Excretion Of Nitrogenous Compounds Research Articles

Nitrogen and phosphorus flux in wastewater from three productive stages in a hyperintensive tilapia culture

Abstract In this research, effect of productive stages in nitrogen and phosphorus excretion in wastewater from hyperintensive tilapia (Oreochromis niloticus) culture was evaluated. Fish were cultivated considering three development stages (fingerling of 1.79 g, juvenile of 36.13 g, and adult of 72.96 g). Nitrite, nitrate, ammonium, and phosphorus concentration were determined in order to know the amount of nutrients excreted per productive stage of the fish at a high stocking density. Biometric data were recorded during the experiment with the purpose of determining the growth behavior of fish, as well as the measurement of the aerobic metabolism. Results showed that survival, growth, and health of fish are not affected by hyperdensity of culture; as well, combined catabolism of proteins and lipids was presented as substrates for energy with value for O:N ratio ranging between 20 and 60. In addition, higher concentration in excretion of nitrogen compounds and phosphorus per gram of fish was recorded in wastewater from a hyperintensive culture in fingerlings than in juveniles and adults. These results suggest the use of this wastewater in the early stages of fish growth, aiming to enhance sustainable systems with maximum use of the resources, such as aquaponics systems.

Efficacy of the N-acetylglucosamine in experimental therapy of chronic kidney disease

The efficacy of N-acetylglucosamine in rats with chronic kidney disease is described in this article. The results of the study show that N-acetylglucosamine significantly increased (p<0.05) the excretion of nitrogen compounds (creatinine by 100.4% and urea by 46.6%) and as a result de-creased the level of azotemia. The intensity of free radical oxidation was significantly decreased (p<0.05) (blood conjugated dienes by 32.9%, blood thiobarbituric acid reactive substances – by 14.1%, kidney conjugated dienes – by 40.1% and kidney thiobarbituric acid reactive substances – by 26.3%) and the balance of kidney antioxidant system was restored. N-acetylglucosamine was significantly superior (p<0.05) to comparator quercetin in renal excretory function and nitro-gen metabolism by the most of indicators and was not inferior to the influence on the free radical oxidation and kidney oxidative stress. Thus, N-acetylglucosamine is advisable to further experimental studies at i.m. administration as a chronic kidney disease treatment.

Changes in the biochemical status of common carp juveniles (Cyprinus carpio L.) exposed to ammonium chloride and potassium phosphate

Biogen elements that enter the water in large quantities are one of the main pollutants in the aquatic environment. They lead both to eutrophication of the reservoir and a decrease in the viability of young fish, acting as toxin. The energy enzyme activity (lactate dehydrogenase and succinate dehydrogenase), nitrogen (glutamate dehydrogenase) metabolism, dephosphorylation processes, and immune protection (by alkaline phosphatase activity) under the long-term action of ammonium nitrogen and phosphorus phosphates was studied. The biological object of research were 30–45 day common carp juveniles (Cyprinus carpio L.). According to our results, the peculiarities of the adaptive reactions of young carp to the action of these compounds have been established. We revealed, that under the loading of ammonium nitrogen, the activity of the processes of anaerobic digestion of energy-intensive complex increases directly in the organs of neutralization and excretion of nitrogenous compounds, namely in the gills. In general, the body of the carp due to these actions reduces the total energy consumption for maximum survival in these environmental conditions. We registered, that under the influence of elevated concentrations of phosphorus phosphates, oxidation of biogen elements to the body's energy needs in the presence of oxygen was observed. The processes of immune defense and dephosphorylation, for which LPh is responsible, also the detoxification, the excretion of nitrogenous substances from the body of carp (GDG) occurred differently depending on the chemical nature of the toxin. Thus, under the influence of ammonium nitrogen there was an increase in the activity of LPh in the highest concentrations of the toxin, and the activity of GDG decreased to reduce the production of ammonia, to avoid endogenous intoxication. Through these load of potassium monophosphate, the rise in the activity of immune defense processes and the involvement of ammonia in the cycle of tricarboxylic acids due to reamination to the energy supply of the processes of counteracting the weak but chronic toxic effects of orthophosphate ion. Under the load of ammonium chloride was observed not only the use of “traditional” energy substrates - glycogen and lipids, as well as proteins, which indicates the high toxicity of this compound for the body of young carp. Through the action of orthophosphate ion, the active use of lipids and even the activation of gluconeogenesis at maximum concentrations, as a reaction to weak long-term chemical stress.

Meat fatty acid and purine derivatives in hair lambs in tropical climates

An experiment was conducted to evaluate the effects of feed restriction and sex class on the intake and digestibility of nutrients as well as meat fatty acid profiles in Santa Ines lambs. Thirty lambs with initial body weights of 13 ± 1.49 kg and ages of 60 d were used in a completely randomized study with a 3 × 2 factorial arrangement consisting of three feeding levels (0 or ad libitum, 30%, and 60% feed restriction) and two sex classes (15 intact male and 15 castrated male), comprising five animals in each treatment. The experimental trial lasted 100 d. Increased feed restriction levels resulted in lower intake (P < 0.001) and higher digestibility of nutrients. There were decreases (P < 0.05) in the excretion of nitrogen compounds and purine derivatives when feed restriction increased. The feed restriction decreased (P < 0.05) the concentrations of C18:2n6 and C18:3n3 in the meat but did not affect the C18:2c9t11. The ratio of polyunsaturated fatty acids:monounsaturated fatty acid was higher in the 60% feed restriction. The results suggest that feed restriction improves nutrient utilization efficiency. The feed restriction up to 30% leads to a higher concentration of saturated fatty acids in meats.

Urea synthesis and excretion in Aedes aegypti mosquitoes are regulated by a unique cross-talk mechanism.

Aedes aegypti mosquitoes do not have a typical functional urea cycle for ammonia disposal such as the one present in most terrestrial vertebrates. However, they can synthesize urea by two different pathways, argininolysis and uricolysis. We investigated how formation of urea by these two pathways is regulated in females of A. aegypti. The expression of arginase (AR) and urate oxidase (UO), either separately or simultaneously (ARUO) was silenced by RNAi. The amounts of several nitrogen compounds were quantified in excreta using mass spectrometry. Injection of mosquitoes with either dsRNA-AR or dsRNA-UO significantly decreased the expressions of AR or UO in the fat body (FB) and Malpighian tubules (MT). Surprisingly, the expression level of AR was increased when UO was silenced and vice versa, suggesting a cross-talk regulation between pathways. In agreement with these data, the amount of urea measured 48 h after blood feeding remained unchanged in those mosquitoes injected with dsRNA-AR or dsRNA-UO. However, allantoin significantly increased in the excreta of dsRNA-AR-injected females. The knockdown of ARUO mainly led to a decrease in urea and allantoin excretion, and an increase in arginine excretion. In addition, dsRNA-AR-injected mosquitoes treated with a specific nitric oxide synthase inhibitor showed an increase of UO expression in FB and MT and a significant increase in the excretion of nitrogen compounds. Interestingly, both a temporary delay in the digestion of a blood meal and a significant reduction in the expression of several genes involved in ammonia metabolism were observed in dsRNA-AR, UO or ARUO-injected females. These results reveal that urea synthesis and excretion in A. aegypti are tightly regulated by a unique cross-talk signaling mechanism. This process allows blood-fed mosquitoes to regulate the synthesis and/or excretion of nitrogen waste products, and avoid toxic effects that could result from a lethal concentration of ammonia in their tissues.

Castor bean meal for cattle finishing: 1—Nutritional parameters

This study was carried out to evaluate the effects of replacing soybean meal (SM) with castor bean meal supplemented (CBT) or not (CBNT) with calcium oxide on the intake, total, ruminal and intestinal apparent digestibility of dietary contituents, ruminal pH, and nitrogen ammonia concentration (NH 3-N), ruminal degradation parameters, and on the ruminal microbial protein synthesis based on urinary purine derivatives excretion or purine bases in the abomasum. Were used 5 Bos indicus crossbreed castrated male cattle were used with average initial body weight of 360 ± 30 kg, fistulated in the rumen and the abomasum, in a 5 × 5 Latin square experimental design. The duration of each experimental period was 14 d, with 8 d of adaptation and 6 d of sampling. The 5 treatments consisted of 4 levels of replacement of SM with CBT (0, 33, 67 and 100% on the DM basis) and one treatment with 100% replacement of SM with CBNT. The diet consisted of 35 and 65% of concentrate and corn silage on the DM basis, respectively. It was verified that DM digestibility was reduced ( P < 0.05) by alkaline treatment of the castor bean meal. With the exception to ruminal apparent digestibility of crude protein (RDCP), there was no effect of calcium oxide ( P > 0.05) on the digestibility of other constituents. We observed an increase in RDCP of 24.2% ( P < 0.05) for the CBNT treatment compared to the CBT. The intestinal digestibility of the dietary constituents was not affected by the percentage of SM replaced with CBT. However, alkaline treatment of the CBNT decreased ( P < 0.05) the intestinal apparent digestibility of ether extract. There was no interaction ( P > 0.05) between treatment and time for ruminal pH; however, ruminal pH was influenced ( P < 0.05) by collection time, with a minimum value of 6.23 estimated at 5.8 h after food delivery. However there was an interaction ( P < 0.05) between treatment and collection time for NH 3-N concentration. There were no observed differences ( P > 0.05) in excretion of nitrogenous compounds in the urine among the different castor bean meal treatments. The N-RNA to total microbial N ratio was not affected by the percentage of CBT, presenting an average of 0.138. No differences were detected ( P > 0.05) between the two methods used to estimate the ruminal microbial protein synthesis. We conclude that castor bean meal supplemented with 60 g kg − 1 of calcium oxide can fully replace soybean meal in crossbreed finishing cattle diets.

Variações diárias nas excreções de creatinina e derivados de purinas em novilhos

Objetivou-se estimar as variações nas excreções diárias de creatinina, uréia e derivados de purinas (DP) na urina utilizando coletas durante seis dias consecutivos e avaliar as concentrações de nitrogênio uréico no plasma (NUP) em novilhos. Utilizaram-se quatro animais, machos castrados, de grau de sangue predominantemente Holandês, peso médio de 445 kg, distribuídos em quadrado latino 4 x 4, com os tratamentos definidos em esquema fatorial 2 x 2 (dois níveis de uréia em substituição ao farelo de soja: 0 e 100%; e dois níveis de oferta de concentrado: 0,75 e 1,25% do PV) e a comparação entre dias de avaliação, em esquema de parcelas subdivididas. O volumoso, constituído de silagem de capim-elefante (80%) e silagem de sorgo (20%), foi fornecido à vontade. A síntese de compostos nitrogenados microbianos, estimada a partir da excreção de DP, foi maior quando houve maior oferta de concentrado e menor quando a proteína do farelo de soja foi substituída pela uréia. Não houve efeito da interação níveis de concentrado &lt;FONT FACE=Symbol&gt;´&lt;/FONT&gt; níveis de uréia nem efeito de níveis de uréia sobre a concentração de NUP e a excreção de N-uréico na urina. As excreções urinárias de uréia, alantoína, ácido úrico e a quantidade estimada de proteína microbiana não foram afetadas pelos dias de coleta de urina. Não houve diferença na excreção de creatinina entre os dias de coleta, sendo obtido valor médio de 25,47 mg/kgPV, 117,92 mg/kg0,75 ou 1,04 mmol/kg0,75. A ausência de efeito de número de dias sobre a excreção de creatinina tem grande aplicação prática. Na estimativa da excreção de creatinina e de derivados de purinas, recomendam-se coletas de urina com duração de 24 horas.

Casca de algodão em substituição parcial à silagem de capim-elefante para novilhos. 2. Parâmetros ruminais e séricos, produção microbiana e excreção urinária de compostos nitrogenados

Quatro novilhos holandeses fistulados no rúmen, com peso médio de 259 kg, foram distribuídos em um quadrado latino 4 x 4 para se avaliar o efeito dos níveis de casca de algodão na dieta de novilhos sobre a concentração de nitrogênio uréico no soro (NUS) e de amônia no rúmen, o pH ruminal, a excreção urinária de uréia e derivados de purinas e a produção de proteína microbiana estimada pelo método das bases purinas omasais e da excreção de derivados de purinas na urina. As dietas experimentais continham na base da matéria seca: 0, 10, 20 e 30% de casca de algodão peletizada, em substituição à silagem de capim-elefante, sendo a dieta total constituída de 60% de volumoso. Não houve efeito dos diferentes tratamentos sobre o pH e as concentrações de amônia no rúmen. A concentração de NUS e a excreção de uréia (em mg/kgPV) diminuíram, enquanto a excreção de derivados de purinas na urina e a síntese de proteína microbiana no rúmen aumentaram linearmente com a inclusão da casca de algodão nas dietas. A estimativa da síntese de proteína microbiana não diferiu entre as metodologias das bases purínicas omasais e dos derivados de purina na urina. A casca de algodão mostrou-se um bom volumoso alternativo, podendo ser fornecida até o nível de 30% na MS total na dieta de novilhos de origem leiteira.

Effects of the organophosphorous methyl parathion on the branchial epithelium of a freshwater fish Metynnis roosevelti

Gills are vital structures for fish, since they are the main site for gaseous exchange as well as partially responsible for osmorregulation, acid-basic balance, excretion of nitrogenous compounds and taste. Chemicals in the water may alter the morphology of branchial cells of fish that are, therefore, a useful model for environmental impact and ecotoxicology studies. In order to investigate the effects of an organophosphorous compound, methyl parathion, on the gills of the fish, samples of Metynnis roosevelti were exposed to lethal (7ppm) and sublethal (1ppm) doses of Mentox 600 CE. Through light and scanning electron microscopy, shrinking of the branchial epithelium, followed by detachment and hyperplasia were observed. Externally, the branchial filaments presented the gradual disappearance of microridges. Even in sublethal doses, the organophosphorous reduced the health and fitness of these fish, as consequence of secondary effects derived from changes in the branchial epithelium, impairing oxygenation and ionic balance of the organism.

Enhancement of photosynthesis and growth of an aridland perennial in response to soil nitrogen pulses generated by mule deer

The altitudinal range of the aridland herbaceous perennial Cryptantha flava overlaps with the wintering range of mule deer ( Odocoileous hemionus) in the Colorado Plateau region of the western United States. Deer do not feed on C. flava, but do influence its microhabitat via excretion of nitrogenous compounds. We were interested in determining the importance of Mule deer in redistributing N across the landscape as well as determining if C. flava was capable of exploiting the ephemeral pulse of this redistributed N. Based on pellet group counts, we found that mule deer deposited on average 16 g N m −2 per year to our study site in northeastern Utah, but these deposits were highly variable spatially. The distribution of pellet groups varied from 3 to 49 per 100 m 2, resulting in 6% of individual plants in the population occurring within 20 cm of a pellet group. We applied a one-time treatment of fresh fecal pellets (0.53 g N per pellet group) and experimental urine (6.4 g urea N) to small pre-reproductive plants to examine plant response to N pulses. Within 1 week of application, leaf N concentrations, instantaneous photosynthetic rates, carboxylation efficiencies, and CO 2 saturated photosynthetic rates were significantly higher for plants receiving simulated urine. Increased photosynthetic rates were maintained for at least 3 weeks post treatment. Over the next 2 years, urine-treated plants had higher growth rates, greater overall size, higher flowering rates, and produced more seed per plant than those not receiving artificial urine. We conclude that C. flava is capable of rapid root uptake and incorporation of nitrogen into photosynthetic structures in response to nitrogen pulses. Mule deer activity has direct population level consequences on this species by increasing spatial nutrient heterogeneity, and the growth and reproductive rate of individuals.

The use of the excretion of nitrogen compounds as an indirect index of the adequacy of dietary protein in chickens

AbstractAn experiment was carried out to study the effect of changes in either the quality or the quantity of dietary protein intake on the excretion of nitrogen (N) compounds in the chicken. Thirty-two White Rock male broilers (1 day old) were raised in batteries and fed a commercial starter diet for 9 days. Then they were randomly divided into eight groups each of four birds, of similar body weight (mean live weight: 178 (s.e. 1·9) g), and individually housed in metabolism cages. Following a paired-feeding design based on metabolic body weight (kg M0·75), each group of birds was given, for an experimental period of20 days, each of four levels of protein (60, 120, 180 or 240 g/kg: 5 days each) in two groups of isoenergetic (14·5 kj metabolizable energy per g dry matter) and semisynthetic diets based on soya-bean meal, known to be first limiting in methionine, either unsupplemented (diets S) or supplemented with 2 g/kg DL-methionine (diets SM). Excreta were collected every 3 days for 48 h, frozen and stored at −20°C. The excreta samples were subjected to chemical analysis for uric acid by a rapid high-performance liquid chromatographic method, for urea and ammonia by a colorimetric method, and for total N by the Kjeldahl procedure. In general, the excretion of major N compounds was markedly affected by either the quality or the content of dietary protein. Overall, the excretion of total N, uric acid-N, ammonia-N and urea-N significantly (P &lt; 0·05) decreased with improvement in dietary protein quality and significantly (P &lt; 0·05) increased with increase in protein intake. Regression equations were obtained relating the excretion of uric acid, urea, ammonia and total N on protein supply. For the partition ofN compounds output, the ratios of uric acid-N and ammonia-N to total N significantly (P &lt; 0·05) decreased on improving dietary protein quality and increased or remained unchanged, respectively, with the increase in dietary protein content. The use of the ratio of ammonia-N to total N is recommended as a rapid, easy and accurate indicator of dietary protein adequacy, as an alternative to measures based on total N balance, without the need for separation of urine and faeces.

An anthropometrical and biochemical assessment of nutritional status in eating disordered patients: Is there a problem of interpretation?

Anthropometric and biochemical parameters were used to evaluate nutritional status in eating disordered (ED) patients. Height and weight were used to calculate body mass index (BMI), and body fat content. Skinfold measurements were assessed and used for the calculation of upper arm fat and muscle areas, and degree of mal-nutrition. All eating disorder patients showed signs of starvation in various degrees. Excretion of nitrogenous compounds were high in all groups. BMI proved to be a poor predictor of nutritional status in ED patients. Fat content estimation from skinfold measurements can give disputable results. The relationship between body fat content and menstruation is questioned.

Nitrogen pollution in mariculture: toxicity and excretion of nitrogenous compounds by marine fish

The toxicological and environmental significance of N-containing effluents discharged to seawater from fish farms is difficult to establish. Environmental quality standards for N compounds in seawater are hard to derive in the context of aquaculture because the toxicity of NH3 and NO2- to marine fish is poorly understood. Furthermore, details of aquacultural effluents are not routinely reported. Marine teleosts excrete N via the gills, skin and faeces, but do not have the metabolic capacity to cause breaches in discharge consent conditions. The most likely cause of discharge consent breaches will be poor farming practice. Nitrogen pollution will arise from food wastage, poor N absorption, and N retention. It is estimated that 52–95% of any N added to the culture system as food will ultimately pollute the environment.

The role of the kidney in electrolyte and nitrogen excretion in a large flightless bird, the emu, during different osmotic regimes, including dehydration and nesting

1. In birds the role of the kidney in excretion may be augmented by the cloaca-rectum, where the final modification of excreta may occur. The emu has a limited ability to concentrate urine but the capacity of its cloaca-rectum to absorb water and NaCl is considerable. Clarification of the characteristics of renal regulation of salt and water excretion is therefore required. 2. The functioning of the kidney was studied during dehydration, nesting, NaCl loading, and NaCl depletion. Glomerular filtration rate (GFR), urine flow rate (UFR), and the patterns of excretion of the major electrolytes were examined. GFR was decreased in response to dehydration, salt loading, and nesting, while UFR was lowered only during dehydration and nesting. A diuresis occurred in the NaCl-depleted birds. 3. Although the limited renal concentrating ability was confirmed, the kidney had excellent water and electrolyte reclaiming abilities. In control emus, 94.8% of water, 99.8% of Na, and 98.7% of Cl were reabsorbed. Even during NaCl loading, 99.5% of Na and 97.9% of Cl were reabsorbed by the kidney. 4. The excretion of nitrogenous compounds was similar to that described in other birds, with uric acid/urates being the major excretory product. Also examined was the binding of cations to precipitated uric acid/urates. In the ureteral urine cation trapping was only of minor significance, with K being the cation most involved, but marked modification of urine can occur in the cloacarectum because the ion binding in excreta can be much increased.

Effects of Snail Grazing on Benthic Algal Community Structure in Different Nutrient Environments

The effects of interaction between nutrient availability and grazing intensity on the structure of benthic algai assemblages were investigated in an ephemeral stream. Small (250 ml) enclosures containing substrata releasing either: 1) no nutrient, 2) 0.5 M KH₂ PO₄ or 3) 0.5 M NaNO₃ were exposed for 19 d to one of five densities of the snail Goniobasis ranging from 0 to 160 snails/m². Algal standing crop (total cell density and community biovolume) on coverslips inside each enclosure decreased with increased grazing pressure in control and nitrate-enriched environments, but increased at low grazing pressure in the phosphate-enriched environment. Responses among constituent populations differed for three reasons: 1) stalked and loosely attached diatoms were more susceptible to snail grazing than firmly attached, prostrate algae; 2) some species were stimulated by phosphorus enrichment and/or grazing while others were not; 3) algal species differed in their response to interactions between grazing and nutrient enrichment. Two alternative hypotheses may explain this interaction: 1) grazers stimulate the growth of understory species by removing overlying cells; 2) excretion of nitrogenous compounds by grazers enhances the effects of phosphorus enrichment alone. Although diversity peaked at intermediate grazer densities in unenriched and nitrate-enriched environments, no significant change was found in phosphate-enriched environments, where the community was dominated either by grazer-sensitive populations that increased faster than they were grazed, or by grazer-resistant algae.

The effect of exogenous factors on prececal nutrient and amino acid absorption, ascertained from swine with ileo-rectal anastomoses. 3. The effect of crude fiber-rich coarse meal supplements to a basic ration

In digestion trials using pigs fitted with ileo-rectal anastomoses and parallel intact pigs the influence of wheat straw meal (WSM) or grass meal (GM) supplemented on two different levels to a basal diet was examined with regard to nutrient and amino acid digestibility resp. absorption. Both roughages reduced, obviously because of their high cell wall contents, nearly at equal amounts and partly significantly the precaecal as well as the total digestibility of dry matter, organic matter, carbohydrates (= crude fibre + NFE), crude fibre and hemicelluloses (arabinose, xylose). By the roughage supplementations the crude protein digestibility at the terminal ileum was less reduced than at the end of the total digestive tract, the starch digestibility was hardly influenced and that of ether extract mostly increased. In comparison with precaecal glucose and fructose digestibilities it could be shown that the anthrone method is not suitable for determinations of the precaecal digestibility of water soluble carbohydrates. Beside these compounds other substances in the ileum digesta must evidently be dyed by anthrone too. The crude protein digestibility and the amino acid absorption were precaecally hardly or not reduced by WSM supplementations, therefore it can be concluded that it is possible to dilute the energy concentration in diets (e.g. for sows) by addition of WSM without impairing protein digestion and amino acid absorption. The GM supplementations, however, impaired protein digestibility and amino acid absorption of the whole diet, probably caused by the encrusted, possibly heat damaged protein present in the GM itself. When the roughage supplemented diets were fed, the excretion of nitrogen compounds in the faeces was enlarged due to the more intensive bacterial activity in the hind gut and the additional sorption effects to cell wall substances, so that a too low apparent and also true digestibility is made believe. The applicability of the difference method to the calculation of protein and amino acid digestibilities in roughages is very questionable because of their low contents and the missing additivity. The crude fibre and hemicellulose digestibility values calculated by the difference method demonstrate for the both roughages--in spite of high standard deviations--that the precaecal digestibility of crude fibre is about zero and that of the hard lignified hemicellulose fraction in contrast to the predominantly endospermic hemicelluloses of the basal diet is very low. The faecal crude fibre and hemicellulose digestibilities of WSM--especially on the lower supplementation levels--are markedly worse than those of GM.

メン羊の絶食進行にともなう尿中窒素成分排泄量の経日的変化

メン羊の絶食進行にともなう尿中窒素成分排泄量の経日的変化

Uptake and excretion of amino acids and utilization of glucose by Schistosoma japonicum eggs.

The utilization of amino acids and glucose in the external nutrients and the excretion of nitrogenous compounds by Schistosoma japonicum eggs were investigated with the eggs cultured in a chemically defined medium (MEMSE-J). Of the 15 amino acids in MEMSE-J, arginine and glutamine markedly decreased in concentration during cultivation of S. japonicum eggs. The nitrogenous excretory products of developing eggs were demonstrated to be at least four amino acids (alanine, proline, glutamic acid and ornithine), urea and ammonia. Glucose was consumed at an estimated rate of 32 ng/living egg/day during the period of egg growth and differentiation. When 14C-labelled glucose was included in the culture medium, the radioactivity was incorporated into three amino acids (alanine, proline and glutamic acid), which were excreted by S. Japonicum eggs. The results were discussed with reference to the possible role in stimulating fibrosis in the granuloma of schistosomiasis.

Renal excretion of nitrogenous compounds in vertebrates.

The renal excretion of nitrogenous compounds plays an important role not only in the elimination of nitrogen end-products but also in regulating the acid-base and osmotic balance of body fluids. The major nitrogenous compounds excreted by the vertebrate kidney are ammonia, urea and uric acid. The present review addresses the renal excretion of these compounds and, in addition, the amino acid taurine. The functions of excretion; the mechanisms of excretion including renal metabolism, renal handling (secretion, reabsorption, and filtration), and transepithelial transport processes; and the factors regulating these mechanisms are discussed. Renal nitrogen excretion among the vertebrate classes from fish to mammals is compared.

Influence of Histamine and Cysteamine on Excretion of Nitrogen Compounds in Spleen Isolated from Irradiated Guinea Pig

The excretion of nitrogen from perfused spleen removed from irradiated and nonirradiated guinea pigs was investigated. It was concluded that cysteamine injected immediately before irradiation reduced the excretion of nitrogen from the isolated spleen. The protective effect of histamine given prior to irradiation was less obvious than that of cysteamine, at concentrations of the two substances that were used.