bluuebunny/crossref_metadata_2025 huggingface dataset:
Validity of surgical simulation for the assessment of operative skill
Authors: Paisley A M , Baldwin P J , Paterson-Brown S
Published: March 2003

Background

Surgical simulators are being promoted as a means of assessing a surgeon's technical skills. Little evidence exists that simulator performance correlates with actual technical ability. This study was undertaken to determine the criterion and construct validity of currently available surgical simulations in the evaluation of technical skill.

Methods

Simulator assessment was carried out on 36 basic surgical trainees, 37 surgically naïve first-year medical students and 16 experienced general surgical consultants. Some 26 trainees and 36 students underwent repeat assessment after 6 months. A previously validated, 19-point technical skill assessment form, based on direct observation of trainee performance in the operating theatre, was also completed by each trainee's supervising consultant.

Results

An insignificant or weak correlation was found between simulator performance and both duration of basic surgical experience and consultant assessment of technical skill. Six months of basic surgical training led to an improvement in performance, not seen in an untrained control group, in only one of the six simulations tested. Discrimination between surgically naïve and experienced subjects was only demonstrated, in part, for four of the six tasks.

Conclusion

The assessment of technical skill needs to be improved. Work is needed to establish the reliability and validity of currently available simulation models before they are formally introduced for high-stakes assessment.
Multicentre retrospective analysis of the outcome of artificial anal sphincter implantation for severe faecal incontinence
Authors: Altomare D F , Dodi G , La Torre F , Romano G , Melega E , Rinaldi M
Published: March 2003

Background

A new prosthetic device, the ActiconTM artificial anal sphincter, has recently been introduced for treating severe faecal incontinence. The results of this procedure in 28 patients are presented.

Methods

The patients underwent operation for severe faecal incontinence in four Italian university hospitals and patients were reviewed after a median follow-up of 19 (range 7–41) months.

Results

Early infections occurred in four patients, requiring removal of the device in three. Dehiscence of the perineal wound occurred in nine patients. After activation of the device, the cuff had to be removed in a further four patients (for rectal erosion in two, anal pain in one and late infection in one). The cuff was accidentally broken in one patient. A new anal cuff was repositioned successfully in two patients. Overall, five patients had complete removal of the device and two removal of the cuff only. Twenty-one patients available for long-term evaluation had a major improvement in faecal continence. Median resting anal pressure increased from 27 mmHg before surgery to 32 mmHg after operation. Preoperative squeeze pressure was 42 mmHg while maximum postoperative anal pressure with the activated device was 67 mmHg. The median American Medical System incontinence score decreased significantly from 98·5 to 5·5 (P < 0·001). Similar figures were observed using the Continence Grading Scale (from 14·9 to 2·6; P < 0·001). Twelve patients developed symptoms of obstructed defaecation while two patients complained of anal pain.

Conclusion

Improved continence was achieved after neosphincter implantation in three-quarters of the patients. Early infection and rectal erosion, together with difficulty in evacuating, are still major concerns with this technique.
Long-term effects of stapled haemorrhoidectomy on internal anal function and sensitivity
Authors: Altomare D F , Rinaldi M , Sallustio P L , Martino P , De Fazio M , Memeo V
Published: March 2003

Background

Stapled haemorrhoidectomy is gaining wide acceptance but there is still some concern about the risk of injury to the internal anal sphincter (IAS). IAS function and morphology, and anal canal sensitivity were studied prospectively in patients undergoing this operation.

Methods

Twenty patients (11 women; mean age 43 years) with stage III haemorrhoids entered the study. All underwent preoperative anorectal manometry, rectoanal inhibitory reflex (RAIR) testing and three-dimensional transanal ultrasonography. A test of anal sensation was administered to evaluate ability to discriminate between air and warm water. All the investigations were repeated 6 months after the operation.

Results

The mean(s.d.) maximal resting pressure was 87(30) mmHg before surgery and 81(20) mmHg afterwards (P not significant). The maximal squeeze pressure did not change after operation (178(43) versus 174(60) mmHg). The RAIR showed the same features in 19 of 20 patients before and 18 of 20 after operation. Three-dimensional ultrasonography demonstrated no changes in the width of the IAS (mean(s.d.) 2·1(4) mm before and 2·1(3) mm after surgery). The ability of the anal mucosa to discriminate air from warm water improved in five patients. Continence scores did not differ significantly after 6 months.

Conclusion

Stapled haemorrhoidectomy does not affect the function and morphology of the IAS in the long term. The sensitivity of the anal canal can improve in patients with preoperative sensory impairment.
Randomized trial assessing anal sphincter injuries after stapled haemorrhoidectomy
Authors: Ho Y-H , Seow-Choen F , Tsang C , Eu K-W
Published: March 2003

Background

Conventional stapled haemorrhoidectomy involves the use of a large circular anal dilator (DL technique), which may cause anal sphincter injuries. This study compared whether the procedure can be effectively performed without this dilator (ND technique), with better sphincter preservation.

Methods

Fifty-eight patients with symptomatic prolapsed irreducible haemorrhoids were randomized to DL (n = 29) and ND (n = 29) groups. Preoperative continence scoring, anorectal manometry and endoanal ultrasonography were performed. These were repeated at up to 14 weeks after operation, with additional pain scores, analgesic requirements and quality of life assessments.

Results

DL haemorrhoidectomy took significantly longer to perform (P = 0·02). However, there were fewer residual skin tags (P = 0·044) and less perianal pruritis (P = 0·007) at 2 weeks, although such symptoms subsided to an equivalent level in both groups afterwards. Internal anal sphincter fragmentation persisting to at least 14 weeks was found in four patients after DL, but not after ND haemorrhoidectomy (P = 0·038). However, these were asymptomatic and no differences were found in continence scores and anal pressures. The pain scores, satisfaction scores, quality of life assessments and time off work were similar.

Conclusion

The large circular anal dilator used for stapled haemorrhoidectomy increased the risk of anal sphincter injuries, which may become problematic with ageing.
Estimating the benefits of adjuvant systemic therapy for women with early breast cancer
Authors: Grogan M , Tabar L , Chua B , Chen H-H , Boyages J
Published: March 2003

Background

Prognostic factors are commonly used to help identify women with node-negative breast cancer at high risk of recurrence. Although many are available, knowing which risk factor or combination of factors to use to estimate prognosis for an individual woman is often difficult. This study documented the baseline prognoses for a group of women with node-negative breast cancers, and estimated the potential benefits of adjuvant systemic therapy.

Methods

Ten-year, actuarial, cause-specific survival based on tumour size and histological grade using data from the Swedish Two-County Trial of mammographic screening was calculated for 1200 women with node-negative cancers of less than 30 mm diameter. The benefits of adjuvant systemic therapy for these women were then estimated using the published odds reductions in death from adjuvant systemic therapy from the Early Breast Cancer Trialists' Collaborative Group overview.

Results

The absolute 10-year survival benefits for subgroups of women based on tumour size and histological grade were estimated for women aged under 50 years by the addition of chemotherapy, and over 50 years by the addition of tamoxifen and/or chemotherapy.

Conclusion

Decisions about adjuvant systemic therapy in women with node-negative breast cancer need to be individualized, taking into account treatment efficacy and toxicity. The quantitative methods presented in this paper facilitate such decisions.
Ileoanal pouch function is related to postprandial pouch tone
Authors: Steens J , Bemelman W A , Meijerink W J H J , Griffioen G , van Hogezand R A , Masclee A A M
Published: March 2003

Background

Functional impairments are frequently observed in patients with an ileoanal pouch. Meal ingestion increases pouch tone and motility. Little is known, however, about the influence of meal-stimulated pouch characteristics on pouch function. The aim was to characterize basal and postprandial pouch motor and sensory characteristics in relation to clinical pouch function in patients with an ileoanal pouch.

Methods

Nineteen patients with an ileoanal pouch, without faecal incontinence but with either a high stool frequency (n = 8) or an adequate stool frequency (n = 11), underwent pressure distension of the pouch, by which pouch compliance and sensitivity characteristics were assessed using an electronic barostat. A set pressure procedure was performed to assess the influence of a meal on pouch tone and motility.

Results

Mean(s.d.) compliance was 10(6) and 11(4) ml/mmHg in the groups with poor and adequate pouch function respectively (P not significant). Mean(s.d.) visual analogue scale scores (0–10 cm) for urge at the highest pressure of 28 mmHg were 2·3(1·0) versus 2·3(2·4) cm respectively (P not significant); those for pain were 0·8(1·0) versus 0·5(0·7) (P not significant). Postprandially mean(s.d.) pouch volume decreased by 70(24) per cent in the group with poor pouch function and 29(25) per cent in the group with adequate pouch function (P < 0·01). The frequency and amplitude of phasic pouch contractions increased significantly postprandially, but no differences in motility characteristics were observed between the two groups.

Conclusion

In patients with uniform pouch design and follow-up after pouch construction, pouch compliance and sensitivity were no different between patients with normal and high stool frequency; however, postprandial pouch tone was increased significantly in patients with a high stool frequency.
‘Fast track’ postoperative management protocol for patients with high co-morbidity undergoing complex abdominal and pelvic colorectal surgery
Authors: Delaney C P , Fazio V W , Senagore A J , Robinson B , Halverson A L , Remzi F H
Published: March 2003

Background

A combination of factors has emphasized the need to reduce postoperative stay after surgery. Multimodal care plans may shorten hospital stay, but have been associated with high readmission rates and are generally reserved for straightforward, non-complicated colonic (not rectal) resections. This study evaluated a ‘fast track’ protocol in patients undergoing major colonic and rectal surgery.

Methods

Sixty consecutive patients (median age 44·5 (range 13–70) years) underwent major procedures over a 6-week period on one colorectal service. Nasogastric tubes and epidural anaesthesia were not used. Patients participated in a protocol of early diet and early ambulation, and were discharged after meeting defined criteria.

Results

Fifty-eight patients (97 per cent) were deemed suitable for the ‘fast track’ approach at the time of surgery and stayed for a mean(s.d.) of 4·3(1·6) days after operation. Patients in diagnosis-related group (DRG) 148 (colorectal resection with co-morbidity; n = 40) stayed for 4·6(1·7) days, which was longer than those in DRG 149 (without co-morbidity; n = 18) who stayed 3·5(0·8) days (P = 0·01). Three patients (5 per cent) required a nasogastric tube for vomiting. There were no readmissions directly attributable to ‘fast track’ failure, although four patients (7 per cent) were readmitted within 30 days of operation for other reasons. Eight poorly compliant patients stayed for 5·1(1·1) days (P = 0·02 versus compliant patients). ‘Fast track’ patients had a shorter length of stay than patients receiving traditional care on other colorectal services during the same time period (compared by DRG 148, DRG 149 and for all patients) (P < 0·0001).

Conclusion

The ‘fast track’ protocol allows patients with high levels of co-morbidity undergoing complex colorectal and reoperative pelvic surgery to benefit from a rapid recovery and early discharge from hospital. The approach is safe and has low readmission rates.
Immune therapy in inflammatory bowel disease and models of colitis
Authors: Singh B , Powrie F , Mortensen N J McC
Published: March 2003

Background

A proliferation of animal models has not only improved our understanding of inflammatory bowel disease, it has also formed the basis of new treatment strategies.

Methods

A search was conducted using the National Library of Medicine for articles discussing immune therapies for inflammatory bowel disease. This was supplemented by findings from the authors' own laboratory.

Results

An overview of the different animal models is presented. These models are used to highlight the recent human trials of immune therapies. Potential future therapies are also discussed.

Conclusion

Immune therapies have altered the management of patients with inflammatory bowel disease. In future they will influence not only the indications for surgery but also its timing and outcome.
Rising incidence of post-transplant lymphoproliferative disease in kidney transplant recipients
Authors: Libertiny G , Watson C J E , Gray D W R , Welsh K I , Morris P J
Published: March 2003

Background

The purpose of this study was to determine whether the incidence of post-transplant lymphoproliferative disease (PTLD) has been increasing in renal transplant recipients in this centre.

Methods

Prospectively gathered data were analysed to establish trends in the epidemiology of PTLD in 1537 patients.

Results

Overall, PTLD occurred in 2·3 per cent of renal transplant recipients. An increase in its incidence coincided with the introduction of cyclosporin in the 1980s. However, there was a further increase in the incidence of PTLD in the 1990s when the only change in immunosuppressive policy was the abandonment of pretransplantation blood transfusion. The latter increase was particularly pronounced in patients with early-onset PTLD in whom it presented within 600 days after transplantation.

Conclusion

The incidence of PTLD has been increasing in renal transplant recipients. The recent increase appears to be independent of cyclosporin and may reflect the reduction in pretransplant blood transfusion. Changes in the incidence of PTLD may also mirror changes in the epidemiology of non-Hodgkin lymphoma in the general population.
Impact of total mesorectal excision on the results of surgery of distal rectal cancer
Authors: Law W L , Chu K W
Published: March 2003

Background

This study reviewed the results of surgery for distal rectal cancer (tumours within 6 cm of the anal verge) following the introduction of total mesorectal excision for rectal cancer in one institution.

Methods

Two hundred and five patients who had undergone surgical resection of rectal cancer within 6 cm of the anal verge were included. The demographic, operative and follow-up data were collected prospectively. Comparisons were made between patients who had different surgical procedures.

Results

Abdominoperineal resection (APR) was performed in 27·8 per cent of patients, falling from 36·0 per cent in the first 3 years to 20·0 per cent in the last 3 years of the study. The overall operative mortality rate was 1·5 per cent and the morbidity rate 30·2 per cent. With a mean follow-up of 36 months, local recurrence occurred in 28 of the 185 patients who had curative resection. The 5-year actuarial local recurrence rates for double-stapled anastomosis, peranal coloanal anastomosis and APR were 11·2, 34·6 and 23·5 per cent respectively. The local recurrence rate was significantly lower for double-stapled low anterior resection than for the other types of operation. The overall 5-year survival rate in patients with low anterior resection and APR was 69·1 and 51·1 per cent respectively (P = 0·12).

Conclusion

With the practice of total mesorectal excision, APR was necessary in only 27·8 per cent of patients with rectal cancer within 6 cm of the anal verge. The local recurrence rate was much lower in patients with double-stapled low anterior resection than in those treated with APR or peranal anastomosis.
Plasma concentration of tissue inhibitor of matrix metalloproteinase 1 in patients with colorectal carcinoma
Authors: Yukawa N , Yoshikawa T , Akaike M , Sugimasa Y , Takemiya S , Yanoma S , Noguchi Y , Takanashi Y
Published: March 2003

Background

The expression of tissue inhibitor of matrix metalloproteinase (TIMP) 1 in tumour tissue from patients with colorectal carcinoma has been reported to be related to disease progression. However, the clinical significance of plasma TIMP-1 has not been fully elucidated.

Methods

The plasma level of TIMP-1 protein was determined by enzyme-linked immunosorbent assay in samples from 54 patients who underwent resection of the primary tumour.

Results

Plasma TIMP-1 levels were associated significantly with depth of invasion and metastasis to lymph nodes and liver. Circulating TIMP-1 levels were significantly higher in patients with serosal invasion, liver metastases and Dukes' stage C tumours. Using a cut-off value of 160 ng/ml, serosal invasion and Dukes' C stage could be predicted with an accuracy of 68·5 per cent. With a cut-off value of 170 ng/ml, metastasis to the lymph node and liver could be predicted with an accuracy of 66·7 and 70·4 per cent respectively. These values were greater than those for carcinoembryonic antigen and CA19-9.

Conclusion

These data suggest that the plasma concentration of TIMP-1 correlates with both invasion and metastasis in patients with colorectal carcinoma.
Salvage abdominal surgery in patients with a retained rectal stump after restorative proctocolectomy and stapled anastomosis
Authors: Tulchinsky H , McCourtney J S , Rao K V Subba , Chambers W , Williams J , Wilkinson K H , Nicholls R J
Published: March 2003

Background

The introduction of surgical stapling instruments has widened the use of restorative proctocolectomy. Too high a distal transection of the rectum can, however, produce a retained rectal stump, which may cause symptoms. A study of the operative and functional data in a consecutive series of patients undergoing salvage surgery for retained rectal stump was undertaken.

Methods

Twenty-five patients referred between January 1990 and September 2000 for pouch dysfunction were identified as having a retained rectal stump. Twenty-two underwent abdominoanal revision. The hospital notes were reviewed and function was assessed during outpatient visits, by postal questionnaire and by telephone interview.

Results

Median operating time was 225 (range 170–340) min and median hospital stay was 15 (range 8–48) days. There was no operative death. Five pouches were excised. Seventeen patients were available for functional assessment. Median follow-up was 22·5 (range 4–114) months. Median 24-h frequency before and after operation was 12 (range 4–20) and 6 (range 3–12) respectively, and median night-time frequency was 4 (range 0–8) and 0·5 (range 0–4) respectively. Fifteen patients reported marked subjective improvement in pouch function and quality of life.

Conclusion

Major revisional surgery for symptomatic retained rectal stump after restorative proctocolectomy with stapled anastomosis was successful in 15 of 22 patients. These results are worse than the outcome following first-time restorative proctocolectomy with anastomosis constructed at the anal level. Pouch–rectal anastomosis should be avoided.
Prospective analysis of quality of life and survival following mesorectal excision for rectal cancer
Authors: Camilleri-Brennan J , Steele R J C
Published: March 2003

Background

Little is known of how the quality of life of patients with rectal cancer changes after surgery, and whether or not quality of life is associated with and predictive of survival. The aims of this study were to address these issues.

Methods

The Medical Outcomes Study Short Form 36 (SF-36), and the European Organization for the Research and Treatment of Cancer QLQ-C30 and QLQ-CR38 quality of life questionnaires were administered to patients before surgery for rectal cancer, on discharge home and at 3-month intervals after operation for up to 1 year. Survival was measured in days from the time of surgery to death.

Results

Sixty-five patients with a median age of 67 years participated. Most quality of life scores dropped significantly below baseline in the early postoperative period. From the third month onwards some scores, such as the global quality of life score and emotional function score on the QLQ-C30, improved. Other scores, including role function, fatigue and pain on the QLQ-C30, were similar to baseline values after 3–6 months and remained unchanged. However, scores such as sexual enjoyment and male sexual problems on the QLQ-CR38 were worse than baseline in the early postoperative period and remained poor thereafter. Stepwise regression analyses showed that preoperative quality of life dimension scores for physical function, nausea/vomiting and sexual enjoyment, together with age, predicted postoperative 1-year survival with an accuracy of 76·8 per cent.

Conclusion

The findings of this study confirm that quality of life after rectal cancer surgery changes with time. It is generally worst in the early postoperative period. Preoperative quality of life is a good predictor of survival at 1 year.
Randomized clinical trial of patient-controlled versus fixed regimen feeding after elective abdominal surgery
Authors: Han-Geurts I J M , Jeekel J , Tilanus H W , Brouwer K J
Published: March 2003

Background

Although studies have shown that early oral feeding after abdominal surgery is feasible, many surgeons still advocate a careful, slow introduction of postoperative oral feeding. This study was conducted to investigate whether patient-controlled postoperative feeding is possible in patients undergoing colonic or aortic surgery.

Methods

A randomized clinical trial compared patient-controlled postoperative oral feeding (PC group) with a fixed regimen (FR group). Patients in the PC group (n = 56) received oral feeding when they requested it; patients in the FR group (n = 49) started a normal diet on day 5. Endpoints were time to tolerance of a diet similar to the preoperative diet, reinsertion of a nasogastric tube, complications and duration of hospitalization.

Results

Median time to resumption of a normal diet was 3 days in the PC group and 5 days in the FR group (P < 0·001). Reinsertion of a nasogastric tube was required in nine patients in each group (P not significant). The incidence of complications was similar in both groups: 12 of 56 in the PC group and 13 of 49 in the FR group. There was no significant difference in duration of hospital stay between the groups.

Conclusion

Most patients tolerate a normal diet on the third day after operation. Patient-controlled postoperative feeding is safe and leads to earlier resumption of a normal diet.
Randomized clinical trial comparing the efficacy of two bandaging regimens in the treatment of venous leg ulcers
Authors: Meyer F J , Burnand K G , Lagattolla N R F , Eastham D
Published: March 2003

Background

Many venous ulcers are healed by the application of external compression. It has been suggested that bandages capable of producing greater compression enhance healing. The aim of this study was to compare the time to total healing of venous ulcers in two groups of patients treated with different compression regimens in a randomized prospective trial.

Methods

A total of 112 patients was studied and all were treated with a zinc-impregnated paste bandage applied directly to the ulcer. Fifty-seven patients had the paste covered by Tensopress™ and 55 by Elastocrepe™ bandages. Both groups had a tubular bandage applied over the top to retain the bandage in place. All ulcers were stratified and randomized within one of three size groups. The ‘venous’ aetiology of the ulcer was confirmed on completion by calf pump function tests.

Results

By 26 weeks, 58 per cent of the patients treated with Tensopress™ and 62 per cent of those treated with Elastocrepe™ bandages were healed. The median healing times were 9 and 9·5 weeks respectively. Similar numbers of patients were excluded or withdrawn from both groups. Large ulcers healed significantly more slowly than small ulcers.

Conclusion

There was no significant improvement in venous ulcer healing using higher compression elastic bandages.
Risk modelling study for carotid endarterectomy
Authors: Kuhan G , Gardiner E D , Abidia A F , Chetter I C , Renwick P M , Johnson B F , Wilkinson A R , McCollum P T
Published: March 2003

Background

The aims of this study were to identify factors that influence the risk of stroke or death following carotid endarterectomy (CEA) and to develop a model to aid in comparative audit of vascular surgeons and units.

Methods

A series of 839 CEAs performed by four vascular surgeons between 1992 and 1999 was analysed. Multiple logistic regression analysis was used to model the effect of 15 possible risk factors on the 30-day risk of stroke or death. Outcome was compared for four surgeons and two units after adjustment for the significant risk factors.

Results

The overall 30-day stroke or death rate was 3·9 per cent (29 of 741). Heart disease, diabetes and stroke were significant risk factors. The 30-day predicted stroke or death rates increased with increasing risk scores. The observed 30-day stroke or death rate was 3·9 per cent for both vascular units and varied from 3·0 to 4·2 per cent for the four vascular surgeons. Differences in the outcomes between the surgeons and vascular units did not reach statistical significance after risk adjustment.

Conclusion

Diabetes, heart disease and stroke are significant risk factors for stroke or death following CEA. The risk score model identified patients at higher risk and aided in comparative audit.
Multicentre study of detection and false-negative rates in sentinel node biopsy for breast cancer
Authors: Bergkvist L , Frisell J , Liljegren G , Celebioglu F , Damm S , Thörn M
Published: March 2003

Background

Sentinel node biopsy has recently evolved as a means of staging the axilla in breast cancer with minimal surgical trauma. The aim of this prospective multicentre study was to identify factors that influencd the detection and false-negative rates during the learning phase.

Methods

Data on all 498 sentinel node biopsies performed between August 1997 and December 1999 in Sweden were collected.

Results

A sentinel node was found in 450 patients (90 per cent). Preoperative scintigraphy visualized 83 per cent of all sentinel nodes. The detection rate was higher with same-day injection of tracer than with injection the day before (96 versus 86 per cent; P < 0·01). Dye injected less than 5 min or more than 30 min before the start of the operation lowered the detection rate (less than 60 per cent versus more than 65 per cent; P = 0·02). The detection rate varied from 61 to 100 per cent between surgeons. The false-negative rate was 11 per cent. The presence of multiple tumour foci and a high S-phase fraction increased the risk of a false-negative sentinel node, whereas the number of operations performed by each surgeon was less important.

Conclusion

Training of the individual surgeon influenced the detection rate, as did timing of tracer and dye injection. The false-negative rate seemed to be related to biological factors.
Preoperative hepatic venous embolization for partial hepatectomy combined with segmental resection of major hepatic vein
Authors: Ku Y , Tominaga M , Sugimoto T , Iwasaki T , Fukumoto T , Takahashi T , Suzuki Y , Kuroda Y
Published: March 2003

Background

Liver resection of segments VII and/or VIII sometimes requires segmental resection of the right hepatic vein in patients with liver tumours invading or located close to the hepatic vein. In this situation, hepatic vein reconstruction is thought to have an important role in the postoperative function of segment VI. This study investigated whether preoperative embolization of the major hepatic vein could obviate the need for hepatic vein reconstruction after cranial partial resection of the liver including the major hepatic vein trunk in a preclinical model.

Methods

Sixteen beagles were divided into two groups of eight: control group (hepatectomy alone) and hepatic venous embolization (HVE) group (hepatectomy after HVE). HVE was performed 2 weeks before hepatectomy. All dogs underwent resection of the cranial third of the left lateral liver lobe together with the major trunk of the left hepatic vein. Following hepatectomy, survival, histological features, portal venous pressure and serum aspartate aminotransferase (AST) levels were determined.

Results

Six control animals and seven in the HVE group were alive 1 week after hepatectomy. Immediately after hepatectomy, portal venous pressure was significantly higher in the control group compared with the HVE group (mean(s.d.) 14·0(1·1) versus 8·1(1·0) mmHg; P < 0·01). Histological examination of the remnant left lateral lobe demonstrated patchy parenchymal haemorrhage in the control group and normal parenchymal architecture in the HVE group. Peak AST levels were observed on day 1 in both groups and were significantly higher in the control group (mean(s.d.) 182(42) versus 67(40) units/l; P < 0·01).

Conclusion

In this model, preoperative HVE facilitated interlobar venous collateral formation and minimized the untoward effects of segmental hepatic vein resection. This procedure may obviate the need for hepatic vein reconstruction after cranial partial liver resection including the major hepatic vein.
Characterization of the active site of histidine ammonia‐lyase from Pseudomonas putida
Authors: Röther Dagmar , Poppe László , Viergutz Sandra , Langer Birgid , Rétey János
Published: March 2003

Elucidation of the 3D structure of histidine ammonia‐lyase (HAL, EC 4.3.1.3) from Pseudomonas putida by X‐ray crystallography revealed that the electrophilic prosthetic group at the active site is 3,5‐dihydro‐5‐methylidene‐4H‐imidazol‐4‐one (MIO) [Schwede, T.F., Rétey, J., Schulz, G.E. (1999) Biochemistry, 38, 5355–5361]. To evaluate the importance of several amino‐acid residues at the active site for substrate binding and catalysis, we mutated the following amino‐acid codons in the HAL gene: R283, Y53, Y280, E414, Q277, F329, N195 and H83. Kinetic measurements with the overexpressed mutants showed that all mutations resulted in a decrease of catalytic activity. The mutants R283I, R283K and N195A were ≈ 1640, 20 and 1000 times less active, respectively, compared to the single mutant C273A, into which all mutations were introduced. Mutants Y280F, F329A and Q277A exhibited ≈ 55, 100 and 125 times lower activity, respectively. The greatest loss of activity shown was in the HAL mutants Y53F, E414Q, H83L and E414A, the last being more than 20 900‐fold less active than the single mutant C273A, while H83L was 18 000‐fold less active than mutant C273A. We propose that the carboxylate group of E414 plays an important role as a base in catalysis. To investigate a possible participation of active site amino acids in the formation of MIO, we used the chromophore formation upon treatment of HAL with l‐cysteine and dioxygen at pH 10.5 as an indicator. All mutants, except F329A showed the formation of a 338‐nm chromophore arising from a modified MIO group. The UV difference spectra of HAL mutant F329A with the MIO‐free mutant S143A provide evidence for the presence of a MIO group in HAL mutant F329A also. For modelling of the substrate arrangement within the active site and protonation state of MIO, theoretical calculations were performed.
Liberation of the intramolecular interaction as the mechanism of heat‐induced activation of HSP90 molecular chaperone
Authors: Tanaka Etsuko , Nemoto Takayuki K. , Ono Toshio
Published: March 2003

The molecular chaperone function of HSP90 is activated under heat‐stress conditions. In the present study, we investigated the role of the interactions in the heat‐induced activation of HSP90 molecular chaperone. The preceding paper demonstrated two domain–domain interactions of HtpG, an Escherichia coli homologue of mammalian HSP90, i.e. an intra‐molecular interaction between the N‐terminal and middle domains and an intermolecular one between the middle and C‐terminal domains. A bacterial two‐hybrid system revealed that the two interactions also existed in human HSP90α. Partners of the interaction between the N‐terminal and middle domains of human HSP90α could, but those between the middle and C‐terminal domains could not, be replaced by the domains of HtpG. Thus, the interface between the N‐terminal and middle domains is essentially unvaried from bacterial to human members of the HSP90‐family proteins. The citrate synthase‐binding activity of HtpG at an elevated temperature was solely localized in the N‐terminal domain, but HSP90α possessed two sites in the N‐terminal and other domains. The citrate‐synthase‐binding activity of the N‐terminal domain was suppressed by the association of the middle domain. The complex between the N‐terminal and middle domains is labile at elevated temperatures, but the other is stable even at 70 °C. Taken together, we propose the liberation of the N‐terminal client‐binding domain from the middle suppressor domain is involved in the temperature‐dependent activation mechanism of HSP90 molecular chaperone.
Functional expression and characterization of the cytoplasmic aminopeptidase P ofCaenorhabditis elegans
Authors: Laurent Virginie , Brooks Darren R. , Coates David , Isaac R. Elwyn
Published: March 2003

Aminopeptidase P (AP‐P; X‐Pro aminopeptidase; EC 3.4.11.9) cleaves the N‐terminal X‐Pro bond of peptides and occurs in mammals as both cytosolic and plasma membrane forms, encoded by separate genes. In mammals, the plasma membrane AP‐P can function as a kininase, but little is known about the physiological role of the cytosolic enzyme. TheC. elegansgenome contains a single gene encoding AP‐P (W03G9.4), analysis of which predicts regions displaying high levels of amino‐acid sequence homology between the predicted gene product and mammalian cytoplasmic AP‐P, with the absolute conservation of key catalytic residues. The sequence of an EST (yk91g4), comprising the open reading frame of W03G9.4, confirmed the predicted genomic structure of the gene and the prediction thatW03G9.4codes for a nonsecreted protein with a molecular mass of 68 kDa. Nematodes transformed with a promoter reporter construct,W03G9.4::GFP,showed high levels of fluorescence in the intestine of larvae and adult hermaphrodites, indicating that the intestine is a major site ofW03G9.4expression. yk91g4 tagged with a hexahistidine and DLYDDDDK peptide epitope was expressed inEscherichia colito yield, after affinity purification, a recombinant protein with a molecular mass of 71 kDa. The recombinant W03G9.4 removed the N‐terminal amino acid from bradykinin (RPPGFSPFR), aCaenorhabditis elegansneuropeptide (KPSFVRFamide) and Lem Trp 1 (APSGFLGVRamide), but did not display activity towards angiotensin I (NRVYIHPFHL), des‐Arg bradykinin and AF1 (KNEFIRFamide). The activity towards bradykinin was inhibited by EDTA and 1, 10 phenanthroline, as expected for a metalloenzyme, and also by apstatin (IC50, 1 µm), a selective inhibitor of mammalian AP‐P. AKmof 45 µmand an optimum pH of 7–8 was observed with bradykinin as the substrate. The activity of the nematode AP‐P, like its mammalian counterparts, was strongly influenced by metal ions, with Co2+, Mn2+and Zn2+all inhibiting the hydrolysis of bradykinin. We conclude thatW03G9.4codes for a cytoplasmic AP‐P with very similar enzymatic properties to those of mammalian AP‐P, and we suggest that the enzyme has a physiological role in the intracellular hydrolysis of proline‐containing peptides absorbed from the lumen of the intestine.
Rat inositol 1,4,5‐trisphosphate receptor isoform 2 interacts with itself in its C‐terminal portion and upstream of the first transmembrane domain
Authors: Magnino Fabrice , Schmidt Karin , Mery Laurence , Dufour Jean‐François
Published: March 2003

In response to stimulation at the plasma membrane, hepatocellular Ca2+ signals are fast and precise and lead to rapid local changes in cytoplasmic free Ca2+ concentration. These changes result from the opening of the inositol 1,4,5‐trisphosphate receptor (InsP3R), which is a four‐subunit intracellular InsP3‐gated channel that releases Ca2+ from the stores. To investigate the molecular mechanism underlying interactions between the InsP3R subunits, we cloned the predominant hepatocellular isoform, InsP3R isoform 2 (InsP3R2), and screened for interactions using the yeast two‐hybrid assay. We found that the C‐terminal domain of rat InsP3R2 interacts with itself, and that the cytoplasmic part preceding the first transmembrane domain, a region near a Ca2+‐binding site, also interacts with itself. These interactions were confirmed by pull‐down experiments. The C‐terminal domain of InsP3R2 is also able to interact with the C‐termini of rat InsP3R1 and InsP3R3. These results advance our understanding of the molecular mechanisms that underlie the oligomerization and interactions of the InsP3R subunits during the opening/closing of the Ca2+ channel.
Use of site‐specific recombination as a probe of nucleoprotein complex formation in chromatin
Authors: Schwikardi Micha , Dröge Peter
Published: March 2003

DNA transactions in eukaryotes require that proteins gain access to target sequences packaged in chromatin. Further, interactions between distinct nucleoprotein complexes are often required to generate higher‐order structures. Here, we employed two prokaryotic site‐specific recombination systems to investigate how chromatin packaging affects the assembly of nucleoprotein structures of different complexities at more than 30 genomic loci. The dynamic nature of chromatin permitted protein–DNA and DNA–DNA interactions for sites of at least 34 bp in length. However, the assembly of higher‐order nucleoprotein structures on targets spanning 114 bp was impaired. This impediment was maintained over at least 72 h and was not affected by the transcriptional status of chromatin nor by inhibitors of histone deacetylases and topoisomerases. Our findings suggest that nucleosomal linker‐sized DNA segments become accessible within hours for protein binding due to the dynamic nature of chromatin. Longer segments, however, appear refractory for complete occupancy by sequence‐specific DNA‐binding proteins. The results thus also provide an explanation why simple recombination systems such as Cre and Flp are proficient in eukaryotic chromatin.
Bivalent cations and amino‐acid composition contribute to the thermostability of Bacillus licheniformis xylose isomerase
Authors: Vieille Claire , Epting Kevin L. , Kelly Robert M. , Zeikus J. Gregory
Published: March 2003

Comparative analysis of genome sequence data from mesophilic and hyperthermophilic micro‐organisms has revealed a strong bias against specific thermolabile amino‐acid residues (i.e. N and Q) in hyperthermophilic proteins. The N + Q content of class II xylose isomerases (XIs) from mesophiles, moderate thermophiles, and hyperthermophiles was examined. It was found to correlate inversely with the growth temperature of the source organism in all cases examined, except for the previously uncharacterized XI from Bacillus licheniformis DSM13 (BLXI), which had an N + Q content comparable to that of homologs from much more thermophilic sources. To determine whether BLXI behaves as a thermostable enzyme, it was expressed in Escherichia coli, and the thermostability and activity properties of the recombinant enzyme were studied. Indeed, it was optimally active at 70–72 °C, which is significantly higher than the optimal growth temperature (37 °C) of B. licheniformis. The kinetic properties of BLXI, determined at 60 °C with glucose and xylose as substrates, were comparable to those of other class II XIs. The stability of BLXI was dependent on the metallic cation present in its two metal‐binding sites. The enzyme thermostability increased in the order apoenzyme < Mg2+–enzyme < Co2+–enzyme ≈ Mn2+–enzyme, with melting temperatures of 50.3 °C, 53.3 °C, 73.4 °C, and 73.6 °C. BLXI inactivation was first‐order in all conditions examined. The energy of activation for irreversible inactivation was also strongly influenced by the metal present, ranging from 342 kJ·mol−1 (apoenzyme) to 604 kJ·mol−1 (Mg2+–enzyme) to 1166 kJ·mol−1 (Co2+–enzyme). These results suggest that the first irreversible event in BLXI unfolding is the release of one or both of its metals from the active site. Although N + Q content was an indicator of thermostability for class II XIs, this pattern may not hold for other sets of homologous enzymes. In fact, the extremely thermostable α‐amylase from B. licheniformis was found to have an average N + Q content compared with homologous enzymes from a variety of mesophilic and thermophilic sources. Thus, it would appear that protein thermostability is a function of more complex molecular determinants than amino‐acid content alone.
Molecular cloning and characterization of isomultiflorenol synthase, a new triterpene synthase from Luffa cylindrica, involved in biosynthesis of bryonolic acid
Authors: Hayashi Hiroaki , Huang Pengyu , Inoue Kenichiro , Hiraoka Noboru , Ikeshiro Yasumasa , Yazaki Kazufumi , Tanaka Shigeo , Kushiro Tetsuo , Shibuya Masaaki , Ebizuka Yutaka
Published: March 2003

An oxidosqualene cyclase cDNA, LcIMS1, was isolated from cultured cells of Luffa cylindrica Roem. by heterologous hybridization with cDNA of Glycyrrhiza glabraβ‐amyrin synthase. Expression of LcIMS1 in yeast lacking endogenous oxidosqualene cyclase activity resulted in the accumulation of isomultiflorenol, a triterpene. This is consistent with LcIMS1 encoding isomultiflorenol synthase, an oxidosqualene cyclase involved in bryonolic acid biosynthesis in cultured Luffa cells. The deduced amino‐acid sequence of LcIMS1 shows relatively low identity with other triterpene synthases, suggesting that isomultiflorenol synthase should be classified into a new group of triterpene synthases. The levels of isomultiflorenol synthase and cycloartenol synthase mRNAs, which were measured with gene‐specific probes, correlated with the accumulation of bryonolic acid and phytosterols over a growth cycle of the Luffa cell cultures. Isomultiflorenol synthase mRNA was low during the early stages of cell growth and accumulated to relatively high levels in the late stages. Induction of this mRNA preceded accumulation of bryonolic acid. In contrast, cycloartenol synthase mRNA accumulated in the early stages of the culture cycle, whereas phytosterols accumulated at the same relative rate throughout the whole growth cycle. These results suggest independent regulation of these two genes and of the accumulation of bryonolic acid and phytosterols.
Homologous expression and characterization of Cel61A (EG IV) of Trichoderma reesei
Authors: Karlsson Johan , Saloheimo Markku , Siika‐aho Matti , Tenkanen Maija , Penttilä Merja , Tjerneld Folke
Published: March 2003

There are currently four proteins in family 61 of the glycoside hydrolases, from Trichoderma reesei, Agaricus bisporus, Cryptococcus neoformans and Neurospora crassa. The enzymatic activity of these proteins has not been studied thoroughly. We report here the homologous expression and purification of T. reesei Cel61A [previously named endoglucanase (EG) IV]. The enzyme was expressed in high amounts with a histidine tag on the C‐terminus and purified by metal affinity chromatography. This is the first time that a histidine tag has been used as a purification aid in the T. reesei expression system. The enzyme activity was studied on a series of carbohydrate polymers. The only activity exhibited by Cel61A was an endoglucanase activity observed on substrates containing β‐1,4 glycosidic bonds, e.g. carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC) and β‐glucan. The endoglucanase activity on CMC and β‐glucan was determined by viscosity analysis, by measuring the production of reducing ends and by following the degradation of the polymer on a size exclusion chromatography system. The formation of soluble sugars by Cel61A from microcrystalline cellulose (Avicel; Merck), phosphoric acid swollen cellulose (PASC), and CMC were analysed on a HPLC system. Cel61A produced small amounts of oligosaccharides from these substrates. Furthermore, Cel61A showed activity against cellotetraose and cellopentaose. The activity of Cel61A was several orders of magnitude lower compared to Cel7B (previously EG I) of T. reesei on all substrates. One significant difference between Cel61A and Cel7B was that cellotriose was a poor substrate for Cel61A but was readily hydrolysed by Cel7B. The enzyme activity for Cel61A was further studied on a large number of carbohydrate substrates but the enzyme showed no activity towards any of these substrates.
Structural analysis of the lipopolysaccharide from nontypeable Haemophilus influenzae strain 1003
Authors: Månsson Martin , Hood Derek W. , Li Jianjun , Richards James C. , Moxon E. Richard , Schweda Elke K. H.
Published: March 2003

Structural analysis of the lipopolysaccharide (LPS) of nontypeable Haemophilus influenzae strain 1003 has been achieved by the application of high‐field NMR techniques, ESI‐MS, capillary electrophoresis coupled to ESI‐MS, composition and linkage analyses on O‐deacylated LPS␣and core oligosaccharide material. It was found that␣the LPS contains the common structural element of␣H. influenzae, l‐α‐d‐Hepp‐(1→2)‐[PEtn→6]‐l‐α‐d‐Hepp‐(1→3)‐[β‐d‐Glcp‐(1→4)]‐l‐α‐d‐Hepp‐(1→5)‐[PP Etn→4]‐α‐Kdop‐(2→6)‐Lipid A, in which the β‐d‐Glcp residue is substituted by phosphocholine at O‐6 and an acetyl group at O‐4. A second acetyl group is located at O‐3 of the distal heptose residue (HepIII). HepIII is chain elongated at O‐2 by either a β‐d‐Glcp residue (major), lactose or sialyllactose (minor, i.e. α‐Neu5Ac‐(2→3)‐β‐d‐Galp‐(1→4)‐β‐d‐Glcp), where a third minor acetylation site was identified at the glucose residue. Disialylated species were also detected. In addition, a minor substitution of ester‐linked glycine at HepIII and Kdo was observed.
Characterization of a novel silkworm (Bombyx mori) phenol UDP‐glucosyltransferase
Authors: Luque Teresa , Okano Kazuhiro , O'Reilly David R.
Published: March 2003

Sugar conjugation is a major pathway for the inactivation and excretion of both endogenous and exogenous compounds. We report here the molecular cloning and functional characterization of a phenol UDP‐glucosyltransferase (UGT) from the silkworm, Bombyx mori, which was named BmUGT1. The complete cDNA clone is 1.6 kb, and the gene is expressed in several tissues of fifth‐instar larvae, including fat body, midgut, integument, testis, silk gland and haemocytes. The predicted protein comprises 520 amino acids and has ≈ 30% overall amino‐acid identity with other members of the UGT family. The most conserved region of the protein is the C‐terminal half, which has been implicated in binding the UDP‐sugar. BmUGT1 was expressed in insect cells using the baculovirus expression system, and a range of compounds belonging to diverse chemical groups were assessed as potential substrates for the enzyme. The expressed enzyme had a wide substrate specificity, showing activity with flavonoids, coumarins, terpenoids and simple phenols. These results support a role for the enzyme in detoxication processes, such as minimizing the harmful effects of ingested plant allelochemicals. This work represents the first instance where an insect ugt gene has been associated with a specific enzyme activity.