Changes in the phenotype of human small cell lung cancer cell lines after transfection and expression of the c-myc proto-oncogene

Small cell lung cancer growing in cell culture possesses biologic properties that allow classification into two categories: classic and variant. Compared with classic small cell lung cancer cell lines, variant lines have altered large cell morphology, shorter doubling times, higher cloning efficiencies in soft agarose, and very low levels of L dopa decarboxylase production and bombesin-like immunoreactivity. C-myc is amplified and expressed in some small cell lung cancer cell lines and all c-myc amplified lines studied to date display the variant phenotype. To investigate if c-myc amplification and expression is responsible for the variant phenotype, a normal human c-myc gene was transfected into a cloned classic small cell lung cancer cell line not amplified for or expressing detectable c-myc messenger RNA (mRNA). Clones were isolated with one to six copies of c-myc stably integrated into DNA that expressed c-myc mRNA. In addition, one clone with an integrated neo gene but a deleted c-myc gene was isolated and in this case c-myc was not expressed. C-myc expression in transfected clones was associated with altered large cell morphology, a shorter doubling time, and increased cloning efficiency, but no difference in L dopa decarboxylase levels and bombesin-like immunoreactivity. We conclude increased c-myc expression observed here in transfected clones correlates with some of the phenotypic properties distinguishing c-myc amplified variants from unamplified classic small cell lung cancer lines.

Non-small-cell lung cancer. Major cause of late mortality in patients with small cell lung cancer

Among 360 patients with small cell lung cancer treated in National Cancer Institute therapeutic trials from 1973 to 1982, 40 were two-year cancer-free survivors. Of these 40 patients, six had later development of non-small-cell lung cancer at 3.5 to 8.0 years (median 5.1) after the diagnosis of small cell lung cancer. Three had the second malignant tumor in the contralateral lung, one in a different lobe, and two in the same lobe as the initial small cell lung cancer. Ten patients had relapses of small cell lung cancer at 2.1 to 6.2 years (median 3.2) from diagnosis. Three recurrences were in the same site or lobe as the initial lesion, four in the same lobe and in sites outside the thorax, and three solely in sites outside the thorax. It is concluded that these non-small-cell lung cancers usually represent second primary lung tumors and that most late small cell lung cancers represent relapses occurring up to 6.2 years from diagnosis. In this study, the risk of development of non-small-cell lung cancer after two years of disease-free survival following small cell lung cancer is 4.4 percent per person-year, approximately 10 times higher than the rate of 0.5 percent previously determined in screening studies of men at high risk for lung cancer. Non-small-cell lung cancer represents more than a third of lung cancer deaths in patients with small cell lung cancer surviving beyond two years from diagnosis and more than half of lung cancer deaths beyond three years. It is recommended that all patients treated for small cell lung cancer discontinue smoking.

Molecular genetic analysis reveals chromosomal deletion, gene amplification, and autocrine growth factor production in the pathogenesis of human lung cancer

These studies of lung cancer suggest that a number of molecular mechanisms may be important in the pathogenesis of lung cancer, especially SCLC. An inherited predisposition to develop SCLC may correlate with a nonfunctional, recessive allele for a gene (McKusick #18228, McKusick 1986) that maps to chromosome region 3p(14-23). Individuals at risk would be heterozygous for this allele in their germ line, carrying one copy of a normal functional gene and one mutant, recessive allele. Exposure to carcinogens, in particular cigarette smoke, can produce somatic genetic changes such as chromosomal deletion or gene mutation in the functional allele of this gene, unmasking the nonfunctional allele. Loss of this normal gene may alter the regulation of cell growth, perhaps by allowing the deregulated expression of proto-oncogenes of the myc family, or autocrine growth factors such as GRP and/or its receptor. Alternatively, loss of this gene may result in the cell returning to a less differentiated developmental state where growth regulation is less stringent. Persons with this mutant gene should be at increased risk to develop SCLC, and further RFLP analysis of the 3p region in SCLC may allow identification of specific haplotypes with increased risk of developing lung cancer. If this notion is correct, one might expect to find an increased frequency of second tumors in lung cancer patients and the presence of similar chromosomal deletions in second tumors arising in SCLC patients. In this regard, cured lung cancer patients, including those with SCLC, have a tenfold increased risk of developing a second lung cancer (Fontana 1977; Cortese et al. 1983; Johnson et al. 1986b). In fact, a chromosome 3p deletion along with other chromosomal abnormalities was identified in acute erythroleukemia cells arising in a long-term survivor of SCLC (Bradley et al. 1982), implicating this same region in the pathogenesis of both tumors. Other predictions include the correction of at least a portion of the defect by introducing a normal chromosome 3 into SCLC cells. While c-myc is expressed in many fetal and adult tissues, high-level expression of N- and L-myc is very restricted as to tissue and stage in the developing mouse, with N-myc expressed in the fetal but not adult lung, whereas the lung was the only adult tissue where L-myc expression was detected (Zimmerman et al. 1986). Could these patterns provide a clue to the differential expression of c-, N-, and L-myc found in different lung cancers (Nau et al. 1986)?(ABSTRACT TRUNCATED AT 400 WORDS)

Neurologic, neuropsychologic, and computed cranial tomography scan abnormalities in 2- to 10-year survivors of small-cell lung cancer

In order to evaluate the relationship between neurologic function and cranial irradiation, 20 patients treated on National Cancer Institute (NCI) small-cell lung cancer (SCLC) trials who were alive and free of cancer 2.4 to 10.6 years (median, 6.2) from the start of therapy were studied. All were tested with a neurologic history and examination, mental status examination, neuropsychologic testing, and review of serial computed cranial tomography (CCT) scans. Fifteen patients had been treated with prophylactic cranial irradiation (PCI), two patients with therapeutic cranial irradiation, and three received no cranial irradiation. All patients but one were ambulatory and none were institutionalized. Fifteen patients (75%) had neurologic complaints, 13 (65%) had abnormal neurologic examinations, 12 (60%) had abnormal mental status examinations, 13 (65%) had abnormal neuropsychologic testing, and 15 (75%) had abnormal CCT scans. Compared with those given low-dose maintenance chemotherapy during PCI using 200 to 300 rad per fraction, patients who were given high-dose induction chemotherapy during the time of cranial irradiation or large radiotherapy fractions (400 rad) were more likely to have abnormal mental status examinations (6/6 v 4/9) and abnormal neuropsychologic tests (6/6 v 4/9), but no major difference in CCT findings was present. CCT scans in the majority of cases (11/18) showed progressive ventricular dilatation or cerebral atrophy up to 8 years after stopping therapy. We conclude neurologic abnormalities are common in long-term survivors of SCLC, and may be more prominent in patients given high-dose chemotherapy during cranial irradiation or treated with large radiotherapy fractions. The CCT scan abnormalities are common and progressive years after prophylactic cranial irradiation and chemotherapy are stopped.

A study of cutaneous photosensitivity induced by amiodarone

Amiodarone-induced cutaneous photosensitivity was studied in 12 subjects treated with the drug. The action spectrum for the abnormal response to sunlight was shown to be within the range of 335-460 (+/- 30) nm. The clinical features of the photosensitivity response suggested that it was most probably a phototoxic reaction, a conclusion supported by the results of in vitro studies which indicated activity mainly against cell membranes. Of the five in vitro models used, three--namely photohaemolysis, the inhibition of DNA synthesis in PHA stimulated lymphocytes and the killing of mouse peritoneal macrophages--provided unequivocal evidence of the phototoxic potential of both amiodarone and its major metabolite, desethylamiodarone. In each model desethylamiodarone produced a greater effect by a factor of between 2 and 10. In vitro, UV-B wavelengths produced a greater effect than UVA but the difference between the effective wavelengths in vivo and in vitro might be explained by the greater absorption of the shorter wavelength UV-B in the epidermis. Zinc oxide-containing preparations appeared to be the most effective in reducing the cutaneous photosensitivity. It is suggested that the long-term cutaneous pigmentation resulting from oral amiodarone has a significant photosensitivity component.

Patients with small-cell lung cancer treated with combination chemotherapy with or without irradiation. Data on potential cures, chronic toxicities, and late relapses after a five- to eleven-year follow-up

We assessed the outcome in 252 patients with small-cell lung cancer 5 to 11 years after treatment with combination chemotherapy, with or without chest and cranial irradiation, in National Cancer Institute therapeutic trials from 1973 through 1978. Twenty-eight patients (11%) survived free of cancer for 30 months or more. Fourteen patients remain alive without evidence of cancer beyond 5 years (range, 6.4 to 11.3 years), and 7 patients have returned to a lifestyle similar to that before diagnosis. The other 14 patients who were cancer-free at 30 months have developed cancer or died; 6 patients had a relapse, 4 developed or died from non-small-cell lung cancer, and 4 died of unrelated causes. A few patients with small-cell lung cancer (5.6%) may be cured. Thirty-month, cancer-free survival is insufficient to show a cure. Although late toxicities are troublesome, they do not outweigh the benefits of prolonged survival and potential for cure with modern aggressive therapy in small-cell lung cancer.

The action spectrum for benzanthrone photosensitization of mouse macrophages

An in vitro method for determination of the phototoxic action spectrum of benzanthrone was established using a cover slip-test tube culture system with mouse peritoneal macrophages. The action spectrum peaked between 380 and 400 nm with abrupt fall-off to either side. These findings correlate closely with both the absorption spectrum of benzanthrone and the clinical action spectrum of phototoxicity in humans.

Comparative mutagenicity tests in the Salmonella/microsome assay with rat and woodchuck S9 preparations

The Salmonella mutagenicity assay was utilized to compare the hepatic S9 fractions from untreated and 3-methylcholanthrene (MC) induced woodchucks with Aroclor 1254 induced rats. Three known promutagens, benzo[a]pyrene (BP), 7,12-dimethylbenz[a]anthracene (DMBA), and 2-aminofluorene (AF) were tested at 5 concentrations with the strain TA100 against 3 levels of S9 fraction. Both woodchuck S9 fractions were as effective as the rat S9 in activating BP and both were more effective than the rat S9 in activating DMBA. Untreated woodchuck S9 was also as effective as rat S9 in activating AF. The protein content of the S9 fraction did not differ significantly between rats and woodchucks, but the P-450 content of the rat S9 was approximately 3.5 times that of woodchuck.

A study of compositae plant extract reactions in photosensitivity dermatitis

In subjects with chronic photosensitivity of the photosensitivity dermatitis/actinic reticuloid type the persistent reaction of the skin appears to be due to a number of factors, including those of contact allergic sensitivity and of photosensitivity (i.e., phototoxicity and/or photoallergy). The assessment of the relevant importance of these factors can be complicated by the reactivity of the skin resulting in false positive responses from skin patch and photopatch testing. Moreover, difficulties may also arise in the assessment of the results using commercially available patch test materials. However, the study described here indicated that, provided the reactivity of the skin is suppressed prior to investigation, reliable results are obtained from photopatch testing and that these results are similar whether the extract is from a commercial source or has been obtained from locally grown Compositae plants. Also, that although there may be a photoallergic component in the cutaneous photosensitivity, the results of the in vivo and in vitro studies reported here indicate the likely involvement of phototoxicity as well.

Effect of inhaled glycopyrrolate and atropine in asthma. Precipitated by exercise and cold air inhalation

We compared the effects of inhaled glycopyrrolate (G), 1.3 mg, and atropine (A), 2.6 mg, and placebo on FEV1 and specific conductance (sGaw) before and after exercise in six men with exercise-induced asthma. Subjects exercised with cold air (-2 degrees C) 30 and 120 minutes after each aerosol treatment. Spirometry was performed and sGaw determined before aerosol treatment (baseline) and before and after exercise. Decreased airway tone was noted before exercising with A and G but not with placebo. The decreases in FEV1 and sGaw resulting from exercise were not significantly different among the three treatment groups at either exercise session. Postexercise FEV1 and sGaw were significantly higher after A and G compared to P. Dry mouth, flushing, and resting tachycardia were prominent with group A. Symptoms in G did not differ from those in P. This study suggests that A and G do not prevent bronchoconstriction induced by exercise and cold air but improve postexercise pulmonary function by achieving preexercise bronchodilation. Systemic side effects were minimal with G compared to A.

Purification, biochemical characterization, binding activity, and selectivity of a glutamate binding protein from bovine brain

A glutamate binding protein was purified from bovine brain to apparent homogeneity. The procedure used for the purification of this protein involved extraction of a crude synaptic membrane fraction with Na-cholate, followed by solubilization of the binding protein from the membranes by Triton X-100, and, finally, affinity batch separation of the protein on L-glutamate-loaded glass fiber. The molecular characteristics of the purified protein were similar to those previously described for the glutamate binding protein from rat brain synaptic membranes and included the following: small Mr (14,000), acidic (pI = 4.7) protein with a single NH2-terminal amino acid (tyrosine), and significant absorption at wave-lengths greater than 300 nm. Complete amino acid analysis of the protein was not achieved, either because of destruction of some amino acids or of incomplete hydrolysis of the protein. The protein bound L-glutamate with high affinity (KD = 0.87 microM), exhibited one class of L-glutamate binding sites, and bound glutamate with a stoichiometry of 0.7 mol ligand/mol protein. The displacement of protein-bound L-glutamic acid by other neuroactive amino acids had characteristics similar to those observed for the displacement of L-glutamate from rat brain synaptic membrane or purified protein binding sites. Finally, the metal ligand formers KCN and NaN3 inhibited the activity of this protein just as they have been shown to do in rat brain synaptic membranes or the purified protein.

Prolongation of the prodrome to acute hepatitis B infection by corticosteroids

A 56-year-old woman had rash, arthralgia, and lymphadenopathy. Prednisone therapy caused the symptoms to abate but not disappear. Medication was continued for almost eight weeks, during which time the symptoms persisted. While the patient was receiving therapy, serologic evidence of hepatitis B infection was noted. When prednisone therapy was stopped, the patient rapidly passed from the prodrome to typical, acute, icteric hepatitis. Prednisone may have suppressed normal immunologic responses to the hepatitis virus, resulting in persistence of the serum sickness-like state. Corticosteroids are not indicated in the treatment of the prodrome to hepatitis B infection.

Furocoumarins of Heracleum laciniatum: isolation, phototoxicity, absorption and action spectra studies

Isolation of the furocoumarins (psoralens) bergapten, isobergapten, sphondin, isopimpinellin and pimpinellin from the Umbilliferous plant Heracleum laciniatum was carried out by column chromatography, and the structure and absorption spectra for the 5 furocoumarins isolated are described. Photoepicutaneous testing showed the strongest phototoxic effects from bergapten, marked effects from pimpinellin, weak effects from sphondin and none from the others. These in vivo findings were confirmed by the in vitro Candida test. Action spectrum studies demonstrated peak photosensitivity in the range 330-335 nm, bergapten being more than twice as phototoxic as pimpinellin.

Geomelophagia. An unusual pica in iron-deficiency anemia

A patient with lung cancer treated by radiation and in remission presented with a two-month history of compulsive eating of raw, chilled potatoes. Suspicion of a pica due to iron-deficiency anemia was confirmed after complete laboratory evaluation. The source of iron loss was found to be gastrointestinal bleeding. Therapy with iron sulfate was begun, with a subsequent increase in the hemoglobin level; the pica ceased within one week of initiation of therapy. If searched for, pica is a common manifestation of iron deficiency; however, this patient apparently represents the first report of geomelophagia. Appropriate investigation of compulsive eating habits might lead to the diagnosis of iron deficiency and also allay patients' anxieties toward their behavior.

Tanning, protection against sunburn and vitamin D formation with a UV-A 'sun-bed'

There are many types of sun-beds, sun-benches and sun-panels containing fluorescent tubes which, because of their predominantly UV-A emission, are advertised to the public as a means of obtaining a tan without sunburn. This study reports the effects of a sun-bed on skin colour, on the protection afforded against sunburn, and on vitamin D formation. Side-effects are also recorded. It was shown that the sun-bed emits mainly UV-A but very little UV-B and some tanning occurred in most subjects. However, no correlation was observed between the subjects' stated ability to tan and the degree of pigmentation achieved at the end of the treatment. Most subjects also had itching and erythema, and three had polymorphic light eruption. Although very little UV-B irradiation was present, a significant increase in serum levels of 25-hydroxyvitamin D occurred, and possible explanations of this surprising finding are discussed. While the sun-bed proved popular with the subjects, only a modest tan was achieved and the incidence of side-effects appeared to limit the value of this type of appliance, especially with regard to the prevention of vitamin D deficiency.

The relationship between exposure to fragrance materials and persistent light reaction in the photosensitivity dermatitis with actinic reticuloid syndrome

Contact allergic sensitivity to allergens such as plants of the Compositae family is a feature of the chronic skin reaction seen in the photosensitivity dermatitis with actinic reticuloid syndrome. In fifty patients with this syndrome an increased incidence of contact allergic sensitivity to some common fragrance materials was demonstrated. Evidence is also presented, both by in vitro and in vivo studies, which indicates that a phototoxic mechanism is involved. The relevance of continued exposure to common allergens and their involvement in photosensitization mechanisms is discussed in an attempt to explain the state of 'persistent light reaction'.

Myelosuppression in Legionnaires' disease

A patient undergoing examination for moderately severe renal insufficiency had fulminant five-lobed pneumonia caused by Legionella pneumophila. Her clinical course was complicated by granulocytopenia. Bone marrow aspiration showed notable inhibition of myelopoiesis, involving all stages of maturation. The presence of a serum inhibitor of granulopoiesis was demonstrated by in vitro bone marrow culture. Normal bone marrow cultured in the presence of serum from two normal control subjects yielded 69 +/- 5.2 (mean +/- SE) and 61 +/- 5 granulocyte colonies. When the patient's serum was substituted for normal human serum only 14.3 +/- 2.3 colonies were formed. Each of the drugs to which she had been exposed was tested in the in vitro system, using therapeutic concentrations, and none showed significant suppression of granulocyte colony formation. These observations indicate that legionnaires' disease was associated with a serum factor that notably inhibited the growth of granulocyte colonies in this patient.

Chemical location of cadmium in developing rat molars

The purpose of this experiment was to determine the distribution and chemical binding of 109Cd in the developing rat molar. The results indicated that cadmium was taken up into the inorganic fraction of molar teeth, and this may help elucidate the mechanism of caries promotion by cadmium.

Vitamin D nutrition in relation to season and occupation

Seasonal variations in vitamin D nutrition were assessed by measurements of serum 25-hydroxycholecalciferol levels in outdoor workers, indoor workers and long-term hospital inpatients. All three groups showed seasonal changes and the outdoor workers had, as might be expected, the highest levels at all seasons. However, the highest levels of 25-hydroxycholecalciferol were found in October in the indoor workers and in November for the outdoor workers whereas the peak in ultraviolet exposure was in July. The possible reasons for this long lag are discussed; the most likely explanation is that vitamin D continues to be formed and stored during the autumn especially in outdoor workers.

Anterior tibial compartment syndrome following use of MAST suit

A case of anterior tibial compartment syndrome following the use of the military antishock trousers (MAST) suit is reported. Early recognition of this complication is necessary to ensure a good outcome. Monitoring of the MAST pressure and use of the lowest pressure that is effective may decrease the likelihood of this complication.

Commercially available sun lamps and vitamin D formation

Four commercially available, medium pressure mercury sun lamps were used to assess their effects on promoting vitamin D synthesis in the skin. It was found that all the lamps studied had vitamin D synthesizing spectral wavelengths and caused an increase in the serum concentrations of 25-hydroxyvitamin D. However, the ultraviolet and visible irradiance measurements showed that a considerable proportion of the ultraviolet radiation was below 290 nm. It was not surprising, therefore, to find that these lamps caused adverse skin reactions. While a useful rise in vitamin D production can be obtained with these sun lamps, the difficulty involved in avoiding skin reaction limits their usefulness. Such lamps are unlikely to provide a safe practical routine method for the prevention of vitamin D deficiency in the home.

Plasma 8-methoxypsoralen concentrations in photochemotherapy of psoriasis

A quantitative study of 8-methoxypsoralen plasma profiles in patients with psoriasis undergoing photochemotherapy shows that a poor response to the treatment may be explained in terms of abnormal pharmacokinetic behaviour. However, not all 'poor responders' exhibit an abnormal pattern and for these an alternative explanation is required.

Sister chromatid exchange and chromosome aberration rates in a group of psoriatics before and after a course of PUVA treatment

Blood was cultured and chromosome preparations were examined for sister chromatid exchanges and chromosome aberrations in eighteen patients receiving photochemotherapy with 8-MOP and UV-A for the treatment of psoriasis, both before starting treatment and again 6 months later. The UV-A was administered both by means of low output (irradiance: 1.1--2.25 mW/cm2) and high output (irradiance: 6.1--7.6 mW/cm2) UV-A radiation cubicles. Irrespective of the intensity of irradiation or the total dose of UV-A administered there was no evidence of chromosome damage in lymphocytes following treatment.

Possible value of fluorescent lighting in the prevention of vitamin D deficiency in the elderly

Osteomalacia due to vitamin D deficiency is common in elderly women. It has been suggested that ultraviolet light may have a place in its prevention but our studies with Vita-Lite fluorescent tubes have given no support to the view that these can play a useful role in the promotion of vitamin D synthesis.

Contact allergic sensitivity to chrysanthemum and the photosensitivity dermatitis and actinic reticuloid syndrome

Of sixty-nine examples of the photosensitivity dermatitis and actinic reticuloid syndrome, nine were found to be allergically sensitive to chrysanthemum oleoresin extract. Although this extract showed evidence in vitro of a phototoxic action we were unable with in vivo studies to explain the connection between the contact allergic sensitivity and the photosensitivity. The fractions responsible for the in vitro phototoxicity appear to be different from those involved in the in vivo contact allergic sensitivity. This study provides further support for the view that in the photosensitivity dermatitis and actinic reticuloid syndrome contact allergic sensitivity is of importance.

Contact allergic sensitivity to plants and the photosensitivity dermatitis and actinic reticuloid syndrome

Contact allergic sensitivity to oleoresin extracts from Compositae plants was found to be usually present in individuals suffering from the photosensitivity dermatitis and actinic reticuloid syndrome. It was demonstrated in forty-seven out of fifty-five examples of this syndrome. These results provide support for the view that contact allergic sensitivity is an important aspect of the state of chronic photosensitivity in the middle-aged and elderly male.

Dose response, wavelength dependence and rate of excision of ultraviolet radiation-induced pyrimidine dimers in mouse skin DNA

The yield of thymine-containing dimers produced in mouse skin DNA in vivo by 290 nm ultraviolet radiation was shown to increase with dose up to around 2000 J/m2 and subsequently at a much slower rate up to 8000 J/m2. The study of wavelength dependence of dimer formation in skin indicated that 290 nm was the most effective wavelength of those investigated, followed by 300, 280 and 260 nm, with 310 nm being by far the least effective. A reduction in the number of dimers present in skin DNA was shown to occur by 24 h post-irradiation in a dose-dependent manner. A significant percentage of the dimers was, however, found to persist in the skin until at least 72 h post-irradiation.

The treatment of erythropoietic protoporphyria. Experience with beta-carotene

In a group of 19 subjects suffering from erythropoietic protoporphyria the administration of beta-carotene appeared to produce improvement based on a subjective assessment of alterations in exposure times required to produce the symptoms and signs of the condition. This clinical improvement however failed to show a direct correlation with the prophyrin levels in blood and faeces, or with the estimation by phototesting of the minimal response dose within the action spectrum of 400-600 nm.

Sister chromatid exchanges in lymphocytes of psoriatics after treatment with 8-methoxypsoralen and long wave ultraviolet radiation

Sister chromatid exchange rates in cultured cells from the blood of patients receiving photochemotherapy have been examined as an indicator of possible genetic hazards of the treatment to patients with psoriasis. Lymphocytes of untreated patients with psoriasis appear to have sister chromatid exchange rates after 72 h of culture indistinguishable from normal subjects and there is no evidence from these studies that sister chromatid exchanges are significantly increased in the lymphocytes of patients receiving photochemotherapy. Cells from blood taken from patients who had been given 8-methoxypsoralen orally 2 h before and then irradiated with UV-A in vitro were found to have an increased exchange rate which could be related to the presence of the drug in the peripheral circulation.

A study of oil of bergamot and its importance as a phototoxic agent. II. Factors which affect the phototoxic reaction induced by bergamot oil and psoralen derivatives

Using a standardized open photopatch test technique, the phototoxic reactions produced by bergamot oil bergapten (5-methoxypsoralen) the active component of the oil, and xanthotoxin (8-methoxypsoralen) were studied. The reaction was affected by a range of factors such as the vehicle (PMF or ethanol), the concentration of ethanol in the vehicle, the skin site, the interval between application of the psoralen and irradiation, the hydration of the skin, and the degree of natural or sun-induced pigmentation. Repeated photopatch testing at the same skin site produced an increase in sensitivity. Eye colour, natural susceptibility to suntanning, age, and sex, had no effect on the phototoxic response to psoralens.

Sister chromatid exchanges in human lymphocytes exposed to 8-methoxypsoralen and long wave UV radiation prior to incorporation of bromodeoxyuridine

Human lymphocytes exposed to the effects of long wave UV radiation in the presence of 8-methoxypsoralen prior to stimulation by PHA show dose related sister chromatid exchanges after 2 replication cycles in vitro. This has implications for interpreting the processes involved and for monitoring DNA damaging agents in vivo.

Photochemotherapy in the treatment of psoriasis

This article describes the satisfactory clinical improvement obtained in the majority of a group of 72 patients with psoriasis of various types as a result of the oral and/or topical administration of 8-methoxypsoralen followed by long wavelength ultraviolet irradiation. The irradiation source used was that of conventional longwave UV fluorescent tubes mounted in a specially constructed cubicle. Until such time as the long term effect of this form of photochemotherapy on the cell has been evaluated and the most appropriate regime worked out, it would seem to be important to restrict the amount of irradiation used to that required to produce acceptable maintained clinical improvement.

A study of oil of bergamot and its importance as a phototoxic agent. I. Characterization and quantification of the photoactive component

It is important in the technique of photopatch testing, using oil of bergamot, to have determined the concentration of the active psoralen, bergapten, so as to avoid false negative responses in the assessment of phototoxic reactions. Techniques for assessing the phototoxic components of oil of bergamot are described and quantitative analyses of bergapten, the only significant photoactive compound in the samples examined, are reported. The phototoxicity of bergapten was found to be nearly the same as that of xanthotoxin (8-MOP) in tests on human skin.

The investigation of quindoxin photosensitivity

Quindoxin (quinoxaline di-N-oxide) is a photosensitizer capable of producing photocontact dermatitis. The study of a group of seven affected subjects has provided evidence of persistent light reaction and "photoallergy", most probably to the parent substance and not to any photoproduct or contaminant. Clinical and photobiological similarities to the photosensitivity dermatitis and actinic reticuloid syndrome were demonstrated.