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Biomedical subjects

R J Hull

Publications and source records attributed to R J Hull.

6 recordsLinked to original sources
PubMed2000

Characterization of cucurbita maxima phloem serpin-1 (CmPS-1). A developmentally regulated elastase inhibitor.

We report on the molecular, biochemical, and functional characterization of Cucurbita maxima phloem serpin-1 (CmPS-1), a novel 42-kDa serine proteinase inhibitor that is developmentally regulated and has anti-elastase properties. CmPS-1 was purified to near homogeneity from C. maxima (pumpkin) phloem exudate and, based on microsequence analysis, the cDNA encoding CmPS-1 was cloned. The association rate constant (k(a)) of phloem-purified and recombinant His(6)-tagged CmPS-1 for elastase was 3.5 +/- 1.6 x 10(5) and 2.7 +/- 0.4 x 10(5) m(-)(1) s(-)(1), respectively. The fraction of complex-forming CmPS-1, X(inh), was estimated at 79%. CmPS-1 displayed no detectable inhibitory properties against chymotrypsin, trypsin, or thrombin. The elastase cleavage sites within the reactive center loop of CmPS-1 were determined to be Val(347)-Gly(348) and Val(350)-Ser(351) with a 3:2 molar ratio. In vivo feeding assays conducted with the piercing-sucking aphid, Myzus persicae, established a close correlation between the developmentally regulated increase in CmPS-1 within the phloem sap and the reduced ability of these insects to survive and reproduce on C. maxima. However, in vitro feeding experiments, using purified phloem CmPS-1, failed to demonstrate a direct effect on aphid survival. Likely roles of this novel phloem serpin in defense against insects/pathogens are discussed.

Amino Acid Sequence↗
PubMed1995

Transfusion-associated chronic cutaneous graft-versus-host disease.

Transfusion-associated graft-versus-host disease (TAGVHD) occurs in immunocompromised persons who receive nonirradiated blood products containing immunologically competent donor lymphocytes. TAGVHD occurs almost exclusively as an acute illness and has a very high mortality rate. We describe a patient with a long history of non-Hodgkin's lymphoma in whom acute TAGVHD developed after transfusion of packed red blood cells from two unrelated donors. TAGVHD developed despite pretreatment of the transfused units with white blood cell filters. The patient survived and subsequently had clinical manifestations typical of chronic cutaneous graft-versus-host disease. HLA phenotyping studies suggested that elements from both transfusion donors engrafted. TAGVHD is a rare but probably underdiagnosed disorder that, although usually fatal, may evolve into chronic graft-versus-host disease. Treatment of blood products with white blood cell filters does not appear adequate to prevent TAGVHD.

Aged↗
PubMed1992

Secondary plasmodesmata are specific sites of localization of the tobacco mosaic virus movement protein in transgenic tobacco plants.

Expression of the tobacco mosaic virus 30-kD movement protein (TMV MP) gene in tobacco plants increases the plasmodesmatal size exclusion limit (SEL) 10-fold between mesophyll cells in mature leaves. In the present study, we examined the structure of plasmodesmata as a function of leaf development. In young leaves of 30-kD TMV MP transgenic (line 274) and vector control (line 306) plants, almost all plasmodesmata were primary in nature. In both plant lines, secondary plasmodesmata were formed, in a basipetal pattern, as the leaves underwent expansion growth. Ultrastructural and immunolabeling studies demonstrated that in line 274 the TMV MP accumulated predominantly in secondary plasmodesmata of nonvascular tissues and was associated with a filamentous material. A developmental progression was detected in terms of the presence of TMV MP; all secondary plasmodesmata in the tip of the fourth leaf contained TMV MP in association with the filamentous material. Dye-coupling experiments demonstrated that the TMV MP-induced increase in plasmodesmatal SEL could be routinely detected in the tip of the fourth leaf, but was restricted to mesophyll and bundle sheath cells. These findings are discussed with respect to the structure and function of plasmodesmata, particularly those aspects related to virus movement.

Cytoplasm↗