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Jonathan Love

Publications and source records attributed to Jonathan Love.

7 recordsLinked to original sources
PubMed2006

Biosynthesis of cellulose-enriched tension wood in Populus: global analysis of transcripts and metabolites identifies biochemical and developmental regulators in secondary wall biosynthesis.

Stems and branches of angiosperm trees form tension wood (TW) when exposed to a gravitational stimulus. One of the main characteristics of TW, which distinguishes it from normal wood, is the formation of fibers with a thick inner gelatinous cell wall layer mainly composed of crystalline cellulose. Hence TW is enriched in cellulose, and deficient in lignin and hemicelluloses. An expressed sequence tag library made from TW-forming tissues in Populus tremula (L.) x tremuloides (Michx.) and data from transcript profiling using microarray and metabolite analysis were obtained during TW formation in Populus tremula (L.) in two growing seasons. The data were examined with the aim of identifying the genes responsible for the change in carbon (C) flow into various cell wall components, and the mechanisms important for the formation of the gelatinous cell wall layer (G-layer). A specific effort was made to identify carbohydrate-active enzymes with a putative function in cell wall biosynthesis. An increased C flux to cellulose was suggested by a higher abundance of sucrose synthase transcripts. However, genes related to the cellulose biosynthetic machinery were not generally affected, although the expression of secondary wall-specific CesA genes was modified in both directions. Other pathways for which the data suggested increased activity included lipid and glucosamine biosynthesis and the pectin degradation machinery. In addition, transcripts encoding fasciclin-like arabinogalactan proteins were particularly increased and found to lack true Arabidopsis orthologs. Major pathways for which the transcriptome and metabolome analysis suggested decreased activity were the pathway for C flux through guanosine 5'-diphosphate (GDP) sugars to mannans, the pentose phosphate pathway, lignin biosynthesis, and biosynthesis of cell wall matrix carbohydrates. Several differentially expressed auxin- and ethylene-related genes and transcription factors were also identified.

Cell Wall↗
PubMed2005

The role of ciprofloxacin in prolonging polyethylene biliary stent patency: a multicenter, double-blinded effectiveness study.

Plastic stents are the mainstay of the palliation of malignant jaundice but are complicated by recurrent obstruction. Previous trials have failed to demonstrate any improvement in patency with the use of antibiotics. Patients with malignant jaundice were randomized in a double-blind fashion, after polyethylene stent insertion, to receive ciprofloxacin or placebo. After successful stent decompression, there were 50 patients in the treatment arm and 44 in the placebo. There were 14 (33%) episodes of stent occlusion in the ciprofloxacin group versus 23 (49%) in placebo (chi(2) test, P=0.115). There was no significant difference in patency (log-rank test, P=0.17). There were significantly fewer episodes of cholangitis with ciprofloxacin: 10 (23%) versus 21 (42%) in the placebo (P=0.047). The ciprofloxacin group also demonstrated a significant improvement in the Social Function domain of the SF-36 Quality of Life Survey at 1 month (paired T test, P=0.03). The other domains of the SF-36 were not different, nor was survival (log rank, P=0.80). There is insufficient evidence to show that prophylactic ciprofloxacin can prolong plastic biliary stent patency. The observed trends suggest that ciprofloxacin significantly decreases the incidence of cholangitis and results in improvements in certain aspects of quality of life.

Adult↗
PubMed2004

Endoscopic sphincterotomy by using pure-cut electrosurgical current and the risk of post-ERCP pancreatitis: a prospective randomized trial.

BACKGROUND: It has been suggested that the use of pure-cut electrosurgical current for endoscopic sphincterotomy may reduce the risk of post-ERCP pancreatitis. The aim of this study was to determine whether pure-cut current reduces the risk of pancreatitis compared with blend current. METHODS: Patients were randomly assigned to undergo sphincterotomy over a non-conductive guidewire with 30 W/sec pure-cut current or 30 W/sec blend-2 current by a blinded endoscopist. Serum amylase and lipase levels were determined 1 day before and within 24 hours after ERCP. Post-ERCP pancreatitis was the primary outcome of interest. Secondary outcomes were as follows: severity of immediate bleeding, as graded by a 3-point scale from 1 (no bleeding) to 3 (injection or balloon tamponade therapy required to stop bleeding) and evidence of delayed bleeding 24 hours after ERCP. Analyses were performed in intention-to-treat fashion. RESULTS: A total of 246 patients were randomized (116 pure-cut current, 130 blend current). There were no differences in baseline characteristics between the groups. The overall frequency of post-ERCP pancreatitis was 6.9%, with no significant difference in frequency between treatment arms (pure cut, 7.8% vs. blend, 6.1%; p = 0.62). The difference in rates of pancreatitis between the two groups was 1.7%: 95% CI[-4.8%, 8.2%]. Six patients (2.4%) had delayed bleeding after ERCP, of which two required transfusion. There was a significant increase in minor bleeding episodes (grade 2) in the pure-cut group (p < 0.0001). Delayed episodes of bleeding were equal (n = 3) in each arm. CONCLUSIONS: The type of current used when performing endoscopic sphincterotomy does not appear to alter the risk of post-ERCP pancreatitis. The selection of electrosurgical current for biliary endoscopic sphincterotomy should be based on endoscopist preference.

Adult↗
PubMed2004

Varying time delay Smith predictor process controller.

One of the perceived weaknesses of the classical Smith predictor is that the time delay is fixed. For systems with a varying time delay, underestimating or overestimating the time delay significantly degrades control quality. This paper presents theoretical and practical results of applying the Smith predictor with a varying time delay when the nature of the application allows the time delay to be practically computed in real time.

Journal Article↗