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Biomedical subjects

M C Parker

Publications and source records attributed to M C Parker.

At least 37 records · Page 2Linked to original sources
PubMed2001

Tuning lipase enantioselectivity in organic media using solid-state buffers.

The enantioselectivity exhibited by Candida antarctica lipase B (CALB) in predominantly organic media has been studied for different enzyme protonation states. Alcoholysis of (+/-)-2-phenyl-4-benzyloxazol-5(4H)-one (1) using butan-1-ol as the nucleophile in low-water organic solvents was used as a model reaction. Using either organo-soluble bases or the newly introduced solid-state buffers of known pK(a), the protonation state of the lipase was altered. By choice of the appropriate solid-state buffer or organic base, the enantioselectivity could be selectively tuned. Both Et(3)N and the solid-state buffer pair CAPSO/CAPSO.Na were found to increase the enantioselectivity of the reaction catalyzed by CALB and that of another lipase (Mucor miehei). Significant differences to both the enantioselectivity and catalytic rate were observed, especially under hydrated conditions where byproduct acid was formed.

Buffers↗
PubMed2001

Incomplete large bowel obstruction caused by a duodenal stent.

Gastric outlet obstruction secondary to benign or malignant disease can be treated with self-expanding metallic stents. This obviates the need for surgical bypass procedures and returns most patients to a normal diet. Prosthesis displacement is described as a late complication. A case of stent migration to the rectum, presenting with the symptoms and signs of incomplete large bowel obstruction, is described.

Colonic Diseases↗
PubMed2001

Postoperative adhesions: ten-year follow-up of 12,584 patients undergoing lower abdominal surgery.

PURPOSE: Postoperative adhesions are a significant problem after colorectal surgery. However, the basic epidemiology and clinical burden are unknown. The Surgical and Clinical Adhesions Research Study has investigated the scale of the problem in a population of 5 million. METHODS: Validated data from the Scottish National Health Service Medical Record Linkage Database were used to define a cohort of 12,584 patients undergoing open lower abdominal surgery in 1986. Readmissions for potential adhesion-related disease in the subsequent ten years were analyzed. The methodology was conservative in interpreting adhesion-related disease. RESULTS: In the study cohort 32.6 percent of patients were readmitted a mean of 2.2 times in the subsequent ten years for a potential adhesion-related problem. Although 25.4 percent of readmissions were in the first postoperative year, they continued steadily throughout the study period. After open lower abdominal surgery 7.3 percent (643) of readmissions (8,861) were directly related to adhesions. This varied according to operation site: colon (7.1 percent), rectum (8.8 percent), and small intestine (7.6 percent). The readmission rate was assessed to provide an indicator of relative risk of adhesion-related problems after initial surgery. The overall average rate of readmissions was 70.4 per 100 initial operations, with 5.1 directly related to adhesions. This rose to 116.4 and 116.5, respectively, after colonic or rectal surgery-with 8.2 and 10.3 directly related to adhesions. CONCLUSIONS: There is a high relative risk of adhesion-related problems after open lower abdominal surgery and a correspondingly high workload associated with these readmissions. This is influenced by the initial site of surgery, colon and rectum having both the greatest impact on workload and highest relative risk of directly adhesion-related problems. The study provides sound justification for improved adhesion prevention strategies.

Abdomen↗
PubMed2001

Hot off the press.

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Biological Factors↗
PubMed2000

Measuring enzyme motility in organic media using novel H-D exchange methodology.

A novel deuterium ((2)H) NMR technique as developed for measuring the total number of deuterons exchanged by lyophilised protein samples following hydrogen-deuterium (H-D) exchange. Using this methodology differences in the H-D exchange behaviour of the proteolytic enzyme subtilisin Carlsberg hydrated either in air or an organic solvent were probed as a function of hydration. At low thermodynamic water activity (a(w)), the degree of H-D exchange increased rapidly with hydration (from anhydrous to a(w) 0.22). At a(w) 0.22, subtilisin powders hydrated in air were found to have reached an H-D exchange level comparable to that found upon aqueous dissolution and in agreement with previous studies using lysozyme. Lyophilised subtilisin hydrated in either dichloromethane (DCM) or diisopropyl ether (DIPE) showed a pattern of exchange (vs. a(w)) comparable to that found for powders hydrated in air. However, subtilisin hydrated in n-hexane showed a significant reduction in H-D exchange at all a(w) studied. Control experiments demonstrated that the reduction in H-D exchange observed for subtilisin in n-hexane was not a kinetic effect. This lower level of exchange in n-hexane implies that hydrated subtilisin Carlsberg has a lower conformational motility and more rigid protein matrix.

Air↗
PubMed2000

Hot off the press.

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Antifungal Agents↗
PubMed2000

Hot off the press.

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Biological Factors↗
PubMed2000

Hot off the press.

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Biological Factors↗
PubMed1999

Adhesion-related hospital readmissions after abdominal and pelvic surgery: a retrospective cohort study.

BACKGROUND: Adhesions after abdominal and pelvic surgery are important complications, although their basic epidemiology is unclear. We investigated the frequency of such complications in the general population to provide a basis for the targeting and assessment of new adhesion-prevention measures. METHODS: We used validated data from the Scottish National Health Service medical record linkage database to identify patients undergoing open abdominal or pelvic surgery in 1986, who had no record of such surgery in the preceding 5 years. Patients were followed up for 10 years and subsequent readmissions were reviewed and outcomes classified by the degree of adhesion. We also assessed the rate of adhesion-related admissions in 1994 for the population of 5 million people. FINDINGS: 1209 (5.7%) of all readmissions (21,347) were classified as being directly related to adhesions, with 1169 (3.8%) managed operatively. Overall, 34.6% of the 29,790 patients who underwent open abdominal or pelvic surgery in 1986 were readmitted a mean of 2.1 times over 10 years for a disorder directly or possibly related to adhesions, or for abdominal or pelvic surgery that could be potentially complicated by adhesions. 22.1% of all outcome readmissions occurred in the first year after initial surgery, but readmissions continued steadily throughout the 10-year period. In 1994, 4199 admissions were directly related to adhesions. INTERPRETATION: Postoperative adhesions have important consequences to patients, surgeons, and the health system. Surgical procedures with a high risk of adhesion-related complications need to be identified and adhesion prevention carefully assessed.

Abdomen↗
PubMed1999

Endoluminal stenting of obstructed colorectal tumours.

A series of patients were selected to evaluate the clinical efficacy of a new self expanding metallic endoprosthesis in the management of left-sided colonic obstruction. The aim was to reduce the morbidity and mortality associated with the surgical management of patients with distal colonic obstruction. Six patients with complete sigmoid colon obstruction were managed with the Wallstent Enteral Endoprosthesis [Schneider (USA) Inc.]. Four underwent subsequent elective colonic resection, while two were placed for palliation. Stent placement was successful in all cases with resulting bowel decompression and there were no procedural complications. All four patients with resectable tumours avoided emergency surgery. Stenting allowed time for medical improvement and staging investigations in this group. Two patients with advanced metastatic colonic carcinoma were successfully palliated. We found the Wallstent Enteral Endoprosthesis to be safe and effective in relieving obstruction in patients with resectable colonic tumours, permitting elective surgery and avoiding a temporary stoma. It can also be used to palliate those patients with advanced disease.

Aged↗
PubMed1999

A review of the management of small bowel obstruction. Members of the Surgical and Clinical Adhesions Research Study (SCAR).

Small bowel obstruction is a significant surgical problem and is commonly caused by postoperative adhesions. Patients suffering from this condition are often difficult to assess and require careful evaluation and management. Articles regarding the diagnosis, evaluation and management of small bowel obstruction have been identified from the Ovid, Embase and Silver Platter electronic databases and then reviewed by the authors. Particular emphasis has been placed on randomised controlled trials or large prospective series. Anecdotal reports or those containing small numbers have been largely excluded, but where they have been included it has been made clear in the text. The management of small bowel obstruction is predominantly the management of obstruction due to postoperative adhesions. The selective use of radiological techniques, such as water soluble contrast and CT studies, often help to characterise the nature of the obstruction and may even help with its resolution. Techniques involving the use of laparoscopy and barrier membranes may reduce morbidity but there is a need to evaluate these strategies further with prospective clinical trials.

Humans↗
PubMed1998

Thyroid click.

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Esophageal Perforation↗