Absorption isotherms for chloride and rubidium ions have been determined through a wide concentration range for nonvacuolate root tips, and for vacuolate subapical sections of corn root. In the range 0 to 0.5 mm, chloride absorption is hyperbolic with concentration in both tips and proximal sections. At high concentrations, 1 to 50 mm, a second multiple-hyperbolic isotherm for chloride is noted in vacuolate tissue, while the isotherm for nonvacuolate tips rises exponentially. A linear to exponentially rising isotherm is taken to signify diffusive permeation.The same distinction between tip and subapical tissue characterizes Rb absorption. Rb uptake is indifferent to the nature of the counterion at all concentrations in the tip, while the counterion exerts a predictable influence on Rb absorption in proximal tissue. The effect of a poorly absorbable anion on Rb uptake is greater in the high concentration range. Evidence is presented for the metabolic nature of ion transport into nonvacuolate root tips. Verification is offered that ion uptake is mediated by dual mechanisms, and the thesis is developed that the high-affinity (low K(s)) system mediates ion passage through the plasma membrane while the low-affinity (high K(s)) system implements transport through the tonoplast.

Journal Article↗

PubMed1964

A possible intermediate in the reduction of 3'-phosphoryl-5'-adenosinephosphosulfate to sulfite.

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Adenine Nucleotides↗

PubMedDate not supplied

Differences in interleukin 1 (IL-1), IL-6, tumor necrosis factor and IL-1 receptor antagonist production by human monocytes stimulated with muramyl dipeptide (MDP) and its stearoyl derivative, romurtide.

The immunostimulatory reagents muramyl dipeptide (MDP) and its stearoyl derivative romurtide [MDP-Lys(L18)] were assessed for cytokine inducing activity in human monocytes. Both MDP and romurtide stimulated the production of interleukin-1 (IL-1), IL-6, tumor necrosis factor (TNF) and IL-1 receptor antagonist (IL-1Ra). Kinetics study indicated that IL-1, TNF and IL-1Ra were induced after 4 h stimulation but IL-6 was produced at a later phase. Romurtide induced these cytokines for longer period that MDP. Dose-response study indicated that romurtide was far more potent than MDP in induction of IL-1, IL-6 and TNF. Although the magnitude of the IL-1 and IL-6 induction was almost the same, that of TNF induction was greater in romurtide-stimulated monocytes than in MDP-stimulated cells. Among IL-1, IL-1 beta appeared to be a major product. In contrast to other cytokines, IL-1Ra was induced by MDP and romurtide in a similar dose and time dependent manner with similar magnitude of response. These studies indicate that MDP and romurtide, especially romurtide, are very potent inducers of both immunostimulatory and immunosuppressive cytokines by human monocytes but with different efficacy and kinetics.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMedDate not supplied

Appetite and taste preference in growing rats given various levels of protein nutrition.

The cephalic gustatory stimuli during a meal yield nutritional information and aid in the efficient control of homeostasis. This study was focused on either appetite for flavored food or feeding behavior in growing male Sprague-Dawley rats under various states of protein nutrition. In fasted rats, endogenous protein degradation was suppressed by ingestion of glucose that was sufficient to meet energy needs. The decrease in the amount of diet intake was compensated by sugar ingestion, except for sucrose. Rats that ingested sucrose exceeded 115% of total energy intake, compared to ingestion of saccharin as a control. Appetite and meal size are primarily dependent upon the dietary protein level, whether it was beyond normal requirements or not and, thus, flavoring by certain taste material is effective for a diet sufficient in protein, but not for a deficient one. In addition, rats fed a diet containing amino acids preferred saccharin and monosodium L-glutamate (MSG) and grew normally. But, when L-tryptophan-deficient diet was offered, the preference for tryptophan was elicited, and then MSG intake was elevated and their growth became normal. However, preference for saccharin never occurred because the level of tryptophan in blood fluctuated and was not maintained within normal limits. The strong preference for sweetness that is evoked by starvation is directly regulated by the negative energy balance. The animals' primary concern was energy intake and their second concern was protein nutrition, regardless of flavoring.

Aging↗

PubMedDate not supplied

Release of hypothalamic norepinephrine during MSG intake in rats fed normal and nonprotein diet.

Effects of monosodium L-glutamate (MSG) solution (0.06 M) on interstitial levels of norepinephrine (NE) were measured in the lateral hypothalamus (LH). Wistar male rats, housed in standard operant boxes, were fed either normal or nonprotein diet for 3 days. Beside a daily bar-mediated drinking session (75 min), animals were without access to fluids. Microdialysates, collected from the LH during the 75 min of drinking, were analyzed using high-pressure liquid chromatography. No significant responses of the LH NE to the drinking of distilled water, MSG, NaCl (0.06 M), and glucose solution (0.6 M) were found in normally fed rats. However, a specific decline in LH NE release was detected during MSG solution-drinking in rats fed nonprotein diet. As MSG preference indicates protein intake, it is possible that LH NE is, at least partially, one of the brain signals that relate MSG preference to dietary protein intake.

Animals↗

PubMedDate not supplied

Use of thermal photography to explore the age-dependent effect of monosodium glutamate, NaCl and glucose on brown adipose tissue thermogenesis.

Using a sensitive thermocamera and a hairless substrain of Sprague-Dawley rats, we developed a novel in vivo method for the evaluation of diet-induced thermogenesis. The technique enabled time-dependent monitoring of spatial heat dissipation emanating from brown adipose tissue (BAT) during diet intake. Drinking of monosodium glutamate (MSG) solution (0.12 M) enhanced standard protein (15%) diet-induced heat dissipation in young (9-12 weeks old) hairless male rats. No significant enhancement was found in 9- to 12-week-old rats that received sodium chloride (0.12 M) or glucose solution (0.6 M). The enhancing effect of MSG was age-dependent and it was not observed in 18- to 22-week-old rats due to an age-dependent decrease of thermogenic responses. No age-related changes in MSG preference or diet intake were recorded. Although it is unclear whether the effect of MSG was purely enhancing or whether the effect was independently superimposed on the diet-induced thermic activity, the results suggest that in 9- to 12-week-old rats, preference for umami taste might be associated with its enhancing effect on diet-induced thermogenesis.

Adipose Tissue, Brown↗

PubMedDate not supplied

Enhancement of liposome-mediated gene transfer to human airway epithelial cells by replication-deficient adenovirus.

We hypothesized that replication-deficient adenovirus (Ad), when complexed with plasmid DNA (pl) and cationic liposomes (L), would enhance liposome-mediated gene transfer in cultured human airway epithelial cells. Pl/L/Ad complexes were formed using charge-charge interactions. A gel electrophoresis retardation assay showed plasmid DNA to be associated with the virus in a high-molecular-weight, low-mobility complex, the diameter of which was 300 to 350 nm. Compared to pl/L alone, pl/L/Ad enhanced luciferase expression on average by 1 log-fold in human airway epithelial cells which express either mutant or wild-type cystic fibrosis transmembrane conductance regulator (CFTR). Transgene expression was sustained at high levels for up to 7 days following transfection with pl/L/Ad. Using a heat-stable alkaline phosphatase reporter gene, we showed that a larger fraction of cells was transfected by pl/L/Ad compared to pl/L. Finally, cells were exposed to Ad for 0 to 24 hours prior to pl/L or exposed to pl/L prior to Ad. We found that enhancement was significantly greater using pl/L/Ad compared to the simultaneous addition of Ad with the pl/L complexes. In addition, when pl/L was added 4 to 24 hours prior to Ad, some enhancement was found, suggesting that plasmid DNA remained in a compartment in the cell for several hours and became available for transcription with the addition of Ad. When Ad was added prior to pl/L, enhancement was found suggesting that the effect of the virus on cell membranes may persist for up to 24 hours. We conclude that the tripartite pl/L/Ad complex significantly enhances liposome-mediated transgene expression for a prolonged period of time in human bronchial epithelial cells.

Adenoviridae↗