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Biomedical subjects

T Beveridge

Publications and source records attributed to T Beveridge.

At least 19 recordsLinked to original sources
PubMed2002

Processing effects on the composition of sea buckthorn juice from Hippophae rhamnoides L. Cv. Indian Summer.

Sea buckthorn juice is one product that can be derived from the sea buckthorn berry, a new alternative crop for the Canadian western provinces. Fresh pressed juice separates into three phases when allowed to stand overnight in the refrigerator: an upper cream phase, juice in the middle portion, and a sediment at the bottom. Enzymatic hydrolysis with commercial, broad spectrum carbohydrate hydrolyzing enzyme preparations reduced the juice viscosity, assisted juice separation, and provided an opalescent juice. Soluble solids averaged 10.2 degrees Brix, pH averaged 3.13, ascorbic acid averaged 174.2 mg/100 mL, and titratable acidity averaged 1.97% as malic acid all determined on centrifuged (10 000 rpm, 15 min) juice. Soluble sugars included glucose, fructose, and an unidentified component that was not sucrose or other common soluble monomeric or dimeric sugar. Quinic acid was quantitatively most important, while malic was next, and oxalic, citric, and tartaric acids were minor components. Washing berries by dipping reduced soluble solids (degrees Brix) in juice suggesting uptake of wash water.

Beverages↗
PubMed2001

Deletion of the cell-division inhibitor MinC results in lysis of Neisseria gonorrhoeae.

The minCDE genes involved in division site selection in Neisseria gonorrhoeae were identified using raw data from the N. gonorrhoeae genome project and are part of a cluster of 27 genes. When gonococcal min genes were heterologously expressed as a cluster in Escherichia coli, minicells and filaments were produced, indicating that gonococcal min genes disrupted cell division in other genera. The insertional inactivation of the minC gene of N. gonorrhoeae CH811 resulted in a strain (CSRC1) with decreased viability and grossly abnormal cell division as observed by phase-contrast and electron microscopy analysis. Western blot analysis of N. gonorrhoeae CSRC1 confirmed that MinC(Ng) was not produced. Complementation of CSRC1 by integrating a minC-6xHis tag fusion at the proAB locus by homologous recombination restored viability and 1.9 times wild-type levels of MinC(Ng) expression. This slight increase of expression caused a small percentage of the complemented cells to divide aberrantly. This suggested that the 6xHis tag has partially affected the stability of MinC, or that the chromosomal position of minC is critical to its regulation. Comparison of MinC proteins from different bacteria showed a homologous region corresponding to residues 135-230 with five conserved amino acids. Overexpression of MinC(Ng) in wild-type E. coli cells induced filamentation and an E. coli minC mutant was successfully complemented with minC(Ng). Therefore, the evidence indicates that MinC from N. gonorrhoeae acts as a cell-division inhibitor and that its role is essential in maintaining proper division in cocci.

Bacterial Proteins↗
PubMed2000

On the architecture of the gram-negative bacterial murein sacculus.

The peptidoglycan network of the murein sacculus must be porous so that nutrients, waste products, and secreted proteins can pass through. Using Escherichia coli and Pseudomonas aeruginosa as a baseline for gram-negative sacculi, the hole size distribution in the peptidoglycan network has been modeled by computer simulation to deduce the network's properties. By requiring that the distribution of glycan chain lengths predicted by the model be in accord with the distribution observed, we conclude that the holes are slits running essentially perpendicular to the local axis of the glycan chains (i. e., the slits run along the long axis of the cell). This result is in accord with previous permeability measurements of Beveridge and Jack and Demchik and Koch. We outline possible advantages that might accrue to the bacterium via this architecture and suggest ways in which such defect structures might be detected. Certainly, large molecules do penetrate the peptidoglycan layer of gram-negative bacteria, and the small slits that we suggest might be made larger by the bacterium.

Carbohydrate Conformation↗
PubMed1999

Sea buckthorn products: manufacture and composition.

Sea buckthorn (Hippophae rhamnoides) is a unique plant currently being domesticated. The fruit is the main component of value, although the leaves are occasionally made into sea buckthorn tea. The two main sources of valuable products are derived from the berries, juice from the fleshy tissue and seed as a single seed from each berry. The juice provides a nutritious beverage, high in suspended solids and very high in vitamin C and carotenes. The juice may contain an oil phase trapped within the suspended solids, or the oil may be removed as pulp oil and provided separately. The pulp remaining after juice removal provides for extraction of "sea buckthorn yellow", a pigment that has potential use as a food coloring material. The seed is a source of seed oil, which is very unsaturated and shows promise, because of its light absorption and emollient properties, as an ingredient in cosmetics, phytopharmaceuticals, or UV skin protectant preparations. It may be prepared by conventional extraction techniques or by supercritical carbon dioxide extraction. The manufacture of the main products derived from sea buckthorn is described, including several examples from the patent literature. The available compositional data for the main products are tabulated to form a comprehensive source of information on the manufacture and composition of sea buckthorn products.

Ascorbic Acid↗
PubMed1999

Thickness and elasticity of gram-negative murein sacculi measured by atomic force microscopy.

Atomic force microscopy was used to measure the thickness of air-dried, collapsed murein sacculi from Escherichia coli K-12 and Pseudomonas aeruginosa PAO1. Air-dried sacculi from E. coli had a thickness of 3.0 nm, whereas those from P. aeruginosa were 1.5 nm thick. When rehydrated, the sacculi of both bacteria swelled to double their anhydrous thickness. Computer simulation of a section of a model single-layer peptidoglycan network in an aqueous solution with a Debye shielding length of 0.3 nm gave a mass distribution full width at half height of 2.4 nm, in essential agreement with these results. When E. coli sacculi were suspended over a narrow groove that had been etched into a silicon surface and the tip of the atomic force microscope used to depress and stretch the peptidoglycan, an elastic modulus of 2.5 x 10(7) N/m(2) was determined for hydrated sacculi; they were perfectly elastic, springing back to their original position when the tip was removed. Dried sacculi were more rigid with a modulus of 3 x 10(8) to 4 x 10(8) N/m(2) and at times could be broken by the atomic force microscope tip. Sacculi aligned over the groove with their long axis at right angles to the channel axis were more deformable than those with their long axis parallel to the groove axis, as would be expected if the peptidoglycan strands in the sacculus were oriented at right angles to the long cell axis of this gram-negative rod. Polar caps were not found to be more rigid structures but collapsed to the same thickness as the cylindrical portions of the sacculi. The elasticity of intact E. coli sacculi is such that, if the peptidoglycan strands are aligned in unison, the interstrand spacing should increase by 12% with every 1 atm increase in (turgor) pressure. Assuming an unstressed hydrated interstrand spacing of 1.3 nm (R. E. Burge, A. G. Fowler, and D. A. Reaveley, J. Mol. Biol. 117:927-953, 1977) and an internal turgor pressure of 3 to 5 atm (or 304 to 507 kPa) (A. L. Koch, Adv. Microbial Physiol. 24:301-366, 1983), the natural interstrand spacing in cells would be 1.6 to 2.0 nm. Clearly, if large macromolecules of a diameter greater than these spacings are secreted through this layer, the local ordering of the peptidoglycan must somehow be disrupted.

Cell Wall↗
PubMed1998

Particle development in apple juice determined by light scattering and electron microscopy.

Light scattering was used to detect the kinetic development of particles in apple juices produced with and without oxidation and in procyanidin extracts prepared from these two juices. Particle size developed exponentially in both oxidized and unoxidized juices, suggesting an enzymatic origin for the particle forming reactions. The procyanidin extract from oxidized juices produced particles which grew linearly, suggesting diffusion-controlled aggregation or coalescence of particles. Procyanidins from unoxidized juice showed no particle development over at least 60 days of storage. Electron microscopy showed particles similar to those seen previously and some newly described morphologies. The mechanism of haze particle development is discussed in the light of the light scattering and electron microscopic results.

Beverages↗
PubMed1997

Atomic force microscope measurements of long-range forces near lipid-coated surfaces in electrolytes.

The interaction of DMPC (L-alpha-dimyristoyl-1,2-diterradecanoyl-sn-glycero-3-phosphoch oli ne, C36H72NO8P) lipid-coated Si3N4 surfaces immersed in an electrolyte was investigated with an atomic force microscope. A long-range interaction was observed, even when the Si3N4 surfaces were covered with nominally neutral lipid layers. The interaction was attributed to Coulomb interactions of charges located at the lipid surface. The experimental force curves were compared with solutions for the linearized as well as with exact solutions of the Poisson-Boltzmann equation. The comparison suggested that in 0.5 mM KCl electrolyte the DMPC lipids carried about one unit of charge per 100 lipid molecules. The presence of this surface charge made it impossible to observe an effective charge density recently predicted for dipole layers near a dielectric when immersed in an electrolyte. A discrepancy between the theoretical results and the data at short separations was interpreted in terms of a decrease in the surface charge with separation distance.

Dimyristoylphosphatidylcholine↗
PubMed1997

Haze and cloud in apple juices.

Turbidity in apple juice is desirable or undesirable, depending on whether the product fits within consumer expectations. Desirable opalescence is due to soluble pectin and insoluble pectin stabilized particles that show considerable stability. Blanching treatments enhance this stability by reducing particle size and character-solubilizing pectin, and possibly by the destruction of natural enzymes that may destabilize the cloud over time. Undesirable haze and sediments may arise in apple juice by several mechanisms, including starch (dextrin) retrogradation, protein phenol aggregation, phenol oxidation, crystallization of carbohydrate macromolecules extracted from cell walls, or difficulties during manufacture. The mechanisms of formation of each of these forms of haze are discussed and examples given form the literature. Where available, haze-sediment morphology by light and/or electron microscopy is documented and the possible role of recently developed "macerase" enzymes in haze/sediment formation discussed.

Beverages↗
PubMed1997

Juice extraction from apples and other fruits and vegetables.

Presses are the usual and traditional method of removing juice from fruit and vegetable materials. However, recently diffusion extraction, centrifugation, and specialized ultrafiltration techniques have been explored and have been exploited commercially to a limited extent. Yield efficiency diagrams that relate juice yields to mash feed rates provide a mechanism for comparing presses and other processes such as enzyme treatments or decanter centrifuges for efficiency under a stated set of circumstances. Diffusion extraction is capable of removing 90 to 94% of soluble solids from properly prepared apple slices, but the resulting juice is diluted with extraction water and is high in extracted tannins. Concentration is necessary to obtain juice solids equivalency, and the resulting juice has sour/astringent flavors that must be removed with tannin absorbants to provide acceptable flavor. Currently, decanter centrifuges are used commercially and have provided an alternative to presses under certain circumstances. When naturally colored and flavored (unoxidized) juices are desired, the decanter provides a useful alternative to presses because it is easily inert gas blanketed. Utilization of a metallic ultrafilter as a press has been patented but has not achieved commercial utilization. The technical literature describing the application of these juice extraction juices, primarily to apples, is reviewed extensively.

Beverages↗
PubMed1992

IX 207-887 in rheumatoid arthritis. A double-blind placebo-controlled study.

OBJECTIVE: To determine the efficacy and the safety of IX 207-887 treatment in rheumatoid arthritis. The IX compound [10-methoxy-4H-benzo(4,5)cyclohepta-(1,2-b)thiophene-4-yliden acetic acid] is effective in several animal models of rheumatoid arthritis and has a mechanism of action involving the inhibition of interleukin-1 release. METHODS: A double-blind, controlled trial of 16 weeks' duration comparing placebo with IX at a daily dosage of 800 mg or 1,200 mg (20 patients/group) was conducted. RESULTS: Thirteen patients withdrew from the study, 3 because of lack of efficacy (all in the placebo group) and 10 because of side effects (1 in the placebo group [skin rash] and 9 in the IX groups [skin rash in 5, intestinal disturbances in 2, hepatitis in 1, meningitis in 1]). Intent-to-treat analysis showed a statistically significant difference in the variations of clinical and laboratory parameters between the 3 groups. Between-group comparisons showed an improvement in all these variables in the IX groups versus the placebo group. According to Paulus' criteria, 2 of the 20 placebo-treated patients (10%), 9 of the 20 IX 800 mg-treated patients (45%), and 11 of the 20 IX 1,200 mg-treated patients (55%) were considered responders (P = 0.008). CONCLUSION: The findings of this study suggest that the tolerability of IX is acceptable in rheumatoid arthritis patients, and that IX is an effective slow-acting drug for use in rheumatoid arthritis.

Adult↗
PubMed1992

The efficacy and tolerability of cyclosporine G in human kidney transplant recipients.

Twelve consecutive first cadaveric kidney transplant recipients received cyclosporine G (CsG)(initial dose 12 mg/kg per day) as basic immunosuppressive treatment along with prednisone (initial dose 0.5 mg/kg per day) for the first three months after transplantation. Thereafter CsG was replaced by Sandimmun (cyclosporine, CsA). Evaluation of the immunosuppressive efficacy and assessment of possible side effects of CsG was made and compared with the results in 38 historical control patients starting with the same dose of CsA as part of the same immunosuppressive dosage schedule. Statistically, there was no difference in patient survival at three (91% in CsG group versus 95% in CsA group) and twelve months (91% in CsG group versus 92% in CsA group), or in graft survival at three (75% in CsG group versus 89% in CsA group) and twelve months (75% in CsG group versus 84% in the CsA group). At equivalent oral doses of CsG and CsA significantly higher blood levels of CsG were observed (2P less than 0.05). Nephrotoxicity assessed by graft biopsy could be demonstrated to a similar extent in both groups, whereas hepatotoxicity was more pronounced during CsG treatment. Sequential measurements of bilirubin revealed a significant increase in all patients but median values were significantly higher in the CsG patients. A pronounced and concordant elevation of liver enzymes occurred during CsG treatment in three out of 12 patients. Liver biopsies performed in these patients revealed histological alterations consistent with toxic liver injury. Thus, in human kidney transplant recipients CsG and CsA appeared to be equally immunosuppressive and nephrotoxic but more hepatotoxic. On the basis of this limited experience we conclude that in human kidney transplant recipients CsG has no advantage over CsA.

Adult↗
PubMed1988

Pharmacokinetics of cyclosporine G in patients with renal failure.

The pharmacokinetics of the cyclosporine A (CsA, Sandimmune) analogue Nva2-cyclosporine, or cyclosporine G (CsG) was investigated in 6 patients with terminal renal failure after a 4-hr intravenous infusion (3.5 mg/kg) and after oral administration (600 mg) of the drug. Blood samples were collected up to 38 hr and CsG concentrations were measured by radioimmunoassay and high-performance liquid chromatography. The resulting pharmacokinetic parameters of CsG were similar to those described for CsA in the same patient population. Based on HPLC determinations, a mean terminal elimination half-life of 18.9 hr was calculated. The total body clearance was 0.55 L/hr/kg, the volume of the central compartment was 0.32 L/kg, and the steady-state volume of distribution was 5.97 L/kg. After oral administration maximum CsG concentrations in blood were reached between 2.5 and 3 hr, and the bioavailability was in the range of 24-55% (mean 36%). The ratios between the polyvalent RIA and HPLC determinations were considerably larger after oral dosing than after i.v. infusion. The blood-to-plasma ratio was 1.23, which is smaller than that observed for CsA. These results suggest that in patients undergoing renal transplantation the same dosing strategies can be applied for CsG as have been established for CsA.

Adult↗
PubMed1987

Cellular incorporation of poly-beta-hydroxybutyrate into plasma membranes of Escherichia coli and Azotobacter vinelandii alters native membrane structure.

Under growth-limiting conditions or conditions which mediate genetic transformation, Escherichia coli and Azotobacter vinelandii incorporate poly-beta-hydroxybutyrate into their plasma membranes. Genetic transformation competence of both bacteria increased in proportion to the concentration of membrane poly-beta-hydroxybutyrate. The effects of this lipid polymer on membrane structure were investigated by freeze-fracture electron microscopy. Before poly-beta-hydroxybutyrate incorporation, freeze-fracture revealed a typical mosaic of particles and pits on both concave and convex surfaces of the plasma membrane. As the cells incorporated the lipid polymer into the membrane, transformability developed and small semiregular plaques which possessed shallow particles were seen. These plaques grew in size and frequency as the membrane poly-beta-hydroxybutyrate concentrations and transformability increased.

Azotobacter↗