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Biomedical subjects

J S Reid

Publications and source records attributed to J S Reid.

At least 37 records · Page 2Linked to original sources
PubMed1994

Purification and properties of a novel beta-galactosidase or exo-(1-->4)-beta-D-galactanase from the cotyledons of germinated Lupinus angustifolius L. seeds.

The main polysaccharide component of the thickened cell walls in the storage parenchyma of Lupinus angustifolius L. cotyledons is a linear (1-->4)-beta-linked D-galactan, which is mobilised after germination (L. A. Crawshaw and J.S.G Reid, 1984, Planta 160, 449-454). The isolation from the germinated cotyledons of a beta-D-galactosidase or exo-(1-->4)-beta-D-galactanase with a high specificity for the lupin galactan is described. The enzyme, purified using diethylaminoethyl-cellulose, carboxymethyl-cellulose and affinity chromatography on lactose-agarose, gave two bands (major 60 kDa, minor 45 kDa) on sodium dodecyl sulphate-gel electrophoresis, and two similar bands on isoelectric focusing (major, pI 7.0, minor pI 6.7, both apparently possessing enzyme activity). The minor component cross-reacted with an antiserum raised against, and affinity-purified on, the major band. Both components had a common N-terminal sequence. The minor component was probably a degradation product of the major one. The enzyme had limited beta-galactosidase action, catalysing the hydrolysis of p-nitrophenyl-beta-D-galactopyranoside and (1-->4)- and (1-->6)-beta-linked galactobioses. Lactose [beta-D-galactopyranosyl-(1-->4)-D-glucose] was hydrolysed only very slowly and methyl-beta-D-galactopyranoside not at all. Lupin galactan was hydrolysed rapidly and extensively to galactose, whereas other cell-wall polysaccharides (xyloglucan and arabinogalactan) with terminal non-reducing beta-D-galactopyranosyl residues were not substrates. A linear (1-->4)-beta-linked galactopentaose was hydrolysed efficiently to the tetraose plus galactose, but further sequential removals of galactose to give the tetraose and lower homologues occurred more slowly. Galactose, gamma-galactonolactone and Cu+2 were inhibitory. No endo-beta-D-galactanase activity was detected in lupin cotyledonary extracts, whereas exo-galactanase activity varied pari passu with galactan mobilisation. Exo-galactanase protein was detected, by Western immunoblotting of cotyledon extracts, just before the activity could be assayed and then increased and decreased in step with the enzyme activity. The exo-galactanase is clearly a key enzyme in galactan mobilisation and may be the sole activity involved in depolymerising the dominant (1-->4)-beta-galactan component of the cell wall.

Carbohydrate Sequence↗
PubMed1994

Simple intraoperative traction system for acetabular fracture surgery.

The open reduction and internal fixation of complex acetabular fractures generally require some amount of sustained intraoperative traction. This traction can be provided by either specialized traction tables or scrubbed assistants. Both methods have their advantages and disadvantages. Specialized traction tables provide excellent controlled traction but are costly. Interested assistants are less costly, but at many institutions an adequate number of them are unavailable. We describe the design, construction, and use of a simple intraoperative traction device to aid in the open reduction and internal fixation of acetabular fractures.

Acetabulum↗
PubMed1994

Assessment of glass polyalkenoate restorations in primary molar teeth.

This study assess the suitability of glass polyalkenoate cement as a restorative material in primary molars, when placed by community dental officers in their own clinics. Nine officers placed the restorations and two assessors examined the restorations after one and three years, recording details of the success or failure of each restoration. A total of 635 glass polyalkenoate restorations were placed and, after one year, 149 (23.4%) of these had failed. Of the 359 available for examination after three years, a further 142 (22.4%) had failed, leaving 217 (42.7%) intact. This study shows that the major factor in the successful use of glass polyalkenoate cements as a restorative material in deciduous molars is the classification type of cavity. A significant number of Class II restorations failed within the first year. The study confirms that glass polyalkenoate cements provide a satisfactory means of restoring Class I cavities in primary teeth.

Chi-Square Distribution↗
PubMed1993

Action of a pure xyloglucan endo-transglycosylase (formerly called xyloglucan-specific endo-(1-->4)-beta-D-glucanase) from the cotyledons of germinated nasturtium seeds.

The action on tamarind seed xyloglucan of the pure, xyloglucan-specific endo-(1-->4)-beta-D-glucanase from nasturtium (Tropaeolum majus L.) cotyledons has been compared with that of a pure endo-(1-->)-beta-D-glucanase ('cellulase') of fungal origin. The fungal enzyme hydrolysed the polysaccharide almost completely to a mixture of the four xyloglucan oligosaccharides: [formula: see text] Exhaustive digestion with the nasturtium enzyme gave the same four oligosaccharides plus large amounts of higher oligosaccharides and higher-polymeric material. Five of the product oligosaccharides (D, E, F, G, H) were purified and shown to be dimers of oligosaccharides A to C. D (glc8xyl6) had the structure A-->A, H (glc8xyl6 gal4) was C-->C, whereas E (glc8xyl6gal), F (glc8xyl6gal2) and G (glc8xyl6gal3) were mixtures of structural isomers with the appropriate composition. For example, F contained B2-->B2 (30%), A-->C (30%), C-->A (20%), B2-->B1 (15%) and others (about 5%). At moderate concentration (about 3 mM) oligosaccharides D to H were not further hydrolysed by the nasturtium enzyme, but underwent transglycosylation to give oligosaccharides from the group A, B, C, plus higher oligomeric structures. At lower substrate concentrations, hydrolysis was observed. Similarly, tamarind seed xyloglucan was hydrolysed to a greater extent at lower concentrations. It is concluded that the xyloglucan-specific nasturtium-seed endo-(1-->4)-beta-D-glucanase has a powerful xyloglucan-xyloglucan endo-transglycosylase activity in addition to its known xyloglucan-specific hydrolytic action. It would be more appropriately classified as a xyloglucan endo-transglycosylase. The action and specificity of the nasturtium enzyme are discussed in the context of xyloglucan metabolism in the cell walls of seeds and in other plant tissues.

Carbohydrate Sequence↗
PubMed1993

Molecular characterization of a xyloglucan-specific endo-(1-->4)-beta-D-glucanase (xyloglucan endo-transglycosylase) from nasturtium seeds.

A novel xyloglucan-specific endo-(1-->4)-beta-D-glucanase, involved in the post-germinative mobilization of xyloglucan storage reserves, has previously been isolated from nasturtium (Tropaeolum majus L.) seed. Its mode of action has been shown, in vitro, to be one of transglycosylation except at low substrate (glycosylacceptor) concentrations when hydrolysis predominates. Here it is shown that this nasturtium seed xyloglucan endo-transglycosylase is encoded by a single gene which is transcribed and processed to a 1.5 kb mRNA. The isolation and DNA sequence analysis of a cDNA copy of the nasturtium xyloglucan endo-transglycosylase transcript is described. The cDNA encodes a 33.5 kDa precursor polypeptide which is subsequently processed to a 31 kDa mature protein. The precursor incorporates an N-terminal signal sequence which probably contains information relevant to the targeting of the enzyme to the cell wall. The computer-predicted isoelectric point (5.14) and low (approximately 0%) alpha-helix content of the deduced mature protein are in excellent agreement with the experimental data obtained using the purified enzyme. The deduced protein sequence lacks homology with known plant endo-(1-->4)-beta-D-glucanases, consistent with the unique properties of the enzyme. Database searches have revealed that a Brassica protein (meri-5) of previously unknown function, but abundantly expressed in expanding tissue, shares structural identity with the nasturtium xyloglucan endo-transglycosylase. The expression of a xyloglucan endo-transglycosylase in expanding tissue would be consistent with the contention that enzymes of this type are involved in cell wall loosening.

Amino Acid Sequence↗
PubMed1993

Marginal fit and microleakage of indirect inlay systems.

Three different indirect adhesive inlay systems were investigated for marginal fit and microleakage. MOD cavities were prepared in 67 extracted sound premolar teeth initially with parallel cavity walls. Thirty-four of the premolars had the cavity walls modified to a 10 degrees and 33 to a 15 degrees occlusal divergence. EOS, Isosit and Hi-Ceram porcelain inlays did not fit cavities prepared with parallel walls. All inlays in the Isosit and porcelain groups were able to be seated without modifications in cavities prepared with either a 10 degrees or 15 degrees occlusal divergence. Inlays made by the EOS system required considerable modification of the fitting surface in order for them to fit. Results showed the EOS system to have the largest marginal gaps before cementation (P < 0.001). There was no significant difference in leakage between the three inlay systems after cementation (P < 0.05). The cementum margins leaked more than margins finished on enamel for all inlay systems (P < 0.05). It is concluded from this study that inlay cavities for Isosit and porcelain require at least a 10 degrees occlusal divergence of cavity walls to permit the fitting of inlays without unacceptable modification. The EOS inlays required considerable trimming even when a 15 degrees occlusal divergence of the cavity walls was used.

Acrylic Resins↗
PubMed1992

Pitted enamel hypoplasia in tuberous sclerosis.

Thirty patients with tuberous sclerosis (from 29 different families) were examined for evidence of macroscopically visible pitted enamel hypoplasia. Of 23 patients with permanent teeth, 11 (48%) showed multiple enamel pits (mean 4.6 pits, range 3-9), but none were seen in six patients with deciduous teeth. Five of 563 controls (0.88%) had similar pitted enamel hypoplasia. Simple dental examination may be a useful adjunct in the assessment of patients with permanent teeth when a diagnosis of tuberous sclerosis is being considered, but is less likely to be helpful in the pre-school child.

Adolescent↗
PubMed1992

The Ellison iliotibial-band transfer for a torn anterior cruciate ligament of the knee. Long-term follow-up.

We studied the long-term results of the Ellison technique of extra-articular transfer of the iliotibial band, without advancement of the biceps tendon, as the sole operative treatment for a torn anterior cruciate ligament. Thirty-two patients (thirty-two knees) were evaluated an average of eleven years (range, seven to fifteen years) after the operation. The average age at the time of the operation was twenty-two years (range, sixteen to thirty-four years). Eighteen patients (56 per cent) had a modified Lysholm score of less than 84 points, indicating symptoms during the activities of daily living. Only six patients (19 per cent) had a subjectively normal knee (a modified Lysholm score of more than 94 points). The most common reason for a poor subjective score was the presence of symptoms of instability, in twenty-four patients (75 per cent). Twenty-four patients (75 per cent) had a positive pivot-shift test and twenty-nine patients (91 per cent), a positive Lachman test. Twelve patients (38 per cent) had severe (grade 3 or 4) radiographic changes. The radiographs of the knee appeared normal (grade 0) in only eight patients (25 per cent). There was a significant association between a meniscal injury and radiographic changes (p < 0.05). Fourteen patients (44 per cent) had subsequent procedures due to persistent instability or pathological changes in the articular cartilage or in a meniscus. There was a significant decline in the subjective and objective knee scores in the twenty-one patients who were evaluated at both two and eleven years. The number of patients who had a positive pivot-shift test increased from five (24 per cent) to sixteen (76 per cent). Subjectively, the number of patients who had a good result decreased from fourteen (67 per cent) to five (24 per cent). Objectively, nine patients (43 per cent) had a rating of good at two years; this fell to three (14 per cent) at eleven years. Symptomatic instability, pain, and a positive pivot-shift test were the most common reasons for a poor result. Because of the decline in the subjective and objective scores, we no longer recommend the Ellison procedure as the sole operative treatment for a torn anterior cruciate ligament of the knee.

Adolescent↗
PubMed1991

Structure and solution properties of tamarind-seed polysaccharide.

The major polysaccharide in tamarind seed is a galactoxyloglucan for which the ratios galactose:xylose:glucose are 1:2:25:2.8. A minor polysaccharide (2-3%) contains branched (1----5)-alpha-L-arabinofuranan and unbranched (1----4)-beta-D-galactopyranan features. Small-angle X-ray scattering experiments gave values for the cross-sectional radius of the polymer in aqueous solution that were typical of single-stranded molecules. Marked stiffness of the chain (C infinity 110) was deduced from static light-scattering studies and is ascribed partially to the restriction of the motion of the (1----4)-beta-D-glucan backbone by its extensive (approximately 80%) glycosylation. The rigidity of the polymer caused significant draining effects which heavily influenced the hydrodynamic behaviour. The dependence of "zero-shear" viscosity on concentration was used to characterise "dilute" and "semi-dilute" concentration regimes. The marked dependence on concentration in the "semi-dilute" region was similar to that for other stiff neutral polysaccharide systems, ascribed to "hyper-entanglements", and it is suggested that these may have arisen through a tenuous alignment of stiffened chains.

Carbohydrate Conformation↗
PubMed1991

Enzyme-gold cytochemistry of seed xyloglucans using two xyloglucan-specific hydrolases. Importance of prior heat-deactivation of the enzymes.

Two pure, homogeneous xyloglucan-hydrolyzing enzymes from germinated nasturtium seeds have been used to localize xyloglucans specifically in seed cell walls. The enzymes, a novel endo (1----4)-beta-D-glucanase which shows absolute specificity towards xyloglucans and a beta-D-galactosidase which is capable of removing galactosyl residues from polymeric xyloglucans, were used to stabilize gold sols. The complexes were applied to ultrathin sections of nasturtium (Tropaeolum majus L) and tamarind (Tamarindus indica L) seeds. The gold complexes prepared from the active enzyme proteins retained enzyme activity, and such complexes gave extremely weak section-labelling or no labelling at all. When the enzymes were subjected to heat-deactivation before being used to stabilize the gold sols, gold complexes were obtained which lacked enzyme activity, but which gave strong, specific labelling of xyloglucans in ultrathin sections. The specificity of the labelling was checked by substrate-competition, by pretreatment of sections with the active and heat-denaturated enzymes and by comparing the labelling of xyloglucan-containing storage cells with other cell types in the same section. The labelling was maximal at the pH which was optimal for the active enzyme. We conclude that the enzyme-gold complexes which retain high activity against the substrate to be localized are likely to be unsuitable as cytochemical probes because they may cause in situ substrate modification. In the case of the enzyme complexes described here the specific localization obtained with the gold complexes prepared from heat deactivated enzymes may be attributable to the retention by the heat-treated enzymatically-inactive proteins of substrate recognition.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1991

Gingival health associated with porcelain veneers on maxillary incisors.

The possible detrimental effect of acid-etched resin-bonded prostheses and porcelain veneers on plaque accumulation and gingival health is currently disputed. Some workers recommend no tooth preparation prior to veneering whilst others recommend tooth preparation to prevent adverse gingival soft tissue reactions. In order to test the possible gingival effects of veneers placed without tooth preparation, this study was set up to compare gingival health on veneered and non-veneered maxillary incisors within the same individual during periods of normal tooth cleaning and of no tooth cleaning. No significant differences were noted in plaque or gingival indices, or in gingival crevicular fluid volume, between the 72 veneered and non-veneered sites during either study period. The results of this study suggest that placing porcelain veneers on unprepared teeth does not increase the risk of gingivitis.

Adult↗
PubMed1991

Measurement of de novo hepatic lipogenesis in humans using stable isotopes.

Direct measurement of de novo lipogenesis has not previously been possible in humans. We measured de novo hepatic lipogenesis in normal men by means of stable isotopes and by combining the acetylated-xenobiotic probe technique with mass isotopomer analysis of secreted very low density lipoprotein-fatty acids (VLDL-FA). Sulfamethoxazole (SMX) was administered with [13C]acetate during an overnight fast followed by refeeding with intravenous glucose (7-10 mg/kg of weight per min), oral Ensure (7-10 mg of carbohydrate/kg of weight per min), or a high-carbohydrate mixed-meal breakfast (3.5 g of carbohydrate/kg of weight). Respiratory quotients remained less than 1.0. High-performance liquid chromatography/mass spectrometry-determined enrichments in SMX-acetate attained stable plateau values, and hepatic acetyl-coenzyme A (CoA) dilution rate did not increase with refeeding (approximately 0.024 mmol/kg per min). The fraction of VLDL-palmitate derived from de novo lipogenesis was only 0.91 +/- 0.27% (fasted) and 1.64-1.97% (fed). For stearate, this was 0.37 +/- 0.08% and 0.47-0.64%. Precursor enrichments predicted from isotopomer ratios were close to measured SMX-acetate enrichments, indicating that SMX-acetate samples the true lipogenic acetyl-CoA pool. Stearate synthesis was less than palmitate and the two did not move in parallel. Estimated total VLDL-FA synthesis is less than 500 mg/day. Thus, de novo hepatic lipogenesis is a quantitatively minor pathway, consistent with gas exchange estimates; fatty acid futile cycling (oxidation/resynthesis) is not thermogenically significant; and synthesis rates of different nonessential fatty acids by human liver are not identical in nonoverfed normal men. The contribution and regulation of de novo lipogenesis in other settings can be studied using this technique.

Acetyl Coenzyme A↗
PubMed1991

A review of referral patterns to paediatric dental consultant clinics.

A retrospective survey of 317 child patients referred to consultant paediatric dental clinics at Glasgow Dental Hospital over a 12-month period is reported. It was found that although there was a wide range of reasons for referral the most frequent problem was the management of the patient. As a result of this finding, the dental hospital is currently establishing a clinic specifically for patients with a fear of dental treatment.

Adolescent↗