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Biomedical subjects

J E Rees

Publications and source records attributed to J E Rees.

At least 19 recordsLinked to original sources
PubMed1991

Wernicke-Korsakoff syndrome of nonalcoholic origin.

We describe a patient who developed a severe loss of memory following intravenous feeding and intestinal surgery. The pattern of both anterograde and retrograde memory impairment and frontal pathology is shown to be comparable with that observed in patients with Wernicke-Korsakoff Syndrome of an alcoholic etiology. The data strengthen the view that the essential characteristics of the Wernicke-Korsakoff Syndrome are not dependent on a prior history of chronic alcoholism. Implications of these data for the interpretation of alcoholic Wernicke-Korsakoff Syndrome are considered.

Adult↗
PubMed1989

The use of a biological adhesive to achieve sutureless epikeratophakia.

An adhesive made of concentrated human fibrinogen produced from samples of single donor blood by a simple cryoprecipitation method was tested for its ability to bond lamellar corneal buttons in vitro and found to have a bond strength of 140 gm/cm2. The adhesive was successfully used to attach experimental epikeratophakia grafts in a rabbit model. The results were similar to those reported from an earlier trial using a commercially available adhesive prepared from pooled multi-donor human plasma. This experimental trial of single-donor adhesive demonstrates the possibility of successful use of autologous fibrinogen adhesive in human epikeratophakia. Autologous adhesive would remove the possible threat of transmitted disease posed by multi-donor adhesive and avoid immune reactions to foreign proteins.

Animals↗
PubMed1988

Experimental epikeratophakia with biological adhesive.

Successful experimental epikeratophakia grafting was done with the use of a biological adhesive. The use of an adhesive eliminated the need for any suturing of the corneal lenticule to the host cornea, and this method reduced the length of the operative procedure to only one third of the time that is taken when sutures are used. Tisseel (Immuno AG, Vienna), a commercially available two-component adhesive system based on human fibrinogen, which is activated by thrombin, was used. The glue was used in combination with an antifibrinolytic agent. With alteration of the operative technique and lenticule design, 70% of glued epikeratophakia grafts in a rabbit model were retained, compared with a 50% success rate with grafts applied without the use of an adhesive.

Animals↗
PubMed1985

Malignant optic nerve gliomas in adults.

Two patients with malignant optic nerve gliomas are described. The clinical courses and radiographic appearances are discussed, with emphasis on the fact that this condition should be considered in the differential diagnosis of rapid visual failure. It can now be strongly suspected preoperatively on the basis of computed tomographic scan appearances.

Adult↗
PubMed1983

Segregation of vibrated powder mixes containing different concentrations of fine potassium chloride and tablet excipients.

The effect of different drug/excipient concentrations on the segregation tendency of three ordered powder mixes was studied. In addition, the influence of vibration frequency on the segregation intensity and mechanisms of segregation was also studied. Differences in content uniformity of the powders were measured by comparing samples from regions at different depths between the upper exposed powder surface and the base of the cylindrical container. Ordered mixes containing recrystallized lactose excipient and fine-particle potassium chloride as a model drug were found to be least susceptible to segregation at most vibration conditions for all potassium chloride concentrations. Dipac excipient/potassium chloride particles were most susceptible to segregation under all test conditions. In general, segregation intensity was most marked in conditions where high potassium chloride concentrations, above 2% w/w, were subjected to low-frequency vibration, below 100 Hz. Segregation mechanisms were considered to be mainly dependent on vibration conditions, although carrier excipient type markedly modified mechanisms and influenced segregation intensity.

Drug Compounding↗
PubMed1983

Psychophysical assessment of a patient with Tolosa-Hunt syndrome.

Patients may complain of impaired vision and yet exhibit no abnormalities when tested with conventional tests of visual acuity. Some sensitive psychophysical tests used by psychologists and neurophysiologists to examine the function of the normal visual system are beginning to gain recognition as useful tools in clinical situations. They are particularly sensitive indicators of damage to the visual pathways. The results are presented of one such application which characterises the visual defects of a patient with a suspected diagnosis of Tolosa-Hunt Syndrome.

Discrimination Learning↗
PubMed1982

Electrostatic charge interactions in ordered powder mixes.

A method is described for measuring the electrostatic charge generated in powders following contact with a plane substrate. The method uses a Faraday well connected to an electrometer and allows the specific charge of powders to be determined. Of the various drugs and excipients studied, most charged electronegatively following contact with glass surfaces, but became electropositive after contact with polyethylene surfaces. The charge interactions of drug and excipient powders modified the behaviour of ordered mixes formed in similar conditions to those of charge measurement. Powders with like charges formed less stable ordered mixes than those in which drug and excipient particles carried opposite charges. Following triboelectrification in an air cyclone constructed of brass, powders had charges at least 100 times greater than those formed after contact with glass surfaces. Optimization of the triboelectric charging conditions allowed ordered mixes to be prepared in which a maximum electronegative charge was applied to the excipient whilst the drug was given a maximum electropositive charge. Studies of segregation/stability showed that ordered mixes subjected to triboelectrification were less prone to segregation than uncharged powders.

Drug Compounding↗
PubMed1982

Interparticle forces in binary and ternary ordered powder mixes.

An ultracentrifuge technique, previously described by Staniforth et al (1981), has been used to study the adhesion profiles of several binary and ternary ordered powder mixes of pharmaceutical interest. The adhesion profile of an ordered mix provides information about the proportion of drug powder adhering with different forces of attraction to the carrier excipient particle surface. The excipient particle size is shown to affect adhesion between the components of a binary ordered mix-recrystallized lactose formed more stable ordered mixes with drug powder when the carrier particle size was increased. Changes in the adhesion profile of each binary system on adding three different fine-powder excipients to form a ternary ordered mix are also examined. The physical properties of carrier particles and the charge interactions of a third powder component with previously formed binary ordered mixes, are found to influence the physical stability of ternary ordered mixes.

Adhesiveness↗
PubMed1982

Effect of vibration time, frequency and acceleration on drug content uniformity.

The effect of different vibration conditions on the segregation tendency of three ordered powder mixes was studied. Segregation of the powders was measured using a cylinder, composed of interlocking units for sampling purposes, mounted on a vibration rig. Ordered mixes containing either Emdex or recrystallized lactose carrier particles mixed with 0.5% fine-particle potassium chloride were stable, except for slight segregation that occurred under severe vibration conditions at frequencies below 50 Hz and accelerations above 22 m s-2. Powder mixes of Dipac with potassium chloride were unstable at most vibration conditions from 20 to 1000 Hz and 7.4 to 29.4 m s-2. The intensity of segregation in vibrated mixes of Dipac with potassium chloride was most marked at frequencies below 50 Hz and accelerations above 22 m s-2. These vibration conditions were found to occur in several commonly-used types of tableting presses. When vibration was prolonged, for periods of 30 to 60 min, there was increased segregation found in ordered mixes.

Drug Compounding↗
PubMed1978

Time-dependent deformation of some direct compression excipients.

Three techniques were used to compare the time-dependent deformation of microfine cellulose (Elcema G250), anhydrous lactose, dicalcium phosphate dihydrate (Emcompress), modified starch (Sta-Rx 1500) and sodium chloride. (1) In stress-relaxation experiments using a reciprocating tablet machine, none of the materials behaved as a Maxwell body in contrast to recent published work (David & Augsburger, 1977). Possible reasons for this disagreement are discussed. (2) Heckel plots showed that increasing the time for which a material was under compression (contact times of 0.17 and 10 s) had no effect on dicalcium phosphate compacts but increased the consolidation of other materials in the rank order sodium chloride less than lactose less than cellulose less than starch. (3) Deformation tests on preformed compacts were carried out in diametral compression by loading compacts to 75% of their breaking force at four different strain rates between 0.05 and 6.5 mm min-1. The deformation of Sta-Rx compacts was time-dependent. Sodium chloride compacts exhibited brittle behaviour in the diametral compression test and in the 10 s contact time experiment. This was apparently due to work-hardening, following the extensive plastic deformation of crystals during compaction as indicated by the stress relaxation results.

Chemical Phenomena↗