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Biomedical subjects

R Marks

Publications and source records attributed to R Marks.

At least 163 records · Page 9Linked to original sources
PubMed1996

The sea to air bacteria transfer from the coastal waters.

Bacteria transfer from the water into the air may play an important role in bioaerosol cycle. Bubbles raising through the water column collect bacteria but also other suspended material and transport them towards water surface. When the bubble burst at the water surface collected material are skimmed off the bubble to become highly enriched in jet and film drops. After ejection airborne droplets can evaporate and as small droplets can be transported even to remote locations. Such a stream of aerosol droplets may carry stream of bacteria scavenged from the water column. The fate of bacteria in the air may possibly depend on the environmental conditions like intensity of sunlight or ambient air humidity. In addition the wind speed might be responsible for both wave/bubble mediated production of marine originated droplets and their transport in the atmosphere. The evidences that bacteria are transferred from the breaking waves, in particular in the coastal zone, were observed during several field experiments conducted in 1994 and 1995 over the Gulf of Gdansk and the Baltic Sea coast. Enhanced sea to air bacteria transfer were noticed over the polluted waters where in addition gas supersaturations in the water were recorded. Further laboratory investigations of bacteria scavenge via bubbles produced by single capillary and by plume of bubbles produced by ceramic stone indicated high enrichment within both mesophile and psychrophile bacteria categories.

Aerosols↗
PubMed1995

Peripheral deletion of antigen-reactive T cells in oral tolerance.

Oral administration of antigen is used to induce antigen-specific peripheral immune tolerance. As well as preventing systemic immune responses to ingested proteins, oral tolerance to autoantigens has also been used to suppress autoimmune diseases in animals and humans. Both active suppression and clonal anergy are suggested to be mechanisms of oral tolerance, depending on the dose of antigen fed. Here we report that oral antigen can delete antigen-reactive T cells in Peyer's patches, in mice transgenic for the ovalbumin-specific T-cell receptor genes. The deletion was mediated by apoptosis, and was dependent on dosage and frequency of feeding. At lower doses deletion was not observed; instead there was induction of antigen-specific cells that produced transforming growth factor (TGF)-beta and interleukin (IL)-4 and IL-10 cytokines. At higher doses, both Th1 and Th2 cells were deleted following their initial activation, whereas cells which secrete TGF-beta were resistant to deletion. These findings demonstrate that orally administered antigen can induce tolerance not only by active suppression and clonal anergy but by extrathymic deletion of antigen-reactive Th1 and Th2 cells.

Administration, Oral↗
PubMed1995

An overview of skin cancers. Incidence and causation.

The incidence and mortality rates of skin cancer are rising in the United States and in many other countries. Concerns about stratospheric ozone depletion adding to the problem have made many organizations look at public and professional health programs as a possible solution. Early detection can reduce the problem in the short term, because mortality due to melanoma is clearly related to the depth of invasion of the tumor when it is removed. This is the factor which is amenable to change in an education program on early detection. Exposure to sunlight is clearly related to risk of development of skin cancer, including both melanoma and nonmelanoma skin cancers. This is the component of the equation of constitutional predisposition plus exposure to environmental risk factors leading to skin cancer that is amenable to change as a result of educational programs. On the basis of available data, there is a case for further development, provision, and evaluation of public and professional education programs designed to control what is becoming a major public health problem in the community.

Australia↗
PubMed1995

Increased risk of skin cancer: another Celtic myth? A review of Celtic ancestry and other risk factors for malignant melanoma and nonmelanoma skin cancer.

It is often stated that persons of Celtic origin have an increased risk of skin cancer, but the evidence for this is almost exclusively anecdotal. We believe that the possibility of the Celts being at greater risk of skin cancer has important implications with regard to management in particular and in assisting our understanding of carcinogenesis in general. For these reasons we have reviewed all those studies implicating Celtic ancestry in the development of both malignant melanoma and nonmelanoma skin cancer.

Ethnicity↗
PubMed1995

The epidemiology of non-melanoma skin cancer: who, why and what can we do about it.

Non-melanoma skin cancer (NMSC) comprised of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the most common cancers in humans in many countries. Sunlight plays a major part in the development of these tumours which appear predominantly on areas of the most frequently exposed skin. The site distribution for BCC and SCC is not the same, with SCC being most common on the sites of very heavy exposure and BCC becoming more common on areas of only moderate exposure, e.g. upper trunk in men and women and lower leg in women. Incidence rates of NMSC, where they are being recorded, show rises over time. Mortality rates, on the other hand, have been dropping most of this century until they have been levelling out recently. The case fatality rate due to SCC appears to be between 1-2%. The malignant transformation rate of actinic keratoses to SCC appears to be very low. Studies on similar populations at different latitudes allow estimates to be made of increases which might occur with increasing exposure to ultraviolet radiation (UVR) over a life time. These have been used to estimate the possible increases in NMSC due to stratospheric ozone depletion. Finally, recent studies on the reduction of existing actinic keratoses and prevention of new ones with regular use of sunscreen augurs well for prevention of NMSC in the future.

Basal Cell Carcinoma↗
PubMed1995

Fluticasone propionate 0.05% cream in the treatment of atopic eczema: a multicentre study comparing once-daily treatment and once-daily vehicle cream application versus twice-daily treatment.

The aim of this study was to compare the efficacy and safety of once-daily with twice-daily application of a 0.05% cream formulation of fluticasone propionate in the treatment of atopic eczema in adults and children. Two hundred and seventy patients with moderate to severe atopic eczema were enrolled in the study, and randomized to receive either once-daily or twice-daily fluticasone propionate 0.05% cream for 4 weeks. Patients randomized to the once-daily group also received the vehicle cream to ensure that the study remained blinded. The clinical response of a preselected target area of affected skin was assessed by investigators at weekly intervals and compared with the baseline. Analysis of the investigators' overall assessment of the response of the target area for both the 'intent-to-treat' population and the per protocol population showed that 79-85% of patients were judged a clinical success. For both populations, there was no statistically significant difference between the response to once-daily and twice-daily active treatment (intent-to-treat; P = 0.35; 95% confidence interval for difference -14.2 to +5.0 percentage points: per protocol; P = 0.42; 95% confidence interval for difference -14.7 to +6.2 percentage points.) The improvement in the signs and symptoms was judged a success in 95-97% of patients. There was an equal reduction in severity scores for disease activity in both groups, and the speed of symptom relief was similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1995

Protracted cutaneous disorders in association with low CD4+ lymphocyte counts.

We report two patients with skin disorders usually associated with severe immunosuppression, who had low CD4+ lymphocyte counts but normal immunoglobulin levels. The patients were HIV negative, and had CD4+ lymphocyte counts just above 300/mm3, but they presented with cutaneous manifestations of profound immunodeficiency. Idiopathic CD4+ lymphocyte deficiency is a recently described syndrome which may present with dermatological disease. We discuss the symptom complex of our patients in relationship to the diagnosis of idiopathic CD4+ lymphocyte deficiency.

Adult↗
PubMed1995

The growth of ichthyotic epidermal cells in a 3-dimensional reconstruction of human skin, the skin equivalent.

We have studied the differentiation of ichthyotic epidermis in vitro using the skin equivalent model. The morphology of these ichthyotic cultures has been investigated using histopathological and histometric techniques including epidermal and stratum corneum thickness measurements. The skin equivalents have also been investigated for the presence of markers of differentiation using immunolocalization techniques. These markers include the 65.5 and 67 kDa keratins, desmoplakin, involucrin, laminin and filaggrin. It has been shown that the ichthyotic epidermis develops a fully differentiated epidermis and stratum corneum, equivalent to those seen in normal skin equivalents.

Cell Differentiation↗
PubMed1995

Cancer of the skin in the next century.

One can confidently predict that the 21st century will be a span of intense activity in unraveling the precise molecular and biochemical events that lead to the various forms of cutaneous cancers. These discoveries will lead to new approaches in our therapeutic armamentarium that currently do not exist. Eventually, the incidence rates and mortality rates from cancers of the skin will markedly decline--the finite goal of all the combined endeavors of the scientific and practicing medical community.

Developing Countries↗
PubMed1995

The effects of protective occlusive gloves on stratum corneum barrier properties.

Data suggests that protection from gloves is paradoxically reduced because of effects of occlusion on the skin. The aim of this study was to characterize these effects on physical and functional properties of stratum corneum. Volunteer trials were conducted using patches of polyvinyl chloride (PVC) glove material on the skin. Impairment of barrier function was assessed by measuring transepidermal water loss (TEWL). Hydration and water sorption-desorption was assessed using skin conductance. The major finding was a short-term impairment of barrier function, measured as an increase in TEWL of 1.7 gn-2h-1 (95% C.I. 0.4 to 2.6 gn-2h-1,p < 0.01). Temporary increases in hydration and water sorption were also observed. On this basis, the effects of wearing PVC gloves over 2 days on stratum corneum barrier properties on the dorsum of the hand were studied. TEWL measurements remained elevated by 1.5 gn-2h-1 the day after occlusive glove removal (95% C.I. 0.2 to 2.8 gn-2h-1, p < 0.01), indicating a possible cumulative effect. In conclusion, our studies demonstrate a potential hazard resulting from the repeated use of protective gloves.

Adult↗
PubMed1995

A stepwise procedure for evaluating irritant materials in normal volunteer subjects.

1. The cutaneous response to a known irritant has been assessed in human volunteer subjects using both clinical scoring and two non-invasive instrumental methods; erythema measurement using an erythema meter and capillary blood flow using a laser Doppler device. 2. Aqueous solutions (0.5% and 1%) of sodium hydroxide were applied to back skin for 3, 15 and 60 min with assessments immediately after removal and at 1, 24 and 48 hours. 3. Increased erythema was seen with increasing duration of exposure and an increase was also seen at 1 h, 24 h and 48 h after removal of the patch. The results obtained with the erythema meter paralleled the clinical erythema scores. However, the laser Doppler device showed the greatest changes immediately after removal of the patch with subsequent readings showing a gradual decrease. 4. Statistical analysis of the data has been carried out to determine the accuracy and precision of the assessment procedures and to determine the minimum test panel size for detecting irritant reactions. 5. Comparison between back and forearm skin indicated a greater sensitivity to sodium hydroxide on the back. 6. The results of this study define an ethical approach to testing irritant materials in human subjects and provide the basis for the development of a classification system for cutaneous irritants.

Adolescent↗
PubMed1995

Skin cancer. Recognition and treatment.

There is a worldwide increasing incidence of all forms of skin cancer among Whites as a result of increased sun exposure. Basal cell and squamous cell carcinomas, the most common tumours of the head and neck, are relatively benign neoplasms of elderly individuals. Malignant melanoma, however, has the potential for early metastasis and may occur in early adult life. The increase in malignant melanoma is particularly disturbing, and is a clear indication for skin screening clinics. Although surgical excision is the primary treatment of choice for skin tumours, various drugs may be of therapeutic value. Fluorouracil cream is a useful treatment for solar keratoses. Retinoids are particularly suitable for patients with large numbers of nonmelanoma skin cancer lesions and solar keratoses. For malignant melanoma, arterial limb perfusion with high concentrations of cytotoxic drugs may be performed both as an adjunctive and therapeutic manoeuvre. Treatment of metastatic melanoma with cytotoxic agents is associated with low response rates and high toxicity. However, trials with combined interferon-alpha, interleukin-2 and cytostatic drugs have produced promising preliminary results.

Bowen's Disease↗