A receptor assay for serum low density lipoprotein-apolipoprotein B-100: preliminary report.
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Apolipoprotein B-100↗
Biomedical subjects
N Rifai
Publications and source records attributed to N Rifai.
Lead poisoning in young children in Washington, DC: a crisis that remains to be addressed.
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Child↗
Lipoprotein(a) at birth, in blacks and whites.
It has been shown that blacks have considerably higher concentrations than whites of lipoprotein(a) (Lp(a)), which has been identified as an independent risk factor for coronary heart disease, vein graft restenosis, and cerebrovascular disease. Smaller differences in Lp(a) concentrations have been noted between males and females. To examine whether gender and race differences are already detectable at birth, we examined Lp(a) concentrations in cord blood samples of 109 black (49 male and 60 female) and 123 white (67 male and 56 female) newborns. Maternal age, gestational age, fetal maturity indicators, weight, height and head circumference were analyzed as covariates. For race and sex combined, the mean Lp(a) concentration was 4.0 mg/dl (S.D. of 3.94 mg/dl), approximately 5-fold lower than that observed in adults. No statistically significant differences were found between race or gender groups. The cross-sectional examination of serum Lp(a) concentrations of 221 infants, children and adults showed a gradual increase in Lp(a) concentrations from birth to adult values by the second year of life. We conclude that the system responsible for the production and control of Lp(a) concentration is not yet mature--or has not yet been challenged--at birth.
Black People↗
Development of a radioreceptor assay to measure glucocorticoids.
We have developed a radioreceptor assay to measure glucocorticoids. The assay employs the partially purified 95-kDa receptor isolated from human liver and purified by size fractionation on high-performance liquid chromatography (HPLC). In the assay [3H]prednisolone competes with steroids (endogenous and exogenous) for binding to the receptor. Bound and free are separated by treatment with charcoal. The between-day precision [% coefficient of variation (CV)] at concentrations of 9.4, 18.7, and 69.9 micrograms/L prednisolone is 16.6, 9.3 and 4.5%, respectively. Specificity studies revealed that hydrocortisone, deoxycorticosterone, 4-pregnene-17 alpha,21-diol-3,20-dione, 17 alpha-hydroxyprogesterone, corticosterone and beta-hydroxyprogesterone all compete with [3H]prednisolone for binding to the receptor. Prednisone and 6 alpha-methyl prednisolone displace [3H]prednisolone to only a minor degree. The assay has been used to assess "glucocorticoid activity" in children with rheumatic diseases treated with prednisolone.
Charcoal↗
Organic acids interfere in the measurement of carbon dioxide concentration by the Kodak Ektachem 700.
A significant discrepancy was noted in our laboratory between the total plasma carbon dioxide concentration measured by the Kodak Ektachem 700 and the bicarbonate concentration derived from the Corning 170 pH/Blood Gas analyser in an 8-day-old patient. The concentration of total carbon dioxide was 18 mmol/L while the derived bicarbonate was 13 mmol/L. The patient was eventually diagnosed as maple syrup urine disease. This finding led us to examine the effect of various organic acids on the measurement of carbon dioxide by the Ektachem 700. Several interfered significantly. Clinicians should be aware that when organic acid concentrations are increased, the Ektachem 700 total carbon dioxide result may be falsely raised.
Blood Gas Analysis↗
Measurement of low-density-lipoprotein cholesterol in serum: a status report.
Current recommendations of the Adult Treatment Panel and the Children and Adolescents Treatment Panel of the National Cholesterol Education Program make the concentration of low-density lipoproteins cholesterol (LDL-C) in serum the basis for the classification and treatment of hypercholesterolemia. Numerous methodologies for the determination of serum LDL-C concentrations, in research and clinical laboratories, have been described. Here, we review the principles, performance, and limitations of major current methodologies for determining LDL-C concentrations. These methods include sequential and density-gradient ultracentrifugation, chromatographic and electrophoretic techniques, and precipitation methods. In addition, the advantages and disadvantages of estimating LDL-C concentration by the Friedewald equation, the most commonly used approach in clinical laboratories, are addressed.
Chemical Precipitation↗
Stress reactivity and exercise training in premenopausal and postmenopausal women.
Examined the influence of ovarian function on psychophysiological stress responses and determined if aerobic exercise reduced stress reactivity. Fifty premenopausal and postmenopausal women initially were subjected to a public speaking task and an ice-on-the-forehead procedure, during which time their blood pressure and heart rate were monitored and continuous blood samples were obtained. Subjects also underwent aerobic fitness evaluations with a maximum-exercise treadmill test. Subjects were then randomly assigned to a 12-week exercise program of either aerobic exercise (e.g., walking and jogging at a prescribed exercise intensity) or non-aerobic strength and flexibility training and were then reevaluated. Results indicated that postmenopausal women exhibited lower resting epinephrine levels but greater epinephrine reactivity to the speaking task compared to the premenopausal women. There were no differences between premenopausal and postmenopausal women with respect to cardiovascular or catecholamine responses during the cold challenge. Premenopausal and postmenopausal women also achieved comparable improvements in aerobic fitness. However, results of the mental stress testing were complex and provided only partial support for the role of aerobic exercise in reducing stress responses.
Arousal↗
Role of the clinical laboratory in evaluation of argininosuccinate lyase deficiency.
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Amino Acids↗
Cholesterol testing in the physician's office: accuracy assessment.
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District of Columbia↗
Beta 2-microglobulin and neopterin: predictive markers for human immunodeficiency virus type 1 infection in children?
The value of beta 2-microglobulin and neopterin concentrations in serum for early diagnosis of infants born to human immunodeficiency virus type 1 (HIV-1)-infected mothers was assessed. Concentrations of both markers were measured in serum samples from pediatric patients (Centers for Disease Control classifications P0, P1, and P2), as well as in age-matched normal subjects. Both beta 2-microglobulin and neopterin were significantly increased in HIV-1-infected symptomatic subjects (P2) compared to controls. Seventy-five percent of asymptomatic patients (P1) also had increased values. On the other hand, a significant overlap in concentrations of both markers in serum was found between controls and P0 patients. Thirty-eight percent of the P0 patients had values comparable to those of the P2 group. Persistently high concentrations of both markers in P0 patients may be indicative of HIV-1 infection.
Biomarkers↗
Postprandial effect of a high fat meal on plasma lipid, lipoprotein cholesterol and apolipoprotein measurements.
We investigated the effect of a fatty meal on plasma concentrations of lipids, apolipoproteins, and the cholesterol component of lipoproteins. Sixteen nonobese, healthy, asymptomatic males, 22-34 years of age, served as subjects for this study. None smoked, consumed more than two alcoholic drinks per day, or took any medication known to alter plasma lipids. After a 12 h fast, baseline plasma samples were obtained just before subjects consumed a high fat meal. The meal, standardized to a 70 kg individual, contained approximately 70 g fat, 580 mg cholesterol, and 1,100 cal, with 56% of the calories coming from fat. During the 8 h following consumption of the meal, subjects rested quietly and consumed no food or beverages except water. Blood specimens were obtained hourly. There was a significant increase in plasma triglyceride (150% from baseline at 3 h, P less than 0.0005). Very low density lipoprotein cholesterol (VLDL-C) concentrations increased 150% at 3 h (P less than 0.0005) while low density lipoprotein cholesterol (LDL-C) concentration decreased 37% at 3 h (P less than 0.005) when estimated by Friedewald's formula. No statistically significant differences were observed between fasting total cholesterol, high density lipoprotein cholesterol (HDL-C). HDL2-C, and HDL3-C, apolipoprotein AI (apo AI, AII), and B-100 concentrations and non-fasting samples. We conclude that plasma triglyceride concentration is significantly affected in the post-prandial state. As a result, VLDL-C and LDL-C when assessed by the Friedewald formula are also altered. A minimum of 8 h fasting is required to assess these concentrations accurately in this population.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
[Role of beta-2-mimetic agents in the treatment of asthma].
Recent modifications of pre existing Beta 2 drugs and new substances with a prolonged bronchodilator effect may improve asthmatic treatment, in term of duration of benefit and compliance to medication. Evaluation of bronchodilation is still debated. When single dose of drug is administered, nycthemeral rhythm, baseline pulmonary function are to be taken in account. In case of long term treatment studies, evaluation of the effects is based upon clinical score, sequential pulmonary function tests, morning and evening peak expiratory flow rates. Risks way be related to be related to beta 2 drugs or concomitant therapy or associated pathology. Indications of dose and route administration are related to asthma severity. Question to state if beta 2 drugs may be considered as prevention treatment. Studies with compounds exhibiting prolonged bronchodilating effect are able to reduce nocturnal asthma, peak flow instability and to improve clinical scores and pulmonary function.
Administration, Oral↗
Biochemical effects of 17 beta-estradiol on UMR106 cells.
The effect of 17 beta-estradiol (E) on an osteoblast-like cell line, UMR106, was studied in vitro. The concentrations of transferrin and seven enzymes (gamma glutamyl transferase, alkaline phosphatase, acid phosphatase, lactate dehydrogenase, creatine kinase, alanine aminotransferase and aspartate aminotransferase) were measured in these cells after incubation in culture medium containing either E or the vehicle. E treatment increased five of the seven enzymes and increased the transferrin concentration in the UMR106 cells while simultaneously reducing the proliferation rates. 4-Hydroxytamoxifen, an estrogen antagonist, produced a mild estrogen agonist action on growth rates and enzyme concentrations in the UMR106 cells. When E was present simultaneously, the agonist properties of 4-hydroxytamoxifen were enhanced. These studies show that E enhanced activity of five enzymes and the transferrin content of UMR106 cells after a 2-day incubation. 4-Hydroxytamoxifen enhanced the E effect, illustrating that estrogen antagonists may manifest agonist or antagonist properties depending on the model. These results extend our previous observations showing a direct effect of E in vitro on osteoblast-like cells.
Acid Phosphatase↗
Protracted anemia associated with chronic, relapsing systemic inflammation induced by arthropathic peptidoglycan-polysaccharide polymers in rats.
Mild hypoproliferative anemia with abnormal iron metabolism frequently accompanies chronic inflammation and infection in humans. To determine whether anemia is associated with chronic relapsing arthritis induced by bacterial cell wall polymers, serial determinations of the hematocrit were measured in rats injected intraperitoneally with sonicated peptidoglycan-polysaccharide fragments from group A streptococci. Acute anemia peaked 5 to 10 days after injection, and chronic, spontaneously relapsing anemia persisted for 309 days. 51Cr labeling demonstrated decreased erythrocyte survival, i.e., a half-life of 8.4 days in cell wall-injected rats versus 11.8 days in controls. Erythrocytes were mildly microcytic, and leukocyte counts were elevated during early spontaneous reactivation of arthritis, 15 days after injection of peptidoglycan-polysaccharide. Bone marrow myeloid/erythroid precursor ratios were elevated in arthritic rats (P less than 0.0001). Purified peptidoglycan produced an acute anemia lasting 10 days, while injection of group A streptococcal polysaccharide and mutanolysin-digested cell wall did not affect the hematocrit. The minimal effective dose of peptidoglycan-polysaccharide was 5 micrograms of rhamnose per g (body weight). Serum iron and transferrin levels were decreased in cell wall-injected rats (P less than 0.005) and were closely correlated with hematocrit values and joint inflammatory scores. Stainable iron was increased in the liver, spleen, and mesenteric lymph nodes and unchanged in the bone marrow of cell wall-injected rats. Anemia accompanying chronic, relapsing systemic inflammation induced by peptidoglycan-polysaccharide polymers appears to be an excellent animal model of the anemia of chronic disease.
Anemia↗
Immunoturbidimetry of beta 2-microglobulin in serum.
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Humans↗
Measurement of methsuximide and N-desmethylmethsuximide using solid-phase extraction and wide-bore capillary gas chromatography.
A method for the determination of the anti-epileptic drug methsuximide (MSM) and its active metabolite N-desmethylmethsuximide (NDM) is presented. 5-Methyl-5-phenylhydantoin is used as the internal standard. A simple solid-phase extraction procedure utilizing disposable reversed-phase C18 columns is described. Samples are analyzed by gas chromatography with flame ionization detection using a wide-bore capillary column with a permanently bonded, non-polar stationary phase. The MSM assay possesses linearity to 6.0 micrograms/mL, sensitivity to 0.5 microgram/mL, recovery ranging from 93 to 110%, and precision reflected by a SD of +/- 0.37 microgram/mL. The NDM assay displays linearity up to 80.0 micrograms/mL, sensitivity to 5.0 micrograms/mL, recovery of 90 to 100%, and precision reflected by a SD +/- 0.90 microgram/dL. Lack interference is documented for 6 commonly prescribed anti-epileptic drugs and 4 drugs with similar retention times on this stationary phase; only guaifenesin was found to potentially interfere with the determination of methsuximide. We conclude that the method reported here is ideally suited for monitoring therapeutic and toxic levels of this anti-epileptic drug.
Chromatography, Gas↗
Measurement of antidepressants using solid-phase extraction and wide-bore capillary gas chromatography with nitrogen-selective detection.
A comprehensive method is presented for the determination of nine antidepressant drugs and metabolites in serum: (1) amitriptyline, (2) nortriptyline, (3) imipramine, (4) desipramine, (5) maprotiline, (6) doxepin, (7) desmethyldoxepin, (8) protriptyline, and (9) trimipramine. Chlorimipramine is used as the internal standard. A simple solid-phase extraction procedure utilizing disposable reversed-phase C18 columns is described. Samples are analyzed by gas chromatography with nitrogen-selective detection using a wide-bore capillary column with a permanently bonded, non-polar stationary phase. The assay possesses linearity to 800 ng/mL for maprotiline and 500 ng/mL for the other antidepressants, sensitivity to at least 25 ng/mL, recovery ranging from 96 to 107%, and between-run precision reflected by CVs of 4.4 to 8.1%. Lack of interference is documented for over 27 commonly prescribed drugs. We conclude that the method reported here is ideally suited for monitoring therapeutic and toxic levels of antidepressant drugs.
Antidepressive Agents↗
Effects of long-term haemodialysis on lipid, lipoprotein and apolipoprotein levels of black patients with chronic renal failure.
Premature coronary artery disease is believed to be a major cause of death in patients undergoing long-term haemodialysis. We investigated the effects of chronic maintenance haemodialysis on lipid, lipoprotein and apolipoprotein levels of 42 black patients with chronic renal failure and compared them with those of 40 age- and sex-matched black controls to determine the changes in the lipoprotein profile and their possible contributions to increased risk of coronary heart disease in these patients. There were increases in triglyceride levels and in total/high density lipoprotein cholesterol ratios and decreases in high density lipoprotein cholesterol, in LDL cholesterol, in apolipoprotein AI and in apolipoprotein AII in haemodialysis patients in comparison to controls. No significant differences were observed in any of the lipid, lipoprotein and apolipoprotein levels between male and female patients and between patients receiving anti-hypertensive therapy and those who were not. Our findings suggest that haemodialysis and/or events associated with maintenance dialysis may contribute to unfavourable variations in lipoprotein metabolism and, in turn, the increased mortality from coronary artery disease in this patient population.
Apolipoproteins↗