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At least 1,243 records · Page 69Linked to original sources
PubMed2001

99mTc-HEPIDA plasma clearance as a diagnostic tool. Total plasma v. specific hepatic clearance.

BACKGROUND: (99m)Tc-HEPIDA total plasma clearance has been used for assessment of hepatic parenchyma damage. However, the radiopharmaceutical used is being partly cleared from plasma also by the urinary tract. As the share of the latter route in total elimination of the compound is not well known, the aim of the study was to investigate the percentage of (99m)Tc-HEPIDA eliminated by the kidneys and by the liver. MATERIAL AND METHODS: To this aim total plasma clearance of the compound and urinary part were determined by the methods employed here in 117 patients and in 16 healthy volunteers. The pure hepatic clearance was calculated as the difference between total plasma and the urinary clearance of (99m)Tc-HEPIDA. RESULTS: The urinary clearance in patients amounted from 2.6 to 78% of total clearance; in the healthy volunteers the corresponding range was from 8.6 to 28%. Pronounced spread of the urinary clearance (coefficient of variation = 35%) and lack of correlation between the urinary and total clearance make it necessary to take account of urinary elimination in each patient in whom reasonably accurate assessment of hepatic clearance is required. CONCLUSION: Further studies on the diagnostic efficacy of pure hepatic clearance and its change with age in healthy patients appear necessary.

Journal Article↗
PubMed2005

Plasma total homocysteine concentrations in obese and non-obese female patients with type 2 diabetes mellitus; its relations with plasma oxidative stress and nitric oxide levels.

Hyperhomocysteinemia has been identified as independent risk factor for early atherosclerotic vascular disease. The purpose of our study was to investigate the plasma homocystein (Hcy) concentrations and its relationship with lipid peroxidation as thiobarbituric acid reactive substances (TBARS) and nitric oxide (NOx; nitrite plus nitrate) concentrations in age-matched non-obese (n=55) and obese (n=60) female subjects with type 2 diabetes mellitus. Non-obese diabetic patients have significantly higher plasma tHcy and TBARS (p<0.001 and p<0.001), and significantly lower NOx concentrations than the controls (n=25) (p<0.001). The plasma tHcy and TBARS concentrations were higher and nitric oxide concentrations were lower in obese diabetics than in non-obese diabetics (for each comparison; p<0.001). Correlation analysis demonstrated that there was a significant positive correlation between tHcy and TBARS (r=0.452, p<0.01) in diabetics groups. There was no significant correlation between tHcy and plasma NOx, insulin and blood pressure. We thought that Hcy might have a permissive role on the endothelium damage through free radical generating systems and the presence of obesity the free radical induced-damage has been elevated in diabetic patients.

Blood Pressure↗
PubMed1991

Effects of trazodone on plasma cortisol in normal subjects. A study with drug plasma levels.

Trazodone is a novel antidepressant drug with alpha-adrenolytic activity. Since alpha 1-adrenoceptor mechanisms have been shown to stimulate basal cortisol secretion in healthy humans, the neuroendocrine effects of trazodone (75 mg orally) were evaluated in six healthy subjects. The drug plasma levels were also measured. With respect to placebo, trazodone significantly decreased plasma cortisol concentrations (F = 9.173, p less than 0.01). The areas under the curve (AUC) of plasma trazodone concentrations were negatively correlated with the AUC of plasma cortisol levels (r = -0.95, p less than 0.0005). These results confirm that, in humans, alpha 1-adrenergic mechanisms stimulate the basal secretion of cortisol.

Female↗
PubMed1975

The interaction of human plasma glycoaminoglycans with plasma lipoproteins.

Modifications of existing methods have allowed for the isolation and purification of various species of plasma glycosaminoglycans on the basis of their sulfate content and molecular size. All of the preparations precipitated human plasma low density lipoproteins (LDL); maximal precipitation occurred with amounts of glycans corresponding to 50 mug of hexuronate and 12 mg of LDL. The interaction of glycans with pyrene-labeled lipoproteins was also studied, measuring variations of the fluorescence emitted by the monomer (M) and excimer (E) species of the bound pyrene. The ratio IE/IM is proportional to c/eta, where c is the microscopic concentration of the pyrene confined to the hydrocarbon region of the lipoprotein and eta is the microviscosity of that region. To 0.12 mg of pyrene-labeled LDL, very low density lipoproteins (VLDL) or high density lipoproteins (HDL) were added increasing amounts of the various glycan preparations. The sulfate-rich species decreased the IE/IM ratio of LDL and HDL but not that of VLDL. This finding suggests that the glycan caused a change in lipoprotein conformation associated with either an increased volume or increased microscopic viscosity of the hydrocarbon region. The modification of LDL conformation could be prevented by proteolytic treatment of the sulfate-rich species or by addition to the system of suitable amounts of sulfate-poor species or of chrondroitin-4-sulfate, but could not be prevented by increased ionic concentration. These results suggest that the two main species of plasma glycans are important in maintaining adequate rheological properties of plasma lipoproteins.

Chondroitin↗
PubMed1991

Effects of the K+ channel activators, RP 52891, cromakalim and diazoxide, on the plasma insulin level, plasma renin activity and blood pressure in rats.

In normo- or hyperglycemic (i.v. infusion of 50 mg/kg/min glucose over 30 min) pithed rats, diazoxide (1 mg/kg/min i.v. over 20 min) significantly reduced plasma insulin content. By contrast, cromakalim, nicorandil or RP 52891 even at doses 40-fold higher than those producing the same hypotensive effect as diazoxide in intact anesthetized normotensive rats, failed to change insulin plasma levels. Glibenclamide (0.01-0.3 mg/kg i.v.) pretreatment antagonized dose-dependently the hypoinsulinemic activity of diazoxide with an i.v. ED50 value of 49 +/- 1 microgram/kg. In pithed rats, diazoxide increased markedly plasma renin activity. This effect was almost inhibited completely by 20 mg/kg i.v., but not at all by a 1-mg/kg i.v. dose of glibenclamide. In pentobarbital-anesthetized rats, diazoxide (0.5-2 mg/kg/min i.v. over 20 min) produced decreases in mean carotid artery blood pressure which were antagonized dose-dependently by glibenclamide (5-20 mg/kg i.v.). This sulfonylurea (20 mg/kg i.v.) also prevented the hypotensive effects of several i.v. administered K+ channel activators (cromakalim, RP 52891 and nicorandil) but not those of numerous hypotensive agents such as acetylcholine, adenosine, bradykinin, clonidine, histamine, salbutamol, dihydralazine, papaverine, platelet aggregating factor, nitroglycerin, nitroprusside, nitrendipine and diltiazem. Although glibenclamide lowered plasma glucose levels, its blocking activity vis-à-vis the hypotension evoked by cromakalim was not affected when its hypoglycemic effects were reversed with an i.v. injection of glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Deamidation of glutamine by increased plasma gamma-glutamyltransferase is a source of rapid ammonia formation in blood and plasma specimens.

Owing to increased enzymatic hydrolysis of glutamine, additional ammonia is formed in blood and plasma specimens with increased gamma-glutamyltransferase activity (gamma-GT, EC 2.3.2.2.). The close correlation between gamma-GT and glutaminase (EC 3.5.1.2) activities (r = 0.97) in plasma, the inhibition with 6-diazo-5-oxo-L-norleucin or borate plus serine, and the activation with maleate clearly show that gamma-GT itself is the glutamine-deamidating enzyme in plasma. Under pathological conditions, increased gamma-GT activity can increase the rate of ammonia formation in plasma more than 30-fold the mean values of healthy subjects. Increased in vitro formation of ammonia caused by increased gamma-GT activity is an important source of false-positive findings in ammonia determination. Because of the high prevalence of pathological gamma-GT activities in clinical populations, blood specimens for ammonia analysis should be preserved by addition of borate plus serine.

Ammonia↗
PubMed1978

Effect of temperature and plasma on the exchange of apolipoproteins and phospholipids between rat plasma very low and high density lipoproteins.

The effect of temperature and plasma on the exchange of apoprotein C and phospholipids between VLDL and HDL was studied using 125I-labeled and 32P-labeled VLDL. Temperature affected the exchange of apoproteins and phospholipids similarly, and both were enhanced by increasing the temperature of incubation to 20 degrees C and higher. The exchange of apoC was almost complete within 5 minutes of incubation and was not influenced by the addition of plasma to the incubation mixture. The exchange of phospholipids occurred much more slowly and was enhanced 5- to 10-fold in the presence of plasma. These results indicate that the exchange of both phospholipids and apoC is dependent on the temperature of the incubation, but that they exchange independently, at least in part. It is suggested that the exchange of apoC occurs through dissociation of the apoprotein from the lipoprotein surface to the water phase, whereas the exchange of phospholipids is mediated mainly by a carrier molecule present in plasma and absent in lipoproteins.

Animals↗
PubMed1990

Correlation of plasma norepinephrine and plasma atrial natriuretic factor during lower body negative pressure.

Plasma atrial natriuretic factor (ANF) is released in proportion to intra-atrial pressures. Plasma norepinephrine (NE) levels are considered to be an indirect reflection of sympathetic tone. These two mediators were studied during human regulation of intravascular volume in the course of exposure to fluid shifts associated with a model of gravitational stress, lower body negative pressure (LBNP.) Blood was drawn from 10 normal subjects before and after exposure to 2 min of a graduated increase in LBNP to a level of 55 mmHg followed by 5 min at 55 mmHg. Plasma ANF was measured by RIA and catecholamines by HPLC-ECD. NE increased from 358 +/- 44 (S.E.M) pg/ml to 511 +/- 48 pg/ml (p = 0.03.) Although ANF only decreased from 27.3 +/- 2.4 pg/ml to 23.5 +/- 2.9 pg/ml (p = 0.33,) a statistically significant negative correlation was observed (r = -0.70, p = 0.02) between the changes in NE and ANF induced by LBNP. The modelling of physiologic responses to gravitational stress in this experiment revealed a negative correlation between changes in sympathetic tone (as reflected by plasma NE) and ANF levels.

Adult↗
PubMed1978

Familial lecithin:cholesterol acyltransferase deficiency. Further studies on plasma lipoproteins and plasma postheparin lipase activity of a patient with normal renal function.

Plasma lipoproteins and postheparin plasma were investigated in a patient with familial LCAT deficiency with normal renal function and without proteinuria. As revealed by gelfiltration the large molecular weight LDL2 was not present, and myelin structures were not found in LDL1 or LDL2 when she was on her ordinary diet. After 60--65% fat diet for one week the large molecular LDL2 was found, but only in low concentration. We have no explanation for the difference in the lipoprotein abnormalities of this patient and others with this disease. There is no major difference in the fat content in the ordinary diet of the Norwegian patients with familial LCAT deficiency, nor has our patient any clinical signs of malabsorption. Furthermore, there was no difference in lipoprotein lipase or hepatic lipase activity in postheparin plasma between our patient and others with the same disease. However, whereas hepatic lipase activity was within the reference values, lipoprotein lipase activity was rather low in all patients investigated. We suggest that impaired VLDL catabolism in plasma, because of LCAT deficiency and low lipoprotein lipase activity, may partly explain the low HDL concentration consistently found in patients with familial LCAT deficiency.

Aged↗
PubMed1990

[Problems in standardization of the immunochemical detection of plasma proteins. I. International reference standards for plasma proteins. II. Immunochemical relation of measurement signals and values].

When the results of plasmaprotein determination--dependent on the reagents, methods and other factors--are expressed in international units (IU) a better comparison of the results between different labs is possible. By this means and using the corresponding reference values and reference intervals the reliability of the interpretation of laboratory data will increase. The situation regarding the WHO IRP's for plasma proteins (approx. 20 parameters) and the relation from IU to mg in the reagents of the Behringwerke AG are reported. The overlability of WHO IRP's has not allowed yet to achieve an optimal standardization of the immunochemical methods for measurement of plasma proteins. This depends especially on the complexity of the antigen-antibody reaction. The relationship between the measured signal and the hence obtained value will be discussed in details in the second part of this paper. Hereby especially the reciprocal interdependence between physicochemical properties of proteins and the deriving immunochemical behaviour as well as the dependence of the results from the quality of the antibodies-containing reagents are also considered. Possible solutions for a better control system of the plasma protein determination by using the so called master calibrators as internal support for validation will be presented. Furthermore, general immunochemical postulates and rules for optimization of the standardization of plasma protein determination will be proposed and discussed.

Antigen-Antibody Complex↗
PubMed1987

Plasma fat elimination tissue lipoprotein lipase activity and plasma fatty acid composition during sequential treatment with etretinate and isotretinoin.

In an attempt to elucidate the mechanisms underlying retinoid-induced hyperlipidemia, the effects of etretinate (Tigason) and isotretinoin (Roaccutane) on two different plasma fat elimination variables and on the plasma fatty acid composition were studied. Twelve patients with various hyperkeratotic disorders participated in a double-blind cross-over study of etretinate and isotretinoin. Each drug was given for 8 weeks with an 8-week intermission. On five occasions an intravenous fat tolerance test (IVFTT) was performed and the lipoprotein lipase activity (LPLA) in adipose tissue and skeletal muscle was measured. Isotretinoin significantly reduced the fat elimination rate as measured by IVFTT (p less than 0.001) and also decreased the muscle LPLA (p less than 0.05). The etretinate-induced depression of these variables was not statistically significant. The LPLA of adipose tissue and the plasma fatty acid composition were not markedly altered by any of the drugs. The observed changes are probably not sufficient to entirely explain retinoid-induced hyperlipidemia but the results strengthen the opinion that plasma lipid metabolism is more unfavourably affected by isotretinoin than etretinate.

Adipose Tissue↗
PubMed1989

Protein C inhibitor from human plasma: characterization of native and cleaved inhibitor and demonstration of inhibitor complexes with plasma kallikrein.

Protein C inhibitor (PCI) was purified from human plasma using immunoaffinity chromatography and heparin Sepharose chromatography, a method that allowed the purification of active and inactive inhibitor. PCI purified from outdated plasma was inactive and either in complex with plasma kallikrein or proteolytically degraded. Sequence analysis of cleaved PCI and of complexes between PCI and activated protein C or urokinase identified the previously recognized inhibitor cleavage site Arg354-Ser355. Two additional cleavage sites were observed in the modified inhibitor i.e. Arg357-Leu358 and Arg362-Leu363 which probably represent secondary cleavage of the inhibitor. Furthermore the sequence analysis of the inhibitor, whether purified from fresh or outdated plasma, revealed that it was microheterogeneous in the NH2-terminus as a result of cleavage by a trypsin like enzyme(s).

Amino Acid Sequence↗
PubMed1987

Effect of bucindolol on plasma HDL cholesterol subfractions and other plasma lipids in essential hypertensive patients.

The effect on plasma lipids of a new beta-blocker bucindolol, which possesses weak alpha-adrenergic blocking property and intrinsic sympathomimetic activity, given orally over a 3-month period as a monotherapy or with a thiazide diuretic to 44 patients with essential hypertension was studied. The mean level of plasma HDL cholesterol concentration increased significantly during 3 months monotherapy with bucindolol or with bucindolol and diuretic. This increase was due to the increase of HDL3 subfraction. There were no significant changes in the concentrations of plasma triglycerides or total cholesterol during treatment. The ratio of HDL cholesterol to total cholesterol increased significantly. The concentration of apoprotein A-I decreased significantly in both treatment groups, but the level of apoprotein B remained constant among treatment groups. The results support the earlier observations that beta-adrenergic blocking agents with different pharmacologic properties differ as regard to their effects on plasma lipids and lipoproteins.

Adrenergic beta-Antagonists↗
PubMed1977

Plasma LH and FSH response to LRH and plasma testosterone levels in boys with irregular puberty.

Nineteen boys with irregular puberty (IP), defined as a discrepancy of two or more pubertal stages between the criteria for genitalia and that for pubic hair, were subjected to a standard LRH test (50 microng/m2, iv) and the response of gonadotrophins as well as the basal levels of plasma testosterone, LH and FSH were compared to those of boys with normal, regular puberty. When the results were plotted against the pubertal stage for genitalia (Pg), it was found that in the boys with IP the basal plasma testosterone levels were lower and the response of plasma LH to LRH stimulation lesser than in the controls. However, when these parameters were plotted against the pubertal stage for pubic hair (Ph) it was found, that in the boys with IP the plasma testosterone levels were significantly higher and the response of both LH and FSH stimulation greater than in the control group. It was concluded that irregular puberty in boys may be regarded as a normal variation. The delayed development of sexual hair and penile length, and retarded pubertal growth spurt and bone age maturation seen in these boys, with normal testicular development, may be explained by a temporary reduced peripheral sensitivity to androgens and a compensatory effort by the pituitary, manifested in increased secretion of LH and testosterone, relatively to their pubertal stage for pubic hair.

Adolescent↗
PubMed1988

Hemodynamics, plasma eicosanoid concentrations, and plasma biochemical changes in calves given multiple injections of Escherichia coli endotoxin.

Twelve male neonatal calves (39 to 50 kg) were allotted to 3 groups of 4 calves each. All calves were anesthetized with halothane, and then Escherichia coli endotoxin was given intravenously (3 times) and intraperitoneally (3 times) during a 6-hour period. Group-1 calves were untreated, group-2 calves were pretreated with a low dose of flunixin meglumine (1.1 mg/kg of body weight), and group-3 calves were pretreated with a high dose of flunixin meglumine (4.4 mg/kg). In calves of group 1, the mean systemic arterial blood pressure (MABP) and cardiac output (CO) decreased, but pulmonary arterial pressure increased after the initial intravenous and intraperitoneal injections of endotoxin. In calves of this group, these changes were accompanied by increased plasma thromboxane B2 (TxB2) concentration. During this period, increased plasma TxB2 concentration or hemodynamic changes were not detected in calves of groups 2 and 3. Only calves of group 1 had altered hemodynamics early in the experiment; however, after 6 hours, calves of all 3 groups had similarly decreased CO and MABP. In calves of the untreated group, plasma 6-keto-prostaglandin (PG)F1 alpha concentration increased steadily from the beginning of the experiment until 3 hours later. The CO and MABP were low at the time when serum 6-keto-PGF1 alpha concentration was high; however, these 2 measurements also were low in treated calves who did not have correspondingly high plasma 6-keto-PGF1 alpha concentration. Regional blood flow analysis did not reveal correlations between prostanoid concentrations and altered blood flow to selected tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Intracellular precursor forms of plasma proteins: their functions and possible occurrence in plasma.

An attempt is made to review the steps in the biosynthesis of plasma proteins by the liver and to point out intermediate precursor forms that might escape to the plasma. With the use of immunochemical techniques such as immunofixation electrophoresis it is possible to identify these precursors when they present an unusual bands on protein electrophoresis. The discovery of the role of vitamin K in the formation of the blood-clotting proteins, for example, followed the immunochemical detection of an abnormal form of inactive prothrombin in plasma. The chief types of precursors likely to occur in blood are forms that are incompletely glycosylated, phosphorylated, or sulfated, or which are single peptide chains of multichain proteins. Precursors containing basic propeptides such as proinsulin or proalbumin may also appear. By being alert to the possible appearance of intracellular forms in plasma, the clinical chemist may be able to relate their presence to the nature of the disease process responsible.

Animals↗
PubMed1987

Dilution of plasma with Tris buffer increases measured catecholamines in plasma.

We investigated the effects of dilution of plasma samples on the measured concentrations of catecholamines. Diluting samples of human plasma 10-, 50-, and 100-fold with Tris buffer (100 mol/L, pH 8.6) improved analytical recovery of internal standards, suggesting that it decreases the commonly observed inhibition of methylation in radioenzymatic assays of catecholamines in plasma. However, the dilution is not associated with a proportional decrease in counted radioactivity. This extra amount of radioactivity, which is unlikely to be nonspecific in origin, accounts for a significant increase in the calculated catecholamine concentration. Tentatively, we suggest that Tris buffer releases both catecholamines and conjugated catecholamines bound to some unidentified low-molecular-mass component of plasma.

Dopamine↗
PubMed1987

Quantification of desferrioxamine in blood plasma by inductively coupled plasma atomic emission spectrometry.

A sensitive method, inductively coupled plasma atomic emission spectroscopy, is used to measure desferrioxamine in blood plasma. The desferrioxamine is transformed into its iron chelate, ferrioxamine, which is extracted into benzyl alcohol, then re-extracted into HCl (0.5 mol/L), which is used as the sample for the spectroscopy. For a 0.5-mL plasma sample, the detection limit (1 microgram/mL) suffices for following the concentration of desferrioxamine in plasma after its subcutaneous or intramuscular injection (40 mg per kg of body weight). Neither blood pigments nor trace metals interfere.

Colorimetry↗