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Biomedical subjects

R A Scott

Publications and source records attributed to R A Scott.

At least 91 records · Page 5Linked to original sources
PubMed1995

Transfemoral insertion of a bifurcated endovascular graft for aortic aneurysm repair: the first 22 patients.

The purpose of this study was to evaluate and optimize a system of transfemoral bifurcated graft insertion for endovascular repair of infrarenal aortic aneurysm. Grafts were inserted through bilateral femoral arteriotomies in 22 patients. Placement was guided by fluoroscopy. Results were assessed by completion angiography, with computed tomography scanning or duplex ultrasonography at 1, 3 and 6 months. The first 11 insertions were complicated by failed insertion in two cases, proximal leakage in one, graft limb thrombosis in five and wound infection in one. The second 11 insertions were complicated by retrograde leakage around the distal graft orifice in two patients. One of these was associated with aneurysm rupture, leading to the sole mortality of the series. There were no instances of graft migration or embolism. In conclusion, the lessons learned during the first 11 insertions were responsible for the improved results apparent in the second 11 insertions. When applied in properly selected patients, transfemoral insertion of a bifurcated graft is a reliable method of isolating an aortic aneurysm from the circulation.

Aortic Aneurysm, Abdominal↗
PubMed1995

Gastric outlet obstruction and gastric infarct in junctional epidermolysis bullosa.

A newborn boy had junctional epidermolysis bullosa, duodenal obstruction, and gastric infarction, a newly described combination that extends the spectrum of gastrointestinal findings associated with junctional epidermolysis bullosa. The infant underwent feeding jejunostomy, but died 16 days after birth. This report emphasizes the need for gastrointestinal assessment in any neonate suspected of having epidermolysis bullosa, especially if the pregnancy was complicated by polyhydramnios.

Duodenal Obstruction↗
PubMed1995

Organizational aspects of caring.

Caring is fundamental to competence in medicine. Expressions of humaneness in the relationship between doctor and patient foster bonds of trust, enabling doctors and patients to communicate in ways that enhance diagnosis, treatment, and compliance. To be effective, a caring attitude must be adopted by all persons involved in the delivery of health care. Components of caring can be specified, learned, and incorporated into routine medical practice. Through their impact on stress management and coping, as well as morale and job satisfaction, the organizational and administrative practices surrounding health care encounters decisively impinge on caring. The organizational and financial arrangements for enhancing the humane delivery of health care are examined.

Attitude of Health Personnel↗
PubMed1995

Peribulbar anaesthesia and needle length.

This retrospective audit of 87 consecutive patients undergoing routine cataract surgery compared the effect of peribulbar local anaesthesia using 16 mm and 25 mm, 25 gauge needles to administer the anaesthetic. The effect on optic nerve function was observed. There was a significant increase of complete amaurosis in the group where the 16 mm needle had been used. This may be explained by more effective anatomic placement of the 16 mm needle within the orbit, allowing access to the retrobulbar space via fascial septae. There was significantly more lid akinesia with the 16 mm needle. None of this group required an additional facial nerve block, as opposed to 14% of the 25 mm needle group. The use of a 16 mm needle is theoretically safer than a 25 mm needle to administer a peribulbar anaesthetic, in this review it was also demonstrated to be more effective.

Aged↗
PubMed1994

Surgical workload as a consequence of screening for abdominal aortic aneurysm.

A study was performed to evaluate the surgical workload that has resulted from screening an at-risk population for abdominal aortic aneurysm (AAA) and to forecast the likely workload from an established screening programme. Over an 8-year period 8944 people aged 65-80 years were screened; 356 were found to have an AAA of 3 cm or greater in diameter. There were 288 outpatient consultations involving 171 patients, and 43 patients (4.8 per 1000 screened) had surgery during the study period. A fully operational screening programme for a population of 250,000, screening men and women at a rate of 2000 per year, would be expected to produce a surgical workload of nine or ten operations for AAA per year. Screening men only would increase this to 34 annually.

Aged↗
PubMed1994

Accuracy of ultrasound in a screening programme for abdominal aortic aneurysms.

OBJECTIVES: To assess the accuracy of ultrasound in the measurement of aortic diameter. SETTING: A general practice based screening programme for abdominal aortic aneurysm. DESIGN: (a) comparison of ultrasound with computed tomography (CT) measurement; (b) two period crossover study to assess interobserver error; (c) comparison of ultrasound measurements by technicians and radiologists. RESULTS: In 36 patients where CT showed clear maxima in anteroposterior diameter, the measurement by ultrasound was consistently less than by CT scan (mean ultrasound-CT difference -4.4 mm, range -12.3 to 2.4 mm). There was no difference in the measurements made by different ultrasonographers, but their method of measurement produced a reading for aortic diameter less than that obtained by a vascular radiologist. CONCLUSIONS: These results show that ultrasound measurement is less accurate for smaller aneurysms, consistently gives a smaller reading for aortic diameter when compared with CT measurement, but was reproducible between ultrasonographers. Monitoring and audit of aneurysm screening programmes to assess accuracy and reproducibility of ultrasound measurement is recommended.

Aged↗
PubMed1994

Is screening once at age 65 an effective method for detection of abdominal aortic aneurysms?

OBJECTIVE: To evaluate whether a single screening at 65 or screening at 65 and 70 are the methods of choice to detect the majority of abdominal aortic aneurysms (AAA) suitable for treatment. SETTING: District general hospital, district general practice and community. METHODS: Data were collated from four studies (a pilot, a control trial, and two cohorts) of abdominal ultrasound screening of an invited group of 11 666 men and women aged 65-80 to derive age related prevalence, invitation acceptance rates, and operative mortality. Deaths from AAA rupture were obtained from district registrars' returns. RESULTS: The prevalence of AAA increased with age being greater overall in men (6.8%) than in women (1.2%). From ages 65 to 80 the prevalence in men increased from 5.4% to 10.4%, and in women from 0.6% to 2.1%. In men and women 4% of patients dying from AAA rupture were aged 65 or under and 85% of deaths occurred over the age of 70. Acceptance rates for screening decreased between 65 and 80 from 80.5% to 66.2% in men and from 72.7% to 58.3% in women. In elective or symptomatic patients operative mortality was zero up to the age of 70, increasing to 7.1% in older patients. CONCLUSIONS: Men should be screened at age 65 to obtain a high acceptance rate and to identify those with AAA most likely to benefit from treatment. The prevalence is relatively low at this age so an additional screen at age 70 is recommended, which would pick up a further 3.7% of patients with AAA, at which age intervention is likely to be of benefit.

Age Factors↗
PubMed1993

Is surgery necessary for abdominal aortic aneurysm less than 6 cm in diameter?

During 8 years of an ultrasound screening programme for abdominal aortic aneurysm (AAA), 8944 people aged 65-80 years were scanned. 356 (4%) had AAA of diameter 3 cm or greater. Under our criteria repair was indicated if the aortic diameter reached 6 cm, if expansion reached 1 cm per year, or if the AAA caused symptoms; 124 patients met these criteria. Among the 8820 screened patients who did not meet the criteria, 1 death (0.4%) was attributed to ruptured aneurysm, although the retroperitoneal haematoma had developed within 5 days of surgery for a colon tumour. The risk of aortic rupture in patients with AAA less than 6 cm diameter with these criteria (0.4%) is lower than that for elective surgery (1-8%). Surgical repair is unnecessary and possibly detrimental in such patients, provided that ultrasound surveillance is undertaken.

Aged↗
PubMed1993

Nature of the low activity of S-methyl-coenzyme M reductase as determined by active site titrations.

Purified S-methyl-coenzyme M reductase (methylreductase) exhibits a very low fraction of its in vivo activity, suggesting either enzyme inactivation during cell lysis and chromatographic purification or the lack of an activating component in assay mixtures. Evidence that all methylreductase molecules in the purified protein can catalyze slow substrate turnover is found in a study of turnover-dependent in vitro incorporation of radiolabeled HS-CoM at the enzyme active site (Hartzell, P. L., Donnelly, M. I., and Wolfe, R. S. (1987) J. Biol. Chem. 262, 5581-5586). We have conducted active site titrations of purified methylreductase and of a highly active partially purified preparation (Rospert, S., Bocher, R., Albracht, S. P. J., and Thauer, R. K. (1991) FEBS Lett. 291, 371-375) using the reversible competitive inhibitor bromopropanesulfonate (K(i) = 0.05 microM). Curve fitting the data based on an equilibrium binding model shows that 0.1-1.4% of purified methylreductase has functional inhibitor binding sites while up to 25% of a highly active preparation binds the inhibitor. An EPR titration of highly active methylreductase with this inhibitor is consistent with this result, showing that the MCR-red1 and -red2 EPR signals (Albracht, S. P. J., Ankel-Fuchs, D., Bocher, R., Ellermann, J., Moll, J., van der Zwann, J. W., and Thauer, R. K. (1988) Biochim. Biophys. Acta 955, 86-102) are titrated in parallel with this active fraction. Attempts to observe turnover-dependent uptake of radiolabel from [thio-35S]2-methylthioethane-sulfonate by methylreductase were unsuccessful. These results suggest that the low activity of purified methylreductase is due primarily to low percentages of catalytically competent enzyme.

Alkanesulfonates↗
PubMed1993

Purification and characterization of Klebsiella aerogenes UreE protein: a nickel-binding protein that functions in urease metallocenter assembly.

The Klebsiella aerogenes ureE gene product was previously shown to facilitate assembly of the urease metallocenter (Lee, M.H., et al., 1992, J. Bacteriol. 174, 4324-4330). UreE protein has now been purified and characterized. Although it behaves as a soluble protein, UreE is predicted to possess an amphipathic beta-strand and exhibits unusually tight binding to phenyl-Sepharose resin. Immunogold electron microscopic studies confirm that UreE is a cytoplasmic protein. Each dimeric UreE molecule (M(r) = 35,000) binds 6.05 + 0.25 nickel ions (Kd of 9.6 +/- 1.3 microM) with high specificity according to equilibrium dialysis measurements. The nickel site in UreE was probed by X-ray absorption and variable-temperature magnetic circular dichroism spectroscopies. The data are most consistent with the presence of Ni(II) in pseudo-octahedral geometry with 3-5 histidyl imidazole ligands. The remaining ligands are nitrogen or oxygen donors. UreE apoprotein has been crystallized and analyzed by X-ray diffraction methods. Addition of nickel ion to apoprotein crystals leads to the development of fractures, consistent with a conformational change upon binding nickel ion. We hypothesize that UreE binds intracellular nickel ion and functions as a nickel donor during metallocenter assembly into the urease apoprotein.

Amino Acid Sequence↗
PubMed1993

Leucocyte count: a predictor of early femoropopliteal graft failure.

The patency of 90 elective femoropopliteal reconstructions was assessed 6 months after surgery. The preoperative white cell count was found to be a highly significant predictor of early graft failure (P < 0.0001) independent of other previously recognized predictors of occlusion such as smoking and run-off.

Aged↗
PubMed1992

X-ray absorption spectroscopic studies of the high-spin iron(II) active site of isopenicillin N synthase: evidence for Fe-S interaction in the enzyme-substrate complex.

Isopenicillin N synthase from Cephalosporium acremonium (IPNS; M(r) 38.4K) is an Fe(2+)-requiring enzyme which catalyzes the oxidative conversion of (L-alpha-amino-delta-adipoyl)-L-cysteinyl-D-valine (ACV) to isopenicillin N, with concomitant reduction of O2 to 2H2O. Chemical and spectroscopic data have suggested that catalysis proceeds via an enzyme complex of ACV bound to the iron through its cysteinyl thiolate [Baldwin, J. E., & Abraham, E. P. (1988) Nat. Prod. Rep. 5, 129-145; Chen, V. J., Orville, A. M., Harpel, M. R., Frolik, C. A., Surerus, K. K., Münck, E., & Lipscomb, J. D. (1989) J. Biol. Chem. 264, 21677-21681; Ming, L.-J., Que, L., Jr., Kriauciunas, A., Frolik, C. A., & Chen, V. J. (1991) Biochemistry 30, 11653-11659]. Here we have employed the technique of Fe K-edge extended X-ray absorption fine structure (EXAFS) to characterize the iron site and to seek direct evidence for or against the formation of an Fe-S interaction upon ACV binding. Our data collected in the absence of substrate and O2 are consistent with the iron center of IPNS being coordinated by only (N,O)-containing ligands in an approximately octahedral arrangement and with an average Fe-(N,O) distance of 2.15 +/- 0.02 A. Upon anaerobic binding of ACV, the iron coordination environment changes considerably, and the associated Fe EXAFS cannot be adequately simulated without incorporating an Fe-S interaction at 2.34 +/- 0.02 A along with four or five Fe-(N,O) interactions at 2.15 +/- 0.02 A.(ABSTRACT TRUNCATED AT 250 WORDS)

Acremonium↗
PubMed1992

Spectroscopic characterization of the alternate form of S-methylcoenzyme M reductase from Methanobacterium thermoautotrophicum (strain delta H).

Two forms (MR1 and MR2) of S-methylcoenzyme M reductase were purified from Methanobacterium thermoautotrophicum (strain delta H) as recently described (Rospert, S., Linder, D., Ellerman, J. and Thauer, R.K. (1990) Eur. J. Biochem. 194, 871-877). MR2 was at least 50-fold more active than MR1, independent of assay conditions. The two forms are spectroscopically similar, but not identical, by UV-visible, magnetic circular dichroism and resonance Raman spectroscopies. MR2 exhibited an EPR signal corresponding to 20% of the enzyme-bound nickel. Strong EPR signals similar to those previously assigned to Ni(I)F430 bound to methylreductase in Methanobacterium thermoautotrophicum (strain Marburg) (Albracht, S.P.J., Ankel-Fuchs, D., Bocher, R., Ellerman, J., Moll, J., Van der Zwann, J.W. and Thauer, R.K. (1988) Biochim. Biophys. Acta 955, 86-102) were observed in MR2-rich, log-phase, as well as in MR1-rich, slow-growing bacteria. Log-phase cells had dramatically different EPR spectra depending on whether they were removed from the fermenter (under gas flow) before or after cooling to 10 degrees C. EPR spectra of slow-growing cells were insensitive to harvesting conditions. The possible biological significance of the alternate form of methylreductase is discussed.

Circular Dichroism↗