Metabolomic Analysis of Microcystis aeruginosa After Exposure to the Algicide L-Lysine

The widespread occurrence of cyanobacteria blooms damages the water ecosystem and threatens the safety of potable water and human health. Exogenous L-lysine significantly inhibits the growth of a dominant cyanobacteria Microcystis aeruginosa in freshwater. However, the molecular mechanism of how lysine inhibits the growth of M. aeruginosa is unclear. In this study, both non-target and target metabolomic analysis were performed to investigate the effects of algicide L-lysine. The results showed that 8 mg L^- 1 lysine most likely disrupts the metabolism of amino acids, especially the arginine and proline metabolism. According to targeted amino acid metabolomics analysis, only 3 amino acids (L-arginine, ornithine, and citrulline), which belong to the ornithine-ammonia cycle (OAC) in arginine metabolic pathway, showed elevated levels. The intracellular concentrations of ornithine, citrulline, and arginine increased by 115%, 124%, and 19.4%, respectively. These results indicate that L-lysine may affect arginine metabolism and OAC to inhibit the growth of M. aeruginosa.

The neurotoxicity of Nε-(carboxymethyl)lysine in food processing by a study based on animal and organotypic cell culture

Nε-(carboxymethyl)lysine (CML) is a potentially noxious compound that is causing widespread concern due to its use in various food products. In this study, we investigated CML neurotoxicity via an in vivo experiment with mice, and an in vitro experiment using a 3D microvascular network model (with human brain vascular endothelial cell and human astrocyte) that simulated the blood-brain barrier. We found that CML could induce cell survival status variations, and histopathological changes to the brain. In addition, CML increased levels of oxidative stress, prompted the protein expression of the receptor for advanced glycation end-products (RAGE). CML up-regulated both the gene expression of RAGE, the activating protein-1 (AP-1), the inflammatory cytokines Interleukin-6 (IL-6), vascular cell adhesion molecule1 (VCAM-1), monocyte chemotactic protein1 (MCP-1). We, therefore, postulated that CML has the potential to deleteriously affect the nervous system through oxidative stress and that activation of the p38 MAPK-AP-1 signaling pathway might be implicated in this pathological process.

Identification of a 5-Hydroxymethylfurfural-Lysine Schiff Base and Its Cytotoxicity in Three Cell Lines

5-Hydroxymethylfurfural (HMF) can undergo the Maillard reaction with amino acids. However, the safety of the products remains unknown. In this study, a HMF-lysine Schiff base named (E)-N⁶-((5'-(hydroxymethyl)furan-2'-yl)methylene)lysine (HML) was identified and detected for the first time in baked foods. HML formation significantly decreased the cytotoxicity (IC₅₀) of HMF against GES-1 cells (81.81 versus 5.02 mM and 73.76 versus 2.94 mM for HML versus HMF at 24 and 48 h, respectively), EA.hy926 cells (86.05 versus 4.85 mM and 77.22 versus 0.71 mM, respectively), and Caco-2 cells (155.77 versus 36.84 mM and 112.70 versus 18.51 mM, respectively). Exposure of Caco-2 cells to HMF at 10.0 mM triggered cell apoptosis of 14.02% (versus 8.54% in the control), whereas exposure to HML at 10-15 mM hardly increased cell apoptosis. Moreover, the absorption capacities of HMF and HML by Caco-2 cells were equivalent (p > 0.05) at 7.23-12.57% after incubation at 2 mM for 30-150 min.

Furosine Posed Toxic Effects on Primary Sertoli Cells through Regulating Cep55/NF-κB/PI3K/Akt/FOX01/TNF-α Pathway

As one of the Maillard reaction products, furosine has been widely reported in a variety of heat-processed foods, while the toxicity of furosine on the reproductive system and related mechanisms are unclear. Here, we constructed an intragastric gavage male mice model (42-day administration, 0.1/0.25/0.5 g furosine/Kg body weight per day) to investigate its effects on mice testicle index, hormones in serum, and mice sperm quality. Besides, the lipid metabonomics analysis was performed to screen out the special metabolites and relatively altered pathways in mice testicle tissue. Mice primary sertoli cells were separated from male mice testicle to validate the role of special metabolites in regulating pathways. We found that furosine affected testicle index, hormones expression level and sperm quality, as well as caused pathological damages in testicle tissue. Phosphatidylethanolamine (PE) (18:0/16:1) was upregulated by furosine both in mice testicle tissue and in primary sertoli cells, meanwhile, PE(18:0/16:1) was proved to activate Cep55/NF-κB/PI3K/Akt/FOX01/TNF-α pathway, and as a functional protein in dairy products, lactoferrin could inhibit expression of this pathway when combined with furosine. In conclusion, for the first time we validated that furosine posed toxic effects on mice sperms and testicle tissue through upregulating PE(18:0/16:1) and activating Cep55/NF-κB/PI3K/Akt/FOX01/TNF-α pathway.

Effects of flavor enhancers on the survival and behavior of the red imported fire ant, Solenopsis invicta (Hymenoptera: Formicidae)

To understand whether flavor enhancers pose potential risks to the environment, it is important to assess its effects on insects. Therefore, the objective of this study was to evaluate the toxicity of flavor enhancers on the survival and behaviors of the red imported fire ant, Solenopsis invicta. In this study, we found that the mortality of S. invicta workers that were fed glutamic acid monosodium salt hydrate, glycine, L-alanine, succinic acid, succinic acid disodium, inosinate 5'-monophosphate disodium salt hydrate, and GMP were significantly higher than the mortality rates of workers fed sucrose. Moreover, glycine and GMP exhibited the strongest toxicities and caused 100% mortality in workers after 84 h. LC₅₀ values were 0.004 g/ml and 0.02 g/ml for GMP and glycine, respectively. Additionally, at sublethal doses, both GMP and glycine solutions decreased foraging and digging behaviors. Our results suggest that flavor enhancers are toxic to insects and also likely to have a negative impact at sublethal concentrations.

Novel α-Oxoamide Advanced-Glycation Endproducts within the N6-Carboxymethyl Lysine and N6-Carboxyethyl Lysine Reaction Cascades

The highly reactive α-dicarbonyl compounds glyoxal and methylglyoxal are major precursors of posttranslational protein modifications in vivo. Model incubations of N²-t-Boc-lysine and either glyoxal or methylglyoxal were used to further elucidate the underlying mechanisms of the N⁶-carboxymethyl lysine and N⁶-carboxyethyl lysine reaction cascades. After independent synthesis of the authentic reference standards, we were able to detect N⁶-glyoxylyl lysine and N⁶-pyruvoyl lysine for the first time by HPLC-MS² analyses. These two novel amide advanced-glycation endproducts were exclusively formed under aerated conditions, suggesting that they were potent markers for oxidative stress. Analogous to the well-known Strecker degradation pathway, leading from amino acids to Strecker acids, the oxidation of an enaminol intermediate is suggested to be the key mechanistic step. A highly sensitive workup for the determination of AGEs in tissues was developed. In support of our hypothesis, the levels of N⁶-glyoxylyl lysine and N⁶-pyruvoyl lysine in rat livers indeed correlated with liver cirrhosis and aging.

In Vitro Evaluation of Cytotoxicity and Permeation Study on Lysine- and Arginine-Based Lipopeptides with Proven Antimicrobial Activity

Owing to their excellent antimicrobial activities with a relatively low cost of production, lipopeptides are being intensively investigated as potential alternatives to popular antimicrobials. However, a critical obstacle for their application is a relatively high toxicity, hence a lot of attention has been paid to designing new molecules with optimal properties. In this study we synthesized the following lipopeptides: C₁₆-KK-NH₂, C₁₆-KεK-NH₂, C₁₆-KKK-NH₂, C₁₆-KRK-NH₂, C₁₆-RR-NH₂, C₁₆-RRR-NH₂, (C₁₀)₂-KKKK-NH₂ and (C₁₂)₂-KKKK-NH₂. Their antimicrobial activity against representative strains of Gram-positive bacteria, Gram-negative bacteria and fungi has been confirmed. The compounds have been evaluated with regard to the safety of their application in dermatology. The cytotoxicity was determined in HaCaT keratinocytes using MTT assay, whereas Strat M membranes placed in Franz diffusion cells were used to assess their ability to skin permeation. The compounds containing one hexadecanoic acid chain turned out to be very toxic towards human keratinocytes, while lipopeptides containing two fatty acid chains (decanoic and dodecanoic) demonstrated much lower cytotoxicity. For the most promising lipopeptide, (C₁₀)₂-KKKK-NH₂, the measured IC₅₀ on HaCaT keratinocytes was few times higher as compared to MICs obtained for the tested bacteria. Both groups of lipopeptides did not permeate the model membranes and therefore lack of permeation through human skin could be expected. The results of this work encourage further research on the potential application of lipopeptides with two fatty acids as novel antimicrobials.

Vitamins D3 and K2 may partially counterbalance the detrimental effects of pentosidine in ex vivo human osteoblasts

Osteoporosis is a metabolic multifaceted disorder, characterized by insufficient bone strength. It has been recently shown that advanced glycation end products (AGEs) play a role in senile osteoporosis, through bone cell impairment and altered biomechanical properties. Pentosidine (PENT), a wellcharacterized AGE, is also considered a biomarker of bone fracture. Adequate responses to various hormones, such as 1,25-dihydroxyvitamin D₃, are prerequisites for optimal osteoblasts functioning. Vitamin K₂ is known to enhance in vitro and in vitro vitamin D-induced bone formation. The aim of the study was to assess the effects of Vitamins D₃ and K₂ and PENT on in vitro osteoblast activity, to convey a possible translational clinical message. Ex vivo human osteoblasts cultured, for 3 weeks, with vitamin D₃ and vitamin K₂ were exposed to PENT, a well-known advanced glycoxidation end product for the last 72 hours. Experiments with PENT alone were also carried out. Gene expression of specific markers of bone osteoblast maturation [alkaline phosphatase, ALP; collagen I, COL Iα1; and osteocalcin (bone-Gla-protein) BGP] was measured, together with the receptor activator of nuclear factor kappa-B ligand/osteoproteregin (RANKL/OPG) ratio to assess bone remodeling. Expression of RAGE, a well-characterized receptor of AGEs, was also assessed. PENT+vitamins slightly inhibited ALP secretion while not affecting gene expression, indicating hampered osteoblast functional activity. PENT+vitamins up-regulated collagen gene expression, while protein secretion was unchanged. Intracellular collagen levels were partially decreased, and a significant reduction in BGP gene expression and intracellular protein concentration were both reported after PENT exposure. The RANKL/OPG ratio was increased, favouring bone reabsorption. RAGE gene expression significantly decreased. These results were confirmed by a lower mineralization rate. We provided in vitro evidence that glycoxidation might interfere with the maturation of osteoblasts, leading to morphological modifications, cellular malfunctioning, and inhibition of the calcification process. However, these processes may be all partially counterbalanced by vitamins D₃ and K₂. Therefore, detrimental AGE accumulation in bone might be attenuated and/or reversed by the presence or supplementation of vitamins D₃ and K₂.

Aryl-Alkyl-Lysines: Agents That Kill Planktonic Cells, Persister Cells, Biofilms of MRSA and Protect Mice from Skin-Infection

Development of synthetic strategies to combat Staphylococcal infections, especially those caused by methicillin resistant Staphyloccus aureus (MRSA), needs immediate attention. In this manuscript we report the ability of aryl-alkyl-lysines, simple membrane active small molecules, to treat infections caused by planktonic cells, persister cells and biofilms of MRSA. A representative compound, NCK-10, did not induce development of resistance in planktonic cells in multiple passages and retained activity in varying environments of pH and salinity. At low concentrations the compound was able to depolarize and permeabilize the membranes of S. aureus persister cells rapidly. Treatment with the compound not only eradicated pre-formed MRSA biofilms, but also brought down viable counts in bacterial biofilms. In a murine model of MRSA skin infection, the compound was more effective than fusidic acid in bringing down the bacterial burden. Overall, this class of molecules bears potential as antibacterial agents against skin-infections.

Increased accumulation of protein-bound N(ε)-(carboxymethyl)lysine in tissues of healthy rats after chronic oral N(ε)-(carboxymethyl)lysine

In recent years, chronic diseases related to advanced glycation end products (AGEs) have attracted more attention. Because diet is an important exogenous source of AGEs, this study aimed to investigate the effects of chronic oral administration of pure N(ε)-(carboxymethyl)lysine (CML) (a major AGE) at 60 mg kg(-1) per day on healthy Sprague-Dawley rats. After administration for 12 weeks, the levels of protein-bound CML were increased to 202 ± 17, 167 ± 47, 217 ± 44, 107 ± 4, 144 ± 23, and 33 ± 7 μg/g dry matter in the kidneys, heart, liver, lungs, spleen, and pancreas, respectively, in comparison with control values of 98 ± 1, 90 ± 15, 140 ± 42, 76 ± 18, 115 ± 15, and 30 ± 4 μg/g dry matter. The difference was significant (p < 0.05) for the kidneys, heart, liver, and lungs, whereas no significant increase was seen in the spleen and pancreas. Furthermore, serum blood urea nitrogen (BUN), creatinine (CREA), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) values increased significantly (p < 0.05), as evidence of impaired kidney and liver function. Additionally, the rats' fasting blood glucose (FBG) levels remained within the normal range, indicating that chronic intake of CML does not promote a rise in blood glucose. These results clearly indicate that a CML-rich diet might be a potential health risk in humans, particularly with respect to kidney and liver function.

Cytotoxicity and pro-inflammatory action of chemo-mechanical caries-removal agents against oral cells

BACKGROUND

Chemo-mechanical caries removal eliminates the outermost portion of the infected layer, leaving behind healthy dentine surfaces, with scarce dental tissue damage; however, the safety of caries solvents has not been established. The aim of the present study was to investigate the possible cytotoxicity of two popular chemo-mechanical caries removal agents.

MATERIALS AND METHODS

The cytotoxicity of Carisolv, Papacarie Duo and control vehicle solution (0.155-20% v/v) against human oral squamous cell carcinoma cells (HCS-2, HSC-3, HSC-4, Ca9-22) human gingival fibroblast (HGF), pulp (HPC) and periodontal ligament fibroblast (HPLF) was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Prostaglandin E2 (PGE2) was quantified by enzyme-linked immunosorbent assay. Changes in fine cell structure were assessed by transmission electron microscopy.

RESULTS

Carisolv exhibited neither cytotoxicity nor hormetic growth stimulation. Papacarie Duo significantly reduced the viable cell number within 30 min. HSC-4 exhibited the highest sensitivity, followed by HSC-2>HSC-3>HPLF>Ca9-22>HPC>HGF cells. Interleukin-1β (3 ng/ml) stimulated HGF, but not HPC cells to produce PGE2 in the culture medium. Papacarie Duo stimulated HGF cells to produce PGE2 in synergistic fashion with interleukin-1β.

CONCLUSION

Carisolv had acceptable biocompatibility with both normal and cancerous oral cells. On the other hand, Papacarie Duo had a rapid but slight cytotoxicity and pro-inflammatory action against oral cells, suggesting the importance of careful application of this agent.

Graptopetalum paraguayense and resveratrol ameliorates carboxymethyllysine (CML)-induced pancreas dysfunction and hyperglycemia

Hyperglycemia is associated with advanced glycation end products (AGEs). Recently, AGEs were found to cause pancreatic damage, oxidative stress, and hyperglycemia through the AGE receptor. Carboxymethyllysine (CML) is an AGE but whether it induces pancreatic dysfunction remains unclear. Graptopetalum paraguayense, a vegetable consumed in Taiwan, has been used in folk medicine and is an antioxidant that protects against liver damage. We investigated the protective properties of G. paraguayense 95% ethanol extracts (GPEs) against CML-induced pancreatic damage. The results indicated that resveratrol, GPE, and gallic acid (the active compound of GPE) increased insulin synthesis via upregulation of pancreatic peroxisome proliferator activated-receptor-γ (PPARγ) and pancreatic-duodenal homeobox-1 (PDX-1) but inhibited the expression of CML-mediated CCAAT/enhancer binding protein-β (C/EBPβ), a negative regulator of insulin production. Moreover, resveratrol and GPE also strongly activated nuclear factor-erythroid 2-related factor 2 (Nrf2) to attenuate oxidative stress and improve insulin sensitivity in the liver and muscle of CML-injected C57BL/6 mice and resulted in reduced blood glucose levels. Taken together, these findings suggested that GPE and gallic acid could potentially be used as a food supplement to protect against pancreatic damage and the development of diabetes.

Cryoprotection of fibroblasts by carboxylated poly-L-lysine upon repeated freeze/thaw cycles

The cryoprotection of carboxylated h-poly-L-lysine (COOH-PLL) was investigated on fibroblasts [L-929 cells and human dermal fibroblasts (HDFs)] during multiple freeze/thaw cycles. COOH-PLL was not toxic to two fibroblast cell types even at 25% (w/v) concentration, whereas dimethylsulphoxide (DMSO) was highly toxic over 3.13% (v/v). When L-929 cells were subjected to 5 freeze/thaw cycles, the media containing 7.5% (w/v) COOH-PLL maintained cell morphology and significantly suppressed growth inhibition as well as cell detachment (P < 0.05). The result was comparable to the media containing 10% (v/v) DMSO. For HDFs, COOH-PLL could effectively retain cell viability and proliferation against 3 freeze/thaw cycles. Cell viability of HDFs was decreased after 5 freeze/thaw cycles, but COOH-PLL exerted better cryoprotection. The cell type might account for the difference in the observations. The data demonstrated that COOH-PLL is a good cryoprotectant for mammalian cells against repeated freeze/thaw cycles, and may be used for cell preservation in fields of cell transplantation, tissue engineering and regenerative medicine.

[Preparation, characterization and Calu-3 cellular uptake of three kinds of poly(b-benzyl-L-amino)block-poly(ethylene glycol) nanoparticles]

The aim of this paper is to compare the cytotoxicity and cellular uptake efficiency of three kinds of poly(b-benzyl-L-amino) block-poly(ethylene glycol) nanoparticles (PXA-PEG-NPs) using Calu-3 cells, and select one as a nasal drug delivery vector for curcumin (Cur). Poly(gamma-benzyl-L-glutamate) block-poly(ethylene glycol) nanoparticles (PBLG-PEG-NPs), poly(gamma-benzyl-L-lysine) block-poly(ethyleneglycol) nanoparticles (PZLL-PEG-NPs) and poly(gamma-benzyl-L-aspartate) block-poly(ethylene glycol) nanoparticles (PBLA-PEG-NPs) were prepared by emulsion-solvent evaporation method. MTT assays were used to evaluate the cytotoxicity of PXA-PEG-NPs against Calu-3 cells. The cellular uptake of nanoparticles was visualized by an inverted fluorescence microscope and quantified by a flow cytometer. The results indicated that even at high concentration of 2 mg x mL(-1) the three nanoparticles had no cytotoxicity on Calu-3 cells. Compared to the curcumin solution, the three curcumin-loaded PXA-PEG-NPs showed significantly higher cellular uptake efficiency on Calu-3 cells (at equal concentration of curcumin with 5 microg x mL(-1) Cur solution), PBLG-PEG-NPs group was the highest. The cellular uptake increased with incubation time, and has positive correlation with nanoparticle concentration. In brief, PXA-PEG-NPs are conducive to delivery Cur into cells, and PBLG-PEG-NPs might be provided as a good nasal drug delivery carrier.

Quantitative analysis of histone modifications: formaldehyde is a source of pathological n(6)-formyllysine that is refractory to histone deacetylases

Aberrant protein modifications play an important role in the pathophysiology of many human diseases, in terms of both dysfunction of physiological modifications and the formation of pathological modifications by reaction of proteins with endogenous electrophiles. Recent studies have identified a chemical homolog of lysine acetylation, N⁶-formyllysine, as an abundant modification of histone and chromatin proteins, one possible source of which is the reaction of lysine with 3′-formylphosphate residues from DNA oxidation. Using a new liquid chromatography-coupled to tandem mass spectrometry method to quantify all N⁶-methyl-, -acetyl- and -formyl-lysine modifications, we now report that endogenous formaldehyde is a major source of N⁶-formyllysine and that this adduct is widespread among cellular proteins in all compartments. N⁶-formyllysine was evenly distributed among different classes of histone proteins from human TK6 cells at 1–4 modifications per 10⁴ lysines, which contrasted strongly with lysine acetylation and mono-, di-, and tri-methylation levels of 1.5-380, 5-870, 0-1400, and 0-390 per 10⁴ lysines, respectively. While isotope labeling studies revealed that lysine demethylation is not a source of N⁶-formyllysine in histones, formaldehyde exposure was observed to cause a dose-dependent increase in N⁶-formyllysine, with use of [¹³C,²H₂]-formaldehyde revealing unchanged levels of adducts derived from endogenous sources. Inhibitors of class I and class II histone deacetylases did not affect the levels of N⁶-formyllysine in TK6 cells, and the class III histone deacetylase, SIRT1, had minimal activity (<10%) with a peptide substrate containing the formyl adduct. These data suggest that N⁶-formyllysine is refractory to removal by histone deacetylases, which supports the idea that this abundant protein modification could interfere with normal regulation of gene expression if it arises at conserved sites of physiological protein secondary modification.

Oxidative stress and inflammation lead to the generation of a multitude of electrophiles in cells that in turn react with nucleophilic macromolecules such as DNA, RNA, polyunsaturated fatty acids, and proteins, leading to progression of a variety of disorders and diseases. Emerging evidence points to widespread modification of cellular proteins by N⁶-formylation of lysine as a result of adventitious reactions with endogenous electrophiles. N⁶-Formyllysine is a chemical homolog of the biologically important N⁶-acetyllysine and thus may interfere with acetylation signaling in cells. While N⁶-formyllysine adducts are now well recognized as abundant protein modifications in cells, the source of these pathological adducts remains unclear. Our previous study proposed N⁶-formylation of lysine in histone proteins occurred by reaction of lysine with 3′-formylphosphate residues arising from DNA oxidation. Here, we investigate additional sources as well as the fate of this abundant pathological protein modification. Our results reveal that endogenous formaldehyde is a major source of N⁶-formyllysine and that this adduct is widely distributed among proteins in all cell compartments. We also demonstrate for the first time that N⁶-formyllysine modifications do not undergo appreciable removal by histone deacetylases, which suggests that they persist in proteins and possibly interfere with the signaling functions at conserved lysine positions in histone proteins.

Lysine triggers apoptosis through a NADPH oxidase-dependent mechanism in human renal tubular cells

Progressive chronic kidney disease (CKD) is common in lysinuric protein intolerance (LPI), a primary inherited aminoaciduria characterized by massive Lysine excretion in urine. However, by which mechanisms Lysine may cause kidney damage to tubule cells is still not understood. This study determined whether Lysine overloading of human proximal tubular cells (HK-2) in culture enhances apoptotic cell loss and its associated mechanisms. Overloading HK-2 with Lysine levels reproducing those observed in urine of patients affected by LPI (10 mM) increased apoptosis (+30%; p < 0.01 vs.C), as well as Bax and Apaf-1 expressions (+30-50% p < 0.05), while downregulated Bcl-2 (-40% p < 0.05). Apoptosis induced by high Lysine was no longer observed after addition of caspase-9 and caspase-3 inhibitors while caspase-8 inhibitor had no protective effect. High Lysine induced elevations in ROS generation and NADPH oxidase subunits mRNAs (p22 (phox) +106 ± 23%, p67 (phox) +108 ± 22% and gp91 (phox) +75 ± 4% p < 0.05-0.01). In addition, the NADPH oxidase inhibitor DPI prevented both ROS production and apoptosis. Treating HK-2 with antioxidants, such as Cysteine and its analog, N-acetyl-L-cysteine (NAC), rescued the HK-2 from apoptosis induced by Lysine. In summary, our data show that high Lysine in vitro increases the permissiveness of proximal tubule kidney cells to apoptosis by triggering a pathway involving NADPH oxidase signaling. This event may represent a key cellular effect in the increasing the susceptibility of human tubular cells to apoptosis when the tubules cope with a high Lysine load. This effect is instrumental to renal damage and disease progression in patients with LPI.

A novel cationic liposome formulation for efficient gene delivery via a pulmonary route

The clinical success of gene therapy for lung cancer is not only dependent on efficient gene carriers but also on a suitable delivery route. A pulmonary delivery route can directly deliver gene vectors to the lung which is more efficient than a systemic delivery route. For gene carriers, cationic liposomes have recently emerged as leading non-viral vectors in worldwide gene therapy clinical trials. However, cytotoxic effects or apoptosis are often observed which is mostly dependent on the cationic lipid used. Therefore, an efficient and safe cationic lipid, 6-lauroxyhexyl lysinate (LHLN), previously synthesized by our group was first used to prepare cationic liposomes. Physicochemical and biological properties of LHLN-liposomes were investigated. LHLN-liposome/DNA complexes showed positive surface charge, spherical morphology, a relatively narrow particle size distribution and strong DNA binding capability. Compared with Lipofectamine2000, the new cationic liposome formulation using LHLN exhibited not only lower cytotoxicity (P < 0.05) but also similar transfection efficiency in A549 and HepG2 lung cancer cells for in vitro tests. When administered by intratracheal instillation into rat lungs for in vivo evaluation, LHLN-liposome/DNA complexes exhibited higher pulmonary gene transfection efficiency than Lipofectamine2000/DNA complexes (P < 0.05). These results suggested that LHLN-liposomes may have great potential for efficient pulmonary gene delivery.

Clinical issues and frequent questions about biotinidase deficiency

Biotinidase deficiency is a biotin-responsive, inherited neurocutaneous disorder. The disorder is readily treatable and is screened for in the newborn period. Over the years since the discovery of the disorder, many practical questions and issues have been raised as to the diagnosis, management, treatment, and newborn screening of the disorder. In this paper, many of these issues are addressed using evidence-based medicine and anecdotal experiences. If adequate answers are not known, the answers to these queries will require future investigations.

Biocompatibility analysis of chemomechanical caries removal material Papacárie on cultured fibroblasts and subcutaneous tissue

Chemomechanical caries removal allies an atraumatic technique with antimicrobiotic characteristics, minimizing painful stimuli and maximally preserving healthy dental structures. The purpose of this study was to compare the cytotoxic effects of papain-based gel (Papacarie) and another caries-removing substance, Carisolv, to a nontreatment control on cultured fibroblasts in vitro and the biocompatibility in subcutaneous tissue in vivo. The cytotoxicity analysis was performed on fibroblast cultures (NIH-3T3) after 0-, 4-, 8-, and 12-hour exposure (cell viability assay) and after 1-, 3-, 5-, and 7-day exposure (survival assay). In the in vivo study, the 2 compounds were introduced into polyethylene tubes that were implanted into subcutaneous tissues of rats. After 1, 7, 14, 30, and 60 days, tissue samples were examined histologically. Cell viability did not differ between the 2 experimental groups. The control group, however, showed significantly higher percentage viability. There were no differences in cell survival between the control and experimental groups. The histological analysis revealed a moderate inflammatory response at 2 and 7 days and a mild response at 15 days, becoming almost imperceptible by 30 and 60 days in both experimental groups. The 2 tested substances exhibited acceptable biocompatibilities and demonstrated similar responses in the in vitro cytotoxicity and in vivo implantation assay.

Mechanistic studies on the lysine-induced N-formylation of 2,5-dimethyl-p-benzoquinonediimine

2,5-Dimethyl- p-benzoquinonediimine was used as a model to study the reactivity of p-benzoquinonediimines, the first oxidation intermediates of allergenic p-amino aromatic compounds, toward lysine, as it has been suggested that this amino acid could play a key role in the induction mechanism of allergic contact dermatitis for a number of chemicals. The use of 6-[ (13)C]lysine and Nalpha-acetyl-6-[ (13)C]lysine, in association with (13)C NMR and HPLC in tandem with mass spectrometry techniques, allowed the identification of 4-amino-2,5-dimethylformanilide, 4-amino-2,5-dimethyl[ (13)C]formanilide, and the derivative containing the amino acid covalently bound at the para position. While enzymatic N-acetylation of p-phenylenediamine (PPD) has been described in the literature, in human skin for example, to our knowledge this was the first time that N-formylation of a PPD derivative induced by the reaction with an amino acid such as lysine was observed in solution, together with the formation of an adduct with the amino acid. To afford an explanation for the lysine-induced N-formylation,we undertook mechanistic studies, and they showed that 2,5-dimethyl- p-benzoquinonediimine was involved in an oxido reduction process that is capable of deaminating the alpha-NH 2 group, even when N-acetylated, and the epsilon-NH 2 groups of lysine in an oxidative way, forming the real reactive intermediates for N-formylation. This initially unexpected behavior should be considered when investigating the reactivity of such compounds with lysine-containing peptides or proteins in the context of hapten-protein binding studies.

Determination of interleukin-1α in human NCTC 2544 keratinocyte cells as a predictor of skin irritation from lysine-based surfactants

Lysine derivative surfactants are a class of amino acid-based surfactants synthesized as lecithin analogues that deserve particular attention because of their low toxicity and high biocompatibility. To complete the toxicological profile of these surfactants, IL-1 alpha production (cell-associated and release to the culture medium) was determined as an in vitro method for predicting skin irritation. In addition, an MTT assay was used as a viability marker in keratinocytes NCTC 2544. Keratinocytes are a biologically relevant target for developing in vitro techniques to assess skin irritants: moreover, they are the principal source of the proinflammatory cytokine IL-1 alpha in the epidermis. Lysine derivatives proved to be less potent in stimulating IL-1 alpha synthesis and induced a lower release of this cytokine into the culture medium when compared to the anionic surfactant sodium dodecyl sulfate. Due to their low irritancy potential, lysine-based surfactants may offer promising applications in pharmaceutical and cosmetic preparations.

Mechanistic aspects of apoptosis induction by l-lysine in both HTLV-1-positive and -negative cell lines

The retrovirus human T-cell lymphotrophic virus type-1 (HTLV-1) causes adult T-cell leukemia (ATL), which remains with no cure. This study evaluates the effects of l-lysine on proliferation and induction of apoptosis using non-cytotoxic concentrations of the test compound against HTLV-1 positive and negative malignant cell lines. The anti-proliferative effect of lysine was established and confirmed by studying the effects of the test compound on the expression of TGF mRNA expression by RT-PCR. To investigate the effect of l-lysine on the induction of apoptosis, DNA flow cytometry analyses was done and the results verified by cell death ELISA. The results indicated that a significant increase in the preG(1) phase and a decrease in the S phase of the cell cycle in all of the ATL cells tested. l-Lysine up-regulated p53, p21, and Bax protein levels and a down-regulation of Bcl-2alpha in all the cell lines tested. l-Lysine was found to exert its effect through the NF-kappaB pathway by inhibiting the p65 subunit specifically. Also l-lysine caused a decrease in the levels MMP-2 and MMP-9 as well as their enzymatic activity.

The biological properties of lysine-derived surfactants

We examine the effects of aquatic toxicity on Daphnia magna, the antimicrobial activity of new anionic lysine-derivative surfactants, and the influence of different-sized counterions associated with the surfactants. Surfactants with Tris and Lithium had less of a toxic effect on Daphnia, while all surfactants proved highly active against yeasts and the gram-negative bacteria Bordetella bronchiseptica. Counterion size was found to have no effect on aquatic toxicity or antimicrobial activity.

A diet-induced mouse model for glutaric aciduria type I

In the autosomal recessive human disease, glutaric aciduria type I (GA-1), glutaryl-CoA dehydrogenase (GCDH) deficiency disrupts the mitochondrial catabolism of lysine and tryptophan. Affected individuals accumulate glutaric acid (GA) and 3-hydroxyglutaric acid (3-OHGA) in the serum and often suffer acute striatal injury in childhood. Prior attempts to produce selective striatal vulnerability in an animal model have been unsuccessful. We hypothesized that acute striatal injury may be induced in GCDH-deficient (Gcdh-/-) mice by elevated dietary protein and lysine. Here, we show that high protein diets are lethal to 4-week-old and 8-week-old Gcdh-/- mice within 2-3 days and 7-8 days, respectively. High lysine alone resulted in vasogenic oedema and blood-brain barrier breakdown within the striatum, associated with serum and tissue GA accumulation, neuronal loss, haemorrhage, paralysis, seizures and death in 75% of 4-week-old Gcdh-/- mice after 3-12 days. In contrast, most 8-week-old Gcdh-/- mice survived on high lysine, but developed white matter lesions, reactive astrocytes and neuronal loss after 6 weeks. Thus, the Gcdh-/- mouse exposed to high protein or lysine may be a useful model of human GA-1 including developmentally dependent striatal vulnerability.

EFFECTS OF LYSINE-INDUCED ACUTE RENAL FAILURE IN DOGS

This study investigates the effects of lysine-induced acute renal failure. Female dogs received a lysine hydrochloride (lysine) of 4500 mg/kg/day (3.75 ml/kg/hr) for 3 consecutive days. The dogs were observed for clinical signs. Body weights were recorded, food consumption and water consumption calculated, and urinalysis and blood biochemistry were performed daily. Plasma samples for amino acid determinations were obtained from all dogs, which were necropsied on Day 3. Histopathological examinations were done on all test animals. Compound-related findings include the following. Blood biochemistry results showed increases in ammonia, blood urea nitrogen, blood urea nitrogen/creatinine ratio, and creatinine. Urinary changes consisted of increases in urine volume, total protein, albumin, gamma-glutamyl transpeptidase, and N-acetyl-beta-D-glucosaminidase. In addition, macroscopic findings consisted of pale, congested capsule; microscopic findings consisted of hypertrophy of proximal convoluted tubule (mainly S1 segment), and degeneration/desquamation of urinary tubule (mainly S3 segment with hyaline casts) in the kidney. From these findings, it can be concluded that lysine is nephrotoxic in dogs. Nephrotoxicity of lysine may relate to direct tubular toxicity and to tubular obstruction.

Thirteen-week oral toxicity study of L-lysine hydrochloride in rats

L-Lysine hydrochloride (Lys) is an essential amino acid in humans and animals, and it is used in animal feeds, in prevention of herpes simplex recurrence, and cereal fortification in some developing countries. This study evaluated toxicological and behavioral effects of Lys during a dosing study with male and female Sprague-Dawley rats. The amino acid was incorporated into a standard diet at doses equal to 1.25%, 2.5%, and 5.0% (w/w). A control group of rats received a standard diet. All diets were administered ad libitum for 13 consecutive weeks. To examine stability of any potential effects, the administration period was followed by a 5-week recovery period, during which only the standard diet was provided to all animals. In male and female rats in each concentration group, treatment-related changes were not observed in the clinical signs, body weights, diet consumption, water intake, ophthalmology, gross pathology, organ weights, or histology. A Lys-related drop in serum concentration and an increase in urine excretion of chlorides was a compensatory reaction to the ingested hydrochloride. No functional, biochemical, or histological changes in renal function were found. The no-observed-adverse-effect level (NOAEL) for Lys was estimated at 5.0% for both genders (male, 3.36 +/- 0.12 g/kg/day; female, 3.99 +/- 0.28 g/kg/day).

Reaction of mouse subcutaneous tissue to Carisolv--a morphologic study

This study was designed to investigate in vivo subcutaneous tissue reactions after Carisolv contact in a mouse model. Eighteen mice were implanted with two polyethylene tubes: the implant on the right side included a sponge soaked in Carisolv; the implant on the left side served as a control. Similar tissue response was displayed in both test and control groups, suggesting that Carisolv does not result in adverse effects as compared with a control. The tendency of connective tissue encapsulating the implants in both groups may result from the presence of materials that can be well-tolerated by the organism.

Galectin-3/AGE-receptor 3 knockout mice show accelerated AGE-induced glomerular injury: evidence for a protective role of galectin-3 as an AGE receptor

We previously showed that mice lacking galectin-3/AGE-receptor 3 develop accelerated diabetic glomerulopathy. To further investigate the role of galectin-3/AGE-receptor function in the pathogenesis of diabetic renal disease, galectin-3 knockout (KO) and coeval wild-type (WT) mice were injected for 3 months with 30 microg/day of N(epsilon)-carboxymethyllysine (CML)-modified or unmodified mouse serum albumin (MSA). Despite receiving equal doses of CML, KO had higher circulating and renal AGE levels and showed more marked renal functional and structural changes than WT mice, with significantly higher proteinuria, albuminuria, glomerular, and mesangial area and glomerular sclerosis index. Renal 4-hydroxy-2-nonenal content and NFkappaB activation were also more pronounced in KO-CML vs. WT-CML. Kidney mRNA levels of fibronectin, laminin, collagen IV, and TGF-beta were up-regulated, whereas those of matrix metalloproteinase-2 and -14 were down-regulated, again more markedly in KO-CML than WT-CML mice. Basal and CML-induced RAGE and 80K-H mRNA levels were higher in KO vs. WT mice. MSA injection did not produce any significant effect in both genotypes. The association of galectin-3 ablation with enhanced susceptibility to AGE-induced renal disease, increased AGE levels and signaling, and altered AGE-receptor pattern indicates that galectin-3 is operating in vivo as an AGE receptor to afford protection toward AGE-dependent tissue injury.

Comparison of different ibuprofen-amino acid compounds with respect to emulsifying and cytotoxic properties

Sodium ibuprofen (Ibu-Na) and different ibuprofen-amino acid compounds, lysinate (Ibu-Lys), arginate (Ibu-Arg) and histidinate (Ibu-His), were evaluated for emulsifying, haemolytic and cytotoxic properties. The highest reduction of surface tension was obtained with Ibu-Lys which shows good emulsifying qualities. At the same time, Ibu-Lys reveals the highest haemolytic activity and affects porcine cornea integrity. However, incorporation of Ibu-Lys into an emulsion system significantly decreases haemolysis. On the contrary Ibu-Arg, which shows a lower surface tension reduction, allows, unlike Ibu-Na and Ibu-His, for comparably stable emulsions with comparable erythrocyte damage.

Development of a Peptide Reactivity Assay for Screening Contact Allergens

Allergic contact dermatitis resulting from skin sensitization is a common occupational and environmental health problem. In recent years, the local lymph node assay (LLNA) has emerged as a practical option for assessing the skin sensitization potential of chemicals. In addition to accurate identification of skin sensitizers, the LLNA can also provide a reliable measure of relative sensitization potency; information that is pivotal in successful management of human health risks. However, even with the significant animal welfare benefits provided by the LLNA, there is still interest in the development of nonanimal test methods for skin sensitization testing. One characteristic of a chemical allergen is its ability to react with proteins prior to the induction of skin sensitization. The majority of chemical allergens is electrophilic and as such reacts with nucleophilic amino acids like cysteine or lysine. In order to determine if reactivity correlates with sensitization potential, 38 chemicals representing allergens of different potencies (weak to extreme) and nonsensitizers were evaluated for their ability to react with glutathione or three synthetic peptides containing either cysteine, lysine, or histidine. Following a 15-min reaction time for glutathione or a 24 h reaction period for the three synthetic peptides, the samples were analyzed by HPLC. UV detection was used to monitor the depletion of glutathione or the peptide following reaction. The results demonstrate that a significant correlation (Spearman correlation) exists between allergen potency and the depletion of glutathione (p = 0.001), lysine (p = 0.025), and cysteine (p = 0.020), but not histidine. The peptide with the highest sensitivity was cysteine (80.8%) whereas histidine was the least sensitive (11.5%). The data presented show that measuring peptide reactivity has utility for screening chemicals for their skin sensitization potency and thus potential for reducing our reliance on animal test methods.

The effects of a caries-removing gel (Carisolv) on FM3A cell-line in vitro

OBJECTIVES

The aim of this study was to examine the cytotoxic effects of Carisolv on mouse mammary carcinoma cell line (FM3A) at different application times.

METHODS

The FM3A cell line obtained from the European Collection of Animal Cell Cultures was used in the cell culture assays. Exponentially growing cells were seeded in 5x10(5)cells/well in 5 ml of RPMI 1640 medium supplemented with 10(%) fetal calf serum and antibiotics in each well of a six-well plate. Carisolv gel was applied onto the cell culture medium for 1, 5 and 20 min and incubated for 24 h at 37 degrees C in a humidified atmosphere of 5(%) carbon dioxide (CO(2)). After 24 h incubation, the cells were collected by trypsinisation and counted with a hemocytometer. The cytotoxicity of the Carisolv was determined by evaluation of cell growth and viability in comparison to untreated controls (cell growth=100%). For cell viability, the trypane blue exclusion assay was used. Dunnett's t-test was used for statistical analysis.

RESULTS

Cell growth was significantly reduced after 20 min application of Carisolv in comparison to the control (p < 0.001) and 1 min treatment groups (p < 0.05) No significant differences were found in cell viability between the study groups.

CONCLUSIONS

It can be concluded that prolonged application of Carisolv did not affect cell viability, but had a reducing effect on cell growth in the FM3A cell line.

Covalent bonding of lysine to EVAL membrane surface to improve survival of cultured cerebellar granule neurons

Polylysine is a commonly used coating material in the preparation of neuronal cultures. In the present study, poly (ethylene-co-vinyl alcohol) (EVAL) membranes were modified by the covalent bonding of lysine via isocyanation of surface hydroxyl groups to improve cell behavior in cultured cerebellar granule neurons from 7-day-old Wistar rats. Cell survival and death ratio were assayed by MTT reduction activity and lactate dehydrogenase release, respectively. Cell morphology and neurite growth were observed by a scanning electron microscope. It was found that immobilizing lysine onto the EVAL membranes could improve neuronal MTT reduction activity and delay the death rate of neurons. In addition, neurons seeded on the lysine-immobilized EVAL membrane were able to regenerate with the formation of an extensive neuritic network, indicating that the surface modification on the EVAL membrane should be useful for culturing of neurons. Furthermore, the influence exerted by the modification of different amino acids (glycine, arginine and ornithine) onto the EVAL membranes on the neuronal behavior were investigated. We found that the effect of the terminal primary amine of the side chain of the basic amino acids on the neuronal behavior should be taken into account because the immobilized glycine molecules did not improve neuronal cultures. In order to interpret the phenomenon further, in the surface modification process, both the two amino groups of lysine were designed to react with the EVAL membrane surface to form a cyclic structure. On such a surface, neuronal MTT reduction activity was decreased and neuronal death was not delayed. The result shows that the lysine molecules immobilized on the EVAL membrane surface can mediate cellular response to promote neuronal cell survival and guidance of neuritic processes, indicating a delicate interaction of neuron with lysine molecules on the EVAL membrane surface.

Reactions in the oral mucous membrane after exposure to Carisolv--combined results from a clinical screening test in humans and an experimental study in rats

OBJECTIVE

To evaluate reactions in the oral mucosa after direct contact with Carisolv.

SETTING

The Faculty of Odontology in Göteborg, Sweden.

SUBJECTS

34 healthy persons for a clinical screening test and 35 Sprague Dawley rats for a histological study.

DESIGN

Mixed Carisolv or 0.5 % NaOCl were soaked in paper and applied to either side of the medial frenula of the lower lip of 34 persons. The solutions were left on the oral mucosa for three minutes. Inspection was made and photographs were taken immediately after exposure and also after 1 hour, 24 hours, and 72 hours. Mixed Carisolv was applied in a similar manner as described above to 35 adult Sprague Dawley rats. The animals were killed and biopsies were taken immediately after Carisolv exposure and also after 1 hour, 24 hours, and 48 hours. The biopsies were sectioned and prepared for histomorphometrical evaluation in light microscopy where cells were counted on regions from the epithelium layer deeper into the mucous membrane.

RESULTS

Some adverse reactions were detected on the oral mucosa of humans up to 24 hours after Carisolv exposure for 3 minutes. The detected inflammatory reactions were slight and no patient felt any discomfort. The results of the histological study on rat did not show any statistically significant increase of the number of cells at any time after Carisolv exposure.

CONCLUSIONS

If the oral mucosa gets in direct contact with Carisolv for 3 minutes no or only a weak inflammatory response may be expected.

A randomised, controlled and blinded histological and immunohistochemical investigation of Carisolv on pulp tissue

OBJECTIVES

This investigation was undertaken to test the hypothesis that Carisolv would show the same safety profile as physiologic saline when in direct contact with pulp tissue for 30 min. Furthermore, the sensory nerve fibre reaction in response to the injury was evaluated.

METHODS

Incisors and molars in 40 Sprague-Dawley rats were opened and the pulp tissue randomly exposed to either Carisolv or NaCl for 30 min. Observation periods ranged from I day to I week.

RESULTS

Light microscopic examination showed an almost identical cellular response in both test teeth and controls, which consisted of a localised inflammation represented predominantly by macrophages. Immunohistochemistry revealed an accumulation of beaded CGRP-immunoreactive fibres in immediate vicinity of the lesion, suggesting that the nerves had emitted small sprouts. Some fibres at this location were SP-positive, but very few, or no nerve fibres, displayed NPY-immunoreactivity. This innervation pattern was seen in both test and controls in similar distribution and at similar intensity.

CONCLUSIONS

Results obtained in this study suggests the hypothesis to be valid, i.e. Carisolv does not seem to add appreciable adverse effects over and beyond what is caused by the experimental procedures. Furthermore, Carisolv does not seem to influence the distribution or neuropeptide expression of sensory nerve fibres in the pulp.

Histocytological evaluation of the reaction of rat pulp tissue to Carisolv

OBJECTIVES

Carisolv is a viscous substance for the chemo-mechanical removal of caries. The aim of this study was to examine the tissue reactions of pulp and dentin tissue to Carisolv in vivo.

METHODS

In 48 caries-free molars (24 Wistar rats, age: 3 months) an occlusal cavity was prepared. The roofs of the pulp chambers were perforated with a sharp probe and Carisolv solution was placed onto the exposed pulp of 24 molars for 1, 10 and 20 min. Twenty-four contralateral molars served as controls and were coated with an inert liquid containing isotonic saline solution, carmellose and erythrosin.

RESULTS

After a contact period of 10 and 20 min in the experimental group, pulpal destruction of intercellular substance and cells including odontoblasts was observed up to a depth of 150 microm, in addition to the mechanical damage by perforation (e.g. dentin particles). The pulpal and predentin fibrils as well as the dentin fibrils appeared to be intact and did not differ from the controls. After a contact time of 1 min a weaker damage of pulp cells and odontoblasts, as well as intact fibrils in pulp, predentin and dentin could be observed.

CONCLUSIONS

Radicals of Carisolv (OH- and OCI-) cause alkaline hydrolysis of cellular components but do not decompose collagenous tissue components.

pH-sensitive cationic polymer gene delivery vehicle: N-Ac-poly(L-histidine)-graft-poly(L-lysine) comb shaped polymer

Advancing biotechnology spurs the development of new pharmaceutically engineered gene delivery vehicles. Poly(L-histidine) ¿PLH¿ has been shown to induce membrane fusion at endosomal pH values, whereas PLL has a well documented efficacy in polyplex formation. Therefore, N-Ac-poly(L-histidine)-graft-poly(L-lysine) ¿PLH-g-PLL¿ was synthesized by grafting poly(L-histidine) to poly(L-lysine) ¿PLL¿. PLH-g-PLL formed polyplex particles by electrostatic interactions with plasmid DNA ¿pDNA¿. The mean particle size of the polyplexes was in the range of 117 +/- 6 nm to 306 +/- 77 nm. PLH-g-PLL gene carrier demonstrated higher transfection efficacy in 293T cells than PLL at all equivalent weight ratios with pDNA. The inclusion of chloroquine as an endosomolytic agent enhanced transfection for both PLL and PLH-g-PLL gene carriers. PLH-g-PLL enhanced beta-galactosidase expression compared to PLL, but still increased in efficacy when chloroquine was included.

Toxicity of platinum(II) amino acid (N,O) complexes parallels their binding to DNA as measured in a new solid phase assay involving a fluorescent HMG1 protein construct readout

The compound [Pt(lysine)Cl2] (Kplatin) was previously identified in a study of platinum amino acid complexes as a potential antitumor drug candidate. The DNA binding properties, high mobility group (HMG)-domain protein affinity for the platinated DNA, and cytotoxicity against HeLa cells of Kplatin and three related (N,O) chelated platinum(II) amino acid complexes, [Pt(arginine)Cl2] (Rplatin), K[Pt(Nepsilon-acetyllysine)Cl2] (NacKplatin), and K[Pt(norleucine)Cl2] (Norplatin), are reported. The four complexes have identical PtCl2(N,O) coordination environments. A new solid phase screening methodology was devised in which platinated DNA probes are covalently attached to a nylon support and tested for their ability to bind a fluorescently labeled HMG-domain protein. The fluorescent HMG-domain protein was generated by expressing a fusion of the green fluorescent protein (GFP) with recombinant rat HMG1. Binding revealed by the solid phase method correlated well with the results of gel mobility shift and HeLa cytotoxicity assays. These results suggest that the net charge on the complex, rather than the nature of the side chain, is the most important factor underlying the DNA binding properties and toxicity of amino acid (N,O) chelated platinum complexes. This property explains why Kplatin was previously selected from the pool of platinum amino acid complexes based on the ability of its DNA adducts to bind HMG1.

The metabolic roles, pharmacology, and toxicology of lysine

L-lysine monohydrochloride (LMH) is widely available to the public as a nonprescription oral supplement. Most of the pharmaceutical-grade product is used as a suppressant of recurrent herpes simplex infections. Recent publications indicate the possibility of other therapeutic uses, e.g., in cardiovascular disease and osteoporosis. These and other potential applications are surveyed and evaluated in this review with suggestions for further study. Data on toxicity are reviewed and recommendations made regarding safety of chronic dosage levels.

Epileptogenic activity induced by combined treatment with antiinflammatory drugs and enoxacin and its inhibition by a calcium antagonist, nicardipine

Epileptogenic activity induced by combined treatment with antiinflammatory drugs and enoxacin was investigated in chronic electrode-implanted rats. Ferubinac ethyl and aspirin DL-lysine showed a spike and wave complex in EEG without showing remarkable behavioral changes when they were injected intraventricularly, although a relatively high dose was needed. Enoxacin, on the other hand, elicited potent epileptogenic activity characterized by uninterrupted high voltage spike and wave complex at doses of 50 and 100 micrograms. At the same time, rats showed hyperactivity, jumping and violent convulsion. Combined treatment with enoxacin (p.o.) and ferubinac ethyl (i.v.) caused potent epileptogenic activity characterized by uninterrupted burst of high voltage spike and wave complex. Behaviorally, animals showed forelimb clonus, head nodding and generalized convulsion. High voltage spike and wave complex was also observed after combined treatment with enoxacin (i. vent.) and ferubinac ethyl (i.v. or i. vent.) in association with hyperactivity and jumping and violent convulsion. Nicardipine remarkably inhibited epileptic seizures induced by combined treatment with enoxacin (p.o.) and ferubinac ethyl (i.v.). It is concluded that simultaneous treatment with enoxacin and ferubinac ethyl produced epileptogenic activity when injected intraventricularly, and nicardipine inhibited convulsions induced by combined use of enoxacin (p.o.) and ferubinac ethyl (i.v.).

The topographical organization of descending projections from the central nucleus of the inferior colliculus in guinea pig

We describe the descending projections from the central nucleus of the inferior colliculus (CNIC) in guinea pig. Focal injections of the tracer biocytin, made in physiologically defined frequency regions of the CNIC, labelled laminated axonal terminal fields in the ipsilateral dorsal nucleus of the lateral lemniscus, and bilaterally in the ventral nucleus of the trapezoid body and the dorsal cochlear nucleus. Labelling was also present in the rostral periolivary nucleus, but we could not distinguish a clear border between the terminal fields in this nucleus and those in the ventral nucleus of the trapezoid body. Labelling observed in the ventral nucleus of the lateral lemniscus, and to a lesser extent in the dorsal nucleus of the lateral lemniscus, was accompanied by retrogradely labelled somata and therefore we cannot conclude unequivocally that the CNIC projects to these lemniscal nuclei. Where the labelling was ordered topographically, its position varied as a function of the best frequency at the injection site. High-frequency regions in the CNIC project to the medial parts of the ventral nucleus of the trapezoid body and dorsal cochlear nucleus, while low-frequency regions in the CNIC project to the lateral parts of the ventral nucleus of the trapezoid body and dorsal cochlear nucleus. Additional axonal labelling with terminal boutons, but with no apparent topographical arrangement, was present in the ipsilateral horizontal cell group, sagulum, and also bilaterally in the superficial granule cell layer of the ventral cochlear nucleus and layer 2 of the dorsal cochlear nucleus. Our findings are consistent with the existence of tonotopically organised feedback projections from the CNIC to the brainstem nuclei that project to it.

Inhibition of human immunodeficiency virus type 1 infectivity by a new amine bellenamine

Bellenamine, (R)-3,6-diamino-N-(aminomethyl)hexanamide (molecular weight 174), produced by Streptomyces nashvillensis, which has been reported to have weak antibacterial activity and to slightly enhance the immune response, showed potent activity against human immunodeficiency virus type 1 (HIV-1). Its mode of action was investigated. Bellenamine inhibited de novo infection of human T cells with HIV-1, at a 50% effective concentration (EC50) of 0.62 micrograms/ml (3.6 microM). Its 50% cytotoxic concentration (CC50) was over 2000 micrograms/ml (11.5 mM) and thus its cytotoxicity was quite low. When HIV-1-infected cells were treated with bellenamine or glycosylation inhibitors, they produced virus with reduced infectivity, and thus bellenamine inhibited the secondary spread of HIV-1 in vitro similarly to glycosylation inhibitors. However, bellenamine did not change the apparent molecular weights of env or gag proteins, unlike glycosylation inhibitors. Bellenamine showed no significant activity against virus adsorption, reverse transcriptase, viral protease or the glycosylation process. The antiviral mechanism of bellenamine remains to be examined further.

Preliminary studies of the toxic effects of non-ionic surfactants derived from lysine

The toxic effects of new synthetic monodisperse non-ionic long-chain N alpha, N epsilon-diacyl lysine polyoxyethylene glycol amide compounds with a structural resemblance to natural lecithin phospholipids were studied by the haemolytic method and the test of the chorioallantoic membrane of the hen's egg (HET-CAM). The following compounds were tested: symmetrical N alpha,N epsilon-diacyl lysine homologues (N alpha,N epsilon-dihexanoyl, N alpha,N epsilon-dioctanoyl and N alpha,N epsilon-didecanoyl lysine) with one methyl ether polyoxyethylene glycol chain of different oxyethylene units (dioxyethylene glycol, tetraoxyethylene glycol and hexaoxyethylene glycol) as headgroup; symmetrical N alpha,N epsilon-diacyl lysine homologues with two methyl ether dioxyethylene glycol chains and the asymmetrical N alpha-butanoyl, N epsilon-dodecyl lysine with two hydrophilic methyl ether dioxyethylene glycol chains as headgroup. A commercial (polydisperse) oleoyl polyoxyethylene glycol diethanolamide with an average of eight units of ethylene oxide was used as control. All the synthesized tested compounds appeared to be less haemolytic and less irritant than the control. The synthesized products were studied with regard to their hydrophobic and hydrophilic chains in order to evaluate the influence of their structure on their haemolytic and irritative action. The results of this study show that the acyl chain distribution of these compounds greatly influence toxic effects: the asymmetrical compound N alpha-butanoyl,N epsilon-dodecyl lysine-bis[methyl ether diethylene glycol]amide was found to be the most haemolytic and irritating compound. Among the symmetrical homologues, the shortest-chain compounds N alpha,N epsilon-dihexanoyl lysine methyl ether polyoxyethylene glycol amides present the least haemolytic and irritating activity, independently of the number and length of the hydrophilic methyl ether polyoxyethylene glycol chains. Taking into account their surface activity properties and their less haemolytic and irritant action, the compound N alpha,N epsilon-dioctanoyl lysine-bis[methyl ether diethylene glycol]amide would be the most suitable for practical purposes.

Non-enzymatic glycosylation of the dipeptide L-carnosine, a potential anti-protein-cross-linking agent

The dipeptide carnosine (beta-alanyl-L-histidine) was readily glycosylated non-enzymatically upon incubation with the sugars glucose, galactose, deoxyribose and the triose dihydroxyacetone. Carnosine inhibited glycation of actyl-Lys-His-amide by dihydroxyacetone and it protected alpha-crystallin, superoxide dismutase and catalise against glycation and cross-linking mediated by ribose, deoxyribose, dihydroxyacetone, dihydroxyacetone phosphate and fructose. Unlike certain glycated amino acids, glycated carnosine was non-mutagenic. The potential biological and therapeutic significance of these observations are discussed.

Gastrointestinal blood loss induced by three different non-steroidal anti-inflammatory drugs

A clinical study was performed on 18 healthy volunteers to compare the gastrointestinal daily blood loss induced by oral intake of three different non-steroidal anti-inflammatory drugs, lysine clonixinate (CAS 55837-30-4), ibuprofen (CAS 15687-27-1) and acetylsalicylic acid (CAS 50-78-2 ASA). For quantitative determination of gastrointestinal blood loss, autologous erythrocytes were radiolabelled in vitro with 51Cr and reinfused at study start. The amount of radioactivity excreted in faeces was measured during a placebo baseline phase of three days, a treatment phase of five days with thrice daily dosing of ASA, ibuprofen or lysine clonixinate and a subsequent wash-out phase of five days. The highest increase of mean daily blood loss over baseline was observed after treatment with ASA (+ 1.66 ml/d versus baseline). Treatment with ibuprofen led to an increase of mean daily blood loss by + 0.52 ml/d. During treatment with lysine clonixinate the mean increase of daily blood loss was +0.32 ml/d versus baseline. In the ibuprofen and lysine clonixinate treatment groups the values of mean daily blood loss decreased during the wash-out phase with respect to the verum phase, whereas the mean daily blood loss during the wash-out phase after treatment with ASA even increased in comparison to the verum phase (mean daily blood loss: +2.07 ml/d versus baseline.

The tonotopic map in the embryonic chicken cochlea

The purpose of the present study was to determine the tonotopic map in the chicken cochlea at 19 days of incubation (E19) by obtaining characteristic frequencies (CFs) for primary afferents, labeling the characterized neurons, and documenting their projections to the papilla. The lowest and highest CFs recorded were 188 and 1623 Hz respectively. The embryonic tonotopic map coincided with maps reported for post-hatch chicks. There were no evidence that neurons selective to low frequencies project inappropriately to more basal locations of the embryonic papilla. Linear regression was used to estimate the frequency gradient (b = 0.037 +/- 0.012 In Hz/% [b +/- SEb]) and intercept (In C, where C = 111 Hz) of the semilog plot of frequency versus cochlear position (in % distance from apex). From these estimates the octave distribution was calculated to be 18.7%/octave or 0.58 mm/octave. These quantities were not significantly different from those found in post hatch chickens. We conclude that the tonotopic map of the avian cochlea for CFs between 100 and 1700 Hz is stable and relatively mature from age E19 to post-hatch day 21 (P21). The most striking sign of immaturity in the E19 embryo is the limited range of high CFs. We offer the hypothesis that, between the ages of E19 and P21, improvements in middle ear admittance alone or in combination with functional maturation of the cochlear base may be the principal factors responsible for the appearance of adult-like high CF limits and not an apically shifting tonotopic map.

Effects of ibuprofen lysinate and acetylsalicylic acid on gastric and duodenal mucosa. Randomized single-blind placebo-controlled endoscopic study in healthy volunteers

Acetylsalicylic acid (ASA, CAS 50-78-2) and ibuprofen (IB) are commonly used over-the-counter drugs for short-term treatment of pain of different origin. Ibuprofen lysinate (IBL, CAS 57469-76-8) is a water soluble form of ibuprofen for rapid absorption. This single blind, randomized, controlled study compared the incidence and severity of irritation of gastric and duodenal mucosa in normal healthy subjects (n = 45) following administration of IBL (Dolormin) 800 mg/d, ASA 2000 mg/d or placebo for 3 consecutive days. Gastric and duodenal mucosal injury were assessed endoscopically using a severity scale of 0-4 for mucosal erosions and mucosal hemorrhages. Mean gastric hemorrhage and erosion scores for ASA and IBL were significantly higher than those for placebo. In addition, ASA was found to be significantly more irritating to gastric mucosa than IBL, in both the incidence and severity of gastric erosions. No duodenal hemorrhages were detected in this study. The incidence of duodenal erosions was significantly higher in the ASA group (64%) than in both the IBL (6%) and placebo groups (0%) which were not significantly different. Only one subject (in the placebo group) reported an adverse experience (mild headache) during the study. The data suggest that both active treatments are more injurious to the gastric mucosa than placebo when given for 3 days to normal healthy volunteers, but that IBL 800 mg/d is significantly less injurious to the gastric and duodenal mucosa than ASA 2000 mg/d.

In vitro photodynamic effects of lysyl chlorin p6: cell survival, localization and ultrastructural changes

The in vitro cell survival, localization and ultrastructural changes following irradiation were examined in 9L glioma cells sensitized with a new photosensitizer, lysyl chlorin p6 (LCP). In clonogenic assays, LCP was 10-100-fold more phototoxic than photofrin II on a microgram/mL basis. Lysyl chlorin p6 uptake was blocked when cells were incubated at 2 degrees C. In view of the chemical properties of LCP, this finding indicates that uptake probably occurred through the endocytic pathway. Fluorescence studies showed LCP localized in a region of the endocytic compartment similar in size, shape and distribution to that labeled by lucifer yellow CH (LY), as well as localizing diffusely throughout the perinuclear cytoplasm. Cells stained with both LY and LCP, however, had distinctly separate regions of staining. Lysyl chlorin p6 localization differed from that of fluorescent probes labeling the mitochondria, Golgi apparatus and endoplasmic reticulum. Ultrastructural changes at both 2 and 30 min after laser irradiation were similar. Mitochondria were often condensed or swollen and also had constrictions and cytoplasmic invaginations. The Golgi apparatus, perinuclear space and rough endoplasmic reticulum (RER) were dilated. These data demonstrate that LCP localizes in a portion of the endosomal compartment, but that morphologic damage initially occurs in the mitochondria, Golgi apparatus and RER.

[Experimental data for evaluation of biological effect during exposure to chemical and biological factors]

Joint effects of lysin, eprin and formaldehyde in acute and subacute experiments were investigated. As shown, this effect can be evaluated as a partial summing with coefficient 1.84.