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Biomedical subjects

S B Murray

Publications and source records attributed to S B Murray.

12 recordsLinked to original sources
PubMed1998

The role of pH, temperature and nucleation in the formation of cholesteric liquid crystal spherulites from chitin and chitosan.

The alpha chitin and chitosan used in the experiments came from crab shell waste (Sigma). This was treated to form a colloidal suspension of chitin or chitosan crystallites. The electrostatic 'charge coat' surrounding the chitin was then manipulated. This was achieved by alteration of the pH of the chitin or chitosan colloid (Chitin pKa = 6.1). This allowed the charge density on the crystalline rod of chitin or chitosan to be altered. The effect of this treatment was ascertained by measuring the diameter of spherulites formed in vitro. The results were analysed to see if the experimental optimal pH agreed with theoretical approximations. Further investigations were carried out on the initiation of the spherulites and the effect of temperature on spherulite formation. The spherulites form via self assembly through a liquid crystalline cholesteric phase. Manipulation of the electrostatic coat of the chitin could be a method of cellular remote control for formation of the helicoid in arthropod cuticle. This would allow the arthropods to set up conditions that aid the self assembly process.

Chitin↗
PubMed1997

The role of the electrostatic coat in the formation of cholesteric liquid crystal spherulites from alpha-chitin.

The alpha-chitin used in the experiments came from crab shell waste. This was boiled in 3M HC1 to form a colloidal suspension of chitin crystallites. The electrostatic 'cost' surrounding the chitin was then manipulated in two ways. The first was the alteration of the pH of the chitin colloid (Chitin pKa = 6.1). This allowed the charge density on the crystalline rod of chitin to be altered. The second way was to alter the background charge in the environment by adding salt solutions to the colloid. The effect of the treatments was ascertained by measuring the diameter of the spherulites formed in vitro. These spherulites formed via self assembly through a liquid crystalline cholesteric phase. Raising the pH (within limits), resulted in larger spherulites. Raising the background charge also gave larger spherulites (within limits). As such both background charge and charge on the rod can be used to control the self assembly of the cholesteric spherulites. Manipulation of the electrostatic coat of the chitin could be a method of cellular remote control for formation of the helicoid in arthropod cuticle. This would allow the arthropods to set up conditions that aid the self assembly process.

Animals↗
PubMed1993

Treatment of reflux esophagitis resistant to H2-receptor antagonists with lansoprazole, a new H+/K(+)-ATPase inhibitor: a controlled, double-blind study. Lansoprazole Study Group.

This multicenter, randomized, double-blind, 8-wk study compared the new H+/K(+)-ATPase inhibitor, lansoprazole, 30 mg daily, to ranitidine 150 mg bid for treatment of erosive reflux esophagitis resistant to histamine-2 receptor antagonists (H2RA). Patients were evaluated after 2, 4, 6, and 8 wk of treatment by symptom assessment and endoscopy. Healing rates for lansoprazole were 71%, 80%, 88%, and 89% at 2, 4, 6, and 8 wk, respectively, compared to 21%, 33%, 45%, and 38% for ranitidine (p < 0.001 at all points). Lansoprazole was significantly more effective than ranitidine for relief of heartburn and reduction of antacid tablet use. Increases in serum gastrin concentrations between the baseline and the 8-wk visit were greater in lansoprazole-treated than in ranitidine-treated patients. Lansoprazole was safe and well tolerated. In patients with erosive reflux esophagitis resistant to standard doses of H2RA, lansoprazole 30 mg/day is more effective than continuation of an H2RA (ranitidine 150 mg bid) for healing of esophagitis and improvement of symptoms.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1992

Spontaneous subconjunctival haemorrhage--a sign of hypertension?

The relationship between the condition of spontaneous subconjunctival haemorrhage (SCH) and hypertension was investigated. Seventy eight patients with SCH and 78 controls with unrelated ophthalmic conditions were compared. Blood pressure (BP) was significantly higher at presentation in the group with SCH at 149 (SD 27)/89 (SD 15) versus 142 (SD 25)/81 (SD 12). The proportion of hypertensives by WHO criteria (systolic blood pressure > 160 and/or diastolic blood pressure >95) was 46% on presentation compared with 23% of the control group. The morphology of the lesion did not influence the association with hypertension although there was a suggestion that the group with raised haemorrhages had a tendency to higher systolic blood pressure. It is recommended that all patients with SCH have their BP checked; this will result in the diagnosis of a significant number of new hypertensives.

Adolescent↗
PubMed1988

Early trabeculectomy versus conventional management in primary open angle glaucoma.

The results of a randomised, prospective, multicentre trial of the management of primary open angle glaucoma are presented at up to five years' follow up. Previously undiagnosed cases were selected with intraocular pressure of 26 mmHg or more on two occasions together with field loss characteristic of glaucoma. Analysis was performed on one eye selected at random from each of 99 patients. Conventional medical treatment followed in unsuccessful cases by trabeculectomy (group A) was compared with trabeculectomy at diagnosis followed when necessary by supplementary medical therapy (group B). The life expectancy of these glaucoma patients was found to be similar to that for the local population matched for age and sex. In group A after four years trabeculectomy had been performed in 53% of eyes because medical management had failed to control the disease. The rate of operation was lower in those patients with intraocular pressure less than 31 mmHg and mild relative field loss (17% at three years) than in those with intraocular pressure greater than 30 mmHg and dense scotomas (75% at three years). Early surgery provided much more stable control with fewer changes in treatment than in group A. The group mean intraocular pressure after trabeculectomy was 15.0 mmHg irrespective of the time of operation, and this was significantly lower than the intraocular pressure in those cases thought to be controlled on medical therapy alone at the end of the first year (20.8 mmHg). Early operation provided significantly better protection of visual field, and the extra loss of visual field with delayed operation occurred in the preoperative period. Changes in visual fields were not related to the use of miotics. There was no significant difference in the final visual acuity in the two groups, but six cases in group A lost central fixation because of progressive loss of visual field, and there were no such cases in group B. Cataract occurred in approximately 10% of cases in both groups, but in group A this happened with only half the number of operations and at a shorter postoperative follow-up than in group B. It appears that in cases of primary open angle glaucoma of this severity the risk of delaying operation are significantly greater than those of performing trabeculectomy as the primary treatment.

Aged↗
PubMed1984

Senile atrophy of the human lacrimal gland: the contribution of chronic inflammatory disease.

Histological examination of 99 human lacrimal glands showed a relationship between atrophy of the secretory acini and secretory duct obstruction, ascending periductal fibrosis, and obliteration of the adjacent blood vessels caused by lymphocytic and polymorphonuclear inflammation. Investigation of the subgroups of the B lymphocytic series by immunohistochemistry did not show any statistical change with age, sex, fibrosis, or lymphocytic inflammation. The concept of senile atrophy occurring as a result of senescent involution of the lacrimal gland is challenged on the basis of the histological findings.

Adolescent↗
PubMed1982

Keratoconjunctivitis artefacta.

Six cases of keratoconjunctivitis caused by self-inflicted injury are described. The diagnosis is suggested by the combination of the characteristic sharply delineated lesions localised in the more accessible inferior and nasal quadrants of the bulbar conjunctiva and cornea, together with the unconcerned attitude of the patient and other psychological features. Secondary post-traumatic erosions, infections, and allergies may complicate the clinical appearances, and other functional eye disturbances including corneal anaesthesia may be detected. In all cases the eye condition resolved with a sympathetic but authoritative approach avoiding direct accusation. Avoidance of feelings about bereavement or sexual relationships were directly related to the onset of symptoms in 3 cases. In some patients the psychological mechanism seemed inaccessible and they continued to produce new self-inflicted diseases with considerable physical and psychological morbidity. These more intractable cases need psychiatric investigation but usually resist referral.

Adolescent↗
PubMed1981

Human conjunctival surface mucins: a quantitative study of normal and diseased (KCS) tissue.

The architecture and distribution of surface mucins were studied qualitatively and quantitatively by transmission electron microscopy in ruthenium red stained biopsies of the human conjunctiva. Six control specimens were compared with three from early keratoconjunctivitis sicca (KCS) and with three specimens from severe KCS cases. The area of the ruthenium red/OsO4/mucin reaction product on the conjunctival epithelial surface was measured by image analysis and the values were expressed in micron2 per micron length of epithelium. The total area of surface mucins was differentiated from the narrow zone of mucins in close contact with the microplicae. The value for total mucins in two cases of early KCS was higher (0.4 micron2/micron) than the control range (0.1-0.3 micron2/micron) due to the presence of large clumps of mucins on the surface. The values for microplical mucins in early and severe KCS were within the control range, but were an overestimate owing to the presence of abnormal structures, e.g. vesicles, and abnormal clumps on the surface. This morphometric technique has limitations, but with appropriate material it might be a useful tool for the identification of conjunctival surface mucins.

Aged↗
PubMed1980

Characteristics of reduction of intraocular pressure after trabeculectomy.

The change in intraocular pressure achieved after 98 trabeculectomy operations performed on 70 patients with primary open-angle glaucoma was analysed. The reduction was proportional to the untreated preoperative pressure, and the results indicated that a first trabeculectomy reduced the intraocular pressure to between 16 and 20 mmHg irrespective of its initial level. Cases which required medical therapy for final pressure control after surgery showed a distribution of initial intraocular pressure similar to those not requiring such therapy. In addition, these cases were reduced to a level of pressure only slightly above the arbitrary figure of 20 mmHg before medical therapy was added, and were therefore considered almost to have reached the normal physiological range. Cases submitted to a second trabeculectomy are discussed, including 2 cases with unexplained acute open-angle glaucoma some months after the first operation.

Female↗
PubMed1979

Trabeculectomy. Its role in the management of glaucoma.

This report describes the changes in intraocular pressure, visual fields, and visual acuity after 108 trabeculectomy operations for various types of glaucoma. Postoperative follow up ranged from 1 1/2 to 3 years and the consequences of any complications were assessed. Trabeculectomy was found to be a relatively safe and effective procedure and may be recommended at an early stage in glaucoma management rather than as a last resort.

Glaucoma↗
PubMed1979

Acute posterior multifocal placoid pigment epitheliopathy: not so benign?

A case is described of acute posterior multifocal placoid pigment epitheliopathy (APMPPE) in which one eye shows the typical active disease process while the other shows evidence of extensive degenerative changes of the posterior pole with disturbance of the pigment epithelium. It is postulated the case presented shows that APMPPE may not be as benign a condition as previously thought, and that it may recur after a period of years.

Acute Disease↗