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H C Robinson

Publications and source records attributed to H C Robinson.

At least 37 records · Page 2Linked to original sources
PubMed1991

Oncofetal expression of the human intestinal mucin glycoprotein antigens in gastrointestinal epithelium defined by monoclonal antibodies.

A mucin preparation from a colonic adenocarcinoma was used to prepare monoclonal antibodies (MAbs) that reacted specifically either with normal adult small-intestine mucin antigen(s) (SIMA), or normal adult large-intestine mucin antigen(s) (LIMA). Both SIMA and LIMA show a unique oncofetal pattern of expression. Thus SIMA was expressed in early fetal stomach, large and small intestines but thereafter only in the normal small intestine. SIMA expression was detected immunohistochemically in cancers of the colorectum (82/112) and stomach (48/86). LIMA was detected in the stomach of the early fetus but thereafter only in the normal large intestine. LIMA expression was detected in 61/86 cancers of the stomach. Moreover, both SIMA and LIMA were expressed inappropriately in mucosa adjacent to tumors, indicative of the detection of possible pre-malignant epithelium. We used a sandwich ELISA and biochemical procedures to show that the SIMA and LIMA molecules were large extensively glycosylated multi-unit mucin glycoproteins that differed markedly from each other. SIMA, whether extracted from normal small-intestine or colonic cancers, had a molecular weight above 1.000 kDa, a mean buoyant density 1.33 g/ml and s value of 4.8. LIMA had a molecular weight above 10.000 kDa, a mean buoyant density 1.45 g/ml and an s value 9.5. The SIMA and LIMA epitopes were judged to be carbohydrate in nature by reason of their resistance to harsh physical chemical treatments or protease digestion, and sensitivity to periodate oxidation, neuraminidase or beta elimination. Only the SIMA epitope was sensitive to neuraminidase. In conclusion, MAbs to carbohydrate-dependent epitopes on SIMA and LIMA identify the oncofetal pattern of expression of these distinct intestinal mucin glycoproteins in colonic and gastric carcinoma. These MAbs will be useful in further studies of the significance of oncofetal mucin expression during carcinogenesis.

Adenocarcinoma, Mucinous↗
PubMed1991

Horse insurance.

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Animals↗
PubMed1991

Prospective study of ambulatory monitoring and echocardiography in borderline hypertension.

This study was done to evaluate prospectively whether ambulatory blood pressure recordings (AMB) (Spacelabs) would more accurately predict increases in left ventricular mass (LVMI) than did blood pressures measured by a nurse in the absence of a physician, using a random zero sphygmomanometer (RZ) and an automated oscillometric digital device (BPI). One hundred patients being followed by their family physician with a diagnosis of borderline hypertension with at least two office diastolic readings of 90-100 mmHg were studied at baseline and every six months for two years with RZ, BPI, and AMB; echocardiography was repeated annually. Over sixty percent of the patients were normotensive in the research unit by AMB, BPI, and RZ at entry. At entry 24% of patients had increased LVMI greater than 110 g/m2 (left ventricular enlargement, LVE) and at 2 years 32% had LVE. Stepwise linear regression was used to determine which measurement was most predictive of LVE at two years. It showed that the most predictive were baseline echo LVMI and BPI systolic pressure. These two variables predicted 45% of the risk with no other variables contributing significantly. However, when BPI was removed, AMB systolic pressure contributed significantly, though the strength of prediction was reduced to 40%. In a subset of 40 patients who underwent mental stress with mental arithmetic and mirror tracing, the magnitude of systolic pressure elevation during mental stress correlated significantly with LVE over 2 years (R = 0.54, p less than 0.001).

Adolescent↗
PubMed1990

The mechanism of initiation of chondroitin sulphate synthesis by beta-D-galactosides.

Embryonic chicken cartilage was incubated in vitro with phenyl-beta-[6-3H]galactoside and cycloheximide. Free chondroitin sulphate chains initiated by galactoside were isolated and degraded to yield 3-O-beta-D-glucuronosyl D-galactose (GlcA-Gal) derived from the sequence, GlcA-Gal-Gal-Xyl-Ser, which links the polysaccharide to protein. This enabled the distribution of 3H into specific galactose residues within the linkage oligosaccharide to be determined. Most of the 3H label (65%) was released as free galactose although 35% was recovered as GlcA-Gal. Similar experiments performed with unlabelled phenyl-beta-galactoside and [14C]galactose yielded 14C-labelled GlcA-Gal as a major product. We conclude that beta-galactosides initiate chondroitin sulphate synthesis primarily by serving as substrates for galactosyl transferase II.

Animals↗
PubMed1990

The N-terminal sequence of the large proteoglycan of articular cartilage.

A peptide with hyaluronic acid-binding properties was isolated from trypsin digests of bovine articular cartilage proteoglycan aggregate. This peptide originated from the N-terminus of the proteoglycan core protein, retained its function of forming complexes with hyaluronate and link protein and contained at least one keratan sulfate chain. Amino acid sequence data demonstrated that the first six amino acid residues of the N-terminus of bovine articular cartilage proteoglycan core protein differed from the same region from the rat chondrosarcoma proteoglycan. Further sequence data indicate areas of considerable sequence homology in the hyaluronic acid-binding regions of proteoglycans from the two species.

Amino Acid Sequence↗
PubMed1989

Synthesis of hyaluronate in cultured bovine articular cartilage.

The synthesis and distribution of hyaluronate and proteoglycan were studied in bovine articular cartilage in short-term explant culture with [3H]acetate and H2(35)SO4 as precursors. The incorporation of [3H]acetate into hyaluronate and sulphated glycosaminoglycans was linear with time, except that hyaluronate synthesis showed a marked lag at the beginning of the incubation. [3H]Hyaluronate represented 4-7% of the total [3H]glycosaminoglycans synthesized over a 6 h period. However, the distributions of [3H]hyaluronate and 3H-labelled sulphated glycosaminoglycans were different: about 50% of the newly synthesized [3H]hyaluronate appeared in the medium, compared with less than 5% of the 3H-labelled sulphated proteoglycans. A pulse-chase experiment revealed that the release of newly synthesized [3H]hyaluronate from cartilage was rapid. No difference was observed in the distribution of [3H]hyaluronate between medium and tissue by cartilage from either the superficial layer or the deep layer of articular cartilage. When articular cartilage was incubated with 0.4 mM-cycloheximide, proteoglycan synthesis was markedly inhibited, whereas the synthesis of hyaluronate was only partially inhibited and resulted in more of the newly synthesized hyaluronate being released into the medium. Analysis of the hydrodynamic size of [3H]hyaluronate isolated from cartilage on Sephacryl-1000 revealed one population that was eluted as a broad peak (Kav. less than 0.7), compared with two populations (Kav. greater than 0.5 and less than 0.5) appearing in the medium of cultures. These data suggest that hyaluronate is synthesized in excess of proteoglycan synthesis and that the hyaluronate that is not complexed with proteoglycans is rapidly lost from the tissue.

Animals↗
PubMed1986

Control of proteoglycan biosynthesis. Further studies on the effect of serum on cultured bovine articular cartilage.

Proteoglycan synthesis in explant cultures of adult bovine articular cartilage is stimulated in a dose-dependent manner when the tissue is cultured in the presence of foetal-calf serum. The stimulation of proteoglycan synthesis is paralleled by a similar increase in DNA synthesis; however, when DNA synthesis is inhibited by hydroxyurea the stimulation of proteoglycan synthesis by serum remains essentially the same. The apparent half-life of the pool of proteoglycan core protein precursor was measured in freshly isolated tissue as well as in tissue cultured for 7 days in the presence and in the absence of foetal-calf serum; under all conditions the half-life was the same, suggesting that this value is independent of the net rate of proteoglycan synthesis. In the presence of actinomycin D, an inhibitor of RNA synthesis, there was a difference in the apparent half-life of the available pool of mRNA coding for proteoglycan core protein: 8.5 h for tissue maintained in the presence of serum and 3.8 h for tissue cultured in the absence of serum. It is suggested that proteoglycan synthesis is stimulated by serum factors at the level of DNA-dependent RNA synthesis. Concomitant with an increase in the rate of proteoglycan synthesis induced by the presence of serum in the culture medium, an increase in the concentrations of several glycosyltransferases involved in chondroitin sulphate synthesis was also observed.

Animals↗
PubMed1986

The relation of RNA synthesis to chondroitin sulphate biosynthesis in cultured bovine cartilage.

Addition of actinomycin D (or cordycepin, an alternative inhibitor of RNA synthesis) to cartilage cultures resulted in a first-order decrease in the rate of incorporation of [35S]sulphate into proteoglycan (half-life = 7.5 +/- 1.1 h). Addition of 1.0 mM-benzyl beta-D-xyloside relieved the initial inhibition of glycosaminoglycan synthesis induced by actinomycin D; however, after a lag of about 10 h the rate of xyloside-initiated glycosaminoglycan synthesis also decreased with apparent first-order kinetics (half-life = 7.1 +/- 1.8 h), which paralleled the decrease in the rate of core-protein-initiated glycosaminoglycan synthesis. The hydrodynamic size of the proteoglycans formed in the presence of actinomycin D remained essentially constant (Kav. 0.21-0.23), whereas the constituent glycosaminoglycan chains were larger than those formed by control cultures, which suggested that the core protein was substituted with fewer but larger glycosaminoglycan chains. Proteoglycans formed in the presence of beta-D-xyloside were significantly smaller (Kav. approximately 0.33) than those synthesized by control cultures, and were further diminished in size after exposure of cultures to actinomycin D. Glycosaminoglycan chains synthesized by these same cultures on to both core-protein and xyloside acceptors were also smaller than those of control cultures. The decrease in synthesis observed after exposure to actinomycin D was not reflected by any significant decrease in the activities of several glycosyltransferases involved in chondroitin sulphate synthesis (galactosyltransferase-I, galactosyltransferase-II, N-acetylgalactosaminyltransferase and glucuronosyltransferase-II).

Animals↗
PubMed1986

The physician's actions and the outcome of illness in family practice.

The outcome of new episodes of common nonrespiratory tract symptoms was studied in 193 patients attending family physicians. After controlling for demographic, psychological, and social variables, the only element of the process of care that was related to resolution of the patient's symptom at one month was physician-patient agreement about the nature of the problem. Patients with unresolved symptoms were followed for an additional two months. Late resolution was associated with the physician's recording of attention to psychosocial problems. These results have implications both for the provision and audit of primary care.

Adolescent↗
PubMed1985

Initiation of chondroitin sulphate synthesis by beta-D-galactosides. Substrates for galactosyltransferase II.

beta-Galactosides were found to initiate chondroitin sulphate chain synthesis in chick-embryo cartilage in vitro and thereby relieve inhibition by cycloheximide of [3H]-acetate incorporation into chondroitin sulphate. beta-Galactosides with an apolar aglycan group such as phenyl O-beta-galactoside were active, whereas those with a charged or polar aglycan group such as pyridine 3-O-beta-galactoside or those with sulphur instead of oxygen in the glycosidic linkage (phenyl beta-thiogalactoside) were not. beta-Galactosides also serve as substrates for microsomal galactosyltransferase activity from chick-embryo cartilage. Phenyl O-beta-galactoside and pyridine 3-O-beta-galactoside were effective substrates for this enzyme, but phenyl S-beta-thiogalactoside and pyridine 2-S-beta-thiogalactoside were only slightly active. This galactosyltransferase was shown to be a separate enzyme from galactosyltransferase I, which catalyses transfer of galactose from UDP-galactose to beta-xylosides. It is proposed that the enzyme catalysing this reaction is galactosyltransferase II, responsible for transfer of the second galactose residue of the chondroitin sulphate linkage oligosaccharide. No transfer of glucuronic acid from UDP-glucuronic acid to beta-galactosides, catalysed by the microsomal preparation could be detected.

Animals↗
PubMed1984

The relation of protein synthesis to chondroitin sulphate biosynthesis in cultured bovine cartilage.

The effect of cycloheximide on chondroitin sulphate biosynthesis was studied in bovine articular cartilage maintained in culture. Addition of 0.4 mM-cycloheximide to the culture medium was followed, over the next 4h, by a first-order decrease in the rate of incorporation of [35S]sulphate into glycosaminoglycan (half-life, t 1/2 = 32 min), which is consistent with the depletion of a pool of proteoglycan core protein. Addition of 1.0 mM-benzyl beta-D-xyloside increased the rate of incorporation of [35S]sulphate and [3H]acetate into glycosaminoglycan, but this elevated rate was also diminished by cycloheximide. It was concluded that cycloheximide exerted two effects on the tissue; not only did it inhibit the synthesis of the core protein, but it also lowered the tissue's capacity for chondroitin sulphate chain synthesis. Similar results were obtained with chick chondrocytes grown in high-density cultures. Although the exact mechanism of this secondary effect of cycloheximide is not known, it was shown that there was no detectable change in cellular ATP concentration or in the amount of three glycosyltransferases (galactosyltransferase-I, N-acetylgalactosaminyltransferase and glucuronosyltransferase-II) involved in chondroitin sulphate chain synthesis. The sizes of the glycosaminoglycan chains formed in the presence of cycloheximide were larger than those formed in control cultures, whereas those synthesized in the presence of benzyl beta-D-xyloside were consistently smaller, irrespective of the presence of cycloheximide. These results suggest that beta-D-xylosides must be used with caution to study chondroitin sulphate biosynthesis as an event entirely independent of proteoglycan core-protein synthesis, and they also indicate a possible involvement of the core protein in the activation of the enzymes of chondroitin sulphate synthesis.

Acetates↗
PubMed1984

The structure of the linkage region of bovine nasal cartilage proteoglycan after beta-elimination and sulfite addition.

A method of peptide "fingerprinting" has been developed allowing the separation of the majority of the tryptic peptides of purified proteoglycan subunit from bovine nasal cartilage. When this preparation was reacted with 0.2 M sodium sulfite at pH 11.5, beta-elimination of the substituted glycosaminoglycans and O-linked oligosaccharides and the quantitative addition of sulfite occurred in the serine and threonine residues of the linkage region. After elimination-addition studies with sodium [35S] sulfite, 6 radiolabelled linkage peptides were isolated by 2-dimensional "fingerprinting." Five of these peptides were derived from a section of the protein core in which each [35S] cysteic acid residue was separated by an average of 6-10 amino acid residues. Apart from [35S] cysteic acid, the predominant amino acids in the attached peptides were glycine and glutamic acid (or glutamine), suggesting that a combination of these amino acids in the nascent protein core may be important for the initiation of glycosaminoglycan chains during proteoglycan biosynthesis.

Animals↗
PubMed1984

The effect of benzyl beta-D-xyloside on keratan sulphate synthesis in ox articular cartilage.

Cartilage from adult bovine hock joints was incubated with [3H]galactose or [35S]sulphate in the presence of benzyl beta-D-xyloside. Radioisotope incorporation into proteoglycan was inhibited by the xyloside; the magnitude of this inhibition depended on the concentration of xyloside used. With 0.2mM xyloside radioisotope incorporation into keratan sulphate was not altered but inhibition was observed at xyloside concentrations of 1.0mM or higher. The decrease in radioisotope incorporation into keratan sulphate in the presence of 1.0mM benzyl beta-xyloside was directly related to a reduction in the average length of the keratan sulphate chains. This effect of beta-xyloside on keratan sulphate biosynthesis was markedly different from its effect on chondroitin sulphate biosynthesis.

Animals↗
PubMed1983

The effect of serum on biosynthesis of proteoglycans by bovine articular cartilage in culture.

Proteoglycan synthesis by slices of adult bovine articular cartilage is stimulated two-to threefold when tissue is cultured in the presence of fetal calf serum for 5-6 days. After this, essentially steady-state conditions are achieved for up to 14 days in which the high synthetic rates are maintained and the amount of proteoglycan in the tissue remains nearly constant. In the absence of fetal calf serum, synthesis declines to a lower level and there is a gradual, net loss of proteoglycan from the tissue. Tissue maintained without serum for several days rapidly increases synthetic rates to the higher levels over 2-3 days after transferring into medium with serum, and vice versa, indicating that the response of the chondrocytes to serum factors is reversible. The structures of the proteoglycans synthesized under all medium conditions were typical for cartilage. Only small differences in glycosaminoglycan chain sizes and a consistent decrease in the relative amount of keratan sulfate to chondroitin sulfate during the first days in the culture were observed. The net capacity of the cells for chondroitin sulfate synthesis, as estimated by incubation in the presence of exogenous beta-xyloside acceptor, increased (or decreased) in parallel with the changes in endogenous proteoglycan synthesis when cultures were transferred from medium without to medium with serum (or vice versa), suggesting that changes in the net amounts of the enzymes for chondroitin sulfate synthesis are closely coordinated with changes in the amount of core protein being processed to proteoglycans. The responses of calf articular cartilage in the same system were somewhat different. Serum in the medium was required to maintain initial high levels of synthesis. The proteoglycans synthesized contained a lower proportion of keratan sulfate than those initially synthesized in the adult tissue, and there was no change in this proportion with time in culture. The maintenance of steady-state conditions for proteoglycan metabolism by either adult or calf tissue in the presence of serum in these cultures should provide a useful model for studying the regulation of synthesis and catabolism of proteoglycans by chondrocytes residing in a nearly normal extracellular matrix for long periods of time.

Animals↗
PubMed1982

Enzymatic depolymerization of heparin-related polysaccharides. Substrate specificities of mouse mastocytoma and human platelet endo-beta-D-glucuronidases.

Two endo-beta-D-glucuronidases acting on heparin-related polysaccharides were investigated: a mouse mastocytoma enzyme previously implicated in the postbiosynthetic modification of the heparin proteoglycan and a human platelet-derived enzyme, capable of degrading heparan sulfate as well as heparin (with elimination of anticoagulant activity). The mastocytoma enzyme was found to depolymerize a heparin precursor polysaccharide containing both N- and O-sulfate groups to fragments somewhat smaller in molecular size than commercially available heparin. In contrast, another heparin precursor species, containing N- but no O-sulfate groups was resistant to degradation. Furthermore, incubation of the mastocytoma endoglucuronidase with a heparin octasaccharide having high affinity for antithrombin failed to cleave the beta-glucuronidic linkage in the antithrombin-binding region. Previous studies established that the platelet endoglucuronidase can degrade the exclusively N-sulfated as well as the N- and O-sulfated heparin precursor polysaccharides (Oldberg, A., Heldin, C.-H., Wasteson, A., Busch, C., and Höök, M. (1980) Biochemistry 19, 5755-5762). This enzyme has now been found to attack also the beta-glucuronidic linkage in the antithrombin-binding region of the heparin molecule. The loss of bio-affinity resulting from cleavage of this linkage in the antithrombin-binding heparin octasaccharide was utilized to construct a sensitive, specific, and simple assay method for the platelet endoglucuronidase. It is concluded that the platelet endoglucuronidase has a lower degree of substrate specificity than has the mastocytoma enzyme, in reflection of the surmised functional roles of the two enzymes.

Animals↗
PubMed1981

Control of chondroitin sulphate biosynthesis. beta-D-Xylopyranosides as substrates for UDP-galactose: D-xylose transferase from embryonic-chicken cartilage.

Embryonic-chicken epiphyseal cartilage was incubated in vitro with a variety of beta-xylosides and the amount of [3H]acetate incorporation into chondroitin sulphate was determined under conditions when normal protein core production was inhibited by cycloheximide. The ability of the different beta-xylosides to relieve thea cycloheximide-mediated inhibition of chondroitin sulphate synthesis was influenced by the nature of the aglycan group of te xyloside. beta-Xylosides with apolar and uncharged aglycan groups were most effective and produced a severalfold stimulation of chondroitin sulphate biosynthesis. beta-Xylosides with charged aglycan groups were less effective initiators of chondroitin sulphate synthesis. The rate of galactose transfer from UDP-galactose to each of the beta-xylosides, catalysed by a cell-free microsomal preparation from embryonic cartilage, was measured. This study showed that the nature of the aglycan group of the beta-xyloside was a factor determining the capacity of the xyloside to act as an acceptor for galactosyltransferase I, the enzyme that catalyses the first galactose transfer reaction of chondroitin sulphate synthesis. The aglycan group of the xyloside also appeared to influence other steps leading to chondroitin sulphate chain initiation in vitro.

Acetates↗
PubMed1981

Effect of cycloheximide, beta-D-xylosides and beta-D-galactosides on heparin biosynthesis in mouse mastocytoma.

Heparin biosynthesis has been investigated with mouse mastocytoma in vitro. Minced tumour tissue catalysed the incorporation of [35S]sulphate and [3H]glucosamine into heparin and to a smaller extent into chondroitin sulphate. Addition of cycloheximide caused an inhibition (greater than 80%) of incorporation of each labelled precursor into both polysaccharides. Addition of benzyl beta-D-xyloside relieved the inhibition of incorporation into chondroitin sulphate and restored it to more than threefold that of the control incubation. The effect of beta-D-xyloside on incorporation into heparin was less marked although a consistent small increase of incorporation into this polysaccharide was observed. beta-D-Xyloside did, however, cause a marked incorporation of 35S and 3H labels into material of low molecular weight, which appeared to comprise heparin-like fragments. It is proposed that these fragments arise through a breakdown of the usual process of heparin biosynthesis.

Animals↗