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E Sim

Publications and source records attributed to E Sim.

At least 73 records · Page 4Linked to original sources
PubMed1994

Chromosomal localization of human genes for arylamine N-acetyltransferase.

Arylamine N-acetyltransferase is encoded at two loci, AAC-1 and AAC-2, on human chromosome 8. The products of the two loci are able to catalyse N-acetylation of arylamine carcinogens, such as benzidine and other xenobiotics. AAC-2 is polymorphic and individuals carrying the slow-acetylator phenotype are more susceptible to benzidine-induced bladder cancer. We have identified yeast artificial chromosome clones encoding AAC-1 and AAC-2 and have used the cloned DNAs as fluorescent probes for in situ hybridization. The hybridization patterns allow assignment of AAC-1 and AAC-2 to chromosome 8p21.3-23.1, a region in which deletions have been associated with bladder cancer [Knowles, Shaw and Proctor (1993) Oncogene 8, 1357-1364].

Arylamine N-Acetyltransferase↗
PubMed1994

[Intraoperative irrigation of the subdural space after traumatic spinal cord lesions (based on 4 case examples)].

In experimental investigations on primates it has been shown that after a standardized transverse lesion of the spinal cord subdural perfusion with an artificial liquor solution (Elliot's B solution) of the region of the injury improved the eventual motoric function achieved. We tried to reproduce these experimental results in the management of four patients with acute spinal cord injury after trauma of the vertebral column. Due to the difficulty of an exact evaluation in this initial study an objective positive effect of perfusion with Ringer solution (at 37 degrees C) could not be confirmed in these patients. Nevertheless, the possibility of a positive influence of this adjuvant operative treatment on spinal cord injuries should be studied in a greater collective of patients. A multicentre study would be essential because of the limited number of cases in a single hospital.

Adult↗
PubMed1994

Transcondylar reinsertion of femoral avulsions of the anterior cruciate ligament: evaluation of the position in 20 cases using three-dimensional computed tomographic reconstruction.

The position of transcondylar small-caliber drill tunnels after reinsertion of femoral avulsions of the anterior cruciate ligament (ACL) including avulsions with bone or cartilage fragments, which escape objective verification by conventional roentogenography, was determined in 20 patients by an examination procedure using computed tomography. Coronary tomograms were used for three-dimensional reconstruction of the distal end of the femur and assessment of the position of the perforation sites in the area of the medial aspect of the lateral condyle as well as the distance between them in patients in whom two Kirschner wires had been used (16 patients). A correct position had been achieved only in 4 of the 16 cases with double reinsertion and in one of four cases in which a single Kirschner wire had been used. With exception of one only partially correct placement, localization was found ventrally from the transition line with a predominantly caudally directed component. Assuming a mean thickness of the anterior cruciate ligament of 5 mm, the distance of the drill tunnels in five cases met the anatomic requirements, was too small in six cases, too large in three cases, and could not be evaluated adequately in two cases. The results of the present study illustrate vividly the problems of the surgical technique of Palmer.

Adolescent↗
PubMed1994

Patency of internal thoracic artery grafts: comparison of right versus left and importance of vessel grafted.

BACKGROUND: The early and late patency of the left internal thoracic artery (LITA) has been studied thoroughly, but less is known about coronary artery bypass grafts constructed from the right internal thoracic artery (RITA). METHODS AND RESULTS: Between January 1984 and March 1991, 413 patients on two surgical services had bilateral arteries or RITAs used as conduits for coronary artery revascularization. Sixty-seven patients (16%; 57 male and 10 female; mean age, 59 years) had graft angiography performed up to 97 months after operation (average, 27 months). In 38 patients, angiography was performed because of angina or other objective evidence of myocardial ischemia. For all 67 patients evaluated, patency of RITA grafts was 86% (58/67), and patency of LITA grafts was 89% (57/64). For grafts to the left anterior descending (LAD) coronary artery, overall patency was 90% (58/64), and there was little difference in patency of the RITA (93%, 28/30) versus the LITA (88%, 30/34). In contrast, the overall patency rate for internal thoracic arteries used to bypass vessels other than the LAD was 76% (45/59, P < .03 versus LAD); for these bypasses to arteries other than the LAD, RITA patency was 74% (26/35), and the patency of LITA grafts was 79% (19/24). Patency of RITA grafts routed through the transverse sinus was similar to patency of other bypasses to non-LAD vessels. Among 12 free grafts that used segments of the RITA, 10 were patent (83%). Of additional saphenous vein grafts, 69% (39/56) were patent at restudy. CONCLUSIONS: This study supports the continued use of the RITA as a conduit for coronary artery revascularization. In our experience, the position of the target vessel is a more important determinant of graft patency than the side of the internal thoracic artery selected for use as a bypass graft.

Coronary Angiography↗
PubMed1993

Arylamine N-acetyltransferase activity in human cultured cell lines.

Many arylamine and hydrazine drugs and xenobiotics are acetylated by liver N-acetyltransferase (NAT; EC 2.3.1.5). Two loci, mnat and pnat, encode the enzymes designated monomorphic and polymorphic NAT (mNAT and pNAT) respectively. These isoenzymes have different substrate specificities. In addition, at the polymorphic locus a diversity of alleles is found, which differ by specific point mutations that may or may not result in amino acid substitutions. These point mutations result in the 'slow' acetylation of substrates of pNAT. The substrates for NAT include carcinogenic arylamines. Susceptibility to bladder cancer has been related to slow acetylation. NAT has been characterized in immortalized human cell lines to assess their use in studies of the metabolism or arylamines in vitro. A monocytic cell line (U937) and two hepatoma cell lines of parenchymal lineage (HepG2 and Hep3B) have been shown to catalyse acetylation of substrates of mNAT but do not acetylate sulphamethazine, a substrate specific for pNAT. Using PCR to amplify the alleles of pNAT, followed by restriction-enzyme digestion of the product, the cell lines have been genotyped: U937 cells are homozygous slow acetylators (S1a/S1a) and HepG2 cells are heterozygous slow acetylators (S1a/S2). Transcription of pnat was confirmed in the hepatoma cell lines, by amplification of cDNA generated from these cells. In addition, splicing of mRNA specific for pNAT has been demonstrated by using a primer which anneals to a region in the 5' promoter region. Unlike the hepatoma cell lines, in U937 cells the pNAT gene is not transcribed. However, transcription of mnat was shown to occur in all three cell lines.

Acetylation↗
PubMed1993

Effect of thiol compounds on human complement component C4.

Thiol compounds have been investigated as inhibitors of the covalent binding reaction of human complement protein C4 using Sepharose-C1s as a combined activating and binding surface. o- and p-substituted aminothiophenols are equally effective inhibitors, whereas the m-substituted compound is a less potent inhibitor. The anti-hypertensive drug captopril is also shown to inhibit the covalent binding reaction. A comparison of the effects of these compounds on the covalent binding reaction of isolated C4A and C4B has been made. Results suggest that a Pro-to-Leu substitution in C4B is likely to account for the differences in inhibitory potency of C4B compared with C4A observed with the aromatic inhibitors.

Aminophenols↗
PubMed1993

The interaction of soluble human complement receptor type 1 (sCR1, BRL55730) with human complement component C4.

Human CR1 is a membrane-bound protein which plays an important role in the control of the human complement system. In addition to its involvement in the processing and clearance of immune complexes with C3b or C4b on their surface, CR1 acts as a cofactor for the proteolysis of C3b and C4b by Factor I. sCR1 is a recombinant, soluble form of CR1 which retains the cofactor activities of CR1, and is of potential therapeutic value for the suppression of complement-mediated tissue damage in vivo. An assay has been established using microtitre plates to explore the binding of sCR1 to the two isotypes of C4, C4A and C4B, and to C4 fragments. Specific binding of 125I-sCR1 to C4b and ammonia-treated C4 has been demonstrated. The binding of 125I-sCR1 to ammonia-treated C4 is dependent on pH and ionic strength, decreasing with an increase in pH and with an increase in ionic strength. At physiological ionic strength, up to twice as much 125I-sCR1 bound to ammonia-treated C4A as bound to ammonia-treated C4B. This preference of sCR1 for binding to the C4A isotype has implications for the clinical association of immune complex disease with C4A null alleles.

Ammonia↗
PubMed1993

Location of transpedicular screws for fixation of the lower thoracic and lumbar spine. Computed tomography of 45 fracture cases.

Postoperative CT examinations of an unselected group of 45 patients with fractures of the thoracolumbar and lumbar spine including 1 patient with traumatically activated spondylolisthesis were analyzed for the location of the 200 screws, the angles of insertion, and the screw vs pedicle diameters. In all cases transpedicular systems had been used for fixation, i.e., the AO-Fixateur Interne in 28 patients, a combination of Teinturier plates and USI screws in 11 patients, and the VSP system in 7 patients. Using a standardized surgical technique and image intensification in 2 planes throughout, 92 percent of all pedicles were instrumented with acceptable deviations from the anatomic axes. Mismatches between the pedicle and the screw diameters were found in 3 instances, and 2 screws were placed in the transverse processes only. Canal encroachment in 13 patients did not impede neural structures. Slight perforation of the anterior cortex of the vertebral body was recorded in 3 percent of cases, but did not cause any complications.

Bone Screws↗
PubMed1993

Color-coded Duplex sonography of vertebral arteries. 11 cases of blunt cervical spine injury.

In 11 patients with locked cervical spine facets after blunt injury, the patency of the vertebral arteries was evaluated by color-coded Duplex sonography (CCDS) up to 11 years after the accident. In 7 patients the dislocations had been reduced, 2 had been treated conservatively, and 9 had been fused. In 9 patients (3 of them with persistent locking) the mean systolic peak flow velocity was 55 cm/sec and the vessel diameter was 0.35 cm. Only 2 patients had an abnormal CCDS. In 1 with persistent locking the ipsilateral vertebral artery was occluded, and in the other flow signals were abnormal and the vessel diameter was smaller than on the contralateral side. The high coincidence of vertebral artery occlusions and locked dislocations, as well as fracture dislocations reported by others, was not confirmed in our series.

Adolescent↗
PubMed1993

[Choice of femoral reinsertion sites after rupture of the anterior cruciate ligament--a roentgenologic evaluation model].

The position of transcondylar small caliber drill tunnels after reattaching of femoral avulsions of the anterior cruciate ligament usually escapes objective verification by conventional roentgenography. A model of investigation and the results of cadaver studies are presented: Stored CT data are used for 3D-reconstruction of the distal end of the femur. In such manner the sites of perforation of the K wires can be determined unequivocally and distinctly.

Anterior Cruciate Ligament↗
PubMed1993

[Unilateral locking of cervical facet joints. Frequency and value of roentgenologic signs].

Unilateral locking of cervical facet joints is often misdiagnosed and inadequately treated, because it is not readily detected on plain radiographs. Primary radiographs of 17 patients were analysed to evaluate radiographical signs with reference to frequency and significance. Direct signs of locking were present in no more than 53% of cases. Of these, an abrupt change in laminar space width, seen in 88.2%, proved to be the most reliable sign. Displacement of the spinous processes above and below the lesion was found in the same percentage of cases, but it carries less diagnostic weight. While present in all cases, anterolisthesis is only diagnostic if additional oblique views show evidence of lateralized cervical anterolisthesis. Clearly less reliable indirect signs included: the bow tie sign (29.4%), dehiscence of the spinous processes (23.5%), differences in the sagittal diameters of the vertebral bodies above and below the lesion (35.2%), double facet contour (47%) and tilting of the cranial segment of the cervical spine away from the locked facets (58.8%). Abnormalities of disc shape were not seen on a.-p. projections. Those detectable in axial views are irrelevant to locking, as are empty facets. If more than one indirect sign is present and if unilateral locking is suspected but cannot be established unequivocally even on additional oblique views, computed tomography is indicated, because reduction continues to be the first step in the management of fresh injuries.

Adolescent↗
PubMed1993

Changing patterns in the treatment of early breast cancer: a historical perspective and a review of changing local trends.

Over the past 50 years, a variety of surgical procedures have been advocated for the treatment of operable breast cancer, ranging from local excision to supraradical mastectomy. Today, the surgical treatment of breast cancer remains highly contentious. We review the historical development of breast cancer surgery and analyse the available evidence supporting conservative procedures. We also express our opinions on the treatment of early breast cancer and illustrate the changing patterns of surgery with our experience at National University Hospital.

Breast Neoplasms↗
PubMed1992

Arylamine N-acetyltransferase in human red blood cells.

N-Acetyltransferase activities associated with erythrocytes from 20 individuals have been determined with p-aminobenzoic acid as substrate. A three-fold variation in Vmax is found. The N-acetyltransferase genotype of the individuals has been determined and there is no correlation between the extent of acetylation measured in the individuals' erythrocytes and the inheritance of alleles at the polymorphic NAT locus. Folate is confirmed to be an inhibitor of arylamine N-acetyltransferase activity measured in erythrocytes. The content of folate in erythrocytes of individuals also varies. The individual with the maximum folate content has the minimum N-acetyltransferase activity. The monomorphic N-acetyltransferase gene from individuals spanning the range of N-acetyltransferase activity have been amplified, using the polymerase chain reaction. The pattern of restriction enzyme digestion of the monomorphic N-acetyltransferase gene with a series of eight restriction enzymes is the same for individuals spanning the activity range of arylamine N-acetyltransferase in their erythrocytes.

4-Aminobenzoic Acid↗
PubMed1992

The fixateur interne for stabilising fractures of the thoracolumbar and lumbar spine.

Between 1986 and 1988, 27 patients with fractures of the thoracolumbar and lumbar spine were treated by fixateur interne (FI) instrumentation, and 24 were followed up for a mean of 25 months. Complications occurred in 13 cases, mostly due to loosening and corrosion. The results were compared with plate fixation. The radiological parameters and differences between the preoperative and postoperative indices were well within the normal range. The inferiority of FI instrumentation compared to plate fixation during follow up was mainly attributable to the complications. Reduction of the posterior wall fragments by the intact posterior longitudinal ligament was not consistent, so instrumented reduction is usually the method of choice.

Adolescent↗
PubMed1992

Surgical management of right colon diverticulitis.

The infrequent occurrence of right colon diverticulitis in the developed West has led to a controversy in the management of this disease. In Singapore, we continued to avoid colectomy whenever possible because this disease is usually nonprogressive. We reviewed 68 patients treated by conservative surgery to evaluate the effectiveness of this treatment policy. Almost 70 percent of our patients were below 40 years of age, and the clinical presentation was indistinguishable from acute appendicitis. Diverticulectomy was done only for inflamed and perforated diverticula (25 cases), while the nonperforated diverticulum was left alone (40 cases). The inflammation invariably responded to antibiotic therapy. Only three patients had colonic resection since a malignant neoplasm could not be excluded. There were no adverse sequelae over a mean follow-up period of three and one-half years, except for one patient who had recurrent attacks of right colon diverticulitis necessitating colectomy. With this policy of management we encountered no mortality, and morbidity was acceptable.

Adult↗