Streptococcus pneumoniae ClpL modulates adherence to A549 human lung cells through Rap1/Rac1 activation

Caseinolytic protease L (ClpL) is a member of the HSP100/Clp chaperone family, which is found mainly in Gram-positive bacteria. ClpL is highly expressed during infection for refolding of stress-induced denatured proteins, some of which are important for adherence. However, the role of ClpL in modulating pneumococcal virulence is poorly understood. Here, we show that ClpL impairs pneumococcal adherence to A549 lung cells by inducing and activating Rap1 and Rac1, thus increasing phosphorylation of cofilin (inactive form). Moreover, infection with a clpL mutant (ΔclpL) causes a greater degree of filopodium formation than D39 wild-type (WT) infection. Inhibition of Rap1 and Rac1 impairs filopodium formation and pneumococcal adherence. Therefore, ClpL can reduce pneumococcal adherence to A549 cells, likely via modulation of Rap1- and Rac1-mediated filopodium formation. These results demonstrate a potential role for ClpL in pneumococcal resistance to host cell adherence during infection. This study provides insight into further understanding the interactions between hosts and pathogens.

The performance of routine computed tomography for the detection of colorectal cancer

INTRODUCTION

Although colonoscopy and computed tomography (CT) colonography in expert hands are the most sensitive investigations for colorectal cancer, some patients may not tolerate the necessary bowel preparation and insufflation of gas into the colon. We assessed the performance of unprepared contrast CT for the detection of colorectal cancer.

METHODS

A retrospective review was undertaken of all patients who had contrast CT of the abdomen and pelvis and then went on to have colonoscopy at our institutions between 2007 and 2010.

RESULTS

Overall, 96 patients were identified as having had CT prior to colonoscopy. The sensitivity of CT in detecting colorectal cancer was 100% (95% confidence interval [CI]: 19.8-100%) and the specificity was 95.7% (95% CI: 88.8-98.6%). The positive predictive value was 33.3% (95% CI: 6.0-75.9%) and the negative predictive value was 100% (95% CI: 94.8-100%).

CONCLUSIONS

Non-targeted CT that is negative for colorectal malignancy is usually reassuring but the decision for further investigations should be made on a case-by-case basis, taking into account of the likelihood of underlying colorectal malignancy and the underlying co-morbidities of the patient. However, video colonoscopy is usually necessary to assess positive CT findings.

Regulation of gene expression by the NSP1 and NSP3 non-structural proteins of rotavirus

The role of the rotavirus non-structural proteins NSP1 and NSP3 in regulating cellular and viral mRNA translation has been investigated by examining the effect of added recombinant NSP3 on protein translation in a T7-based in vitro coupled transcription-translation system. Addition of purified NSP3 to assays primed solely with cellular mRNA was found to have no effect on the translation efficiency of the mRNA. However, as expected, the addition of viral mRNA to such assays competitively inhibited the synthesis of cellular protein, and interestingly, this inhibition was enhanced by the addition of NSP3. Treatment of NSP3 with antisera raised against the purified protein abrogated its function, but only when used prior to mixing the protein with viral mRNA. Addition of partially purified NSP1 to the coupled system was able to alleviate the enhancement of the inhibition of cellular mRNA translation caused by NSP3. The role of NSP1 in this process appears to be to modulate the impact of the NSP3-based inhibition of cellular translation by binding to the 5' end of viral mRNAs.

Blind subacromial injection from the anterolateral approach: the ballooning sign

PURPOSE

Our aim was to verify the association of fullness over the skin distal to anterior acromion termed "ballooning" in relation to accuracy of subacromial injection and determine its accuracy in terms of sensitivity, specificity, and predictive value. We hypothesized that a positive ballooning was a sign of an accurately placed injection into the subacromial bursa.

METHODS

Data of 136 shoulders with impingement, which received subacromial steroid injections, were evaluated for presence of ballooning signs, pain, motion, and muscle strength. Injections were performed via anterolateral approach, followed by radiographs to locate the contrast. Data were compared between pre- and post-injections as well as between accurate and inaccurate groups to evaluate the correlations between targeting accuracy and immediate outcomes.

RESULTS

Ballooning signs were positive in 104 shoulders (76.5%), of which majority were inaccurate (58.7%). The accuracy rate was 49.3% with sensitivity of 64.2%, specificity 11.6% and positive as well as negative predictive values of 41.3% and 25% consecutively. Dispersal rate to the surrounding structures was 86.6% with majority infiltrated the deltoid (29.4%). Significant improvement was noted between pre- and post-injections in all parameters except muscle strength, indicating equal pain relief regardless of locations.

CONCLUSION

The ballooning sign is not a reliable indicator for or against subacromial injection. Blind subacromial injections are frequently inaccurate using the anterolateral approach. Nevertheless, immediate improvement of pain, motion, and muscle strength can be expected regardless of location.

Cocaine increases endoplasmic reticulum stress protein expression in striatal neurons

Cocaine administration upregulates the levels of extracellular glutamate and dopamine in the striatum. Activation of the receptors alters calcium homeostasis in striatal neurons leading to the expression of the endoplasmic reticulum (ER) stress proteins. It was therefore hypothesized that cocaine upregulates the expression of the ER stress proteins, immunoglobulin heavy chain binding protein (BiP), Ire1alpha and perk via glutamate and dopamine receptor activation. A novel glutamate microbiosensor and Western immunoblot analyses were mainly performed to test the hypothesis in the rat dorsal striatum. The results showed that i.p. injection of repeated cocaine (20 mg/kg) for nine consecutive days significantly increased extracellular glutamate levels while acute cocaine injection did not. However, the immunoreactivities (IR) of the ER stress proteins in the dorsal striatum were significantly increased by either acute or repeated cocaine injections as compared with saline controls. Intrastriatal injection (i.s.) of the selective group I metabotropic glutamate receptor (mGluR) antagonist N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC; 25 nmol) or the mGluR5 subtype antagonist 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP; 2 and 25 nmol) significantly decreased repeated cocaine-induced increases in the IR of the ER stress proteins in the injected dorsal striatum. Similarly, the selective D1 antagonist (R)-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH23390; 0.1 mg/kg, i.p.) or the N-methyl-d-aspartate antagonist dizocilpine/(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-ibenzo[a,d]cyclohepten-5,10-imine maleate (MK801; 2 nmol, i.s.) decreased acute or repeated cocaine-induced the IR of the ER stress proteins in the dorsal striatum. These data suggest that cocaine upregulates expression of the ER stress proteins in striatal neurons via a mechanism involving activation of glutamate and dopamine receptors.

Horace A. Barker (1907-) pioneer of anaerobic metabolism

Dr Horace A. Barker was born and raised in California. He obtained his Ph.D. in chemistry from the University of California, Berkeley in 1933, and became a faculty member at the same campus in 1936. He devoted his research to the study of bacterial metabolism. His contributions include the detailed studies of various aspects of metabolism such as synthesis and oxidation of fatty acids, fermentation of amino acids and purines, and carbohydrate transformations. He isolated and determined the structure and function of some enzymes and coenzymes from bacteria. He also specifically described many anaerobic metabolic pathways. Dr Barker retired in 1976.

A serial comparison of arthroscopic repairs for partial- and full-thickness rotator cuff tears

PURPOSE

To compare the outcome of arthroscopic rotator cuff repair and subacromial decompression in partial-thickness rotator cuff tears (PTRCT) with those in full-thickness rotator cuff tears (FTRCT).

TYPE OF STUDY

Prospective serial follow-up study.

METHODS

Of 46 consecutive patients who were treated with arthroscopic rotator cuff repair, 42 patients who were followed-up serially for 2 years were enrolled as study subjects. The average age of the patients at the time of the operation was 55 years, and the mean duration of follow-up was 34 months. The subjects included 22 cases of PTRCT and 20 cases of FTRCT.

RESULTS

At the final follow-up, the PTRCT group showed changes in scores from 7.2 to 0.9 for average pain and from 34 to 91 for the shoulder functional evaluation score of the American Shoulder and Elbow Society (ASES score). The FTRCT group showed changes in scores from 7.6 to 1.2 for pain and from 29 to 88 for the ASES score. There were no significant differences between the 2 groups ( P >.05). The average range of shoulder motion was significantly improved in both groups at the final follow-up versus their preoperative values. Evaluation at the final follow-up showed that 93% of the total subjects showed good or excellent results, and 95% showed satisfactory results with regard to pain reduction and functional outcomes. The 2 fair results were the result of acromioclavicular arthritis.

CONCLUSIONS

It may be anticipated that arthroscopic rotator cuff repair and subacromial decompression will give satisfactory postoperative outcomes in both PTRCT and FTRCT in terms of pain relief and functional recovery. However, careful preoperative examination of the acromioclavicular joint is critical to avoid procedural failure.

LEVEL OF EVIDENCE

Level IV.

Using base-specific Salmonella tester strains to characterize the types of mutation induced by benzidine and benzidine congeners after reductive metabolism

Although benzidine (Bz), 4-aminobiphenyl (ABP), 3,3'-dichlorobenzidine HCl (DCBz), 3,3'-dimethylbenzidine (DMBz), 3,3'-dimethoxybenzidine (DMOBz) and the benzidine congener-based dye trypan blue (TB) produce primarily frameshift mutations in Salmonella typhimurium, the base-substitution strain TA100 also responds to these compounds when S9 is present. Performing DNA sequence analysis, other investigators have shown that ABP induces frameshift, base-pair and complex mutations. Also, it was found that an uninduced hamster liver S9 preparation with glucose-6-phosphate dehydrogenase, FMN, NADH and four times glucose 6-phosphate gave a stronger mutagenic response than the conventional plate incorporation with rat S9 activation mixture for all the compounds tested. Using the base-specific tester strains of S. typhimurium (TA7001-TA7006) with the above reductive metabolic activation system, we surveyed these compounds for the ability to produce specific base-pair substitutions after reductive metabolism. Bz was weakly mutagenic in TA7005 (0.04 revertants/microg). ABP was mutagenic in TA7002 (1.4 revertants/microg), TA7004 (0.6 revertants/microg), TA7005 (2.98 revertants/microg) and TA7006 (0.4 revertants/microg). DCBz was weakly mutagenic in TA7004 (0.01 revertants/microg). It was concluded that benzidine induced some CG->AT transversions in addition to frameshift mutations. ABP induced TA->AT, CG->AT, and CG->GC transversions as well as GC->AT transitions. DCBz induced only GC->AT transitions. Because DMBz, DMOBz and TB were not mutagenic in this base-substitution mutagen detection system, their mutagenic activity was attributed strictly to frameshift mechanisms.

Response of the ascorbate-peroxidase of Selenastrum capricornutum to copper and lead in stormwaters

The green alga Selenastrum capricornutum expresses a unique ascorbate peroxidase, that responds to copper and lead. Attempts were made to test if this peroxidase could be used to monitor the levels of copper and lead in natural waters. When S. capricornutum was exposed to a stormwater sample, the specific activity of the peroxidase in the cell extract was commensurate with the combined copper and lead contents in the sample. The peroxidase responses were also correlated with the 96 hr biomass toxicity assay of S. capricornutum. However, unlike the biomass toxicity assay, the peroxidase activity was not affected by the anions in the samples. The use of this peroxidase can be used as a marker for testing heavy metal toxicity in the water.

Albert Léon Charles Calmette (1863-1933) and the antituberculous BCG vaccination

Albert Léon Charles Calmette was the first person to develop an anti-venom serum. His work revolutionized the treatment of snakebite in men and domestic animals. He is also well known for his development of the Bacillus Calmette-Guérin (BCG) vaccine for the prevention of tuberculosis. This article reviews the life experiences of this pioneer bioscientist, the current status of BCG in preventing tuberculosis, and the potential of BCG in immunotherapy for cancer.

Mutagenicity studies of benzidine and its analogs: structure-activity relationships

The Ames Salmonella/microsome assay was employed to test the mutagenicity of benzidine and its analogs using strains TA98 and TA100 in the presence and absence of Aroclor 1254-induced rat S9 mix. 3,3'-Dichlorobenzidine-2HCl and 4,4'-dinitro-2-biphenylamine were directly mutagenic to TA98, while 4,4'-dinitro-2-biphenylamine was directly mutagenic to both TA98 and TA100 in the absence of S9 mix. 2-Aminobiphenyl, 3-aminobiphenyl, and 3,3'-5,5'-tetramethylbenzidine were not mutagenic in either strains in the presence or absence of S9. In the presence of S9 mix, 4-aminobiphenyl, benzidine, 3, 3'-dichlorobenzidine-2HCl, 3,3'-dimethoxybenzidine, 3,3'-4, 4'-tetraaminobiphenyl, o-tolidine, N, N-N', N'-tetramethylbenzidine, and 4,4'-dinitro-2-biphenylamine were mutagenic to TA98; 4-aminobiphenyl, 3,3'-dichlorobenzidine-2HCl, 3, 3'-dimethoxybenzidine, and 4,4'-dinitro-2-biphenylamine were mutagenic to TA100. Physicochemical parameters of these compounds including oxidation potentials, the energy difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital, ionization potentials, dipole moment, relative partition coefficient, and basicity did not correlate with their bacterial mutagenic activities.

Effects of dehulled adlay on the culture count of some microbiota and their metabolism in the gastrointestinal tract of rats

Experiments were conducted to study the effect of a dietary supplement of dehulled adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) on the culture counts of some important groups of intestinal bacteria and their metabolism in the gastrointestinal (GI) tract of Sprague-Dawley rats. Rats were divided into four groups, and each group was fed a diet containing different levels of dehulled adlay for 30 days as follows: 0% (control), 5%, 20%, and 40%. All animals fed with adlay had normal healthy intestinal walls and no pathogenic signs whatsoever. There were no significant differences in body weight gain or the cecal pH between different groups of rats. Both the 20% and 40% groups had lower culture counts of enterics in their feces than the 5% and control groups, whereas the culture counts of fecal lactic acid bacteria were higher in feces of rats fed with adlay than in the control group. Cecal total short-chain fatty acid (SCFA) content and fecal SCFA were significantly higher in the 20% and 40% groups than in the control and 5% groups. All the adlay-fed rats had a higher fecal butyric acid concentration than the control rats. It is concluded that adlay has a significant influence on the growth of intestinal bacteria, which may ultimately affect the physiology and other functions of GI tracts of rats.

Viresin. A novel antibacterial protein from immune hemolymph of Heliothis virescens pupae

Immune hemolymph was collected from fifth instar larvae and 1-day-old pupae of Heliothis virescens after injection of prepupae with live Enterobacter cloacae. Induction of antibacterial activity against Escherichia coli K12 D31 was 7.5 times greater in pupal than in larval immune hemolymph. Lysozyme activity of immune pupal hemolymph against Micrococcus lysodeikticus was 11 times greater when compared with lysozyme activity of immune larval hemolymph. Early pupal immune response with regard to antibacterial activity was much greater than larval immune response in H. virescens. Normal pupal hemolymph showed an increase in antibacterial activity and lysozyme that was induced during metamorphosis. Antibacterial protein was isolated together with lysozyme by gel filtration chromatography and then separated from lysozyme by sequential electrophoresis with a native acid gel and SDS gel. Molecular mass of antibacterial protein was estimated to be 12 kDa. The N-terminal amino acid sequence of 12-kDa protein was different from those of antibacterial molecules found in other insects and has not been identified before. A sample containing 12-kDa protein was negative for immunoblotting with anti-synthetic cecropin B antibody. We have named the novel 12-kDa antibacterial protein viresin. Viresin showed antibacterial activity against several Gram-negative bacteria including E. cloacae but not against Gram-positive bacteria.

Mutagenicity and antimutagenicity studies of tannic acid and its related compounds

Tannic acid and its hydrolysed products such as ellagic acid, gallic acid and propyl gallate were tested for mutagenicities using Ames Salmonella tester strains TA98 and TA100. Also, the antimutagenic activities of these compounds against a number of direct mutagens including 2-nitrofluorene (2-NF), 4,4'-dinitro-2-biphenylamine, 1-nitropyrene, 1,3-dinitropyrene, 2-nitro-p-phenylenediamine, 3-nitro-o-phenylenediamine, 4-nitro-o-phenylenediamine were tested. None of these tannic acid compounds was mutagenic. They also failed to show antimutagenic activity towards the tested direct mutagens. However, tannic acid at non-growth inhibitory concentrations reduced the revertant numbers of TA98 in the presence of S9 mix when benzidine, 3,3'-4,4'-tetraminobiphenyl, 4-aminobiphenyl, and N,N-N', N'-tetramethylbenzidine were used as the mutagens. These results suggest that tannic acid, but not its hydrolytic products, affects the metabolic activation of these mutagens.

Postoperative pain relief in primigravida caesarean section patients--combination of intrathecal morphine and epinephrine

BACKGROUND

Uterine contraction is less severe in primigravida patients. Intrathecal coadministration of morphine and epinephrine may provide an easy way of postcaesarean pain control.

METHODS

Twenty-eight primigravida patients who requested postcaesarean pain control were studied for the effectiveness of coadministration of intrathecal morphine and epinephrine. The solution for spinal anesthesia which contained 0.2 mg morphine, 0.1 mg epinephrine and 10 mg hyperbaric bupivacaine was injected intrathecally. Another 30 primigravida patients were collected randomly as control. In the control group, normal saline and 0.1 mg epinephrine were used with bupivacaine. Side effects from intrathecal morphine and the need of analgesia were recorded within 48 h.

RESULTS

In the study group, 89.3% (25/28) of patients did not need further narcotics for pain relief during their hospitalization after caesarean section. 96.4% (27/28) of patients needed only one dose of 50 mg intramuscular meperidine (Demerol) or no narcotic at all for pain relief within 48 h. No respiratory depression occurred. In the control group, each patient received in the average 6-7 doses of 50 mg Demerol for pain control within 48 h.

CONCLUSIONS

Our results showed that 0.2 mg morphine and 0.1 mg epinephrine in combination with 10 mg hyperbaric bupivacaine given intrathecally could provide a simple way of pain control in primigravida patients undergoing caesarean section.

Antimicrobial activity of tea as affected by the degree of fermentation and manufacturing season

Bacillus subtilis, Escherichia coli, Proteus vulgaris, Pseudomonas fluorescens, Salmonella sp. and Staphylococcus aureus were used to test the antimicrobial activity of tea flush extract and extracts of various tea products. Among the six test organisms, P. fluorescens was the most sensitive to the extracts, while B. subtilis was the least sensitive. In general, antimicrobial activity decreased when the extents of tea fermentation increased. The antimicrobial activities of tea flush extract and extracts of tea products with different extents of fermentation varied with test organisms. Tea flush and Green tea, the unfermented tea, exerted the strongest antimicrobial activity followed by the partially fermented tea products such as Longjing, Tieh-Kuan-Ying, Paochung, and Oolong teas. On the other hand, Black tea, the completely fermented tea, showed the least antimicrobial activity. It was also noted that extracts of Oolong tea prepared in summer exhibited the strongest antimicrobial activity, followed by those prepared in spring, winter and fall.

Muscarinic activation causes biphasic inotropic response and decreases cellular Na+ activity in canine cardiac Purkinje fibers

In this study, the effects of carbachol (CCh) on twitch tension, intracellular Na+ activity (aiNa), and action potential were simultaneously measured in canine cardiac Purkinje fibers in order to examine the regulation of inotropy through muscarinic receptors and its relation to aiNa. In fibers driven at 1 Hz, CCh (10 microM) initially and transiently decreased and then increased the twitch tension by 36 +/- 8%. The action potential showed a significant elevation of the plateau and a significant shortening of the duration at 90% repolarization (APD90), from 403 +/- 7 to 389 +/- 7 ms. The aiNa decreased from 7.4 +/- 0.4 to 6.7 +/- 0.3 mM (n = 23, p < 0.05). Atropine (1 microM) decreased the twitch tension by 21 +/- 6% (n = 7, p < 0.05) without significant effects on the action potential and aiNa, and inhibited the effects of CCh. Cs+ (20 mM) increased the plateau height and APD90, enhanced the twitch tension by 66 +/- 24%, but decreased aiNa from 7.3 +/- 0.3 to 6.3 +/- 0.4 mM (n = 6, p < 0.05). In the presence of 20 mM Cs+, some fibers generated slow responses. The addition of 10 microM CCh further increased the twitch tension and APD90, and decreased aiNa from 6.3 +/- 0.4 to 5.3 +/- 0.3 mM. Ouabain (0.3 microM) increased the twitch tension and aiNa, and inhibited the CCh-induced decrease of aiNa. In the presence of ouabain, 20 mM Cs+ depolarized the fiber and generated slow responses with a decreased aiNa. The addition of 10 microM CCh enhanced the slow action potential, and increased aiNa although there was a transient decrease during early exposure. These results suggest that activation of muscarinic receptors in canine Purkinje fibers results in an enhancement of the Na+-K+ pump activity and a biphasic inotropic response, probably via different receptor subtypes. The inhibitory effect, most likely through M2 receptors, is associated with the activation of K+ channels. The stimulatory effect, on the other hand, is probably due to the action on the M1 receptors, resulting in increases in Ca2+ currents.

Mechanism of inhibition of tannic acid and related compounds on the growth of intestinal bacteria

Tannic acid, propyl gallate and methyl gallate, but not gallic acid, were found to be inhibitory to the growth of intestinal bacteria Bacteroides fragilis ATCC 25285, Clostridium clostridiiforme ATCC 25537, C. perfringens ATCC 13124, C. paraputrificum ATCC 25780, Escherichia coli ATCC 25922, Enterobacter cloacae ATCC 13047, Salmonella typhimurium TA98 and S. typhimurium YG1041 at 100-1000 microg/ml in culture broth. Neither Bifidobacterium infantis ATCC 15697 nor Lactobacillus acidophilus ATCC 4356 was inhibited by any of the above compounds up to 500 microg/ml. Tannic acid has a much greater relative binding efficiency to iron than propyl gallate, methyl gallate or gallic acid. The inhibitory effect of tannic acid to the growth of intestinal bacteria may be due to the strong iron binding capacity of tannic acid; whereas the effect of propyl gallate and methyl gallate probably occurs by a different mechanism. The growth of E. coli was restored by the addition of iron to the medium after the precipitate caused by tannic acid was removed. Neither B. infantis nor L. acidophilus require iron for growth. This probably contributes to their resistance to tannic acid. Because tannins are abundant in the human diet, tannins may affect the growth of some intestinal bacteria and thus may have an impact on human health.

Tannins and human health: a review

Tannins (commonly referred to as tannic acid) are water-soluble polyphenols that are present in many plant foods. They have been reported to be responsible for decreases in feed intake, growth rate, feed efficiency, net metabolizable energy, and protein digestibility in experimental animals. Therefore, foods rich in tannins are considered to be of low nutritional value. However, recent findings indicate that the major effect of tannins was not due to their inhibition on food consumption or digestion but rather the decreased efficiency in converting the absorbed nutrients to new body substances. Incidences of certain cancers, such as esophageal cancer, have been reported to be related to consumption of tannins-rich foods such as betel nuts and herbal teas, suggesting that tannins might be carcinogenic. However, other reports indicated that the carcinogenic activity of tannins might be related to components associated with tannins rather than tannins themselves. Interestingly, many reports indicated negative association between tea consumption and incidences of cancers. Tea polyphenols and many tannin components were suggested to be anticarcinogenic. Many tannin molecules have also been shown to reduce the mutagenic activity of a number of mutagens. Many carcinogens and/or mutagens produce oxygen-free radicals for interaction with cellular macromolecules. The anticarcinogenic and antimutagenic potentials of tannins may be related to their antioxidative property, which is important in protecting cellular oxidative damage, including lipid peroxidation. The generation of superoxide radicals was reported to be inhibited by tannins and related compounds. The antimicrobial activities of tannins are well documented. The growth of many fungi, yeasts, bacteria, and viruses was inhibited by tannins. We have also found that tannic acid and propyl gallate, but not gallic acid, were inhibitory to foodborne bacteria, aquatic bacteria, and off-flavor-producing microorganisms. Their antimicrobial properties seemed to be associated with the hydrolysis of ester linkage between gallic acid and polyols hydrolyzed after ripening of many edible fruits. Tannins in these fruits thus serve as a natural defense mechanism against microbial infections. The antimicrobial property of tannic acid can also be used in food processing to increase the shelf-life of certain foods, such as catfish fillets. Tannins have also been reported to exert other physiological effects, such as to accelerate blood clotting, reduce blood pressure, decrease the serum lipid level, produce liver necrosis, and modulate immunoresponses. The dosage and kind of tannins are critical to these effects. The aim of this review is to summarize and analyze the vast and sometimes conflicting literature on tannins and to provide as accurately as possible the needed information for assessment of the overall effects of tannins on human health.

Synthetic peptides of human papillomavirus type 18 E6 harboring HLA-A2.1 motif can induce peptide-specific cytotoxic T-cells from peripheral blood mononuclear cells of healthy donors

To identify cytotoxic T-cell (CTL) epitopes against human papillomavirus type 18 (HPV 18) E6 protein that might be useful for developing peptide-based vaccine against HPV 18 infection, 18 peptides which possibly contain CTL epitopes were selected on the basis of previously described human leukocyte antigen (HLA)-A2.1-binding motif and chemically synthesized. In the binding assay of the synthetic peptides, 8 out of 18 synthetic peptides enhanced the expression of HLA-A2.1 molecules on T2 cell surface, which implies that these peptides were able to bind the HLA molecules. Those peptides having good binding affinity to HLA-A2.1 were tested for their ability to activate CTLs which were isolated from peripheral blood mononuclear cells (PBMCs) of healthy blood donors and to kill the target T2 cells pulsed with the same peptide. Five out of eight tested peptides activated CTLs and killed the target cells.

Base-pair mutation caused by four nitro-group containing aromatic amines in Salmonella typhimurium TA100, TA104, TA4001 and TA4006

Among p-phenylenediamine, benzidine and the analogues we previously tested, only the nitro-group containing 2-nitro-p-phenylenediamine, 3-nitro-o-phenylenediamine, 4-nitro-o-phenylenediamine and 4,4'-dinitro-2-biphenylamine caused base-pair reversion in the histidine locus of Salmonella typhimurium TA100. In order to determine the types of mutations involved, such as transversion or transition, these four nitro-group containing compounds were tested with S. typhimurium strains TA100, TA104, TA4001 and TA4006. Dose-mutagenicity relationships occurred with TA100 and TA104. However, the majority of revertants from TA100 and TA104 were insensitive to inhibition by histidine analogue, DL-1,2,4-triazole-3-alanine. These results suggested that the occurrence of histidine revertants was predominantly induced by base-pair (point) mutations and not by suppressor gene mutations. The CG-TA transition and CG-AT transversion are the major types of mutation induced by all these compounds in TA100. The TA-AT transversion also contributed to the mutagenicity of 4-nitro-o-phenylenediamine and 4,4'-dinitro-2-biphenylamine in TA104. These nitro-group containing compounds showed no mutagenicity in TA4001, but induced CG-GC transversion in TA4006.

Review of mutagenicity of monocyclic aromatic amines: quantitative structure-activity relationships

Monocyclic aromatic amines (MAAs) are environmental pollutants. Many of them are genotoxic and impose hazards to human health. The mutagenicity of more than 80 of these amines was reviewed with primary emphasis on evaluation by the Ames Salmonella/microsome testing system. Many amines are mutagenic in Salmonella tester strains TA98 and TA100, but S9 mix is required for activity for most of the active ones. 2,4-Diaminotoluene, 2,4-diaminoethylbenzene, and a few amines containing a nitro-group are direct mutagens. There are several quantitative structure-activity relationship (QSAR) models which rationalize mutagenicity of many aromatic amines and several parameters, such as the lowest unoccupied molecular orbital energy (ELUMO), highest occupied molecular orbital energy (EHOMO), and hydrophobicity that are important. What factors determine the minimum requirement for the compound to be mutagenic and what factors determine the extent of mutagenicity suggest questions for further study.

Dietary restriction modulated carcinogen-DNA adduct formation and the carcinogen-induced DNA strand breaks

Dietary restriction (DR) alters the activities of hepatic drug metabolizing enzymes and modulates the formation of carcinogen-DNA adducts in carcinogen treated animals. Our previous results showed that a 40% restriction of diet (60% of ad libitum (AL) food consumption) reduced the hepatic metabolic activation of aflatoxin B1 (AFB1) but increased the activation of benzo[a]-pyrene (BaP) in both rats and mice. In this study, the focus was directed toward the levels of carcinogen-DNA adducts formation and the carcinogen-induced DNA strand breaks in mouse kidney and liver DNA. DR significantly inhibited both AFB1-DNA adduct formation and AFB1-induced DNA strand breaks in kidney DNA of mice that received a single dose of [3H]AFB1 (5 mg/kg). The levels of AFB1-DNA adduct formation in mouse kidney DNA correlated well with increased AFB1-induced DNA strand breaks. The correlation between the levels of AFB1-DNA-adducts formed and DNA strand breaks in kidney DNA of DR-mice was less linear than between its AL-counterpart suggesting that other factors, such as different rates of DNA repair, may be involved. In addition, DR enhanced hepatic BaP- and 6-nitrochrysene (6-NC)-DNA adduct formation in the mice treated with BaP and 6-NC, respectively. The formation of the specific BaP-adduct, 10-(N2-deoxyguanosinyl)-7,8,9-trihydroxy-7,8,9,10-tetrahydro-BaP (N2-dG-BaP), in mouse liver was proportional to the dose, and was compatible to the BaP-induced DNA strand breaks affected by DR. The enhancement of the total 6-NC-DNA adduct formation in DR-mouse was also in correlation with the increased 6-NC-induced DNA strand breaks. The activity of mouse liver microsomal nitro-reductase increased by 2-fold in response to DR indicating that the nitroreduction may contribute to the increase of the metabolic activation of 6-NC. Our present results indicate that the effect of DR on the carcinogen activation is dependent upon the DR-modulated carcinogen metabolizing enzyme activities.

Simultaneous effects of carbachol on intracellular Na+ activity, action potential, and twitch tension in guinea-pig cardiac ventricular papillary muscles

Effects of carbachol (CCh) on the twitch tension, intracellular Na+ activity (aNai), and action potential were simultaneously measured in guinea-pig cardiac ventricular papillary muscles. In fibers driven at 60 beats/min, 100 microM CCh significantly increased the twitch tension and aNai, and decreased the action potential duration at 30 and 90% repolarization (APD30 and APD90) without changing the maximum rate of the rise of the upstroke (Vmax). Staurosporine (1 microM) alone gradually decreased the twitch tension and aNai without changing the action potential. In the presence of staurosporine, the administration of CCh restored aNai and caused the same changes in twitch tension and APD shortening with no effect on Vmax. Pretreatment with 1 microM atropine completely eliminated the effects of 100 microM CCh. Cesium (20 mM) depolarized the cell membrane and significantly increased the twitch tension and APD90 with decreases in the Vmax and aNai. CCh (100 microM) in the presence of 20 mM Cs+ biphasically decreased and increased the twitch tension and significantly decreased the Vmax and aNai with an increase in the APD90. The results suggest that the muscarinic receptor-mediated increase of aNai is protein kinase C-independent. The aNai increase is associated with the positive inotropic effect and the abbreviation of the action potential duration. In addition to the increase in aNai, the increase of the myofibrillar calcium sensitivity involved is responsible for the positive inotropic effect which is still evident after the sodium influx is inhibited by Cs+.

Effect of dietary restriction on benzo[a]pyrene (BaP) metabolic activation and pulmonary BaP-DNA adduct formation in mouse

Hepatic microsomal xenobiotic metabolizing enzyme activities of laboratory animals can be modulated by Dietary restriction (DR). The modulation of xenobiotic metabolizing enzyme activities can affect the metabolic activation of chemical carcinogens. Acute DR (60% of the food consumption of ad libitum (AL)-fed mice for 7 weeks) reduced the body weights of the male B6C3F1 mice, and increased mouse pulmonary cytochrome P4501A1-dependent BaP metabolizing enzyme activity. The effects of DR on the formation of the specific BaP-DNA adduct, 10-(N2-deoxyguanosinyl)-7,8,9-trihydroxy-7,8,9,10-tetrahydro-BaP (BaP-N2-dG) in mouse lung can be detected by using 32P-postlabeling technique. In both AL- and DR-mice total BaP-DNA adduct formation in lung reached a peak at 48 hours after treatment with [3H]BaP and the in vivo formation of BaP-N2-dG was greater in DR mouse lung than in that of AL-animals by 22%. DR increased in vitro BaP-N2-dG formation by 39% when calf-thymus DNA was incubated with BaP using liver microsomes obtained from DR- or AL-mice as the enzyme source. The formation of the specific BaP-N2-dG adducts, measured by 32P-postlabeling, was only 20% of the total [3H]BaP-DNA adducts as determined by liquid scintillation counting. The increase of BaP-DNA adduct formation in mouse lung was correlated to the enhancement of the mouse pulmonary BaP metabolizing enzyme activity. Our results indicated that the effect of DR on the metabolic activation of BaP in mouse lung was dependent upon the mouse lung cytochrome P4501A1-dependent BaP metabolizing enzymes activities which was significantly increased by DR.

Effects of the nitro-group on the mutagenicity and toxicity of some benzamines

The Ames Salmonella/microsomal assay was employed to test the mutagenicity of some benzamines (aniline, and o- and p-phenylenediamine) and their nitro-derivatives (p-nitroaniline, 2-nitro-p-phenylenediamine, 3- and 4-nitro-o-phenylenediamine), using strains TA98 and TA100 and their nitroreductase-deficient mutants, TA98NR and TA100NR, in the presence and absence of rat S9 mix. The addition of the nitro-group to benzamine molecules converted them into direct mutagens. Furthermore, the position of the nitro-group affected their mutagenic activities. Cytotoxicity testing with Chinese hamster ovary cells (CHO-K1) showed that the presence of the nitro-group in these compounds had no specific effect on toxicity. The test compounds all showed a dose-related increase in inducing chromosomal aberrations in CHO cells. However, the presence of the nitro-group did not affect potency in inducing chromosomal aberrations. Compounds containing the nitro-group had higher initial oxidation potentials and dipole moments (mu) than their nonnitro-containing counterparts. The mutagenicity and toxicity of these compounds were not related to physico-chemical properties, including oxidation potential, energy difference (deltaE) between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO), ionization potential (I.P.), and mu.

Mutagenicity and toxicity studies of p-phenylenediamine and its derivatives

The mutagenicity of p-phenylenediamine and its derivatives was tested using Ames Salmonella strains TA98 and TA100. p-Phenylenediamine was weakly mutagenic to TA98 with metabolic activation. 2-Nitro-p-phenylenediamine was directly mutagenic to both strains, while 2-methyl-p-phenylenediamine required S9 mix. All the test compounds induced a dose-related increase in chromosomal aberrations in Chinese hamster ovary (CHO) cells in the absence of the S9 mix. The mutagenicity and toxicity of these compounds did not correlate with their oxidation potentials, or any other tested physicochemical properties including the energy difference between the lowest unoccupied and the highest occupied molecular orbital, ionization potential, and dipole moment.

Effect of dietary restriction on glutathione S-transferase activity specific toward aflatoxin B1-8,9-epoxide

Dietary restriction (DR) reduced the metabolic activation of aflatoxin B1 (AFB1) in rats. This reduction may be attributed to the decrease of cytochrome P-450-mediated AFB1 epoxidation and/or increase in the detoxification of AFB1 catalyzed by hepatic glutathione S-transferase (GST) and other phase II detoxification enzymes. In this study the effect of DR on male rat liver cytosolic GST activity toward AFB1-8,9-epoxide was studied. The chemically-synthesized AFB1-8,9-epoxide was used as the substrate in this assay, and the formation of AFB1-GSH conjugate was analyzed by HPLC. Male Fischer 344 rats fed DR diets (60% of the food consumption of ad libitum (AL)-fed rats) showed a 2.4-fold increase in GST activity when AFB1-epoxide was used as the substrate. The results from the enzyme kinetic study showed that DR increased Vmax of the liver cytosolic GST but not the Km. Acute DR has little or no impact on GST activity when 1-chloro-2,4-dinitrobenzene and 2,4-dichloronitrobenzene were used as substrates. The mouse liver GST activity toward AFB1-epoxide was 3-fold greater than that of phenobarbital-induced rats, 4.5-fold greater than DR rats, and 14.7-fold greater than the GST activity of AL rats. This direct assay of liver GST activity using AFB1-epoxide as the substrate is useful for studying AFB1-induced biomarkers, such as AFB1-GSH conjugation and AFB1-DNA adducts.

Effect of caloric restriction on the metabolic activation of xenobiotics

The effect of caloric restriction (CR) on xenobiotic metabolizing enzyme activities results in alterations in the metabolic activation of chemical carcinogens, with a resultant impact on DNA-carcinogen adduct formation and DNA repair. Using aflatoxin B1 (AFB1) and benzo[a]pyrene (BP) as model carcinogens, we studied the effect of CR on the metabolic activation of these carcinogens and carcinogen-induced DNA damage and repair in terms of AFB1-DNA and BP-DNA adduct formation and removal. Male Fischer 344 rats fed calorie restricted diets (60% of the food consumption for ad libitum-fed rats) showed a reduction in the metabolic activation of AFB1 and decrease in both the in vitro and in vivo AFB1-DNA adduct formation. However, CR increased the activity of BP metabolizing enzymes resulting in an enhancement of BP-DNA adduct formation. Our results indicate that the effect of CR on metabolic activation of xenobiotics is dependent upon the selected xenobiotic metabolizing enzymes whose activities may be significantly altered by CR, and upon the nature of the chemical carcinogens which exert different structure-activity relationships during the process of chemically induced carcinogenesis.