Behçet's disease sera containing antiendothelial cell antibodies promote adhesion of T lymphocytes to cultured human dermal microvascular endothelial cells

Antiendothelial cell antibodies (AECA) have been detected in the sera of patients of autoimmune diseases showing vasculitis. Using IgM-ELISA, we found AECA in 42 (56%) of 75 sera samples from patients with Behçet's disease in a previous study. All of the 15 AECA-positive sera of Behçet's disease patients had an increased expression of the intercellular cell adhesion molecule-1 (ICAM-1), 93.3% of the sera induced the vascular cell adhesion molecule-1 (VCAM-1), and 100% of the serum induced the E-selectin molecule on human dermal microvascular endothelial cells (HDMEC). After stimulation of HDMEC with AECA-positive sera of Behçet's disease patients, the expression of ICAM-1 and VCAM-1 on HDMEC increased significantly at 4 hours, reaching a peak at 16 hours. Expression of E-selectin was induced at 1 hour after stimulation with a peak at 4 hours and it decreased thereafter. Adherence of T lymphocytes to HDMEC increased significantly after stimulation with AECA-positive sera from Behçet's disease patients. Also, the adherence of T lymphocytes to HDMEC increased at 4 hours and returned to its normal level at 48 hours. These results show that AECA-positive sera of Behçet's disease patients are capable of activating HDMEC to promote the adherence of T lymphocytes to increase the expression of ICAM-1, VCAM-1, and E-selectin on the cell surfaces. The whole process may play an important role in the pathogenesis of vasculitis in Behçet's disease.

Phenotyping of flavin-containing monooxygenase using caffeine metabolism and genotyping of FMO3 gene in a Korean population

Flavin-containing monooxygenase (FMO) activity was determined in 82 Korean volunteers by taking molar concentration ratio of theobromine and caffeine present in the 1 h urine (between 4 and 5 h) samples collected after administration of a cup of coffee containing 110 mg of caffeine. Among 82 volunteers, there were 19 women and 63 men (30 smokers and 52 non-smokers). Volunteers were divided into two groups comprising low (0.53-2.99) and high (3.18-11.95) FMO activities separated by an antimode of 3.18. Peripheral bloods were sampled from these volunteers and their genomic DNAs were amplified by polymerase chain reaction with oligonucleotides designed from intronic sequences of human FMO3 gene. Comparing nucleotide sequences of the amplified FMO3 gene originating from randomly selected individuals with low and high FMO activities, nine point mutations were identified in the open reading frame sequences. Among these nine mutations, three FMO3 mutant types (FMO3/Stop148, Lys158 and Gly308) were selected and correlated with FMO activities observed in our Korean population. A rare FMO3/Stop148 mutant allele originating from FMO3/Gly148 occurred by substitution of G442T in exon 4 and yielded a premature TGA stop codon. The stop codon was detected in one individual having the second lowest FMO activity and he had the mutation in heterozygous state. In a pedigree study, he was found to have inherited the mutation from his mother who also had a heterozygous stop codon and equally low FMO activity. In our volunteers, two other common mutations were detected in exons 4 and 7. The one in exon 4 resulted from a G472A change eliminating a HinfI restriction site and produced an amino acid substitution from Glu158 to Lys. The other mutation in exon 7 resulted from an A923G change generating a DraII restriction site and produced a non-conservative replacement of Glu308 to Gly. Based on the secondary structure maps of FMO3 enzyme proteins for these two mutant types, FMO3/Gly308 mutation transformed the helix structure into a sheet shape and indicated that dysfunctional FMO3 may be produced. FMO3/Lys158 mutation did not alter the secondary structure. Approximately 80% of volunteers with homozygous and/or heterozygous mutations on either one or two of these mutations had low FMO activities. Thus, individuals with these FMO3 gene mutations may have defective metabolic activity for many clinically used drugs and dietary plant alkaloids which are oxidized primarily by hepatic FMO3.

Generation of HLA-DP transgenic pigs for the study of xenotransplantation

The shortage of human organs has prompted scientists to seek xenogeneic sources of donors. To date, DAF, MCP, and CD59 transgenic pigs have been generated to inhibit hyperacute rejection. However, besides hyperacute rejection, acute and chronic rejection must also be considered in the use of porcine organs for xenotransplantation. The role of HLA-II in transgenic xeno-organ transplantation remains to be elucidated. By microinjecting 1655 embryos, we have generated one stillborn HLA-DR and two live HLA-DP transgenic pigs: P113-7 (male, carrying one copy of exogene) and P113-8 (female, carrying 2-3 copies of exogenes). The gene status of the live transgenic pigs was confirmed by PCR, Southern blot, and PCR product sequencing analysis. The expression of transgenes in these transgenic pigs were confirmed by RT-PCR analysis and immunohistochemical staining of frozen sections of ear tissue.

Proteome analysis of factor for inversion stimulation (Fis) overproduction in Escherichia coli

The factor-for-inversion stimulation protein (Fis) is a global regulatory protein in Escherichia coli that activates ribosomal RNA (rRNA) transcription by binding to three upstream activation sites of the rRNA promoter and enhances transcription 5- to 10-fold in vivo. Fis overexpression results in different effects on cell growth depending on nutrient conditions. Differential proteome analysis of Fis-expressing cells shows ten protein spots corresponding to Fis overexpression in both rich (YT) and minimal (M9+glucose) media. Three of these spots have been identified as elongation factor TS, histidine-binding periplasmic protein precursor, and ketol-acid reductoisomerase.

Prognostic value of DNA flow cytometry in stomach cancer: a 5-year prospective study

The role of DNA flow cytometry in the prediction of prognosis for patients with stomach cancer remains to be defined. Thus we studied prospectively the role of DNA flow cytometry as a prognosis indicator in stomach cancer patients in a high-incidence area. Between November 1990 and December 1992, primary stomach cancer tissues were obtained from the surgical specimens from 217 patients (148 male, 69 female). DNA flow cytometric analyses of DNA ploidy and S-phase fraction were performed and the results were correlated with patient survival. The median age of the patients was 55 years (range 24-78). Aneuploid cell population was found in 114 of 217 samples (53%). Tumour S-phase fraction was obtained in 96 of 103 diploid tumours (93%) and 61 of 114 aneuploid tumours (54%). After median follow-up of 66.1 months, the patients with tumours with an S-phase fraction over 17% had significantly worse survival rates than patients with tumours with S-phase fractions of lower than 8% or 8-17% (45% vs 59% and 63% of patients surviving, P = 0.007). Tumour ploidy status did not correlate with patient survival. Multivariate analyses showed that the TNM stage remained the most important prognostic indicator. The tumour S-phase fraction was also an independent prognostic indicator (relative risk 2.300, 95% CI, 1.252-4.223). Tumour S-phase fraction obtained by DNA flow cytometry is an independent prognostic indicator for the survival of the patients with stomach cancer.

Rapid and sensitive determination of paclitaxel in mouse plasma by high-performance liquid chromatography

This report describes a rapid, simple and sensitive isocratic high-performance liquid chromatography with diode array UV detection for micro-sample analysis of paclitaxel in mouse plasma. The analysis utilized a Capcell-pak octadecyl analytical column and a mobile phase consisting of acetonitrile--0.1% phosphoric acid in deionized water (55:45, v/v). Paclitaxel and n-hexyl p-hydroxybenzoic acid (internal standard) were extracted from plasma by one-step extraction with tert.-butyl methyl ether. Peak purity was determined over a UV wavelength range of 200 to 400 nm. Paclitaxel and the internal standard were eluted at 3.4 min and 5.4 min, respectively, at a mobile phase flow-rate of 1.3 ml/min. No interfering peaks were observed and the total run time was 10 min. The standard curve was linear (r = 0.9999) over the concentration range of 0.010-500 micrograms/ml. The extraction recovery was > 90% for both paclitaxel and n-hexyl p-hydroxybenzoic acid. The intra- and inter-day assay variabilities of paclitaxel ranged from 0.4 to 2.2% and 0.6 to 7.8%, respectively. The LOD and LOQ were 5 and 10 ng/ml, respectively, for paclitaxel using a plasma sample volume of 100 microliters. This highly sensitive and simple assay method was successfully applied to a pharmacokinetic study after i.v. administration of paclitaxel 20 mg/kg to mice.

Antitumor agents 187: synthesis and cytotoxicity of substituted 8,8-dimethyl-2H,8H-pyrano[6,5-h]quinoline-2-one and related compounds

Several substituted 8,8-dimethyl-2H,8H-pyrano[6,5-h]quinoline-2-ones and related compounds were synthesized and evaluated for their in vitro cytotoxicity against a panel of human tumor cell lines. The most active compound (3) showed significant cytotoxic activity with GI50 values in the micromolar range.

Recent advances in the discovery and development of quinolones and analogs as antitumor agents

Compounds that interact with DNA or microtubules by multiple mechanisms and cause diverse cytotoxic lesions are potential targets for anticancer drug development. Accordingly, a relatively new approach to the rational design of antitumor agents is based on the quinolone class of antibacterials. Their mechanism of antibacterial action involves inhibition of DNA gyrase, and numerous new quinolones do exhibit antitumor activity. Thus, these new quinolone structures display a novel mode of action for the quinolone class as antitumor agents. The potential for quinolones to be used as topoisomerase II inhibitors, as well as antimitotic agents, is reviewed with a focus on recent discoveries and development of antitumor quinolones, especially related work in the author's laboratory.

Rabbits treated with chronic isepamicin are resistant to mivacurium and rocuronium

We compared the dose-response relationships and the neuromuscular blocking effects of mivacurium and rocuronium after chronic isepamicin therapy for 7 days in 56 anesthetized rabbits. Train-of-four stimuli were applied every 10 s to the common peroneal nerve, and the force of contraction of the tibialis anterior muscle was measured. Chronic isepamicin therapy is associated with a rightward shift of the mivacurium and rocuronium dose-response curves. The effective dose for 50% twitch depression of mivacurium and rocuronium increased significantly, from 16.9 +/- 4.8 and 56.5 +/- 5.3 microg/kg, respectively, with placebo to 30.6 +/- 5.3 and 75.6 +/- 4.7 microg/kg, respectively, during isepamicin therapy. The isepamicin rabbits receiving mivacurium 0.18 mg/kg or rocuronium 0.6 mg/kg had an accelerated recovery from neuromuscular blockade compared with those receiving placebo. The results of this study show that mivacurium and rocuronium have both a decreased effect and a shorter duration of action in rabbits when used during concurrent isepamicin therapy.

IMPLICATIONS

We studied the dose-response relationships and the neuromuscular blocking effects of mivacurium and rocuronium during chronic isepamicin therapy in rabbits. Mivacurium and rocuronium have both a decreased effect and a shorter duration of action during chronic aminoglycoside antibiotic therapy in rabbits.

Frequency of spinocerebellar ataxia types 1,2,3,6,7 and dentatorubral pallidoluysian atrophy mutations in Korean patients with spinocerebellar ataxia

Autosomal dominant cerebellar ataxias (ADCAs) are a heterogeneous group of disorders characterized by degenerative symptoms in the cerebellum, spinal cord, and brain stem. Six different genes have been reported to be associated with ADCA, and the length of trinucleotide repeats of these genes is correlated with the age at onset and severity of symptoms. Although there are strong hereditary effects in these disorders, most of the studies carried out in heterogeneous populations and in small groups obscure the true incidence of these diseases. We examined the frequency of six types of ADCAs in 87 unrelated Korean patients with progressive ataxia and compared the results to the frequencies in other ethnic groups. Spinocerebellar ataxia (SCA) type 2 was the most frequent hereditary ataxia (12.6%) and types 3 and 6 accounted for 4.6% and 6.9% of ataxia patients, respectively. Dentatorubral pallidoluysian atrophy was also found in three patients (3.4%). No instances of SCA types 1 or 7 were detected. These findings show the striking contrast to the white population and a difference from Japanese findings. Our results demonstrate that dentatorubral pallidoluysian atrophy should be included in the differential diagnosis of Korean patients with spinocerebellar ataxia, and that there are strong hereditary effects in patients with ADCAs.

Insulin-like growth factor-I (IGF-I) ameliorates and IGF binding protein-1 (IGFBP-1) exacerbates the effects of undernutrition on brain growth during early postnatal life: studies in IGF-I and IGFBP-1 transgenic mice

Insulin-like growth factor-I (IGF-I) plays an important role in the stimulation of postnatal brain growth. In transgenic (Tg) mice, IGF-I overexpression stimulates postnatal brain growth, whereas decreased IGF-I availability caused by ectopic brain expression of IGF binding protein-1 [(IGFBP-1), an inhibitor of IGF-I action] retards postnatal brain growth. Because undernutrition during early postnatal development profoundly retards growth and maturation of the brain in rodents, we sought to determine the influence of IGF-I on undernutrition-induced brain growth retardation. Caloric restriction was imposed on IGF-I Tg mice, IGFBP-1 Tg mice, and their non-Tg littermates by separating half of each litter from their dams during the suckling period, postnatal d 1 to 21. Undernutrition reduced the brain growth of each group of mice, but the growth of undernourished IGF-I Tg mice was comparable to that of well-fed control mice (increased 4.13- and 4.22-fold, respectively) and greater than that of undernourished control mice (increased 3.45-fold), whereas undernourished IGFBP-1 Tg mice exhibited less growth (increased 3.15-fold) than undernourished control mice. When the effects of undernutrition were examined in specific brain regions of each group, the same pattern was observed, and IGF-I was found to be more effective in preserving the growth of the regions with the highest transgene expression (cerebral cortex, hippocampus, and diencephalon). Despite undernutrition, IGF-I transgene expression stimulated overgrowth of these regions as well as that of the posterior medial barrel subfield, a somatosensory area of the cerebral cortex in which IGF-I may be especially important in development. These data indicate that IGF-I can ameliorate the brain growth retardation caused by undernutrition imposed during development, although it is unclear whether IGF-I directly opposes the impact of undernutrition or acts independently of nutritional status. Nonetheless, these findings raise the possibility that the relatively high IGF-I expression during early postnatal life may be responsible for sparing the brain from the full impact of undernutrition during this time in development.

Are substance P neurons of the paraventricular nucleus related to the osmotic regulation in the Mongolian gerbil?

In recent years, the gerbil has been used as an experimental animal for study osmotic regulation, because of its inherent high degree of water re-uptake in kidney. Many evidences to explain this characteristic accumulated on the kidney level, it do not, however, manifest what concerns on hypothalmo-hypophyseal level. In this study, we have focused on the difference between the colchicine treated gerbil and rat in distributions of substance P (SP), which is known to have antidiuretic property. Unlike rat, in which a few SP+ neuron is present, SP+ neurons were abundantly observed in the paraventricular nucleus (PVN) of the gerbil. Furthermore SP+ cells in PVN were manifested in dehydrated gerbils, in spite of non-colchicine treatment. Therefore, we suggest that the abundant SP+ neurons in PVN may be a clue to address the neuroendocrinal mechanism concerning the high degree of osmotic regulation in this animal.

Conjugation of drug to poly(D,L-lactic-co-glycolic acid) for controlled release from biodegradable microspheres

Poly(d,l-lactic-co-glycolic acid) (PLGA) was chemically conjugated to a model drug, N-(9-fluorenylmethoxycarbonyl-N-tert-butoxycarbonyl-l-tryptophan (Fmoc-Trp(Boc)) via an ester linkage. Various coupling reaction conditions were tested to optimize the conjugation process between a hydroxyl terminal group of PLGA and a carboxylic acid group of Fmoc-Trp(Boc). Two different lactic/glycolic acid compositions of PLGA (50/50 and 75/25) were used for the conjugation. The Fmoc-Trp(Boc)-PLGA conjugates were formulated into microspheres by a solvent evaporation technique for controlled release of Fmoc-Trp(Boc) over an one month period. A linear constant release of Fmoc-Trp(Boc) and its water-soluble PLGA oligomer conjugates was observed over an extended period without any initial burst effect, while unconjugated Fmoc-Trp(Boc) encapsulated within microspheres exhibited a rapid release profile. In addition, Fmoc-Trp(Boc) release rate solely depended on the PLGA composition that affected polymer degradation rate. The release rate of Fmoc-Trp(Boc) conjugated with fast degrading 50/50 PLGA was more rapid than that conjugated with relatively slow degrading 75/25 PLGA. This study demonstrates that PLGA-drug conjugation approach is a new and novel strategy to control the drug release rate from PLGA microspheres by utilizing the chemical degradation rate of PLGA backbone.

Rat osteopontin antibody is cross-reactive to a novel myelin-associated protein in chick

Osteopontin (OPN) was initially identified as glycosylated phosphoprotein in bones of vertebrates. Recently, OPN is reported to express in the primitive neuroepithelia of early chick embryonic hindbrain. We have demonstrated that rat OPN is immunohistochemically localized in the white matter of chick CNS. We have further confirmed the specificity of OPN cross-immunoreaction in myelin using demyelinated optic nerve induced by lysophosphatidylcholine (LPC), where the intensity of immunoreaction was closely related to the degree of demyelination. Immunoblot analyses showed that rat OPN antibody recognized a protein with molecular weights of approximately 47 kDa from chick CNS. Our data suggest that the antigen recognized by rat OPN is a previously undescribed myelin-associated protein in the chick CNS.

Lectins isolated from Korean mistletoe (Viscum album coloratum) induce apoptosis in tumor cells

Cytotoxic lectins (KML-C) were isolated from an extract of Korean mistletoe [Viscum album C. (coloratum)] by affinity chromatography on a hydrolysed Sepharose 4B column, and the chemical and biological properties of KML-C were examined, partly by comparing them with a lectin (EML-1) from European mistletoe[Viscum album L. (loranthaceae)]. The hemagglutinating activity of KML-C was inhibited by N-acetyl-D-galactosamine and D-galactose at the minimum concentrations of 6.3 and 12.5 microM/ml, respectively. Further biochemical analyses indicated that KML-C consists of four chains (Mr = 27.5, 30, 31 and 32.5 kDa) which, in some of the molecules, are disulfide-linked, and that the chains of KML-C are distributed over a broad range of isoelectric points (pI), 8.0 to 9.0, whereas the range for EML-1 is 6.6-7.0. A difference was also observed between the N-terminal sequences of KML-C and EML-1. The isolated lectins showed strong cytotoxicity against various human and murine tumor cells, and the cytotoxic activity of KML-C was higher than that of EML-1. Tumor cells treated with KML-C exhibited typical patterns of apoptotic cell death, such as apparent morphological changes and DNA fragmentation, and its apoptosis-inducing activity was blocked by addition of Zn2+, an inhibitor of Ca2+/Mg2+ -dependent endonucleases, in a dose-dependent manner. These results suggest that KML-C is a novel lectin related to the cytotoxicity of Korean mistletoe, and that its cytotoxic activity against tumor cells is due to apoptosis mediated by Ca2+/Mg2+ -dependent endonucleases.

Tumor necrosis factor alpha decreases the viability of mouse blastocysts in vitro and in vivo

Mouse blastocysts were exposed for 24 h to various concentrations of recombinant mouse tumor necrosis factor alpha (TNFalpha) and observed for their capacity to implant in vitro on a fibronectin-coated substrate or to develop in vivo after their transfer into surrogate females. Compared with findings in control blastocysts, exposure to TNFalpha resulted in a significant reduction in the average number of cells in the inner cell mass (ICM) lineage. This effect was associated with a significant increase in the frequency of cells identified as engaged in apoptosis by means of the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling technique. No difference was found in the incidence of nuclear fragmentation between control and TNFalpha-exposed blastocysts. When TNFalpha-pretreated blastocysts were allowed to implant in vitro, significantly fewer embryos were able to maintain a structured ICM cluster at the center of the trophectoderm outgrowth. Although no difference was found in the average surface area of the outgrowths, implants derived from TNFalpha-treated blastocysts contained significantly fewer nuclei than implants from control embryos. After transfer into recipient mice, TNFalpha-pretreated blastocysts implanted at about the same rate as control embryos, but a significantly higher rate of resorption was found among fetuses after exposure to the cytokine. In addition, the weight of the surviving fetuses was significantly lower than for control fetuses. These data indicate that the impact of TNFalpha on blastocysts is specifically aimed at the ICM lineage and that TNFalpha decreases the ability of embryos to differentiate into fetuses after implantation.

Microbiota of successful osseointegrated dental implants

BACKGROUND

The long-term survival of dental implants depends, in part, on control of bacterial infection in the peri-implant region. Periodontal pathogens colonized implants symptomatic through infection, whereas the microbiota of successful implants was similar to that of periodontal health. This study examined the impact on the peri-implant microbiota of crown restorations; implant type; length of time of loading; history of implant or periodontal infections; and whether implants replaced single or multiple teeth. It was of particular interest to evaluate implant colonization by species in a newly described red complex of periodontal pathogens, Porphyromonas gingivalis and Bacteroides forsythus.

METHODS

This study sampled 43 partially edentulous subjects with successfully osseointegrated titanium root-form dental implants. Eighty-one (81) non-submerged and 20 submerged asymptomatic implants, 83 crowned, and 36 uncrowned teeth were sampled from peri-implant or subgingival sites. The microbiota of samples was evaluated using whole genomic DNA probes in a checkerboard assay to 23 subgingival species.

RESULTS

Implants were colonized principally by oral streptococci, capnocytophagae, Veillonella parvula, Peptostreptococcus micros, and Fusobacterium nucleatum. The periodontal species, P. gingivalis, B. forsythus, Prevotella intermedia, Prevotella nigrescens, and Campylobacter rectus were detected in a few subjects. The microbiota around crowned implants and crowned teeth was similar. Streptococcus oralis, P. intermedia, and Selenomonas noxia were elevated in samples from uncrowned teeth compared to crowned teeth and implants. Microbial complexity increased as loading time increased, but colonization by periodontal pathogens, including red complex species, was higher in subjects with previous periodontal disease. No differences were observed in the microbiota of 1- and 2-stage implants, or between implants supporting single or multiple restorations.

CONCLUSIONS

While presence of crowns had only a minor impact on the peri-implant microbiota, microbial changes were observed the longer the implants had been in function and in those patients with a history of periodontal or peri-implant infections. A history of periodontitis had a greater impact on the peri-implant microbiota than implant loading time. The major influence on the peri-implant microbiota was, however, the microbiota on remaining teeth. P. gingivalis and B. forsythus, red complex periodontal pathogens, colonized several implants, although all implants were successfully osseointegrated.

Antitumor agents. 190. Absolute stereochemistry of the cytotoxic germacranolides, tomenphantins A and B, from Elephantopus tomentosus

The structures and absolute stereochemistries of tomenphantins A (1) and B (2), cytotoxic germacranolides isolated from Elephantopus tomentosus, are reported herein. 1H and 13C NMR spectroscopic data, chemical transformation, and single-crystal X-ray analysis were used in these determinations.

Interaction of novel thiocolchicine analogs with the tubulin isoforms from bovine brain

The antimitotic alkaloid colchicine binds to tubulin and inhibits microtubule assembly. Recently a new series of colchicine derivatives has been synthesized in which the seven-membered B-ring was shortened to a six-membered ring. In an effort to study the role of the B-ring substituents in this new series, we have studied the interaction of two compounds of this series, THC 5 and THC 18, with tubulin isoforms from bovine brain. We find that THC 18, which has a side chain with a pi-bonded SP2 conformation, binds differently to the tubulin isoforms, while THC 5 with a slightly different side chain does not. The results indicate that the conformation of the B-ring domain plays a major role in the differential interaction of a colchicine derivative with different tubulin isoforms. The results will be very important in designing potent antitumor derivatives of colchicine.

Synthesis and anticancer evaluation of certain alpha-methylene-gamma-(4-substituted phenyl)-gamma-butyrolactone bearing thymine, uracil, and 5-bromouracil

Certain alpha-methylene-gamma-(4-substituted phenyl)-gamma-butyrolactone bearing thymine, uracil, and 5-bromouracil were synthesized and evaluated for their anticancer activity. These compounds demonstrated a strong growth inhibitory activity against leukemia cell lines. The anticancer potency for the substituents of the lactone C(gamma)-phenyl is in an order of 4-Ph > 4-Cl, 4-Br > 4-Me, 4-NO2 > 4-F. For the pyrimidine portion, 5-bromouracil is more potent than uracil and thymine.

Substituted 7H-pyrido[4,3-c]carbazoles with potent anti-HIV activity

Several substituted 7H-pyrido[4,3-c]carbazoles were synthesized from the natural product mukonal and tested for inhibition of HIV replication in H9 lymphocytes. 5-Methoxy-7-methyl-7H-pyrido[4,3-c]carbazole (7) had an EC50 value of 0.0054 microgram/mL and the highest therapeutic index (TI = 503) in the series.

Calcium-dependent interaction of annexin I with annexin II and mapping of the interaction sites

Annexins are multifunctional intracellular proteins with Ca2+- and phospholipid-binding properties. Their structures consist of four conserved repeat domains that form the core and a diverse N-terminal tail, from which their functional differences may arise. We searched for cellular proteins that interact with the N-terminal tail plus domain I of annexin I (ANX1) by using the yeast two-hybrid method. Screening of a HeLa cell cDNA library yielded annexin II (ANX2) cDNA. The interaction between ANX1 and ANX2 also occurred in vitro in a Ca2+-dependent manner. Mapping of the interaction sites revealed that interaction between domain I of ANX1 and domain IV of ANX2 was stronger than the other combinations.