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Biomedical subjects

N D Vaziri

Publications and source records attributed to N D Vaziri.

At least 19 recordsLinked to original sources
PubMed1992

Plasma concentration and urinary excretion of erythropoietin in adult nephrotic syndrome.

PURPOSE: Nephrotic syndrome (NS) is associated with a significant alteration of protein metabolism. While lowering the plasma concentrations of certain proteins, the disease often raises the level of certain other proteins. The current study was undertaken to determine the effect of NS on erythropoietin (EPO) metabolism. PATIENTS AND METHODS: We measured the EPO concentration in plasma and urine of 26 patients with NS by an immunologic assay using a rabbit antiserum against recombinant human EPO. The results were compared with those obtained in a group of 12 normal control subjects. RESULTS: Despite a significant reduction in the hemoglobin concentration in the NS group compared with the control group (125 +/- 25 g/L versus 148 +/- 11 g/L, p less than 0.05), the plasma EPO concentration in the NS group was not significantly different from that seen in the control group (6.2 +/- 4.5 mU/mL versus 6.7 +/- 2.4 mU/mL, p = NS). No significant correlations were found between plasma EPO and hemoglobin concentration, serum creatinine, serum albumin, or urinary albumin excretion rate. Moreover, comparison of the NS patients with serum creatinine concentrations less than or equal to 1.5 mg/dL (133 mumol/L) with those exhibiting creatinine concentrations exceeding 1.5 mg/dL did not reveal a significant difference in mean plasma EPO concentration. Significant amounts of EPO were found in the urine of the patients with NS, while none was detected in the urine of the control subjects. CONCLUSION: We conclude that plasma EPO is inappropriately low in patients with NS. This is due, at least in part, to the urinary/renal losses of this protein and can potentially contribute to anemia in NS patients or compound the problem in those with concurrent renal insufficiency and diminished EPO production.

Adolescent↗
PubMed1992

Coagulation, fibrinolytic, and inhibitory proteins in acute myocardial infarction and angina pectoris.

BACKGROUND AND METHOD: The role of thrombus formation in the pathogenesis of acute myocardial infarction (AMI) and unstable angina pectoris has been well established. However, comprehensive and systematic studies of the blood coagulation, fibrinolytic, and inhibitory proteins are not available in patients with these conditions. Fourteen patients with AMI, 10 patients with angina pectoris, and 32 normal volunteers were studied. Plasma antigen concentrations and/or activities of high-molecular-weight kininogen (HMWK), fibrinogen, fibronectin, plasminogen, D-dimer, tissue plasminogen activator (t-PA), alpha 2-antiplasmin, alpha 2-macroglobulin, alpha 1-antitrypsin, protein C, total and free protein S, antithrombin III (AT-III), von Willebrand factor (vWF), factors (F) XII, XI, IX, VIII, VII, X, V, II, and XIII, and plasma antiplasmin activity were measured using appropriate functional or immunologic assays. RESULTS: The AMI group showed a significant reduction in F XII activity, F XII activity-to-concentration ratio, and HMWK concentration. In addition, the AMI patients exhibited a significant elevation of plasma F XI activity, F IX concentration, and F IX activity, and vWF, fibrinogen, D-dimer, and t-PA concentrations. This was associated with significant reductions in F V, F II, and AT-III activity-to-concentration ratio. Many of the changes observed in AMI patients were also present in patients with angina pectoris. Furthermore, the latter group exhibited an elevation of F VIII activity, alpha 2-macroglobulin activity, and alpha 1-antitrypsin concentration and a significant reduction of antiplasmin activity despite a normal alpha 2-antiplasmin concentration. CONCLUSIONS: The observed reduction of the plasma F XII activity-to-antigen concentration ratio combined with a reduced HMWK concentration suggests intrinsic pathway activation, while the elevation of the D-dimer concentration indicates thrombin generation and fibrin formation and degradation in the AMI group. The latter changes were also present in patients with angina pectoris. Both AMI and angina groups showed several other abnormalities of the coagulation, fibrinolytic, and inhibitory systems. The results suggest the presence of a prothrombotic state associated with the activation of coagulation and fibrinolytic systems in patients with acute myocardial ischemia or infarction.

Adult↗
PubMed1992

Increased glomerular atrial natriuretic peptide receptor affinity in experimental nephrotic syndrome.

Atrial natriuretic peptide (ANP) is a cardiac hormone with natriuretic and diuretic effects. To better define the ANP hormonal system in the nephrotic syndrome, a condition associated with renal sodium retention, we undertook a study of glomerular ANP receptors in rats with puromycin aminonucleoside-induced nephrotic syndrome and in pair-fed controls. Nephrotic rats had significantly decreased serum albumin and total protein and significantly increased serum cholesterol, triglycerides and 24 hour urinary protein excretion. Plasma level of atrial natriuretic peptide was similar in both groups of rats. Competition binding inhibition studies in isolated glomeruli demonstrated one binding site in both groups of rats. The density of ANP binding sites in isolated glomeruli was similar in nephrotic and pair-fed rats while the binding affinity was increased significantly in the nephrotic rats. This is the first study to demonstrate alterations in renal ANP receptors in the nephrotic syndrome. Further studies will be necessary to determine whether alterations in glomerular ANP receptors contribute to renal sodium retention in the nephrotic syndrome.

Animals↗
PubMed1992

Effective portal insulin delivery with enzyme-protected capsules in pancreatectomized pigs.

1. Plasma concentrations of insulin, C-peptide, glucagon and glucose were measured in surgically pancreatectomized pigs given insulin into the colon directly and in enteric peptidase-resistant (methacrylic acid copolymer-encapsulated) form. 2. Following introduction of insulin-containing capsules, plasma insulin concentration rose from 2.7 +/- 0.1 microU/ml to 110.9 +/- 51.9 microU/ml in the portal vein, and from 2.6 +/- 0.1 microU/ml to 26.9 +/- 7.3 microU/ml in the systemic circulation. Corresponding portal and systemic values after direct (non-encapsulated) insulin instillation were 28.2 +/- 15.9 microU/ml to 44.8 +/- 13.0 microU/ml and 7.5 +/- 2.6 microU/ml to 15.2 +/- 2.5 microU/ml respectively. Insulin concentrations peaked at 75 min in the group as a whole and between 60-90 min in individual animals. Absorption was most pronounced in pigs given aprotinin (a trypsin inhibitor) with insulin. 3. Plasma portal vein glucose concentrations fell from 76.2 +/- 8.9 mg/dl to 31.1 +/- 3.2 mg/dl 150 min after encapsulated insulin administration. Corresponding systemic glucose levels were 84.5 +/- 11.0 mg/dl and 37.0 +/- 1.4 mg/dl. 4. Colonic administration of insulin in methacrylic acid coated capsules results in peak portal and systemic insulin levels 60-90 min after administration. Co-administration of aprotinin enhances the fraction of insulin absorbed.

Animals↗
PubMed1992

Erythropoietin metabolism and pharmacokinetics in experimental nephrosis.

We studied erythropoietin (EPO) metabolism, regulation, and pharmacokinetics in rats with nephrotic syndrome. Sprague-Dawley rats were randomized into nephrotic (puromycin-induced) and pair-fed control groups. Animals were studied at baseline and after induction of anemia or exposure to hypobaric conditions (32 cmHg). The nephrotic group showed a reduced hematocrit (P < 0.05), a significant urinary EPO excretion, and an inappropriately low plasma EPO. Induction of anemia and exposure to hypoxia resulted in a less pronounced elevation of plasma EPO in the nephrotic group than in the control group (P < 0.05). The blunted plasma EPO response to hypoxia in nephrotic animals was associated with a marked rise in urinary EPO excretion. Pharmacokinetic studies following intravenous injection of recombinant EPO, 100 U/kg, revealed a shorter plasma half-life (t1/2) (P < 0.05), larger apparent volume of distribution (P < 0.05), and greater clearance (P < 0.02) in the nephrotic group than in the controls. Estimated endogenous EPO production rate in nephrotic rats with severe anemia was significantly lower (P < 0.05) than that of equally anemic controls. Thus puromycin-induced nephrotic syndrome is associated with marked urinary loss of EPO, relatively depressed plasma EPO response to anemia and hypoxia, as well as reduced plasma t1/2, increased volume of distribution, and clearance of exogenous EPO.

Anemia↗
PubMed1992

The pituitary-gonadal axis in experimental nephrotic syndrome in male rats.

Basal and luteinizing releasing hormone-stimulated gonadotropin secretion were studied in male rats made nephrotic with puromycin, and in pair-fed and normal control animals. In addition, plasma concentrations of testosterone, androstenedione, estradiol, and estrone were measured in the three groups of animals. Urinary testosterone concentrations were also measured in the three experimental groups. The data showed that basal luteinizing hormone concentration was significantly elevated in the nephrotic group compared with the pair-fed and normal control groups. Gonadotropin response to luteinizing releasing hormone stimulation was not significantly different in the three groups, suggesting an intact hypothalamic-pituitary axis in nephrotic syndrome. Urinary testosterone concentration in the nephrotic animals was significantly higher than in the pair-fed and normal control groups. Plasma testosterone, androstenedione, estradiol, and estrone concentrations were significantly lower in the nephrotic and pair-fed animals than in the normal control animals, indicating possibly impaired gonadal steroidogenesis in these two groups that may be related to the catabolic state of the animals. It thus appears that urinary loss of protein-bound (sex hormone binding globulin-bound) testosterone in the nephrotic syndrome leads to increased basal secretion of luteinizing hormone, presumably as a result of increased luteinizing releasing hormone secretion. This occurs to compensate for the abnormal urinary testosterone loss and is an attempt to restore plasma testosterone concentrations to normal. The higher basal plasma luteinizing hormone concentration in the nephrotic group supports this conclusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Pressure ulcer, fibronectin, and related proteins in spinal cord injured patients.

Pressure ulcer is a common occurrence in spinal cord injured (SCI) patients and can lead to serious complications. With proper management, some patients exhibit satisfactory healing whereas others show slow or nonhealing ulcers. Fibronectin has been shown to accumulate in wound, opsonize macroaggregate debris for phagocytosis, promote revascularization, and facilitate fibroblast migration and proliferation. We explored the relationship of plasma fibronectin with healing potential in 21 SCI men with pressure ulcer. They received standard wound care and were observed for eight weeks. Ten otherwise healthy SCI men without pressure ulcer (SCI-controls) and 32 able-bodied normal individuals (normal controls) were also studied. Plasma fibronectin and related proteins, ie, fibrinogen, plasminogen, alpha 2-antiplasmin and Factor XIII, were measured. Ten of 21 SCI patients with pressure ulcer showed rapid healing within four weeks and had significantly higher fibronectin levels as compared with the 11 patients with poor healing ulcers, SCI controls, and normal controls. Factor XIII and alpha 2-antiplasmin were mildly reduced and fibrinogen values were significantly increased in all SCI groups. Plasminogen concentrations were comparable in all groups studied. It thus appears that plasma fibronectin rises in patients with fast healing ulcers but fails to do so in those with poor healing ulcers and as such may be predictive of the course of pressure ulcers.

Adult↗
PubMed1992

Effect of chronic renal failure on intestinal transport of biotin in the rat.

The present study examined the effect of chronic renal failure (RF) on biotin transport in rat intestine. Chronic RF was induced by subjecting rats to right nephrectomy and left two-thirds nephrectomy. Control rats underwent sham operation but without tissue removal and were pair fed. Transport studies were performed 5 to 6 weeks after operation. Chronic RF was found to cause a marked decrease in the maximal velocity (Vmax) of biotin mucosal-to-serosal transport in jejunal everted sacs with minimal change in the apparent Michaelis-Menten constant (Km) of the transport process. This impairment in biotin transport was found to involve the transport process of the vitamin across the brush border membrane (BBM) domain of the enterocyte as shown by studies with BBM vesicles (BBMVs). These studies with BBMV similarly showed a decrease in the Vmax of biotin transport with minimal change in the apparent Km. The impairment of biotin transport in intestinal BBMVs was not due to dissipation of the Na+ gradient across the BBM (which is the driving force of biotin movement across this membrane) because transport of sodium 22 was found to be similar in BBMVs prepared from the RF rats and the sham-operated PF control rats. These results demonstrate that chronic RF in rats causes impairment in biotin intestinal transport. This impairment is due to a decrease in the number (and/or activity) of the biotin transport carriers and involves the transport process of biotin at the BBM.

Animals↗
PubMed1992

Blood coagulation, fibrinolytic and inhibitory profiles in renal transplant recipients: comparison of cyclosporine and azathioprine.

Renal transplant recipients treated with cyclosporine (CS) have been reported to be at increased risk of thrombotic complications. The present study was intended to examine the blood coagulation, fibrinolytic, and inhibitory systems in such patients. Eight transplant recipients on maintenance immunosuppression with CS and prednisone were studied. Five transplant recipients maintained on azathioprine (AZA) and prednisone and 32 normal volunteers served as controls. Plasma antigen concentrations and/or activities of various proteins in the above pathways were measured. Both the CS and AZA groups exhibited significant elevations of factor IX activity, von Willebrand factor (vWF), D-dimer, protein C and tissue type plasminogen activator (t-PA) levels when compared with the normal controls. In addition, CS group showed a significant elevation of alpha 2-macroglobulin activity and AZA group showed a significant reduction in factor XII activity when compared with the normal controls. Comparison of data from CS and AZA groups revealed higher factor XII activity and vWF concentration in the former group. In conclusion, transplant recipients treated with long-term cyclosporine and prednisone exhibited significant elevation of plasma vWF, D-dimer and protein C concentrations. In addition, both CS and AZA-treated transplant recipients showed increased plasma concentrations of D-dimer and t-PA. The latter observations suggest in vivo thrombin generation, fibrin formation and degradation.

Adult↗
PubMed1991

Intestinal absorption of linoleic acid in experimental renal failure.

Linoleic acid (LA) transport in rats with experimental short-term and long-term renal failure (RF) was compared with that of sham-operated normal animals on liberal food intake and pair-fed animals. The perfusions in vivo and incubations in vitro were conducted using a micellar solution containing a wide range of LA concentrations. Both absorption in vivo and uptake in vitro of LA were significantly reduced in animals with short-term RF. Lipid extraction and separation by thin-layer chromatography revealed a marked LA trapping as trilinolein (TL) in the perfused intestinal tissue in the short-term RF group. The esterification process, as defined by the rate of LA incorporation into TL, was moderately reduced in short-term RF animals. The thickness of the unstirred water layer showed no significant difference among the groups studied. In contrast, animals with long-term RF exhibited normal absorption of LA in vivo at all concentrations tested. In conclusion, LA absorption is reduced in short-term RF and restored in long-term RF. Several steps including LA transport into and TL transport out of the enterocyte and the esterification process were impaired in short-term RF. These changes are not due to alteration in the unstirred water layer, anorexia, weight loss or a rapid effect of uraemic chemical environment or circulatory factors.

Animals↗
PubMed1991

Glomerulopressin activity in carbon tetrachloride-induced cirrhosis in male rats.

The activity of glomerulopressin, a putative renal vasoregulatory hormone that is synthesized in the liver, was assayed in male rats with carbon tetrachloride-induced cirrhosis and the results were compared to glomerulopressin activity in normal-control and pair-fed animals. Glomerulopressin activity in blood samples collected from the hepatic vein of the cirrhotic group was significantly lower than the activity in the normal-control and pair-fed groups. Glomerulopressin activity in the normal-control and the pair-fed groups were not significantly different. The data support the concept that glomerulopressin deficiency in liver disease, such as cirrhosis, may play a role in the genesis of the functional renal failure associated with liver disease.

Animals↗
PubMed1991

Vitamin D absorption, plasma concentration and urinary excretion of 25-hydroxyvitamin D in nephrotic syndrome.

Nephrotic syndrome (NS) is commonly associated with vitamin D deficiency. Urinary losses of the protein-bound intermediary metabolite of this vitamin is thought to contribute to the deficiency state. The role of possible changes, if any, of vitamin D absorption has not been investigated previously in NS. We determined intestinal absorption of vitamin D3 as well as plasma concentration and urinary excretion of 25-hydroxyvitamin D3 in rats with puromycin aminonucleoside-induced NS. In vivo recirculating perfusion technique was employed at 100 and 600 nM perfusate concentrations. The results were compared with those obtained in animals receiving placebo injections provided with either free access to food (normal controls) or those pair-fed with their NS counterparts (pair-fed group). The NS group showed heavy proteinuria and hypoalbuminemia. In addition, the NS group exhibited marked urinary losses and significantly reduced plasma concentration of 25-hydroxyvitamin D. The rate of vitamin D3 absorption (given as nmol/100 cm/min) at 100 nM perfusate concentration in the NS group (0.161 +/- 0.029) was not significantly different from those obtained in the pair-fed group (0.202 +/- 0.058) and the normal control group (0.143 +/- 0.053). Likewise, no significant difference was found in the rats of vitamin D absorption at 600 nM concentration among the NS (1.073 +/- 0.383), pair-fed (0.955 +/- 0.229), and normal control (0.756 +/- 0.314) groups. Accordingly, intestinal absorption of vitamin D appears to be unaffected by the presence of experimental NS and as such the associated vitamin D deficiency can be managed by enteral supplementation.

Absorption↗
PubMed1991

Erythropoietin in preeclampsia.

To investigate the possible effect of preeclampsia on erythropoietin metabolism, we measured plasma and urine erythropoietin concentrations and complete blood count in 19 women with preeclampsia and nine healthy gravidas. Hemoglobin concentration and hematocrit values in the preeclamptic patients did not differ significantly from those of the normal pregnant controls. However, the plasma erythropoietin concentration tended to be higher in the preeclamptic group than in the normal pregnant controls (26.9 +/- 31.2 versus 11.2 +/- 9.9 mU/mL), though the difference was not statistically significant. Plasma erythropoietin concentration correlated negatively with both hemoglobin concentration and hematocrit (r = -0.85, P less than .01). The pattern and magnitude of the erythropoietin response to anemia paralleled that previously reported in individuals with iron deficiency anemia. No significant correlation was found between urinary erythropoietin excretion and blood pressure, qualitative albumin excretion, hematocrit, hemoglobin concentration, or plasma erythropoietin concentration. Based on our results, the erythropoietin response to anemia appears to be intact in preeclampsia, at least in the absence of renal failure.

Adult↗
PubMed1991

Factor XIII and its substrates, fibronectin, fibrinogen, and alpha 2-antiplasmin, in plasma and urine of patients with nephrosis.

Plasma and urine concentrations of factor XIII and its circulating substrates (fibronectin, fibrinogen, and alpha 2-antiplasmin) were measured in a group of 36 patients with nephrotic syndrome. The results were compared with those obtained in a group of 32 normal volunteers (control group) and 12 patients with end-stage renal disease (ESRD). A mild but significant reduction in plasma level and an abnormal urinary excretion of alpha 2-antiplasmin was found in the nephrotic group. Plasma concentrations of factor XIII, fibronectin, and fibrinogen were significantly elevated in patients with nephrosis. In contrast, patients with ESRD showed no significant difference in the plasma concentrations of either factor XIII, fibronectin, or alpha 2-antiplasmin and only a modest elevation of fibrinogen when compared with normal controls. No significant correlation was found between serum creatinine concentration and plasma levels of factor XIII and its circulating substrates in the nephrotic group. No measurable quantities of factor XIII and only small quantities of fibronectin were found in the urine of patients with nephrosis. Elevation of plasma factor XIII, fibronectin, and fibrinogen concentrations in the nephrotic group is considered to be the result of a combination of increased synthesis and possibly contracted intravascular distribution of these macromolecular proteins in the face of their negligible urinary losses. The presence of the observed abnormalities in the nephrotic group and their absence in the non-nephrotic ESRD group tends to exclude renal failure as a cause of these abnormalities. Although the clinical significance of these abnormalities is uncertain, they can potentially contribute to the thrombophilic diathesis and platelet hyperaggregability in nephrotic syndrome.

Adolescent↗
PubMed1991

Functional, biochemical, and histopathologic consequences of high-dose interleukin-2 administration in rats.

A variety of side effects have been reported with the use of interleukin-2 alone or in combination with lymphokine-activated killer cells in patients with disseminated neoplasms. The present study was undertaken to determine the effects of high-dose interleukin-2 administration in normal rats. Sprague-Dawley rats were treated with intravenous recombinant interleukin-2 (900,000 IU/kg/day) for 9 consecutive days. Animals were placed in individual metabolic cages, and arterial blood pressure, food intake, body weight, and urine output were monitored. On day 10, animals were killed by exsanguination, various tissues were harvested, and a variety of hematologic and chemical assays were performed. The results were compared with those of placebo-injected normal control and pair-fed groups. The interleukin-2-treated group exhibited anorexia, weight loss, hypotension, anemia, leukocytosis, lymphocytosis, eosinophilia, hypercalcemia, azotemia, and a marked urinary concentration defect. Histologic examination of various tissues revealed widespread infiltration with mono-nuclear cells and eosinophils in most organs, especially in the lungs and liver of interleukin-2-treated animals. Other abnormalities included severe panlobular hepatitis, hepatocellular necrosis, and thymic involution. Renal involvement was mild and consisted of focal interstitial infiltration by mononuclear cells. According to these observations, administration of high-dose interleukin-2 in normal rats results in a score of significant functional, biochemical, and histologic abnormalities.

Anemia↗