2,4,6-triarylchalcogenopyrylium dyes related in structure to the antitumor agent AA1 as in vitro sensitizers for the photodynamic therapy of cancer.

Cationic chalcogenopyrylium dyes 2-4 were synthesized in six steps from 4-(dimethylamino)phenylethyne (7), have absorption maxima in methanol of 594, 631, and 672 nm, respectively, and generate singlet oxygen with quantum yields [Phi((1)O(2))] of 0.020, 0.064, and 0.037, respectively. Dyes 2-4 are hydrolytically more stable than other chalcogenopyrylium dyes evaluated previously as sensitizers for photodynamic therapy. At 10 microM final concentration, all dyes 2-4 inhibited cytochrome c oxidase during irradiation of tumor mitochondrial suspensions treated with 10 microM dye. The degree of enzyme inhibition was abated in a reduced oxygen environment and in the presence of imidazole, a singlet oxygen trap. Superoxide dismutase, at a final concentration of 30 U, did not alter the photosensitized inhibition of mitochondrial cytochrome c oxidase by dyes 2-4. These data suggest that singlet oxygen may play a major role in the photosensitized inhibition of mitochondrial cytochrome c oxidase. Irradiation of R3230AC rat mammary adenocarcinoma cells in the presence of dyes 2-4 caused a significant loss in cell viability with thiopyrylium dye 2 displaying the greatest phototoxicity. Initial acute toxicity studies in vivo demonstrate that, at 10 mg/kg, none of the three dyes displayed overt toxicity.

A selenopyrylium photosensitizer for photodynamic therapy related in structure to the antitumor agent AA1 with potent in vivo activity and no long-term skin photosensitization.

Cationic chalcogenopyrylium dyes 5 were synthesized in six steps from p-aminophenylacetylene (9), have absorption maxima in methanol of 623, 654, and 680 nm for thio-, seleno-, and telluropyrylium dyes, respectively, and generate singlet oxygen with quantum yields [Phi((1)O(2))] of 0.013, 0.029, and 0.030, respectively. Selenopyrylium dye 5-Se was phototoxic to cultured murine Colo-26 and Molt-4 cells. Initial acute toxicity studies in vivo demonstrate that, at 29 mg (62 micromol)/kg, no toxicity was observed with 5-Se in animals followed for 90 days under normal vivarium conditions. In animals given 10 mg/kg of 5-Se via intravenous injection, 2-8 nmol of 5-Se/g of tumor was found at 3, 6, and 24 h postinjection. Animals bearing R3230AC rat mammary adenocarcinomas were treated with 10 mg/kg of 5-Se via tail-vein injection and with 720 J cm(-2) of 570-750-nm light from a filtered tungsten lamp at 200 mW cm(-2) (24 h postinjection of 5-Se). Treated animals gave a tumor-doubling time of 9 +/- 4 days, which is a 300% increase in tumor-doubling time relative to the 3 +/- 2 days for untreated dark controls. Mechanistically, the mitochondria appear to be a target. In cultured R3230AC rat mammary adenocarcinoma cells treated with 0.1 and 1.0 microM 5-Se and light, mitochondrial cytochrome c oxidase activity was inhibited relative to cytochrome c oxidase activity in untreated cells. Irradiation of isolated mitochondrial suspensions treated with 10 microM dye 5-Se inhibited cytochrome c oxidase activity. The degree of enzyme inhibition was abated in a reduced oxygen environment. Superoxide dismutase, at a final concentration of 30 U, did not alter the photosensitized inhibition of mitochondrial cytochrome c oxidase by dye 5-Se. The data suggest that singlet oxygen may play a major role in the photosensitized inhibition of mitochondrial cytochrome c oxidase.

Synthesis and evaluation of chalcogenopyrylium dyes as potential sensitizers for the photodynamic therapy of cancer.

A series of thiopyrylium (2), selenopyrylium (3), and telluropyrylium dyes (4) was prepared via the addition of Grignard reagents to either 2, 6-di(4-dimethylamino)phenylchalcogenopyran-4-ones (5a) or 2-[4-(dimethylamino)phenyl]-6-phenylchalcogenopyran-4-ones (5b) followed by elimination and ion exchange to give the chloride salts. The absorption spectra and quantum yields for singlet oxygen generation of these dyes suggested that the dyes would have utility as sensitizers for PDT. Selenopyrylium dyes 3a and 3d with quantum yields for singlet oxygen generation of 0.040 and 0.045, respectively, were phototoxic to Colo-26 cells in culture. The toxicity of the dyes 2-4 was evaluated in clonogenic assays of human carcinoma cell lines. Importantly, the presence of a sulfur, selenium, or tellurium heteroatom in the molecules had no predictable impact on the toxicity of any particular dye set. Substituents at the 2-, 4-, and 6-positions of the dye had a much greater impact on cytotoxicity. The IC(50) values determined in the clonogenic assays did not correlate with chemical properties in the dye molecules such as reduction potential or lipophilicity. Initial in vivo toxicity studies showed no toxicity for these dyes at dosages between 7.2 and 38 micromol/kg in BALB/c mice.

Immunohistologic demonstration of myocardial proteins with applications.

The authors used antibodies specific for creatine kinase MB isoenzyme (CK-MB) and myosin light chain-1 (MLC-1) for immunohistologic staining. At appropriate dilutions of antibody, frozen sections of human heart muscle were positive for both CK-MB and MLC-1, whereas sections of human skeletal muscle were negative for both proteins. Staining for both CK-MB and MLC-1 also was demonstrated in an immature teratoma. Furthermore, staining was localized to the rhabdomyosarcomatous elements within the teratoma; other components of the tumor did not stain for CK-MB or MLC-1. Biopsies of skeletal muscle revealed that regenerative, but not intact normal or degenerating, fibers also contained CK-MB and MLC-1. Immunohistologic stains for CK-MB and MLC-1 may be useful as tumor markers and as markers for regenerative muscle fibers.

Firearm deaths in Canadian adolescents and young adults.

This article describes the problem of firearm deaths among Canadians aged 15-24 years. It is based on data obtained from Statistics Canada, the Metropolitan Toronto Police Department, and the Canadian Department of Justice. Firearms are the third leading cause of death in this age group, accounting for 276 deaths in 1990, after motor vehicle accidents (997) and non-firearm suicides (358). Some 23% of Canadian homes contain a firearm; the average number of firearms per home is 2.67. Medical and public health professionals are urged to work toward prevention by educating patients and families about the risks of a firearm in the home and by supporting legislation to decrease the availability of firearms to young people.

Multimodal imaging does not delay intravenous thrombolytic therapy in acute stroke.

BACKGROUND AND PURPOSE: Patients with acute ischemic stroke require immediate medical treatment, and a CT to rule out hemorrhage is required before tPA. We adapted our protocol to include multimodal CT: unenhanced CT, CTA, and PCT. The purpose of this study was to determine whether multimodal CT imaging delays initiation of IV tPA beyond 60 minutes from hospital arrival. MATERIALS AND METHODS: All patients admitted during 3 years through the ED with a stroke alert and time from symptom onset to hospital arrival <2.5 hours were included. We examined 2 subgroups (multimodal CT versus unenhanced CT) to determine whether multimodal CT delayed tPA administration. Logistic regression was used to identify variables that predicted tPA within 60 minutes. RESULTS: There were 123 patients in the analysis, including 108 patients who were examined with multimodal CT. The median time from arrival to tPA was 56 minutes and was shorter for patients examined with multimodal CT (55 versus 78 minutes, P = .02). After adjustment, variables that were associated with tPA administration within 60 minutes included prehospital stroke alert (OR = 3.47, P = .03), time to CT (OR = 0.94, P = .01), and onset-to-arrival time (OR = 1.02, P = .04). There was no statistically significant difference in the odds of receiving timely tPA for multimodal versus unenhanced CT (OR = 3.99, P = .07). CONCLUSIONS: In our single-center experience, the use of multimodal imaging in patients with acute stroke did not delay IV tPA beyond 60 minutes. Further study is needed to assess the feasibility of the routine use of multimodal imaging in the acute stroke setting.

Combinatorial chemistry in cancer drug development.

The field of combinatorial chemistry has grown at an enormous rate in recent years, both in response to high-throughput capabilities and the discovery of a plethora of novel therapeutic targets. This review attempts to outlinethe recent developments of combinatorial chemistry in the search for novel cancer-related therapeutic agents.

Secretion of creatine kinase MB isoenzyme by an immature teratoma with predominant rhabdomyosarcomatous elements.

A 37-year-old man with metastatic immature (malignant) teratoma with prominent rhabdomyosarcomatous elements had markedly increased activity of creatine kinase (EC 2.7.3.2) MB in serum. There was no electrocardiographic evidence of infarction or ischemia, and autopsy revealed no myocardial infarction, significant coronary atherosclerosis, myocarditis, or invasion of the heart by tumor. A high proportion of the creatine kinase activity in a homogenate of the tumor was attributable to the MB isoenzyme. Persistent increases of creatine kinase-MB and an unusually high MB isoenzyme activity, out of proportion to total creatine kinase activity, may indicate a nonmyocardial origin of this isoenzyme.