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Biomedical subjects

J S Graham

Publications and source records attributed to J S Graham.

At least 37 records · Page 2Linked to original sources
PubMed1992

Complete amino Acid sequence of soybean leaf p21 : similarity to the thaumatin-like polypeptides.

A polypeptide structurally related to the thaumatin family of proteins has been purified from soybean (Glycine max) leaves and the complete amino acid sequence has been determined. The mature protein, which we have termed P21, has a calculated molecular weight of 21,461 and an isoelectric point of 4.6. The soybean protein shows 64% amino acid identity with thaumatin, a sweet-tasting protein found in the West African shrub Thaumatococcus danielli, and as much as 71% identity with thaumatin-like polypeptides present in tobacco and maize.

Journal Article↗
PubMed1992

Sequencing and characterization of the soybean leaf metalloproteinase : structural and functional similarity to the matrix metalloproteinase family.

A novel zinc endoproteinase has been sequenced and characterized from soybean leaves (Glycine max var Williams 82) and has been designated as Protein Identification Resource accession No. A41820 SMEP1 (soybean metalloendoproteinase 1). Comparison of the primary amino acid sequence with other zinc proteinases revealed the enzyme to be a new member of the matrix metalloproteinase (MMP) family of enzymes. SMEP was found to have MMP cleavage specificity toward peptide substrates and the enzyme is specifically inhibited by naturally occurring tissue inhibitors of MMPs through a high-affinity interaction (inhibitor concentration resulting in an approximate 50% decrease in enzyme activity = 23 x 10(-9) molar). Together, these results suggest that the origin of the MMP family of enzymes and their cognate inhibitors predates the divergence of plants and animals.

Journal Article↗
PubMed1992

Effect of ritanserin, a highly selective 5-HT2 receptor antagonist, on Parkinson's disease.

There is both experimental and clinical evidence to suggest a role for 5-hydroxytryptamine (5-HT) in Parkinson's disease. The effect of ritanserin, a highly selective 5-HT2 receptor antagonist, on Parkinsonian symptomatology was investigated in 10 patients in a single-blind placebo-controlled study. Akinesia and gait improved significantly in a dose-dependent manner in 5 and 7 patients respectively. However there was no significant improvement in tremor. The effects of ritanserin on akinesia and gait are consistent with a role for 5-HT in Parkinson's disease.

Aged↗
PubMed1991

Purification and Developmental Analysis of the Major Anionic Peroxidase from the Seed Coat of Glycine max.

We show that the majority of peroxidase activity in soybean (Glycine max var Williams 82) seeds is localized to the seed coat. A single isozyme is responsible for this activity and has been purified to electrophoretic homogeneity by successive chromatography on DEAE Sepharose Fast Flow, concanavalin A-Sepharose, and Sephadex G-75. The peroxidase exhibits a pl of 4.1, an apparent molecular mass of 37 kilodaltons, and has properties characteristic of a glycoprotein. The enzyme begins to accumulate approximately 21 days after anthesis and continues to do so throughout the maturation of the seed coat where it can represent at least 5% of the soluble protein in dry seed coats. Due to its localization in the seed, we propose that this isozyme may play a role in the hardening of the seed coat.

Journal Article↗
PubMed1991

Complete Amino Acid Sequence of a Polypeptide from Zea mays Similar to the Pathogenesis-Related-1 Family.

A polypeptide serologically related to the tobacco pathogenesis-related-1 family of proteins has been purified from the root tissue of maize (Zea mays L.), and the complete amino acid sequence has been determined. The mature protein has a calculated molecular weight of 14,970 and isoelectric point of 4.2. The maize protein shows 66 to 68% amino acid identity with the tobacco pathogenesis-related-1 family and 55% identity with the tomato p14 protein.

Journal Article↗
PubMed1991

Purification and Developmental Analysis of a Metalloendoproteinase from the Leaves of Glycine max.

A metalloendoproteinase from leaves of soybean (Glycine max) has been purified 1160-fold to electrophoretic homogeneity. The native protein is monomeric with a molecular mass of 15 kilodaltons as estimated by gel filtration and 19 kilodaltons as estimated by denaturing gel electrophoresis. The enzyme has a pH optima of 8.0 to 9.0 using Azocoll as substrate. The proteolytic activity is susceptible to metal chelating agents and the inactivated enzyme can be restored to 69% of original activity by the addition of ZnCl(2). Western analysis shows that a fraction of the soybean metalloendoproteinase is present within the extracellular space of older leaves. Soybean metalloendoproteinase 1 is the Azocollase A activity first described by Ragster and Chrispeels (Plant Physiol 64: 857-862; 1979).

Journal Article↗
PubMed1991

A comparison of standard Madopar and controlled release Madopar in Parkinson's disease.

In a randomised, double-blind cross-over study, objective measures were used to compare the effect of a single oral dose of a standard preparation of levodopa-benserazide (Madopar M) with a sustained-release preparation (Madopar HBS) in 9 Parkinsonian patients with 'end of dose deterioration'. The response of patients to an optimised regimen of each preparation was also assessed using a patient diary. In all patients the onset of effect of Madopar HBS following a single dose was delayed compared with Madopar M. The duration of effect of a single dose of Madopar HBS was substantially (38-120%) longer than Madopar M in five patients and the same or shorter in four patients. According to the patients' diaries, six patients noted an increase in 'on' hours while on Madopar HBS. The duration and severity of dyskinesia was similar for the two preparations. Madopar HBS is likely to be useful in some Parkinsonian patients with 'end of dose deterioration'. As the effect of each dose is delayed it is probably best given in combination with standard Madopar.

Adult↗
PubMed1990

P300 event-related potentials in de novo Parkinson's disease.

Recent studies indicate subtle cognitive deficits in many non-demented Parkinson's disease (PD) patients. Long-latency event-related potentials (LL-ERPs) index the nature and timing of a cognitive response to a stimulus and have been used to assess cognitive function in PD. Studies to date have only assessed patients receiving long-term anti-PD therapy, which may itself affect information processing. In this study we recorded the P300 using a standard auditory oddball paradigm with a button-press response in a group of de novo patients. A P300 was absent in 2 patients and prolonged in 2 patients but there was no difference in the latency or amplitude of the P300 in the Parkinsonian group compared with the age-matched control group. The averaged P300 of the young PD group was dispersed compared with that of the young controls. Our findings suggest that the amplitude and latency of P300 elicited using the paradigm of this study are not sensitive indices for differentiating PD patients from controls. A paradigm which places a greater load on the specific cognitive deficits of PD will be investigated. The dispersion of the P300 component in the young PD group may be support for the suggestion of distinct subgroups in PD. Our findings suggest that the latency and amplitude of LL-ERP components elicited by our paradigm were not sensitive indices for distinguishing PD patients from controls. The significance of the prolonged P3-RT measure is not clear.

Adult↗
PubMed1989

Phosphorylation status of nuclear and cytosolic androgen receptors in the rat ventral prostate.

We demonstrate that endogenous phosphatases are active in cytosolic and nuclear androgen receptor fractions from the rat ventral prostate. Under our androgen binding assay conditions, the effect of acid phosphatase inhibitors (sodium fluoride, tartaric acid, sodium orthovanadate) on the endogenous phosphatases could be correlated with an increase in dihydrotestosterone (DHT) binding to fractions of partially purified cytosolic androgen receptor. In contrast, tetramisole, an alkaline phosphatase inhibitor, did not alter the binding of DHT to the same receptor fraction. Immunoprecipitation of androgen receptor fractions with polyclonal anti-phosphotyrosine antibody resulted in the recovery of [3H]-DHT binding activity from nuclear receptor fractions and partially purified cytosolic receptor fractions prepared from 20- to 24-hr castrated rats. In control fractions depleted of androgen receptor, negligible levels of binding activity were recovered following immunoprecipitation with the antibody. Therefore, acid phosphatases may be acting on phosphotyrosyl residues of the androgen receptor, thus playing a role in the dephosphorylation and inactivation of the androgen receptor.

Animals↗
PubMed1987

Radiolabeling of a wound-inducible pyridoxal phosphate-utilizing enzyme: evidence for its identification as ACC synthase.

1-Aminocyclopropane-1-carboxylic acid (ACC) synthase, a pyridoxal phosphate-utilizing enzyme, catalyzes the conversion of S-adenosylmethionine to ACC, the rate-limiting step in the biosynthesis of the plant hormone ethylene. We report the partial purification (400-fold) of ACC synthase from wounded pink tomato pericarp. Further purification results in a decrease in specific activity apparently due to the instability of the enzyme. Radiolabeling of a pyridoxal phosphate-utilizing protein in the ACC synthase-enriched fraction was achieved by reduction using tritiated sodium borohydride. Evidence that this radiolabeled protein is ACC synthase is presented.

Autoradiography↗
PubMed1987

Cardiomyopathy in Soman and Sarin intoxicated rats.

Rats surviving various single dose of the organophosphorus anticholinesterase nerve agents Soman and Sarin were examined by light microscopy at intervals up to 35 days post-exposure. Brain lesions, identical to those that have been reported elsewhere were present, as well as a previously unreported finding associated with Soman or Sarin intoxication: half of all animals that had brain lesions also had areas of myocardial degeneration and necrosis. Depending upon the point in time at which cardiac tissues were examined, findings varied from areas of acute myolysis and necrosis to areas undergoing resolution of damage. The finding of brain lesions in those animals having cardiac lesions suggests a relationship between the convulsion induced neurologic and cardiac lesions. These studies suggest that convulsive doses of chemical warfare agents induce pathological changes in the cardiovascular system of laboratory animals.

Animals↗
PubMed1986

Regulation of proteinase inhibitor genes in food plants.

Proteinase inhibitor proteins in the families Solanaceae, Leguminosae and Graminae are stored in seeds and tubers and are also found to accumulate in leaves in response to pest attacks. The isolation of the proteinase Inhibitor I cDNA and its gene from tomato has provided information concerning proteinase inhibitor synthesis, processing and compartmentation in leaves under pest attacks. Strategies are now being developed using proteinase inhibitor genes, to genetically engineer the quantity and quality of these potentially defensive and highly nutritional proteins of important crop plants.

Amino Acid Sequence↗
PubMed1986

Molecular characterization and phylogenetic studies of a wound-inducible proteinase inhibitor I gene in Lycopersicon species.

A gene coding for proteinase inhibitor I, whose expression is induced in tomato leaves (Lycopersicon esculentum L. var. Bonny Best) in response to wounding or insect attacks, was isolated from a genomic library and characterized. The nucleotide sequence revealed that the gene is complete and encodes the sequence of an inhibitor I cDNA that was previously isolated from a cDNA library prepared from wound-induced mRNA from tomato leaves. This gene is located 13.1 kilobase pairs (kbp) upstream from an inhibitor II gene. The wound-inducible gene is interrupted by two intervening sequences of 445 and 404 bp, situated within the codons of amino acids 17 and 47, respectively, of the open reading frame. In addition to the presence of putative regulatory sequences, TATAAA and CCACT, two copies of an imperfect direct repeat approximately 100 bp long were identified in the 5'-flanking region. Phylogenetic comparisons of wound-inducible inhibitor I genes within the genomes of various Lycopersicon species revealed that the repeat is found in seven ancestral species of tomato.

Amino Acid Sequence↗
PubMed1985

Wound-induced proteinase inhibitors from tomato leaves. I. The cDNA-deduced primary structure of pre-inhibitor I and its post-translational processing.

A cDNA containing the coding region for the complete amino acid sequence of wound-induced proteinase Inhibitor I from tomato leaves was constructed in the plasmid pUC9 and characterized. The open reading frame codes for a protein of 111 amino acids. This deduced amino acid sequence revealed the presence of a 42-amino acid N-terminal sequence that is not found in the native protein. This sequence appears to contain a 23-amino acid segment typical of a signal sequence followed by a 19-amino acid sequence containing 9 charged amino acids. The 42-amino acid sequence is apparently lost during maturation to the native Inhibitor I and represents 38% of the translated protein. The Inhibitor I amino acid sequence contains 71% identity with potato tuber Inhibitor I sequence and 35% identity with an inhibitor from the leech.

Amino Acid Sequence↗
PubMed1985

Wound-induced proteinase inhibitors from tomato leaves. II. The cDNA-deduced primary structure of pre-inhibitor II.

A cDNA containing the complete amino acid-coding region of wound-induced tomato Inhibitor II was constructed in the plasmid pUC9. The open reading frame codes for 148 amino acids including a 25-amino acid signal sequence preceding the N-terminal lysine of the mature Inhibitor II. The Inhibitor II sequence exhibits two domains, one domain having a trypsin inhibitory site and the other a chymotrypsin inhibitory site, apparently evolved from a smaller gene by a process of gene duplication and elongation. The amino acid sequence of tomato leaf Inhibitor II exhibits homology with two small proteinase inhibitors isolated from potato tuber and an inhibitor from eggplant. The small potato tuber inhibitors are homologous with 33 amino acids of the N-terminal domain and 19 amino acids from the C-terminal domain. Two identical nucleotide sequences of Inhibitor II cDNA in the 3' noncoding region were present that were also found in an Inhibitor I cDNA. These include an atypical polyadenylation signal, AATAAG, and a 10-base palindromic sequence, CATTATAATG, for which no function is yet known.

Amino Acid Sequence↗
PubMed1981

Multiple sclerosis: capping of surface immunoglobulin G on macrophages engaged in myelin breakdown.

Macrophages were examined for immunoglobulin G (IgG) and albumin in actively demyelinating lesions in two patients with multiple sclerosis (MS) using the peroxidase-antiperoxidase immunocytochemical technique. In both cases, macrophages were present that stained for cytoplasmic or surface IgG or both. In one case, in which the tissue was rapidly fixed in chilled fixative, macrophages located among myelinated nerve fibers at plaque margins, but not elsewhere in the plaque, revealed surface IgG in the form of caps restricted to one or both poles of the cell. These caps were absent in sections stained for albumin. Because capping implies the presence of a multivalent ligand close to the cell surface and because cap formation was observed only in macrophages contacting myelin sheaths, we suggest that antimyelin antibody cytophilic for macrophages may be present in the central nervous system in MS, and that immune ligand-mediated phagocytosis may play a role in myelin breakdown in the disease. This study provides the first direct evidence that IgG participates locally in myelin breakdown in MS.

Adult↗