Reactions of e(-)(aq), CO(2)(*)(-), HO(*), O(2)(*)(-) and O(2)((1)delta(g)) with a dendro[60]fullerene and C(60)[C(COOH)(2)](n) (n = 2-6)

Using pulse radiolysis and laser flash photolysis, we have investigated the reactions of the deleterious species, e(-)(aq), HO&z.rad;, O(2)(*)(-) and O(2)((1)Delta(g)) with 10 water-soluble cyclopropyl-fused C(60) derivatives including a mono-adduct dendro[60]fullerene (d) and C(60) derivatives based on C(60)[C(COOH)(2)](n=2-6), some of which are known to be neuroprotective in vivo. The rate constants for reactions of e(-)(aq) and HO&z.rad; lie in the range 0.5-3.3 x 10(10) M(-1) s(-1). The d and bis-adduct monoanion radicals display sharp absorption peaks around 1000 nm (epsilon = 7 000-11 500 M(-1) cm(-1)); the anions of the tris-, tetra-, and penta-adduct derivatives have broader, weaker absorptions. The monohydroxylated radicals have their most intense absorption maxima around 390-440 nm (epsilon = 1000-3000 M(-1) cm(-1)). The anion and hydroxylated radical absorption spectra display a blue-shift as the number of addends increases. The radical anions react with oxygen (k approximately 10(7)-10(9) M(-1) s(-1)). The reaction of O(2)(*)(-) with the C(60) derivatives does not occur via an electron transfer. The rate constants for singlet oxygen reaction with the dendrofullerene and eee-derivative in D(2)O at pH 7.4 are k approximately 7 x 10(7) and approximately 2 x 10(7) M(-1) s(-1) respectively, in contrast to approximately 1.2 x 10(5) M(-1) s(-1) for the reaction with C(60) in C(6)D(6). The large acceleration of the rates for electron reduction and singlet oxygen reactions in water is due to a solvophobic process.     

Structure of the O-polysaccharide and serological cross-reactivity of the lipopolysaccharide of Providencia alcalifaciens O32 containing N-acetylisomuramic acid

The O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Providencia alcalifaciens O32 and studied by sugar and methylation analyses, solvolysis with triflic acid, 1H and 13C NMR spectroscopy, including two-dimensional 1H,1H COSY, TOCSY, ROESY, H-detected 1H,13C HSQC and HMBC experiments. It was found that the polysaccharide has a branched tetrasaccharide repeating unit containing 2-acetamido-3-O-[(S)-1-carboxyethyl]-2-deoxy-D-glucose (D-GlcNAc3Slac, N-acetylisomuramic acid) with the following structure: [STRUCTURE: SEE TEXT]. Serological studies with O-antisera showed antigenic relationships between P. alcalifaciens O32 and O29 as well as several other Providencia and Proteus strains sharing putative epitopes on the O-polysaccharides.     

Luminal flow regulates NO and O2(-) along the nephron

Urinary flow is not constant but in fact highly variable, altering the mechanical forces (shear stress, stretch, and pressure) exerted on the epithelial cells of the nephron as well as solute delivery. Nitric oxide (NO) and superoxide (O(2)(-)) play important roles in various processes within the kidney. Reductions in NO and increases in O(2)(-) lead to abnormal NaCl and water absorption and hypertension. In the last few years, luminal flow has been shown to be a regulator of NO and O(2)(-) production along the nephron. Increases in luminal flow enhance fluid, Na, and bicarbonate transport in the proximal tubule. However, we know of no reports directly addressing flow regulation of NO and O(2)(-) in this segment. In the thick ascending limb, flow-stimulated NO and O(2)(-) formation has been extensively studied. Luminal flow stimulates NO production by nitric oxide synthase type 3 and its translocation to the apical membrane in medullary thick ascending limbs. These effects are mediated by flow-induced shear stress. In contrast, flow-induced stretch and NaCl delivery stimulate O(2)(-) production by NADPH oxidase in this segment. The interaction between flow-induced NO and O(2)(-) is complex and involves more than one simply scavenging the other. Flow-induced NO prevents flow from increasing O(2)(-) production via cGMP-dependent protein kinase in thick ascending limbs. In macula densa cells, shear stress increases NO production and this requires that the primary cilia be intact. The role of luminal flow in NO and O(2)(-) production in the distal tubule is not known. In cultured inner medullary collecting duct cells, shear stress enhances nitrite accumulation, a measure of NO production. Although much progress has been made on this subject in the last few years, there are still many unanswered questions.     

Production of active oxygen species (1O2 and O2-.) by psoralens and ultraviolet radiation (320-400 nm)

Furocoumarins (psoralens) are potent skin photosensitizing agents that are used in combination with long-wavelength ultraviolet radiation (320-400 nm) in the treatment of psoriasis and other skin diseases. Twelve linear and angular psoralens, capable of forming monofunctional and bifunctional adducts with DNA, were examined with a view to elucidate the role of 1O2 and O2-. in evoking skin photosensitization reactions and skin carcinogenesis. The results showed that both linear psoralens (capable of forming interstrand cross-links) and isopsoralens (angular, monofunctional type) and 3-carbethoxypsoralen (a linear and monofunctional type) produced 1O2 and O2-., although at varying degrees. Psoralen and 3-carbethoxypsoralen produced 1O2 greater than isopsoralens (angelicins). However, nonphotosensitizing angelicin, 5-methylangelicin, and 4,8-dimethyl-5'-carboxypsoralen produced 1O2 greater than 8-methoxypsoralen and 5-methoxypsoralen. The three monofunctional angelicin derivatives (isopsoralens) produced more O2-. than 8-methoxypsoralen, 5-methoxypsoralen, and 3,4'-dimethyl-8-methoxypsoralen. 3-Carbethoxypsoralen, a potent generator of 1O2 and a moderate producer of O2-., was highly photolabile. Until recently, skin photosensitization reactions (erythema, edema, damage to DNA or the membrane of cutaneous cells, the inhibition of scheduled DNA synthesis and skin carcinogenesis, etc.) were believed to involve photocyclo-addition of psoralens to DNA mediated by a type-I or anoxic reaction (a sensitizer-substrate interaction through the transfer of hydrogen atoms or electrons, but no direct involvement of molecular oxygen). Oxygen-dependent sensitized photodynamic reactions of type-II, involving the production of reactive oxygen (1O2 and O2-.), were believed not to mediate psoralen photosensitization reactions. We suggest that 1O2 and O2-. may also participate in skin photosensitization and cell membrane-damaging reactions. The fact that certain monofunctional isopsoralens produce 1O2 and O2-. at rates comparable to or better than bifunctional psoralens suggests that these reactive moieties of oxygen could play a major role in explaining their recently observed carcinogenic property and cell membrane-damaging reactions (e.g., edema or inflammation, etc.).     

Mixed ligand complexes of platinum(II) and palladium(II) with cytokinin-derived compounds Bohemine and Olomoucine: X-ray structure of [Pt(BohH+-N7)Cl(3)].9/5H2O [Boh=6-(benzylamino)-2-[(3-(hydroxypropyl)-amino]-9-isopropylpurine,Bohemine

The new square-planar Pt(II) and Pd(II) complexes with cytokinin-derived compounds Bohemine and Olomoucine, having the formulae [Pt(BohH(+))Cl(3)].H(2)O (1), [Pt(Boh)(2)Cl(2)].3H(2)O (2), [Pt(Boh-H)Cl(H(2)O)(2)].H(2)O (3), [Pt(OloH(+))Cl(3)].H(2)O (4), [Pd(BohH(+))Cl(3)].H(2)O (5), [Pd(Boh)Cl(2)(H(2)O)] (6), [Pd(Boh-H)Cl(H(2)O)].EtOH (7) and [Pd(OloH(+))Cl(3)].H(2)O (8), where Boh=6-(benzylamino)-2-[(3-(hydroxypropyl)amino]-9-isopropylpurine and Olo=6-(benzylamino)-2-[(2-(hydroxyethyl)amino]-9-methylpurine, have been synthesized. The complexes have been characterized by elemental analyses, IR, FAB+ mass, 1H, 13C and 195Pt NMR spectra, and conductivity data. The molecular structure of the complex [Pt(BohH(+)-N7)Cl(3)].9/5H(2)O has been determined by an X-ray diffraction study. Results from physical studies show that both Bohemine and Olomoucine are coordinated to transition metals through the N(7) atom of purine ring in all the complexes. The prepared compounds have been tested in vitro for their possible cytotoxic activity against G-361 (human malignant melanoma), HOS (human osteogenic sarcoma), K-562 (human chronic myelogenous leukemia) and MCF-7 (human breast adenocarcinoma) cell lines and IC(50) values have been also determined for all the complexes. IC(50) values estimated for the Pt(II)-Bohemine complexes (2.1-16 microM) allow us to conclude that they could find utilization in antineoplastic therapy. Thus, from a pharmacological point of view, Pt(II) complexes of Bohemine may represent compounds for a new class of antitumor drugs.     

Phospholipids in chromatin: incorporation of [32P]O4(2-) in different subcellular fractions of hepatocytes

Nuclear, chromatin and microsomal fractions were isolated from hepatocytes prepared from rats injected with [32P]O4(2-) and killed subsequently at times between 1 and 48 h. Specific activities of the total phospholipids (PL) were determined for each subcellular fraction. The major points noted were the initial specific activity of the chromatin PL was half that of both nuclear and microsomal PL at 1 h; the first peak of labelling occurred at 6 h in both nuclear and microsomal PL, but was 3 h later (9h) in the chromatin PL; and a second peak of labelling occurred in the chromatin and microsomal PL, but not in those of the nuclei. On fractionation of the PL, the major and most metabolically active components were phosphatidylcholine + phosphatidylethanolamine, whilst sphingomyelin accounted for only about 8 per cent of the total PL. The chromatin and microsomal fractions were somewhat similar in their labelling patterns though with a delayed peaking of activity in the chromatin. This is indicative of a synthesis and transport of PL from the microsomes to the chromatin.     

Characterisation of a new chimeric ligand for galanin receptors: galanin(1-13)-[D-Trp(32)]-neuropeptide Y(25-36)amide

In this work, we studied a novel chimeric peptide, M242, galanin(1-13)-[D-Trp(32)]-neuropeptide Y(25-36)amide, and examined its properties in comparison with its parent peptide, M32, galanin(1-13)-neuropeptide Y(25-36)amide, a previously known high-affinity ligand for galanin receptors, and galanin itself. Binding assays performed in Bowes cells known to express human galanin receptor type 1 (hGalR1) and in Chinese hamster ovary cells overexpressing human galanin receptor type 2 (hGalR2) revealed that all three ligands had comparable affinities: at hGalR1<1 nM and at hGalR2<10 nM. However, in rat hippocampal membranes M242 had a 24-fold lower affinity than galanin (9.4 vs. 0.4 nM) and 134-fold lower affinity than M32 (9.4 vs. 0.07 nM). In the same tissue, we also examined the effects of these peptides on adenylate cyclase activity. M32 showed a weak antagonistic behaviour but M242 acted as a potent biphasic regulator of adenylate cyclase. In conclusion, we present and characterise a new peptide M242, which could be a useful tool in studies of galaninergic signalling.     

中国北亚热带油橄榄(城固32)开花生物学特性研究

为研究北亚热带内陆地区油橄榄（Olea europaea L.）开花物候、开花样式及花器官特征,探讨其有性繁殖系统的特点。试验对西秦岭南坡地区油橄榄（城固32）的开花生物学进行研究,统计开花进程,雄花和两性花在花序上的着生位置和数量,测定雄花和两性花形态指标并切片观察,电镜扫描分析雄花与两性花花粉粒。结果表明：（1）在北亚热带北缘内陆气候条件下油橄榄花期集中在5月,单株花期15~20 d,盛花期持续4~6 d;（2）油橄榄具有雄全同株的性系统且花器官较小,雄花及两性花都具有正常发育的雄蕊。通过制作石蜡切片观察,发现两性花的雌蕊正常发育,而雄花只有较小的子房和败育的柱头;（3）雌蕊是两种花型花器官生物量差异的主要部位,两性花雌蕊的生物量明显比雄花大（P<0.01）,树体分化出雄花投入的资源更少;（4）雄花与两性花在花粉量、花粉粒大小上差异不显著,在着生位置上,花序轴顶花全部为两性花,雄花出现在花序轴的中部和基部的几率分别是21.13%和30.77%。油橄榄品种城固32具有典型的雄全同株现象,雄花更倾向于在花序上出现的位置在行使它雄性功能方面并无优势可言,而且雄花花粉粒在数量、活力方面也没有优势,但是雄花的出现增加了花粉数量和P/O值,提高了植株的雄性适合度,雄花的出现也降低了两性花落花导致的树体资源浪费,保障其在资源有限的环境中能够繁殖最大化。     

Endogenous 5-methylcytosine protects neighboring guanines from N7 and O6-methylation and O6-pyridyloxobutylation by the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone

All CG dinucleotides along exons 5-8 of the p53 tumor suppressor gene contain endogenous 5-methylcytosine (MeC). These same sites (e.g., codons 157, 158, 245, 248, and 273) are mutational hot spots in smoking-induced lung cancer. Several groups used the UvrABC endonuclease incision assay to demonstrate that methylated CG dinucleotides of the p53 gene are the preferred binding sites for the diol epoxides of bay region polycyclic aromatic hydrocarbons (PAH). In contrast, effects of endogenous cytosine methylation on the distribution of DNA lesions induced by tobacco-specific nitrosamines, e.g., 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), have not been elucidated. In the work presented here, a stable isotope labeling HPLC-ESI-MS/MS approach was employed to analyze the reactivity of the N7 and O6 positions of guanines within hemimethylated and fully methylated CG dinucleotides toward NNK-derived methylating and pyridyloxobutylating species. 15N3-labeled guanine bases were placed within synthetic DNA sequences representing endogenously methylated p53 codons 154, 157, and 248, followed by treatment with acetylated precursors to NNK diazohydroxides. HPLC-ESI-MS/MS analysis was used to determine the relative yields of N7- and O6-guanine adducts at the 15N3-labeled position. In all cases, the presence of MeC inhibited the formation of N7-methylguanine, O6-methylguanine, and O6-pyridyloxobutylguanine at a neighboring G, with the greatest decrease observed in fully methylated dinucleotides and at guanines preceded by MeC. Furthermore, the O6-Me-dG/N7-Me-G molar ratios were decreased in the presence of the 5'-neighboring MeC, suggesting that the observed decline in O6-alkylguanine adduct yields is, at least partially, a result of an altered reactivity pattern in methylated CG dinucleotides. These results indicate that, unlike N2-guanine adducts of PAH diol epoxides, NNK-induced N7- and O6-alkylguanine adducts are not preferentially formed at the endogenously methylated CG sites within the p53 tumor suppressor gene.     

Genetic Characterization and Physiological Role of Endopeptidase O from Lactobacillus helveticus CNRZ32

A previously identified insert expressing an endopeptidase from a Lactobacillus helveticus CNRZ32 genomic library was characterized. Nucleotide sequence analysis revealed an open reading frame of 1,941 bp encoding a putative protein of 71.2 kDa which contained a zinc-protease motif. Protein homology searches revealed that this enzyme has 40% similarity with endopeptidase O (PepO) from Lactococcus lactis P8-2-47. Northern hybridization revealed that pepO is monocistronic and is expressed throughout the growth phase. CNRZ32 derivatives lacking PepO activity were constructed via gene replacement. Enzyme assays revealed that the PepO mutant had significantly reduced endopeptidase activity when compared to CNRZ32 with two of the three substrates examined. Growth studies indicated that PepO has no detectable effect on growth rate or acid production by Lactobacillus helveticus CNRZ32 in amino acid defined or skim milk medium.     

Mechanism of the pyrophosphate migration in the enzymatic cyclization of geranyl and linalyl pyrophosphates to (+)- and (-)-bornyl pyrophosphates

Soluble enzymes from sage (Salvia officinalis) and tansy (Tanacetum vulgare), which catalyze the cyclization of geranyl pyrophosphate and the presumptive intermediate linalyl pyrophosphate to the (+) and (-) enantiomers, respectively, of 2-bornyl pyrophosphate, were employed to evaluate mechanistic alternatives for the pyrophosphate migration in monoterpene cyclization reactions. Separate incubation of [1-3H2,alpha-32P]- and [1-3H2,beta- 32P]geranyl and (+/-)-linalyl pyrophosphates with partially purified preparations of each enantiomer-generating cyclase gave [3H, 32P]bornyl pyrophosphates, which were selectively hydrolyzed to the corresponding bornyl phosphates. Measurement of 3H:32P ratios of these monophosphate esters established that two ends of the pyrophosphate moiety retained their identifies in the cyclization of both precursors to both products and also indicated that there was no appreciable exchange with exogenous inorganic pyrophosphate in the reaction. Subsequent incubations of each cyclase with [8,9-14C,1-18O]geranyl pyrophosphate and with (1E)-(+/-)-[1-3H,3-18O]linalyl pyrophosphate gave the appropriate (+)- or (-)-bornyl pyrophosphates, which were hydrolyzed in situ to the corresponding borneols. Analysis of the derived benzoates by mass spectrometry demonstrated each of the product borneols to possess an 18O enrichment essentially identical with that of the respective acyclic precursor. The absence of P alpha-P beta interchange and the complete lack of positional 18O isotope exchange of the pyrophosphate moiety are compatible with tight ion pairing of intermediates in the coupled isomerization-cyclization of geranyl pyrophosphate and establish a remarkably tight restriction on the motion of the transiently generated pyrophosphate anion with respect to its cationic terpenyl reaction partner.     

A biomimetic sensor for the determination of extracellular O(2)(-) using synthesized Mn-TPAA on TiO(2) nanoneedle film

By immobilizing synthesized Mn-TPAA (TPAA=tris[2-[N-(2-pyridylmethyl) amino] ethyl] amine) on TiO(2) nanoneedle surface, a biosensor for superoxide ion (O(2)(-)) has been developed and applied for determination of O(2)(-) released from living cells. Direct electron transfer of Mn-TPAA is realized with a formal redox potential (E°') falling in the range of the E°' values of the redox couples O(2)/O(2)(-) and O(2)(-)/H(2)O(2). This suggests that Mn-TPAA on TiO(2) films is electrochemically active and capable of thermodynamically mediating both the oxidation of O(2)(-) to O(2) and the reduction of O(2)(-) to H(2)O(2). Therefore, Mn-TPAA immobilized on the TiO(2) films can be used electrochemically for determination of O(2)(-) due to its electrochemical activities and biomimetic catalytic activities like superoxide dismutase (SOD) toward O(2)(-). The present biomimetic O(2)(-) sensor shows high selectivity at the low working potential of 0V vs. Ag|AgCl, a wide linear range from 10(-7)M to 10(-4)M and a quick response time within 6s. By taking advantage of the developed method and the properties of biomimetic SOD themselves, we have realized the real-time monitoring of O(2)(-) concentration released from living cells and investigated the relationship between the concentration changes of O(2)(-) and intracelluar Ca(2+), which may gain additional insights on the reactive oxygen species (ROS) signal transduction and other physiological and pathological events.     

Synthesis of (Rp,Rp)-P1,P4-Bis(5'-adenosyl)-1[17O,18O2],4[17O,18O2] tetraphosphate from (Sp,Sp)-P1,P4-Bis(5'-adenosyl)-1[thio-18O2], 4[thio-18O2]tetraphosphate with retention at phosphorus and the stereochemical course of hydrolysis by the unsymmetrical Ap4A phosphodiesterase from lupin seeds

The three stereoisomers of P1,P4-bis(5'-adenosyl)-1,4-dithiotetraphosphate have been synthesized and their 31P NMR spectra investigated. The effect of temperature on the circular dichroic spectrum of the (Sp,Sp)-stereoisomer shows that unstacking of the molecule occurs as the temperature is raised. Treatment of the (Sp,Sp)-stereoisomer with cyanogen bromide in [18O]water leads to substitution of sulfur by 18O with predominant retention of configuration at P1 and P4. (Sp,Sp)-P1,P4-Bis(5'-adenosyl)-1[thio-18O2],4[thio-18O2]tetraphosphate was synthesized and on treatment with cyanogen bromide in [17O]water gave (Rp,Rp)-P1,P4-bis(5'-adenosyl)-1[17O,18O2],4[17O,18O2]tetraphosphate. Hydrolysis by unsymmetrical Ap4A phosphodiesterase from lupin seeds gave (Rp)-5'-[16O,17O,18O]AMP. The reaction therefore proceeds with inversion of configuration at phosphorus, indicating that the enzyme-catalyzed displacement by water occurs by a direct "in-line" mechanism.     

Structure of the capsular polysaccharide of Escherichia coli O9:K32(A):H19

The capsular polysaccharide of the bacterium Escherichia coli O9:K32(A):H19 was analyzed using chemical methods (hydrolysis, sequential Smith degradation, methylation analysis) together with 1H- and 13C-n.m.r. spectroscopy. 13C-N.m.r. spectroscopy and chemical analyses indicated that the K32 polysaccharide is composed of equimolar proportions of glucose, galactose, rhamnose, and glucuronic acid, and carries O-acetyl groups. 1H-N.m.r. analysis of native K32 polysaccharide revealed five resonances in the anomeric region (delta 5.52, 5.16, 5.12, 5.02, and 4.73) and the presence of an acetyl group (delta 2.18). O-Deacetylation of the polysaccharide resulted in the loss of the resonance at delta 2.18 and one of the resonances (delta 5.52) in the anomeric region. The "extra" anomeric resonance in the 1H-n.m.r. spectrum of the native K32 polymer was assigned to H-2 of rhamnose, which experiences a large downfield shift when the 2-position is O-acetylated. This was confirmed by a 2D-COSY n.m.r. experiment and studies of model compounds. The K32 capsular polysaccharide is of the "2 + 2" type, comprised of the following repeating unit: (sequence; see text) This structure is identical to that of Klebsiella K55 capsular polysaccharide.     

Catalase enrichment using recombinant adenovirus protects alphaTN4-1 cells from H(2)O(2)

Since oxidative stress has been implicated in the development of numerous diseases including cataract, this laboratory has created and investigated the stress response of murine immortal lens epithelial cell lines (alphaTN4-1) conditioned to withstand lethal peroxide concentrations. Two of a group of antioxidative defense (AOD) enzymes found in such cells to have markedly enhanced activity are catalase (CAT) and GSH S-transferase alpha2 (GST). In order to determine if enrichment of one or both of these AODs is sufficient to protect alphaTN4-1 cells from lethal H(2)O(2) levels, these cells were infected with adenovirus vectors capable of expressing these AODs at a high level. With this system, gene enrichment and increased enzyme activity were observed with both CAT and GST vectors. The percentage of cells infected ranged from about 50 to 90% depending on the multiplicity of infection (MOI). CAT but not GST protected the cells from H(2)O(2) stress. The CAT activity was increased from 15- to 150-fold and even at the lower levels protected the cells from H(2)O(2) concentrations as high as 200 microM or more (H(2)O(2) levels which rapidly kill non-enriched cells). Even when only about 50% of the cell population is infected as judged by GFP infection, the entire population appeared to be protected based on cell viability. The CAT enrichment appears to protect other intracellular defense systems such as GSH from being depleted in contrast to non-enriched cell populations where GSH is rapidly exhausted. The overall results suggest that enriching the cellular CAT gene level with an appropriate recombinant viral vector may be sufficient to protect in vivo systems from peroxide stress.     

An N-[(R)-(-)-2-Hydroxypropionyl]-α-L-Perosamine Homopolymer Constitutes the O Polysaccharide Chain of the Lipopolysaccharide from Vibrio cholerae O144 Which Has Antigenic Factor(s) in Common with V. cholerae O76

Chemical and serological studies were performed with the lipopolysaccharide (LPS) from Vibrio cholerae O144 (O144). The LPS of O144 contained D -glucose, D -galactose, L -glycero-D -manno-heptose, D -fructose, D -quinovosamine (2-amino-2,6-dideoxy-D -gluco-pyranose) and L -perosamine (4-amino-4,6-dideoxy-L -manno-pyranose). The perosamine, a major component sugar of the LPS from O144, was in an L -configuration, as is also the case in the LPS from V. cholerae O76 (O76), in contrast to the D -configuration of the perosamine in the LPS of V. cholerae O1. A structural analysis revealed that the O polysaccharide chain of the LPS from O144 is an α(1 → 2)-linked homopolymer of (R)-(-)-2-hydroxypropionyl-L -perosamine. The serological cross-reactivity between O144 and O76 was clearly revealed by cross-agglutination and cross-agglutinin absorption tests with whole cells, as well as by passive hemolysis tests with sheep red-blood cells that had been sensitized with the LPS from O144 and O76. In contrast, in passive hemolysis tests, the LPS of O144 did not cross-react serologically with the LPSs from other strains such as V. cholerae O1 (Ogawa and Inaba), V. cholerae O140, Vibrio bio-serogroup 1875 (Original and Variant) and Yersinia enterocolitica O9. The LPSs from these strains consist of O polysaccharide chains composed of α(1 → 2)-linked homopolymers of D -perosamine with various N-acyl groups, and they share the Inaba antigen factor C of V. cholerae O1 in common. The results obtained in this study demonstrate that the absolute configuration of the perosamine residue in homopolymers plays a very important role in the expression of the serological specificity of the Inaba antigen factor C of V. cholerae O1.     

Cooperativity of thymopoietin 32-36 (the active site) and thymopoietin 38-45 in receptor binding

Thymopoietin is a 49 amino acid polypeptide hormone of the thymus whose biological activity is reproduced by the synthetic pentapeptide thymopentin, corresponding to amino acids 32-36. Thymopentin requires the addition of an octapeptide corresponding to thymopoietin 38-45 for full competition with native thymopoietin in a radioreceptor assay with receptor derived from the human T-cell line CEM. Thus thymopoietin appears to bind to its receptor on T-cells by two regions (32-36 and 38-45). Thymopentin alone is biologically active and induces elevations of intracellular cyclic GMP. Whilst occupancy of the adjacent site by thymopoietin 37-45 does not of itself cause an elevation of intracellular cyclic GMP this peptide is not biologically silent as it does enhance the potency of thymopentin.     

Embryotoxic effects of doxorubicin and N-trifluoroacetyladriamycin-14-valerate (AD-32)

Anthracyclines are mutagenic, carcinogenic, and also cardiotoxic. Concern has been shown over the use of anthracycline anticancer drugs during pregnancy as these may be teratogenic to the human fetus. We have performed a series of experiments using the chick embryo to investigate and compare the toxic and teratogenic effects of doxorubicin (DX) and its new analog N-trifluoroacetyladriamycin-14-valerate (AD-32). DX and AD-32, dissolved in 1:1 emulphor/ethanol and diluted to 1:4 with water, were injected into the air sac of white leghorn chick eggs at dose levels of 1-20 micrograms (DX) and 5-100 micrograms (AD-32) per egg. Eggs received a single injection of the drugs on days 1 and 2 of incubation. Control eggs were injected with an equivalent volume of the drug vehicle (0.05 ml per egg). Both of the drugs caused embryonic death, stunted growth, and various gross morphological malformations. Surviving embryos were sacrificed when they reached 13 days of incubation. The LD50 values for days 1 and 2 were as follows: (DX, 2.5 micrograms/egg on day 1 and 0.9 microgram/egg on day 2; AD-32, 10.6 micrograms/egg on day 1 and 11.8 micrograms/egg on day 2). Stunting of growth, a common anomaly with both drugs, decreased sharply from day 1 to day 2. The studies demonstrate that both DX and AD-32 are toxic and teratogenic during the period of early organogenesis in the chick embryos. However, the toxic and teratogenic potentials of DX and AD-32 differ quantitatively. AD-32 is a more potent teratogen than DX when injected on day 1.