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Biomedical subjects

B L Diffey

Publications and source records attributed to B L Diffey.

At least 109 records · Page 6Linked to original sources
PubMed1988

Light and length of stay in hospital.

A study was carried out to examine whether the time spent as an inpatient in hospital showed a seasonal dependence which could be attributed to differences in ambient lighting levels between summer and winter. It was found that the season of admission to hospital did not make any appreciable difference to how long patients took to recover before they were discharged.

Hospitals↗
PubMed1988

Treatment of solar urticaria with terfenadine.

Treatment with the H1 receptor antagonist terfenadine increased significantly the dose of radiation required for weal and flare formation in 5 patients with idiopathic solar urticaria. The dose of radiation required to produce immediate erythema localised to the irradiation site was unchanged by terfenadine. The weal and flare reaction in solar urticaria, but not the immediate erythema, is mediated by histamine acting on the H1 receptor.

Adult↗
PubMed1988

Ambient ultraviolet radiation and skin cancer incidence.

Environmental ultraviolet radiation (UVR) was monitored for one year at Durham (latitude 55 degrees N) using a stationary, horizontal sensor, and a sensor rotating in a vertical plane designed to simulate the random motion of subjects outdoors. From these data it was possible to calculate the personal solar UVR representative of populations living at different geographical locations and experiencing varying patterns of cloud cover. The conclusion was that present monitoring programmes that record ambient solar UVR in a horizontal plane at different locations as input data to studies on the epidemiology of skin cancer are appropriate for obtaining a relative estimate of the population exposure in locations with different climatic conditions, providing, of course, that the outdoor exposure habits of different populations are comparable.

Environmental Monitoring↗
PubMed1988

[Is accurate UVA dosimetry in photobiology and photodermatology an illusion?].

Accurate UVA dosimetry is of primary importance for photobiological research as well as for UVA phototherapy and photochemotherapy. For the former, it is necessary because the success or failure of an experiment can depend on the UVA dose, and for the latter, the carcinogenic risks are dependent upon the cumulative dosage, as is the evaluation of the therapy. Experience has shown that the UVA meters used in different photodermatological and photobiological centers give divergent values when exposed to the same UVA source. One Joule/cm2 does not seem to be the same thing everywhere, and it can vary by as much as 400 p. 100.

Humans↗
PubMed1987

Phototherapy and dithranol treatment of psoriasis: new lamps for old.

The response of psoriasis to ultraviolet radiation and dithranol was compared with the response to dithranol alone in 24 patients. The difference in rate of response, measured as change in plaque thickness, and the difference in time to complete clearance of psoriasis between irradiated and non-irradiated forearm lesions was significantly greater for patients treated using fluorescent lamps with negligible ultraviolet C emission (Wolff Helarium) than for those patients treated with a medium pressure mercury arc lamp (p less than 0.01) or an array of fluorescent sunlamps (p less than 0.05). The difference in therapeutic response shows that ultraviolet B phototherapy is effective when used in combination with dithranol. Nevertheless, radiation sources with substantial ultraviolet C emission, such as the medium pressure mercury arc lamp most commonly used to treat psoriasis in the United Kingdom, have little effect because delivery of therapeutic doses of ultraviolet B is limited by erythema induced by ultraviolet C.

Adolescent↗
PubMed1987

Quantitative studies on UVA-induced erythema in human skin.

The erythemal response of normal human skin to UVA and UVB radiation was measured objectively using a reflectance instrument in seven subjects, and a laser Doppler velocimeter in two subjects. UVA radiation was produced using a newly-developed high-intensity UVA lamp. The slope of the log dose-erythemal response curve for UVA at 24 h after irradiation was found not to differ significantly from that for UVB. The time course of UVA erythema was biphasic; erythema was present immediately after irradiation, fell to a minimum at about 4 h and then rose to a broad plateau between 6 and 24 h. The intensity of the early phase was dose-rate dependent, whereas that in the later phase depended on dose only.

Adult↗
PubMed1987

Photodermatitis due to spot welding.

The case of a patient with a 1-year history of recurrent, severe facial dermatitis is reported. The role of ultraviolet radiation from arc welding or other equipment at work in inducing dermatitis is discussed.

Adult↗
PubMed1987

The onset of ultraviolet erythema.

The onset of erythema induced by UVB and by UVC radiation was monitored in two subjects using a reflectance instrument. It was shown that vasodilation occurred some time before erythema became visible, even with small exposure doses of UVB or UVC, after which visible erythema was not apparent for several hours. In one subject, vasodilation was detected very shortly after irradiation and may have even begun during irradiation. In the other subject vasodilation was detected later at most exposure doses, but still some time before erythema became visible. We conclude that the so-called 'latent period' between irradiation and appearance of erythema is an artificial concept arising from the insensitivity of the eye.

Dose-Response Relationship, Radiation↗
PubMed1987

A comparison of dosimeters used for solar ultraviolet radiometry.

Radiometric measurements of terrestrial sunlight using three different types of broad-band dosimeters were compared with equivalent integrated quantities obtained from simultaneous spectroradiometric measurements. Measurements were made at Durham, UK (55 degrees N) during one day in mid-summer and one day in the autumn. By this means it was possible to encompass a wide range of ultraviolet irradiances. There was close agreement between UV-A irradiance measured using a broad-band radiometer and determined spectroradiometrically over the whole range of irradiances when allowance was made for the spectral sensitivity of the UV-A radiometer. The agreement between erythemally-effective irradiance determined spectroradiometrically and the response of a Robertson-Berger meter showed some non-linearity due to the mismatch between the erythema action spectrum and spectral response of the sensor. There was a similar disparity in agreement between erythemally-effective dose determined spectroradiometrically and the response of polysulphone film for similar reasons. Nevertheless it is concluded that if these latter two dosimeters are calibrated using sunlight, or a solar simulator, as the source, they can yield data which are sufficiently reliable for many applications.

Radiation Dosage↗
PubMed1987

Evaluation of subjective assessment of liver function from radionuclide images.

The appearance of non-hepatic uptake in 99Tcm-colloid images is an important indicator of poor liver function. We undertook this study to evaluate the ability of experienced observers to assess liver function from radionuclide images. A simple model was used to simulate the changing distribution of 99Tcm-colloid in the liver, spleen and bone marrow as the liver function and mass were varied. Suitable images of these three organs were isolated from real studies and used as "templates" to create realistic simulated 99Tcm-colloid images, with the count densities of liver, spleen and bone marrow determined by the model. These images were presented in random order to several observers, who were asked to assess liver function. Comparison of the estimated with the true function shows that visual assessment is systematically inaccurate, with underestimation of poor function and overestimation of good function. It is also imprecise, especially for livers with only midly impaired function. Observers were also affected by changing liver mass and were more likely to judge small livers to be abnormal. We suggest that objective assessment using a quantitative technique should be used as an adjunct to visual inspection for the evaluation of liver function.

Humans↗
PubMed1987

PUVA-induced blisters, complement deposition, and damage to the dermoepidermal junction.

We followed the course of 56 patients receiving psoralen plus long-wave ultraviolet light (PUVA) therapy. Nonhemorrhagic blisters developed on clinically normal skin on the limbs of seven patients. Seeming to be related to friction and trauma, the blisters form as a result of damage to the basal and suprabasal layers. Perilesional skin specimens from all blistered patients contained granular deposits of C3 at the dermoepidermal junction, around the upper dermal blood vessels, or at both sites. The average time for initiation and complete formation of suction blisters was measured in 51 patients at different stages during the course of PUVA treatment. Blister separation was in the lamina lucida, with the pemphigoid antigen in the roof while the blister floor contained the lamina densa, laminin, and type IV collagen. This impaired dermoepidermal adhesion was a general phenomenon that occurred in all PUVA-treated patients. The mechanism remains to be determined.

Adult↗
PubMed1987

A new type of erythemal radiometer for use in phototherapy.

A new type of radiometer is described which, when exposed to ultraviolet radiation lamps, displays the time required to achieve a minimal erythema. The radiometer incorporates a switch on the front panel to allow for the erythemal sensitivity of different sun-reactive skin types. The instrument was exposed to a number of different lamp/filter combinations commonly used for phototherapy, and in each case indicated an exposure time to within +/- 10% of that determined by combining the spectral irradiance with the erythema action spectrum. Good agreement was also obtained between the exposure times necessary to achieve 24 h minimal erythema in Caucasian subjects of different sun-reactive skin types, and those exposure times predicted by the erythemal radiometer.

Erythema↗
PubMed1987

PUVA lentigines.

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Dose-Response Relationship, Radiation↗