Search PubMed⌕ Search

Biomedical subjects

A M Green

Publications and source records attributed to A M Green.

At least 37 records · Page 2Linked to original sources
PubMed1989

Characterization of the serum In(Lu)-related antigen: identification of a serum protein related to erythrocyte p80.

The In(Lu) gene has been shown previously to downregulate expression by erythrocytes and by a subset of leukocytes of an 80-Kd protein antigen defined by monoclonal antibody (MoAb) A3D8. A3D8 antibody has also been shown by inhibition studies to recognize a serum antigen; this serum antigen is present in reduced amount in serum from In(Lu) donors. The present study demonstrates that the serum antigen recognized by A3D8 antibody also resides on a protein similar in size to the protein present in erythrocyte membranes. Studies using chromatographically purified protein have further shown that this antigen shares many epitopes with that present in RBCs and is therefore likely to be extremely homologous or identical to the erythrocyte In(Lu)-related p80.

Animals↗
PubMed1988

Identification of human erythrocyte blood group antigens on decay-accelerating factor (DAF) and an erythrocyte phenotype negative for DAF.

Decay accelerating factor (DAF) is a glycoprotein present on the surfaces of many types ofcells in contact with plasma, including erythrocytes, leukocytes, and platelets (reviewed in reference 1). A small amount of DAF is also present in serum. Numerous investigators have demonstrated that DAF inhibits the action of C3 convertases on cell surfaces, and its absence has been shown to be at least partially responsible for the abnormal sensitivity to lysis by complement exhibited by erythrocytes of patients with the acquired stem cell disorder paroxysmal nocturnal hemoglobinuria (PNH) (2). Hereditary absence of DAF has not been previously described. Tc(a) and Cr(a) are high-frequency human erythrocyte antigens . These antigens are part of a family of blood group antigens, designated Cromer related, which are all absent from the null phenotype cell IFC(-) , or Inab (3). Recently, Spring and colleagues (4) have identified two monoclonal antibodies which bound to high frequency red cell antigens absent from the Inab phenotype. They also demonstrated that these antibodies, as well as several human antisera to Cromer-related antigens, bound to a 70-kD glycoprotein when used to stain immunoblots of human erythrocyte membrane proteins . Because the wide tissue distribution of mAb reactivity, along with some of the biochemical characterization and immunoblotting data, was similar to that of DAF, we investigated whether the Cromer-related antigens Cr(a) and Tc(a) resided on the DAF molecule.

Blood Group Antigens↗
PubMed1987

Diagnosis of pericardial effusions from routine gated blood-pool imaging.

Gated blood-pool scintigraphy (GBPS) is often obtained as the initial test to evaluate symptoms suggestive of left ventricular dysfunction. Since large pericardial effusions may also cause such symptoms, the ability to recognize them on routine GBPS is of clinical importance. Characteristic features of the "halo" sign surrounding the cardiac blood pool were developed, based on the GBPS of patients with known pericardial effusions. These criteria were then applied blindly to 154 consecutive patients who underwent both GBPS and echocardiography. All five patients with large effusions (approximately greater than 500 ml) were correctly identified by GBPS (sensitivity 100%); for patients with moderate effusions (approximately 150-500 ml), the sensitivity was only 33% (3/9). There were three false positives (specificity 98%). We conclude that large pericardial effusions can be identified with high sensitivity and specificity on routine GBPS. Although echocardiography remains the method of choice for the diagnosis of effusions, inspection for characteristics suggesting their presence on GBPS should be part of routine interpretations.

Echocardiography↗
PubMed1984

Characterization of liposomes prepared using a microemulsifier.

A new type of device can prepare liposomes continuously, in large quantities and with excellent aqueous space capture efficiency. At initial lipid concentration of 300 mumol/ml these liposomes capture approx. 75% of cytosine arabinoside used as an aqueous space marker. Liposome size can be reduced by increasing the number of times the preparations are recycled through the microemulsifier. Liposomes less than 0.1 micron in diameter, as shown by electron microscopy, can be made easily. Liposomes prepared at 300 mumol/ml, composed of phosphatidylglycerol/phosphatidylcholine/cholesterol in a 0.1:0.4:0.5 molar ratio leaked less than 1% of entrapped cytosine arabinoside (Ara-C) at 4 degrees C, and less than 10% Ara-C at 37 degrees C plus serum, over a 48 h period. These liposomes could be useful for a number of applications including diagnostics, therapeutics and model membrane studies.

Biochemistry↗
PubMed1980

Nitroglycerin prophylaxis in angina pectoris. Effect of sustained release nitroglycerin capsules on anginal frequency and exercise capacity.

Since the pharmacological effects of sublingual nitroglycerin are of short duration, attempts have been made over a number of years to prolong the activity of nitroglycerin by various means, viz. : (1) topical applications of nitroglycerin ointments, relying upon percutaneous absorption; (2) changes in chemical structure leading to such derivatives as isosorbide dinitrate or pentaerythritol tetranitrate; and (3) development of pharmaceutical preparations devised to disintegrate slowly, thus releasing the active substance over a long period. The purpose of the present study was to determine the effects of such a sustained-release nitroglycerin preparation on the frequency of painful paroxysms and on exercise capacity in patients with angina pectoris. In a double-blind trial comparing the preparation with a placebo 25 patients were observed during 24 weeks. The active substance significantly reduced the number of anginal attacks and increased exercise capacity in all cases. It would therefore seem that sustained-release nitroglycerin capsules deserve to have a place in the treatment of angor pectoris. However, further studies involving a larger number of patients are required to support these conclusions.

Angina Pectoris↗
PubMed1980

The effect of radiopharmaceutical incubation time on bone scan quality.

Clinical variability in the quality of bone scans led to an evaluation of the effect of incubation time on the bone scanning agent as it affects the background quality of the scan. Results of the study suggest that an incubation time of 30 minutes produces optimal bone to soft-tissue ratios with 99mtechnetium methylene diphosphonate.

Adult↗
PubMed1974

Measurement of circulating desialylated glycoproteins and correlation with hepatocellular damage.

Addition of increasing amounts of (125)I-labeled desialylated thyroxine-binding globulin (DTBG) to hepatic cell membranes resulted in a progressive increase in binding. Saturability of membrane sites was indicated by a concentration beyond which further increases in [(125)I]DTBG resulted in no further binding. The binding curve for [(125)I]DTBG was similar to binding curves of desialylated orosomucoid, fetuin, and ceruloplasmin. An inhibition assay system using hepatic cell membranes showed that desialylated orosomucoid had a greater affinity for membrane binding sites than did DTBG but desialylated fetuin and ceruloplasmin bound less avidly than DTBG. Serum from normal persons and patients with a variety of illnesses was tested for its ability to inhibit [(125)I]DTBG binding. The inhibitory activity of 1 ml of normal serum was equivalent to that of 0.2-2 mug DTBG. Patients with Laënnec's cirrhosis, biliary cirrhosis, and hepatic metastases had greatly increased inhibitory activity in their serum. Patients with jaundice due to extrahepatic obstruction had inhibitory activity not significantly different from that found in normal serum. Column chromatography of normal serum on Sephadex G-200 resulted in inhibitory activity throughout the range of protein molecular weight. Desialylation of normal serum with neuraminidase enhanced the inhibitory activity but did not change the distribution of the activity. Gel chromatography of cirrhotic serum showed markedly increased inhibitory activity associated with the macroglobulins and the 4.5S peak and a new peak of inhibitory activity in the low molecular weight area was also seen. Inhibition of desialylated glycoprotein binding to liver cell membranes by serum from patients with hepatocellular disease raises the possibility that desialylated serum glycoproteins accumulate in the circulation and that patients with compromised hepatocellular function may no longer be able to clear them from the circulation. Alternatively, accumulation of desialylated glycoproteins in the circulation could result from defective protein synthesis by the diseased liver.

Alpha-Globulins↗
PubMed1972

Thyroxine-binding globulin: characterization of the binding site with a fluorescent dye as a probe.

The fluorescent dye 1,8-anilinonaphthalenesulfonate competed with thyroxine for binding to thyroxine-binding globulin. Fluorescence analysis indicated that the dye bound to the globulin in a molar ratio of 1:1 and with an association constant (at 23 degrees C) of 4.19 x10(6)M(-1), and that thyroxine bound to the globulin in a molar ratio of 1:1 and with an association constant (at 23 degrees C) of 2.35x10(10)M(-1). Displacement of globulin-bound dye by thyroxine was shown by fluorescence quenching, and displacement of globulin-bound thyroxine by dye was demonstrated by ultrafiltration.

Binding Sites↗
PubMed1972

Studies on human thyroxine-binding globulin. VI. The nature of slow thyroxine-binding globulin.

A model system utilizing a highly purified partially desialylated thyroxine-(T(4)) binding protein (STBG) was studied. STBG was prepared by the same affinity chromatographic method we have reported for preparation of highly purified T(4)-binding globulin (TBG). The necessary prerequisite for preparation of STBG was the use of T(4)-substituted Sepharose which had been repeatedly exposed to large volumes of serum for purification of TBG. STBG moved more slowly on cellulose acetate electrophoresis than TBG but had the same molecular weight and antigenic determinants as TBG. It bound T(4) with a 1: 1 molar ratio but its affinity for T(4) was about 10 times less than that of TB. STBG had about onefourth the sialic acid content of TBG and the electrophoretic mobility of this protein was similar to that of a T(4)-binding protein with a mobility slower than that of TBG which has been seen in the electrophoretic patterns of some normal human serums and in serums of patients with hepatic cirrhosis and which does not appear to be an artifact caused by storage and freezing of serum. This fourth slowly migrating T(4)-binding region in electrophoretograms of cirrhotic serums is completely abolished by prior incubation with rabbit antiserum to TBG. The in vitro production of partially desialylated TBG from T(4)-Sepharose which had been previously exposed to large volumes of serum may be due to adsorption of neuraminidases to the Sepharose either directly from serum or as the result of bacterial contamination. Partial desialylation of TBG in vivo may be an early step in the catabolism of this protein.

Animals↗
PubMedDate not supplied

Legal issues in human clinical investigation: a primer for physicians.

Human clinical investigation plays a central role in contemporary nuclear cardiology. It is a complex expensive endeavor triggering multiple responsibilities not otherwise encountered by physicians in clinical practice. Clinical investigators, drug and device manufacturers, hospitals and universities, governmental agencies, research subjects, patient advocacy groups, and investors all have a legitimate interest in the conduct and the outcome of clinical research. Past abuses of research subjects in many countries including those unknowingly exposed to radioactive isotopes have raised ethical concerns that are now addressed by overlapping laws, regulations, guidelines, and institutional policies that have evolved to guide the research enterprise. The policies underlying this legal and regulatory structure include protection of research subjects, protection of the integrity of research design and research data, and protection of the public and private purse. Knowledge of these laws and regulations is essential for physicians participating in clinical investigations to protect their professional and personal interests. This article reviews legal issues relevant to physicians conducting human clinical trials in the United States.

Clinical Trials as Topic↗