PubMed Health⌕ Search

Biomedical subjects

R B Trimble

Publications and source records attributed to R B Trimble.

At least 19 recordsLinked to original sources
PubMed1995

Spontaneous recovery rates for unilateral sixth nerve palsies.

Two hundred and thirteen patients with unilateral isolated sixth nerve palsies were assessed to determine what proportion of them underwent spontaneous recovery and over what period of time this recovery occurred. All were primary ophthalmic referrals from which trauma was excluded. In all, 78.4% of patients experienced spontaneous recovery of their palsy, 36.6% recovering by 8 weeks and 73.7% by 24 weeks. Only 16.4% failed to recover. Of this group, however, nearly 40% had serious underlying pathology accounting for their palsy.

Abducens Nerve↗
PubMed1994

Clinical experience with a fixed dose combination therapy of timolol and pilocarpine used twice daily in the management of chronic open angle glaucoma.

Twenty-five eyes of 25 patients with primary chronic open angle glaucoma deemed controlled for 12 months were converted from timolol 0.25% or 0.5% b.d. and pilocarpine 2% q.i.d. to a combination drop (TP2) of combined timolol 0.5% and pilocarpine 2% given b.d. Mean intraocular pressures (IOP) were 18.68 +/- 2.84 mmHg at 1 month, 18.81 +/- 2.56 mmHg at 3 months and 18.56 +/- 2.01 mmHg at 6 months. These values were significantly higher than the initial IOP of 17.48 +/- 2.2 mmHg (p values 0.0006, 0.0001 and 0.0004 respectively). However, 1 month following reconversion to initial therapy the IOP was 17.68 +/- 2.67 mmHg, which was not significantly higher than the initial IOP (p = 0.46). In addition, of 8 eyes uncontrolled during the course of the study, 6 became controlled following reconversion to initial treatment. Combination therapy of TP2 b.d. cannot be recommended to control IOP satisfactorily in patients maintained on timolol 0.25% or 0.5% b.d. and pilocarpine 2% q.i.d.

Aged↗
PubMed1992

Structural heterogeneity in the Man8-13GlcNAc oligosaccharides from log-phase Saccharomyces yeast: a one- and two-dimensional 1H NMR spectroscopic study.

Previously, Man8-14GlcNAc oligosaccharides were isolated from highly purified Saccharomyces cerevisiae invertase and shown by one-dimensional 1H NMR spectroscopy and alpha 1,2-linkage-specific mannosidase digestion to constitute a homologous series of nearly homogeneous compounds, which appeared to define the intermediates in oligosaccharide core synthesis in yeast (Trimble, R.B. and Atkinson, P.H. (1986) J. Biol. Chem., 261, 9815-9824). To evaluate whether invertase oligosaccharides reflected global core processing of yeast glycans, the soluble glycoprotein pool of disrupted log-phase cells was digested with endo-beta-N-acetyl-glucosaminidase H and Man8-13GlcNAc were isolated by Bio-Gel P-4 chromatography. Although analysis of each size class by one-dimensional 400 MHz and two-dimensional 500 MHz phase-sensitive COSY 1H NMR spectroscopy revealed considerable structural heterogeneity in all but Man8GlcNAc, the major positional isomer in Man9-13GlcNAc (approximately 50%) was identical to that previously elucidated on invertase. The heterogeneity resided in four families of oligosaccharides: (i) Glc3Man9GlcNAc----Man8 GlcNAc trimming intermediates; (ii) alpha-mannosidase degradation products of the principal isomers; (iii) mannan elongation intermediates; (iv) core structures with the alpha 1,2-linked mannose usually removed by the processing alpha-mannosidase. The potential for the vacuolar alpha-mannosidase (AMS1 gene product) to generate heterogeneity in vitro was confirmed by isolating oligosaccharides from AMS1 and ams1 yeast strains in the presence of a Man13GlcNAc[3H]-ol marker (where GlcNAc[3H]-ol is N-acetylglucosamin [1-3H]itol). Degradation of the Man13GlcNAc[3H]-ol to Man9-12GlcNAc[3H]-ol occurred in the former, but not in the latter. A role for the vacuolar alpha-mannosidase in generating at least some heterogeneity in vivo was inferred from the 1H NMR spectrum of the AMS1 Man11GlcNAc pool, which showed more structural isomerism than seen in the spectrum of a comparable ams1 Man11GlcNAc preparation. Thus, the principal biosynthetic pathway of inner core mannan in Saccharomyces is defined by the Man8-13GlcNAc oligosaccharides found on external invertase, while structural heterogeneity in these size classes results from precursor processing in the endoplasmic reticulum, core extension in the Golgi and metabolic degradation in the vacuole.

Acetylglucosamine↗
PubMed1992

Effects of timolol ophthalmic solution on the intra-ocular pressure rise induced by suxamethonium and tracheal intubation.

Thirty patients received topical application of either timolol ophthalmic solution 0.25%, or normal saline, 2 h before elective ophthalmic surgery in a double-blind study. The responses to suxamethonium and tracheal intubation were compared by measuring intra-ocular pressure before induction of anaesthesia, 1 min after administration of thiopentone 2-4 mg.kg-1, 1 min after administration of suxamethonium 1 mg.kg-1, and 1, 2.5 and 5 min after tracheal intubation. There was no significant difference between the groups.

Adult↗
PubMed1992

Rural medicine.

Explore the source record for details and available documents.

Iowa↗
PubMed1991

Structure of oligosaccharides on Saccharomyces SUC2 invertase secreted by the methylotrophic yeast Pichia pastoris.

Saccharomyces SUC2 invertase, secreted by the methylotrophic yeast Pichia pastoris and purified to homogeneity from the growth medium by DE-52 chromatography, appeared on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a diffuse ladder of species at 85-90 kDa, while the secreted Saccharomyces form migrated as a broad band from 100 to 150 kDa. Endo-beta-N-acetylglucosaminidase H released the Pichia invertase carbohydrate generating a 60-kDa protein with residual Asn-linked GlcNAcs and oligosaccharides separated on Bio-Gel P-4 into Man8-11GlcNAc. Nearly 75% of the oligosaccharides were equally distributed between Man8,9GlcNAc, while 17% were Man10GlcNAc and 8% were Man11GlcNAc. Oligosaccharide pools were analyzed for homogeneity by high-pH anion-exchange chromatography, and structures were assigned using 500 MHz one- and two-dimensional 1H NMR spectroscopy. Pichia Man8GlcNAc was the same isomer as found in Saccharomyces, which arises by removing the alpha 1,2-linked terminal mannose from the middle arm of the lipid-oligosaccharide Man9GlcNAc (Byrd, J. C., Tarentino, A. L., Maley, F., Atkinson, P. H., and Trimble, R. B. (1982) J. Biol. Chem. 257, 14657-14666). The Man9GlcNAc pool was 5% lipid-oligosaccharide precursor and 95% Man8GlcNAc isomer with a terminal alpha 1,6-linked mannose on the lower-arm alpha 1,3-core-linked residue (Hernández, L. M., Ballou, L., Alvarado, E., Gillece-Castro, B. L., Burlingame, A. L., and Ballou, C. E. (1989) J. Biol. Chem. 264, 11849-11856). An alpha 1,2-linked mannose on the new alpha 1,6-linked branch in Man9GlcNAc provided 80% of the Man10GlcNAc, which is the structure on Saccharomyces invertase (Trimble, R. B., and Atkinson, P. H. (1986) J. Biol. Chem. 261, 9815-9824). A minor Man10GlcNAc (12%) and the principal Man11GlcNAc (82%) were the major Man9,10GlcNAc with novel alpha 1,2-linked mannoses on the preexisting alpha 1,2-linked termini. Although Pichia glycans did not have terminal alpha 1,3-linked mannoses as found on Saccharomyces core oligosaccharides, over 60% of the structures were isometric configurations unique to lower eukaryotes.

Carbohydrate Sequence↗
PubMed1991

Structure of Saccharomyces cerevisiae alg3, sec18 mutant oligosaccharides.

Asparagine-linked oligosaccharides are synthesized by transfer of Glc3Man9GlcNAc2 from dolichol pyrophosphate to nascent polypeptides. Assembly of the precursor proceeds by highly ordered sequential addition of mannose and glucose to form Glc3Man9GlcNAc2-P-P-dolichol. Yeast mutants in asparagine-linked glycosylation (alg), generated by an 3H-Man suicide technique, were assigned to eight complementation groups which define steps in oligosaccharide-lipid synthesis (Huffaker, T.C., and Robbins, P.W. (1982) J. Biol. Chem. 257, 3203-3210). Alg3 invertase oligosaccharides are resistant to endo-beta-N-acetylglucosaminidase H, and the lipid-oligosaccharide pool yields Man5Glc-NAc2, suggesting its structure may be that from mammalian cells lacking Man-P-dolichol (Chapman, A., et al. (1980) J. Biol. Chem. 255, 4441-4446). To test this supposition, the endoplasmic reticulum form of invertase derepressed in alg3,sec18 yeast at 37 degrees C was isolated as a source of oligosaccharides whose processing beyond glucose and/or mannose trimming, if involved, would be prevented. Man8GlcNAc2 and Man5GlcNAc2 were released by peptide-N-glycosidase F from alg3,sec18 invertase in a 1:5 molar ratio. 1H NMR spectroscopy revealed Man8GlcNAc2 to be the alpha 1,2-mannosidase-trimming product described earlier (Byrd, J. C., Tarentino, A. L., Maley, F., Atkinson, P. H., and Trimble, R. B. (1982) J. Biol. Chem. 257, 14657-14666), while Man5GlcNAc2 was Man alpha 1, 2Man alpha 1,2Man alpha 1,3(Man alpha 1,6)Man beta 1,4GlcNAc beta 1, 4GlcNAc. This provides a structural proof for the lipid-linked Man5GlcNAc2 originally proposed from enzymatic and chemical analyses of the radiolabeled mammalian precursor. Experimental evidence indicates that, unlike the mammalian cell mutants which are unable to synthesize Man-P-dolichol, alg3 yeast accumulate Man5GlcNAc2-P-P-dolichol due to a defective alpha 1,3-mannosyltransferase required for the next step in oligosaccharide-lipid elongation.

Carbohydrate Conformation↗
PubMed1991

Identification of distinct endoglycosidase (endo) activities in Flavobacterium meningosepticum: endo F1, endo F2, and endo F3. Endo F1 and endo H hydrolyze only high mannose and hybrid glycans.

Flavobacterium meningosepticum endo-beta-acetyl-glucosaminidase F preparations have been resolved by hydrophobic interaction chromatography on TSK-butyl resin into at least three activities designated endo F1, endo F2 and endo F3 each with a unique substrate specificity. The 32-kDa endo F1 protein is the principle component representing in excess of 95% of most earlier and currently available commercial endoglycosidase preparations, the remainder being a mixture of five proteins from 32 to 43 kDa. Substrate specificity studies reveal endo F1 and endo H from Streptomyces plicatus to have nearly identical capacities to hydrolyze high-mannose oligosaccharides with a minimum Man1 alpha 3Man1 alpha 6Man1 beta 4GlcNAc1 beta 4GlcNAc structure. Although endo H will hydrolyze fucose-containing hybrid oligosaccharides at rates approaching comparable high-mannose forms, core-linked fucose reduces the hydrolysis rate of endo F1 by over 50-fold relative to high-mannose structures. Neither homogeneous endo F1 nor endo H hydrolyze complex multi-antennary glycans. The biantennary cleaving activity previously reported for endo F preparations (Tarentino, A. L., Gómez, C. M., and Plummer, T. H., Jr. (1985) Biochemistry 24, 4665-4671) is a characteristic of the contaminating endo F2 activity.

Acetylglucosaminidase↗
PubMed1991

Glycoprotein biosynthesis in yeast: purification and characterization of the endoplasmic reticulum Man9 processing alpha-mannosidase.

Saccharomyces cerevisiae Man9-alpha-mannosidase, responsible for trimming Man9GlcNAc2 in the endoplasmic reticulum to Man8GlcNAc2, the substrate for oligosaccharide elongation, has been purified to homogeneity from stabilized microsomal membranes without employing autolytic digestion. The activity was solubilized by the zwitterionic detergent, 3-[(3-cholamidopropyl)dimethyl ammonio]-1-propanesulphonate (CHAPS), whose presence was necessary for maximal activity. Purification included Q-Sepharose ion-exchange chromatography, preparative isoelectric focusing and HPLC gel filtration on TSK 3000 matrix. Overall purification from post-nuclear supernatants was estimated to be 110,000-fold with a 50% recovery of activity. The purified enzyme hydrolysed Man9GlcNAc1,2 from thyroglobulin or oligosaccharide-lipid, but not invertase Man9GlcNAc, Man1 alpha 2Man1 alpha OCH3 or p-nitrophenyl-alpha-D-mannopyranoside. Conversion of thyroglobulin Man9GlcNAc to Man8GlcNAc was linear with time and enzyme concentration, with an apparent Km of 0.2 mM and a specific activity of 220 IU/mg. Glc3Man9GlcNAc2 from oligosaccharide-lipid was as good a substrate as Man9GlcNAc, but the lipid-linked Man7GlcNAc2 isomer was hydrolysed at only 10% of this rate. Hydrolysis of defined isomers of IgM and bovine thyroglobulin Man6,7,8GlcNAc indicated that, for maximal alpha 1,2-mannosidase activity, only the alpha 1,2-linked terminal mannoses on the alpha 3 branch of the Man9GlcNAc precursor were dispensable. Isomers lacking the terminal alpha 1,2-linked mannose on the alpha 6 branch were hydrolysed at only approximately 10% of the maximal rate. The enzyme exhibited a pI of 5.3 and a pH optimum at 6.5. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis in the absence of reducing agents gave a single sharp band at 66 kDa, while in the presence of beta-mercaptoethanol equimolar amounts of two peptides, one of 44 kDa and one of 23 kDa, were obtained. Sizing on Sephacryl SF300, Superose 12 and TSK 3000 provided a holoenzyme mol. wt of 60-68 kDa, indicating that the isolated active form of the Man9-alpha-mannosidase was composed of one each of the sulphydryl-bonded dissimilar peptides. The enzyme bound to concanavalin A (ConA)-Sepharose and was eluted with alpha-methylmannoside, indicating the presence of high-mannose oligosaccharides. The Man9-alpha-mannosidase required low levels of Ca2+, which could be removed by EGTA. Activity was restored by Ca2+ or Zn2+, but not by Mg2+ or Mn2+.

Carbohydrate Sequence↗
PubMed1991

Health care reform.

Explore the source record for details and available documents.

Delivery of Health Care↗
PubMed1990

Metastatic pneumococcal endophthalmitis: report of two cases and review of literature.

Two patients with pneumococcal bacteraemia complicated by endophthalmitis are described. While this condition appears to have been relatively common in the preantibiotic era, a review of the literature since 1950 only identified six additional case reports. Analysis of these eight cases reveals two patterns: unilateral disease in six patients and bilateral disease with simultaneous onset in two patients. The potential pathogenic mechanisms--direct bacterial invasion or immunologically mediated processes--are discussed in relation to these clinical presentations. The critical importance of seeking ophthalmological advice early in the course of the disease is emphasised, as the risk of visual loss with systemic antimicrobials alone is very high, particularly if the infective process involves the vitreous humour.

Ampicillin↗
PubMed1988

Characterization of the glycosylation sites in yeast external invertase. II. Location of the endo-beta-N-acetylglucosaminidase H-resistant sequons.

There are 14 potential Asn-X-Thr/Ser glycosylation sites, or sequons, in the yeast external invertase sequence. Of these, 13 are wholly or partially glycosylated to give an average of 9-10 oligosaccharides/subunit (Reddy, V. A., Johnson, R. S., Biemann, K., Williams, R. S., Ziegler, F. D., Trimble, R. B., and Maley, F. (1988) J. Biol. Chem. 263, 6978-6985). On digestion of native holoenzyme by endo-beta-N-acetylglucosaminidase H (Endo H) an average of about seven oligosaccharides per subunit are released without affecting enzyme activity (Trimble, R. B., and Maley, F. (1977) J. Biol. Chem. 252, 4409-4412). To determine whether the remaining Endo H-resistant chains were restricted to a limited number of unique sequons or were randomly distributed on all 13, Endo H-treated native invertase was digested with either thermolysin or trypsin and the resultant glycopeptides isolated by reversed-phase high pressure liquid chromatography and gel filtration. It was found that the oligosaccharides attached to Asn92, Asn247, and Asn350 were partially resistant to Endo H, while those at Asn45 and Asn337) were completely resistant. Bio-Gel P-4 analysis revealed the Endo H-resistant oligosaccharides at Asn45, Asn92, Asn247, and Asn337 to be Man8-14GlcNAc, while the minor residual carbohydrate at Asn350 was Man greater than 50GlcNAc. The Endo H-susceptible oligosaccharides at Asn4, Asn146, and Asn256 were Man greater than 50GlcNAc while all other glycosylation sites contained Man8-14GlcNAc. Based on a hydropathic analysis of invertase, the two most Endo H-resistant oligosaccharides at Asn45 and Asn337 were located in the more hydrophobic regions of the molecule. These may form part of the folded protein structure or interacting subunit surfaces, thus restricting their accessibility to Endo H.

Acetylglucosaminidase↗