PubMed Health⌕ Search

Biomedical subjects

M J Groves

Publications and source records attributed to M J Groves.

At least 19 recordsLinked to original sources
PubMed1995

An anti-neoplastic glycan isolated from Mycobacterium bovis (BCG vaccine).

Tice substrain BCG is used clinically as an immunotherapeutic agent against superficial bladder cancer. A boiling-water extract of this BCG showed anti-tumour activity against a murine S180 sarcoma model and was fractionated into three fractions, A, B and C, by the use of Sephadex LH-20 chromatography. An anti-tumour glucan, PS1A1, was isolated from fraction PS1A with Sephadex G-75. The molecular mass of PS1A1 was between 65 and 87 kDa by Sephadex G-100 chromatography. The structure of PS1A1 was investigated by one- and two-dimensional NMR spectroscopy and methylation analysis and was demonstrated to be primarily 1-->6-alpha-linked glucose units. We postulate that the repeating unit is: [Formula: see text]

Animals↗
PubMed1995

The use of gelatin microparticles to delay the release of readily water-soluble materials.

The adsorption of D-arabinose onto gelatin microparticles demonstrated a Langmuirian adsorption pattern. Evaluation of the dissolution behaviour of D-arabinose-loaded gelatin microparticles suggested that the saccharide, loaded at a level below the adsorption saturation level, was released uniformly over a 14-h period after the loaded gelatin microparticles had been lyophilized for a second time. When dissolution curves were corrected for the initial burst effect seen after the gelatin microparticles had been loaded at higher levels of D-arabinose and lyophilized, steady-state release rates were also evident over prolonged periods. In addition, it was evident that the D-arabinose was adsorbed onto internal surfaces of the hydrated gelatin matrix. Calculation of this internal surface demonstrated the influence of the concentration of the glutaraldehyde used as a cross-linking agent and this parameter, in turn, influenced both the adsorption maxima and the subsequent equilibrium release rates. Application of this data base to a highly water-soluble complex polysaccharide antineoplastic agent, which has a higher molecular weight (22.4 kDa vs 150 Da), demonstrated similar behaviour in that a near zero-order release pattern over at least 16 h could be obtained by attention to the conditions under which the gelatin microparticles were made and subsequently loaded before lyophilization.

Adsorption↗
PubMed1995

Interaction between fibronectin-bearing surfaces and Bacillus Calmette-Guérin (BCG) or gelatin microparticles.

Gelatin, prepared commercially by degradation of animal collagen, was studied to see whether it had an affinity for fibronectin, which has a known affinity for collagen, and whether gelatin-based drugs could be used to target fibronectin-excreting tumours. Bacillus Calmette-Guérin (BCG) vaccine, an attenuated strain of Mycobacterium bovis, is currently the most effective treatment for superficial transitional cell carcinoma of the bladder. The living cells of the BCG vaccine associate with the fibronectin-bearing surfaces of the tumour. Using a multi-well culture plate technique, gelatin microparticles were shown to be adsorbed onto murine S180 sarcoma cells and this reaction was substantially inhibited by the addition of human plasma fibronectin. The avidities of various BCG substrains and gelatin microparticles for glass-bound fibronectin were measured and the association constants determined. The gelatin microparticles associated with the fibronectin with equal avidity as the BCG cells. The results suggest that this model system may allow the investigation of gelatin-based drug delivery devices capable of targeting fibronectin-bearing surfaces associated with some tumours.

Adsorption↗
PubMed1994

Use of the Walden Product to evaluate the effect of amino acids on water structure.

The Walden Product, the product of viscosity (eta 0) and conductivity at infinite dilution of a solution (lambda 0), provides a measurement of the water-structuring activity of the solute. Measuring the effect of concentration on viscosity of solutions of amino acids, together with the conductivity of solutions of sodium chloride containing increasing concentrations of the amino acids, enabled Walden Products to be determined. The classical form of the Walden Product (lambda 0 eta 0) was used, together with a modified form, lambda 0 eta c, in which eta c was the slope of the concentration/viscosity curve. Most amino acids demonstrated modest water-structure-breaking activity but L-lysine, L-glutamic acid and L-aspartic acid, and their respective salts, all showed relatively higher activity. Dextrose behaved as a classical water-structure maker and, when added progressively, reversed the breaking activity of L-lysine. It is speculated that effects seen in bulk water may also occur at emulsion droplet surfaces, thereby inducing structural changes associated with the occasional rapid instability experienced when making admixtures of phospholipid-stabilized emulsions and additives such as amino acids and dextrose.

Amino Acids↗
PubMed1994

In-vivo and in-vitro targeting of a murine sarcoma by gelatin microparticles loaded with a glycan (PS1).

PS1, a complex polysaccharide derived from Mycobacterium bovis (Bacillus Calmette-Guérin, BCG) with considerable antitumor activity in-vivo, was loaded onto gelatin microparticles (mean diam. 1.45 micron) at a level shown to not produce the burst effect often seen with drug-loaded microparticulate systems. In-vitro dissolution experiments had demonstrated a sustained-release behaviour, with a half-life of approximately 8 h for what is an extremely water-soluble material. These PS1/gelatin systems had no measurable cytotoxicity against an S180 murine sarcoma cell in-vitro although fibronectin-mediated targeting of the microparticles for the tumour cells could be demonstrated. Injection into mice, with the S180 cells, of PS1 solutions or suspensions of PS1-loaded gelatin microparticles resulted in almost identical dose-related suppression for the tumour cell growth. When injected at intervals following injection of the tumour cells, however, for a period of 24-48 h there was a relatively enhanced activity of the formulated PS1, compared with the aqueous solution, after which both formulated and unformulated material became progressively less effective.

Animals↗
PubMed1994

Isolation of a fibronectin-binding tryptic peptide from the antigen 85A protein of Mycobacterium bovis BCG.

Antigen 85A, a major secreted mycobacterial fibronectin-binding protein, was isolated from culture fluids of the Tice substrain BCG vaccine. Tryptic digestion of this protein and passage of the digest through a fibronectin affinity chromatographic column resulted in the identification of a polypeptide fragment of molecular weight < or = 6.5 kD, which had marked fibronectin-binding activity. The identity of a 62-residue polypeptide was deduced from the amino-terminal sequence, indicating that the primary structure may define the integrin-binding capability.

Amino Acid Sequence↗
PubMed1994

Characterization of the antigen 85 complex fibronectin-binding proteins derived from aged culture filtrates of Mycobacterium bovis BCG, Tice substrain.

The antigen 85 complex are major T-cell and B-cell antigens and fibronectin-binding proteins secreted by Mycobacterium tuberculosis, M. leprae and attenuated M. bovis (BCG vaccine). The Ag 85 complex was found to comprise a high proportion of the extracellular protein in filtrates of surface-pellicle cultures of Tice-substrain BCG vaccine, attaining a maximum of 25%. This proportion began to decrease prior to the end of the logarithmic growth phase, about 3 weeks after the start of the culture, mainly due to apparent degradation of the Ag 85 complex. Isolation of the main Ag 85 protein and determination of the first 36 residues of the NH2-terminus showed identity with the 85A protein isolated by others from various mycobacteria. Both the Ag 85A and B components were secreted in nearly constant proportions over a 6-week period. No Ag 85C protein was detected.

Amino Acids↗
PubMed1993

Pharmaceutical characterization of Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine used for the treatment of superficial bladder cancer.

Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine, developed in the 1920s as a treatment and prophylactic for tuberculosis, has proved to be a nonspecific stimulant of the immune system and is now the major form of clinical immunotherapy approved for the treatment of superficial bladder cancer in the United States. However, methods for the production and physical characterization of the vaccine have not been significantly developed since Calmette and Guérin first devised their process for attenuating the organism in 1908. When reconstituted with sterile water immediately before use, the vaccine consists of a suspension of cellular fragments and aggregates and a mixture of dead and living cells. The dose is determined by the number of colony-forming units that develop when the vaccine is allowed to grow in a nutrient medium. This measurement of dose and viability is misleading because each cellular aggregate may consist of several hundred individual cells, but only one need be living to give rise to a single visible colony. Viability should therefore be measured on the basis of residual ATP levels. In this report, the mode of action of BCG vaccine against bladder cancer is reviewed, and attention is drawn to some factors that may need to be controlled during manufacturing and subsequent quality assurance procedures. The morphology of the various parts of the complex pleomorphic life cycle of this Mycobacterium species has been investigated, and the vaccine has been physically evaluated to provide a characterization by contemporary methodologies, including measurement of ATP content and particle size distribution of the dispersed mycobacterial aggregates.

Adenosine Triphosphate↗
PubMed1993

Properties of human albumin microparticles prepared by a chilled cross-linking technique.

Examination of conditions needed to form albumin microparticles (in the 1-5 microns diam. size range) by glutaraldehyde cross-linking, at low temperature (-15 degrees C), suggested that the particles formed very rapidly over a short time scale and at low concentrations of cross-linking reagent. Detailed analysis showed that the particles increased in size with time of reaction and with an increase in glutaraldehyde concentration. Evaluation of the particle matrix using a dilute trypsin digestion process suggested that the above factors may influence the internal composition since the particles dissolved less rapidly than might be anticipated from a consideration of particle diameter alone.

Albumins↗
PubMed1993

The redistribution of bulk aqueous phase phospholipids during thermal stressing of phospholipid-stabilized emulsions.

The mechanism of the stabilization of triglyceride emulsions by phospholipids has been studied using an HPLC-FID method to determine phosphatidylcholine, lyso-phosphatidylcholine and phosphatidylethanolamine in the oil and aqueous phases of a model emulsion consisting of soybean oil 20 g, egg phospholipid 1.2 g, glycerol 2.25 g and water to 100 mL. It was shown that, on heat sterilization of the emulsions, the phospholipids rapidly relocate from the aqueous phase to the oil phase. It is suggested that the phospholipids concentrate in the oil/water meso phase, forming a cubic liquid crystalline phase, the bulk of which is converted to a lamellar phase on cooling, and that this organization of interfacial material accounts for the enhanced stability of phospholipid emulsions after heat sterilization.

Chemistry, Pharmaceutical↗
PubMed1993

Inhibition of murine sarcoma cell adherence to polystyrene substrata by bacillus Calmette-Guérin: evidence for fibronectin-mediated direct antitumor activity of BCG.

Bacillus Calmette-Guérin (BCG) inhibited adherence of S180 mouse sarcoma cells and WI38 human diploid fibroblasts to the polystyrene substratum of 24-well cluster dishes in a dose-dependent manner. This property was retained by washed or heat-killed bacilli, but not by the vaccine filtrate or by the spent bacterial culture medium. Adhesion of bacilli to nonadherent S180 cells was demonstrated by light and scanning electron microscopy, but was not seen after trypsinization of adherent cells, indicating that bacilli bind to cell-surface adhesins. Preincubation of bacilli with human fibronectin abolished their ability to inhibit S180 adherence, suggesting that the phenomenon may be mediated by interaction of bacilli with cell-surface fibronectin. Fibronectin pretreatment of the bacteria also decreased their inhibition of S180 tumor growth in vivo, indicating that this mechanism may be at least partly responsible for BCG vaccine's observed antineoplastic activity.

Adsorption↗
PubMed1993

Phagocytosis of Mycobacterium bovis BCG organisms by murine S180 sarcoma cells.

Instillation of BCG vaccine directly into the bladder of patients suffering from superficial bladder tumours represents the major clinical application of this material. The mode of action is by no means clearly defined but it is known that the BCG cells need to be in close proximity to the tumours and may be capable of directly targeting the tumour cells through a fibronectin/fibronectin receptor interaction. In addition to cellular adherence there is a local stimulation of macrophages which is known to phagocytose mycobacteria. Use of a murine S180 sarcoma model facilitated the quantitative measurement of antitumour activity of BCG and BCG isolates. Ultrastructural examination of the BCG/sarcoma interaction confirmed that, in fact, these tumour cells do phagocytose and subsequently kill the BCG cells. The relationship between this phenomenon and the subsequent tumour cell death is not currently clear, although a strong tumoricidal agent has recently been isolated from BCG cells.

Animals↗
PubMed1992

Hydrolysis kinetics of phospholipids in thermally stressed intravenous lipid emulsion formulations.

A model 20% w/v emulsion, prepared with either a commercially available pharmaceutical grade soy oil or a highly purified grade of oil from the same origin and stabilized with a commercially available mixture of egg yolk phospholipids was passed through a Microfluidics homogenizer until the mean particle size fell below 500 nm diameter. Samples stored in sealed all-glass ampoules were thermally stressed over a temperature range of 5-90 degrees C and samples taken at appropriate intervals for analysis by HPLC. Hydrolysis degradation kinetics were in conformation with the Arrhenius equation. The energy of activation for phosphatidylcholine was virtually identical for emulsions prepared with either pharmaceutical or purified oil (65 and 63 kJ mol-1, respectively). For phosphatidylethanolamine itself the respective activation energies were 53 and 54 kJ mol-1, suggesting that the source of the oil used in preparing the emulsions had no significance in the degradation processes of the resulting systems.

Chromatography, High Pressure Liquid↗
PubMed1992

Origins of BCG surface charge: effect of ionic strength and chemical modifications on zeta potential of Mycobacterium bovis BCG, Tice substrain, cells.

The zeta potential of washed Tice substrain BCG organisms was measured over a range of ionic strengths from I = 0.005 to 0.1 M. No change in the isoelectric point of 3.4-3.7 was evident. Proteolytic enzymes (trypsin/chymotrypsin, pepsin, papain and pronase) and fluorodinitrobenzene abolished the cationic charge, suggesting that this is substantially due to amino groups associated with protein. Neither hot HCI nor cold trichloroacetic acid affected the charge, indicating that ionic groups are not associated with extractable polysaccharides. Methanolysis, treatment with HF and carbodiimide, and cationic detergent (cetyltrimethylammonium bromide) binding indicated that the negative charge was provided by carboxylic acids, phosphoesters and strong acidic groups, possibly sulphates. Standardless quantitative X-ray microanalysis revealed the presence of phosphorus and sulphur on the surface of actively growing BCG colonies.

BCG Vaccine↗
PubMed1991

A note on the use of topical digitalis prior to William Withering.

Attention is called to the fact that, long before the systematization of oral digitalis therapy by Withering in the eighteenth century, the drug was applied to the skin by inunction, producing effects that can now be recognized as due to an overdosage of Digitalis glycosides. The history of digitalis is briefly reviewed: the drug appears not to have been known to Greek and Roman physicians, but by the Middle Ages was widely used in folk medicine. Contrary to current wisdom, there is a wealth of historical information suggesting that topically applied Digitalis glycosides are capable of exerting physiological activity. It is perhaps time to re-examine this feature, in view of the present-day general interest in transdermal medications.

Administration, Topical↗