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Biomedical subjects

W M Becker

Publications and source records attributed to W M Becker.

At least 109 records · Page 6Linked to original sources
PubMed1981

Pancreatic oncofetal antigen in pancreatic juices. Partial chemical characterization and diagnostic application of a pancreatic cancer-associated antigen.

Antisera were raised in rabbits to an antigenic structure present in fetal pancreas tissue, pancreatic tumor tissue, and pancreatic juices and in sera obtained from pancreatic cancer patients. The first chemical data indicate that this pancreatic oncofetal antigen is distinct from CEA, NCA, and NCA2 and is not glycolipid in nature. Immunoelectrophoretic analyses demonstrate that pancreatic oncofetal antigen is a protein or a glycoprotein, which displays microheterogeneity. The apparent molecular weight of the basic unit of pancreatic oncofetal antigen is estimated to about 40 K. So far 234 pancreatic juices have been investigated for pancreatic oncofetal antigen. Pancreatic oncofetal antigen was detected within the pancreatic juices from 59 of 74 (80%) pancreatic carcinoma patients but could be traced in only 16%-26% of samples obtained from patients with other diseases.

Adult↗
PubMed1980

Regulation of Glyoxysomal Enzymes during Germination of Cucumber: 3. IN VITRO TRANSLATION AND CHARACTERIZATION OF FOUR GLYOXYSOMAL ENZYMES.

Monospecific antibodies raised against four glyoxysomal enzymes (isocitrate lyase, catalase, malate synthase, and malate dehydrogenase) have been used to detect these proteins among the products of in vitro translation in a wheat germ system programmed with cotyledonary RNA from cucumber seedlings. In vitro immunoprecipitates were compared electrophoretically with the same enzymes labeled in vivo and also with the purified proteins. Isocitrate lyase yields two bands on sodium dodecyl sulfate-polyacrylamide gels, as synthesized both in vitro (61.5K and 60K products) and in vivo (63K and 61.5K polypeptides). Both the 63K and 61.5K subunits can also be demonstrated for the isolated enzyme. The two subunits are antigenically cross-reactive and yield similar electrophoretic profiles upon partial proteolytic digestion. A larger subunit is seen in vitro than in vivo for both malate dehydrogenase (38K versus 33K) and catalase (55K versus 54K); this suggests a need for processing which is often a characteristic of proteins that must be transported across or into membranes. Malate synthase has a molecular weight of 57K both in vitro and in vivo, but the isolated enzyme is a glycoprotein, containing N-acetyl glucosamine, mannose, and possibly also fucose and xylose. This indicates that the polypeptide portion of the isolated enzyme is smaller than the in vitro product and suggests processing of malate synthase also. None of the other three enzymes appears to be glycosylated. The implications of these size differences for the compartmentalization of matrix and membrane-bound glyoxysomal enzymes are discussed.

Journal Article↗
PubMed1980

Regulation of glyoxysomal enzymes during germination of cucumber. Temporal changes in translatable mRNAs for isocitrate lyase and malate synthase.

The relative levels of translatable messenger RNA for isocitrate lyase and malate synthase were determined in the dry seed and for the first seven days of development of cucumber cotyledons. After extraction and quantification of total and poly(A)-rich RNA each day, the RNA fractions were translated in an optimized wheat germ system and the specific polypeptides were immunoprecipitated quantitatively. The radiolabeled isocitrate lyase and malate synthase polypeptides were then fractionated on dodecylsulphate/polyacrylamide gels, visualized by exposure to X-ray film and quantified densitometrically. The relative levels of translatable messenger RNA for these enzymes rise and fall with a developmental program similar to the enzyme activities, but preceding the latter by about one day. This implies that the rise in enzyme activity is dependent upon a prior postgerminative increase in translatable messenger RNA for the enzymes. These studies also suggest that messenger RNA levels may be regulated, at least in part, by light.

Glyoxylates↗
PubMed1979

[Common ALL-associated antigen on cells and in the serum of common ALL patients: clinical relevance and biochemical characterization (author's transl)].

The clinical application of an antiserum recognizing common ALL associated antigen (cALL-AG) is very useful in classifying leukemias and diagnosing bone marrow relapse as well as CNS-leukemia. We could demonstrate that sera of common ALL (cALL) patients contain cALL-AG; its partial biochemical characterization is described. The anti cALL serum (cALL-AS) was raised in rabbits with cALL-cells precoated with rabbit antiserum against normal human lymphocytes. After appropriate absorbtion the cALL-AS was highly specific for cALL cells. The isolation of serum cALL-AG was performed by ammoniumsulfat precipitation, gel chromatography and affinity chromatography on agarose lens culinaris hemagglutinin A (lentil lectin). The apparent molecular-weight of the serum glycoprotein is 125 000. Two cALL-AG active structures could be solubilized from cALL cell membrane. The apparent molecular-weights were calculated to be 55 000 and 110 000.

Antigens, Neoplasm↗
PubMed1978

Regulation of Glyoxysomal Enzymes during Germination of Cucumber: I. Developmental Changes in Cotyledonary Protein, RNA, and Enzyme Activities during Germination.

Developmental patterns of glyoxylate cycle and photosynthetic activities have been correlated with electrophoretic profiles of cotyledonary RNA and protein in both light- and dark-grown cucumber seedlings (Cucumis sativus L.) Cytoplasmic rRNA increases 10-fold between days 0 and 5, and the steepest increase coincides with the most rapid rise in activities of the glyoxysomal enzymes, isocitrate lyase and malate synthase. Chloroplast rRNA and ribulose bisphosphate (RuBP) carboxylase begin rising at day 3, followed about a day later by increases in glyoxylate reductase activity and chlorophyll content. Of these phototrophic indicators, only chlorophyll requires light for its initial appearance. Sodium dodecyl sulfate gel electrophoresis of total and soluble cotyledonary protein showed several developmental patterns, including: (a) progressive disappearance of storage protein present initially in particulate form; (b appearance and subsequent disappearance of a family of polypeptides identified by molecular weight, developmental profile, and density gradient centrifugation as subunits of glyoxysomal enzymes; and (c) appearance and progressive increase (in both light- and dark-grown cotyledons) of the large and small subunits of RuBP carboxylase, as well as other polypeptides presumably of chloroplast and peroxisomal origin.

Journal Article↗
PubMed1978

Regulation of Glyoxysomal Enzymes during Germination of Cucumber: 2. Isolation and Immunological Detection of Isocitrate Lyase and Catalase.

The glyoxysomal enzymes isocitrate lyase and catalase have been isolated from etiolated cucumber (Cucumis sativus) cotyledons. The enzymes co-purified through polyethyleneimine precipitation and (NH(4))(2)SO(4) precipitation, and were resolved by gel filtration on Sepharose 6B followed by chromatography on diethylaminoethyl-cellulose (isocitrate lyase) or hydroxylapatite (catalase). Purity of the isolated enzymes was assessed by sodium dodecyl sulfate-polyacrylamide electrophoresis, isoelectric focusing, and immunoelectrophoresis. Antibodies raised to both enzymes in rabbits and in tumor-bearing mice were shown to be monospecific by immunoelectrophoresis against total homogenate protein. Isocitrate lyase and catalase represent about 0.56% and 0.1%, respectively, of total extractable cotyledonary protein. Both enzymes appear to be present in a single form. Molecular weights of the native enzymes and its subunits are 225,000 and 54,500 for catalase, and 325,000 and 63,500 for isocitrate lyase. The pH optimum for isocitrate lyase is about 6.75 in morpholinopropane sulfonic acid buffer, but varies significantly with buffer used. The K(m) for d-isocitrate is 39 micromolar. A double antibody technique (rabbit anti-isocitrate lyase followed by (125)I-labeled goat anti-rabbit immunoglobulin G) has been used to visualize isocitrate lyase subunit protein on sodium dodecyl sulfate-polyacrylamide with high specificity and sensitivity.

Journal Article↗
PubMed1976

A polyethylene glycol/dextran procedure for the isolation of chromatin proteins (histones and nonhistones) from wheat germ.

A new procedure is described for the isolation of both histone and non-histone chromatin proteins, based on a polyethylene glycol (PEG)/dextran two-phase partition system. Chromatin is solubilized in high salt (5 M NaC1) and mixed with PEG and dextran to separate proteins (partitioned into the upper, PEG-rich phase) from nucleic acid (DNA recovered almost exclusively in the lower, dextran-rich phase). The proteins are then absorbed onto Bio-Rex 70 by dialysis to low salt (0.05 M NaC1), followed by salt elution to recover first non-histone proteins (less than 0.55 M NaC1), then histones (2 M NaC1). Cross-contamination is not detectable in either group of proteins. The procedure is rapid, gentle, and lends itself well to scale-up. The proteins are kept in pH range 7.0--8.1, and are not exposed to the denaturing reagents characteristic of most preparative procedures for chromatin proteins. Though developed specifically for the isolation of proteins from chromatin of wheat germ, the procedure should be readily applicable to other sources as well. Wheat germ (isolated wheat embryos) appears to be an excellent source of chromatin proteins; 100 g yields 225--300 mg histones and 30--45 mg nonhistone proteins, depending on technique.

Amino Acids↗
PubMed1975

Eliminating self-defeating behaviors and change in locus of control.

This study investigated changes in locus of control occurring among participants in a workshop designed to eliminate self-defeating behaviors. Experimental (n = 18) and control (n = 18) groups were composed of male and female university students. An analysis of covariance indicated that the treatment group moved significantly more than the control group (p less than .001) on the Rotter I-E Scale, and movement was in the anticipated direction, toward greater internal control. The increased internal control was maintained in a follow-up administration of the I-E Scale four months later. It was concluded that the workshop brought relatively stable changes toward greater perceived internal control. Implications were discussed.

Adaptation, Psychological↗
PubMed1974

Purification and subunit analysis of wheat-germ ribonucleic acid polymerase II.

A procedure is described for the purification of the alpha-amanitin-sensitive DNA-dependent RNA polymerase [EC 2.7.7.6] from wheat germ. Solubilization of the enzyme activity was achieved by sonication of a crude extract in a high-salt buffer. Purification involved precipitation with protamine sulphate and (NH(4))(2)SO(4), chromatography on DEAE-cellulose and phosphocellulose, and sucrose gradient centrifugation. Under denaturing conditions the enzyme dissociated into five polypeptides with molecular weights and molar ratios of 220000 (0.9), 170000 (0.1), 140000 (1.0), 45000 (0.2), and 40000 (0.4). Approx. 1mg of purified RNA polymerase was obtained as a routine from 100g of starting material.

Adenosine Triphosphate↗
PubMed1974

Cytochemical localization of malate synthase in glyoxysomes.

Cytochemical staining techniques for microbodies (peroxisomes) are limited at present to the enzymes catalase and alpha-hydroxy acid oxidase, and neither technique can distinguish glyoxysomes from other microbodies. Described here is a procedure using ferricyanide for the cytochemical demonstration by light and electron microscopy of malate synthase activity in glyoxysomes of cotyledons from fat-storing cucumber and sunflower seedlings. Malate synthase, a key enzyme of the glyoxylate cycle, catalyzes the condensation of acetyl CoA with glyoxylate to form malate and release free coenzyme A. Localization of the enzyme activity is based on the reduction by free CoA of ferricyanide to ferrocyanide, and the visualization of the latter as an insoluble, electron-opaque deposit of copper ferrocyanide (Hatchett's brown). The conditions and optimal concentrations for the cytochemical reaction mixture were determined in preliminary studies using a colorimetric assay developed to measure disappearance of ferricyanide at 420 nm. Ultrastructural observation of treated tissue reveals electron-opaque material deposited uniformly throughout the matrix portion of the glyoxysomes, with little background deposition elsewhere in the cell. The reaction product is easily visualized in plastic sections by phase microscopy without poststaining. Although the method has been applied thus far only to cotyledons of fat-storing seedlings, it is anticipated that the technique will be useful in localizing and studying glyoxylate cycle activity in a variety of tissues from both plants and animals.

Copper↗
PubMed1974

Separation and partial characterization of two ribonucleic Acid polymerases from pea seedlings.

Two DNA-dependent RNA polymerases (ribonucleoside triphosphate:RNA nucleotidyl transferase, EC 2.7.7.6) have been isolated from pea (Pisum sativum) seedlings. The enzymes were solubilized by sonication in high salt buffer and were separated by chromatography on diethylaminoethyl cellulose using a linear salt gradient. Polymerase I eluted at 0.10 m (NH(4))(2)SO(4), accounted for about 10% of the recovered activity and was completely insensitive to alpha-amanitin. Polymerase II eluted at 0.14 m (NH(4))(2)SO(4), accounted for the remaining 90% of recovered activity and was strongly inhibited by alpha-amanitin. Both enzymes preferred denatured to native DNA as template, both showed an absolute requirement of divalent cation, and both were sensitive to the ionic strength of the assay medium. The developing pea seedling seems a promising system for studies of possible changes in relative activities and roles of multiple RNA polymerases during eukaryotic development.

Journal Article↗