Dramatic differences in the binding of UDP-galactose and UDP-glucose to UDP-galactose 4-epimerase from Escherichia coli

UDP-galactose 4-epimerase catalyzes the interconversion of UDP-galactose and UDP-glucose during normal galactose metabolism. Within recent years the enzyme from Escherichia coli has been studied extensively by both biochemical and X-ray crystallographic techniques. One of several key features in the catalytic mechanism of the enzyme involves the putative rotation of a 4'-ketopyranose intermediate within the active site region. The mode of binding of UDP-glucose to epimerase is well understood on the basis of previous high-resolution X-ray crystallographic investigations from this laboratory with an enzyme/NADH/UDP-glucose abortive complex. Attempts to prepare an enzyme/NADH/UDP-galactose abortive complex always failed, however, in that UDP-glucose rather than UDP-galactose was observed binding in the active site. In an effort to prepare an abortive complex with UDP-galactose, a site-directed mutant protein was constructed in which Ser 124 and Tyr 149, known to play critical roles in catalysis, were substituted with alanine and phenylalanine residues, respectively. With this double mutant it was possible to crystallize and solve the three-dimensional structures of reduced epimerase in the presence of UDP-glucose or UDP-galactose to high resolution. This study represents the first direct observation of UDP-galactose binding to epimerase and lends strong structural support for a catalytic mechanism in which there is free rotation of a 4'-ketopyranose intermediate within the active site cleft of the enzyme.     

Cyclosporine dosage can be reduced when used in combination with an anti-intercellular adhesion molecule-1 monoclonal antibody in rats undergoing heterotopic heart transplantation

OBJECTIVE: Although occupationally embedded exercise is becoming a recognized topic in occupational therapy research, study of this phenomenon in children has been limited. The present study examined whether play elicits therapeutic patterns of movement through the use of two ABA single-case experiments. It was predicted that in two children with hypotonic cerebral palsy, the addition of a favorite game to the occupational form, or treatment environment, would increase functional vertical neck and back extension. METHOD: Each subject was positioned in prone on a wedge. During the A phases, each was given verbal directions to hold her head up. During the B phase, a favorite game was introduced. It was predicted that each subject would extend her back and neck in a functional way in order to manipulate and observe the game. The dependent variables were the mean range of neck extension and the mean range of back extension, which were measured by a videotaped, two-dimensional kinematic analysis. RESULTS: The addition of a favorite game to the occupational form improved vertical neck and back extension while discouraging nonfunctional neck hyperextension and fixing postures in both children. CONCLUSION: Embedding exercise within a play occupation enhanced the prone extension of two children with hypotonic cerebral palsy.     

Solar disinfection of drinking water contained in transparent plastic bottles: characterizing the bacterial inactivation process

A series of experiments is reported to identify and characterize the inactivation process in operation when drinking water, heavily contaminated with a Kenyan isolate of Escherichia coli, is stored in transparent plastic bottles that are then exposed to sunlight. The roles of optical and thermal inactivation mechanisms are studied in detail by simulating conditions of optical irradiance, water turbidity and temperature, which were recorded during a series of solar disinfection measurements carried out in the Kenyan Rift Valley. Optical inactivation effects are observed even in highly turbid water (200 ntu) and at low irradiances of only 10 mW cm-2. Thermal inactivation is found to be important only at water temperatures above 45 degrees C, at which point strong synergy between optical and thermal inactivation processes is observed. The results confirm that, where strong sunshine is available, solar disinfection of drinking water is an effective, low cost method for improving water quality and may be of particular use to refugee camps in disaster areas. Strategies for improving bacterial inactivation are discussed.     

Minimally invasive surgery for coronary disease: a new alternative

To avoid the inflammatory syndrome generated by cardiopulmonary bypass, a new surgical technique, minimal invasive direct coronary artery bypass (MIDCAB), has been developed. An anastomosis is performed between the left internal mammary artery (LIMA) and the left anterior descending artery (LAD) on a beating heart, through a limited anterior thoracotomy. We describe our experience with this technique. Ten consecutive patients underwent a MIDCAB procedure. (9 males, age 65.9 +/- 9 years). There were 8 bypasses of the LIMA on the LAD, one bilateral mammary bypass on the LAD and the right coronary artery, and one conversion to a standard sternotomy with CPB for a saphenous vein bypass on the LAD because of injury to the LIMA (2nd case). There was one redo for haemostasis of the mammary artery bed (3rd case). The first 3 patients required postoperative blood transfusion. From the 4th operation onwards, with the introduction of new instrumentation which was better adapted to the narrowness of the surgical field, there were no further surgical complications. During the follow-up (mean 5 months; range 2-9), no patient suffered anginal recurrence. With the improvement of instrumentation, the MIDCAB technique offers satisfactory short- and mid-term results, while avoiding CPB with its adverse effects. Lastly, the cosmetic result is far better than with the conventional procedure.     

Prevalence and management of major risk factors in 500 men with stable coronary disease

In order to achieve an overview of neuroradiology in Europe a questionnaire was sent to all ESNR National Delegates. The answers received were submitted to a data-based analysis, leading to the conclusion that neuroradiology is an expanding discipline among neurological sciences.     

Lipoprotein nature of Bacillus licheniformis membrane penicillinase

Membrane penicillinase (penicillin amido-beta-lactamhydrolase, EC 3.5.2.6) from Bacillus licheniformis bears a striking resemblance to the major outer membrane lipoprotein of Escherichia coli. It can be specifically labeled in vivo with [3H]glycerol, [35S]cysteine, or [3H]palmitate but not by [32P]orthophosphate. The labeled residues are located at or near the NH2 terminus of the membrane penicillinase because they can be completely removed by trypsin which cleaves a hydrophobic peptide(s) from the NH2 terminus, thereby rendering the enzyme hydrophilic. The membrane penicillinase produced by the 749/C gene carried in E. coli on phage lambda is similar to the enzyme formed in strain 749/C itself. The peptide antibiotic globomycin, which prevents processing of the E. coli prolipoprotein, severely inhibited the attachment of [3H]palmitate or [3H]glycerol to the 749/C enzyme (either in B. licheniformis 749/C or in E. coli), blocked the accumulation of penicillinase in the plasma membrane, and enhanced the formation of exoenzyme. Under the same conditions, globomycin does not prevent the attachment of palmitate or glycerol to the E. coli prolipoprotein but inhibits processing of the modified precursor to the mature lipoprotein. These results are in contrast with the lack of effect of globomycin on the RTEM-beta-lactamase of E. coli which has no detectable hydrophobic membrane form and was not labeled with palmitate or glycerol.     

Central nervous system (CNS) involvement in SLE. The diagnostic role of antibodies to neuronal antigens

Dysplasia in inflammatory bowel disease (IBD) is categorized as either flat or associated with a raised lesion or mass (dysplasia-associated lesion or mass [DALM]). One specific subtype of a dysplasia-associated lesion or mass consists of isolated discrete nodules or polyps that are difficult to distinguish from sporadic adenomas. Because the clinical management of these two lesions is different, we performed this study to (1) evaluate the clinical presentation, pathologic features, and natural history of polypoid dysplastic lesions and sporadic adenomas in patients with IBD and (2) determine whether there are clinical, endoscopic, or pathologic findings useful in differentiating between these two lesions. The morphologic features of 89 benign polypoid epithelial neoplasms from 59 patients with IBD (51 with ulcerative colitis, 8 with Crohn's colitis) were evaluated and correlated with the clinical, endoscopic, and follow-up data. In a separate analysis, patients were categorized arbitrarily as having (1) a probable sporadic adenoma if the polypoid epithelial neoplasm was not located within areas of histologically proven colitis, (2) a probable IBD-associated polypoid dysplasia if the lesion developed within an area of colitis, and associated flat dysplasia or an adenocarcinoma was detected during follow-up evaluation or (3) an indeterminate polyp, which was seen in the remainder of the cases. The clinical, endoscopic, and histologic data were compared among these three patient and polyp subgroups. There were 35 males and 24 females (median age, 57 years; range, 27-85 years). Median duration of disease was 10 years. Forty-nine percent of the patients had pancolitis; 66% had histologically active disease at the time of presentation. Nearly 70% of patients had only one polyp; the majority occurred in either the left colon or the rectum (66%). Most polyps were described as a sessile nodule, whereas only 7 (7.8%) were pedunculated. Polyps ranged from 2 mm to 50 mm (median, 5 mm); most had a tubular architecture (84.3%) and contained low-grade dysplasia (64%). In addition, most polyps had mildly increased lamina propria and intraepithelial neutrophilic and mononuclear inflammation. At follow-up evaluation (40 patients; median follow-up time, 13 months; range, 1-78 months), a further neoplastic lesion developed in 20%; low-grade flat dysplasia was seen in 5 (12.5%), and adenocarcinoma developed in 3 (7.5%). However, dysplasia or adenocarcinoma did not develop in the patients who had polyps located outside of areas of histologically proven colitis. In addition, at least one more benign polypoid epithelial neoplasm developed in 15 of 40 patients (37.5%). Patients with probable IBD-associated polypoid dysplasia had a statistically significant (p < 0.05), longer disease duration than patients with probable sporadic adenoma. A statistically significant, higher proportion of polyps with tubullovillous or villous architecture, an admixture of normal and dysplastic epithelium at the surface of the polyps, and increased lamina propria mononuclear inflammation was noted in probable IBD-associated polypoid dysplastic lesions compared with those considered to be sporadic adenomas. Several clinical and pathologic features may be useful to help categorize a polypoid dysplastic lesion as a sporadic adenoma or an IBD-related neoplasm in a patient with IBD. This distinction is important because the natural history of these two lesions (as shown by the results of this study) and their subsequent management are quite different.