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Biomedical subjects

J R Clamp

Publications and source records attributed to J R Clamp.

At least 55 records · Page 3Linked to original sources
PubMed1983

The effect of bromhexine on experimentally induced diabetic nephropathy.

Diabetes was induced in male Wistar rats by a single i.v. injection of streptozotocin (40 mg/kg). Animals were treated with bromhexine at 2 dose levels (2.5 mg/kg/day and 25 mg/kg/day) for 13 months thereafter and compared to non-diabetic controls and untreated diabetic animals. Renal pathology showed a significant increase in glomerular volume and basement membrane thickening in untreated diabetic animals. The higher dose bromhexine treated diabetic animals showed a significant decrease in glomerular volume as compared with diabetic animals not given bromhexine.

Animals↗
PubMed1982

Isolation and characterization of the major oligosaccharide of human platelet membrane glycoprotein GPIb.

Treatment of intact human platelets with chymotrypsin released a glycopolypeptide that was shown to be derived from the major membrane glycoprotein, GPIb. The glycopolypeptide contained 59% carbohydrate on a molar basis and was rich in serine, threonine and proline. Almost all the carbohydrate could be released from the glycopolypeptide by treatment with alkali in the presence of NaBH4. The major component (comprising 80% of the released sugar) was purified and shown to be a hexasaccharide containing sialic acid, galactose, N-acetylglucosamine and N-acetylgalactosaminitol in the molar ratios 2:2:1:1. Two possible structures for this hexasaccharide are proposed on the basis of the known biosynthetic pathways of mucus-type glycoproteins. Our data is consistent with the occurrence of an O-glycosidically linked oligosaccharide on one amino acid in four of the glycopolypeptide. These results suggest that glycoprotein Ib can best be described as a membrane-bound mucus-type glycoproteins. Our data are consistent with the occurrence of an O- in the process by which platelets adhere to the exposed subendothelium of damaged blood-vessel walls. The possible role of the glycopolypeptide portion of GPIb in this process was investigated. Neither the major oligosaccharide nor the glycopolypeptide itself inhibited ristocetin-induced platelet agglutination at the concentrations tested. It is suggested that the carbohydrate moieties of GPIb molecules at the cell surface interact to form a barrier to macromolecules. Such a barrier could play a major role in modulating platelet function.

Amino Acids↗
PubMed1982

C-reactive protein and serum amyloid P component in the plaice (Pleuronectes platessa L.), a marine teleost, are homologous with their human counterparts.

C-reactive protein and serum amyloid P component were isolated from serum of the plaice (Pleuronectes platessa L.), a murine teleost. The isolation was based on their calcium-dependent binding affinity for pneumococcal C-polysaccharide and for agarose, respectively. These specificities are the same as those of human C-reactive protein and serum amyloid P component, respectively, and we have previously reported that the plaice molecules resemble human C-reactive protein and serum amyloid P component in their electron microscopic appearance. We describe here estimation of the molecular weights of plaice C-reactive protein and serum amyloid P component and their subunits, and analysis of their amino acid composition, glycosylation and partial amino-terminal amino acid sequences. The results establish that plaice C-reactive protein and serum amyloid P component are homologous with each other and with their human counterparts and indicate that there has been stable conservation of this protein family throughout vertebrate evolution.

Amino Acid Sequence↗
PubMed1982

Isolation and characterization of C-reactive protein and serum amyloid P component in the rat.

C-reactive protein (RP) and serum amyloid P component (SAP) have been identified for the first time in rat serum and isolated by calcium-dependent affinity chromatography. Rat CRP closely resembled human CRP in its amino acid composition, in having five subunits per molecule and in its electron microscopic appearance as a pentameric annular disc. It differed, however, from all other mammalian CRP's characterised hitherto in being a glycoprotein bearing a single complex oligosaccharide on each polypeptide subunit. Furthermore one pair of tis subunits per molecule was linked by a interchain disulphide bridges whereas in other animals the subunits of both CRP and SAP are all non-covalently associated. The serum concentration of CRP in normal healthy laboratory rats and in specific pathogen-free rats was 300-600 micrograms/ml which is much greater than has been described in any other species and exceeds even maximal acute phase levels of CRP in man. Following injections of casein or croton oil, serum CRP levels rose to a maximum of about 900 micrograms/ml. Rat CRP bound to pneumococcal C-polysaccharide (CPS( but, in marked contrast to the behaviour of CRP from man, rabbit and marine teleost fish, it did not precipitate with CPS solutions, agglutinate CPS-coated sheep erythrocytes or initiate complement activation. Rat SAP, like SAP of other species, was a glycoprotein but unlike them it was composed only of a single pentameric disc not two such discs interacting face-to-face. The normal level of SAP in rat serum was 20-50 micrograms/ml, very similar to the levels seen in man, and it did not behave as an acute phase reactant in response to casein or croton-oil injections. In this respect it resembled human SAP but differed from murine SAP which is a major acute phase reactant.

Amino Acids↗
PubMed1981

Study of the carbohydrate content of mucus glycoproteins from normal and diseased colons.

1. Mucus samples obtained from colectomy colons from 10 patients with ulcerative colitis and four patients with Crohn's disease of the colon, together with samples from 10 normal postmortem colons, have been studied. 2. Two glycoprotein fractions were isolated from mucosal scrapings by gel-permeation chromatography. The high-molecular-weight fraction consisted largely of mucus glycoproteins and was further purified to the glycopolypeptides. The low-molecular-weight fraction contained a glycoprotein with a high mannose content. The carbohydrate content of both the mucus glycoprotein and glycopolypeptide fractions were significantly reduced in active colitis. 3. Oligosaccharides were prepared from the mucus glycoprotein material. In the normal material more than half the units contained eight or more monosaccharide residues, whereas in the disease material the bulk of the units were smaller than this.

Carbohydrates↗
PubMed1979

Carbohydrate-containing materials in urine from normal and diabetic subjects.

1. Abnormalities in glycoprotein metabolism are believed to play a role in diabetic microangiopathy. We have therefore measured the urinary excretion of carbohydrate-containing materials in normal and diabetic subjects. 2. Diabetic subjects were found to excrete excessive quantities of such material, which may parallel the increases observed in plasma and structural glycoproteins found in previous studies. 3. Systemic administration of a synthetic derivative of vasicine, which is known to affect mucus glycoprotein, was shown to restore these elevated urinary concentrations seen in diabetic subjects to values close to normal, but his drug had no significant effect on urinary concentrations of such materials in normal subjects.

Carbohydrates↗
PubMed1979

Study of the oligosaccharide units from mucus glycoproteins of meconium from normal infants and from cases of cystic fibrosis with meconium ileus.

1. The mucus glycoproteins in meconium from normal infants and from infants having cystic fibrosis with meconium ileus have been studied. 2. Whereas normal meconium contained about 50% protein-bound carbohydrate, the meconium from cystic fibrosis contained only about 10%. 3. Glycopolypeptides were prepared from the mucus of glycoproteins. The oligosaccharide units from this material were released and fractionated. The fractions ranged widely in size and composition. 4. The fractions from cystic fibrosis specimens had a significantly higher content of fucose than those from normal specimens.

Carbohydrate Metabolism↗
PubMed1977

Carbohydrate content of endoscopic gastric biopsies in carcinoma of the stomach.

An investigation of the glycoproteins of gastric mucus from biopsies of patients with gastric cancer has shown a change in certain carbohydrate components. There is a significant increase (P less than 0-001) in mannose and a significant decrease in N-acetylgalactosamine in both secretors and non-secretors from cancer-free and cancer-bearing regions of the stomach as compared with normal stomachs. The possible reasons for this change and its relation to two possible glycoprotein fractions are discussed.

Acetylgalactosamine↗
PubMed1976

Abnormal carbohydrate composition of the major penetrating membrane protein of En(a-) human erythrocytes.

The major penetrating membrane glycoprotein (band 3) was isolated from En(a-) and normal human erythrocytes. The two proteins differed only in carbohydrate composition. Band 3 from En(a-) erythrocytes contained greater amounts of galactose and N-acetyl-glucosamine. The loss of the sialoglycoprotein sialotetrasaccharides in the En(a-) cell is not compensated by the appearance of these units in band 3 of En(a-) erythrocytes.

Acetylglucosamine↗
PubMed1975

The glycoprotein content of meconium.

Meconium pooled according to blood group activity has been studied. It was found to consists largely of glycoproteins. Two glycoprotein fractions have been isolated, one of which consisted of mucous-type glycoproteins and the other of "mannose-containing" glycoproteins.

ABO Blood-Group System↗
PubMed1975

Characterization by gas-liquid chromatography-mass spectrometry and proton-magnetic-resonance spectroscopy of pertrimethylsilyl methyl glycosides obtained in the methanolysis of glycoproteins and glycopeptides.

The quantitative analysis by gas chromatography of monosaccharides present in glycoproteins and glycopeptides using methanolysis, followed by re-N-acetylation and trimethylsilylation, gives rise to several peaks for each monosaccharide. The identity of these peaks for xylose, fucose, mannose, galactose, glucose, N-acetylglucosamine, N-acetylgalactosamine and N-acetylneuraminic acid was established for alpha- and beta-methyl pyranosides and furanosides by combined g.l.c.-mass spectrometry and proton-magnetic-resonance spectroscopy. These data provide for the unambiguous interpretation of the gas chromatograms obtained in the application of this g.l.c. method, and supply basic information for the further application of mass spectrometry in this field.

Chromatography, Gas↗