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PubMed1994

Concentrations of urinary metabolites in workers exposed to monochlorobenzene and variation in the concentration during a workshift.

Urinary concentrations of metabolites of monochlorobenzene were examined in 10 male workers exposed to the compound while synthesising intermediate products for dyes. Their individual exposure concentrations were monitored for the whole workshift and samples of urine were collected at the start and end of the workshift, during it, and during the noon recess. The concentrations of four metabolites, 4-chlorocatechol and o-, m-, and p-chlorophenol, in the urine samples were measured. The investigation was performed on Monday and Tuesday in one week and on Tuesday and Wednesday in another week. The concentrations of 4-chlorocatechol in urine collected during the last four hours and at the end of the workshift were proportional to the eight hour time weighted average exposure to monochlorobenzene. The concentration in urine collected during the noon recess showed a linear correlation with the four hour time weighted average in the morning. Similarly, linear relations were obtained for urinary p-chlorophenol. The ratio (as monochlorobenzene) of p-chlorophenol to 4-chlorocatechol concentrations at the start of the workshift was 0.39 and at the end of the workshift was 0.22. The ratios of the urinary concentrations 15 hours after exposure to those at the end of exposure were 0.24 for 4-chlorocatechol and 0.44 for p-chlorophenol. The present study also showed that variations in exposure at the workplace were reflected by changes in concentrations of urinary metabolites during the workshift.

Adult↗

PubMed2002

Smoking a single cigarette rapidly reduces combined concentrations of nitrate and nitrite and concentrations of antioxidants in plasma.

BACKGROUND: Cigarette smoking is a well-known risk factor for the development of cardiovascular disease, yet the mechanism of action involved is not completely understood. Because cigarette smoke contains superoxide and other reactive oxygen species, it has been hypothesized that some of the adverse effects of smoking may result from oxidative damage to endothelial cells, which results in nitric oxide (NO) shortage. However, little information is available regarding the acute effects of smoking on plasma concentrations of NO and antioxidants. We measured the changes in the combined plasma concentrations of nitrate and nitrite as an index of NO concentration, as well as changes in concentrations of major serum antioxidants (ascorbic acid, cysteine, methionine, and uric acid) in smokers after smoking a single cigarette. METHODS AND RESULTS: A randomized crossover study of the effects of smoking a single cigarette was performed in 20 smokers. Smoking a sham cigarette induced no significant changes in all assayed parameters. However, smoking a single cigarette significantly decreased nitrate and nitrite plasma concentrations by 3.5 +/-1.2 and 3.4 +/- 1.1 micromol/L, compared with plasma concentrations at presmoking and sham smoking, respectively. The concentrations of ascorbic acid and other antioxidants were also significantly lower after smoking a single cigarette. These parameters returned to preexperimental levels 60 minutes after smoking cessation. CONCLUSION: The present findings indicate that smoking a single cigarette temporarily decreases nitrate, nitrite, and serum antioxidant concentrations in the plasma. These transient changes may partially contribute to coronary vasoconstriction, which is routinely observed after smoking.

Adult↗

PubMed1981

Influence of the vitamin D-binding protein on the serum concentration of 1,25-dihydroxyvitamin D3. Significance of the free 1,25-dihydroxyvitamin D3 concentration.

The influence of the serum binding protein (DBP) for vitamin D and its metabolites on the concentration of its main ligands, 25-hydroxyvitamin D(3) (25-OHD(3)) and 1,25-dihydroxyvitamin D(3) (1,25-[OH](2)D(3)) was studied. The concentration of both 1,25-(OH)(2)D(3) and DBP in normal female subjects (45+/-14 ng/liter and 333+/-58 mg/liter, mean+/-SD, respectively; n = 58) increased during the intake of estro-progestogens (69+/-27 ng/liter and 488+/-90 mg/liter, respectively; n = 29), whereas the 25-OHD(3) concentration remained unchanged. A positive correlation was found between the concentrations of 1,25-(OH)(2)D(3) and DBP in these women. At the end of pregnancy, the total concentrations of 1,25-(OH)(2)D(3) (97+/-26 ng/liter, n = 40) and DBP (616+/-84 mg/liter) are both significantly higher than in nonpregnant females and paired cord serum samples (48+/-11 ng/liter and 266+/-41 mg/liter, respectively). A marked seasonal variation of 25-OHD(3) was observed in pregnant females and their infants, whereas in the same samples the concentrations of both DBP and 1,25-(OH)(2)D(3) remained constant throughout the year. The free 1,25-(OH)(2)D(3) index, calculated as the molar ratio of this steroid and DBP, remains normal in women taking estro-progestogens, however, and this might explain their normal intestinal calcium absorption despite a high total 1,25-(OH)(2)D(3) concentration. In pregnancy the free 1,25-(OH)(2)D(3) index remains normal up to 35 wk of gestation, but during the last weeks of gestation, the free 1,25-(OH)(2)D(3) index increases in both circulations. A highly significant correlation exists between the (total and free) 25-OHD(3) and 1,25-(OH)(2)D(3) concentrations in maternal and cord serum both at 35 and 40 wk of gestation.

Adult↗

PubMed1989

At physiologic albumin/oleate concentrations oleate uptake by isolated hepatocytes, cardiac myocytes, and adipocytes is a saturable function of the unbound oleate concentration. Uptake kinetics are consistent with the conventional theory.

To reexamine the role of albumin in cellular uptake of long chain fatty acids, we measured [3H]oleate uptake by isolated hepatocytes, adipocytes, and cardiac myocytes from incubations containing oleate/albumin complexes at molar ratios from 0.01:1 to 2:1. For each ratio the uptake was studied over a wide range of albumin concentrations. In all three cell types and at any given oleate/albumin ratio, the uptake appeared saturable with increasing concentrations of oleate:albumin complexes despite the fact that the unbound oleate concentration for each molar ratio is essentially constant. However, the "Km" but not the "Vmax" of these pseudosaturation curves was influenced by substrate availability. At low albumin concentrations, uptake velocities did not correlate with unbound oleate concentrations. However, observed and expected uptake velocities coincided at albumin concentrations approaching physiologic levels and were a saturable function of the oleate/albumin ratios and the consequent unbound oleate concentrations employed. Hence, under the experimental conditions employed in this study using a variety of suspended cell types, oleate uptake kinetics were consistent with the conventional theory at physiologic concentrations of albumin.

Adipose Tissue↗

PubMed2004

Nifedipine decreases sVCAM-1 concentrations and oxidative stress in systemic sclerosis but does not affect the concentrations of vascular endothelial growth factor or its soluble receptor 1.

Microvascular injury, oxidative stress, and impaired angiogenesis are prominent features of systemic sclerosis (SSc). We compared serum markers of these phenomena at baseline and after treatment with nifedipine in SSc patients. Forty successive SSc patients were compared with 20 matched healthy subjects. All SSc patients stopped taking calcium-channel blockers 72 hours before measurements. Twenty SSc patients were also examined after 14 days of treatment with nifedipine (60 mg/day). Quantitative ELISA was used to measure the serum concentrations of vascular endothelial growth factor (VEGF), soluble VEGF receptor 1 (sVEGFR-1), soluble vascular cell adhesion molecule 1 (sVCAM-1), carbonyl residues, and advanced oxidation protein products (AOPP). The median concentrations of VEGF, sVEGFR-1, sVCAM-1, carbonyl residues, and AOPP were significantly higher in SSc patients than in healthy subjects at baseline. A correlation was found between VEGF concentration and carbonyl residue concentration (r = 0.43; P = 0.007). Nifedipine treatment led to a significant decrease in concentrations of sVCAM-1, carbonyl residues, and AOPP but did not affect concentrations of VEGF and sVEGFR-1. Nifedipine treatment ameliorated endothelium injury in patients with SSc, as shown by the concentrations of adhesion molecules and oxidative damage markers. The fact that VEGF and sVEGFR-1 concentrations were not changed whereas oxidative stress was ameliorated by nifedipine is consistent with the hypothesis that VEGF signalling is impaired in SSc. However, more experimental evidence is needed to determine whether the VEGF pathway is intrinsically defective in SSc.

Biomarkers↗

PubMed1978

17 beta-Estradiol and progesterone concentrations in myometrium of pregnancy and their relationships to concentrations in peripheral plasma.

17 beta-Estradiol (E2) and progesterone (P) concentrations in blood and in the myometrium of human pregnancy at term (n=33) and in a few samples (n=5) around midterm of pregnancy were determined. E2 concentration in the myometrium (per g wet wt) at midterm was lower than the concentration in the plasma (per ml) so that the myometrium to plasma (My:Pl) ratio was 0.7. Relative to plasma concentration, the myometrial E2 increased little from midterm to term so that My:Pl was only 0.2 at term. Although P concentration in the myometrium was much greater than that in the plasma at midterm, My:Pl ratio being 2.2, it was lower than that in plasma at term so that My:Pl ratio was only 0.6. A fairly good correlation between plasma steroids and the myometrial steroids was observed at midterm but was distorted at term, probably due to saturation of the tissue-binding capacity. Steroid concentrations determined on the basis of protein showed a good correlation to the values expressed on the basis of wet weight. Whereas myometrial E2 concentration was significantly influenced by the distance from placenta, P concentration was not.

Estradiol↗

PubMed2004

Allele-specific change of concentration and functional gene dose for the prediction of steady-state serum concentrations of amitriptyline and nortriptyline in CYP2C19 and CYP2D6 extensive and intermediate metabolizers.

BACKGROUND: Recently, new polymorphisms were described in connection with intermediate and ultrarapid CYP2D6 metabolism. These may allow a much desired prediction of metabolic activity within the extensive metabolizer group. The functional consequences are still being discussed with few data available for clinical patients. METHODS: We conducted a prospective, blinded two-center study seeking correlations between CYP2C19 (*2,*3, and *4; conventional PCR) and CYP2D6 genotypes (*1 to *10, *35, and *41; real-time and multiplex PCR) and drug concentrations (Emit and HPLC) in 50 Caucasians receiving amitriptyline (AT; 75 mg twice a day). RESULTS: Eighteen CYP2C19 heterozygotes (*1/*2) had higher AT (P = 0.033) and lower nortriptyline (NT; P = 0.059) concentrations than 30 homozygotes (*1/*1). For CYP2D6, we calculated two new indices, i.e., the allele-specific change of concentration on identical background (ASCOC) and a quantitative functional gene dose. The ASCOC describes the change in NT concentration attributable to a mutant allele compared with the wild type. We found significantly higher concentrations for alleles *4 (95.6%; P <0.0001), *10 (63.3%; P <0.001), and *41 (39.8%; P <0.0001) but not for *2 and *35. Assigning of semiquantitative gene doses of 0, 0.5, or 1 to each allele instead of applying the current classification system (predicted phenotypes: 3 intermediate metabolizers, 46 extensive metabolizers, and 1 ultrarapid metabolizer) produced significant NT concentration differences: gene doses of 0.5 (n =3), 1 (n = 14), 1.5 (n = 11), 2 (n = 21) and 3 (n = 1; P <0.00001). CONCLUSIONS: AT and NT concentrations can be predicted within the group of CYP2D6 extensive metabolizers. The ASCOC provides substantial advantages compared with current methods of analysis. CYP2D6 but not CYP2C19 correlates with the sum of both concentrations used to guide AT therapy.

Adult↗

PubMed1989

[Four putative neuropeptides concentrations in the human urogenital tract. Comparison of the neuropeptides concentration between malignant and benign tissues].

In order to evaluate a possible role of several peptides in the human urogenital tract, peptide concentrations in urogenital tissues collected from surgery were measured using specific radioimmunoassay. The specimens were extracted in boiling 0.5M acetic acid, and these extracts were utilized to measure neuropeptide concentrations, i.e., neuropeptide Y(NPY), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP) and peptide 7B2. The highest concentrations of NPY were found in seminal vesicle (145 +/- 42pmol/g) and vas deference (104 +/- 26pmol/g). There was no significant difference in NPY concentration between malignant and non-malignant tissues (prostate and urinary bladder). High concentrations of VIP were also observed in several urogenital tissues (seminal vesicle, vas deference and urethra). VIP concentrations in prostatic cancer and carcinoma of urinary bladder seemed to be reduced, though no significant difference could be found in each corresponding tissue. Pituitary peptide 7B2 was found to be present in the human urogenital tract in relatively low concentrations. A significant difference was observed in CGRP concentration between carcinoma of urinary bladder and adjacent normal vesicular tissues (p less than 0.05). These four peptide immunoreactivities were further characterized by gel permeation or high performance liquid chromatography. Each main immunoreactivity in urogenital extracts seemed to correspond to each synthetic standard or pituitary extracts (in case of 7B2). These results demonstrated that pituitary peptide 7B2 was shown to be present in the human urogenital tract and that the distribution patterns of these peptides might correlate to their pathophysiological role in the urogenital tract. Furthermore, the absence of CGRP immunoreactivity in carcinoma of urinary bladder may be useful for additional diagnostic information.

Adolescent↗

PubMed2000

Breast milk leptin concentrations in initial and terminal milk samples: relationships to maternal and infant plasma leptin concentrations, adiposity, serum glucose, insulin, lipid and lipoprotein levels.

Leptin has recently been shown to be present in human milk and is produced by mammary epithelial cells. We studied leptin concentrations in human milk and its relationships with maternal and infant plasma leptin concentrations, adiposity, serum glucose, insulin, lipid and lipoprotein levels. We also compared the initial and terminal milk leptin concentrations to investigate whether leptin acts as a satiety factor. Venous blood samples were obtained from 18 healthy lactating women aged from 17-42 years and their 3-120 day-old infants. Breast milk samples were collected just before and immediately after suckling, when the infant had self-terminated sucking. Leptin mean values in breast milk were lower than in maternal plasma (p<0.001). Breast milk log leptin concentrations positively correlated with both maternal and infant plasma log leptin concentrations (p<0.001 and p=0.001, respectively) and negatively correlated with maternal serum total cholesterol and low-density lipoprotein cholesterol levels (p<0.001 and p<0.01, respectively), but did not correlate with maternal and infant adiposity, serum glucose and insulin levels, maternal serum HDL-C, triglyceride levels and infants' lipid and lipoprotein concentrations (p>0.05). Using stepwise multiple regression analysis, maternal plasma log leptin and serum HDL-C concentrations were related to breast milk log leptin concentration (R2=0.82; p<0.0001 and p<0.001, respectively). There was no significant difference between initial and terminal milk leptin levels (p>0.05). We concluded that maternal leptin may be transferred to the infant via milk and may exert biological effects; there may be factors other than adiposity affecting breast milk leptin levels, and that leptin might not contribute to the development of satiation at the end of suckling.

Adipose Tissue↗

PubMed2006

The kinetics of nucleated polymerizations at high concentrations: amyloid fibril formation near and above the "supercritical concentration".

The formation of amyloid and other types of protein fibrils is thought to proceed by a nucleated polymerization mechanism. One of the most important features commonly associated with nucleated polymerizations is a strong dependence of the rate on the concentration. However, the dependence of fibril formation rates on concentration can weaken and nearly disappear as the concentration increases. Using numerical solutions to the rate equations for nucleated polymerization and analytical solutions to some limiting cases, we examine this phenomenon and show that it is caused by the concentration approaching and then exceeding the equilibrium constant for dissociation of monomers from species smaller than the nucleus, a quantity we have named the "supercritical concentration". When the concentration exceeds the supercritical concentration, the monomer, not the nucleus, is the highest-energy species on the fibril formation pathway, and the fibril formation reaction behaves initially like an irreversible polymerization. We also derive a relation that can be used in a straightforward method for determining the nucleus size and the supercritical concentration from experimental measurements of fibril formation rates.

Amyloid↗

PubMed1996

Effects of thyroid hormone on erythrocyte carbonic anhydrase-I and zinc concentrations in vivo and in vitro: clinical usefulness of carbonic anhydrase-I and zinc concentrations in erythrocytes.

Red blood cell (RBC) carbonic anhydrase-I isozyme (CAI) and zinc concentrations were measured in patients with various thyroid diseases. Both concentrations were decreased in patients with hyperthyroid Graves' disease, and the RBC CAI concentration significantly (r = 0.95) correlated with the RBC zinc concentration. After treatment, the normalization of RBC CAI and zinc lagged 2 months behind normalization of plasma T4 and T3 levels. Furthermore, the highest correlation coefficients were observed between RBC CAI and zinc levels and plasma thyroid hormone levels measured 8 weeks earlier. These results indicate that both RBC CAI and zinc levels reflect the integrated plasma thyroid hormone levels over the previous few months. Transient thyrotoxicosis due to destructive (subacute or painless) thyroiditis did not cause significant changes in the RBC CAI and zinc concentrations. Therefore, the measurement of RBC CAI and zinc concentrations may be useful in differentiating patients with Graves' disease from those with transient thyrotoxicosis. T3 at a physiological free concentration significantly decreased CAI concentration in erythroleukemic YN-1 cells and burst forming unit-erythroid-derived cells obtained by culturing peripheral blood mononuclear cells. These cells may be useful in vitro models for investigations of thyroid hormone action in human erythroid cells.

Animals↗

PubMed2000

Relationship between the pixel value in digital subtraction angiography and iodine concentration: study in high iodine concentration with original phantom.

Quantitative digital subtraction angiography (DSA) image analysis based on densitometry is widely accepted and used. For the densitometoric DSA image analysis, it is required that there is a linear relationships between the pixel values on DSA images (DSA values) and contrast medium iodine concentration or the thickness of the vessels or the chambers filled with contrast material. We studied on relationship between the DSA value and iodine concentration especially in high iodine concentration. As for the relationship between DSA values and iodine concentration on the DSA images at low concentration, DSA phantom had a good linear relationship. However, the relationship at the high iodine concentration, DSA phantom sometimes lost this linear relationship. Our results suggested that it was necessary to identify relationship between DSA values and iodine concentration in each DSA system, especially in high iodine concentration setting, for densitometoric DSA image analysis.

Angiography↗

PubMed2002

Plasma adiponectin concentration is associated with skeletal muscle insulin receptor tyrosine phosphorylation, and low plasma concentration precedes a decrease in whole-body insulin sensitivity in humans.

Adiponectin, the most abundant adipose-specific protein, has been found to be negatively associated with degree of adiposity and positively associated with insulin sensitivity in Pima Indians and other populations. Moreover, adiponectin administration to rodents has been shown to increase insulin-induced tyrosine phosphorylation of the insulin receptor (IR) and also increase whole-body insulin sensitivity. To further characterize the relationship between plasma adiponectin concentration and insulin sensitivity in humans, we examined 1) the cross-sectional association between plasma adiponectin concentration and skeletal muscle IR tyrosine phosphorylation and 2) the prospective effect of plasma adiponectin concentration at baseline on change in insulin sensitivity. Fasting plasma adiponectin concentration, body composition (hydrodensitometry or dual energy X-ray absorptiometry), insulin sensitivity (insulin-stimulated glucose disposal, hyperinsulinemic clamp), and glucose tolerance (75-g oral glucose tolerance test) were measured in 55 Pima Indians (47 men and 8 women, aged 31 +/- 8 years, body fat 29 +/- 8% [mean +/- SD]; 50 with normal glucose tolerance, 3 with impaired glucose tolerance, and 2 with diabetes). Group 1 (19 subjects) underwent skeletal muscle biopsies for the measurement of basal and insulin-stimulated tyrosine phosphorylation of the IR (stimulated by 100 nmol/l insulin). The fold increase after insulin stimulation was calculated as the ratio between maximal and basal phosphorylation. Group 2 (38 subjects) had follow-up measurements of insulin-stimulated glucose disposal. Cross-sectionally, plasma adiponectin concentration was positively associated with insulin-stimulated glucose disposal (r = 0.58, P < 0.0001) and negatively associated with percent body fat (r = -0.62, P < 0.0001) in the whole group. In group 1 plasma adiponectin was negatively associated with the basal (r = -0.65, P = 0.003) and positively associated with the fold increase in IR tyrosine phosphorylation (r = 0.69, P = 0.001) before and after the adjustment for percent body fat (r = -0.58, P = 0.01 and r = 0.54, P = 0.02, respectively). Longitudinally, after adjustment for age, sex, and percent body fat, low plasma adiponectin concentration at baseline was associated with a decrease in insulin sensitivity (P = 0.04). In conclusion, our cross-sectional data suggest a role of physiological concentration of fasting plasma adiponectin in the regulation of skeletal muscle IR tyrosine phosphorylation. Prospectively, low plasma adiponectin concentration at baseline precedes a decrease in insulin sensitivity. Our data indicate that adiponectin plays an important role in regulation of insulin sensitivity in humans.

Adiponectin↗

PubMed2002

Effects of an abrupt increase of starch-rich concentrates in the diet of dairy cows on concentrations of volatile fatty acids in the rumen and large intestine and on myoelectric activity of the spiral colon.

OBJECTIVES: To describe the effects of an abrupt increase of concentrates in the diet of dairy cows on myoelectric activity of the spiral colon and on fermentation patterns in the rumen and large intestine. ANIMALS: 6 healthy lactating Simmental x Red-Holstein cows. PROCEDURES: The diet of 6 cows implanted with bipolar electrodes in the spiral colon was changed from hay only to a ration of 50% hay:50% starch-rich concentrates during a period of 60 hours. Myoelectric activity of the spiral colon, concentrations of absolute and undissociated volatile fatty acids (VFA), and pH of ruminal and large intestinal contents were monitored before, during, and after the dietary change. RESULTS: Significant changes in patterns of myoelectric activity of the spiral colon were restricted to phases III and IV of the bovine migrating myoelectric complex and to propagation velocity. Significant alterations were not observed in pH or VFA concentrations in ruminal fluid, but pH decreased and VFA concentrations increased significantly in fecal specimens after the change of diet. CONCLUSIONS AND CLINICAL RELEVANCE: Although rumen fluid is of limited value for measurement of certain indicators of fermentation, fecal samples can be used for measurement of pH and VFA concentrations, which serve as indicators of fermentation patterns in the large intestine. Increased concentrations of VFA and low pH in large intestinal digesta have a minimal influence on myoelectric activity of the spiral colon. Increased luminal VFA concentrations are unlikely to play an important role in the etiopathogenesis of motility disorders of the large intestine in cattle.

Animal Feed↗

PubMed2003

Evaluation of white blood cell concentration, plasma fibrinogen concentration, and an agar gel immunodiffusion test for early identification of foals with Rhodococcus equi pneumonia.

OBJECTIVE: To evaluate WBC concentration, plasma fibrinogen concentration, and an agar gel immunodiffusion (AGID) test for early identification of Rhodococcus equi-infected foals. DESIGN: Prospective study. ANIMALS: 162 foals from a farm with enzootic R equi infection. PROCEDURE: Blood samples were obtained from each foal at 4-week intervals for measurement of WBC and plasma fibrinogen concentrations and at 2-week intervals for detection of anti-R equi antibody by an AGID assay. Diagnostic performance of WBC and fibrinogen concentrations was assessed by use of receiver operating characteristic curve analysis. For each assay, sensitivity, specificity, and predictive values were calculated at various cutoff points; bacteriologic culture of R equi from a tracheobronchial aspirate was used as the reference standard test. RESULTS: Diagnostic performance of WBC concentration was significantly higher than that of fibrinogen concentration. Sensitivity and specificity of measurement of WBC concentration at a cutoff of 13,000 cells/microL were 95.2 and 61.2%, respectively; at a cutoff of 15,000 cells/microL, sensitivity was 78.6% and specificity was 90.8%. When a positive test result was used as the cutoff, sensitivity of the AGID assay was 62.5% and specificity was 53.8%. CONCLUSION AND CLINICAL RELEVANCE: Monitoring WBC concentration is a useful approach for early detection of infected foals on farms with a high prevalence of R equi pneumonia. In contrast, serologic surveillance by use of an AGID assay is of little benefit for that purpose.

Actinomycetales Infections↗

PubMed1998

Effect of dietary energy and protein concentration on the concentration of milk urea nitrogen in dairy ewes.

To study the effects of dietary crude protein (CP) and energy on milk urea N concentrations in dairy sheep, eight pelleted total mixed rations were prepared to obtain two levels of energy density (1.65 and 1.55 Mcal of net energy for lactation per kilogram of dry matter for high energy and low energy rations, respectively) and four concentrations of CP within each energy level (mean CP concentrations, 14.0, 16.4, 18.7, and 21.2% of dry matter). The experimental design consisted of two 4 x 4 Latin squares (one per energy level) with two replications per treatment within each 3-wk period. Milk urea N concentrations were similar between dietary energy levels. Within each energy level, milk urea N was linearly and positively associated with dietary CP content and intake (range of milk urea N concentrations, 12.2 to 25.8 mg/dl for ewes fed high energy rations and 12.9 to 26.7 mg/dl for ewes fed low energy rations). The comparison of these results with those from other trials suggested that milk and blood urea N concentrations are closely correlated with dietary CP concentrations and less closely correlated with dietary CP intake. Our results suggest that milk or blood urea N concentrations can be used as indicators of protein metabolism and intake of lactating ewes.

Animals↗

PubMed1995

Effects of spinach leaf protein concentrate on the serum cholesterol and amino acid concentrations in rats fed a cholesterol-free diet.

The effects of spinach leaf protein concentrate (SPPC) on serum and liver lipid concentrations and on serum free amino acid concentrations were examined in rats fed a cholesterol-free diet containing 2 and 10% fats. The serum total cholesterol, triacylglycerol and phospholipid concentrations in the rats fed an SPPC diet containing 2% corn oil were significantly lower than those of the rats fed a corresponding casein diet. When 10% corn oil or lard was used, the serum cholesterol-lowering effect of the SPPC became insignificant, but the serum and liver triacylglycerol concentrations were kept at significantly lower levels. Both the amounts of fecal neutral steroids and bile acids were significantly higher in the rats fed the SPPC than those of the casein-fed rats. The concentrations of serum threonine, serine, glutamine, glycine, cystine, and isoleucine were significantly higher in the rats fed the SPPC diet containing 2% corn oil compared with those of the control rats, but when the dietary fat was raised to 10%, only glycine showed a higher serum concentration. These results indicate that the SPPC has a stronger cholesterol-lowering effect at a lower dietary fat level, 2%, and the activity is partly due to the inhibition of intestinal absorption of cholesterol and bile acid, and partly due to an increase in the concentration of some of the serum amino acids.

Amino Acids↗

PubMed2006

Seminal malondialdehyde concentration but not glutathione peroxidase activity is negatively correlated with seminal concentration and motility.

OBJECTIVES: Reactive oxygen species (ROS) induced lipid peroxidation is associated with sperm function. Malondialdehyde (MDA) concentration and glutathione peroxidase (GPx) activity represent the lipid peroxidation and spermicidal antioxidant, respectively. We aimed to evaluate the relationship of MDA and GPx levels with sperm parameters. PATIENTS AND METHODS: Specimens were divided into two groups: group 1. normospermia (n=20); group 2. oligoasthenospermia (n=31). Seminal MDA concentration was measured by thiobarbituric acid reaction method. Seminal GPx activity was measured by oxidation of reduced nicotinamide-adenine dinucleotide. Seminal MDA levels and GPx activities in both groups were compared. RESULTS: MDA concentrations in both groups were significantly different (1.52 +/- 0.75 vs. 2.25 +/- 0.88 nM, p = 0.0021). GPx activities in both groups were non-significantly different (0.48 +/- 0.11 vs. 0.47 +/- 0.12 U/ml). MDA levels were negatively correlated with the sperm motility (MDA = -0.014 x motility + 2.62, p =0.017) and concentration (MDA = -0.0045 x concentration + 2.23, p = 0.0166). GPx activities were positively but non-significantly correlated with the sperm concentration and sperm motility. CONCLUSIONS: Seminal MDA concentrations are negatively correlated with sperm concentration and motility, which might provide a simple and useful tool in predicting sperm parameters. GPx activity is non-significantly correlated with the seminal quality. Roles of seminal MDA upon spermatogenesis merits further surveys.

Glutathione Peroxidase↗