Effects of Celebrex and Zyflo on BOP-induced pancreatic cancer in Syrian hamsters

BACKGROUND/AIMS

Selective inhibition of eicosanoid synthesis decreases inflammation, however, it is still unknown whether oxidative stress and carcinogenesis might be influenced in ductal pancreatic ductal cancer as well.

METHODS

120 male hamsters were randomized into 8 groups (n = 15). While control group 1-4 received 0.5 ml normal saline s.c. weekly for 16 weeks, groups 5-8 were injected 10 mg BOP/kg body weight to induce pancreatic cancer. After establishment of pancreatic cancer, groups 1 and 5 received no therapy, groups 2 and 6 were fed 7 mg Celebrex daily, groups 3 and 7 were given 28 mg Zyflo and groups 4 and 8 received Celebrex and Zyflo orally daily in weeks 17-32. In week 33, all animals were sacrificed, macroscopic size of pancreatic carcinomas was measured, incidence of pancreatic cancer was analyzed histopathologically and activities of antioxidative enzymes and concentration of products of lipid peroxidation in tumor-free and pancreatic intratumoral tissue were determined.

RESULTS

Incidence and size of macroscopic pancreatic carcinomas were decreased by single therapy with Zyflo as well as combined therapy (Zyflo + Celebrex). Activities of antioxidative enzymes were increased and the concentration of products of lipid peroxidation was decreased in tumor-free pancreas. On the other hand, lipid peroxidation was increased in pancreatic tumors.

CONCLUSION

Zyflo alone or in combination with Celebrex reduce tumor growth in pancreatic cancer and thus might be a new therapeutic option in advanced pancreatic cancer.

Amino acid sequence requirements in the human IgA1 hinge for cleavage by streptococcal IgA1 proteases

All the IgA1 proteases of the different pathogenic species of Streptococcus cleave the hinge of the alpha chain of human IgA1 only at one proline-threonine peptide bond. In order to study the importance of these amino acids for cleavage, several hinge mutant recombinant IgA1 antibodies were constructed. The mutations were found to be without major effect upon the structure or functional abilities of the antibodies. However, they had a major effect upon their sensitivity to cleavage by some of the IgA1 proteases.

Effects of taurolidine and octreotide on port site and liver metastasis after laparoscopy in an animal model of pancreatic cancer

Port site metastasis is a dreadful event following laparoscopy; however, the exact pathomechanism is still unknown. In order to prevent trocar metastasis we determined the effects of intraperitoneal lavage with either taurolidine or octreotide on port site and liver metastasis after laparoscopy in a chemically induced, solid pancreatic adenocarcinoma. Pancreatic adenocarcinoma was induced in 60 Syrian hamsters by weekly injection of 10 mg/kg body weight N-nitrosobis-2-oxopropylamine s.c. for 10 weeks. Six weeks later, a laparoscopic pancreatic biopsy was performed by the use of a pneumoperitoneum with carbon dioxide (12 mm Hg), followed by an abdominal irrigation with 5 ml normal saline (group 1, n = 20), 5 ml 0.5% taurolidine (group 2, n = 20) or 5 ml octreotide (20 mg/ml) (group 3, n = 20). After 8 weeks, all hamsters were sacrificed and histopathologically examined. There was only one macroscopic visible primary tumor in the taurolidine group (5.9%), compared to 42.1% in the saline group and 62.5% in the octreotide group (P < 0.05). The size of carcinomas was smaller in the saline group than after octreotide irrigation (median 6, range 2-25 vs. median 70, range 40-160 mm2, P < 0.05). The number of liver metastases per animal was increased after saline irrigation (median 4, range 2-6), compared to taurolidine (median 2, range 1-3) or octreotide (median 2.5, range 2-4) (P < 0.05). Port site metastases were found in 36.8% after saline, in 37.5% after octreotide and in 0% after taurolidine irrigation (P < 0.05). Thus port site metastasis was effectively prevented by taurolidine irrigation after staging-laparoscopy in pancreatic cancer.

Intensified microbiological investigations in adult patients admitted to hospital with lower respiratory tract infections

The objective of this study was to investigate the diagnostic yield of a programme with intensified microbiological investigations in immunocompetent adult patients with lower respiratory tract infections (LRTI). Patients in the study group were included prospectively and consecutively from September 1st 1997 to May 31st 1998 and were compared with a control group from the preceding year. A total of 67 adult patients were included in the study group and they were compared with 122 adult patients in the control group. The study group underwent fibre-optic bronchoscopy (FOB) with bronchoalveolar lavage (BAL). Only 7% in the historic control group were discharged with an aetiological diagnosis of their infections; while the diagnostic yield in the study group increased to 51% of patients. In the study group the presence of new infiltrates on chest X-ray increased the detection of a microbiological aetiology from 37% with no infiltrates to 62% with infiltrates and recent antibiotic therapy reduced the detection of a microbiological cause of infection from 61% in 36 patients who had not received antibiotic therapy to 39% in 31 patients who had received recent antibiotic therapy prior to microbiological sampling. Patients in the study group with known aetiology had higher values of inflammatory markers than patients with unknown aetiology. For Streptococcus pneumoniae infection culture and urine antigen detection were complimentary depending on recent antibiotic therapy since seven of eight culture-positive patients had not received antibiotic therapy within 72 h prior to investigation, while all four patients positive for urine antigens from S. pneumoniae had received antibiotic therapy within 72 h of urine sampling. In conclusion intensified microbiologic investigations increase the diagnostic yield from 7% to 51% of patients in the study group with an aetiologic diagnosis. Routine FOB with BAL had no apparent effect on clinical outcome and seems only justified in selected patients with severe LRTI with infiltrates on chest X-ray and signs of severe inflammation where a high diagnostic yield is achieved.

Quantitative culture of bronchoalveolar lavage fluid in community-acquired lower respiratory tract infections

To evaluate the diagnostic value of quantitative bacterial culture of bronchoalveolar lavage (BAL) fluid obtained by fibreoptic bronchoscopy, 67 consecutive immunocompetent adult patients admitted to hospital with community-acquired lower respiratory tract infections from September 1997 to May 1998 were investigated. Results were compared to the findings in eight healthy control persons investigated in February 1998. There was no difference between study patients and control persons when quantitative culture of total cumulative bacterial findings or bacteria categorized as members of the oropharyngeal normal flora were compared. The culture of normal flora in bronchial washings probably reflects contamination of the lower airways with secretions from upper arways by the fibreoptic procedure itself, as fractionated sampling showed a 10-fold reduct on in quantitative culture results when a primary bronchial washing was compared to a secondary sampling from the same bronchus in the control group. Twenty-four (36%) of 67 patients were cultured as positive in the study group while all control persons were cultured as negative for bacteria categorized as potential pathogens. With a threshold value for positive culture of 10(4) cfu ml(-1) the specificity of lavage culture of potential pathogenic bacteria in relation to actual lower airway infection was 100%. Therefore, quantitative bacterial culture of potential pathogenic bacteria in BAL fluid is very specific but only positive in about one-third of unselected immunocompetent adult patients with a lower respiratory tract infection.

Retrieval of biofilms from the oral cavity

With the use of the removable stents or bonded enamel piece models with or without a continuous bacterial layer, many in vitro or in vivo studies can be initiated. For example, studies on salivary pellicle formation, surface characteristics of biomaterials as they affect plaque development, antiplaque agents, the dynamics of adhesion of bacteria, interspecies adhesion of bacteria, the colonization of bacteria, the dynamics of bacterial growth in vivo, and the succession of growth in older supragingival plaques can be carried out.

Influence of octreotide on liver metastasis and hepatic lipid peroxidation in BOP-induced pancreatic cancer in Syrian hamsters

INTRODUCTION

In prospective clinical trials, octreotide improved quality of life and survival time in patients with pancreatic cancer.

AIMS

To analyze whether octreotide modulates the hepatic oxygen radical metabolism and thus might decrease liver metastasis in an animal model of pancreatic cancer.

METHODOLOGY

Syrian hamsters received 0.9% NaCl or N-nitrosobis(2-oxopropyl)amine (BOP) for 3 months. Therapy was performed for 12 weeks by 0.9% NaCl or octreotide. Hamsters received a standard diet (3.5% fat) or were fed a high-fat diet (21.4% fat). In the 25th week, the pancreas and liver were examined macroscopically and histologically. The level of lipid peroxidation and activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) were determined intrahepatically.

RESULTS

The number of liver metastases per animal and the size of liver metastases were increased by the high-fat diet, whereas they were decreased by octreotide. Octreotide increased activities of GSH-Px and SOD. The concentration of thiobarbituric acid reactive substances was increased by BOP and a high-fat diet and decreased by octreotide.

CONCLUSION

Octreotide decreases the number and size of liver metastases in chemically induced pancreatic cancer in Syrian hamsters. This is accompanied by high hepatic GSH-Px and SOD activity and a low level of lipid peroxidation.

Population dynamics of Streptococcus mitis in its natural habitat

The purpose of this study was to examine the genetic structure of the typical commensal Streptococcus mitis biovar 1 in its natural habitat in the human oral cavity and pharynx and to investigate the role that selected microbial properties and host, spatial, and temporal factors play in determining the structure of the bacterial population. Consecutive samples were collected from buccal and pharyngeal mucosal surfaces of two infants, their four parents, and two elderly individuals over a period of approximately 1 year. A total of 751 isolates identified as S. mitis biovar 1 were typed by restriction endonuclease analysis (REA) and representative clones were typed by multilocus enzyme electrophoresis (MLEE). The genetic diversity of the S. mitis biovar 1 isolates collected from single infant hosts over a period of 9 to 10 months was found to be between 0.69 and 0.76, which is considerably higher than that previously observed for intestinal populations of Escherichia coli. The study provides evidence of the existence of both transient and persistent clones in adult individuals. In the two infants, however, none of 42 demonstrated clones were detected on more than a single occasion. Statistical calculations showed that the ability to persist was not distributed at random in the S. mitis biovar 1 population. However, neither immunoglobulin A1 protease activity nor the ability to bind alpha-amylase from saliva was a preferential characteristic of persistent genotypes. In contrast to current concepts of climax ecosystems, the species niche in the habitat appears to be maintained predominantly by a succession of clones rather than by stable strains. Several lines of evidence suggest that the major origin of "new" clones is the many other habitats in the respiratory tract that are occupied by this species.

The impact of laparoscopic biopsy of pancreatic lymph nodes on lipid peroxidation using helium and carbon dioxide in BOP-induced pancreatic cancer in hamsters

BACKGROUND

Increased lipid peroxidation is believed to stimulate liver metastasis in pancreatic cancer. However, the effect of the laparoscopic biopsy of pancreatic lymph nodes on liver metastasis is still unknown. We hypothesized that the effects of a pneumoperitoneum with carbon dioxide (CO2) increase lipid peroxidation and stimulate liver metastasis.

METHODS

Ductal pancreatic adenocarcinoma was induced in Syrian hamsters (n = 30) by weekly subcutaneous injections of N-nitrosobis-2-oxopropylamine (BOP) for 12 weeks. In group 1, a laparotomy and biopsy of pancreatic lymph nodes was performed. Groups 2 and 3 underwent laparoscopic biopsy with either CO2 or helium. In the 5th postoperative week, the hamsters were killed and the incidence of liver metastasis was analyzed histopathologically. We then made determinations of the level of lipid peroxidation (thiobarbituric acid-reactive substances [TBARS])as well as the activity of glutathionperoxidase (GSH-PX) and superoxidismutase (SOD) in pancreatic carcinoma and liver metastases of the animals.

RESULTS

The incidence of liver metastasis was higher in the CO2 group (60%) than in the helium (30%) and laparotomy groups (20%) (p < 0.05). The concentration of TBARS was greater in pancreatic carcinoma and intrametastatic hepatic tissue than in extratumorous pancreatic and extrametastastic hepatic tissue in all groups. Extrametastatic hepatic concentration of TBARS was higher in the CO2 group (19.4 +/- 0.88 nmol/mg protein) than the laparotomy (10.66 +/- 0.95 nmol/mg protein) and helium groups (10.79 +/- 0.58 nmol/mg protein). GSH-PX and SOD activity was significantly lower in pancreatic carcinoma tissue and intrametastatic hepatic tissue than in extratumorous pancreatic and extrametastatic hepatic tissue. However, in the CO2 group (1.24 +/- 0.48 107 U/mg protein), extrametastatic GSH-PX activity was lower than in the laparotomy (1.73 +/- 0.4 107 U/mg protein) and helium groups (1.63 +/- 0.28 107 U/mg protein).

CONCLUSION

After laparoscopic biopsy of pancreatic lymph nodes in the CO2 group, lipid peroxidation was increased and GSH-PX activity was decreased in extrametastatic hepatic tissue compared to the intrametastatic sections. This mechanism may be responsible for the increased liver metastasis in the CO2 group.

Epidemic population structure of Pseudomonas aeruginosa: evidence for a clone that is pathogenic to the eye and that has a distinct combination of virulence factors

The genetic structure of a population of Pseudomonas aeruginosa, isolated from patients with keratitis, endophthalmitis, and contact lens-associated red eye, contact lens storage cases, urine, ear, blood, lungs, wounds, feces, and the environment was determined by multilocus enzyme electrophoresis. The presence and characteristics of virulence factors were determined by restriction fragment length polymorphism analysis with DNA probes for lasA, lasB, aprA, exoS, exoT, exoU, and ctx and by zymography of staphylolysin, elastase, and alkaline protease. These analyses revealed an epidemic population structure of P. aeruginosa, characterized by frequent recombination in which a particular successful clone may increase, predominate for a time, and then disappear as a result of recombination. Epidemic clones were found among isolates from patients with keratitis. They were characterized by high activity of a hitherto-unrecognized size variant of elastase, high alkaline protease activity, and possession of the exoU gene encoding the cytotoxic exoenzyme U. These virulence determinants are not exclusive traits in strains causing keratitis, as strains with other properties may cause keratitis in the presence of predisposing conditions. There were no uniform patterns of characteristics of isolates from other types of infection; however, all strains from urinary tract infections possessed the exoS gene, all strains from environment and feces and the major part of keratitis and wound isolates exhibited high elastase and alkaline protease activity, and all strains from feces showed high staphylolysin activity, indicating that these virulence factors may be important in the pathogenesis of these infectious diseases.

Influence of antioxidative vitamins A, C and E on lipid peroxidation in BOP-induced pancreatic cancer in Syrian hamsters

Persistent oxidative stress is thought to play an important role in carcinogenesis. Vitamins may influence oxygen radical metabolism and thus inhibit tumor growth. In the present trial the effects of Vitamins (Vit.) A, C and E on neoplastic growth and lipid peroxidation in pancreatic tissue were evaluated on chemically-induced pancreatic adenocarcinoma in the Syrian hamster. The incidence of pancreatic cancer was decreased by Vit. A (64.3%) and Vit. C (71.4%) as compared to the control group (100%, P<0.05). All vitamins increased the activity of superoxidedismutase (SOD) in pancreatic carcinomas. Accumulation of vitamins in tumor cells seems to be responsible for high levels of SOD and consecutive intracellular increase of hydrogen peroxide levels. Since this effect is selectively toxic for tumor cells it might be one of the mechanisms decreasing the incidence of pancreatic cancer in our trial.

Evidence of recombination in Porphyromonas gingivalis and random distribution of putative virulence markers

The association of Porphyromonas gingivalis to periodontal disease is not clearly understood. Similar proportions of P. gingivalis may be cultivated from both inactive and actively degrading periodontal pockets. Differences in virulence among strains of P. gingivalis exist, but the molecular reason for this remains unknown. We examined the population structure of P. gingivalis to obtain a framework in which to study pathogenicity in relation to evolution. Phylogenetic trees derived from the sequencing of fragments of four housekeeping genes, ahp, thy, rmlB, and infB, in 57 strains were completely different with no correlation between clustering of strains in the four dendrograms. Combining the various alleles of the four gene fragments sequenced resulted in 41 different sequence types. The index of association, I(A), based on a single representative of each sequence type was 0.143 +/- 0.202, indicating a population at linkage equilibrium. Inclusion of all isolates for the calculation of I(A) resulted in a value of 0.206 +/- 0.171. This suggests an epidemic population structure supported by the finding of genetically identical strains in different parts of the world. We observed a random distribution of two virulence-associated mobile genetic elements, the ragB locus and the insertion sequence IS1598, among 132 strains tested. In conclusion, P. gingivalis has a nonclonal population structure characterized by frequent recombination. Our study suggests that particular genotypes, possibly with increased pathogenic potential, may spread successfully in the human population.

Influence of octreotide and tamoxifen on tumor growth and liver metastasis in N-nitrosobis(2-oxopropyl)amine-induced pancreatic cancer in Syrian hamsters

In prospective clinical trials single octreotide therapy or combined therapy with tamoxifen has improved the quality of life and survival time in patients with pancreatic cancer. In this study we analyzed the influence of octreotide and tamoxifen on tumor growth and liver metastases in chemically induced pancreatic adenocarcinoma in Syrian hamsters. Octreotide alone and the combined therapy (octreotide/tamoxifen) decreased the incidence of macroscopic pancreatic carcinomas as well as the number and size of liver metastases. The combined therapy showed no superior effect to octreotide alone. Furthermore, there was no difference between the tamoxifen and the control group.

Early-onset periodontitis in Morocco is associated with the highly leukotoxic clone of Actinobacillus actinomycetemcomitans

A particular clone (JP2) of Actinobacillus actinomycetemcomitans with increased leukotoxin production has been isolated from individuals with early-onset periodontitis (EOP). The aim of this study was to determine the frequency of carriers of this clone and its association with EOP in Moroccan schoolchildren. Of 217 plaque samples, 131 (60.4%) were culture-positive for A. actinomycetemcomitans. A total of 19 of these isolates had a 530-bp deletion in the leukotoxin promoter region characteristic of the JP2 clone. A strong association between the presence of A. actinomycetemcomitans with the 530-bp deletion and EOP was found (adjusted OR = 29.4; 95% Cl = 8.3 - 104.4; p < 0.0005), while no association could be demonstrated between the presence of A. actinomycetemcomitans without the deletion and EOP (adjusted OR = 1.3; 95% CI = 0.5 -2.9; p = 0.750). The study demonstrates that the endemic presence, in a human population, of the highly leukotoxic JP2 clone may result in an unusually high prevalence of EOP.

Effects of octreotide on liver metastasis and intrametastatic lipid peroxidation in experimental pancreatic cancer

OBJECTIVES

In prospective clinical trials, octreotide improved the quality of life and survival time in patients with pancreatic cancer. In this study, we analyzed whether octreotide modulates the intrametastatic oxygen radical metabolism and might decrease liver metastasis in a model of pancreatic cancer.

METHODS

Syrian hamsters received 0.9% NaCl or N-nitrosobis(2-oxopropyl)amine for 3 months. Therapy was performed for 12 weeks by 0.9% NaCl or octreotide. Hamsters received a standard diet or were fed a high-fat diet. In the 25th week, pancreas and liver were examined macroscopically and histologically. The level of lipid peroxidation and the activity of glutathione peroxidase and superoxide dismutase were determined intrahepatically and intrametastatically.

RESULTS

The number and size of liver metastases per animal were increased by high-fat diet and decreased by octreotide. While high-fat diet increased intrahepatic extrametastatic lipid peroxidation, octreotide decreased intrahepatic extrametastatic lipid peroxidation and increased intrametastatic lipid peroxidation.

CONCLUSIONS

Octreotide decreases the number and size of liver metastases in chemically induced pancreatic cancer in Syrian hamsters. Possible mechanisms are the prevention of high lipid peroxidation in non-metastatic liver as well as the increase in intrametastatic lipid peroxidation, leading to loss of integrity of spread tumor cells.

The impact of laparoscopic biopsy of pancreatic lymph nodes with helium and carbon dioxide on port site and liver metastasis in BOP-induced pancreatic cancer in hamster

The influence of pancreatic biopsy during laparoscopy with carbon dioxide (CO2) and helium on the incidence of port site and liver metastasis in pancreatic carcinoma is still unknown. Ductal adenocarcinoma of the pancreas was induced in Syrian hamsters (n = 30) by injection of N-nitrosobis-2-oxopropylamin (BOP, 10 mg/kg body weight/week) for 12 weeks. In week 13, hamsters were randomized in 3 groups (n = 10): While in group 1 (gr. 1) a laparotomy and biopsy of pancreatic lymph nodes was performed, gr. 2 and gr. 3 underwent a laparoscopic biopsy either with CO2 or helium. Therefore, one trocar was located in the left (biopsy) and the right abdominal wall (camera). In the 18th week all animals were sacrificed and the incidence of abdominal wall, port site and liver metastases was histologically determined. While there were abdominal wall metastases after laparotomy in 10% (n = 1), we observed trocar metastases in the CO2 group in 20% (n = 2). However, there were no trocar metastases in the helium group. The incidence of liver metastasis did not differ between the laparotomy and the helium group (20% vs 30%), but was increased in the CO2 group (60%). Laparoscopic biopsy of pancreatic lymph nodes with CO2 increased the incidence of port site and liver metastases in pancreatic cancer. The helium group was equal to the laparotomy group in this respect. Thus, staging laparoscopy with helium might become an alternative to explorative laparotomy in pancreatic cancer.

Recommended conservation of the names Streptococcus sanguis, Streptococcus rattus, Streptococcus cricetus, and seven other names included in the Approved Lists of Bacterial Names. Request for an opinion

With reference to the first Principle of the International Code of Nomenclature of Bacteria, which emphasizes stability of names, it is proposed that the original names Streptococcus sanguis, Streptococcus rattus, Streptococcus cricetus, Erwinia ananas, Eubacterium tarantellus, Lactobacillus sake, Nitrosococcus oceanus, Pseudomonas betle, Rickettsia canada and Streptomyces rangoon, all included in the Approved Lists of Bacterial Names, be conserved. Request for an Opinion.

Heterogeneity of O-glycosylation in the hinge region of human IgA1

Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry was applied to studies of the molecular heterogeneity of desialylated human IgA1 hinge region glycopeptides released with two IgA1 proteases. Typically, the hinge region of an alpha1 chain contains three to five O-linked glycan chains. Variants of the hinge region peptides released from IgA1(Kni) myeloma protein carrying 0, 1, 2, or 3 GalNAc residues were observed in the mass spectra as well as the nonglycosylated peptide. Variable numbers of Gal residues indicated additional heterogeneity in O-glycosylation of IgA1. In the hinge region preparation from normal human serum IgA1, glycopeptides carrying 2, 3, 4, or 5 GalNAc residues with variable numbers of Gal residues were detected. In conclusion, our new approach using the site-specific cleavage with two IgA1 proteases allowed precise and sensitive MALDI-TOF mass spectrometric analysis of O-glycosylation heterogeneity in IgA1 hinge region.

Structures of two cell wall-associated polysaccharides of a Streptococcus mitis biovar 1 strain. A unique teichoic acid-like polysaccharide and the group O antigen which is a C-polysaccharide in common with pneumococci

The cell wall of Streptococcus mitis biovar 1 strain SK137 contains the C-polysaccharide known as the common antigen of a closely related species Streptococcus pneumoniae, and a teichoic acid-like polysaccharide with a unique structure. The two polysaccharides are different entities and could be partially separated by gel chromatography. The structures of the two polysaccharides were determined by chemical methods and by NMR spectroscopy. The teichoic acid-like polymer has a heptasaccharide phosphate repeating unit with the following structure: The structure neither contains ribitol nor glycerol phosphate as classical teichoic acids do, thus we have used the expression teichoic acid-like for this polysaccharide. The following structure of the C-polysaccharide repeating unit was established: where AAT is 2-acetamido-4-amino-2,4, 6-trideoxy-D-galactose. It has a carbohydrate backbone identical to that of one of the two structures of C-polysaccharide previously identified in S. pneumoniae. C-polysaccharide of S. mitis is characterized by the presence, in each repeating unit, of two residues of phosphocholine and both galactosamine residues in the N-acetylated form. Immunochemical analysis showed that C-polysaccharide constitutes the Lancefield group O antigen. Studies using mAbs directed against the backbone and against the phosphocholine moiety of the C-polysaccharide revealed several different patterns of these epitopes among 95 S. mitis and Streptococcus oralis strains tested and the exclusive presence of the group O antigen in the majority of S. mitis biovar 1 strains.

Strain-related acid production by oral streptococci

Acid production, in particular at low pH, is thought to be an important ecological determinant in dental caries. The aim of the present study was to determine the acid producing capability at different pH levels of 47 streptococcal strains, representing 9 species, isolated from human dental plaque. The bacteria were grown until mid log-phase under anaerobic conditions and acid production was measured in a pH-stat system at pH 7.0, 6.0, 5.5 and 5.0. At all pH values, the mean velocity of acid production (V(ap)) by Streptococcus mutans and S. sobrinus was significantly higher (p<0.01; ANOVA) than that of the other oral streptococci, including S. mitis, S. oralis, S. gordonii, S. sanguis, S. intermedius, S. anginosus, S. constellatus, and S. vestibularis. However, the V(ap) of some strains of S. mitis biovar 1 and S. oralis, particularly at pH values of 7.0 and 6.0, exceeded that of some strains of S. mutans. The V(ap) decreased with pH for all strains, but some strains of S. mitis biovar 1 and strains of the mutans streptococci maintained a relatively high rate of acid production. The results suggest that some strains of S. mitis biovar 1 and S. oralis may play an important role in caries development by modifying the environment in dental plaque to become favourable for the succession of aciduric species. The study furthermore emphasises the need for detailed species and biovar identification of oral streptococci and for recognition of the significant physiological differences that occur within single species.

Resident aerobic microbiota of the adult human nasal cavity

Recent evidence strongly suggests that the microbiota of the nasal cavity plays a crucial role in determining the reaction patterns of the mucosal and systemic immune system. However, little is known about the normal microbiota of the nasal cavity. The purpose of this study was to determine the microbiota in different parts of the nasal cavity and to develop and evaluate methods for this purpose. Samples were collected from 10 healthy adults by nasal washes and by swabbing of the mucosa through a sterile introduction device. Both methods gave results that were quantitatively and qualitatively reproducible, and revealed significant differences in the density of the nasal microbiota between individuals. The study revealed absence of gram-negative bacteria that are regular members of the commensal microbiota of the pharynx. Likewise, viridans type streptococci were sparsely represented. The nasal microbiota was dominated by species of the genera Corynebacterium, Aureobacterium, Rhodococcus, and Staphylococcus, including S. epidermis, S. capitis, S. hominis, S. haemolyticus, S. lugdunensis and S. warneri. These studies show that the microbiota of the nasal cavity of adults is strikingly different from that of the pharynx, and that the nasal cavity is a primary habitat for several species of diphtheroids recognized as opportunistic pathogens. Under special circumstances, single species, including IgA1 protease-producing bacteria, may become predominant in a restricted area of the nasal mucosa.

Immunoglobulin A1 protease activity in Gemella haemolysans

The purpose of this study was to determine the occurrence and nature of immunoglobulin A1 (IgA1) protease activity in members of the genus Gemella and related taxa. Among a total of 22 Gemella strains belonging to the four species Gemella haemolysans, Gemella morbillorum, Gemella sanguinis, and Gemella bergeriae and four reference strains of the species Helcococcus kunzii, Facklamia hominis, and Globicatella sanguinis, IgA1 protease activity was an exclusive character of all nine isolates of G. haemolysans. The IgA1 protease of G. haemolysans appears to be a metallo-type IgA1 protease that cleaves the Pro(227)-Thr(228) peptide bond in the hinge region of the alpha1 chain like that of several Streptococcus species. Phenotypic characterization of the isolates demonstrates that screening for IgA1 protease activity provides a valuable means for species differentiation in this group of bacteria.

Does alpha-linolenic acid in combination with linoleic acid influence liver metastasis and hepatic lipid peroxidation in BOP-induced pancreatic cancer in Syrian hamsters?

Some fatty acids are reported to inhibit tumor growth of pancreatic carcinoma. However, it is still unknown if alpha-linolenic acid (ALA) and linoleic acid (LA) inhibit liver metastasis of ductal pancreatic adenocarcinoma. Therefore we studied the effect of these fatty acids on liver metastasis in the animal model of N-nitrosobis(2-oxopropyl)amine (BOP)-induced pancreatic adenocarcinoma in Syrian hamsters. Since lipid peroxidation seems to be involved in carcinogenesis and metastasis, we further analyzed the intrahepatic concentration of thiobarbituric acid-reactive substances (TBARS) and activity of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). We observed an increase in the incidence and the number of liver metastases in response to the combination of ALA and LA. This was accompanied by a decrease in hepatic GSH-Px activity and an increase in hepatic SOD activity and TBARS concentration. The increase in hepatic lipid peroxidation seems to be one possible mechanism of increasing liver metastasis in this study.

Cleavage of a recombinant human immunoglobulin A2 (IgA2)-IgA1 hybrid antibody by certain bacterial IgA1 proteases

To understand more about the factors influencing the cleavage of immunoglobulin A1 (IgA1) by microbial IgA1 proteases, a recombinant human IgA2/IgA1 hybrid molecule was generated. In the hybrid, termed IgA2/A1 half hinge, a seven-amino-acid sequence corresponding to one half of the duplicated sequence making up the IgA1 hinge was incorporated into the equivalent site in IgA2. Insertion of the IgA1 half hinge into IgA2 did not affect antigen binding capacity or the functional activity of the hybrid molecule, as judged by its ability to bind to IgA Fcalpha receptors and trigger respiratory bursts in neutrophils. Although the IgA2/A1 hybrid contained only half of the IgA1 hinge, it was found to be cleaved by a variety of different bacterial IgA1 proteases, including representatives of those that cleave IgA1 in the different duplicated halves of the hinge, namely, those of Prevotella melaninogenica, Streptococcus pneumoniae, S. sanguis, Neisseria meningitidis types 1 and 2, N. gonorrhoeae types 1 and 2, and Haemophilus influenzae type 2. Thus, for these enzymes the recognition site for IgA1 cleavage is contained within half of the IgA1 hinge region; additional distal elements, if required, are provided by either an IgA1 or an IgA2 framework. In contrast, the IgA2/A1 hybrid appeared to be resistant to cleavage with S. oralis and some H. influenzae type 1 IgA1 proteases, suggesting these enzymes require additional determinants for efficient substrate recognition.