-infused group but was elevated markedly in both losartan-treated groups. Plasma Ang II levels were elevated in the Ang II-infused rats and were even higher during losartan treatment. Intrarenal Ang II levels were enhanced significantly (354 +/- 60 versus 164 +/- 23 fmol/g) in the Ang II-infused rats. However, losartan treatment prevented the augmentation of intrarenal Ang II caused by Ang II infusion. Heart and adrenal Ang II levels were not significantly increased in the Ang II-infused rats but were significantly elevated during losartan treatment. These results suggest that the tissue-specific elevations of intrarenal Ang II levels caused by chronic Ang II infusion are mediated by angiotensin type 1 receptor activation, which leads to either receptor-mediated internalization of Ang II, enhancement of intrarenal Ang II formation, or both.

Plasma renin activity and metabolic clearance rate of angiotensin II in the unstressed aging rat.

We conducted studies in conscious chronically catheterized, trained young (3-5 months) and old (18-20 months) rats to assess the impact of aging on baseline renin activity (PRA) and metabolic clearance rate (MCR) of angiotensin II (ANG II). We observed that under unstressed conditions the baseline values of PRA and plasma ANG II were no different in young versus old rats (1.8 +/- 0.2 versus 1.5 +/- 0.2 ng Al/ml/h and 18 +/- 3 versus 15 +/- 2 fmol/ml, respectively). Values of PRA in the present study were similar to those reported by others for old rats, but our young rat values were lower than usually reported. This probably reflects our use of an unstressed preparation. We also observed a blunted increase in PRA in old rats in response to acute converting enzyme inhibition. Overall, our observations suggest that old rats may lose their ability to increase PRA in response to acute stimuli, including perhaps, the stress of blood drawing in emotionally or surgically stressed preparations. We also observed that the MCR of ANG II increased with age, despite similar baseline plasma ANG II concentrations in young and old. This suggests that with aging, an increase occurs in the rate of synthesis of ANG II. These results emphasize the importance of establishing true baseline values for indices of the renin-ANG II system in aging.

Renal uptake of circulating angiotensin II in Val5-angiotensin II infused rats is mediated by AT1 receptor.

Previous studies have demonstrated that augmentation of intrarenal angiotensin II (ANG II) levels during ANG II induced hypertension involves both endogenous formation and accumulation of circulating ANG II. The present work extends these findings and determines whether accumulation of infused ANG II in the kidney requires AT1 receptor activation by using Val5-ANG II as the infused peptide. Male Sprague-Dawley rats were uninephrectomized and divided into three groups: control (n = 6), Val5-ANG II (exogenous form) infused (n = 8), and Val5-ANG II infused rats treated with losartan (n = 8). Val5-ANG II, which has the same biological and immunoreactive properties as endogenous ANG II, was infused at 40 ng/min via an osmotic minipump implanted subcutaneously. By day 12, systolic blood pressure (SBP) increased significantly in Val5-ANG II infused rats (197 +/- 7 mm Hg). As previously shown, the development of hypertension in ANG II infused rats was prevented by losartan treatment. Blood and kidney samples were harvested, subjected to HPLC to separate Val5-ANG II (exogenous) from Ile5-ANG II (endogenous) and the fractions were measured by radioimmunoassay. In the Val5-ANG II infused rats treated with losartan, total plasma ANG II levels were elevated to a greater extent than in rats not treated with losartan (289 +/- 20 v 119 +/- 14 fmol/mL). However, losartan markedly decreased by 88% the enhancement of intrarenal Val5-ANG II content that occurred in the rats infused with Val5-ANG II alone. These results demonstrate that AT1 receptor blockade markedly reduces the intrarenal uptake of circulating ANG II that occurs in ANG II induced hypertension.

Dietary Na and ACE inhibition effects on renal tissue angiotensin I and II and ACE activity in rats.

This study was designed to improve and validate methods for the accurate and consistent quantitation of angiotensin (ANG) I and II levels in rat kidney and to determine the effects on renal ANG I and II of changes in dietary sodium intake and ANG-converting enzyme (ACE) inhibition. Kidneys from pentobarbital-anesthetized rats were rapidly removed and homogenized in methanol before extraction and purification of ANG peptides by solid-phase extraction and high-performance liquid chromatography (HPLC). Recoveries of 125I-ANG I and II were greater than 80%. Reversed-phase HPLC of the partially purified methanol extract showed that greater than 75% of the ANG I- and greater than 82% of the ANG II-like immunoreactivity coeluted with ANG I and II, respectively. Dietary sodium deprivation (0.003 meq/g) and excess (1.34 meq/g) for 7 days significantly (P less than 0.01) increased and decreased renal ANG I (296 +/- 30 and 82.6 +/- 15.8 vs. 161 +/- 18 fmol/g) and ANG II (216 +/- 16 and 45.6 +/- 11.8 vs. 98 +/- 16 fmol/g) contents, respectively. Plasma ANG I and II levels showed similar changes. ACE activity was significantly upregulated by sodium deprivation in both kidney (44% increase) and plasma (30% increase). In rats fed normal chow, infusion of enalaprilat for 1 h abolished plasma ACE activity but decreased renal ACE activity by only 58%. ACE inhibition increased renal and plasma ANG I levels 2.8- and 12-fold, respectively, and decreased renal and plasma ANG II levels 75-78%.(ABSTRACT TRUNCATED AT 250 WORDS)

Tubular fluid concentrations and kidney contents of angiotensins I and II in anesthetized rats.

Previous micropuncture studies have reported nanomolar concentrations of angiotensin II in proximal tubular fluid and have indicated that angiotensin II or a precursor may be secreted into the tubular lumen. Further experiments were performed to determine if proximal tubular fluid angiotensin I concentrations are also greater than plasma and kidney levels and to estimate the degree of intrarenal compartmentalization of the angiotensin peptides. Free-flow proximal tubular fluid samples were collected in micropipets and were pooled for each animal. At the end of each experiment, a blood sample was collected and the micropunctured left kidney was harvested and homogenized in methanol. The angiotensin I concentration in proximal tubular fluid samples averaged 6.1 +/- 1.2 pmol/mL, whereas the angiotensin II concentration averaged 8.1 +/- 1.6 pmol/mL (N = 13). HPLC analysis of a separate sample pooled from collections in five rats indicated that the immunoreactive angiotensin I and angiotensin II primarily represented authentic angiotensin I and II. Plasma concentrations of angiotensin I and angiotensin II averaged 0.39 +/- 0.09 and 0.15 +/- 0.03 pmol/mL, respectively. The kidney contents of angiotensin I and angiotensin II were 1.28 +/- 0.24 and 0.97 +/- 0.17 pmol/g of kidney, respectively. These findings indicate that proximal tubular fluid contains nanomolar concentrations of angiotensin I as well as angiotensin II. These high tubular fluid concentrations, which greatly exceed the plasma and kidney levels, likely reflect net secretion of the angiotensin peptides by proximal tubule cells.(ABSTRACT TRUNCATED AT 250 WORDS)

The amino terminus of JAK3 is necessary and sufficient for binding to the common gamma chain and confers the ability to transmit interleukin 2-mediated signals.

JAK3 is a protein tyrosine kinase that specifically associates with the common gamma chain (gammac), a shared subunit of receptors for interleukin (IL) 2, 4, 7, 9, and 15. Patients deficient in either JAK3 or gammac presented with virtually identical forms of severe combined immunodeficiency (SCID), underscoring the importance of the JAK3-gammac interaction. Despite the key roles of JAK3 and gammac in lymphocytic development and function, the molecular basis of this interaction remains poorly understood. In this study, we have characterized the regions of JAK3 involved in gammac association. By developing a number of chimeric JAK3-JAK2 constructs, we show that the binding specificity to gammac can be conferred to JAK2 by transferring the N-terminal domains of JAK3. Moreover, those JAK3-JAK2 chimeras capable of binding gammac were also capable of reconstituting IL-2 signaling as measured by inducible phosphorylation of the chimeric JAK3-JAK2 protein, JAK1, the IL-2 receptor beta chain, and signal transducer and activator of transcription 5A. Subsequent deletion analyses of JAK3 have identified the N-terminal JH7-6 domains as a minimal region sufficient for gammac association. Furthermore, expression of the mutant containing only the JH7-6 domains effectively competed with full-length JAK3 for binding to gammac. We conclude that the JH7-6 domains of JAK3 are necessary and sufficient for gammac association. These studies offer clues toward a broader understanding of JAK-mediated cytokine signaling and may provide a target for the development of novel therapeutic modalities in immunologically mediated diseases.