Relation between polyporphyrin distribution and blood brain barrier changes in the rat glioma model.

Photofrin (a polyporphyrin mixture) distribution in a rat glioma model was studied in relation to changes in the blood brain barrier (BBB). At selected intervals after intraperitoneal injection of Photofrin, the concentration of polyporphyrins (PP) and Evans Blue Dye, an indicator of BBB permeability, were determined for tumor, brain adjacent to tumor (BAT), and normal brain tissue. Contrary to earlier reports of maximal accumulation at 4-24 hours, tumor levels of PP increased throughout the 96 hour measurement period. During the early stages of tumor development, PP uptake by tumor appeared to be less correlated to BBB disruption. We conclude that passive diffusion through an incompetent BBB does not completely explain PP accumulation in tumor tissue.

Stereotactic intratumoral photodynamic therapy for recurrent malignant brain tumors.

Photodynamic therapy (PDT) using purified hematoporphyrin derivative and stereotactic intratumorally implanted optical laser fiber(s) was used to treat patients with recurrent malignant gliomas and metastatic melanoma of the brain. Tumor response to PDT was evaluated by recording changes in the volume and pattern of tumor enhancement between computed tomographic and magnetic resonance imaging scans done before and after PDT, metabolic changes in tumor tissue by 31P magnetic resonance spectroscopy, and patient outcome. Toxicity of PDT to brain was evaluated on the basis of changes in the patients' neurological examinations and correlated with changes in brain adjacent to tumor seen on postoperative imaging studies. Dramatic tumor responses to PDT were seen in all gliomas, but no response of tumor to treatment was seen with melanoma. Transient signs and symptoms of increased peritumoral cerebral edema caused by PDT were seen in all patients. Two patients suffered permanent neurological sequelae, monocular blindness and a partial visual field defect, as a result of treatment. Two patients with recurrent anaplastic astrocytomas remain in remission at 45 and 35 weeks after PDT. We conclude that intratumoral photoradiation therapy of hematoporphyrin derivative-photosensitized malignant gliomas effectively produces necrosis of the solid component of malignant gliomas; however, intratumoral photoradiation may not reach the portion of tumor that invades normal brain.

Photosensitization of human glioma cells by chalcogenapyrylium dyes.

Chalcogenapyrylium (CP) dyes which are specifically activated by red and near infrared light (600-900 nm) were examined as potential photosensitizers for photochemotherapy of malignant gliomas. Eleven CP dyes of varying chemical structure and redox potential were evaluated for selective toxicity against glioma and normal skin fibroblast cell cultures both before and after light activation. Eight of eleven CP dyes exhibited differential toxicity to tumor over fibroblast cells at dye concentrations of 1.0 microM. Dose dependent toxicity was seen both in the dark and after laser light activation. The toxicity of two of the CP dyes was significantly enhanced by photoactivation with 800 nm light. The CP dyes that absorb light maximally between 775 and 850 nm, in the range of excellent light penetration through brain, appear to be promising candidates as photosensitizers for treating malignant brain tumors.

The effect of a chalcogenapyrylium dye with and without photolysis on mitochondrial function in normal and tumor cells.

A chalcogenapyrylium dye 8b, which is under investigation for the photodynamic therapy of malignant gliomas (brain tumors), was evaluated for inhibition of mitochondrial function both before and after exposure to laser light of 800 nm. Neoplastic and normal cells forced to use mitochondrial substrates were killed by the light-activation of intracellular 8b as well as exposure to classic mitochondrial inhibitors, rotenone and sodium azide. Correspondingly, cells in glucose-rich media showed little decrease in viability due to the photolysis of intracellular 8b or the presence of mitochondrial toxins. The toxicity of 8b without light activation was found to be the same regardless of the cell's energy source. Measurement of cellular ATP generated during treatment also showed the photolysis of intracellular 8b to be more inhibitory towards mitochondrial function than the unactivated parent compound. We conclude that the chalcogenapyrylium dyes localize to the mitochondrion and that photoactivation results in mitochondrial injury.

Fixation of transporters in the active or inactive state.

A strategy is presented for fixing regulated transport systems in the functional or non-functional state. The advantages of this approach include the ability to distinguish between sensor and effector systems, the capacity to study transporters independently of their activating mechanisms, and the possibility of identifying membrane polypeptides that participate in the regulatory process.

Cell envelope alterations in antibiotic-sensitive and-resistant strains of Neisseria gonorrhoeae.

The cell envelopes of antibiotic-resistant and -sensitive isogenic strains of Neisseria gonorrhoeae were analyzed to determine whether acquisition of genetic loci for altered antibiotic sensitivity was accompanied by alterations in cell envelope composition. No differences in the composition of phospholipids and lipopolysaccharides were noted. Acquisition of mtr-2, which results in low-level, nonspecific increased resistance to multiple antibiotics, dyes, and detergents, was accompanied by a sevenfold increase in the amount of a minor, 52,000-molecular-weight outer membrane protein and a 32% increase in the extent of peptidoglycan cross-linking. Subsequent addition of the nonspecific hypersensitivity loci env-1 or env-2 to a strain carrying mtr-2 resulted in reversal of the phenotypic resistance determined by mtr-2 and marked reduction in both the amount of the 52,000-molecular-weight outer membrane protein and the extent of peptidoglycan cross-linking. Introduction of penB2, which results in a fourfold increase in resistance to penicillin and tetracycline, was accompanied by the disappearance of the principal outer membrane protein of the wild-type strain (molecular weight, 36,900) and the appearance of a new species of the principal outer membrane protein (molecular weight, 39,400) in the transformant.

Altered outer membrane protein in different colonial types of Neisseria gonorrhoeae.

Dark-colored colony types of Neisseria gonorrhoeae (T3 and dark variants of T1 and T2) had markedly increased amounts of an approximately 28,000-dalton outer membrane protein, as compared with light-colored colony types (T4 and light variants of T1 and T2). The presence of this protein appeared to be unrelated to piliation. The apparent molecular weight of this protein on sodium dodecyl sulfate-polyacrylamide gels varied, depending on methods used to solubilize envelope proteins. In view of the location of this protein on the outer membrane, this protein could be important to the pathogenicity or antigenicity of the organism as well as to colonial characteristics in vitro.

Growth inhibition among strains of Neisseria gonorrhoeae due to production of inhibitory free fatty acids and lysophosphatidylethanolamine: absence of bacteriocins.

Each of 50 tested strains of Neisseria gonorrhoeae produced growth-inhibitory substances that were active against most strains of gonococci or meningococci, but not against species other than the Neisseria. There were quantitative differences among different strains in production of the inhibitor and sensitivity to it, but not of sufficient magnitude to permit routine strain typing. The inhibitor was associated with the cell pellet (crude cell envelope) and was not inducible with mitomycin C. Inhibitory activity was thermostable and resisted alkali and proteolytic enzymes. The inhibitor was quantitatively recovered from whole cells by chloroform-methanol extraction. Separation of total gonococcal lipids by silica gel chromatography revealed inhibitory activity in both the free fatty acid and the phospholipid fractions. The major phospholipid, phosphatidylethanolamine, had no inhibitory activity, but monoacyl phosphatidylethanolamine, a minor phospholipid, was quite inhibitory. It is likely that the "bacteriocin" of N. gonorrhoeae strains results from the degradation of phosphatidylethanolamine to inhibitory long-chain free fatty acids and monoacyl phosphatidylethanolamine.