Effects of Prolonged Energy Restriction and Dietary Protein on Muscle Protein Synthesis and Proteome Dynamics in Obese Zucker Rats

Objectives High protein (HP) diets during short-term energy restriction (ER) attenuate energy-mediated reductions in muscle protein synthesis (MPS). MPS-adaptive responses to HP diets during prolonged ER are not well described. This study examined the effects of prolonged ER and HP on MPS and the synthesis rates of numerous individual muscle proteins. Methods Female 6-wk-old obese Zucker (leprfa+/fa+, n = 48) rats were randomized to one of four diet groups for 10 weeks: ad libitum-standard protein (AL-SP; 14% protein), AL-HP (35% protein), ER-SP, and ER-HP (both fed 60% of intake of AL-SP). At the start of week 10, D2O was administered by intraperitoneal injection and isotopic equilibrium was maintained daily by providing D2O in drinking water. Rats were euthanized after 1 week of labeling, and mixed-MPS (gastrocnemius), absolute mixed-MPS (mixed-MPS x muscle protein content), proteome dynamics, and protein half-lives [rate/d (k) = –ln(1-f)/d, where f is mixed-MPS and t is time in days; t1/2 (days) = ln(2)/k] were quantified. Results Mixed-MPS was not altered by energy status and protein intake. Gastrocnemius mass was lower (P < 0.001) in ER-fed rats than AL-fed rats and higher (P = 0.034) for AL-HP than AL-SP. As a result, absolute mixed-MPS was lower (P < 0.005) in ER than AL, regardless of dietary protein. Absolute synthesis in 24 of 26 myofibrillar, 32 of 61 mitochondrial, and 55 of 60 cytoplasmic measured proteins were lower in ER than AL (P < 0.05), regardless of dietary protein. The difference in absolute synthesis of myofibrillar, mitochondrial, and cytoplasmic proteins due to ER compared to AL was 28%, 16%, and 27%, respectively. Comparison of HP and SP within each energy state revealed lower turnover rates and prolonged half-lives for a majority of measured muscle proteins in HP than in SP in both ER and AL conditions (P < 0.001). Conclusions Prolonged ER in obese Zucker rats exerted a strong suppressive effect on myofibrillar, mitochondrial, and cytoplasmic MPS, suggesting reduced protein accretion contributed to lower gastrocnemius mass in ER-fed rats. Lower turnover rates of most muscle proteins in HP-fed rats without reductions in protein pool size (i.e., tissue mass) suggests prolonged HP intake, independent of energy, may prolong muscle protein lifespan of in obese Zucker rats. Funding Sources Supported by USAMRDC; authors’ views not official U.S. Army or DoD policy.

Progettare la «Stimmung». Dialogo tra Quintus Miller e Armando Ruinelli

The architects Quintus Miller and Armando Ruinelli operate mainly in Switzerland and in particular in the Grisons area where they have carried out several projects thus facing the different issues affecting the requalification of landscape and of existing architecture in the valley and mountain context. The dialogue between the two architects highlights their design approach in relation to the historical, cultural and environmental peculiarities of this heritage. What emerges strongly is the need for the contemporary project to reinterpret the existing in order to identify and restore in each project the «Stimmung» intended as an absolute synthesis of all those elements that characterize a given place or a given architecture in time and space. From the architectural redevelopment of small buildings to the insertion of new volumes within historical fabrics, from the restoration of monuments to the expansion of historic structures, the narrated projects show a well-read approach towards the intervention on heritage allowing a critical reinterpretation of history, of memory and of the long lasting Alpine settlement processes.

Hegelian Phenomenology of Spirit and Boxing Fight

In the presented text the author points out to anthropological as well as axiological foundations of the boxing fight from the viewpoint of Hegel’s philosophy. In the genial idealist’s views it is possible to perceive the appreciation of the body, which constitutes a necessary basis for the man’s physical activity, for his work oriented towards the self-transformation and the transformation of the external world, as well as for rivalry and the hand-to-hand fight. While focusing our attention on the issue of rivalry and on the situation of the fight - and regarding it from the viewpoint of the master - slave theory (included in the phenomenology of spirit), it is possible to proclaim that even a conventionalised boxing fight - that is, restricted by cultural and sports rules of the game - has features of the fight to the death between two Hegelian forms of selfknowledge striving for self-affirmation and self-realisation. In the boxing fight, similarly as in the above mentioned Hegelian theory, a problem of work and of the development of the human individual (that is, of the subject, self-knowledge, the participant of the fight) appears. There appears also a prospect of death as a possible end of merciless rivalry. The fight revalues the human way in an important way, whereas the prospect for death, the awareness of its proximity, the feeling that its close and possible, saturates the life with additional values. It places the boxer, just like every subject fighting in a similar or a different way, on the path towards absolute abstraction - that is, it brings him closer to his self-fulfilment in the Absolute, to the absolute synthesis. The Hegelian viewpoint enables also to appreciate the boxing fight as a manifestation of low culture (being in contrast with high culture), to turn attention to the relations which - according to Hegel - take place between the Absolute and the man, as well as to show which place is occupied by the subject both in the process of the Absolute’s self-realisation and in the German thinker’s philosophical system. Independently of the dialectical, simultaneously pessimistic and optimistic overtone of considerations connected with the very boxing fight (regarding destruction and spiritualisation on a higher level), it is possible to perceive farreaching appreciation of the human individual in Hegel’s philosophy since the Absolute cannot make its own self-affirmation without the individual, without the human body, without the fight aimed at the destruction of the enemy and without the subjective consciousness and the collective consciousness which appear thanks to this fight. Thus, it is justified to suppose that the foundation of the whole Hegel’s philosophy is constituted by anthropology and that in the framework of this anthropology a special role is played by the fight and by work, which changes the subject and his(her) environment. Admittedly Hegel does not emphasise it explicitly, nevertheless his views (with their centre, which, according to Hegel himself and his interpreters, is constituted by the Absolute) have, as a matter of fact, an anthropocentric character and the main source of the subject’s development is the struggle which, irrespectively of its result, always primarily leads to the destruction or even to the death of one of the sides, just like in the boxing fight. However, it is also a germ of the positive re-orientation of the subject, the beginning and a continuation of that what the phenomenology of the spirit describes as a movement towards absolute abstraction.

Albumin synthesis in humans increases immediately following the administration of endotoxin

In order to investigate the immediate (i.e. within 3h) response of albumin synthesis to the administration of endotoxin, as a model of a moderate and well controlled catabolic insult, two measurements employing L-[2H5]phenylalanine were performed in 16 volunteers. One group (n = 8) received an intravenous injection of endotoxin (4ng/kg; lot EC-6) immediately after the first measurement of albumin synthesis, whereas the other group received saline. A second measurement was initiated 1h later. In the endotoxin group, the fractional synthesis rate of albumin was 6.9±0.6%/day (mean±S.D.) in the first measurement. In the second measurement, a significant increase was observed (9.6±1.2%/day; P<0.001). The corresponding values in the control group were were 6.6±0.6%/day and 7.0±0.6%/day respectively (not significant compared with first measurement and P<0.001 compared with the second measurement in the endotoxin group). The absolute synthesis rates of albumin were 148±35 and 201±49mg·kg-1·day-1 before and after endotoxin (P<0.01). In the control group, the corresponding values were 131±21 and 132±20mg·kg-1·day-1 (not significant compared with the first measurement and P<0.01 compared with the second measurement in the endotoxin group). In conclusion, these results indicate that albumin synthesis increases in the very early phase after a catabolic insult, as represented by the administration of endotoxin.

The response of liver albumin synthesis to infection in rats varies with the phase of the inflammatory process

To discriminate between the effects of infection and of anorexia associated with infection, liver albumin synthesis was measured in well-fed rats, in rats injected with live Escherichia coli and in pair-fed rats at different stages of the inflammatory response (1, 6 and 10 days after infection) using a large dose of l-[1-14C]valine. Albuminaemia and albumin mRNA levels were unchanged following food restriction. However, absolute albumin synthesis was decreased in pair-fed rats compared with control animals after 1 day of food restriction, and had returned to normal values by day 10 when food intake was restored. Infection was characterized by a decrease in the plasma albumin concentration (35%, 45% and 28% as compared with pair-fed rats at 1, 6 and 10 days after infection respectively). Albumin mRNA levels and relative albumin synthesis were reduced in infected rats as compared with both control and pair-fed animals at all stages of infection. However, during the early acute response, the albumin absolute synthesis rate was similar in infected rats and pair-fed rats, indicating no specific effect of infection at this stage. Later in the course of infection, the amount of albumin synthesized by the liver was lower in infected than in pair-fed rats, and hypoalbuminaemia was probably maintained due to a lack of stimulation of synthesis despite increased food intake.

Increased Albumin and Fibrinogen Synthesis in Hemodialysis Patients with Normal Nutritional Status

This study compared the rates of whole-body proteolysis and of albumin and fibrinogen synthesis of seven hemodialysis patients (HD) with those of seven normal matched control subjects (C). HD patients had a normal nutritional and inflammatory status and serum albumin levels >3.5 g/dl. Endogenous leucine flux, albumin and fibrinogen fractional synthesis rate (FSR), and absolute intravascular synthesis rate (ASR) of albumin and fibrinogen all were evaluated by a primed/continuous infusion of 5,5,5-D3-L-leucine. Plasma volume was determined by the Evans blue dye dilution method. Endogenous leucine flux was significantly increased in HD (2.64 ± 0.08 μmol/kg per min) compared with C (2.17 ± 0.07 μmol/kg per min,P< 0.05). Serum albumin concentrations were similar in HD and C. Plasma fibrinogen levels were significantly increased in HD compared with C (P< 0.05). Plasma volume was greater in HD than in C (P< 0.05). As a result, total intravascular pool of both albumin (141 ± 7versus114 ± 3 g/1.73 m2,P< 0.05) and fibrinogen (11.7 ± 1versus6.7 ± 0.5 g/1.73 m2,P< 0.05) were greater in HD than in C. Albumin FSR was not statistically different in HD and C. However, albumin ASR was significantly increased in HD than in C (13.7 ± 2versus10.3 ± 1 g/1.73 m2per d,P< 0.05). Similarly, FSR of fibrinogen did not differ in HD and C groups, whereas ASR of fibrinogen was significantly higher in HD than in C (3.31 ± 0.6versus1.94 ± 0.3 g/1.73 m2per d,P< 0.05). In summary, normoalbuminemic HD patients have an increased intravascular pool with a greater absolute synthesis rate of both albumin and fibrinogen and an increased rate of whole-body leucine flux.

Inhibition of liver protein synthesis during laparoscopic surgery

Previous studies have indicated that laparoscopic surgery is associated with a decline in liver protein synthesis. In this study, the fractional synthesis rate (FSR) of total liver protein and albumin was measured in patients undergoing elective laparoscopic cholecystectomy at different times after commencing the procedure ( n = 8 + 8). Liver biopsy specimens were taken after 15 min of surgery in an “early” group and after 49 min of surgery in a “late” group. The liver FSR was higher in the early group (24.1 ± 4.7%/day) compared with the late group (19.0 ± 2.8%/day, P < 0.02). The fractional and absolute synthesis rates of albumin were similar in the two groups, 6.4 ± 1.5 vs. 6.5 ± 1.0%/day and 97 ± 19 vs. 96 ± 18 mg ⋅ kg−1⋅ day−1for the early and late groups, respectively. It is concluded that laparoscopic surgery was accompanied by a decrease in total liver protein synthesis rate, which developed rapidly during surgery. In contrast, no change in the synthesis rate of albumin was apparent during the course of surgery.

Erythrocyte glutathione deficiency in symptom-free HIV infection is associated with decreased synthesis rate

Although several studies have documented intra- and extracellular glutathione (GSH) deficiency in asymptomatic human immunodeficiency virus (HIV) infection, the mechanisms responsible for the altered GSH homeostasis remain unknown. To determine whether decreased synthesis contributes to this alteration of GSH homeostasis, a primed-constant infusion of [2H2]glycine was used to measure the fractional and absolute rates of synthesis of GSH in five healthy and five symptom-free HIV-infected subjects before and after supplementation for 1 wk with N-acetylcysteine. The erythrocyte GSH concentration of the HIV-infected group was lower ( P < 0.01) than that of the control group (1.4 ± 0.16 vs. 2.4 ± 0.08 mmol/l). The smaller erythrocyte GSH pool of the HIV-infected group was associated with a significantly slower ( P < 0.01) absolute synthesis rate of GSH (1.15 ± 0.14 vs. 1.71 ± 0.15 mmol ⋅ l−1 ⋅ day−1) compared with controls. Cysteine supplementation elicited significant increases in both the absolute rate of synthesis and the concentration of erythrocyte GSH. These results suggest that the GSH deficiency of HIV infection is due in part to a reduced synthesis rate secondary to a shortage in cysteine availability.

Parenteral nutrition selectively decreases protein synthesis in the small intestine

We investigated the effects of an elemental diet fed parenterally or enterally on total mucosal protein and lactase phlorizin hydrolase (LPH) synthesis. Catheters were placed in the stomach, jugular vein, and carotid artery of 12 3-day-old pigs. Half of the animals were given an elemental regimen enterally and the other half parenterally. Six days later, animals were infused intravenously with [2H3]leucine for 6 h and killed, and the midjejunum of each animal was collected for analysis. The weight of the midjejunum was 8 ± 1.5 and 17 ± 1.6 g in parenterally fed and enterally fed piglets, respectively. LPH activities (μmol ⋅ min−1 ⋅ g protein−1) were significantly higher in parenterally vs. enterally fed piglets. Total small intestinal LPH activities were lower in parenterally vs. enterally fed animals. The abundance of LPH mRNA relative to elongation factor-1α mRNA was not different between groups. The fractional synthesis rate of total mucosal protein and LPH was significantly lower in parenterally fed animals (67 ± 7 and 66 ± 7%/day, respectively) than in enterally fed animals (96 ± 7 and 90 ± 6%/day, respectively). The absolute synthesis rate (the amount of protein synthesized per gram of mucosa) of total mucosal protein was significantly lower in parenterally fed than in enterally fed piglets. However, the absolute synthesis rate of LPH was unaffected by the route of nutrient administration. These results suggest that the small intestine partially compensates for the effects of parenteral feeding by maintaining the absolute synthesis rate of LPH at the same levels as in enterally fed animals.

Lactase phlorhizin hydrolase turnover in vivo in water-fed and colostrum-fed newborn pigs

We have estimated the synthesis rates in vivo of precursor and brush-border (BB) polypeptides of lactase phlorhizin hydrolase (LPH) in newborn pigs fed with water or colostrum for 24 h post partum. At the end of the feeding period, piglets were anaesthetized and infused intravenously for 3 h with l-[4-3H]-phenylalanine. Blood and jejunal samples were collected at timed intervals. The precursor and BB forms of LPH were isolated from jejunal mucosa by immunoprecipitation followed by SDS/PAGE, and their specific radioactivity in Phe determined. The kinetics of precursor and BB LPH labelling were analysed by using a linear compartmental model. Immunoisolated LPH protein consisted of five polypeptides [high-mannose LPH precursor (proLPHh), complex glycosylated LPH precursor (proLPHc), intermediate complex glycosylated LPH precursor (proLPHi) and two forms of BB LPH]. The fractional synthesis rate (Ks) of proLPHh and proLPHc (approx. 5%/min) were the same in the two groups but the absolute synthesis rate (in arbitrary units, min-1) of proLPHh in the colostrum-fed animals was twice that of the water-fed animals. The Ks values of proLPHi polypeptides were significantly different (water-fed, 3.89%/min; colostrum-fed, 1.6%/min), but the absolute synthesis rates did not differ. The Ks of BB LPH was not different between experimental treatment groups (on average 0.037%/min). However, the proportion of newly synthesized proLPHh processed to BB LPH was 48% lower in colostrum-fed than in water-fed animals. We conclude that in neonatal pigs, the ingestion of colostrum stimulates the synthesis of proLPHh but, at least temporarily, disrupts the processing of proLPH polypeptides to the BB enzyme.