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Biomedical subjects

P Wright

Publications and source records attributed to P Wright.

At least 235 records · Page 13Linked to original sources

Ophthalmic fluorophotometry: a new solid state fluorophotometer.

A new low-voltage ophthalmic fluorophotometer is described. A solid state photodetector has been combined with a high-gain, low-noise amplification and synchronous detection system to develop a stable, relatively inexpensive instrument. Reliable measurements of sodium fluorescein concentration in the eye can be made down to 100 ng/ml (0.26 mumol/l) which allows the estimation of corneal permeability and tear flow rates. Preliminary measurements of tear turnover rate using the fluorophotometer are presented.

Cornea↗

Evaluation of early excision of dorsal burns of the hand.

To determine the best method for treating deep second- and third-degree burned hands in our institution, a prospective study comparing early excision and grafting with nonsurgical treatment was undertaken. The patients were randomly assigned to two groups, and the hands in the first group were excised and grafted within 5 days after the burn. In the second group, burns were treated with topical chemotherapy and hydrotherapy, and the eschar was allowed to separate spontaneously and heal. Some required skin grafting, forming a subgroup. All hands in the study received the same vigorous physical therapy twice daily, and splints were applied according to the patient's individual needs to maintain an anti-deformity position. Grip strength, power pinch, and accurate range-of-motion measurements of each finger joint were measured upon discharge and 1, 2, 3, 6, and 12 months after the burn. A mean total degrees of motion (including flexion and extension) in each joint and strength values were determined for comparison among the three groups. At discharge, the spontaneously healed hands had the best range of motion and function. Although the rate of improved function was greatest in the interval from discharge to 6 months in all groups, by 1 year there was no statistical difference in function regardless of the initial treatment. Thus in deep second- and third-degree burns of the dorsum of the hand, care may be individualized according to other systemic factors without fear of sacrificing ultimate function.

Adolescent↗

Acute aortic stenosis of a porcine valve heterograft apparently caused by graft rejection: case report with discussion of immune mediated host response.

This report describes a patient with a gluteraldehyde preserved porcine xenograft in which acute prosthetic aortic valve stenosis developed during the postoperative period. Thrombotic occlusion was ruled out by direct visualization at reoperation, when a fibrin fusion of two leaflets was released to relieve the stenosis. After a fatal arrhythmia (79 days following insertion of the prosthesis), histological evaluation of the xenograft revealed a reaction on the leaflets, interpreted as predominantly transformed or blast lymphocytes. Microscopically, a thin layer of fibrin was visible over these cells. This fibrin layer could have stitched the commissure closed, producing the aortic stenosis. Such a sequence of events is unique in our past experience with 68 porcine xenograft valves. We believe that this case is an example of an immune mediated host response caused by rapid early fibrin fusion of prosthetic aortic leaflet margins, which resulted in prosthetic stenosis.

Journal Article↗

Schistosoma mansoni miracidial fluid inhibits human lymphocyte functions.

The hatching fluid from Schistosoma mansoni eggs collected from infected hamsters has been shown to inhibit the in vitro activation by mitogens of lymphocytes from healthy as well as infected hamsters. We have found that mitogen-induced activation of human cells was also inhibited by miracidial fluid (MF), as was specific stimulation induced by antigen or in the MLR. In addition, the cytotoxic activity of both K and NK cells was reduced in the presence of MF.

Animals↗

Preservative-related problems in soft contact lens wearers.

Details of 61 patients are presented who, having worn soft contact lenses for many months, developed red eyes, conjunctival irritation with minimal discharge, and progressive loss of tolerance of the lenses. Investigations revealed an absence of infective agents and the clinical course after treatment with preservative-free solutions strongly suggested that preservatives, especially organic mercurials, were responsible for the changes. The corneal signs were slow to clear but after resolution the majority of patients were able to return to soft contact lens wear using a heat disinfection system with preservative-free solutions. Skin testing to a wide range of substances, including preservatives, contact lens solutions, and common sensitizers, revealed only one responder to Thiomersal out of 21 tested. However a rapid response followed conjunctival challenge with 0.005 per cent Thiomersal in normal saline in all subjects tested.

Contact Lenses, Hydrophilic↗

The chemically injured eye.

Chemical injury of the eye may occur in a wide range of circumstances. Of first importance is the recognition of the nature of the injury since an increasing number of toxic substances is being used in home and industry and each type of compound may produce unusual corneal and conjunctival changes. Early assessment of the severity of the corneal burn helps determine prognosis and directs treatment. The use of topical sodium ascorbate and citrate has added new prospects of reduced corneal damage while enzyme inhibitors have shown some value in preventing and controlling corneal melting. The later problems of recurrent or persistent epithelial defects require careful manipulation of the tear film and corneal environment including the use of therapeutic soft contact lenses. In the long term, attention to the whole corneal environment, especially lids, conjunctiva, and tears, becomes most important especially in selection of patients for keratoplasty and in management of the complications which may follow surgery.

Alkalies↗

Blood pressure and hormonal changes following alteration in dietary sodium and potassium in young men with and without a familial predisposition to hypertension.

The blood pressures (BP) of the parents of a group of students were determined and two subgroups of students were defined, one with (PHT group) and one without (PNT group) a familial predisposition to hypertension. Observations were made in both groups during three periods of modified dietary electrolyte intake: (i) no-added sodium (low Na), (ii) no added sodium with potassium supplementation (low Na/high K), and (iii) sodium supplementation (high Na). The diets were given in random order. At the start of the trial, while the students continued their customary diet, the PHT group had higher systolic and diastolic pressures and plasma noradrenaline levels than the PNT group. At the end of 4 weeks of the high Na diet, the BP levels of both groups were significantly higher than those after the low Na diet. In contrast, when the low Na diet was supplemented for 2 weeks with potassium, BPs of the PHT group fell significantly, while those of the PNT group rose slightly. BP in the PHT group was significantly lower during the low Na/high K than during the high Na diet (systolic 10.5 mm Hg +/- 2.3 SE; diastolic 11.2 +/- 2.5, the changes being significantly different from those in the PNT group. The changes in plasma renin and aldosterone were similar in both groups during the different diets. Plasma noradrenaline fell in the PHT group, but rose in the PNT group when the low Na diet was supplemented with potassium. This fall in plasma noradrenaline in the PHT group during the low Na/high K diet correlated with the falls in systolic and diastolic BP. It is concluded that whereas young adults with a familial predisposition to hypertension behave similarly to those without such a predisposition in having a pressor response to a high sodium intake, they are peculiar in showing a depressor response to a high potassium intake.

Adult↗

"The instructions clearly state ..." Can't people read?

Understanding and complying with the instructions that accompany consumer products is not always easy, and indeed people may ignore the instruction entirely. Designing adequate instructions is a complex task. The basic requirements for good instructions can be specified, but the problem is one of developing adequate design procedures to meet them. Such procedures will involve co-ordinating the skills of experts in verbal and graphic communication, as well as those of experts familiar with the research literature and with techniques of empirical evaluation. The consequences of poor instructions can be serious. Moreover, changes in the legal notion of product liability may encourage manufacturers to re-examine how their instructions are prepared.

Journal Article↗

Antituberculosis activity of 6 cyclo-octylamino-5,8-quinolinequinone (CQQ).

A new compound, 6 cyclo-octylamino-5,8-quinolinequinone (CQQ), a dual analogue of vitamin K and coenzyme Q, was effective against several drug-susceptible and drug-resistant strains of Mycobacterium tuberculosis. In vitro studies indicated the bactericidal nature of its action at 1 microgram/ml. Pulse exposure studies using M. tuberculosis H37Rv showed that a growth lag period of 96 hours resulted with exposure to 1 microgram/ml for 24 hours or longer.

Mycobacterium tuberculosis↗

Antagonism within populations of micro-organisms from normal human skin.

The skin flora of 20 normal subjects was sampled from 7-cm2 sites on the volar forearm, forehead and ball of the foot. Interactions between all aerobic and anaerobic strains isolated from the same site were examined by a deferred-antagonism technique. Seventeen subjects possessed inhibitory strains on at least one skin site. Of the Micrococcaceae tested, 20.6% were inhibitory. Of the aerobic diphtheroids, more strains were sensitive (19.2%) than inhibitory (5.1%). Inhibitory Micrococcaceae and aerobic diphtheroids revealed intergeneric and intrageneric inhibition. Antagonistic propionibacteria were found (7.4%) but no sensitive strains. Several Micrococcaceae were specifically antagonistic towards only one strain isolated from the same skin site; no sensitive strains from other skin sites or other subjects were found. Quantitative sampling showed that only 17.5% of the inhibitory strains clearly dominated their skin sites numerically.

Adult↗

The masquerade syndrome.

Malignant lesions of the lid and ocular adnexae may present with striking inflammatory signs and this has most often been described with meibomian gland carcinoma and given the name of the masquerade syndrome. This paper presents examples of lid malignancies which have not only masqueraded as predominantly inflammatory lesions but whose origin was further obscured by the nature of the spread of the tumour in lid and conjunctiva. Recognition of the true nature of the malignancy only follows biopsy of the centre of the lesion which is fully justified in an older patient presenting with unilateral chronic, unresponsive inflammation especially involving the canthus and bulbar conjunctiva as well as the lid. Histological confirmation of the nature of the peripheral spread of the tumour is also of importance since pagetoid spread has been shown to be associated with more aggressive neoplasia and increased mortality.

Aged↗