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Biomedical subjects

J F Norris

Publications and source records attributed to J F Norris.

At least 19 recordsLinked to original sources
PubMed1998

Differential response of sebaceous glands to exogenous testosterone.

To test the hypothesis that the seborrhoea of acne is an end-organ hyper-response to androgens, a standardized dose of 2% testosterone cream was applied to the forehead of eight prepubertal boys for 6 weeks and the effect determined by measurements of sebum excretion rate (SER). Three boys showed a 15-fold increase in SER and three boys were non-responders, whereas two boys had SER values between those of the responders and non-responders. These data show that sebaceous glands are stimulated by androgens to varying degrees and support the theory of an end-organ response in acne.

Acne Vulgaris↗
PubMed1995

Real-time compression of myoelectric data utilising adaptive differential pulse code modulation.

The myoelectric signal, obtained by either surface or needle electrodes, is used in many areas of clinical research and diagnosis. The conventional method of storing such information is in digitised form on a computer. However, the bandwidth of the signal and the required resolution result in large memory requirements. Adaptive differential pulse code modulation is investigated as a method of reducing the memory requirements for myoelectric data storage. In this scheme, a 12-bit sample is reduced to four bits, thus reducing the memory requirements by a factor of three. In reality, this compression ratio is closer to 4:1 owing to the fact that the widths of most memories are organised as multiples of eight bits.

Computer Systems↗
PubMed1994

A case of imported tungiasis in Scotland initially mimicking verrucae vulgaris.

A case is described of Tunga penetrans infection in the feet of a tourist returning from South America to Scotland. The condition had initially mimicked verrucae vulgaris, but microscopic examination of the lesions together with the travel history allowed the diagnosis of tungiasis to be made. This is the first case reported in Scotland.

Adult↗
PubMed1992

A double-blind evaluation of topical isotretinoin 0.05%, benzoyl peroxide gel 5% and placebo in patients with acne.

A double-blind, randomized study comparing isotretinoin gel (Isotrex), its vehicle base, and benzoyl peroxide was performed on 77 patients with mild to moderate acne vulgaris. The effect of treatment was assessed by acne grade and lesion count. The vehicle base had no effect, but both active groups produced significant improvements. Benzoyl peroxide and isotretinoin significantly reduced non-inflamed lesions at 4 (P < 0.05), 8 (P < 0.01), 12 (P < 0.01) weeks. Benzoyl peroxide had a more rapid effect on inflamed lesions, their being significant reductions at 4, 8 and 12 weeks (P < 0.01), whereas with isotretinoin there was a significant improvement at 12 weeks (P < 0.01). In addition, compared to placebo, both active treatments significantly reduced inflamed and non-inflamed lesions. Acne grade had improved significantly in the benzoyl peroxide group by 4 weeks (P < 0.01) and in the isotretinoin group by 8 weeks (P < 0.05). No significant change in haematological or biochemical parameters occurred. An irritant dermatitis occurred equally with both treatments but was well tolerated by the patients. This data confirms the clinical benefit of benzoyl peroxide in acne. The initial effect of isotretinoin on non-inflamed lesions in this study suggests that the prime mode of action is on comedone formation or separation whereas benzoyl peroxide has an effect on both comedones and inflammation.

Acne Vulgaris↗
PubMed1991

A comparison of the effectiveness of topical tetracycline, benzoyl-peroxide gel and oral oxytetracycline in the treatment of acne.

A proprietary topical tetracycline preparation (Topicycline) was compared with an alcohol-based 5% benzoyl-peroxide gel and with oral oxytetracycline (250 mg twice daily) using a randomized group-comparative double-blind study in 69 patients with mild to moderate acne. Facial acne grades improved significantly in all three treatment groups over the 12-week study period but chest acne grades did not change significantly and only oxytetracycline produced a significant improvement in back grade. All three treatment groups produced a significant reduction in facial inflamed and non-inflamed lesions apart from oxytetracycline which failed to produce a significant reduction in inflamed lesions. However, there were no overall significant differences between the three treatment groups either in improvement of acne grade or in reduction of inflamed and non-inflamed lesions. We conclude that topical tetracycline is as effective as either 5% benzoyl-peroxide gel or 250 mg oxytetracycline twice daily in the treatment of mild to moderate acne.

Acne Vulgaris↗
PubMed1988

A histological and immunocytochemical study of early acne lesions.

We examined 69 biopsies of acne lesions known to be 6, 24 or 72 h old and found that the lymphocyte was the predominant cell at 6 and 24 h. The helper:suppressor T cell ratio in the inflammatory infiltrate was 2.8:1. Polymorphonuclear leukocytes were increasingly seen at 24 and 72 h and were associated with disruption of the duct. We hypothesize that this early lymphocytic infiltrate represents a cell mediated immune response to an antigen within the duct lumen.

Acne Vulgaris↗
PubMed1988

Diphencyprone in the treatment of long-standing alopecia areata.

Thirty-six patients with alopecia areata of 1-54 years duration entered a study of treatment with the contact allergen diphencyprone for 8 months. Following sensitization the diphencyprone was applied to one half of the scalp at weekly intervals, the other half acting as a control. Once hair growth was established on one side, the other side was treated. Seven patients did not continue treatment and one patient showed spontaneous regrowth. Of the remaining 28 patients who persisted with treatments, fourteen (50%) regrew hair on the treated side; eight (29%) had a cosmetically acceptable result with the regrowth of terminal hair over the whole scalp. No statistically significant differences were found in age or duration of alopecia between those who regrew and those who did not. We have found diphencyprone to be an effective stimulator of hair growth in patients with severe and long-standing alopecia areata.

Adolescent↗
PubMed1987

Isotretinoin--an explanation for its long-term benefit.

Isotretinoin is of undisputed benefit in the treatment of acne. In doses of 1 mg/kg/day for 4 months the drug produces a highly significant reduction in sebum excretion rate (90 +/- 3%) in comedone formation as measured by assessing follicular casts (70 +/- 5%), and in surface Propionibacterium acnes. However, the mechanisms of long-term clinical remission are not well understood. There are however, risk factors which predetermine the outcome to treatment with isotretinoin. Younger subjects (14-19 years) and those who have had acne for less than 6 years, respond less well than older subjects. Subjects with more truncal acne also fare less well than those with predominantly facial acne. A return of the reduced sebum excretion rate to within 10% of the pre-treatment level also is a poor prognostic factor. This and future studies could lead to development of more logical dose regimes depending, for example, on the age of the patient; duration of acne and its site. However, until proven otherwise, this study confirms our earlier data, and that of the German multi-centres and Strauss et al (1), that the optimum dose schedule for treating acne patients is 1 mg/kg/day regime.

Acne Vulgaris↗
PubMed1985

Characterization and activity of phospholipase A2 in normal human epidermis and in lesion-free epidermis of patients with psoriasis or eczema.

The kinetic properties of phospholipase A2 isolated from single large specimens of normal human epidermis and 'uninvolved' (lesion-free) psoriatic epidermis were determined. The enzymes from the two sources behaved identically with respect to changes in protein concentration, Ca2+ concentration and pH, but the enzymes responded differently to changes in substrate concentration. Furthermore, the specific activity of the enzyme derived from lesion-free psoriatic epidermis was higher than that from normal epidermis under all conditions used. Increased specific activity of the enzyme in the lesion-free epidermis was also found when biopsy specimens taken from thirty-five patients with psoriasis vulgaris at varying severity were compared with biopsies of normal epidermis from thirty-one control volunteers (P less than 0.001). Mixing experiments, in which homogenates of lesion-free psoriatic epidermis and control epidermis were combined, suggested that the relatively low activity of the enzyme in normal epidermis was due to the presence of an inhibitor. As the activity of the enzyme was not elevated in the lesion-free epidermis from twelve cases of eczema, which is also an inflammatory condition of the epidermis and superficial dermis, it is suggested that the raised phospholipase A2 activity demonstrated in the lesion-free epidermis of psoriasis may play an important role in the pathogenesis of the disease.

Adolescent↗
PubMed1985

Neurofibromatous dermal hypoplasia: a clinical, pharmacological and ultrastructural study.

Dermal hypoplasia is reported in three patients with neurofibromatosis. The areas of dermal hypoplasia failed to react to vasodilator stimuli and responded poorly to a vasoconstrictor stimulus. Histology of these lesions showed neurofibromatous tissue and at an ultrastructural level cells resembling perineurial cells were wrapped around dermal vessels. The poor vascular responses seen in these areas of neurofibromatous dermal hypoplasia might be due to the perineurial cells acting as a barrier to diffusion of the pharmacological agents and as a physical perivascular splint.

Adult↗
PubMed1984

Utilization of epidermal phospholipase A2 inhibition to monitor topical steroid action.

The effect of several steroid creams on epidermal phospholipase A2 (PLA2) activity in symptomless psoriatic and normal epidermis was studied. The magnitude of PLA2 inhibition produced by the steroids was directly proportional to the initial level of the enzyme activity. This differential inhibition resulted in PLA2 activity approaching or attaining the normal range regardless of its initial level. Clobetasol propionate 0.05% (Dermovate) produced more enzyme inhibition than betamethasone valerate 0.1% (Betnovate) but there was no difference in inhibition between this latter steroid and clobetasone butyrate 0.05% (Eumovate). All were more inhibitory than hydrocortisone I% (Efcortelan).

Administration, Topical↗