Supplementation with L-Glutamine and L-Alanyl-L-Glutamine Changes Biochemical Parameters and Jejunum Morphophysiology in Type 1 Diabetic Wistar Rats

We evaluated the effects of the supplementation with L-glutamine and glutamine dipeptide (GDP) on biochemical and morphophysiological parameters in streptozotocin-diabetic rats. For this purpose, thirty animals were distributed into six groups treated orally (gavage) during thirty days: non diabetic rats (Control) + saline, diabetic + saline; Control + L-glutamine (248 mg/kg), Diabetic + L-glutamine (248 mg/kg), Control + GDP (400 mg/kg), Diabetic + GDP (400 mg/kg). Diabetes was induced by an intravenous injection of streptozotocin (60 mg/kg) and confirmed by fasting glucose ≥ 200 mg/dL. Physiological parameters, i.e., body mass, food intake, blood glucose, water intake, urine and faeces were evaluated during supplementation. After the period of supplementation, the animals were euthanized. The blood was collected for biochemical assays (fructosamine, transaminases, lipid profile, total protein, urea, ammonia). Moreover, the jejunum was excised and stored for morphophysiological assays (intestinal enzyme activity, intestinal wall morphology, crypt proliferative index, number of serotoninergic cells from the mucosa, and vipergic neurons from the submucosal tunica). The physiological parameters, protein metabolism and intestinal enzyme activity did not change with the supplementation with L-glutamine or GDP. In diabetic animals, transaminases and fructosamine improved with L-glutamine and GDP supplementations, while the lipid profile improved with L-glutamine. Furthermore, both forms of supplementation promoted changes in jejunal tunicas and wall morphometry of control and diabetic groups, but only L-glutamine promoted maintenance of serotoninergic cells and vipergic neurons populations. On the other hand, control animals showed changes that may indicate negative effects of L-glutamine. Thus, the supplementation with L-glutamine was more efficient for maintaining intestinal morphophysiology and the supplementation with GDP was more efficient to the organism as a whole. Thus, we can conclude that local differences in absorption and metabolism could explain the differences between the supplementation with L-glutamine or GDP.     

De novo pyrimidine biosynthesis in isolated rat hepatocytes. Quantitative aspects of the regulation by UTP

Quantitative aspects of de novo pyrimidine biosynthesis in rat hepatocytes were monitored. A reduction of intracellular UTP contents by different concentrations of D-galactosamine led to a dose-dependent increase of 14CO2 incorporation into the sum of all acid-soluble uracil nucleotides. In controls the rate of de novo synthesis which was calculated from the incorporation rate of 14CO2 into the sum of all acid-soluble uracil nucleotides was 0.014 mumol X h-1 X g-1 compared to 0.056 mumol X h-1 X g-1 wet weight of liver in situations of a maximally stimulated de novo synthesis. Incubation of hepatocytes with uridine led to a dose-dependent reduction of 14CO2 incorporation to less than 25% of the amount incorporated in the controls. Alterations of the CTP content had no influence on the 14CO2 incorporation. In the presence of high D-galactosamine concentrations the increase of the total amount of acid-soluble uracil nucleotides exceeded the rate of the de novo synthesis derived from the incorporation of 14CO2 into the sum of the acid-soluble uracil nucleotide pool. It was also greater than the increase of the total amount of intra- and extracellular orotate after acidic hydrolysis--even in the presence of 6-azauridine, which stimulated de novo pyrimidine biosynthesis by itself.     

Carbon input by roots into the soil: Quantification of rhizodeposition from root to ecosystem scale

Despite its fundamental role for carbon (C) and nutrient cycling, rhizodeposition remains ‘the hidden half of the hidden half’: it is highly dynamic and rhizodeposits are rapidly incorporated into microorganisms, soil organic matter, and decomposed to CO₂. Therefore, rhizodeposition is rarely quantified and remains the most uncertain part of the soil C cycle and of C fluxes in terrestrial ecosystems. This review synthesizes and generalizes the literature on C inputs by rhizodeposition under crops and grasslands (281 data sets). The allocation dynamics of assimilated C (after ¹³C‐CO₂ or ¹⁴C‐CO₂ labeling of plants) were quantified within shoots, shoot respiration, roots, net rhizodeposition (i.e., C remaining in soil for longer periods), root‐derived CO₂, and microorganisms. Partitioning of C pools and fluxes were used to extrapolate belowground C inputs via rhizodeposition to ecosystem level. Allocation from shoots to roots reaches a maximum within the first day after C assimilation. Annual crops retained more C (45% of assimilated ¹³C or ¹⁴C) in shoots than grasses (34%), mainly perennials, and allocated 1.5 times less C belowground. For crops, belowground C allocation was maximal during the first 1–2 months of growth and decreased very fast thereafter. For grasses, it peaked after 2–4 months and remained very high within the second year causing much longer allocation periods. Despite higher belowground C allocation by grasses (33%) than crops (21%), its distribution between various belowground pools remains very similar. Hence, the total C allocated belowground depends on the plant species, but its further fate is species independent. This review demonstrates that C partitioning can be used in various approaches, e.g., root sampling, CO₂ flux measurements, to assess rhizodeposits’ pools and fluxes at pot, plot, field and ecosystem scale and so, to close the most uncertain gap of the terrestrial C cycle.     

Diet acceptance and preference of the edible grasshopper <Emphasis Type="Italic">Ruspolia differens</Emphasis> (Orthoptera: Tettigoniidae)

The edible grasshopper Ruspolia differens (Orthoptera: Tettigoniidae) gathered seasonally from the wild is a highly valued and an economically important edible insect, particularly in East Africa. To reduce the pressure on wild populations, a sustainable mass production technique needs to be developed. Unfortunately, however, basic biological know-how on feeding habits of R. differens is poorly understood, which poses a constraint on the development of mass-rearing technology. Here, we evaluated the acceptance and feeding preference of R. differens for 16 cultivated or processed foods using no-choice and multiple-choice laboratory bioassays. The results indicated that adult R. differens can eat a wide variety of foods but does not necessarily accept all the foods equally. Furthermore, our experiments showed that R. differens has high ability to select diet among those available. The order of decreasing preference was wheat bran > germinated finger millet > rice seed head > finger millet seed head > chicken feed egg booster > sorghum seed head. Finally, our study indicated that sex and color morph are not associated with the order of acceptance and preference of diets in R. differens. These results show potential foods that could be utilized for developing future mass-rearing methods for R. differens.     

Von Hippel-Lindau (VHL) disease with pheochromocytoma in the Black Forest region of Germany: evidence for a founder effect

We identified a germline missense mutation at nucleotide 505 (T to C) of the VHL tumor suppressor gene in 14, apparently unrelated, VHL type 2A families from the Black Forest region of Germany. This mutation was previously identified in two VHL 2A families living in Pennsylvania (USA). All affected individuals in the 16 families shared the same VHL haplotype indicating a founder effect. This missense mutation at codon 169 (Tyr to His) would probably cause an alteration in the structure of the putative VHL protein. The association of this distinct mutation with the pheochromocytoma phenotype in VHL may help to elucidate the genetic mechanism of carcinogenesis in this multi tumor cancer syndrome.     

Calcium regulation of skeletal myogenesis: IV A defined culture medium permissive for myotube formation and the use of the calcium antagonist lanthanum

Summary Lanthanum has been used effectively in studies of calcium physiology in experiments of short duration. In experiments of longer duration, we report that solutions, such as cell culture medium, containing lanthanum (La⁺⁺) undergo a decrease in pH on the time scale of hours. Presumaly, the decrease in pH is a consequece of the hydrolysis of water by the solution-active La⁺⁺⁺ ions. We have devised a defined culture medium without serum and chick embryo extract which is permissive for myotube formation. This defined medium is also useful for studies of La⁺⁺⁺ as a calcium antagonist. with Ca⁺⁺ to low-Ca⁺⁺ fusion-blocked cultures. This study was supported in part by NIH grants NS 10196 and AM 25202 and The Muscular Dystrophy Association.     

Characterization of the binding of 3H-SCH 23390, a selective D-1 receptor antagonist ligand,in rat striatum

A novel benzazepine, SCH 23390, has recently been described as a very potent and selective dopamine D-1 receptor antagonist based on its potent inhibition of dopamine sensitive adenylate cyclase and its selective displacement of ³H-piflutixol from rat striatal receptor sites. In the present study, the in vitro binding of ³H-SCH 23390 to specific striatal receptor sites has been characterized. Binding was saturable and stereospecific, and the results of both saturation and competition studies are consistent with the binding of ³H-SCH 23390 to a single striatal site. A K_D of 0.53 nM was obtained through Scatchard analysis. Relative potencies of a variety of neuroleptics in competing with ³H-SCH 23390 nd also ³H-spiperone support an interpretation that the single site to which ³H-SCH 23390 binds is the D-1 dopamine receptor. Also, the binding capacity of ³H-SCH 23390 (69 pmoles/gm wet weight) is in agreement with published values for the binding capacities of ³H-piflutixol and ³H-flupentixol. These data, coupled with the low level of non-specific binding encountered with this radioligand (4–8% of total binding at normally employed ligand concentration of 0.3 nM), its high specific activity and its negligible binding to plastic and glass surfaces make it ideally suited for studying interactions with this receptor.