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Biomedical subjects

L M Silverman

Publications and source records attributed to L M Silverman.

At least 55 records · Page 3Linked to original sources
PubMed1989

Characteristics of creatine kinase-MB and MB isoforms in serum after reperfusion in acute myocardial infarction.

Characteristics of CK-MB, the MB1 and MB2 isoforms, and the MB2/MB1 ratio are described in six acute myocardial infarction (AMI) patients in whom the infarct-related artery was identified and, after intervention, normal coronary flow was re-established. After myocardial reperfusion, washout of CK-MB and the MB2 isoform occurred in parallel, with CK-MB peaking between 5.75 and 10.0 h, and MB2 peaking between 4.50 and 8.00 h. In five of the six patients, MB1 peaked between 8.75 and 15.5 h; the MB2/MB1 ratio demonstrated the earliest peak from 0.75 to 2.25 h. When we compared this study group to an additional 10 AMI patients who had achieved myocardial reperfusion earlier, we found a significant difference (P less than 0.005) for all tests, except MB1 isoform activity, as early as 50 min after reperfusion. This same comparison, by logistic-regression analysis, showed that the MB2/MB1 ratio discriminated between the groups 50 min after reperfusion (P less than 0.05); MB2 showed near-significance at 100 min (P less than 0.057); and CK-MB achieved significance after 200 min (P less than 0.05). CK-MB, the MB2 isoform, and especially the MB2/MB1 ratio show potential for the early, noninvasive detection of myocardial reperfusion.

Aged↗
PubMed1988

Immunoturbidimetric measurement of serum retinol-binding protein in renal and hepatic disease.

Serum retinol-binding protein (RBP), with a biological half-life of less than 12 h, is a useful indicator of liver or kidney dysfunction. An automated immunoturbidimetric assay for the measurement of RBP has been developed using the Cobas-BIO centrifugal analyser and commercially available materials. Serum samples with RBP concentrations as low as 3 mg/L were measured. Within-run and day-to-day imprecision were 3.7 and 5.7%, respectively. The reference range (mean +/- 2SD) for 51 adults was 17 to 61 mg/L. Slight haemolysis of serum (haemoglobin 10 g/L) resulted in an apparent 8% reduction of RBP with greater interference at higher haemoglobin concentrations. However, bilirubin in concentrations up to 0.15 g/L did not interfere with RBP measurements. There was good correlation between immunoturbidimetry and a commercial radial immunodiffusion method. Serum RBP concentrations were decreased in liver disease and increased in renal failure.

Humans↗
PubMed1987

A simple immunotechnique for the determination of serum concentration of apolipoprotein E.

Immunoturbidimetric assay for the determination of serum apolipoprotein E was developed on the Cobas-BIO centrifugal analyzer using commercially available antisera and reference sera. Within-run imprecision was 2.9% while day-to-day imprecision was 7.9%. Addition of up to 50 g/l hemoglobin or 0.15 g/l bilirubin to sera did not interfere with the determination of this apolipoprotein. Apolipoprotein E concentration was measured in sera from 40 normolipidemic and hyperlipidemic subjects by this immunoturbidimetric method (dependent variable) and radial immunodiffusion assay (independent variable). A slope of 0.90, an intercept of -7.9, and a correlation coefficient of 0.94 were obtained. Reference range for apolipoprotein E was established using sera from 100 normolipidemic subjects. The mean + 1 SD for apolipoprotein E levels of males and females were 36 + 13 mg/l and 29 + 8.4 mg/l, respectively. The distribution of apolipoprotein E among the various lipoprotein fractions of normals was significantly different than that of hypertriglyceridemic subjects.

Adolescent↗
PubMed1987

Immunoturbidimetry: an attractive technique for the determination of urinary albumin and transferrin.

Immunoturbidimetry is a suitable technique for the determination of urinary proteins in clinical laboratories. We have developed immunoturbidimetric assays for the measurement of urinary albumin and transferrin which are adapted for the Cobas-BIO centrifugal analyzer. Linear range for the albumin assay was 6.25-167 mg/L and for the transferrin assay 1.66-6.66 mg/L. The analytical recoveries of albumin and transferrin averaged 96%. The addition of up to 50 g/L hemoglobin to urine did not interfere with the determination of either protein. Within-run and between-run imprecision for albumin assay was 2.2% and 3.2% at an albumin level of 140 mg/L, and 4.8% and 8.7% at an albumin level of 16 mg/L; for transferrin assay the respective imprecisions were 3.6% and 6.7% at transferrin concentration of 6 mg/L, and 5.2% and 11.1% at a transferrin concentration of 1.5 mg/L. Reference ranges for both assays were established using urines from 17 healthy individuals; albumin had a range of 0-22 mg/L and transferrin 0-1.9 mg/L.

Albuminuria↗
PubMed1987

Clinical applications of DNA probes in the diagnosis of genetic diseases.

Currently, advances in molecular technology involving recombinant DNA have led to dramatic breakthroughs in genetic diseases, cancer research, and identification of foreign DNA. Of particular interest is the impact these tools have made and will make on the clinical laboratory. We describe the techniques and their effects on clinical testing in the chemistry laboratory by using selected examples of available applications. Specific examples include carrier detections and prenatal diagnosis in cystic fibrosis and hemophilia, and sickle cell anemia.

Anemia, Sickle Cell↗
PubMed1987

Population genetics of coagulant factor IX: frequencies of two DNA polymorphisms in five ethnic groups.

Two frequently used restriction-enzyme polymorphisms (RFLPs) of coagulant F.IX, TaqI and XmnI, have been examined in five ethnic groups: white Americans, black Americans, East Indians, Chinese, and Malays. There is a distinct "cline" in the frequencies of both polymorphisms, from white Americans to Malays. The rarer type 2 alleles of both polymorphisms, in which middle recognition sites are present--and which in our sample reach their highest frequencies in white Americans--are marginally higher in four groups of Europeans previously reported by others. The frequencies of the rarer alleles are significantly higher in Europeans than in black Americans and East Indians, and these alleles are essentially absent in Chinese and Malays. The frequency of heterozygosity diminishes in the same order, being zero in Malays for both polymorphisms. The polymorphisms are in strong linkage disequilibrium, and in all groups the type 1 allele for TaqI is disproportionately accompanied by the type 1 allele for XmnI. The paucity of type 2 alleles and the low rate of heterozygosity in four non-European groups suggest that the polymorphisms will be of little diagnostic value south of Gibraltar and east of Suez. This prediction is confirmed by the observed haplotype frequencies in the black American and the Oriental groups.

Alleles↗
PubMed1987

Changes in cerebrospinal fluid IgG and apolipoprotein E indices in patients with multiple sclerosis during demyelination and remyelination.

Approximately 85% of patients with multiple sclerosis (MS) can be diagnosed by using magnetic resonance imaging and laboratory tests such as determination of the cerebrospinal fluid (CSF) IgG Index and electrophoresis to detect oligoclonal banding. However, these tests results are abnormal in MS patients whether they are in clinical remission or acute exacerbation. Because apolipoprotein E (apo E) is synthesized in the central and peripheral nervous system, particularly during remyelination, we propose that apo E might be a reliable marker of the remyelination that accompanies clinical remission in MS patients. We studied 33 patients with MS, 22 in remission and 11 in exacerbation, and 26 controls of comparable ages. The apo E Index, calculated from the concentrations of apo E and albumin in CSF and serum, allowed us to discriminate between MS patients in remission and MS patients in exacerbation (P less than 0.001); the IgG Index failed to show similar differences. However, combining the apo E and IgG indices gave maximum discrimination between controls, MS patients in remission, and those in exacerbation. This study suggests that apo E measurements should be included in the laboratory evaluation of MS patients.

Adult↗
PubMed1986

A preliminary study of urinary transferrin as a marker for prostatic cancer.

Traditional serum markers used in the diagnosis of prostate cancer lack sensitivity and specificity. Prostatic fluid is in direct contact with the prostate epithelium and, thus, has been investigated as a better source for potentially useful markers. Since prostatic fluid contents can enter the urine directly through the urethra, without prerequisite entry into blood, proteins present in significant quantities in prostatic fluid represent candidate markers for entry into the urine, particularly in diseases affecting the prostate epithelium, such as adenocarcinoma. High concentrations of transferrin in prostatic fluid led us to examine urine transferrin levels, using an immunoturbidimetric technique. Urine transferrin was significantly increased in 18 out of 22 patients with prostate cancer in comparison to age-matched controls. Since there was no evidence of increased transferrin excretion, we suggest that prostatic fluid is the source of transferrinuria.

Aged↗
PubMed1986

Immunoturbidimetric techniques for quantifying apolipoproteins CII and CIII.

Immunoturbidimetric assays for determination of serum apolipoproteins CII and CIII (apo CII and CIII) were developed for use on the Cobas-Bio centrifugal analyzer with commercially available antisera and reference sera. Within-run and between-run imprecision (CVs) for apo CII was respectively 3.3 and 6.2%, and for apo CIII 2.75 and 5.2%. Addition to sera of as much as 50 g of hemoglobin or 0.15 g of bilirubin per liter did not interfere with determinations of apolipoproteins. Concentrations of apo CII and CIII were measured in sera from 40 normolipidemic and hyperlipidemic subjects by these immunoturbidimetric methods (x) and by radial immunodiffusion assays (y). Apo CII and CIII gave slopes of 0.93 and 0.86, y-intercepts of 7.4 and 9.5 mg/L, and correlation coefficients of 0.96 and 0.94, respectively. Reference intervals for the two apolipoproteins were established with sera from 100 normolipidemic subjects. The distribution of apo CII and CIII among the various lipoprotein fractions for normal subjects differed significantly (p less than 0.005) from that for hypertriglyceridemic subjects.

Apolipoprotein C-II↗
PubMed1985

Normal results of post-race thallium-201 myocardial perfusion imaging in marathon runners with elevated serum MB creatine kinase levels.

Elevated cardiac enzyme values in asymptomatic marathon runners after competition can arise from skeletal muscle through exertional rhabdomyolysis, silent injury to the myocardium, or a combined tissue source. Peak post-race levels of the MB isoenzyme of creatine kinase are similar to values in patients with acute myocardial infarction. Previously reported normal results of infarct-avid myocardial scintigraphy with technetium 99m pyrophosphate in runners after competition suggest a non-cardiac source but cannot exclude silent injury to the myocardium. Therefore, thallium 201 myocardial perfusion imaging was performed in runners immediately after competition together with determination of sequential cardiac enzyme levels. Among 15 runners tested, the average peak in serum MB creatine kinase 24 hours after the race was 128 IU/liter with a cumulative MB creatine kinase release of 117 IU/liter; these values are comparable to those in patients with acute transmural myocardial infarction. Thallium 201 myocardial scintigraphic results were normal in five runners randomly selected from those who volunteered for determination of sequential blood levels. Serum lactate dehydrogenase isoenzymes showed only a peripheral pattern of release. It is concluded that elevations of serum MB creatine kinase in marathon runners arise from a skeletal muscle source and that thallium 201 myocardial scintigraphy is useful to assess runners for myocardial injury when clinical questions arise.

Creatine Kinase↗
PubMed1985

Oligoclonal banding in cerebrospinal fluid assessed by electrophoresis on agarose after centrifugal sample concentration through a microconcentrator membrane.

We describe use of a microconcentrator membrane with a 30 000-Da cutoff for treatment of cerebrospinal fluid (CSF) specimens before detection of oligoclonal bands by electrophoresis on agarose. After centrifugation at 2000 X g for 25 min, 0.5-, 1.0-, and 2.0-mL aliquots of CSF were concentrated 15-, 25-, and 40-fold. Analytical recovery of immunoglobulins G and A from the microconcentrators was about 90% (CV 5-8%). We found good correlation between results by this method and by a silver-stain procedure in a study comparing oligoclonal banding in CSF from multiple sclerosis and control patients. After 40-fold concentration of 2 mL of CSF, 2 mg of immunoglobulin G per liter can be detected, because the analytical sensitivity of the electrophoresis is 80 mg/L.

Centrifugation↗
PubMed1985

Adenylate kinase: an oncodevelopmental marker in an animal model for human prostatic cancer.

Data are presented demonstrating that adenylate kinase (AK; EC 2.7.4.3) is an oncodevelopmental enzyme in the prostate of Copenhagen rats. We selected the Dunning tumor (dorsal rat prostate) as a model system because it most nearly approximates the human pathology. Four sublines of the tumor (R3327-H, R3327-AT, MAT Lu, and MAT LyLu) were studied. The tumor sublines were maintained as solid tumors in syngeneic rats and as monolayers in tissue culture. AK activity appeared in conjunction with malignant transformation of the dorsal prostate. We also determined the normal developmental enzyme pattern: AK was present in prostates of newborns, but was undetectable in prostates of adults. However, AK increased after castration. Therefore, we propose AK as a potential oncofetal tumor marker in prostatic cancer.

Adenocarcinoma↗