Pilot Study of the Effects of High-Protein Meals During Hemodialysis on Intradialytic Hypotension in Patients Undergoing Maintenance Hemodialysis.

OBJECTIVE: Patients undergoing hemodialysis (HD) have high protein and energy requirements, and protein-energy wasting is common and associated with poor outcomes. Eating during dialysis may improve nutritional status by counteracting the catabolic effects of HD treatment; but eating during HD may be discouraged because of concerns of postprandial hypotension. However, little data are available to support this practice. In this study, we hypothesized that high-protein meals during HD do not lead to symptomatic intradialytic hypotension events. DESIGN: A 9-week, nonrandomized, parallel-arm study. SETTING: A single in-center HD clinic. SUBJECTS: Eighteen patients undergoing HD from 2 shifts completed the study. Patients were aged 62 ± 16 years with dialysis vintage of 3.4 ± 2.6 years. INTERVENTION: Patients in the intervention group (n = 9) undergoing HD received meals of ∼30 g protein and ∼1/3 daily recommended intakes of sodium, potassium, phosphorus, and fluid during dialysis for 25 consecutive HD sessions. The control group (n = 9) completed all aspects of the study including a visit by study personnel but were not given meals. The 25 consecutive sessions before the start of the intervention/control phase were used as a baseline comparison for each patient. MAIN OUTCOME MEASURE: Symptomatic hypotension event frequency. RESULTS: In the intervention arm, there were 19 symptomatic hypotension events in 5 patients prestudy and 18 events in 6 patients during the study. In the control arm, there were 16 events in 7 patients prestudy and 13 events in 7 patients during the study. Change in the frequency of symptomatic hypotension events from prestudy to during study was not different between groups (P = .71). There was no effect of meals on nutritional status, but patients reported positive attitudes toward receiving meals during dialysis. CONCLUSION: High-protein meals during HD did not increase symptomatic hypotension events. Larger, longer term studies are needed to confirm these results and evaluate whether high-protein meals on dialysis benefit nutritional status and clinical outcomes.

A Mediterranean-style eating pattern with lean, unprocessed red meat has cardiometabolic benefits for adults who are overweight or obese in a randomized, crossover, controlled feeding trial.

Background: A Mediterranean-style eating pattern (Mediterranean Pattern) is often described as being low in red meat. Research shows that lean, unprocessed red meat can be incorporated into healthy eating patterns to improve cardiometabolic disease (CMD) risk factors. Objective: We assessed the effects of consuming different amounts of lean, unprocessed red meat in a Mediterranean Pattern on CMD risk factors. We hypothesized that consuming a Mediterranean Pattern would improve CMD risk factors and that red meat intake would not influence these improvements. Design: In an investigator-blinded, randomized, crossover, controlled feeding trial, 41 subjects [mean ± SD age: 46 ± 2 y; mean ± SD body mass index (kg/m2): 30.5 ± 0.6] were provided with a Mediterranean Pattern for two 5-wk interventions separated by 4 wk of self-selected eating. The Mediterranean Patterns contained ∼500 g [typical US intake (Med-Red)] and ∼200 g [commonly recommended intake in heart-healthy eating patterns (Med-Control)] of lean, unprocessed beef or pork per week. Red meat intake was compensated by poultry and other protein-rich foods. Baseline and postintervention outcomes included fasting blood pressure, serum lipids, lipoproteins, glucose, insulin, and ambulatory blood pressure. The presented results were adjusted for age, sex, and body mass at each time point (P < 0.05). Results: Total cholesterol decreased, but greater reductions occurred with Med-Red than with Med-Control (-0.4 ± 0.1 and -0.2 ±0.1 mmol/L, respectively, intervention × time = 0.045]. Low-density lipoprotein decreased with Med-Red but was unchanged with Med-Control [-0.3 ± 0.1 and -0.1 ± 0.1 mmol/L, respectively, intervention × time = 0.038], whereas high-density lipoprotein (HDL) concentrations decreased nondifferentially [-0.1 ± 0.0 mmol/L]. Triglycerides, total cholesterol:HDL, glucose, and insulin did not change with either Med-Red or Med-Control. All blood pressure parameters improved, except during sleep, independent of the red meat intake amount. Conclusions: Adults who are overweight or moderately obese may improve multiple cardiometabolic disease risk factors by adopting a Mediterranean-style eating pattern with or without reductions in red meat intake when red meats are lean and unprocessed. This trial was registered at clinicaltrials.gov as NCT02573129.

Consuming Almonds vs. Isoenergetic Baked Food Does Not Differentially Influence Postprandial Appetite or Neural Reward Responses to Visual Food Stimuli.

Nuts have high energy and fat contents, but nut intake does not promote weight gain or obesity, which may be partially explained by their proposed high satiety value. The primary aim of this study was to assess the effects of consuming almonds versus a baked food on postprandial appetite and neural responses to visual food stimuli. Twenty-two adults (19 women and 3 men) with a BMI between 25 and 40 kg/m² completed the current study during a 12-week behavioral weight loss intervention. Participants consumed either 28 g of whole, lightly salted roasted almonds or a serving of a baked food with equivalent energy and macronutrient contents in random order on two testing days prior to and at the end of the intervention. Pre- and postprandial appetite ratings and functional magnetic resonance imaging scans were completed on all four testing days. Postprandial hunger, desire to eat, fullness, and neural responses to visual food stimuli were not different following consumption of almonds and the baked food, nor were they influenced by weight loss. These results support energy and macronutrient contents as principal determinants of postprandial appetite and do not support a unique satiety effect of almonds independent of these variables.

Effects of Higher Dietary Protein and Fiber Intakes at Breakfast on Postprandial Glucose, Insulin, and 24-h Interstitial Glucose in Overweight Adults.

Dietary protein and fiber independently influence insulin-mediated glucose control. However, potential additive effects are not well-known. Men and women (n = 20; age: 26 ± 5 years; body mass index: 26.1 ± 0.2 kg/m²; mean ± standard deviation) consumed normal protein and fiber (NPNF; NP = 12.5 g, NF = 2 g), normal protein and high fiber (NPHF; NP = 12.5 g, HF = 8 g), high protein and normal fiber (HPNF; HP = 25 g, NF = 2 g), or high protein and fiber (HPHF; HP = 25 g, HF = 8 g) breakfast treatments during four 2-week interventions in a randomized crossover fashion. On the last day of each intervention, meal tolerance tests were completed to assess postprandial (every 60 min for 240 min) serum glucose and insulin concentrations. Continuous glucose monitoring was used to measure 24-h interstitial glucose during five days of the second week of each intervention. Repeated-measures ANOVA was applied for data analyses. The HPHF treatment did not affect postprandial glucose and insulin responses or 24-h glucose total area under the curve (AUC). Higher fiber intake reduced 240-min insulin AUC. Doubling the amount of protein from 12.5 g to 25 g/meal and quadrupling fiber from 2 to 8 g/meal at breakfast was not an effective strategy for modulating insulin-mediated glucose responses in these young, overweight adults.

Effects of Dietary Protein and Fiber at Breakfast on Appetite, ad Libitum Energy Intake at Lunch, and Neural Responses to Visual Food Stimuli in Overweight Adults.

Increasing either protein or fiber at mealtimes has relatively modest effects on ingestive behavior. Whether protein and fiber have additive or interactive effects on ingestive behavior is not known. Fifteen overweight adults (5 female, 10 male; BMI: 27.1 ± 0.2 kg/m²; aged 26 ± 1 year) consumed four breakfast meals in a randomized crossover manner (normal protein (12 g) + normal fiber (2 g), normal protein (12 g) + high fiber (8 g), high protein (25 g) + normal fiber (2 g), high protein (25 g) + high fiber (8 g)). The amount of protein and fiber consumed at breakfast did not influence postprandial appetite or ad libitum energy intake at lunch. In the fasting-state, visual food stimuli elicited significant responses in the bilateral insula and amygdala and left orbitofrontal cortex. Contrary to our hypotheses, postprandial right insula responses were lower after consuming normal protein vs. high protein breakfasts. Postprandial responses in other a priori brain regions were not significantly influenced by protein or fiber intake at breakfast. In conclusion, these data do not support increasing dietary protein and fiber at breakfast as effective strategies for modulating neural reward processing and acute ingestive behavior in overweight adults.

Dietary Approaches to Stop Hypertension diet retains effectiveness to reduce blood pressure when lean pork is substituted for chicken and fish as the predominant source of protein.

BACKGROUND: Hypertension is a major, modifiable risk factor for cardiovascular and kidney disease and premature mortality that is improved by the DASH (Dietary Approaches to Stop Hypertension) diet. The DASH diet emphasizes increased consumption of fruit and vegetables, whole grains, low-fat dairy, nuts, and poultry and fish and reduced intakes of fats, red meats (including pork), sodium, and added sugars. OBJECTIVE: We sought to evaluate whether the consumption of lean pork compared with the consumption of chicken and fish as the predominant protein source in a DASH-style diet affected blood pressure (BP) control in men and women with elevated BP. DESIGN: In a randomized crossover study, 13 women and 6 men [mean ± SEM age: 61 ± 2 y; BMI (in kg/m²): 31.2 ± 1.4] with elevated BP [systolic blood pressure (SBP)/diastolic blood pressure (DBP): 130 ± 2/85 ± 2 mm Hg] consumed a DASH-style diet for two 6-wk controlled dietary interventions (with a 4-wk diet washout between interventions) with either lean pork [DASH diet with pork (DASH-P)] or chicken and fish [DASH diet with chicken and fish (DASH-CF), the control diet] as the major protein source (55% of total protein intake). SBP and DBP were measured manually and with a 24-h BP monitoring system on 3 d before and 3 d at the end of each diet intervention. RESULTS: Preintervention manual BP (DASH-P: 130/84 ± 2/1 mm Hg; DASH-CF: 129/84 ± 2/1 mg Hg) and postintervention manual BP (DASH-P: 122/79 ± 2/1 mm Hg; DASH-CF: 123/78 ± 3/1) were not different between the DASH-P and DASH-CF. Consumption of these DASH-style diets for 6 wk reduced all measures of BP (P < 0.05) with no differences in responses between the DASH-CF and DASH-P. CONCLUSION: The results indicate that adults with elevated BP may effectively incorporate lean pork into a DASH-style diet for BP reduction.

Formation of a human ß-cell population within pancreatic islets is set early in life.

CONTEXT: Insulin resistance can be compensated by increased functional pancreatic ß-cell mass; otherwise, diabetes ensues. Such compensation depends not only on environmental and genetic factors but also on the baseline ß-cell mass from which the expansion originates. OBJECTIVE: Little is known about assembly of a baseline ß-cell mass in humans. Here, we examined formation of ß-cell populations relative to other pancreatic islet cell types and associated neurons throughout the normal human lifespan. DESIGN AND METHODS: Human pancreatic sections derived from normal cadavers aged 24 wk premature to 72 yr were examined by immunofluorescence. Insulin, glucagon, and somatostatin were used as markers for ß-, α-, and δ-cells, respectively. Cytokeratin-19 marked ductal cells, Ki67 cell proliferation, and Tuj1 (neuronal class III ß-tubulin) marked neurons. RESULTS: Most ß-cell neogenesis was observed preterm with a burst of ß-cell proliferation peaking within the first 2 yr of life. Thereafter, little indication of ß-cell growth was observed. Postnatal proliferation of α- and δ-cells was rarely seen, but a wave of ductal cell proliferation was found mostly associated with exocrine cell expansion. The ß-cell to α-cell ratio doubled neonatally, reflecting increased growth of ß-cells, but during childhood, there was a 7-fold change in the ß-cell to δ-cell ratio, reflecting an additional loss of δ-cells. A close association of neurons to pancreatic islets was noted developmentally and retained throughout adulthood. Negligible neuronal association to exocrine pancreas was observed. CONCLUSION: Human baseline ß-cell population and appropriate association with other islet cell types is established before 5 yr of age.

Identification of adeno-associated viral vectors suitable for intestinal gene delivery and modulation of experimental colitis.

Effective gene transfer with sustained gene expression is an important adjunct to the study of intestinal inflammation and future therapy in inflammatory bowel disease. Recombinant adeno-associated virus (AAV) vectors are ideal for gene transfer and long-term transgene expression. The purpose of our study was to identify optimal AAV pseudotypes for transduction of the epithelium in the small intestine and colon, which could be used for studies in experimental colitis. The tropism and transduction efficiencies of AAV pseudotypes 1-10 were examined in murine small intestine and colon 8 wk after administration by real-time PCR and immunohistochemistry. The clinical and histopathological effects of IL-10-mediated intestinal transduction delivered by AAVrh10 were examined in the murine IL-10⁻/⁻ enterocolitis model. Serum IL-10 levels and IL-10 expression were followed by ELISA and real-time PCR, respectively. AAV pseudotypes 4, 7, 8, 9, and 10 demonstrated optimal intestinal transduction. Transgene expression was sustained 8 wk after administration and was frequently observed in enteroendocrine cells. Long-term IL-10 gene expression and serum IL-10 levels were observed following AAV transduction in an IL-10-/- model of enterocolitis. Animals treated with AAVrh10-IL-10 had lower disease activity index scores, higher colon weight-to-length ratios, and lower microscopic inflammation scores. This study identifies novel AAV pseudotypes with small intestine and colon tropism and sustained transgene expression capable of modulating mucosal inflammation in a murine model of enterocolitis.

Recombinant adeno-associated virus-mediated gene transfer for the potential therapy of adenosine deaminase-deficient severe combined immune deficiency.

Severe combined immune deficiency due to adenosine deaminase (ADA) deficiency is a rare, potentially fatal pediatric disease, which results from mutations within the ADA gene, leading to metabolic abnormalities and ultimately profound immunologic and nonimmunologic defects. In this study, recombinant adeno-associated virus (rAAV) vectors based on serotypes 1 and 9 were used to deliver a secretory version of the human ADA (hADA) gene to various tissues to promote immune reconstitution following enzyme expression in a mouse model of ADA deficiency. Here, we report that a single-stranded rAAV vector, pTR2-CB-Igκ-hADA, (1) facilitated successful gene delivery to multiple tissues, including heart, skeletal muscle, and kidney, (2) promoted ectopic expression of hADA, and (3) allowed enhanced serum-based enzyme activity over time. Moreover, the rAAV-hADA vector packaged in serotype 9 capsid drove partial, prolonged, and progressive immune reconstitution in ADA-deficient mice. Overview Summary Gene therapies for severe combined immune deficiency due to adenosine deaminase (ADA) deficiency (ADA-SCID) over two decades have exclusively involved retroviral vectors targeted to lymphocytes and hematopoietic progenitor cells. These groundbreaking gene therapies represented an unprecedented revolution in clinical medicine but in most cases did not fully correct the immune deficiency and came with the potential risk of insertional mutagenesis. Alternatively, recombinant adeno-associated virus (rAAV) vectors have gained attention as valuable tools for gene transfer, having demonstrated no pathogenicity in humans, minimal immunogenicity, long-term efficacy, ease of administration, and broad tissue tropism (Muzyczka, 1992 ; Flotte et al., 1993 ; Kessler et al., 1996 ; McCown et al., 1996 ; Lipkowitz et al., 1999 ; Marshall, 2001 ; Chen et al., 2003 ; Conlon and Flotte, 2004 ; Griffey et al., 2005 ; Pacak et al., 2006 ; Stone et al., 2008 ; Liu et al., 2009 ; Choi et al., 2010 ). Currently, rAAV vectors are being utilized in phase I/II clinical trials for cystic fibrosis, α-1 antitrypsin deficiency, Canavan's disease, Parkinson's disease, hemophilia, limb-girdle muscular dystrophy, arthritis, Batten's disease, and Leber's congenital amaurosis (Flotte et al., 1996 , 2004 ; Kay et al., 2000 ; Aitken et al., 2001 ; Wagner et al., 2002 ; Manno et al., 2003 ; Snyder and Francis, 2005 ; Maguire et al., 2008 ; Cideciyan et al., 2009 ). In this study, we present preclinical data to support the viability of an rAAV-based gene transfer strategy for cure of ADA-SCID. We report efficient transduction of a variety of postmitotic target tissues in vivo, subsequent human ADA (hADA) expression, and enhanced hADA secretion in tissues and blood, with increasing peripheral lymphocyte populations over time.

Proteasomes from structure to function: perspectives from Archaea.

Insight into the world of proteolysis has expanded considerably over the past decade. Energy-dependent proteases, such as the proteasome, are no longer viewed as nonspecific degradative enzymes associated solely with protein catabolism but are intimately involved in controlling biological processes that span life to death. The proteasome maintains this exquisite control by catalyzing the precisely timed and rapid turnover of key regulatory proteins. Proteasomes also interplay with chaperones to ensure protein quality and to readjust the composition of the proteome following stress. Archaea encode proteasomes that are highly related to those of eukaryotes in basic structure and function. Investigations of archaeal proteasomes coupled with those of eukaryotes has greatly facilitated our understanding of the molecular mechanisms that govern regulated protein degradation by this elaborate nanocompartmentalized machine.

Archaeal proteasomes and other regulatory proteases.

Numerous proteases have been shown to catalyze the precisely-timed and rapid turnover of key cellular proteins. Often these regulatory proteases are either energy-dependent or intramembrane-cleaving. In archaea, two different types of energy-dependent proteases have been characterized: 20S proteasomes associated with proteasome-activating nucleotidases and membrane-associated Lon proteases. Interestingly, homologs of all three mechanistic classes of intramembrane-cleaving proteases are widely distributed in archaea. Similar to their eucaryal and bacterial counterparts, members of these uncharacterized proteases might promote the controlled release of membrane-anchored regulatory proteins or liberate small peptide reporters and/or effectors that function in cell signaling.