bluuebunny/crossref_metadata_2025_split huggingface dataset:
A mixed mechanistic‐electrostatic model to explain pH dependence of glycosyl hydrolase enzyme activity
Authors: Olivera‐Nappa Alvaro , Andrews Barbara A. , Asenjo Juan A. 
Published: April 2004

AbstractGlycosyl hydrolases are a vast group of enzymes that share a common topology at their active site with two acidic residues that are responsible for activity. In spite of their similarity, they exhibit a wide range of pH optima that must depend on other factors. Using structural and mechanistic knowledge about glycosyl hydrolases from families 7, 10, and 16, we have formulated a new mathematical model that can include not only the ionization behavior of the catalytic residues but also as many ionizable residues as desired in the active site. In addition, the model can incorporate electrostatic influences via acid dissociation equilibrium constants and chemical relationships such as hydrogen bonds. The results of the simulations indicate a clear shift in the pH dependence of activity for the enzymes only when a close interrelation (hydrogen bond) between the catalytic and auxiliary residues in the active site is taken into account. This explains the observations from mutagenesis studies that show this type of shift and cannot be explained by a purely electrostatic interaction theory. Moreover, the presence of the kind of chemical interaction proposed could provide stabilization of the activity in the presence of environmental, structural, pH and electrostatic variations. These findings and the implications for the design of new mutagenesis strategies are discussed. The results suggest a way to modify, via site‐directed mutagenesis, the acid dissociation of one of the catalytic residues in the active site independently of the other, which could have clear advantages over the purely electrostatic modifications that usually affect both residues simultaneously. © 2004 Wiley Periodicals, Inc.
Novel synthetic jasmonates as highly efficient elicitors for taxoid production by suspension cultures of Taxus chinensis
Authors: Qian Zhi‐Gang , Zhao Zhen‐Jiang , Tian Wen‐Hong , Xu Yufang , Zhong Jian‐Jiang , Qian Xuhong 
Published: April 2004

AbstractSuspension cultures of Taxus chinensis were used as a model plant cell system to evaluate novel synthetic jasmonates as elicitors for stimulating the biosynthesis of secondary metabolites. Significant increases in accumulation of taxuyunnanine C (Tc) were observed in the presence of newly synthesized 2‐hydroxyethyl jasmonate (HEJA) and trifluoroethyl jasmonate (TFEJA) without their inhibition on cell growth. Addition of 100 μM HEJA or TFEJA on day 7 led to a high Tc content of 44.3 ± 1.1mg/g or 39.7 ± 1.1 mg/g (at day 21), while the Tc content was 14.0 ± 0.1 mg/g and 32.4 ± 1.6 mg/g for the control and that with addition of 100 μM methyl jasmonate (MJA), respectively. The superior stimulating ability of HEJA and TFEJA over MJA, which was generally considered as the best chemical for eliciting taxoid biosynthesis, suggests that the novel jasmonate analogues may have great potential in application to other cell culture systems for effcient elicitation of plant secondary metabolites. © 2004 Wiley Periodicals, Inc.
Fermentation of biomass‐generated producer gas to ethanol
Authors: Datar Rohit P. , Shenkman Rustin M. , Cateni Bruno G. , Huhnke Raymond L. , Lewis Randy S. 
Published: April 2004

AbstractThe development of low‐cost, sustainable, and renewable energy sources has been a major focus since the 1970s. Fuel‐grade ethanol is one energy source that has great potential for being generated from biomass. The demonstration of the fermentation of biomass‐generated producer gas to ethanol is the major focus of this article in addition to assessing the effects of producer gas on the fermentation process. In this work, producer gas (primarily CO, CO2, CH4, H2, and N2) was generated from switchgrass via gasification. The fluidized‐bed gasifier generated gas with a composition of 56.8% N2, 14.7% CO, 16.5% CO2, 4.4% H2, and 4.2% CH4. The producer gas was utilized in a 4‐L bioreactor to generate ethanol and other products via fermentation using a novel clostridial bacterium. The effects of biomass‐generated producer gas on cell concentration, hydrogen uptake, and acid/alcohol production are shown in comparison with “clean” bottled gases of similar compositions for CO, CO2, and H2. The successful implementation of generating producer gas from biomass and then fermenting the producer gas to ethanol was demonstrated. Several key findings following the introduction of producer gas included: (1) the cells stopped growing but were still viable, (2) ethanol was primarily produced once the cells stopped growing (ethanol is nongrowth associated), (3) H2 utilization stopped, and (4) cells began growing again if “clean” bottled gases were introduced following exposure to the producer gas. © 2004 Wiley Periodicals, Inc.
Influence of β‐subunit on thermal and high‐pressure process stability of tomato polygalacturonase
Authors: Peeters Liesbet , Fachin Diana , Smout Chantal , van Loey Ann , Hendrickx Marc E. 
Published: April 2004

AbstractPolygalacturonase (PG; E.C. 3.2.1.15) was extracted from tomato fruit and purified by cation‐exchange chromatography. Two peaks containing PG activity were detected: the first denotes a thermolabile PG fraction (PG2) and the second a thermostable fraction (PG1). PG1 is a dimer of PG2 and a heat‐stable protein called the β‐subunit. In contrast to its resistance to heat, PG is easily inactivated at elevated pressure. Although the thermal stability of purified tomato PG1 and PG2 is distinctly different, they show an identical pressure stability. To gain further insight into the thermal and pressure stability of both PG isoenzymes, the in vitro recombination of PG2 and β‐subunit was studied. After severe heat (up to 140°C for 5 min) and pressure (up to 800 MPa for 15 min) treatments, the residual fractions containing the β‐subunit were able to convert PG2 into the heat‐stable PG1, showing the extreme thermal and pressure stability of the β‐subunit. PG1 was detected in heat‐treated tomato juice and, to a lesser extent, in tomato pieces. In contrast, as was the case for purified PG, no pressure‐stable fraction was observed when tomato juice and pieces were treated under pressure. These data clearly show the differing behavior of the PG1–PG2–β‐subunit system under thermal and high‐pressure treatments and offer the possibility of inactivating tomato PG using high pressure without the need for high temperatures. © 2004 Wiley Periodicals, Inc.
Emergency presentation of colorectal cancer is associated with poor 5-year survival
Authors: McArdle C S , Hole D J 
Published: April 2004

Abstract

Background
Previous studies have reported that emergency presentation of colorectal cancer is associated with poor outcome. Many of these studies were small and most were not adjusted for case mix. The aim of this study was to establish, after adjusting for case mix, the magnitude of the differences in postoperative mortality and survival between patients undergoing elective surgery and those presenting as an emergency.

Methods
Three thousand two hundred patients who underwent surgery for colorectal cancer between 1991 and 1994 in Scotland were studied. Five-year survival rates and adjusted hazard ratios were calculated.

Results
Some 1603 (72·4 per cent) of 2214 elective patients had a potentially curative resection compared with 632 (64·1 per cent) of 986 patients who presented as an emergency (P &lt; 0·001). Following curative resection, the postoperative mortality rate was 2·8 per cent after elective and 8·2 per cent after emergency operation (P &lt; 0·001). Overall survival at 5 years was 57·5 per cent after elective and 39·1 per cent after emergency curative surgery (P &lt; 0·001); cancer-specific survival at 5 years was 70·9 and 52·9 per cent respectively (P &lt; 0·001). The adjusted hazard ratio for overall survival after emergency relative to elective surgery was 1·68 (95 per cent confidence interval (c.i.) 1·49 to 1·90; P &lt; 0·001) and that for cancer-specific survival was 1·90 (95 per cent c.i. 1·62 to 2·22; P &lt; 0·001).

Conclusion
Following apparently curative resection for colorectal cancer, there was an excess of both cancer-related and intercurrent deaths in patients who presented as an emergency.
Use of the time–signal intensity curve from dynamic magnetic resonance imaging to evaluate remnant pancreatic fibrosis after pancreaticojejunostomy in patients undergoing pancreaticoduodenectomy
Authors: Tajima Y , Matsuzaki S , Furui J , Isomoto I , Hayashi K , Kanematsu T 
Published: April 2004

Abstract

Background
This study assessed the value of the time–signal intensity curve (TIC) obtained from dynamic magnetic resonance imaging (MRI) in the evaluation of remnant pancreatic fibrosis after pancreaticojejunostomy in patients undergoing pancreaticoduodenectomy.

Methods
Two modes of pancreaticojejunostomy—duct-to-mucosa anastomosis (DMA; 24 patients) and pancreatojejunoserosal anastomosis (PJSA; 22 patients)—were used in 46 consecutive patients undergoing pancreaticoduodenectomy. All patients underwent dynamic contrast-enhanced MRI of the pancreas before pancreaticoduodenectomy. Retrospective review of the pancreatic magnetic resonance images and histological examination of the pancreas were performed, and the patterns of TICs from dynamic MRI were compared with the degree of pancreatic fibrosis. Dynamic MRI of the residual pancreas was carried out for 1–3 years after pancreaticoduodenectomy in 26 patients (14 DMA, 12 PJSA) who had a histologically verified normal pancreas with no fibrosis at the time of pancreaticoduodenectomy.

Results
Evaluation of preoperative dynamic magnetic resonance images showed that a pancreatic TIC with a rapid rise to a peak followed by a rapid decline (type I) was characteristic of a normal pancreas without fibrosis. Pancreatic TICs with a slow rise to a peak followed by a slow decline or a plateau (types II and III) indicated a fibrotic pancreas. Postoperative pancreatic MRI demonstrated that six of 12 patients with a PJSA had a type II TIC, whereas 12 of 14 patients with a DMA had a type I curve (P = 0·046).

Conclusion
The TIC obtained from dynamic MRI is a reliable indicator of fibrosis in the remnant pancreas after pancreaticoduodenectomy. Use of a DMA was associated with a lower risk of pancreatic fibrosis 1–3 years after surgery than a PJSA.
Infrared ray electronic endoscopy combined with indocyanine green injection for detection of sentinel nodes of patients with gastric cancer
Authors: Nimura H , Narimiya N , Mitsumori N , Yamazaki Y , Yanaga K , Urashima M 
Published: April 2004

Abstract

Background
To avoid unnecessary lymphadenectomy in patients with cancer accurate diagnosis of the sentinel lymph node (SLN) is important.

Methods
This report examined the initial clinical use of infrared ray electronic endoscopy (IREE) combined with indocyanine green (ICG) injection for SLN detection in 84 patients with gastric cancer not invading the subserosa (75 T1 N0 M0 and nine T2 N0 M0 tumours, according to tumour node metastasis classification).

Results
There were no adverse events after injection of ICG. At least one SLN was detected in all but one patient by both ICG injection alone and by IREE with ICG. Eleven of the 84 patients had lymph node metastasis. SLNs detected by ICG injection alone did not include metastases in four of 11 patients, whereas IREE with ICG detected SLNs containing lymph node metastases in all 11 patients. Moreover, SLNs illuminated by IREE with ICG included all metastases among the 105 regional lymph nodes in the 11 patients; no metastatic lymph nodes were identified among 154 non-SLNs.

Conclusion
IREE combined with ICG injection may efficiently detect SLNs that contain metastases in patients with gastric cancer.
Influence of volume and specialization on survival following surgery for colorectal cancer
Authors: McArdle C S , Hole D J 
Published: April 2004

AbstractBackgroundPrevious studies have shown that significant surgeon-related differences in survival exist following surgery for colorectal cancer. It is not clear whether these differences were due to differences in caseload or degree of specialization.MethodsOutcome in 3200 patients who underwent resection for colorectal cancer between 1991 and 1994 was analysed on the basis of caseload and degree of specialization of individual surgeons. Five-year survival rates, and the corresponding hazard ratios adjusted for case mix, were calculated.ResultsCancer-specific survival rate at 5 years following curative resection varied among surgeons from 53·4 to 84·6 per cent; the adjusted hazard ratios varied from 0·48 to 1·55. Cancer-specific survival rate at 5 years following curative resection was 70·2, 62·0 and 65·9 per cent for surgeons with a high, medium and low case volume respectively. There were no consistent differences in the adjusted hazard ratios by volume. Cancer-specific survival rate at 5 years following curative resection was 72·7 per cent for those treated by specialists and 63·8 per cent for those treated by non-specialists; the adjusted hazard ratio for non-specialists was 1·35 (95 per cent confidence interval 1·13 to 1·62; P = 0·001).ConclusionThe differences in outcome following apparently curative resection for colorectal cancer among surgeons appear to reflect the degree of specialization rather than case volume. It is likely that increased specialization will lead to further improvements in survival.
Randomized clinical trial of laparoscopic versus open fundoplication for gastro-oesophageal reflux
Authors: Nilsson G , Wenner J , Larsson S , Johnsson F 
Published: April 2004

Abstract

Background
The aim of this study was to compare the long-term results of laparoscopic and open antireflux surgery in a randomized clinical trial by investigating subjective and objective outcomes.

Methods
Sixty patients with gastro-oesophageal reflux disease (GORD) were randomized to laparoscopic or open 360 ° fundoplication. Subjective evaluation using disease-specific and generic questionnaires and structured interviews, and objective evaluation by endoscopy, oesophageal manometry and 24-h pH monitoring, were performed before operation and 1 month, 6 months and 5 years after surgery.

Results
Two patients in the laparoscopic group had reoperations for hiatal stricture; one patient in the open group had repair of an incisional hernia, and one patient in each group had surgery for intestinal obstruction. There were no differences in the subjective outcomes of diet, sleep, medication, patient satisfaction and symptoms of GORD after 5 years. Nor were there any differences in objective outcomes determined by endoscopy, manometry or 24-h pH monitoring. Well-being was decreased in all patients before operation but was restored to normal or above-normal values after fundoplication, regardless of the type of surgery. Seven of 28 patients in the open group had complaints regarding the scar.

Conclusion
Elimination of GORD symptoms improved well-being and eliminated the need for daily acid suppression in most patients, no matter which procedure was employed. These results were apparent 1 month after the operation and were still valid 5 years later.
Curative resection is the single most important factor determining outcome in patients with pancreatic adenocarcinoma
Authors: Wagner M , Redaelli C , Lietz M , Seiler C A , Friess H , Büchler M W 
Published: April 2004

AbstractBackgroundMortality rates associated with pancreatic resection for cancer have steadily decreased with time, but improvements in long-term survival are less clear. This prospective study evaluated risk factors for survival after resection for pancreatic adenocarcinoma.MethodsData from 366 consecutive patients recorded prospectively between November 1993 and September 2001 were analysed using univariate and multivariate models.ResultsFifty-eight patients (15·8 per cent) underwent surgical exploration only, 97 patients (26·5 per cent) underwent palliative bypass surgery and 211 patients (57·7 per cent) resection for pancreatic adenocarcinoma. Stage I disease was present in 9·0 per cent, stage II in 18·0 per cent, stage III in 68·7 per cent and stage IV in 4·3 per cent of patients who underwent resection. Resection was curative (R0) in 75·8 per cent of patients. Procedures included pylorus-preserving Whipple resection (41·2 per cent), classical Whipple resection (37·0 per cent), left pancreatic resection (13·7 per cent) and total pancreatectomy (8·1 per cent). The in-hospital mortality and cumulative morbidity rates were 2·8 and 44·1 per cent respectively. The overall actuarial 5-year survival rate was 19·8 per cent after resection. Survival was better after curative resection (R0) (24·2 per cent) and in lymph-node negative patients (31·6 per cent). A Cox proportional hazards survival analysis indicated that curative resection was the most powerful independent predictor of long-term survival.ConclusionResection for pancreatic adenocarcinoma can be performed safely. The overall survival rate is determined by the radicality of resection. Patients deemed fit for surgery who have no radiological signs of distant metastasis should undergo surgical exploration. Resection should follow if there is a reasonable likelihood that an R0 resection can be obtained.
Randomized clinical trial of distal anastomotic interposition vein cuff in infrainguinal polytetrafluoroethylene bypass grafting
Authors: Griffiths G D , Nagy J , Black D , Stonebridge P A 
Published: April 2004

Abstract

Background
The aim was to examine the effect of a Miller vein cuff at the distal anastomosis on the medium- to long-term patency and limb salvage rates of femoral to above-knee and femoral to below-knee popliteal artery polytetrafluoroethylene (PTFE) bypasses.

Methods
This study involved extended follow-up of the original cohort of patients included in a previously reported multicentre randomized clinical study. Outcome measures were bypass graft patency and limb salvage.

Results
Two hundred and sixty-one bypass operations were originally randomized. For this study, full data were available on 235 (120 with a Miller cuff, 115 without). The cumulative 5-year patency rate for above-knee bypasses with a Miller cuff was 40 per cent, compared with 42 per cent for non-cuffed bypasses (P = 0·702). The cumulative 3-year patency rate for below-knee bypasses with a Miller cuff was 45 per cent, compared with 19 per cent for non-cuffed bypasses (P = 0·018). A Miller cuff had no significant effect on limb salvage for above-knee or below-knee bypasses.

Conclusion
Three-year patency rates of femoral to below-knee popliteal PTFE bypasses were improved by a Miller cuff. Miller cuffs had no effect on patency rates for femoral to above-knee popliteal bypasses at 5 years and did not improve limb salvage in either group.
Total thyroidectomy for clinically benign disease of the thyroid gland
Authors: Bron L P , O'Brien C J 
Published: April 2004

Abstract

Background
The role of total thyroidectomy in the treatment of patients with benign thyroid disease remains controversial. However, this procedure may be appropriate when both thyroid lobes are involved and when the risk of recurrence is significant. This study is a review of a 15-year experience of total thyroidectomy for benign disease.

Methods
Between 1988 and 2002, 834 patients underwent total thyroidectomy for clinically benign disease at the Sydney Head and Neck Cancer Institute, Royal Prince Alfred Hospital. There were 128 men and 706 women with a mean age of 52 (range 16–91) years. Indications for surgery were euthyroid multinodular goitre (MNG), toxic MNG and Graves' disease in 730 (87·5 per cent), 57 (6·8 per cent) and 47 (5·6 per cent) respectively. A total of 74 patients had previously undergone partial thyroidectomy.

Results
The incidence of temporary recurrent laryngeal nerve palsy was 2·3 per cent and that of temporary hypoparathyroidism 14·4 per cent. Permanent recurrent laryngeal nerve palsy occurred in 1·1 per cent, and 2·4 per cent of patients had permanent hypoparathyroidism. Neither the initial clinical diagnosis nor a history of previous treatment significantly influenced the rate of complications. The incidence of malignancy, other than incidental microscopic papillary carcinoma, was 4·6 per cent.

Conclusion
Total thyroidectomy has an important role in the management of patients with benign disease when both lobes of the thyroid gland are involved. This approach avoids disease recurrence and the increased risk of morbidity associated with secondary operation.
Working capacity and resting energy expenditure after ileal pouch–anal anastomosis
Authors: Öhrström M , Jansson O , Wohlfart B , Ekelund M 
Published: April 2004

Abstract

Background
The aim was to evaluate the working capacity and resting energy expenditure in patients who had undergone restorative proctocolectomy.

Methods
Of 72 patients operated on between April 1990 to September 1998, 51 were eligible and 38 participated in the study. Resting energy was assessed by indirect calorimetry, and working capacity by ergospirometry on an exercise bicycle.

Results
The median functional score was 2 (range 0–7). Oxygen uptake during rest was reduced for men compared with predicted values. The corresponding values for women were in keeping with predicted values. The median working capacity was 96 (range 59–102) per cent for women and 91 (range 51–113) per cent for men, compared with reference values of maximum workload based on age, height and sex. There was no correlation between functional score and any other variable measured.

Conclusion
Patients who have undergone restorative proctocolectomy for ulcerative colitis have normal resting energy expenditure and working capacity.
Fistuloclysis can successfully replace parenteral feeding in the nutritional support of patients with enterocutaneous fistula
Authors: Teubner A , Morrison K , Ravishankar H R , Anderson I D , Scott N A , Carlson G L 
Published: April 2004

Abstract

Background
Use of total parenteral nutrition (TPN) in patients with acute intestinal failure due to enteric fistulation might be avoided if a simpler means of nutritional support was available. The aim of this study was to determine whether feeding via an intestinal fistula (fistuloclysis) would obviate the need for TPN.

Methods
Fistuloclysis was attempted in 12 patients with jejunocutaneous or ileocutaneous fistulas with mucocutaneous continuity. Feeding was achieved by inserting a gastrostomy feeding tube into the intestine distal to the fistula. Infusion of enteral feed was increased in a stepwise manner, without reinfusion of chyme, until predicted nutritional requirements could be met by a combination of fistuloclysis and regular diet, following which TPN was withdrawn. Energy requirements and nutritional status were assessed before starting fistuloclysis and at the time of reconstructive surgery.

Results
Fistuloclysis replaced TPN entirely in 11 of 12 patients. Nutritional status was maintained for a median of 155 (range 19–422) days until reconstructive surgery could be safely undertaken in nine patients. Two patients who did not undergo surgery remained nutritionally stable over at least 9 months. TPN had to be recommenced in one patient. There were no complications associated with fistuloclysis.

Conclusion
Fistuloclysis appears to provide effective nutritional support in selected patients with enterocutaneous fistula.