James L. Matthews

SENSITIVITY OF Porphyromonas AND Prevotella SPECIES IN LIQUID MEDIA TO ARGON LASER

Abstract— The phototoxicity of argon laser irradiation was studied in aqueous suspensions of Porphyromonas endodontalis (American Type Culture Collection [ATCC] 35406), Porphyromonas gingivalis (ATCC 33277), Prevotella denticola (ATCC 33184) and two strains of Prevotella intermedia (ATCC 15033 and 49046), all “black‐pigmented bacteria,” BPB, that accumulate cellular porphyrins. Several of these species have been implicated in the etiology of Periodontol disease. Non‐black‐pigmented bacteria were also studied to test the specificity of irradiation as a potential photodynamic treatment for Periodontol infections. Cell suspensions were irradiated with an argon laser at fluences of 20–200 J/cm2. When cultured in hemin‐supplemented media, ATCC 15033 was the most sensitive to irradiation. However, a second strain of the same species (ATCC 49046) was resistant. The photosensitivity of other species ranked ATCC 33277 > 35406 = 33184 = 35496. When hemin was replaced in media by hemoglobin, ATCC 33277 became resistant to irradiation. Protoporphyrin IX content in BPB cells was shown not to be a major factor determining photosensitivity. Oxygen was required during irradiation for BPB species to be affected. Non‐black‐pigmented bacteria were much less sensitive to irradiation than BPB.

Phototoxicity of argon laser irradiation on biofilms of Porphyromonas and Prevotella species

Species of Prevotella (Pr.) and Porphyromonas (Po.) and other microorganisms were cultivated as biofilms on agar medium and examined for their susceptibility to argon laser irradiation (continuous mode; wavelengths, 488-514 nm; fluences, 20-200 J cm(-2)). Fluences of 35 to 80 J cm(-2) inhibited biofilm growth in Po. endodontalis, Po. gingivalis, Pr. denticola, Pr. intermedia, Pr. melaninogenica and Pr. nigrescens. A fluence of 70 J cm(-2) did not affect biofilm growth in species of Bacillus, Candida, Enterobacter, Proteus, Pseudomonas, Staphylococcus and Streptococcus. The phototoxic effects of argon laser irradiation against Prevotella and Porphyromonas species were: (1) caused by the radiation alone; (2) modified by biofilm age; (3) dependent on the presence of atmospheric oxygen; (4) influenced by medium supplements of hemin, hemoglobin and blood; (5) greater when compared with other microbial species; (6) demonstrated without augmentation with an exogenous photosensitizer; and (7) apparently unrelated to the protoporphyrin content of the cells. Overall, these in vitro findings suggest that low doses of argon laser radiation may be effective in the treatment and/or prevention of clinical infections caused by biofilm-associated species of Prevotella or Porphyromonas.

Evidence for reduced cancellous bone mass in the spontaneously hypertensive rat.

The histomorphometric changes in the proximal tibial metaphysis and epiphyseal growth plate and midtibial shaft of 26-week-old spontaneously hypertensive rats (SHR) compared with those of the corresponding normotensive Wistar-Kyoto (WKY) rats were studied. A decrease in body weight, growth plate thickness, and longitudinal growth rate of the proximal tibial epiphysis, trabecular bone volume, trabecular thickness and number, the number of osteoblasts and osteoprogenitor cells per millimeter square surface of the proximal tibial metaphysis, periosteal and endocortical apposition rate and bone formation rate of the tibial diaphysis were observed in the SHR. Additionally, systolic blood pressure, the number of osteoclasts per millimeter square surface and average number of nuclei per osteoclast of the proximal tibial metaphysis were significantly increased. Thus, osteoclastic activity is dominant over osteoblastic and chondroblastic activity in the SHR that results in a cancellous bone deficit in the skeleton. It will require additional work to ascertain the underlying cause for this condition as several factors in the SHR with a potential for causing this change are present, including elevated parathyroid hormone (PTH), depressed 1,25-(OH)2D3, low calcium absorption, reduced body weight (reduced loading) elevated blood pressure and possibly other direct cell differences in the mutant strain. At present elevated PTH and adaptation to underloading from reduced weight are postulated to be a likely cause, but additional studies are required to test this interpretation.

4-alkylamino-3-bromo-N-alkyl-1,8-naphthalimides: new photochemically activatable antiviral compounds

The synthesis of several 3-bromo-4-alkylamino-N-alkyl-1,8-naphthalimides is described. These compounds have been shown to be effective, non-oxygen based photochemical inactivators of enveloped viruses, including herpes simplex virus and HIV.

Giant-Ceil Centrioles

The giant cell of osteoclastic origin and the giant cell produced in response to foreign bodies are characterized by multiple nuclei. Electron microscopy of these multinucleated cells reveals a special centrosphere in the osteoclast, which is not typical of other types of giant cells.

TUMOR CELL SPECIFIC DARK CYTOTOXICITY OF LIGHT‐EXPOSED MEROCYANINE 540: IMPLICATIONS FOR SYSTEMIC THERAPY WITHOUT LIGHT

Abstract— ‐Merocyanine 540 (MC540) was activated by exposure to 514 nm laser light. The light‐exposed MC540 was then mixed (in the dark) with tumor cells and normal cells to determine the antiproliferative activity. Treatment with light‐exposed MC540 resulted in 70–90% tumor cell kill from different cell lines, while 85% of the normal human mononuclear cells and 41% of the granulocyte‐macrophage colony forming cells (CFU‐GM) survived the treatment. The observed cytotoxicity of light‐exposed MC540 to the tumor cells was significantly greater (P < 0.05) than the native MC540. Results show that tumor cell specificity and cytotoxicity in the light activated dye are retained for at least 30 days. Addition of catalase and mannitol decreased the cell kill by light‐exposed compound, indicating that the observed effects may be due to reactive oxygen species. The electron micrographs of treated cells show a progression towards apoptosis in a majority of the cells. The life span of L1210 leukemia‐bearing mice treated with light‐exposed MC540 was prolonged compared to the untreated and native MC540 treated mice. High pressure liquid chromatography (HPLC) analysis of light‐exposed material shows a completely different elution profile compared to the native compound. Results presented here show that light‐exposed photoactive compounds can be used without further illumination and may have significant clinical applications. Photoactive mechanisms dependent on events other than short‐lived transient elevations in energy or singlet oxygen must be invoked to explain the reported cytotoxicity.

Hibernation activates glyoxylate cycle and gluconeogenesis in black bear brown adipose tissue

Biochemical studies on brown adipose tissue removed from a hibernating black bear and a non-hibernating control animal demonstrate that this tissue: (1) can carry out cyanide-insensitive fatty acid oxidation, and (2) possesses catalase activity and the enzyme activities unique to the glyoxylate cycle, isocitrate lyase and malate synthase. These activities are all markedly increased in brown fat obtained from the hibernating animal. Additionally, hibernation enhances the ability of the tissue to synthesize glycogen in the presence of a fatty acid substrate. The glyoxylate cycle enzymes and the ability to convert fatty acid carbons to glucose have been generally regarded as being absent from vertebrate cells and tissues.

Photodynamic inactivation of simian immunodeficiency virus

A photodynamic flow system employing a dihematoporphyrin ether (DHE) was tested for its ability to inactivate the in vitro infectivity of simian immunodeficiency virus (SICMac) at 630 +/- 5 nm with a light fluence of 5 J/cm2. Cell-free SIVMac was inactivated by photoactivated hematoporphyrin derivative in a dose-dependent fashion. Since SIVMac is closely related to human immunodeficiency virus type 2 (HIV-2) and we have previously reported the successful photodynamic inactivation of HIV-1 in cell-free medium as well as in whole human blood, this technology has the potential for the eradication of transfusion-associated acquired immunodeficiency diseases caused by the above-mentioned retroviruses.

Vascular anastomoses in the region of the mandibular symphysis.

Unilateral and bilateral mandibular resection and the treatment of compound fractures of the mandible indicate that the mandibular artery may be ligated without compromising the vitality of the tissues distal to the ligature.1-3 The exact pattern of the circulatory complex in this tissue are is not sufficiently understood to explain these findings. Hawkins3 has suggested that the vascular anastomosis across the mid-line of the mandible is limited but that the lips and the neighboring soft tissue contain many anastomotic branches of the mental and facial arteries. Ryder4 found that the canals and foramina of the mandible transmit anastomosing vessels which connect the inferior dental and sublingual arteries. MacGregor5 cannulated both mandibular arteries of the fractured jaw of a post mortem subject and reported that an anastomosis existed across the symphysis. Recently Bishop, Matthews, Dorman, and Moore6 injected thorium dioxide into the mandibular artery of dogs. Radiographic analysis revealed a minimum amount of crossover between the left and right side of the mandible with a minimum perfusion pressure. A study of the blood pressure in the cannulated mandibular arteries of dogs was therefore undertaken in an attempt to resolve these viewpoints.

Elimination of leukemic cells by laser photodynamic therapy

SummaryWe studied the effects of 514-nm laser light-induced merocyanine 540 (MC540)-mediated toxicity on both leukemic and normal bone marrow (BM) cells. Acute promyelocytic leukemia (HL-60) cells were incubated with MC540 (20 μg/ml) and exposed to 93.6 J/cm2 irradiation at a 514-nm wavelength. Normal bone marrow cells were treated under similar conditions. At this dose, 99.9999% of the leukemic cells were killed while 55% of the BM cell survived. Of the granulocyte-macrophage colony-forming cells (CFU-GM), 27% also survived this treatment. Photosensitization of a mixture of irradiated BM cells mixed with an equal number of nonirradiated HL-60 cell did not interfere with the killing of HL-60 cells. There was no significant reduction in the viability of cells when exposed to the laser light alone. In summary, laser light-induced photosensitization with MC540 has a selective cytotoxicity to leukemic cells; therefore, this procedure may be useful for purging neoplastic cells from autologous BM.