Molecular defects of uroporphyrinogen decarboxylase in a patient with mild hepatoerythropoietic porphyria.

The molecular defect of uroporphyrinogen decarboxylase (UROD) was examined in a patient with mild hepatoerythropoietic porphyria. To elucidate the UROD defect, we cloned UROD cDNAs from EBV-transformed lymphoblastoid cells of the proband using reverse transcriptase-polymerase chain reaction. Nucleotide sequence analysis of the cloned UROD cDNAs revealed two separate missense mutations, each occurring in a separate allele. One mutation was a Val134-->Gln transition, and was due to three sequential point mutations (T417G418T419-->CCA); the other mutation was a His220-->Pro transition (A677-->C). UROD phenotype studies demonstrated that the TGT-->CCA mutation was inherited from the father, and the A-->C mutation was inherited from the mother. In contrast to the null activity previously described for a mutant UROD from a patient with familial porphyria cutanea tarda, these mutant URODs had subnormal but substantial enzyme activities, when expressed in Chinese hamster ovary cells. This is the first demonstration of a mutation caused by three sequential base substitutions.

Erythrocyte uroporphyrinogen decarboxylase activity in porphyria cutanea tarda: a study of 40 consecutive patients.

We measured uroporphyrinogen decarboxylase (UROD) activity in erythrocyte lysates obtained from 40 consecutive patients with porphyria cutanea tarda (PCT) without selection for family history. Enzyme determinations indicated that 28% of the patients had abnormally decreased UROD activity in erythrocytes; this finding did not always correlate with family history. Two siblings with PCT and normal erythrocytic, but abnormally decreased hepatic UROD activities, were encountered. This finding suggests that familial PCT may occur not only with decreased erythrocyte UROD activity, but also with a normal UROD activity in erythrocytes.

An animal model for evaluation of topical photoprotection against ultraviolet A (320-380 nm) radiation.

Recent studies reporting UVA (ultraviolet A radiation 320-380 nm) as an integral part of the cumulative sun-induced damage in human skin have prompted an interest in developing effective UVA photoprotective agents. The development of such compounds has been impeded by the absence of a clinically relevant animal model for evaluating their efficacy. This report describes the development and use of such a laboratory animal system. Selected concentrations of oxybenzone (2-hydroxy-4-methoxybenzophenone) in vehicle (0.1% to 6%) or vehicle alone were applied to the depilated dorsal skin of 30 Hartley strain female albino guinea pigs. The skin was irradiated with solar simulated UVA from a xenon light source. Acute radiation-induced damage was assayed by erythema grading and inhibition of [3H]thymidine incorporation into epidermal DNA. Data from erythema grading studies indicated that a significant degree of photoprotection was achieved with 6%, 3%, and 1% solutions of benzophenone compared with the control vehicle; the 6% solution was significantly more photoprotective than the 3% and 1% solutions. A 6% solution afforded significant photoprotection when assayed by [3H]thymidine incorporation.

Surfactant-induced alteration of arachidonic acid metabolism of mammalian cells in culture.

Primary irritancy in human and animal skin is characterized by an inflammatory reaction mediated, in part, by membrane-derived arachidonate metabolites. One of the mechanisms of this reaction was investigated in cultured mammalian cells using three surfactants: linear alkyl benzene sulfonate (LAS), alkyl ethoxylate sulfate (AEOS), and TWEEN 20. These compounds listed in order in vivo irritancy are LAS greater than AEOS greater than TWEEN 20. Each of these compounds was studied in C3H-10T1/2 cells and human keratinocytes which had been prelabeled with 3H-labeled arachidonic acid (AA). After labeling, media were removed, cells were washed, and fresh media with or without surfactant were added. Cells were then incubated for 2 hr, media were removed and centrifuged, and an aliquot was assayed by liquid scintillation for release of label. In C3H-10T1/2 cells LAS and AEOS in 5-50 microM concentration stimulated 2 to 10 times the release of [3H]AA as compared to controls. In contrast, concentrations of 50-100 microM of TWEEN were required to release [3H]AA. With keratinocytes the same rank order of surfactant concentrations necessary for release was obtained as found with C3H-10T1/2 cells. High-performance liquid chromatography of media extracts of both cell systems revealed surfactant stimulation of the production of cyclooxygenase AA metabolites. These results confirm the induction of release by primary irritants of fatty acid groups from membrane phospholipids. Subsequent metabolism of these fatty acid groups are an integral part of the primary irritant response. Data presented with three known irritants in this in vitro model show a direct correlation with in vivo studies.

Hepatoerythropoietic porphyria: clinical, biochemical, and enzymatic studies in a three-generation family lineage.

Hepatoerythropoietic porphyria is caused by a marked deficiency in the activity of uroporphyrinogen decarboxylase, an enzyme that is essential for heme biosynthesis. It has been hypothesized that uroporphyrinogen decarboxylase deficiency is inherited as a homozygous defect in the disease. This suggestion has been supported by reports of a deficiency of the enzyme in parents of patients with the disorder. Further confirmation would be provided by demonstrating a similar uroporphyrinogen decarboxylase deficiency in the offspring of such patients. This study follows the enzymatic defect throughout three generations of a family in which a second-generation male was shown to have hepatoerythropoietic porphyria. Detailed biochemical and enzymatic analyses revealed a moderate deficiency of uroporphyrinogen decarboxylase in both the proband's parents and in his three children, all of whom were asymptomatic. The mildness of the clinical symptoms in the proband correlated with a higher level of residual enzyme activity than that in previously described patients. We conclude that clinically manifested hepatoerythropoietic porphyria results from the homozygous inheritance of a defect in the uroporphyrinogen decarboxylase gene, that the severity of clinical symptoms is probably related to the level of residual enzyme activity, and that the genetic defect of uroporphyrinogen decarboxylase in hepatoerythropoietic porphyria can be heterogeneous.

The effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) on phospholipid metabolism of human epidermal keratinocytes in culture.

The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulated the release of [3H]choline from prelabelled membrane phospholipids of cultured keratinocytes obtained from normal human skin. In contrast, TPA in the concentration range of 10(-12) to 10(-6) g/ml failed to induce deacylation of [3H]arachidonic acid or stimulate [3H]prostaglandin production in prelabelled keratinocytes. In addition, TPA did not induce [3H]choline incorporation into the membrane phospholipids of these cells. The previously reported inability of TPA to stimulate a proliferative response in these cell cultures may be related to the resistance of these cells to TPA-induced alterations of arachidonate metabolism.

Photosensitivity. Classification.

Light is a heterogeneous moiety that is vital for the perception and maintenance of all life on earth. Specific advantages as well as adverse effects are associated with particular wavelengths of light. An etiologic classification of the adverse responses or "photosensitivity disease" is presented as an introduction to this issue.

Quinidine photosensitivity.

A 55-year-old woman developed a dermatitis confined to light-exposed areas while taking quinidine gluconate, warfarin sodium, furosemide, spironolactone, and digoxin after cardiac surgery. Phototesting indicated a normal erythematous response to 290- to 320-nm ultraviolet radiation, but she developed erythema from 6 joules/sq cm of 320- to 400-nm radiation (ultraviolet A [UV-A]), a much lower dose than needed to produce a reaction in normal individuals. Two days after she discontinued quinidine and warfarin, phototesting showed no reaction to as much as 20 joules/sq cm of UV-A. One week after resuming quinidine (but not warfarin), she again reacted to 8 joules/sq cm of UV-A. No reactivity was elicited when the preparation was applied to the skin or injected into the dermis either with or without subsequent UV-A irradiation.

Photosensitivity diseases related to interior lighting.

The most frequently used source of indoor lighting is the fluorescent tube. Although there are major variations in phosphors, the majority of these lamps are safe, efficient, and economical illuminators. These fluorescent light sources are currently our primary source of visible light; however, they emit small amounts of ultraviolet A light (UVA) as well as a somewhat larger percentage of infrared radiation. Photosensitivity diseases have been reported in each of these three broad wavelength bands. Specific examples include heat urticaria from infrared exposure, contact photosensitivity of the phototoxic type following exposure to dyes and visible light, and two relatively rare but disabling conditions from ultraviolet A exposure--solar urticaria and contact photosensitivity of the photoallergic type (persistent light reaction). During the past five years, eight patients with photosensitivity induced by musk ambrette and UVA have been treated at Columbia-Presbyterian Medical Center; six of these have been severely disabled and satisfy the criteria for persistent light reactors. Fifteen patients with solar urticaria have also been observed. Ten of these had reactions in the UVA range. The clinical and laboratory findings of these two groups of patients were presented.

Expected skin complaints of the geriatric patient.

Increased exposure to systemic medications in older patients makes drug reactions a likely cause of skin eruptions. Efforts to increase return of venous blood to the heart is the primary therapeutic and preventive measure in stasis dermatitis. If there is a suggestion of infection, antibiotics are indicated. The dermatitis can be treated with standard therapies.

Ultraviolet radiation induces changes in membrane metabolism of human keratinocytes in culture.

Human keratinocytes in culture were prelabeled with [3H]arachidonic acid (AA) and then exposed to ultraviolet B radiation. Irradiated cells released labeled AA metabolites into media in a dose-dependent manner when compared to sham-irradiated cells. The response began immediately and continued for 24 h. Extracts from media were examined by high-performance liquid chromatography for identification of specific AA metabolites. Irradiated cells were stimulated to produce prostaglandin-like material (PGE2 and PGF2 alpha). These findings support the concept that the cell membrane of keratinocytes participates directly or indirectly in initiating the sunburn response. It is also felt that the metabolites formed following injury to the membrane are an integral component in the mediation of that response.

Modified Goeckerman therapy for psoriasis. A two-year follow-up of a combined hospital-ambulatory care program.

Two groups totaling 162 patients hospitalized for modified Goeckerman treatment of severe psoriasis were matched for sex, age, and season of admission and followed up for two years after discharge. One group remained hospitalized throughout their average 20.8-day course; the other half was hospitalized 14 days, then transferred to an ambulatory center for the remainder of a course averaging 20.8 days. No difference was detected between the groups in the duration that improvement equaled or exceeded progress achieved at discharge. The percentage of patients remaining continuously improved after discharge was 80% at one month, 55% at six months, 40% at 12 months, and 20% at 24 months. rates of relapse requiring readmission or alternate therapy were also similar: 75% had not relapsed by 12 months and 60% had not relapsed by 24 months.

Current status of predictive animal models for drug photoallergy and their correlation with drug photoallergy in humans.

The number of adverse responses considered to be drug photosensitivity reactions account for only an exceedingly small percentage of the total undesirable effects from environmental chemicals. However, the rising incidence of and severe disability resulting from drug photosensitivity, especially when the photosensitivity is of the persistent light reactor type, indicate that increased photobiologic research and development efforts are required. Predictive tests are an obvious approach to minimize or eliminate those chemicals showing a risk-benefit ratio that is undesirable to society in general or to an unknowing individual in particular. Animal models with predictive value for determining the risk of photoallergic contact dermatitis in humans have undergone considerable modification during the past decade. This study reports an improved experimental guinea pig model for inducing photoallergic contact dermatitis to musk ambrette. In contrast to previously described models that used Freund's adjuvant, this model does not require nuchal stripping with cellophane tape. Control studies for primary irritancy, phototoxicity, allergic contact dermatitis, and "angry back" syndrome were included in the experimental design. Only photoallergic contact dermatitis was observed. Although the technique used to demonstrate this phenomenon is conducive to standardization, additional studies are required to ascertain whether or not other chemicals known to be photoallergic in humans can also be demonstrated with this animal model.

Solar urticaria. Clinical features and wavelength dependence.

Solar urticaria, an uncommon photosensitivity disorder, may be disabling for affected patients, especially those who react after short exposures to artificial or natural light. The spectrodermograph, a newly developed instrument, permits rapid, accurate determination of the action spectrum of solar urticaria. It consists of a xenon arc lamp with an emission dispersed into used to establish the wavelengths responsible for solar urticaria in 12 patients during the past four years. Knowledge of the wavelengths responsible for producing the urticarial reaction has implications for selecting appropriate therapy. The clinical course of these patients is also reviewed.