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Biomedical subjects

R S Barnetson

Publications and source records attributed to R S Barnetson.

At least 19 recordsLinked to original sources
PubMed2001

Treatment of refractory hand warts by isolated limb infusion with melphalan and actinomycin D.

We present an immunocompetent man with extensive warts on the hands, refractory to a number of conventional treatment modalities and causing substantial morbidity and impairment of normal function. Isolated limb infusion (regional intra-arterial chemotherapy) with melphalan and actinomycin D was performed, with substantial clearing of the warts within 2 months. Treatment-induced morbidity was limited to mild local erythema and oedema which resolved within 3 weeks. After 9 months' follow up, the patient had only a few residual warts and was able to resume normal activities.

Adult↗
PubMed2001

Effects of low-dose ultraviolet radiation on in vivo human cutaneous recall responses.

Relatively few studies have examined the effects of low-dose ultraviolet (UV) radiation on in vivo human cutaneous immunity, or the ability of sunscreens to prevent UV-induced immunosuppression. We have studied the effects of solar-simulated UV radiation on nickel contact hypersensitivity (CHS) in nickel-allergic volunteers, and on delayed type hypersensitivity responses in Mantoux-positive volunteers. Nickel CHS and Mantoux responses were significantly suppressed by acute, suberythemal UV exposures equivalent to less than 8 min summer sunlight. Both UVA and UVB wavebands were immunosuppressive, but UVA-induced immunosuppression was transient, whereas UVB had a more sustained effect. Dose-responses for UV immunosuppression were determined using the nickel method, enabling calculation of in vivo sunscreen immune protection factors in a manner analogous with sun protection factor measurement. Sunscreens were found to confer significantly less protection against UV-induced immunosuppression than against UV-induced erythema.

Allergens↗
PubMed2000

Cytokine profiles in spontaneously regressing basal cell carcinomas.

BACKGROUND: Basal cell carcinomas (BCCs) can cause considerable morbidity due to their ability to enlarge progressively and to destroy underlying tissues. However, some BCCs may undergo spontaneous regression in the absence of therapy capable of inducing antineoplastic effects. Histological criteria for this process have been described, and previous studies have suggested that it may be mediated by infiltrating activated CD4-positive T cells. OBJECTIVES: The purpose of this study was to compare the expression of cytokines in actively regressing and non-regressing BCCs, to ascertain if active regression is associated with a particular cytokine profile. METHODS: Reverse transcriptase-polymerase chain reaction, a sensitive, quantitative technique allowing analysis of multiple cytokines from small tumour samples, was used. RESULTS: Interferon (IFN)-gamma was significantly elevated in actively regressing BCCs compared with non-regressing BCCs. Furthermore, interleukin (IL)-2, tumour necrosis factor (TNF)-beta and CD3 delta tended to be elevated in actively regressing tumours, although not to statistically significant levels. IFN-gamma, IL-2, IL-10, TNF-beta, granulocyte-macrophage colony-stimulating factor and Fas ligand showed strong positive correlations with CD3 delta, indicating an association between infiltrating T cells and these cytokines. CONCLUSIONS: These findings support a role for T-helper 1 type cytokines in mediating spontaneous regression of BCCs.

CD3 Complex↗
PubMed2000

Topical retinoic acid enhances, and a dark tan protects, from subedemal solar-simulated photocarcinogenesis.

Studies into the effects of topical retinoic acid on photocarcinogenesis have yielded ambiguous findings. This may be due to different Experimental protocols and ultraviolet spectra. Retinoic acid is commonly used for a range of dermatologic conditions, and therefore it is important to resolve whether it affects skin tumor formation. To address this issue we used a protocol to mimic as closely as possible human use of retinoic acid. Two mouse strains were used: Skh:HR-1 (albino) and Skh:HR-2 (lightly pigmented). The pigmented mice more closely resemble Caucasian skin as they develop a light tan in response to ultraviolet radiation. This tan is greatly augmented by retinoic acid. As these are congenic mice, any differences can be attributed to the development of a tan. Mice were exposed to solar-simulated ultraviolet radiation, followed by treatment with 0.05% retinoic acid. This modeled exposure to sunlight during the day followed by retinoic acid treatment and a night-time period in the absence of sunlight. As it is recommended that ultraviolet exposure is minimized when using topical retinoic acid, the mice were only exposed to one-third of minimal edemal dose of ultraviolet radiation per day. This retinoic acid protocol augmented photocarcinogenesis. Retinoic acid decreased the latency period, reduced the probability that a mouse would survive without a tumor, and increased the number of tumors per mouse. All tumors induced were squamous cell carcinomas, and the skin between the tumors on mice treated with retinoic acid was found to contain carcinoma in situ upon histologic diagnosis. The light tan of the solvent-treated pigmented mice did not provide any protection, whereas the dark tan, which developed in Skh:HR-2 mice in response to retinoic acid, reduced photocarcinogenesis but did not overcome the augmenting effect of retinoic acid. Thus, using this experimental design, topical retinoic acid augmented photocarcinogenesis, and the ability to develop a dark but not light tan provided some, but limited, protection.

Administration, Topical↗
PubMed1999

Keratoacanthomas have an immunosuppressive cytokine environment of increased IL-10 and decreased GM-CSF compared to squamous cell carcinomas.

To investigate the relationship between keratoacanthoma (KA) and squamous cell carcinoma (SCC), cytokine mRNA in 12 KA and eight SCC were compared. Normal skin was also studied. Reverse transcription polymerase chain reaction (RT-PCR) was used to quantitate mRNA in each sample utilizing DNA standards. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as an internal control, and CD3delta as an indication of the T-cell infiltrate. KAs showed a significant increase in interleukin (IL)-10, and a decrease in granulocyte macrophage colony-stimulating factor (GM-CSF) mRNA compared to SCCs. CD3delta mRNA was also increased in the KAs. There was no difference between KAs and SCCs in expression of lymphotoxin-alpha, IL-2, interferon-gamma (IFN-gamma), IL-13, transforming growth factor-beta (TGF-beta), or the pro-inflammatory cytokines IL-8 or tumour necrosis factor-alpha (TNF-alpha). These results indicate that KAs spontaneously resolve in an immunosuppressive environment. KAs grow rapidly over a period of weeks and then involute. It is possible that a suppressed immune response enables unimpeded growth and that the KA cells rapidly undergo the finite number of cell divisions of which they are capable, and then die without reaching immortality.

CD3 Complex↗
PubMed1999

Topical treatment of interdigital tinea pedis: terbinafine compared with clotrimazole.

A multicentre, prospective, randomized, double-blind, parallel group study was undertaken to compare the efficacy and tolerability of topical terbinafine with topical clotrimazole in the treatment of interdigital tinea pedis. Patients were randomized to receive either terbinafine 1% cream twice daily for 1 week, followed by a similar placebo cream for 5 weeks, or clotrimazole 1% cream twice daily for 4 weeks. Outcome measures were: (i) mycological cure (negative culture); (ii) effective treatment (negative culture plus a symptom score of 2 or less out of a maximum score of 18); and (iii) complete cure (negative culture and a symptom score of 0); measured at 1, 4, 8 and 12 weeks after the commencement of the study. One hundred and four of the 217 patients randomized had a culture-confirmed dermatophyte infection at baseline. In these patients, 84.6% in the terbinafine group were culture negative after 1 week, compared with only 55.8% in the clotrimazole group. Both agents were well tolerated. The study showed that terbinafine achieves mycological cure more rapidly than clotrimazole. This may result in improved compliance and better control over transmission of infection.

Administration, Cutaneous↗
PubMed1999

Low-dose UVA and UVB have different time courses for suppression of contact hypersensitivity to a recall antigen in humans.

This study investigates the relative effects of low-dose solar-simulated ultraviolet, ultraviolet A, and ultraviolet B radiation on the elicitation of contact hypersensitivity to nickel in nickel-allergic volunteers. A xenon arc lamp with changeable filters was used to irradiate groups of volunteers daily, on separate areas of their lower backs, with both solar-simulated ultraviolet (ultraviolet B, ultraviolet AII + ultraviolet AI) and ultraviolet A (same ultraviolet AII content but twice the ultraviolet AI as the solar-simulated ultraviolet spectrum) for 1 and 2 d; 3, 4, and 5 d; and from 1 to 4 wk. A fourth group was irradiated for 1-5 d with the ultraviolet B component of solar-simulated ultraviolet. Following the final irradiation in each group, nickel-containing patches were applied to both ultraviolet-treated sites and adjacent, unirradiated control sites. Erythema caused by nickel contact hypersensitivity at each site was quantitated 72 h later with a reflectance erythema meter. By comparing the nickel reactions of irradiated and unirradiated skin, ultraviolet immunosuppression was assessed with the different spectra and durations of ultraviolet exposure. We found significant immunosuppression with daily doses of ultraviolet B and ultraviolet A equivalent to approximately 6 min of summer sun exposure, and that ultraviolet A and ultraviolet B exerted their maximal immunosuppressive effects at different times. Solar-simulated ultraviolet-induced immunosuppression was significant after one exposure, near-maximal after two exposures and remained elevated thereafter. Ultraviolet B-induced immunosuppression was lower than that induced by solar-simulated ultraviolet, but followed a similar time-course. In contrast, ultraviolet A-induced immunosuppression was transient, peaking after three exposures. Immune responses returned towards normal with subsequent ultraviolet A exposure, suggesting that an adaptive mechanism may prevent immunosuppression by continued ultraviolet A irradiation.

Adolescent↗
PubMed1999

Regression of melanoma, but not keratoacanthoma, is associated with increased HLA-B22 and decreased HLA-B27 and HLA-DR1.

Sixty three Caucasian patients with either melanoma, keratoacanthoma or squamous cell carcinoma were human leucocyte antigen (HLA) typed. The regressing tumour groups were compared with their non-regressing counterparts, and the patient groups were compared with a control Caucasian population. Melanoma patients showing histological regression were more likely to be HLA-B22 positive, and HLA-B27 and -DR1 negative, than those without features of regression. When compared with a control population, the group of melanoma patients were more likely to be HLA-B22 positive. Comparison of the group of keratoacanthomas, a self-regressing tumour, and the group of squamous cell carcinomas, a non-regressing tumour, did not show any significant differences in HLA typing.

Carcinoma, Squamous Cell↗
PubMed1999

Measurement of in vivo sunscreen immune protection factors in humans.

This study investigates the level of protection provided by sunscreens against solar-simulated UV radiation-induced immunosuppression in humans. The in vivo immune protection factors (IPF) of two broad-spectrum sunscreens were determined by assessing their ability to prevent UV-induced suppression of nickel contact hypersensitivity (CHS) in 15 nickel-allergic volunteers. Each volunteer was irradiated on unprotected skin of the back with different doses of UV daily for 4 days. Multiples of these UV doses were concurrently delivered to sunscreen-treated sites on the contralateral back. Nickel patches were then applied to both irradiated sites and adjacent, unirradiated control sites. Nickel-induced erythema at each site was measured 72 h later with a reflectance spectrometer. Comparison of the nickel reactions of irradiated and unirradiated skin revealed linear UV dose-responses for immunosuppression in both unprotected and sunscreen-treated skin. The minimum level of immunosuppression that can be reliably detected with this method is 20%. Therefore, the UV dose that reduces mean nickel CHS by 20% is the minimal immune suppression dose (MISD). Sunscreen IPF were determined by dividing the mean MISD of sunscreen-treated skin by that of unprotected skin. The sunscreens, with sun protection factors of 9 and 24, had IPF of 6.5 and > 25, respectively.

Adult↗
PubMed1998

UVA-induced immunosuppression.

It has previously been demonstrated that chronic low-dose solar-simulated ultraviolet (UV) radiation can induce both local and systemic immunosuppression as well as tolerance to a topically applied hapten. Epidermal cells from UV-irradiated mice inhibit spontaneous regression of tumours indicating that UV-induced immunosuppression is likely to permit the outgrowth of developing UV-induced skin tumours. We have used a chronic low-dose UV-irradiation protocol to investigate the effects of UVA on the skin immune system of C3H/HeJ mice. Irradiation with UVA + B significantly suppressed the local and systemic primary contact sensitivity (CS) response to the hapten TNCB. Furthermore UVA + B reduced Langerhans cell (LC) and dendritic epidermal T cell (DETC) numbers in chronically UV-irradiated mice. UVA-irradiation induced local, but not systemic, immunosuppression and reduced LC (32%) but not DETC from the epidermis compared to the shaved control animals. Treatment of mice with UVA + B or UVA radiation also induced an impaired secondary CS response, and this tolerance was transferable with spleen cells. Therefore exposure of C3H/HeJ mice 5 days per week for 4 weeks with UVA can induce local immunosuppression and tolerance. One of the mechanisms by which UVA affects biological systems is production of reactive oxygen species. We have also shown that Vitamin E, an inhibitor of lipid peroxidation, prevents UV-induced immunosuppression and loss of LC. It is possible that the UVA in UV radiation induces epidermal lipid peroxidation which stimulates LC migration from the epidermis, thus contributing to UV-induced immunosuppression. Hence, inhibition of epidermal lipid peroxidation by Vitamin E may provide some protection to the skin immune system from these effects of UV.

Animals↗
PubMed1998

Bioactive tumour necrosis factor alpha but not granulocyte-macrophage colony-stimulating factor correlates inversely with Langerhans's cell numbers in skin tumours.

Langerhans' cells (LCs) are thought to play an important role in presentation of tumour antigens for the induction of anti-tumour immunity. Epidermis overlying some transplanted murine skin tumours contains increased numbers of LCs; however, alterations in LC numbers are not related to tumour antigenicity or host immunity, suggesting that another factor(s), such as tumour-produced cytokines, influences LC density. It has been postulated that dendritic epidermal T cells (DETCs) play a role in immunosurveillance within the normal epidermis. Two cytokines which potentially alter LC numbers or function include granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumour necrosis factor-alpha (TNF-alpha). GM-CSF maintains LC viability in culture, and there are reports that it can increase LC density. There is evidence that TNF-alpha induces LC to migrate from the epidermis. In the present study, LC densities in regressor and non-regressor murine skin tumours and overlying epidermis were enumerated, and bioactive GM-CSF and TNF-alpha present in the tumours were measured. We found significantly increased epidermal LC numbers above non-regressor, but not regressor, tumours. DETC numbers were significantly increased above some tumours. Although all tumour types produced TNF-alpha, the regressors, which did not increase LC numbers, produced the most TNF-alpha. In contrast, tumour production of GM-CSF did not correlate with any pattern of alteration of LC density or tumour growth. Tumour production of neither cytokine nor tumour growth correlated with DETC numbers overlying tumours. Our results suggest that TNF-alpha may be associated with skin tumour regression and may prevent LC accumulation by tumours.

Animals↗
PubMed1998

Comparison of one week of oral terbinafine (250 mg/day) with four weeks of treatment with clotrimazole 1% cream in interdigital tinea pedis.

Treatment of interdigital tinea pedis often involves long-term therapy with topically applied preparations. Effective oral preparations, such as the allylamine terbinafine (Lamisil), taken over a shorter period, could provide a useful therapeutic alternative. A total of 269 patients from five centres with clinically diagnosed interdigital tinea pedis were entered into this double-blind, randomized, double-dummy, parallel-group study comparing oral terbinafine 250 mg once daily for 1 week with 1% clotrimazole (Canesten) cream applied twice daily for 4 weeks. Of these, 137 patients were evaluable for efficacy (confirmed dermatophyte infection by microscopy and culture): 63 terbinafine and 74 clotrimazole. At week 4, the mycological cure rates (negative culture at week 1 and negative results on microscopy and culture at week 4 onwards) were very similar (71% for clotrimazole and 72% for terbinafine). There was a faster response rate in the terbinafine group with respect to signs and symptoms at week 1. Both treatments were equally well tolerated; adverse events occurred equally in the two groups. In conclusion, oral terbinafine in a single daily dose of 250 mg for 1 week is as effective and as well tolerated as 1% clotrimazole cream applied twice daily for 4 weeks in the treatment of interdigital tinea pedis.

Adolescent↗
PubMed1998

Ultraviolet radiation induced suppression of Mantoux reactions in humans.

The effects of low dose ultraviolet (UV) radiation on delayed type hypersensitivity responses to tuberculin purified protein derivative were investigated in 17 healthy, Mantoux-positive volunteers. Suberythemal and erythemal doses of solar simulated UV from a fluorescent lamp source were delivered to the subjects' lower backs daily for five consecutive days. Mantoux testing with intradermally injected purified protein derivative was then performed at both the irradiated sites and an adjacent, unirradiated site, and the Mantoux induced erythema was quantitated 72 h later with a reflectance erythema meter. In comparison with the unirradiated Mantoux sites, Mantoux induced erythema was significantly reduced at the irradiated test sites. In six subjects, we compared the effects of chronic versus short term UV irradiation on the Mantoux reaction. These volunteers were irradiated on one side of their lower backs with the 5 d UV protocol, and on the other side of their backs for 4 or 5 wk. In all but one subject, the short irradiation protocol induced greater suppression of Mantoux responses than prolonged UV exposure. We conclude that even suberythemal doses of UV significantly reduce delayed type hypersensitivity responses to purified protein derivative, and that an adaptive mechanism appears to counteract the immunosuppressive effects of chronic irradiation.

Adult↗
PubMed1998

Sunscreens and vitamin E provide some protection to the skin immune system from solar-simulated UV radiation.

Previous studies have indicated that sunscreens designed to protect from erythema do not adequately prevent immunosuppression. Mice were irradiated with suberythemal doses of solar-simulated ultraviolet radiation (ssUVR) to assess the immunoprotective ability of sunscreens. Whereas C3H/HeJ and BALB/c mice had similar sensitivities to ssUVR-induced inflammation, C3H/HeJ mice were more sensitive to ssUVR-induced immunosuppression. Octyl dimethyl-p-aminobenzoic acid did not protect from immunosuppression and, thus, had an immune protection factor (IPF) of 1. 2-Ethylhexyl-p-methoxycinnamate and microfine titanium dioxide provided limited protection, both having IPF values of 1.127. Immune protection by the sunscreens appeared to be dependent upon absorption of UVA as well as UVB, and was much less than predicted from the sun protection factor. Vitamin E, an inhibitor of lipid peroxidation, also protected the immune system, with an IPF of 1.2, indicating that oxidation of lipids is involved in UVR-induced immunosuppression, and that it should be possible to develop sunscreens which protect the immune system.

Animals↗
PubMed1997

Dendritic epidermal T-cell involvement in induction of CD8+ T cell-mediated immunity against an ultraviolet radiation-induced skin tumor.

Murine epidermis contains 2 distinct cell populations which contribute to the skin immune system, Langerhans cells (LC), and dendritic epidermal T cells (DETC). LCs are important in the induction of immunity against a wide range of antigens; however, the function of DETC is unclear. To investigate the roles of these epidermal cells (EC) in protective antitumor immunity, an in vivo model of an ultraviolet radiation-induced fibrosarcoma, UV-13-1, was used. Mice were immunized with tumor antigen-pulsed EC followed 10 days later by an injection into the ear of 10(5) tumor cells, which did not lead to formation of a detectable tumor, but was intended to simulate the influence of a developing tumor on the ensuing immune response. The mice were then challenged with 2 x 10(6) viable tumor cells in each flank, sufficient to result in growth of a measurable tumor. Protective immunity was induced by DETC, and shown to be long-lasting, with tumors inoculated 160 days after immunization being effectively rejected. The effector cells responsible for protective immunity were CD8+ T cells. Delayed-type hypersensitivity generated by tumor antigen-pulsed EC was dependent on LCs, with no involvement of DETCs. This response, in contrast to that of DETC, required prior culture of EC with GM-CSF, but failed to inhibit tumor growth or incidence. Thus DETC and LC can both activate antitumor immune responses, although only the DETC-dependent response results in protective immunity in the presence of a developing tumor.

Animals↗
PubMed1997

T helper 1 cytokine mRNA is increased in spontaneously regressing primary melanomas.

Spontaneous tumor regression, which is observed clinically and histologically in some primary melanomas, occurs in the absence of any effective therapy. It is probably immunologically mediated, because regressing melanomas are infiltrated with larger numbers of activated T cells, primarily CD4+, than nonregressing melanomas. To investigate the hypothesis that spontaneous regression of melanomas is caused by T-cell cytokine production, cytokine mRNA expression in 20 primary melanomas was examined using a noncompetitive, quantitative reverse-transcriptase polymerase chain reaction method. DNA standards were used to generate known numbers of molecules in each sample. Results were standardized to the internal control, glyceraldehyde-3-phosphate dehydrogenase. mRNA for CD35, lymphotoxin (TNF-beta), and IL-2 were significantly elevated in the ten regressing melanomas compared to the ten nonregressing melanomas. IFN-gamma mRNA was also elevated in regressing melanomas but failed to reach statistical significance. The Th2 cytokines IL-10 and IL-13 did not show differences in the regressing melanomas compared to nonregressing melanomas; neither did the pro-inflammatory cytokines IL-1alpha, IL-1beta, IL-6, IL-8, and TNF-alpha, nor the growth factors, bFGF and TGF-beta or GM-CSF. This study shows an association between Th1 cytokines and spontaneously regressing melanomas. Although we have not shown that these cytokines cause regression, these findings support our hypothesis that activated CD4+ T cells may mediate melanoma regression by secretion of Th1 cytokines.

Adult↗
PubMed1997

Broad-spectrum sunscreens provide greater protection against ultraviolet-radiation-induced suppression of contact hypersensitivity to a recall antigen in humans.

This study investigates the extent to which sunscreens protect humans from ultraviolet (UV)-radiation-induced immunosuppression. In the presence of solar-simulated UV, three sunscreens with differing UVA transmission were assessed for their ability to protect the contact hypersensitivity (CHS) response to nickel of 16 nickel-allergic subjects. The sunscreens contained 2-ethylhexyl para-methoxycinnamate (cinnamate), cinnamate with oxybenzone, or cinnamate with zinc oxide, respectively. All had sun protection factors of 10 and hence inhibited UV erythema to similar extents. Volunteers were irradiated on their backs with suberythemal UV daily for 5 d after application of the sunscreens and their base lotion to different sites. Nickel-containing patches were then applied to both UV-treated sites and adjacent, unirradiated control sites. Erythema caused by nickel CHS at each site was quantitated 72 h later with a reflectance erythema meter. In comparison of the nickel reactions of irradiated and unirradiated skin, there was 35% mean immunosuppression in unprotected UV-treated skin. Significant immunosuppression also occurred at sites irradiated through the narrow-spectrum cinnamate-only sunscreen but was prevented by the two broad-spectrum sunscreens. To determine whether UV-induced suppression of the nickel response is specific for cell-mediated immunity or reflects suppression of nonspecific inflammation, a further 16 subjects were patch-tested with a skin irritant, sodium lauryl sulfate (SLS), following a sunscreen and irradiation protocol identical to that of the nickel volunteers. UV had no significant effect on SLS responses. We conclude that nickel patch testing is a valid means of assessing UV-induced immunosuppression in humans and that even with suberythemal UV, immune protection was provided only by sunscreens filtering both UVA and UVB.

Dermatitis, Allergic Contact↗