Characterization of hemolysis and hemoxidation activities by Treponema denticola

This study determined the presence of two hemolytic activities in the oral treponeme, Treponema denticola, strains ATCC 35404 (TD-4), ATCC 33520, GM-1, and MS25. These activities, referred to as hemolytic and hemoxidative (HeA, HeO, respectively), were found to be both secreted into the extracellular environment, and cell associated. The extracellular activity was associated with small molecules with relative molecular weights of < 1000 Da, and its activity was cysteine independent; the cell-associated HeA and HeO activities were associated with a molecular weight fraction > 10 kDa, and were cysteine dependent. The HeO activity of the fractionated material observed was due to the oxidation of hemoglobin to methemoglobin, and preceded the HeA lysis of the RBCs by approximately 2 h. Heating at 80 degrees C and treatment with proteinase K resulted in the complete destruction of these activities in the fraction > 10 kDa, while lipase at high concentration (800 micrograms/ml) reduced the HeA and HeO activities in the extracellular fraction by approximately 50%. Proteinase inhibitors had a variable effect on HeA and HeO activities in both extracellular and cell-associated fractions. Scanning and transmission electron microscopy revealed a progressive destruction of the RBC membrane, with membrane protrusions formed early in the interaction, which progressed to irregular holes in the membrane, and the complete loss of membrane integrity.

A treatment protocol for mandible fractures

Mandibular fracture management has evolved over several decades, and controversies exist over ideal approaches for individual fractures. Treatment choices include closed versus open techniques, reduction methods and repair, and decision concerning intermaxillary fixation. Both the patient and the fracture characteristics have an impact on these choices. Patient factors include age, mandibular bone quality, dentition, patient reliability, and associated injuries. Fracture characteristics include favorability versus unfavorability, single versus multiple, location, and infection. This study was undertaken to develop and evaluate a management algorithm to determine the best treatment of mandible fractures. Sixty-seven patients were managed at the Grady Memorial Hospital otolaryngology service. Ages ranged from 3 to 68 years and included 55 male patients and 12 female patients. Forty-three patients had multiple fractures, while 24 had single fractures. Sixty-four patients were successfully managed and had normal function on follow-up examination. Eleven patients (16.4%) had complications. These included three infections, one malunion, two malocclusions, and five marginal nerve pareses. Multiple fractures did not have a higher incidence of complication. This protocol allows an orderly approach to the successful outcome of mandibular fractures.

Natural antibody against Thomsen-Friedenreich antigen in sera of patients with carcinomas and infectious diseases

The levels of natural antibody against Thomsen-Friedenreich (TF) antigen in sera of patients with various cancers and infectious diseases were examined by an enzyme-linked immunosorbent assay (ELISA) and compared with those of healthy donors. The levels of antibody against TF antigen in sera of patients with adenocarcinomas such as gastric, pancreatic and colorectal cancers were lower than those of patients with hepatoma, pyelonephritis and pneumonia. These findings may reflect the expression of TF-antigen in adenocarcinoma tissues.

Early expression of human J chain and mu chain gene in the fetal liver

The expression of J chain and mu chain genes has been investigated during human fetal ontogeny by the polymerase chain reaction performed on liver sections. With this technique, we have been able to detect expression of J chain and mu chain in a single 6-10-microns-thick formalin-fixed paraffin-embedded section of fetal liver tissue. J chain expression reached a maximum at 16 weeks of gestation but was clearly detectable in the liver at the 6th week. Although not detectable at the 6th week, mu chain mRNA became readily detectable at 7 weeks of gestation. These results indicate that J chain expression precedes that of mu chain by at least one week. Therefore, our results imply that J chain is the first immunoglobulin-related polypeptide expressed during the embryogenesis and differentiation of B cells in the fetal liver.

Amelanotic melanoma of the oral cavity

A case of amelanotic melanoma arising in the upper molar region, which was difficult to diagnose histologically, is reported. The patient was a 79-year-old woman, who complained of a painful swelling in the gingiva of the left upper molar region. Routine histological examination showed that the lesion was composed of diffusely scattered atypical cells with round, spindle-shaped and irregular nuclei and scanty fibrous connective tissue. A fascicular arrangement was often found in the lesion, and no cancer nests were observed. Immunohistochemical study demonstrated positive staining for S-100 protein in both the nuclei and cytoplasm of the tumor cells. Electron microscopic examination revealed that cell organelles were abundant, and an interrupted basal lamina was often found along the cell membrane. The preliminary diagnosis was a non-epithelial malignant tumor. After surgery, histological examination of metastases in lymph nodes from the submandibular region revealed that the tumor cells contained melanin pigment in the cytoplasm, as confirmed by Masson's melanin stain. The final pathological diagnosis was therefore amelanotic melanoma. Immunohistochemical staining for S-100 protein may be useful for differential diagnosis of amelanotic melanoma in conjunction with electron microscopic examination.

Regulation of the Staphylococcus aureus plasmid pI258 mercury resistance operon

Experiments involving fusion between the Staphylococcus aureus plasmid pI258-encoded mer operon and the reporter gene beta-lactamase, mutational analysis, and trans-complementation studies have shown that the merR gene of pI258, which shows DNA sequence similarity with known merR genes from other bacteria, regulates the expression of the mer operon in vivo. The merR gene product is a trans-acting protein that activates mer operon transcription in the presence of the inducers Hg2+ and Cd2+. A glutathione-S-transferase-MerR fusion protein specifically bound and protected a 27-nucleotide operator sequence from DNase I digestion. This operator sequence is highly homologous with mer operator sequences of other known systems.

Nucleotide sequence and expression of the algE gene involved in alginate biosynthesis by Pseudomonas aeruginosa

Alginate (Alg), a random polymer of mannuronic acid and glucuronic acid residues, is synthesized and secreted by Pseudomonas aeruginosa primarily during its infection of the lungs of cystic fibrosis patients. The molecular biology and biochemistry of the enzymatic steps leading to the production of the Alg precursor GDP-mannuronic acid have been elucidated, but the mechanism of polymer formation and export of Alg are not understood. We report the nucleotide sequence of a 2.4-kb DNA fragment containing the algE gene, previously designated alg76, encoding the AlgE protein (Mr 54,361) that is believed to be involved in these late steps of Alg biosynthesis. Expression of algE appears to occur from its own promoter. The promoter region contains several direct and inverted repeat sequences and shares structural similarity with promoters of several other alg genes from P. aeruginosa. In addition, the AlgE protein was overproduced from the tac promoter in P. aeruginosa. N-terminal amino acid sequence analysis showed that the polypeptide contains a signal peptide which is cleaved to form the mature protein during AlgE export from the cell cytoplasm.

Hemolytic activity in the periodontopathogen Porphyromonas gingivalis: kinetics of enzyme release and localization

Porphyromonas gingivalis W50, W83, A7A1-28, and ATCC 33277 were investigated for their abilities to lyse sheep, human, and rabbit erythrocytes. All of the P. gingivalis strains studied produced an active hemolytic activity during growth, with maximum activity occurring in late-exponential-early-stationary growth phase. The enzyme was cell bound and associated with the outer membrane. Fractionation of P. gingivalis W50 localized the putative hemolysin almost exclusively in the outer membrane fraction, with significant hemolytic activity concentrated in the outer membrane vesicles. Ca2+ and Mg2+ ions significantly increased the expression of hemolytic activity. Hemolytic activity was inhibited by proteinase K, trypsin, the proteinase inhibitors Na-P-tosyl-L-lysine chloromethyl ketone and benzamidine, the metabolic inhibitor M-chlorophenyl-hydrazone, and iodoacetate. KCN and sodium azide (NaN3) only partially inhibited P. gingivalis hemolytic activity, while antiserum to whole cells of each of the P. gingivalis strains had a significant inhibitory effect on hemolytic activity. The P. gingivalis W50 hemolysin was inhibited by cysteine, dithiothreitol, and glutathione at concentrations of at least 10 mM; at low concentrations (i.e., 2 mM), dithiothreitol did not completely inhibit hemolytic activity. Heating to temperatures above 55 degrees C resulted in an almost complete inhibition of hemolytic activity. The effect of heme limitation (i.e., iron) on hemolysin production indicated that either limitation or starvation for heme resulted in significantly increased hemolysin production compared with that of P. gingivalis grown in the presence of excess heme.

Alginate synthesis by Pseudomonas aeruginosa: a key pathogenic factor in chronic pulmonary infections of cystic fibrosis patients

Pulmonary infection by mucoid, alginate-producing Pseudomonas aeruginosa is the leading cause of mortality among patients suffering from cystic fibrosis. Alginate-producing P. aeruginosa is uniquely associated with the environment of the cystic fibrosis-affected lung, where alginate is believed to increase resistance to both the host immune system and antibiotic therapy. Recent evidence indicates that P. aeruginosa is most resistant to antibiotics when the infecting cells are present as a biofilm, as they appear to be in the lungs of cystic fibrosis patients. Inhibition of the protective alginate barrier with nontoxic compounds targeted against alginate biosynthetic and regulatory proteins may prove useful in eradicating P. aeruginosa from this environment. Our research has dealt with elucidating the biosynthetic pathway and regulatory mechanism(s) responsible for alginate synthesis by P. aeruginosa. This review summarizes reports on the role of alginate in cystic fibrosis-associated pulmonary infections caused by P. aeruginosa and provides details about the biosynthesis and regulation of this exopolysaccharide.

Antisera specific for rap 1 proteins distinguish between processed and nonprocessed rap 1b

Polyclonal antisera were generated against synthetic peptides corresponding to distinct regions of the rap 1 protein sequences. A "rap 1-common" antiserum, prepared against an 18-amino acid segment of the rap 1a protein near the proposed GTP-binding region, reacted with both rap 1a and rap 1b recombinant proteins expressed in Escherichia coli and with two low molecular weight GTP-binding proteins of 22 and 24 kDa in unstimulated human platelets. An antiserum raised against a carboxyl-terminal peptide of rap 1b containing the putative site of post-translational processing reacted strongly with bacterial-expressed recombinant rap 1b and with a 24-kDa GTP-binding protein in platelets, but not with recombinant rap 1a or a 22-kDa GTP-binding protein. The mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of this rap 1b immunoreactive protein coincided with that of bacterial-expressed rap 1b and not with the faster migrating form of rap 1b that incorporates radioactivity from [3H]mevalonic acid in the insect/baculovirus system. This suggests that our rap 1b-specific antiserum recognizes only one form of rap 1b, that which has not undergone carboxyl-terminal post-translational processing.

Reduced neurotoxicity in transgenic mice overexpressing human copper-zinc-superoxide dismutase

The role of oxygen-derived free radicals, superoxide in particular, in the pathogenesis of neuronal cell death induced by glutamate was studied using cultured cortical neurons from transgenic mice overexpressing human copper-zinc-superoxide dismutase. Primary cortical neuron cultures were developed from 15-day-old fetuses of both transgenic mice and their normal littermates. Both human copper-zinc-superoxide dismutase and host mouse copper-zinc-superoxide dismutase activities in cultured neurons were identified by native gel electrophoresis followed by nitroblue tetrazolium staining. Cultured neurons grown for 10-12 days in vitro were exposed briefly to 0.5 mM glutamate for 5 minutes, followed by biochemical and morphological examinations at 2, 4, and 24 hours. Our data have demonstrated that glutamate neurotoxicity is significantly reduced in transgenic neurons at 2 and 4 hours following exposure to glutamate, as measured by the efflux of lactate dehydrogenase, the 3-O-methyl glucose space, and by phase-contrast and bright-field trypan blue staining. These data indicate that transgenic neurons containing twofold to threefold the normal amount of copper-zinc-superoxide dismutase activity as the result of expression of the human copper-zinc-superoxide dismutase transgene are protected against glutamate neurotoxicity in vitro. Our results suggest that oxidative stress, at least in part, plays an important role in the biochemical pathways amplifying N-methyl-D-aspartate receptor-mediated neurotoxicity.

Cloning, nucleotide sequence, and expression of the chromate resistance determinant of Pseudomonas aeruginosa plasmid pUM505

The chromate resistance determinant of Pseudomonas aeruginosa plasmid pUM505 was cloned into broad-host-range vector pSUP104. The hybrid plasmid containing an 11.1-kilobase insert conferred chromate resistance and reduced uptake of chromate in P. aeruginosa PAO1. Resistance to chromate was not expressed in Escherichia coli. Contiguous 1.6- and 6.3-kilobase HindIII fragments from this plasmid hybridized to pUM505 but not to P. aeruginosa chromosomal DNA and only weakly to chromate resistance plasmids pLHB1 and pMG6. Further subcloning produced a plasmid with an insert of 2,145 base pairs, which was sequenced. Analysis of deletions revealed that a single open reading frame was sufficient to determine chromate resistance. This open reading frame encodes a highly hydrophobic polypeptide, ChrA, of 416 amino acid residues that appeared to be expressed in E. coli under control of the T7 promoter. No significant homology was found between ChrA and proteins in the amino acid sequence libraries, but 29% amino acid identity was found with the ChrA amino acid sequence for another chromate resistance determinant sequenced in this laboratory from an Alcaligenes eutrophus plasmid (A. Nies, D. Nies, and S. Silver, submitted for publication).

Effects of MK-801 on glutamate-induced swelling of astrocytes in primary cell culture

The effects of glutamate and its agonists and antagonists on the swelling of primary astrocytes were studied. Glutamate (Glu), aspartate (Asp), homocysteate (HCA), and quisqualate (Quis) at 1 mM concentration caused a significant increase in astrocytic swelling as measured by the 3-0-methyl-[14C]-glucose, whereas kainate (KA), N-methyl-D-aspartate (NMDA), and receptor antagonists 2-amino-5-phosphonovaleric acid (APV), 2-amino-7-phosphonohepatanoic acid (APH), and kynurenic acid (Kynu) were not effective. This glial swelling was time-dependent since 1-hr or greater incubations with Glu or its agonists were needed to produce such an effect. Preincubation of glutamate or NMDA receptor anatogonists including Kynu, APH, and APV failed to ameliorate the Glu effects. However, MK-801, a noncompetitive NMDA antagonist, when added to the Glu-incubated astrocytes significantly reduced Glu-induced astrocytic swelling. MK-801 was also effective in reducing the astrocytic swelling induced by agonists including Asp, Quis, and HCA, suggesting that those agonists may share similar mechanisms of Glu in inducing astrocytic swelling. Since the cultured astrocytes lack the NMDA receptors, our data suggest that the observed beneficial effects of MK-801 on excitotoxin-induced swelling of astrocytes may be mediated by mechanisms other than NMDA receptors.

Attenuation of glutamate-induced neuronal swelling and toxicity in transgenic mice overexpressing human CuZn-superoxide dismutase

The role of oxygen-derived free radicals, superoxide in particular, in the pathogenesis of neuronal cell death induced by glutamate was studied using primary culture cortical neurons from transgenic mice overexpressing human CuZn-superoxide dismutase. Primary cortical neuron cultures were developed form 15-day-old fetuses of both transgenic mice and their normal littermates. Both human CuZn-superoxide dismutase and host mouse CuZn-superoxide dismutase activities in cultured neurons were identified by native gel electrophoresis followed by nitroblue tetrazolium staining. Cultured neurons grown for 10-12 days in vitro were exposed briefly to 0.5 mM glutamate for 5 minutes, followed by biochemical and morphological examinations at 2 and 4 hours. Our data have demonstrated that glutamate neurotoxicity is significantly reduced in transgenic neurons at 2 and 4 hours following exposure to glutamate, as measured by the intracellular 3-0-methyl glucose space, the efflux of lactate dehydrogenase, and by phase-contrast and bright-field trypan blue staining. These data indicate that transgenic neurons containing two- to threefold the normal amount of CuZn-superoxide dismutase activity are protected against glutamate neurotoxicity in vitro. Our results suggest that oxidative stress play an important role in glutamate-induced neuronal swelling and toxicity.

Nucleotide sequence of a regulatory region controlling alginate synthesis in Pseudomonas aeruginosa: characterization of the algR2 gene

Alginate (Alg), an exopolysaccharide with strong gelling properties, is produced by Pseudomonas aeruginosa primarily during its infection of the cystic fibrosis (CF) lung. The alg genes are normally not expressed in other environments. The promoter for a critical Alg biosynthetic gene, algD, encoding GDP-mannose dehydrogenase, is activated only under conditions reminiscent of the CF lung (i.e., under high osmolarity), and at least two regulatory genes, algR1 and algR2, have been implicated in this activation process. The physical mapping of a 4.4-kb region harboring algR2 has been accomplished and the complete nucleotide sequence of this fragment, including that of algR2, is presented. The cloning and complementation experiments also demonstrate the presence, on this fragment, of regulatory gene(s) different from algR1 and algR2. The expression of the algR2 gene allows a high level of activation of the algD promoter in Escherichia coli, in the presence of algR1 in a high osmotic environment, suggesting that the AlgR2 and AlgR1 proteins act cooperatively to activate the algD promoter. Hyperexpression of the algR2 gene from the tac promoter also allows the conversion of nonmucoid cells of strain 8822, a spontaneous revertant of the mucoid CF isolate strain 8821, back to mucoidy, but not that of the clinical isolate, strain PAO1.

Expression and nucleotide sequence of a plasmid-determined divalent cation efflux system from Alcaligenes eutrophus

Resistance to cobalt, zinc, and cadmium specified by the czc determinant on plasmid pMOL30 in Alcaligenes eutrophus results from a cation efflux system. Five membrane-bound polypeptides that were expressed in Escherichia coli from this determinant under the control of a phage T7 promoter were assigned to four open reading frames identified in the nucleotide sequence of the 6881-base-pair fragment containing the czc putative operon. The contributions of the polypeptides to the cation efflux system were analyzed with deletion derivatives of the 6.9-kilobase fragment, constructed, and expressed in E. coli under the control of the phage T7 promoter and in A. eutrophus under the control of the lac promoter.

Mercury operon regulation by the merR gene of the organomercurial resistance system of plasmid pDU1358

The structural basis for induction of the mercury resistance operon with inorganic mercury and with the organomercurial compound phenylmercuric acetate was addressed by DNA sequencing analysis and by lac fusion transcription experiments regulated by merR in trans from broad-spectrum-resistance plasmid pDU1358 (Hg2+ and phenylmercury responding). The lac fusion results were compared with those from a narrow-spectrum-resistance (Hg2+ responding but not phenylmercuric responding) operon and the pDU1358 merR deleted at the 3' end. The nucleotide sequence of the beginning region of the broad-spectrum mer operon of plasmid pDU1358 was determined, including that of the merR gene, the operator-promoter region, the merT and merP genes, and the first 60% of the merA gene. Comparison of this sequence with DNA sequences of narrow-spectrum mer operons from transposon Tn501 and plasmid R100 showed that a major difference occurred in the 3' 29 base pairs of the merR gene, resulting in unrelated C-terminal 10 amino acids. A hybrid mer operon consisting of the merR gene from pDU1358, a hybrid merA gene (determining mercuric reductase enzyme), and lacking the merB gene (determining phenylmercury lyase activity) was inducible by both phenylmercury and inorganic Hg2+. This shows that organomercurial lyase is not needed for induction by organomercurial compounds. A mutant form of pDU1358 merR missing the C-terminal 17 amino acids responded to inorganic Hg2+ but not to phenylmercury. Thus, the C-terminal region of the MerR protein of the pDU1358 mer operon is involved in the recognition of phenylmercury.

Ketamine protects cultured astrocytes from glutamate-induced swelling

Effects of ketamine on glutamate-induced swelling of astrocytes in primary cell culture were studied. Following the exposure to 1 mM glutamate (Glu) for 4 h the intracellular water space (as measured by 3-O-methyl-[14C]glucose uptake) of astrocytes was increased by two-fold concomitant with cell swelling and disappearance of cellular processes observed by phase-contrast microscopy. Ketamine, when co-incubated with Glu, reduced the astrocytic swelling in a dose-dependent manner. These data suggested that ketamine, in addition to its function as a non-competitive N-methyl-D-aspartate receptor antagonist, is also involved in protecting astrocytes from Glu-induced swelling.

Cadmium resistance from Staphylococcus aureus plasmid pI258 cadA gene results from a cadmium-efflux ATPase

Cadmium resistance specified by the cadA determinant of Staphylococcus aureus plasmid pI258 results from the functioning of a cadmium-efflux system. In the nucleotide sequence of the DNA fragment containing the cadA determinant, two open reading frames were identified. The larger one, corresponding to a predicted polypeptide of 727 amino acid residues, is necessary and sufficient for expression of cadmium resistance. Comparison of the CadA amino acid sequence with known protein sequences suggested that CadA is a member of the E1E2 cation-translocating ATPases, similar to the K+-uptake ATPases of Gram-positive and Gram-negative bacteria. The sequence homology is lower but significant with other E1E2-type ATPases, including the H+-efflux ATPases of eukaryotic microbes and the Ca2+- and Na+/K+-ATPases of animals. A frame-shift mutation in the middle of the gene destroys the Cd2+-resistance phenotype. A detailed model for the putative CadA ATPase based on homologies to other E1E2 ATPases is presented and discussed.

Bacterial resistance ATPases: primary pumps for exporting toxic cations and anions

Bacterial plasmid resistance systems that maintain low intracellular levels of toxic heavy metals by pumping the substrates out as rapidly as they accumulate sometimes work at the biochemical level as efflux ATPases. The two systems responsible for arsenic and cadmium resistance have recently been sequenced. Comparison of the deduced amino acid sequences with those of better characterized ATPases has revealed certain structural and sequence similarities.

Reduction of activities of superoxide dismutase but not of glutathione peroxidase in rat brain regions following decapitation ischemia

Effects of complete ischemia on levels of antioxidative enzymes including copper-zinc (CuZn) superoxide dismutase (SOD), manganese (Mn)-SOD, and glutathione peroxidase (GSH-Px) were studied in rat brain regions at 30 and 60 min following decapitation. CuZn-SOD activities were significantly decreased in cerebral cortex and hippocampus at both time points whereas the enzyme activities were decreased at 60 min in cerebellum and caudate areas. The reduction of Mn-SOD activities followed the same pattern of CuZn-SOD in various brain regions. However, GSH-Px activities in these brain regions were not affected by decapitation ischemia. These data suggest that the reduction of CuZn-SOD and Mn-SOD activities during ischemia, in conjunction with the significant decrease in the contents of alpha-tocopherol and other endogenous antioxidants, may compromise the brain's ability to defend against the toxic effects of superoxide radicals formed by ischemia and by subsequent reoxygenation.