Low protein

About: Low protein is a research topic. Over the lifetime, 8139 publications have been published within this topic receiving 213225 citations.

Early changes in serum concentrations of somatomedin-C induced by dietary protein deprivation in rats: contributions of growth hormone receptor and post-receptor defects.

Abstract: To define the mechanism(s) for the decrease of somatomedin concentrations in acute protein malnutrition, we have assessed the relationships between serum immunoreactive somatomedin-C/insulin-like growth factor-I (Sm-C/IGF-I), serum immunoreactive GH and total (MgCl2-treated homogenates) as well as free (water-treated homogenates) liver somatogenic (GH) binding sites in growing rats fed a 5% protein diet for 12 or 24 h and given an s.c. injection(s) of rat GH (rGH) or saline. Control rats were fed a 15% protein diet and injected with rGH or saline. After 12 and 24 h of protein restriction, body weight was 6.9 and 8.2% below controls respectively (P less than 0.001), while Sm-C/IGF-I concentrations were reduced by 58 and 66% respectively (P less than 0.001 vs controls). Serum GH concentrations were not affected by the low protein intake. Furthermore, injection(s) of 50-100 micrograms rGH failed to raise serum Sm-C/IGF-I concentrations in the protein-deficient animals. The number of total and free GH-binding sites was modestly (15-20%) decreased at 12 and 24 h in the protein-restricted rats. Serum Sm-C/IGF-I concentrations correlated weakly with free and total binding sites (r = 0.48 and 0.38 respectively). Affinity constants of GH-binding sites were not changed by protein restriction. The profound reduction in Sm-C/IGF-I concentrations within a few hours of beginning protein restriction, and the discordance between this reduction and the small decline in somatogenic binding sites, suggests that, in addition to GH receptor loss, a postreceptor defect may participate in the GH resistance occurring in the early stages of protein deficiency.

Dietary intake and olfactory function in patients with newly diagnosed Parkinson's disease: a case-control study

Abstract: OBJECTIVE: To evaluate energy and nutrient intake in newly diagnosed Parkinson's disease (PD) patients and association between olfaction and nutrient density of the diet. DESIGN: Baseline data from a prospective cohort study. SUBJECTS: Eighty-seven patients and 28 age- and sex-matched controls participated in the study. METHODS: Dietary intake was assessed by using 3-day dietary records and 24-hour dietary recalls. The Brief Smell Identification Test (B-SIT) was used to test olfaction. RESULTS: Patients, compared with controls, had lower intake of polyunsaturated fatty acids (P = 0.024) and a higher intake of carbohydrates (P = 0.027) in energy percent (E%). Lower intake of protein (E%) (P = 0.045), and a low nutrient density of folate (P = 0.022), magnesium (P = 0.012), and phosphorus (P = 0.029) were associated with lower B-SIT score in both patients and controls. PD patients had a lower B-SIT score than controls (P < 0.001). CONCLUSION: The results indicate a higher relative contribution of energy from carbohydrates in PD patients. An association between low protein, folate, magnesium, and phosphorus density of the diet and olfaction was seen in the whole population.

Association of partially-folded intermediates of staphylococcal nuclease induces structure and stability.

Abstract: Staphylococcal nuclease forms three different partially-folded intermediates at low pH in the presence of low to moderate concentration of anions, differing in the amount of secondary structure, globularity, stability, and compactness. Although these intermediates are monomeric at low protein concentration (< or =0.25 mg/mL), increasing concentrations of protein result in the formation of dimers and soluble oligomers, ultimately leading to larger insoluble aggregates. Unexpectedly, increasing protein concentration not only led to association, but also to increased structure of the intermediates. The secondary structure, stability, and globularity of the two less-ordered partially-folded intermediates (A1 and A2) were substantially increased upon association, suggesting that aggregation induces structure. An excellent correlation was found between degree of association and amount of structure measured by different techniques, including circular dichroism, fluorescence, Fourier transform infrared spectroscopy (FTIR), and small-angle X-ray scattering. The associated states were also substantially more stable toward urea denaturation than the monomeric forms. A mechanism is proposed, in which the observed association of monomeric intermediates involves intermolecular interactions which correspond to those found intramolecularly in normal folding to the native state.