Content Of Blood Plasma Research Articles

Measurement of nitrobenzylthioinosine in plasma and erythrocytes: a pharmacokinetic study in mice.

Nitrobenzylthioinosine (NBMPR), a potent inhibitor of nucleoside transport in many cell types, modulates the in vivo disposition of several cytotoxic nucleoside analogs. In this study, a radioligand binding assay was developed for measurement of the NBMPR content of plasma and erythrocytes. The assay was based on the competition between NBMPR and [3H]NBMPR for high-affinity sites on human erythrocytes membranes. With this assay, we followed in mice changes in the NBMPR content of blood plasma and erythrocytes, following the intraperitoneal injection of the disodium salt of NBMPR 5'-monophosphate (NBMPR-P), a prodrug form of NBMPR. The radioligand binding assay was able to measure precisely as little as 2.5 pmol of NBMPR, allowing the direct determination of NBMPR concentrations in plasma as low as 16 nM. As few as 8 x 10(3) molecules of NBMPR per cell could be determined in erythrocytes. The NBMPR content of plasma from mice injected with NBMPR-P was maximal at about 20 min after injection and declined to < 0.2% of the peak value by 10 h. Erythrocyte-associated NBMPR was also maximal at 20 min, and declined to 11% of the peak value by 10 h after injection. Time courses for the disappearance of NBMPR from plasma and erythrocytes were monoexponential and yielded half-life values of 0.39 h and 0.68 h, respectively, an apparent volume of distribution of 0.61 l/kg, and a clearance of 1.1 l/h per kg. The radioligand binding assay is a sensitive and facile method for monitoring NBMPR concentrations in mammalian plasma and tissue extracts.

Glycerineinsatz in broilerrationen mit niedrigem rohproteingehalt1)

Zur Prüfung der Auswirkung eines Glycerineinsatzes in Rationen mit geringem Rohproteingehalt auf Leistungsparameter von Broilerküken erhielten 61 männliche Eintagsküken ad libitum 8 verschiedene Versuchsrationen. Die Rationen basierten auf Mais und Sojaextraktionsschrot und enthielten in einer 3faktoriellen Versuchsanordung 15 oder 18 % CP, waren ohne oder mit Zulage essentieller Aminosäuren bzw. ohne oder mit 10%igem Anteil von reinem Glycerin. Neben der Ermittlung der Lebendmassezunahme und des Futteraufwandes wurde eine N‐Bilanz vorgenommen, die Verwertung von 15N‐Methionin ermittelt sowie die Glycerinaufnahme und ‐ausscheidung bestimmt. Nach 24tägiger Versuchsfütterung wurde der Gehalt an Glycerin im Blutplasma, Leber und Brustmuskel analysiert. Die Zunahmen und die N‐Bilanz waren aufgrund der geringen Rohproteinzufuhr für alle Gruppen sehr gering (BWG 1. bis 23. d: 8,6 bis 17 g/Tier.d; N‐Bilanz 19. ‐23. d: 0,4 bis 1,0 g N/Tierd). Die Zulage von essentiellen Aminosäuren wirkte sich unter den getesteten Einflußfaktoren am deutlichsten leistungssteigemd auf Zunahme, Futteraufwand und N‐Bilanz aus. Die Glycerinausscheidung über die Exkremente betrug bei allen Gruppen mit Glycerinzulage ca. 26 % der Glycerinaufnahme. Der Einsatz von Glycerin erhöhte zwar insbesondere zu Versuchsbeginn die Futteraufnahme, hatte aber keinen gesicherten Einfluß auf den Futteraufwand, die N‐Bilanz oder die Verwertung von 15N‐Methionin. Eine vermutete Einsparung glucoplastischer Aminosäuren durch die Zulage von Glycerin konnte daher nicht nachgewiesen werden. Durch die Glycerinfütterung wurden die Gehaltswerte an Glycerin gegenüber dem Basiswert im Blutplasma im Mittel auf das 23fache (von 0,6 auf 13,6 umol/ml) und im Brustmuskel bis auf das Wache (von 0,4 auf 7,5 umol/g) erhöht. Diese Werte lagen jedoch noch unter dem Glyceringehalt in den Lebern von den Tieren, denen kein Glycerin gefüttert wurde (17,1 bis 19,9 umol/g). Durch 10 % Glycerin in der Ration kam es ebenfalls zu einer signifikanten Erhöhung des Glyceringehaltes in der Leber, im Mittel allerdings nur auf 128 % des Ausgangswertes. Im Hinblick auf eine Verwertung des Glycerins als Nebenprodukt der Fettsäurenmethylesterherstellung kann somit festgestellt werden, daß eine Einbeziehung von 10 % reinen Glycerins in Broilerrationen im Austausch gegen Maisstärke sich nicht nachteilig auf die untersuchten Parameter auswirkte.

Effects of vitamins A and E supplementation on vitamins A and E status of blood plasma, liver and tail fat of fat-tailed sheep

Ram lambs of two Iranian fat-tailed genotypes, Shal (4–6 months) and Sanjabi (6–9 months) were used in experiments for 95 days. They were assigned (25 lambs per breed) into five groups for each breed to receive basal diet plus different levels of vitamins A and E supplementation. The vitamin A groups received 50 or 100 IU vitamin A per kg BW and vitamin E groups received 15 or 30 IU vitamin E per kg diet; the fifth group served as control. Blood plasma, liver and tail fat samples were taken at the beginning and at the end of experiments. Retinol and α-tocopherol concentrations of the samples were determined by high performance liquid chromatography. The highest level of vitamin A application increased the retinol of blood plasma ( P < 0.01) and liver ( P < 0.05) of Shal sheep. The application showed negative correlations to retinol content of tail fat in Shal ( P < 0.01) and Sanjabi breeds ( P < 0.05). The vitamin E application increased the α-tocopherol content of blood plasma in Shal ( P < 0.01) and Sanjabi ( P < 0.001) breeds as well as of liver in the Sanjabi breed ( P < 0.01). The increase was also significant for the tail fat of Shal ( P < 0.01) and Sanjabi breeds ( P < 0.05). As the result of the antagonistic effect of vitamin A on vitamin E status, α-tocopherol concentrations decreased in blood plasma ( P < 0.001), liver ( P < 0.01) and tail fat ( P < 0.001) of both breeds as an effect of vitamin A supply. On the other hand vitamin E supplementation moderately decreased the retinol content of blood plasma ( P < 0.05) in the Shal breed, at the highest level of application but the retinol content of liver tissue increased in the Shal breed ( P < 0.01). Vitamin E application increased the retinol content of tail fat of the breeds, as compared to initial values ( P < 0.05). It was concluded that Shal showed a higher response to vitamin A supplementation and Sanjabi for vitamin E. Therefore different fat-tailed breeds may demand different vitamins A and E supplementation. Concentration of α-tocopherol in blood plasma was a good indicator of vitamin E status in fat-tailed sheep. The sparing effect of vitamin E on retinol status was found in the liver of Shal breed only, but both genotypes showed that effect in tail fat. Tail fat seems to be an active tissue for storage of α-tocopherol but not for retinol at the dose which was used in this study.

Concentrations of vitamin C in milk of sows and in plasma of piglets

Colostrum or milk samples from 10 sows and blood plasma samples from 68 piglets were taken between 0 and 28 d after farrowing and analyzed for ascorbic acid and dehydroascorbic acid by high-performance liquid chromatography with electro-chemical detector. Ascorbic acid content of colostrum (265.0 μm mL−1) was more than twice that of subsequently produced milk (100.0 μg mL−1) at 7 d of age. Ascorbic acid content of blood plasma of piglets at birth after uptake of colostrum was 13.1 μg mL−1, which slowly declined during the first 28 d of age to 3.2 μg mL−1. The dehydroascorbic acid concentration in the plasma of piglets ranged from 3.0 μg mL−1 to 3.9 μg mL−1from 7 d to 28 d of age. There was a significant positive correlation between piglet plasma ascorbic acid and maternal milk ascorbic acid concentration. Key words: Ascorbic acid, dehydroascorbic acid, colostrum

Effects of methyl mercury at different dose regimes on eggshell formation and some biochemical characteristics of the eggshell gland mucosa of the domestic fowl

Eggshell formation and egg production in domestic fowl were studied following the administration of methyl mercury (two dose regimes: 5 mg daily for 6 consecutive days and 1 mg daily for 50 consecutive days). A daily oral dose of 5 mg of methyl mercury for 6 consecutive days induced significant eggshell thinning and deformation and inhibited egg production. Uptake of 45Ca and synthesis of prostaglandins by a homogenate of eggshell gland mucosa from methyl-mercury-treated birds were significantly reduced, as was the calcium content of blood plasma. A daily oral dose of 1 mg of methyl mercury administered for 50 consecutive days also induced eggshell deformation and thinning and reduced egg production. This dose did not, however, have significant effects on the following: 45Ca uptake and prostaglandin synthesis by a homogenate of the eggshell gland mucosa; 45Ca uptake by a homogenate of duodenal mucosa; the Ca content of the blood plasma, shell gland mucosa or shell gland lumen; the HCO 3 − content of the shell gland lumen or the specific gravity of tibia. Methyl mercury added in vitro to a homogenate of eggshell gland mucosa significantly stimulated the synthesis of prostaglandins PGF 2α and PGE 2. Addition of mercury chloride to the same type of preparation stimulated the synthesis of PGF 2α at the expense of thromboxane (T × B 2) synthesis. Administration of 5 mg methyl mercury for 6 consecutive days seemed to reduce the availability of calcium for eggshell formation. This effect could have been due to a direct inhibitory effect of methyl mercury on calcium uptake from the gastrointestinal tract and/or to mobilization of medullary bone. The administration of 1 mg methyl mercury for 50 consecutive days probably induced the reproductive effects by another mechanism. The effects of methyl mercury on avian eggshell formation are quite different from the effects p, p′-DDE exerts on that process.

Effects of Palm Oil Diet on 4, 7, 10, 13,16-Docosapentaenoic Acid Content of Blood Plasma, Red Cells, and Liver and Muscle Lipids in Rats

The effects of palm oil diets on tissue lipids of rats were studied. Four groups of male Sprague-Dawley rats (4wk old) were maintained on diets containing (10% by weight) physically refined palm oil (PRPO), chemically refined palm oil (CRPO), soybean oil (SO), or canola oil (CO) for two months. Both PRPO and CRPO diets resulted in the appearance of 4, 7, 10, 13,16-docosapentaenoic acid (22:5n-6) in blood plasma, red cells, and liver and muscle lipids, while SO and CO diets did not. This fatty acid was principally found in the phospholipid fraction, such as phosphatidylcholine and phosphatidylethanolamine. The increase of 22:5(n-6) compensated for the decrease of docosahexaenoic acid (DHA; 22:6n-3). The results suggest that diet containing only palm oil as a fat source has a high potential of causing α-linolenic acid deficiency in rats.

Effect of riboflavin-binding protein deficiency on riboflavin metabolism in the laying hen

Normal chicken eggs contain substantial amounts of riboflavin, all of which is bound to a specific, high-affinity, riboflavin-binding protein (RfBP). Two hens, genetically unable to produce RfBP and thus unable to deposit sufficient riboflavin in their eggs, were compared to two normal hens with respect to the biological half-life of [ 14C]riboflavin, the tissue distribution of 14C-labeled flavins, and the relative contributions of tissue and dietary riboflavin to flavins deposited in the egg. The biological half-life of [ 14C]riboflavin was slightly but insignificantly less in the RfBP-deficient hens (11.5 ± 1.7 days vs 15.1 ± 3.3 days). The 14C-labeled flavin content of a variety of tissues 3 weeks after the intraperitoneal injection of 5 μCi of riboflavin was also very similar among the four hens. In contrast, the 14C-labeled flavin content of egg yolk, egg albumen, and blood plasma from RfBP-deficient birds was <10% of normal. For all hens, the specific radioactivity of flavins in yolk and albumen was similar to that in liver but less than that in heart. We conclude that riboflavin deposited in egg had equilibrated with the large hepatic flavin pool and was not derived preferentially from unlabeled dietary riboflavin. Other than the inability to deposit riboflavin in their eggs, hens of the mutant strain have normal riboflavin metabolism.

The assessment of episodic metal pollution. II. The effects of cadmium and copper enriched diets on tissue contaminant analysis in rainbow trout (Oncorhynchus mykiss).

Rainbow trout, Oncorhynchus mykiss, were fed on a commercial feed enriched with either Cd or Cu for 32 days and allowed to recover on normal food for 12 days. The body burden of fish fed Cd-enriched diet increased from about 0.05 to 0.39 micrograms/g wet weight, reflected by elevation in the Cd content of gill, liver, blood plasma, kidney, skin, mucus, and whole gut. Muscle Cd content did not alter. Most organs remained contaminated with Cd after 12 days depuration. The body burden of animals fed Cu-enriched diet increased from about 1.2 to 1.5 micrograms/g wet weight, with the gill, whole gut, blood plasma, skin, and mucus contaminated after 32 days, no changes in the liver and muscle occurred. All organs, except the gill and kidney, returned to control values after 12 days depuration. In exposed animals, 76 and 53% of the Cd or Cu body burden, respectively, were contained in the gut, unlike waterborne exposure. Differences in the body distribution of toxicants after intermittent waterborne and dietary exposure may identify the principal routes of pollutant uptake. Ratios of toxicant concentrations in gill/liver may establish the exposure status of fish, but cannot be used to differentiate dietary and waterborne contamination. Analysis of mucus may identify waterborne Cu exposure; dietary and waterborne contributions to mucus Cd content are more difficult to establish.

Fluid electrolyte and hormonal changes in conditioned and unconditioned men under hypokinesia

It has been suggested that hypokinesia (diminished muscular activity) may induce more changes in fluid electrolyte metabolism and hormonal concentration of blood plasma in conditioned than unconditioned men. Thus, the objective of this investigation was to determine the effect of 7 days of hypokinesis (HK) on fluid-electrolyte excretion and hormonal content of blood in 12 physically healthy men aged 19–23 years. They were divided into two equal groups according to their physical conditioning. For the simulation of the hypokinetic effect the men were kept under a rigorous bed rest regime. During the background period (BGP), that is prior to the exposure to HK, and under HK, the rate of elimination of fluid, sodium and potassium, and the content of blood plasma aldosterone and cortisol was measured. The amount of excretion of fluid and electrolytes increased while blood plasma aldosterone content decreased. In the conditioned men, a greater excretion of fluid and electrolytes and a greater reduction of plasma aldosterone concentration was observed. It was concluded that hypokinesia induced substantial changes in fluid-electrolyte excretion and hormonal content of blood plasma in both conditioned and unconditioned men.

Blood plasma lipoprotein and tissue cholesterol of calves fed soybean oil, corn oil, vegetable shortening or tallow

The objective of this study was to determine cholesterol content of blood plasma, blood plasma lipoproteins and tissues of calves fed fats of differing compositions. Groups of 2-week-old calves were fed one of the following fats in a reconstituted milk formula: soybean oil, corn oil, vegetable shortening or tallow. The diets contained no dry feed or added cholesterol. Blood plasma cholesterol concentrations increased with time for all groups. After 15 weeks, cholesterol concentrations were greater in the blood, liver and fat of the groups fed soybean oil and corn oil than in those of the groups fed vegetable shortening and tallow. Low density lipoprotein was identified as the carrier of the increased amounts of cholesterol noted in the blood.

The zinc and copper content of blood leucocytes and plasma from patients with benign and malignant prostates

Zinc and copper levels in plasma have been measured in 41 patients with benign prostatic hypertrophy and 44 patients with carcinoma of the prostate, 24 of whom were receiving some form of hormonal therapy. The zinc concentrations in the blood leucocytes of some of the patients were also examined. We were unable to detect any differences between the leucocyte zinc levels of the three groups examined. Similarly, plasma zinc levels were not affected by age or disease, whereas the plasma copper levels were significantly higher ( p < 0.01) in the benign and malignant categories (mean = 124 μg/100 ml) when compared to a younger normal population (mean = 84.0 μg/100 ml). Hormonal therapy induced a rapid rise in the plasma copper concentrations and a concomitant marginal fall in zinc levels of the carcinoma patients. The magnitude of these hormone-induced changes were dependent on the type of therapy prescribed to the patient.

Effects of progesterone and oestradiol on endometrial metabolism and embryo survival in the ovariectomized ewe

Our objective was to investigate the lipid content of uterus, blood plasma, and milk at early, mid, and late diestrus. Lactating cows (n = 30) had the estrous cycle and ovulation synchronized by administration of exogenous hormones. Cows were blocked by parity and assigned randomly to receive transcervical uterine flushing and biopsy on d 5 (early diestrus), 10 (mid diestrus) or 15 (late diestrus) of the estrous cycle. Flushing and endometrial biopsy were performed in the uterine horn ipsilateral to the corpus luteum. The recovered flushing was used for analyses of lipid composition by liquid chromatography-tandem mass spectrometry and the biopsy was used for investigation of lipid droplet abundance in endometrial cryosections using a neutral lipid fluorescent dye. In addition, blood and milk samples were collected from all cows on d 5, 10, and 15. All blood samples were used to measure the concentration of progesterone in plasma, and all milk samples were used to determine milk composition. Subsamples of blood plasma and milk were also used to evaluate the composition of fatty acids and oxylipins using the same methodology used for uterine flushing samples. The abundance of lipid droplets in the endometrium increased 1.9-fold from d 5 to 10, and 2-fold from d 10 to 15. Concentration of long-chain fatty acids and oxylipins in uterine flushing were, on average, 2.2 and 2.5 times greater in samples collected on d 15 compared with those collected on d 5 and 10. These differences were not observed in blood and milk, suggesting that accumulation of fatty acids and oxylipins in the uterus is regulated locally. In addition to concentration, the profile of individual fatty acids and oxylipins in uterine lumen changed substantially during diestrus. The main categories with increased abundance at late diestrus were mono- and polyunsaturated fatty acids, and oxylipins derived from arachidonic acid, dihomo-γ-linolenic acid, and docosahexaenoic acid. In conclusion, fatty acids and oxylipins accumulate in the uterine lumen during diestrus and might work as a mechanism to supply these lipids to the developing conceptus at late diestrus, when the onset of elongation occurs and substantial synthesis of biomass and cell signaling by lipid mediators are required.

Studies on methods for the determination of amino acid requirements for metabolic balance based on the oxidation rate of 14C labeled lysine to 14CO2

Male experimental rats (100 gm liveweight) were distributed into 10 groups of 8 animals each and received balanced diets, with the exception of lysine which was added to the diets in graded amounts in such a way that the lysine content of the diets ranged from 2.44 to 5.92 gm/16 gm N. After a feeding period of 7 days the animals received 3H- and 14C lysine injected intraperitoneally, 4 animals of each group were investigated for the total CO2 excretion and 14CO2 excretion during the first 2 hrs after the injection and for the urinary excretion of radioactivity (48 hours). The remaining animals in each group were used for determining the plasma amino acids and for establishing the specific radioactivity of free lysine in the liver and muscles after an 1-hour incorporation period. Total CO2 excretion was not found to be influenced by the lysine contents while the level of excretion of 14C activity through CO2 and that of specific 14C activity of CO2 increased with increasing lysine concentrations. This produced a broken curve pattern, showing an increased release of 14CO2 (under maintenance conditions) if the diet contained 4 gm lysine/16 gm N and more. Investigations for the specific 14C activity of free lysine in the liver, the main site of lysine oxidation, showed that the increase in 14CO2 release was due to an enhanced rate of lysine catabolism and was not brought about by changes in the pool volume or in specific radioactivity. The levels of urinary 14C excretion were not found to be related to the lysine content of the diets, whereas the curve pattern of 3H excretion observed 5 to 8 hrs after injection was similar to that of 14CO2 excretion. The lysine content of blood plasma and the content of free lysine in the liver increased continuously with increasing levels of dietary lysine. The methodological studies made in the present paper showed that in scientific research a determination of amino acid requirements on the basis of CO2 oxidation data may be a very exact and sensitive method. It will also yield values for maintenance requirements.

Die Substitution von Eiweißfuttermitteln durch lysinergänzten proteinreichen Weizen während der Aufzucht und Legeperiode von Hennen

A large-scale trial was carried out under commercial conditions to investigate to which extent the feeding of rations with varying lysine content to young hens would influence the crude nutrient content of the body fractions and might change the pattern of amino acid composition and the activity of GOT in the blood. Four rations were fed each containing 14.2% crude protein, 626-633 EFh units/kg and 0.59%, 0.61%, 0.54% and 0.46% lysine. The crude protein and crude fat content of the total body and of body fractions were in no case found to be related to the feeding regime. The proportion of crude ash in the "remainder of non-utilizable parts", in "bones", "intestinal and abdominal fat", "ovaries" and "small intestine" decreased with the decreasing lysine content of the rations. The concentrations of free lysine, histidine, arginine, and phenylalanine in the deproteinized blood plasma of the young hens were significantly (a = 0.01) lower in the birds of the lysine deficient group than in the hens of the other groups. Positive regressions were calculated for the lysine content or the content of aspartic acid in the ration and the pattern of free amino acids in blood plasma. Positive and negative linear relationships were found to exist between the concentrations of free lysine, and those of histidine, arginine or threonine, and serine. A close correlation existed between the total amount of essential amino acids in blood plasma and the lysine concentrations of the plasma. Increasing lysine supplementation produced a decline in the N content of the whole blood and blood corpuscles but a rise in the N content of blood plasma. The activity of GOT in the blood of young hens was not found to be useful as an indicator of the quality of dietary proteins.

Observations on the Effects of Anxiety and Anger on the Content of Concurrent Dreams

Abstract The effects of affects (anxiety, anger) on the content of concurrently ongoing dreams have been studied in 10 college students. Dreams were defined as mental products in which everything (including thoughts) is expressed by means of visual imagery. Anxiety or anger were generated by posthypnotic suggestions. The Ss professed total amnesia for the posthypnotic suggestions. The presence of suggested anxiety or anger concurred with changes of the galvanic skin resistance, the blood pressure, the heart rate, and the free fatty acid content of blood plasma. Analysis of the reported dream contents suggests that the dream content may be altered through endogenous affects that concur with the process of dreaming. Mild or moderate anxiety or anger without a specific content may promote retrieval of old memory traces and incorporation of these memory traces into the dream content. Intensive anxiety (or rage) may result in dreamwork designed to cope with this intensive emotion. This may interfere with the e...

Dental fluorosis and caries in high‐fluoride districts in Sweden

abstract An investigation of the occurrence of fluorosis and caries was carried out in districts in Sweden with extremely high fluoride (F) concentrations in the drinking water. In areas with ∼ 10 ppm F* severe fluorosis, DEAN'S Index Grade 3 and 4, occurred on all permanent teeth and most of the primary teeth. The fluorosis was related to the F supply during the period of mineralization of the teeth. One case of “delayed” fluorosis was, however, demonstrated. In the area ∼ 5 ppm, 50 % of individuals had fluorosis Grade 2 and 28 % Grade 3 or 4 in the permanent teeth. Fluorosis in the primary dentition was milder, but only 20 % of the individuals were completely free from fluorosis and several cases of Grade 3 and 4 occurred in this area also. Caries frequency in the permanent teeth was higher in the ∼ 10 ppm area in comparison with the ∼ 1 ppm area. The highest DMFS values could be related to fluorosis Grade 3 and 4 in both the ∼ 10 ppm and ∼ 5 ppm areas. For the primary teeth the deft value decreased with increasing water F content and the caries frequency was not related to the degree of fluorosis. Duration of breastfeeding influenced the degree of fluorosis in areas up to ∼ 5 ppm in both the primary and secondary dentitions; in areas with ∼ 10 ppm F only the primary dentition was influenced, while the permanent teeth in these areas showed severe fluorosis even with long duration of breastfeeding. F content of saliva was, like the F content of bone and blood plasma, increased in the ∼ 10 ppm area. F deposition in primary teeth from the ∼ 10 ppm area was of the order four times that in the 1 ppm area. Pre‐ and post‐natal F deposition is discussed with reference to analyses of F content of blood and bone, and the significance of these factors during pregnancy.

Dental fluorosis and caries in high‐fluoride districts in Sweden

abstract An investigation of the occurrence of fluorosis and caries was carried out in districts in Sweden with extremely high fluoride (F) concentrations in the drinking water. In areas with ∼ 10 ppm F* severe fluorosis, DEAN'S Index Grade 3 and 4, occurred on all permanent teeth and most of the primary teeth. The fluorosis was related to the F supply during the period of mineralization of the teeth. One case of “delayed” fluorosis was, however, demonstrated. In the area ∼ 5 ppm, 50 % of individuals had fluorosis Grade 2 and 28 % Grade 3 or 4 in the permanent teeth. Fluorosis in the primary dentition was milder, but only 20 % of the individuals were completely free from fluorosis and several cases of Grade 3 and 4 occurred in this area also. Caries frequency in the permanent teeth was higher in the ∼ 10 ppm area in comparison with the ∼ 1 ppm area. The highest DMFS values could be related to fluorosis Grade 3 and 4 in both the ∼ 10 ppm and ∼ 5 ppm areas. For the primary teeth the deft value decreased with increasing water F content and the caries frequency was not related to the degree of fluorosis. Duration of breastfeeding influenced the degree of fluorosis in areas up to ∼ 5 ppm in both the primary and secondary dentitions; in areas with ∼ 10 ppm F only the primary dentition was influenced, while the permanent teeth in these areas showed severe fluorosis even with long duration of breastfeeding. F content of saliva was, like the F content of bone and blood plasma, increased in the ∼ 10 ppm area. F deposition in primary teeth from the ∼ 10 ppm area was of the order four times that in the 1 ppm area. Pre‐ and post‐natal F deposition is discussed with reference to analyses of F content of blood and bone, and the significance of these factors during pregnancy.

Enzymatic determination of ammonia in blood plasma

A kinetic method is described for the determination of the ammonia content of blood plasma using glutamate dehydrogenase and giving satisfactory accuracy and precision. The reaction mixture is composed of 2.2 ml of 0.05 M diethanolamine buffer pH 8.4, 0.1 ml of 4.2 mM reduced nicotinamide adenine dinucleotide, 0.1 ml of 0.1 M 2-oxoglutarate and 0.5 ml of fresh blood plasma. One tenth ml of glutamate dehydrogenase suspension containing 400 U of the enzyme is added after preincubation for 25 min at 20° and the initial velocity of the enzyme reaction measured by reading or recording the decrease in absorbance at 340 nm due to the oxidation of reduced nicotinamide adenine dinucleotide during glutamate formation from the ammonia present. The ammonia concentration in plasma is obtained from a calibration curve or by calculation. Possible effects of endogenous enzymes are discussed.

Free Amino Acid Ratios in Rumen Fluid, Blood Plasma, Milk, and Feces during Methionine and Methionine Hydroxy Analog Supplementary Feeding

Free amino acid ratios in rumen fluid, blood plasma, milk, and feces of lactating dairy cows were studied following the feeding of four experimental concentrates: A, basal; B. basal plus .11% DL methionine; C. basal plus .11% methionine hydroxy analog (M-analog); and D. basal plus .22% M-analog. Free threonine was increased in rumen fluid by supplementation with the higher M-analog. No significant changes were detected in the proportions of any of the free amino acids of blood plasma. Methionine and lower M-analog supplementation increased aspartic acid and valine in free amino acids of milk.There was a close similarity between proportions of free lysine, glutamic acid, arginine, proline, tyrosine, and phenylalanine in rumen fluid and in milk. The proportions of other free amino acids in rumen fluid and milk were not similar. There was no similarity between proportions of free amino acids in blood with those in rumen fluid or in milk.Experimental concentrates had no effect on the free amino acid content of feces. There was no significant relationship between free fecal amino acids and the free amino acid content of rumen fluid, blood plasma, or milk. Milk yield, body weights, or the digestibility of feed did not change significantly.

Utilization of L-Methionine Sulfoxide by the Rat

Methionine sulfoxide is an expected oxidation product of methionine in foods which undergo lipid oxidation or are treated with strong oxidizing agents like hydrogen peroxide. The extent to which methionine sulfoxide could replace methionine in the diet has therefore been tested using diets which are based upon mixtures of synthetic amino acids. This technique allows the exclusive and controlled testing of methionine sulfoxide, which previous studies using proteins could not achieve. The ability of the young rat to utilize the sulfoxide improves with its age, or alternatively there is a process of adaptation to permit more efficient utilization of the sulfoxide. An unexplained increase in the “methionine-like” content of blood plasma accompanies the ingestion of the sulfoxide.