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N J Neumann

Publications and source records attributed to N J Neumann.

9 recordsLinked to original sources
PubMed1997

Evaluation of PUVA bath phototoxicity.

Administration of 8-methoxypsoralen in a dilute bath water solution is an effective therapeutic alternative to its systemic application, avoiding systemic side effects. Although PUVA bath photochemotherapy is now widely used, standardized guidelines are not yet available. Therefore, the aim of our study was to determine the optimal time interval between 8-methoxypsoralen bath and UVA irradiation and the persistence of photosensitivity after PUVA bath treatment. In volunteers the highest photosensitivity was observed following UVA irradiation immediately after PUVA bath. A sharp increase of the minimal phototoxic dose could be demonstrated after only 1 h, indicating a rapid loss of 8-methoxypsoralen activity. Irradiation 2 h after 8-methoxypsoralen bath failed to induce any PUVA erythema. This indicates that the optimal time for UVA irradiation is immediately after the 8-methoxypsoralen bath. In contrast to systemic PUVA therapy, 2 h after PUVA bath therapy, the remaining phototoxicity is minimal, so that no stringent restrictions of the patient's behaviour are needed.

Adult↗
PubMed1997

Photo hen's egg test: a model for phototoxicity.

The aim of this investigation was to establish a new model for phototoxicity which is more advanced than the widely used cultures of yeasts, bacteria or cells of various origin, and at the same time to avoid animal testing. We studied the extraembryonal vasculature of the incubated hen's egg. This model was originally introduced by toxicologists as an alternative to the rabbit's eye irritation test (Draize test). In the photo hen's egg test, substances are applied to the embryo's yolk-sac blood vessel system at a non-toxic concentration and are irradiated with 5 J/cm2 ultraviolet A (UVA) (320-400 nm). Promethazine, haematoporphyrin, ciprofloxacin and 8-methoxypsoralen were tested in this system. Death of the embryo, membrane discoloration and haemorrhage are parameters for phototoxic damage, which were recorded during an observation period of 24 h. These well-known phototoxic substances induced pronounced damage of the yolk-sac membrane and blood vessels which was not found in the controls (test substance alone, UVA alone or untreated) using a 2 x 2 factorial test design. The photo hen's egg test serves as a valid screening model for substances supposed to be photosensitizers owing to a phototoxic mechanism.

Animals↗
PubMed1996

The history of photography in dermatology. Milestones from the roots to the 20th century.

From the Middle Ages to the 20th century, talented artists have created illustrations of signs of human diseases. Since the birth of photography in 1840, artists and physicians have used photographic techniques to illustrate the diseases of the skin; dermatology especially relies on these visual signs. In dermatology today, photography is still very important because of the need for adequate illustrations in medical textbooks and journals. From the early days of daguerreotypes to modern times, medical photography was developed in different stages and many physicians have taken part in the development of photographic techniques and chemistry. This historical survey describes the milestones in the development of medical photographic illustration from its beginning to the 20th century.

Dermatology↗
PubMed1994

Pattern analysis of photopatch test reactions.

In a multicenter study, photopatch test results from more than 1500 patients were evaluated between 1985 and 1990 and from 614 patients between 1990 and 1992. Photopatch testing was conducted according to a standardized procedure. Nearly half of the photoreactions were unclassifiable according to the classic definitions of photoallergic or phototoxic reactions. To facilitate the interpretation of these remaining photopatch test reactions, we developed a computerized substance specific reaction pattern analysis. By sequential readings from immediately after irradiation up to 72 h later and by morphological qualification of the reactions, the time course and morphological changes of each individual reaction were monitored. The summation of each individual photoreaction resulted in an overall reaction pattern of a specific substance. Four main categories could be distinguished. The first category was characterized by a peak immediately after irradiation followed by a descrescendo reaction. The second category comprized reactions combining an immediate with a delayed reaction. The third category exhibited a plateau-like delayed reaction. The fourth category showed delayed reactions in a crescendo pattern. Whereas category 1 represents classic phototoxic and category 4 classic photoallergic reaction patterns, the underlying mechanisms of categories 2 and 3 remain to be investigated. Typical substances of category 1 were many of the tested systemic drugs, such as furosemide, most of which are well-known phototoxic agents. Disinfectants, nonsteroidal anti-inflammatory agents and phenothiazines showed the reaction patterns of categories 2 and 3. A delayed type reaction (category 4) could be demonstrated for well-known photoallergens such as fenticlor, musk ambrette, and ultraviolet adsorbents in sunscreens.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗