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Biomedical subjects

E W Bermes

Publications and source records attributed to E W Bermes.

At least 37 records · Page 2Linked to original sources
PubMed1986

The Stratus immunofluorometric assay system evaluated for quantifying human choriogonadotropin in serum.

We evaluated the Stratus (American Dade, Miami, FL), an automated immunofluorometric assay system, for the quantification of human choriogonadotropin (hCG) in serum or plasma. The assay is based on the "sandwich" (two-site) immunoassay methodology: use of two monoclonal antibodies, one specific for the alpha subunit and the other for the beta subunit, results in an assay that is specific for the intact hCG molecule. Results for the first sample are obtained in 7 min; subsequent additional values are produced at 1-min intervals. Inter-run precision (CV), estimated from replicate determinations of sera, was 4.5% at an hCG concentration of 38 int. units/L, 4.9% at 114, and 6.1% at 194. Intrarun CV was less than 2% at all three concentrations. Correlations of results for 127 specimens analyzed in duplicate with the Stratus (y) and by a radioimmunoassay (x) for beta hCG (Gamma Dab M [cf931125I] beta-hCG, Travenol-Genentech Diagnostics, Cambridge, MA) yielded the following regression equation: y = 0.969x - 6.0 (r = 0.995). The Stratus immunofluorometric system provides a rapid and convenient assay of hCG in serum or plasma.

Antibodies, Monoclonal↗
PubMed1983

A serotonin and beta HCG-producing islet cell carcinoma associated with focal nodular hyperplasia of the liver.

A 48-year-old woman is described with a pancreatic islet cell carcinoma that had no clinical evidence of hormone production. This neoplasm was removed by radical distal pancreatectomy. Immunohistochemical and extraction studies performed on the tumor tissue revealed that it was producing serotonin and beta HCG. Circulating levels of these hormones were elevated in preoperative serum samples that had been frozen. Beta HCG, a known tumor marker, has remained normal following operation, and this mirrors her clinical course since she has no evidence of disease 1.5 yr after operation. This patient also had focal nodular hyperplasia of the liver. It is possible that the trophoblastic hormone, beta HCG, which was being produced in excess by the islet tumor, may have directly or indirectly caused or facilitated the development of focal nodular hyperplasia.

Adenoma, Islet Cell↗
PubMed1983

Synthetic peptide substrates in hemostatic testing.

Since the introduction of synthetic chromogenic and fluorogenic peptide substrates from serine proteases, the testing of coagulation has undergone a dramatic conceptual and methodological change. The concept of coagulation profiling has emerged and automated methodologies are being introduced. Synthetic substrate methods for the evaluation of antithrombin-III; progressive antithrombin; plasminogen; antiplasmin; prekallikrein; antikallikrein ; alpha 1-antitrypsin; prothrombin; heparin; platelet factor IV; urokinase; tissue activator of plasminogen; factor assays; amidolytic equivalents of prothrombin time; and partial thromboplastin time have been developed. Studies on antithrombin-III indicate that immunological methods evaluate the total immunoreactive-antithrombin-III (antigenic) level and do not discriminate between functionally active forms and the AT-III serine protease complex. The clinical significance of AT-III measured by immunological methods is highly questionable. The coagulant assays for the measurement of AT-III require purified alpha-thrombin preparations. The noncoagulant forms of thrombin (beta- and gamma-) result in falsely low antithrombin-III quantitation. The molecular heterogeneity in a given thrombin preparation if standardized in terms of its amidolytic activity does not produce any errors in the quantitation of AT-III levels with synthetic peptide methods. None of the immunological methods provide clinically relevant information except in normal plasma where the immunological and functional activities are identical. Analysis of pathologic plasma samples using laser nephelometry, radial immunodiffusion and radioimmunoassay methods revealed that the functional activity of various serine protease inhibitors is greatly reduced but the reduction in the immunological quantities is minimal. Since coagulation proteins are functional, a ratio between their functional activity and absolute protein levels may be a useful parameter. Employing human and bovine thrombin; bovine and human Xa with their respective substrates, the absolute quantitation of heparin is satisfactorily carried out, however, these assays only measure heparin concentrations and do not reflect the overall anticoagulant effect of heparin. Using the synthetic substrates, the value of measuring absolute concentrations of heparin in a patient on heparin therapy is questionable. With the introduction of fluorogenic substrates, the presence of activated coagulation factors may be demonstrated in patients with thrombotic disorders.(ABSTRACT TRUNCATED AT 400 WORDS)

Anticoagulants↗
PubMed1983

Serum markers for pancreatic islet cell and intestinal carcinoid tumors: a comparison of neuron-specific enolase, beta-human chorionic gonadotropin and pancreatic polypeptide.

Neuron-specific enolase (NSE) (a glycolytic enzyme that occurs only in neuroendocrine cells), human pancreatic polypeptide (hPP) (a probable peptide hormone), and the beta-subunit of human chorionic gonadotropin (beta hCG) (a glycoprotein hormone), have been suggested as serum markers for the diagnosis and management of apudomas of the pancreas and intestinal tract. Serum levels of NSE, hPP, and beta hCG were measured in 21 patients with pancreatic islet cell cancer (including nine "nonfunctioning" tumors, six gastrinomas, three glucagonomas, two insulinomas, and one somatostatinoma) and in five patients with intestinal carcinoid tumors. Sixteen of the 26 patients (62%) had elevated circulating levels of at least one tumor marker. All three markers were elevated in only one patient, a woman with a "nonfunctioning" islet cell carcinoma. Five patients had increased levels of two serum markers. In three patients both NSE and hPP levels were above normal and in two patients both NSE and beta hCG levels were above normal. In nine patients only one marker was elevated. These included six with elevated NSE levels, two with elevated hPP levels, and one with elevated beta hCG levels. Thus NSE levels were elevated in 12, hPP levels in six, and beta hCG levels in four of the 26 patients. While no single marker was elevated in all patients, each of the three can be elevated in an individual case. When elevated, these markers may be valuable to estimate prognosis or monitor response to therapy.

Adenoma, Islet Cell↗
PubMed1983

Molecular markers of hemostatic disorders: implications in the diagnosis and therapeutic management of thrombotic and bleeding disorders.

With current technological advances, it is now possible to measure in less than 50 microL of plasma picomolar amounts of circulating products of platelet activation, products of protease activation related to coagulation and fibrinolytic pathways, and prostaglandin metabolites formed during a physiologic or pathologic process. Most of these markers, which circulate in blood in nanogram or picogram amounts per milliliter during or after pathologic activation, provide pertinent information on the status of a patient in terms of specificity and early detection, and will be of crucial value in the diagnosis of hemostatic defects and the management of newer antithrombotic drugs that cannot be monitored by currently available assays. Currently, 125I- and 3H-based simple radioimmunoassays are available for platelet factor 4, beta-thromboglobulin, fibrinopeptide A, B beta 15-42 related peptides, thromboxane B2, and the prostaglandins 6-keto-PGF1 alpha and PGE2. Nonisotopic methods such as enzyme-linked immunosorbent assays and fluoroimmunoassays are being developed. Serotonin and ADP, products of platelet activation, are measurable by liquid-chromatographic, immunoenzymatic, and spectrophotofluorometric methods. Analytical methods for fibrin split products (fragments D and E) and serine protease inhibitor complexes such as thrombin-antithrombin-III, factor Xa-antithrombin-III, and kallikrein-C1-esterase are also being developed. We have evaluated all of these methods and found them to be very sensitive to those components of endogenous activation of the hemostatic system listed above.

Blood Coagulation Disorders↗
PubMed1983

Diagnostic efficacy of newer synthetic-substrates methods for assessing coagulation variables: a critical overview.

With the introduction of synthetic substrates, many newer methods have been developed for testing coagulation parameters. Some of these methods are used in clinical settings, and many have been evaluated for their diagnostic efficacy in various coagulation disorders. Clinical chemistry laboratory instrumentation has been used to accommodate these methods. Commercially available kits for antithrombin III, heparin, plasminogen, alpha 2-antiplasmin, and factor X are used by many laboratories. Individual reagents have also become available and are being used to develop assays for routine diagnostic use. The development of suitable standards is rapidly underway, and their availability will facilitate adoption of these methods by hospital laboratories. Many of the synthetic-substrate-based assays that have been introduced for routine diagnostic purposes have been published recently. Here, we provide an overview of the newer amidolytic methods for the measurement of certain coagulation variables.

Anticoagulants↗
PubMed1981

Automation of plasma antithrombin III assays.

We have developed automated assays for antithrombin III for use with the Gilford 3500 and the Multistat Microcentrifugal Analyzer. The assays are two-stage kinetic-rate methods and involve use of human thrombin and the chromogenic peptide substrate S-2238. The reagents are prepared in-house from commercially available components. Both automated methods have good precision and results correlate well with both an established chromogenic substrate assay and an immunological assay. The automated assays offer the advantages of speed, sensitivity, high throughput, and low reagent consumption and are useful for both routine work and high-volume testing in clinical studies and screening programs.

Antithrombin III↗
PubMed1980

A comparison of enzyme immunoassay and gas chromatography/mass spectrometry in forensic toxicology.

A series of 137 urine samples were analyzed for drugs of abuse by enzyme immunoassay (EMIT) and by gas chromatography/mass spectrometry (GC/MS). Agreement between these methods was excellent and ranged from 93.4% for benzodiazepines to 98.5% for propoxyphene. EMIT false negative were traced to the presence of elevated endogenous lysozyme or other interfering materials. In the case of moderate amounts of lysozyme the use of a blank would lead to correct results. Disagreement in the identification of nine benzodiazepine samples was found to be due to a low recovery of benzodiazepine metabolites from urine. Recovery could be improved by incubation of the urine sample with the enzyme beta-glucuronidase.

Benzodiazepines↗
PubMed1980

New perspectives in coagulation testing.

The field of coagulation testing has undergone some major technological and conceptual developments, which are briefly reviewed here. The assessment of coagulation parameters is no longer restricted to the study of clot formation and its dissolution. The understanding of the biochemical nature of coagulation processes, coupled with the development of new therapeutic agents in the treatment of hemostatic disorders, has brought about the development of fast, reliable, and clearly defined laboratory test procedures to evaluate the components of this system. The introduction of methods involving synthetic substrates has been very significant because many of the coagulation parameters can now be measured with a spectrophotometer or fluorometer, by methods that lend themselves to the automation found in most large clinical chemistry laboratories. In our laboratory, we use automated synthetic-substrate methods for antithrombin-III, plasminogen, and prothrombin, and are developing the synthetic-substrate assay equivalent of clot-based prothrombin time and partial thromboplastin. Immunological methods such as laser/rate nephelometry, enzyme-linked immunoassays, electroimmunodiffusion, and radioimmunoassays have been utilized to evaluate coagulation proteins. The relation of functional and immunological properties of these proteins to their physiological function is being studied. In coming years the testing of coagulation function will undergo some major changes and will require input from clinical chemists and other laboratory scientists to facilitate the technology transfer and proper standardization of new methods.

Antithrombin III↗
PubMed1980

Radioimmunoassay of thyroxine in 10 microliters of serum, with use of aggregated antithyroxine antibodies.

We describe a sensitive radioimmunoassay for rapidly determining the concentration of thyroxine in 10 microL of human serum. Aggregated antithyroxine antibodies are used to separate bound and free hormone. This speeds the assay and economizes on reagents without loss of sensitivity, specificity, or precision. Results for normal subjects and patients with thyroid disease agree well with those obtained by other, well-established techniques.

Antibodies↗
PubMed1978

Effect of in vitro hemolysis on chemical values for serum.

Hemolysis in serum specimens is commonplace. This study examines the effect of hemolysis on results of selected chemical assays. Hemolysis was simulated by adding hemolysate to serum to give hemoglobin concentrations of 90 to 2800 mg/liter and a rating by technologists of 0 to 4 + hemolyzed. The effect of hemolysis on values for some serum constituents, particularly acid phosphatase and creatine kinase, was shown to be method dependent. Not unexpectedly, hemolysis most affects results for lactate dehydrogenase.

Acid Phosphatase↗