Centrality dependence of charged particle multiplicity in Au-Au collisions at square root of (s)NN = 130 GeV

We present results for the charged-particle multiplicity distribution at midrapidity in Au-Au collisions at square root of [s(NN)] = 130 GeV measured with the PHENIX detector at RHIC. For the 5% most central collisions we find dN(ch)/d eta(vertical line eta = 0) = 622+/-1(stat)+/-41(syst). The results, analyzed as a function of centrality, show a steady rise of the particle density per participating nucleon with centrality.

Serum 8-hydroxy-guanine levels are increased in diabetic patients

OBJECTIVE

The production of reactive oxygen species is increased in diabetic patients, especially in those will poor glycemic control. We have investigated oxidative damage in type 2 diabetic patients using serum 8-hydroxyguanine (8-OHG) as a biomarker.

RESEARCH DESIGN AND METHODS

We studied 41 type 2 diabetic patients and compared them with 3 nondiabetic control subjects. Serum 8-OHG concentration was assayed using high-pressure liquid chromatography.

RESULTS

The type 2 diabetic patients had significantly higher concentrations of 8-OHG in their serum than the control subjects (5.03 +/- 0.69 vs. 0.96 +/- 0.15 pmol/ml P < 0.01). There was no association between the levels of 8-OHG and HbA1c. We also could not and any correlation between serum 8-OHG levels and age, duration of diabetes, serum lipids, or creatinine or albumin exeretion rate. Creatinine clearance showed marginal correlation with serum 8-OHG levels (P = 0.06). Among the diabetic patients, those with proliferative retinopathy had significantly higher 8-OHG levels than those with nonproliferative retinopathy or without retinopathy. Likewise, the serum 8-OHG levels in patients who had advanced nephropathy (azotemia) were higher than in patients with normoalbuminuria, microalbuminuria, or overt proteinuria.

CONCLUSIONS

Our findings show that measuring serum 8-OHG is a novel convenient method for evaluating oxidative DNA damage. Diabetic patients, especially those with advanced microvascular complications, had significantly higher serum 8-OHG levels; this suggests that such changes may contribute to the development of microvascular complications of diabetes.

Ceramide inhibits cell proliferation through Akt/PKB inactivation and decreases melanin synthesis in Mel-Ab cells

Ceramide is a bioactive sphingolipid that mediates a variety of cell functions. However, the effects of ceramide on cell growth and the melanogenesis of melanocytes are not known. In the present study, we investigated the actions of cell-permeable ceramide and its possible role in the signaling pathway of a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Our results show that C2-ceramide inhibits DNA synthesis in Mel-Ab cells and G361 human melanoma cells in a dose-dependent manner. Cell cycle analysis confirmed the inhibition of DNA synthesis by a reduction in the S phase. To investigate the ceramide signaling pathway, we studied whether C2-ceramide is able to influence extracellular signal-regulated kinase (ERK) and/or Akt/protein kinase B (PKB) activation. We demonstrated that phosphorylated Akt/PKB is decreased by C2-ceramide, whereas phosphorylated ERK was only slightly affected. Therefore, the C2-ceramide-induced inactivation of Akt/PKB may be closely related to the reduced cell proliferation of Mel-Ab cells. Furthermore, we assessed the effects of C2-ceramide on the pigmentation of Mel-Ab cells. The results obtained showed that the melanin content of cells was significantly reduced by C2-ceramide at concentrations in the range of 1-10 microM, and that the pigmentation-inhibiting effect of C2-ceramide is much greater than that of kojic acid at 1-100 microM. In addition, we found that the activity of tyrosinase is reduced by C2-ceramide treatment. Our results demonstrate that C2-ceramide reduces the pigmentation of Mel-Ab cells by inhibiting tyrosinase activity.

Clinical impacts of tumor cell contamination of hematopoietic stem cell products in metastatic breast cancer patients undergoing autologous peripheral blood stem cell transplantation: multicenter trial

To determine whether the tumor cell contamination of peripheral blood stem cells influences clinical impacts on high-dose chemotherapy in patients with metastatic breast cancer, we analyzed carcinoembryonic antigen (CEA) mRNA in the apheresis products by nested RT-PCR (reverse transcriptase-polymerase chain reaction). A total of 38 metastatic breast cancer patients and ten normal healthy subjects as a negative control were included. Twenty out of 38 (51.3%) apheresis products from patients with metastatic breast cancer were positive for CEA mRNA. CEA mRNA was noted in 54.8% (17/31) of patients mobilized with chemotherapy plus G-CSF and 42.8% (3/7) of patients with G-CSF alone. There was no significant difference in age, estrogen receptor, menopausal status, mobilization method, disease free interval, or number of metastasis sites (1 vs > or = 2) between positive and negative groups. The presence of CEA mRNA in apheresis products did not influence the time to progression and overall survival in both groups. However, both the univariate and the multivariate analysis disclosed that the number of metastasis was associated with survival significantly. We suggest that the tumor cell contamination does not predict poor treatment outcome in patients with metastatic breast cancer.

Nuclear localization of beta-catenin is an important prognostic factor in hepatoblastoma

In this study, mutational and immunohistochemical analyses of beta-catenin were performed in 30 hepatoblastomas, to assess the prevalence of alterations of the Wnt pathway with respect to clinicopathological parameters and survival. Four missense mutations of beta-catenin (13.3%) were detected and there was strong immunoreactivity for beta-catenin in the cytoplasm and/or the nucleus in 97% of hepatoblastomas. Nuclear and cytoplasmic staining was demonstrated in 19 of 30 tumours (63%), while ten revealed only cytoplasmic staining. Statistically, this nuclear beta-catenin staining was significantly higher in the embryonal (Fisher exact test; p=0.00393) or undifferentiated type (p=0.00156) of hepatoblastoma than in the fetal type, but there was no difference between clinical stages I and II and clinical stages III and IV (p=0.175). Cumulative survival curves showed that nuclear beta-catenin staining (generalized Wilcoxon test; p=0.0088), undifferentiated histological type (p=0.0305), and clinical stages III and IV (p=0.0107) were significantly correlated with shorter survival time in these patients. Moreover, Cox multivariate analysis provides evidence that nuclear beta-catenin staining is the most important prognostic factor for survival (p=0.0090). It is therefore concluded that immunohistochemical analysis of beta-catenin might be a useful clinical tool for estimating the prognosis for patients with hepatoblastoma.

Increased erythritol production in fed-batch cultures of Torula sp. by controlling glucose concentration

The effect of glucose concentration on erythritol production by Torula sp. was investigated. The maximum volumetric productivity of erythritol was obtained at an initial glucose concentration of 300 g l(-1) in batch culture. The volumetric productivity was maximal at a controlled glucose concentration of 225 g l(-1), reducing the lag time of the erythritol production. A fed-batch culture was established with an initial glucose concentration of 300 g l(-1) and with a controlled glucose concentration of 225 g l(-1) in medium containing phytic acid as a phosphate source. In this fed-batch culture, a final erythritol production of 192 g l(-1) was obtained from 400 g l(-1) glucose in 88 h. This corresponded to a volumetric productivity of 2.26 g l(-1) h(-1) and a 48% yield.

Fatty acid patterns in gastric mucosa of stomach cancer patients

omega6 and omega3 fatty acids are important cellular components and known to be involved in disease processes. However, few studies have focused on mucosa fatty acid in human gastric cancer. The purpose of this study was to investigate how fatty acid patterns of mucosa are altered in gastric cancer. Fatty acids were analyzed by gas chromatography and their relative compositions (%) were determined and evaluated both in mucosa total-fatty acids and in phospholipid-fatty acids in paired cancerous and non-cancerous gastric cancer tissues (n = 18). The level of arachidonic acid (20:4omega6, AA) appeared significantly higher both in phospholipid-fatty acids (p < 0.05) and in total-fatty acids (p < 0.001) in cancerous mucosa compared to non-cancerous mucosa. The omega6/omega3 fatty acid ratio of phospholipid-fatty acids was also significantly higher in cancerous mucosa. The higher level of AA in cancerous tissue can be partially explained by the higher ratio of 20:4omega 6/20:3omega6 (desaturation index) and the lower ratio of 22:4omega6/20:4 omega6 (elongation index). The change in the relative composition of arachidonic acid may influence the production of prostaglandins and related metabolites, which regulate cell differentiation and proliferation. The findings of this study with respect to fatty acid changes, especially in terms of arachidonic acid metabolism, may be of relevance in the understanding of the roles of specific fatty acids and possibly of eicosanoids in gastric cancer.

Cloning and characterization of the Hansenula polymorpha homologue of the Saccharomyces cerevisiae MNN9 gene

A gene homologous to Saccharomyces cerevisiae MNN9 has been cloned and characterized in the methylotrophic yeast Hansenula polymorpha. This gene was cloned from a H. polymorpha genomic DNA library using the S. cerevisiae MNN9 gene as a probe. The H. polymorpha MNN9 homologue (HpMNN9) contained a 1062 bp open reading frame encoding a predicted protein of 354 amino acids. The deduced amino acid sequence showed 58% and 51% identity, respectively, with the S. cerevisiae and Candida albicans Mnn9 proteins. Disruption of HpMNN9 leads to phenotypic effects suggestive of cell wall defects, including detergent sensitivity and hygromycin B sensitivity. The hygromycin B sensitivity of S. cerevisiae mnn9 null mutant was complemented in the presence of the HpMNN9 gene. The DNA sequence of the H. polymorpha homologue has been submitted to GenBank with the Accession No. AF264786.

Wegener's granulomatosis presenting as mediastinal soft tissue mass invading the tracheal wall

Wegener's granulomatosis (WG) is a clinicopathologic entity of unknown cause characterised by a necrotising granulomatous vasculitis affecting multiple organs, especially the upper and lower respiratory tracts, lung and kidney. The lung is the most frequently, and sometimes the only involved organ. Single or multiple nodules, with or without cavitation, are the most common pulmonary manifestations in WG, but mediastinal involvement is atypical. The sole tracheal involvement is rare and hilar and mediastinal involvement has been thought not to be part of the clinical feature. We experienced a rare case of WG presenting as paratracheal mediastinal lesions with tracheal wall invasion, which responded dramatically to corticosteroid treatment. We present this case with a review of the literature.

Burkitt's lymphoma presenting as ileocaecal intussusception in systemic lupus erythematosus

Patients with systemic lupus erythematosus (SLE) are reported to have an increased risk of malignancy, especially lymphoproliferative disorders. We decribe the occurrence of ileocaecal intussusception secondary to Burkitt's lymphoma in a patient with SLE. A 23-year-old woman, who had been diagnosed with SLE 2 years ago, developed intermittent abdominal pain with a palpable mass. Computed tomography and a double-contrast barium enema showed a lobulated mass with intussusception at the ileocaecal junction. Right hemicolectomy and splenectomy was performed after histopathological examinations on colonoscopic biopsy revealed Burkitt's lymphoma. Fourteen months after chemotherapy, there is no evidence of recurrence of the Burkitt's lymphoma. When a patient with SLE has abdominal complaints, besides serositis, lupus enteritis such as peptic ulcer disease, mesenteric vasculitis with or without complications and pancreatitis, we have to consider intussusception secondary to gastrointestinal lymphoma as one of the differential diagnoses. Therefore, we should thoroughly investigate patients with SLE presenting with abdominal pain and not simply consider it afeature of lupus enteritis until other causes have been ruled out.

Induction of early growth response-1 gene expression by calmodulin antagonist trifluoperazine through the activation of Elk-1 in human fibrosarcoma HT1080 cells

The early growth response gene-1 (Egr-1) is a transcription factor that plays an important role in cell growth and differentiation. It has been known that Egr-1 expression is down-regulated in many types of tumor tissues, including human fibrosarcoma HT1080 cells, and introduction of the Egr-1 gene into HT1080 cells inhibits cell growth and tumorigenic potential. Trifluoperazine (TFP), a phenothiazine class calmodulin antagonist, is known to inhibit DNA synthesis and cell proliferation and potentially important in antitumor activities. To understand the regulatory mechanism of Egr-1, we investigated the effect of TFP on expression of Egr-1 in HT1080 cells. Herein, we report that Egr-1 expression was increased by TFP in synergy with serum at the transcriptional level. Both the Ca(2+)/calmodulin-dependent protein kinase II inhibitor KN62 and the calcineurin inhibitor cyclosporin A enhanced TFP-dependent increase of Egr-1, suggesting that the Ca(2+)/calmodulindependent pathway plays a role in regulation of Egr-1 expression in HT1080 cells. The TFP-stimulated increase of the Egr-1 protein was preferentially inhibited by the MEK-specific inhibitor PD98059. In addition, activation of human Egr-1 promoter and the transcriptional activation of the ternary complex factor Elk-1 induced by TFP were inhibited both by pretreatment of PD98059 and by expression of the dominant-negative RasN17. These results indicate that the Ras/MEK/Erk/Elk-1 pathway is necessary for TFP-induced Egr-1 expression. We propose that the calmodulin antagonist TFP stimulates Egr-1 gene expression by modulating Ras/MEK/Erk and activation of the Elk-1 pathway in human fibrosarcoma HT1080 cells.

Effect of total sleep deprivation on the dimensional complexity of the waking EEG

STUDY OBJECTIVES

Sleep deprivation can affect the waking EEG that may reflect information processing of the brain. We examined the effect of total sleep deprivation (TSD) on nonlinear dynamics of the waking EEG.

DESIGN

Paired-group design.

SETTING

A sleep disorders laboratory in a hospital.

PARTICIPANTS

Twenty healthy male volunteers.

INTERVENTIONS

Waking EEG data were recorded from subjects with eyes closed after (a) an 8-hour night's sleep and (b) TSD for 24 hours. The dimensional complexity (D2), as a nonlinear measure of complexity, of the EEG after a full night sleep were compared with those of the EEG after TSD.

MEASUREMENTS AND RESULTS

The sleep-deprived states had lower D2 values at three channels (P4, O2, and C3) than normal states.

CONCLUSIONS

TSD results in the decrease of complexity in the brain, which may imply sub-optimal information processing of the cerebral cortex. We suggest that the investigation of the relation between nonlinear dynamics of the waking EEG induced by TSD and cognitive performance may offer fruitful clues for understanding the role of sleep and the effects of sleep deprivation on brain function.

Long-term delivery of all-trans-retinoic acid using biodegradable PLLA/PEG-PLLA blended microspheres

All-trans-retinoic acid (atRA) has been proved to be effective against several malignancies in human clinical trials. However, in many patients who were treated with atRA, the cancer relapsed after a brief remission. One reason for such relapse is that atRA is metabolized by specific P450s that are induced in the liver during prolonged atRA treatments. In order to overcome such a drawback of atRA, we prepared biodegradable microspheres to provide continuous release of atRA for a long period of time. These biodegradable microspheres were prepared by poly(L-lactide) (PLLA) and polyethylene glycol (PEG)-PLLA diblock copolymers (PLE) in various blending ratios to control the release rate of atRA. As the PLE content in microsphere was increased, the density of the hydrophilic PEG block of PLE on microsphere surfaces increased and the microspheres were dispersed well in PBS without any surfactants. Various release patterns of atRA were obtained according to PLE and atRA contents in the microspheres. Especially, the pseudo-zero-order release profiles were observed for 5 weeks when the contents of PLE and atRA in the microspheres were above 4 wt.%.

Baryon rapidity loss in relativistic Au + Au collisions

An excitation function of proton rapidity distributions for different centralities is reported from AGS Experiment E917 for Au+Au collisions at 6, 8, and 10.8 GeV/nucleon. The rapidity distributions from peripheral collisions have a valley at midrapidity which smoothly change to distributions that display a broad peak at midrapidity for central collisions. The mean rapidity loss increases with increasing beam energy, whereas the fraction of protons consistent with isotropic emission from a stationary source at midrapidity decreases with increasing beam energy. The data suggest that the stopping is substantially less than complete at these energies.

Seronegative spondyloarthropathy initiated by physical trauma

We undertook this study to demonstrate the pattern of onset and the course of arthritis on the traumatised joint in spondyloarthropathy (SpA) initiated by physical trauma. Among 288 patients with SpA, 12 (4.2%) whose arthropathies were associated with trauma were reviewed retrospectively. There were seven patients with ankylosing spondylitis (AS), three with juvenile onset AS and two undifferentiated SpA. The type of trauma was direct injury to the joint and injuries at other sites, except in spinal surgery, for example. In eight cases the initial evidence of disease was peripheral arthritis. The disease first occurred in traumatised joints in five cases. Only three cases showed recurrent inflammatory episodes in the traumatised joints throughout the disease course. SpA initiated by trauma initially manifested as peripheral arthritis at the traumatised joints in about half of the cases. Inflammatory episodes preferentially involved other joints apart from the traumatised joints throughout the whole course of the disease.

Mixed connective tissue disease associated with skin defects of livedoid vasculitis

A 21-year-old woman who had a 2-year history of mixed connective tissue disease (MCTD) developed rapidly evolving ulcers consistent with livedoid vasculitis (LV) in all distal extremities. She presented clinically with Raynaud's phenomenon, polyarthritis and swollen hands; serologically with high titres of ANA and anti-nRNP; and immunogenetically with HLA-DR4 and HLA-DR53. Although there was initial success in treatment except for the skin defects over the ankles, the patient died from disseminated intravascular coagulation. We suggest that LV may be a poor prognostic manifestation in MCTD.

5-acyloxy-5-hydroxymethyltetrahydro-2-furancarboxylate as a novel template for protein kinase C (PKC) binding

A series of alkyl tetrahydrofuran-2-carboxylates (1-4) bearing a new set of three pharmacophoric groups were tested as protein kinase C (PKC) ligands. The compounds were synthesized from commercially available glycidyl 4-methoxyphenyl ether. The correlation between their binding affinities for PKC-alpha and a conformational fit to phorbol ester indicates they mimic a pharmacophore model comprising the C20-OH, C3-C=O and C9-OH rather than that including the C13-C=O moiety.

Transverse myelitis in a patient with long-standing ankylosing spondylitis

Ankylosing spondylitis is reported to involve not only the joints but other organs as well. Among these extra-articular involvements, uncommon complications associated with nervous system such as single root lesions, compression of the myelum and cauda equina syndrome have also been documented. Here we present a patient with long-standing ankylosing spondylitis who developed spastic paraparesis. Extensive study to find the cause of a spastic paraparesis failed and therefore led to the conclusion that this patient was suffering from transverse myelitis. Similar reports in the past have been attributed to an association with multiple sclerosis; however, we suggest that the findings support the diagnosis of a rare complication of ankylosing spondylitis with an unknown etiology.

Parapharyngeal second branchial cyst manifesting as cranial nerve palsies: MR findings

SUMMARY

We report the MR findings of parapharyngeal branchial cleft cyst manifesting as multiple, lower cranial nerve palsies in a 35-year-old woman. On MR images, a well-marginated cystic mass was detected in the right parapharyngeal space, with displacement of both the right internal carotid artery and the right internal jugular vein on the posterolateral side. The cyst contained a whitish fluid that was slightly hyperintense on T1-weighted images and slightly hypointense to CSF on T2-weighted images. No enhancement on contrast-enhanced T1-weighted images was present. The right side of the tongue showed high signal intensity on T2-weighted images, suggesting denervation.

Bicritical scaling behavior in unidirectionally coupled oscillators

We study the scaling behavior of period doublings in a system of two unidirectionally coupled parametrically forced pendulums near a bicritical point where two critical lines of period-doubling transition to chaos in both subsystems meet. When crossing a bicritical point, a hyperchaotic attractor with two positive Lyapunov exponents appears, i.e., a transition to hyperchaos occurs. Varying the control parameters of the two subsystems, the unidirectionally coupled parametrically forced pendulums exhibit multiple period-doubling transitions to hyperchaos. For each transition to hyperchaos, using both a "residue-matching" renormalization group method and a direct numerical method, we make an analysis of the bicritical scaling behavior. It is thus found that the second response subsystem exhibits a new type of non-Feigenbaum scaling behavior, while the first drive subsystem is in the usual Feigenbaum critical state. The universality of the bicriticality is also examined for several different types of unidirectional couplings.

Expression of Fas and Fas-related molecules in human hepatocellular carcinoma

Many tumor cells, including hepatocellular carcinoma (HCC), express both Fas and its ligand on their surfaces, and it has remained a mystery why such cells do not spontaneously become apoptotic. In the current study, we analyzed the alterations of Fas structure and the expression of Fas and Fas ligand (FasL) and of Fas pathway inhibitors, including soluble Fas (sFas), Fas-associated phosphatase-1 (FAP-1), and bcl-2, in 50 cases of human HCC. Monoallelic loss of the Fas gene, as determined by loss of heterozygosity with intragenic polymorphisms, was observed in 5 of the 34 informative cases (15%), but none of the 50 cases showed Fas gene mutation. Expression of Fas and FasL was detected in 44 (88%) and 50 (100%) cases, respectively. sFas messenger RNA, as analyzed by in situ reverse-transcription polymerase chain reaction was expressed in 42 of the 50 cases (84%), and FAP-1 expression was observed in 40 of the 50 cases (80%). In contrast, none of the 50 cases showed bcl-2 expression. Our results showed that the majority of the HCCs (88%) coexpressed a death receptor, Fas and its cognate ligand, FasL, but all HCCs showed one or more alterations of the Fas pathway molecules known to inhibit Fas-mediated apoptosis. These findings suggest that the expression of sFas and FAP-1 and, in part, loss of Fas expression, rather than Fas gene alteration or bcl-2 expression, may be involved in the Fas resistance of HCC in vivo and that these mechanisms may play important roles in the pathogenesis of human HCC. HUM PATHOL 32:250-256.

Dissociation between plasma adrenocorticotropin and serum cortisol level during the early postoperative period after gastrectomy

We demonstrated the dissociation between plasma adrenocorticotropin (ACTH) and serum cortisol levels during the early recovery period after radical gastrectomy in 9 of 31 patients with gastric adenocarcinoma. Patients with the dissociation between plasma ACTH and serum cortisol levels (DAC) showed a sustained elevation of serum cortisol level on the first or second postoperative day, while the plasma ACTH level returned to its preoperative state. These patients also had more advanced cancers (p < 0.05) and suffered from more postoperative complications (p < 0.05) than those without DAC. In these patients with DAC, serum cortisol and interleukin (IL)-6 levels remained higher on the second postoperative day than in those of the patients without DAC (21.80 +/- 1.57 vs. 13.68 +/- 0.72 microg/dl, p < 0.001, and 74.31 +/- 15.65 vs. 18.75 +/- 3.14 pg/ml, p < 0.001, respectively). On the second postoperative day, serum IL-6 levels showed a significant correlation with serum cortisol levels in all patients (r = 0.511, p < 0.01). These results suggest that the DAC during the early postoperative period after radical gastrectomy is associated with advanced stage of cancer and postoperative complication, and that the increased serum IL-6 level is at least in part responsible for maintaining the elevated serum cortisol.

NO as an autocrine mediator in the apoptosis of activated microglial cells: correlation between activation and apoptosis of microglial cells

Abnormal activation of microglial cells has been implicated in various neurodegenerative diseases. Microglial activation needs to be tightly regulated for physiological maintenance and normal functioning of the central nervous system. Potential mechanisms for the down-regulation of activated microglial cells are the deactivation or elimination of activated cells. We hypothesized that the elimination of activated microglial cells by apoptosis is one of the key mechanisms of auto-regulation of activated microglial cells. To test this hypothesis, we utilized BV-2 mouse microglial cells and rat primary microglial cultures exposed to activating agents such as lipopolysaccharide and interferon-gamma, and investigated a possible correlation between apoptosis and activation of these cells. We found that the activation of microglial cells led to apoptotic death, and the activation state of microglial cells inversely correlated with cell viability. We have also demonstrated that: (i) NO was produced by activated microglial cells in a manner dependent on time and dose of activating agents; (ii) inhibition of NO synthesis by iNOS inhibitor blocked the apoptosis of activated microglial cells; (iii) an exogenous NO donor induced apoptosis of microglial cells; and (iv) inhibition of TNFalpha or FasL using neutralizing antibodies did not affect activation-induced apoptosis of microglial cells. These results indicated that activation of microglial cells leads to the production of NO, which in turn acts as the major mediator of cellular apoptosis in an autocrine fashion. Our work suggests the presence of auto-regulatory mechanism for microglial activation, which may have relevance in the pathogenesis of various neurodegenerative diseases possibly resulting from 'over-activation' of microglial cells.

Association of alpha-2-macroglobulin deletion polymorphism with sporadic Alzheimer's disease in Koreans

Alpha-2-macroglobulin (A2M) deletion polymorphism was recently reported to be associated with Alzheimer's disease (AD) in a way comparable to apolipoprotein E (APOE) polymorphism in a family-based study. However, the association of A2M deletion polymorphism with AD has not been consistently replicated in successive case-controlled studies. In order to evaluate whether this A2M polymorphism is associated with AD in Koreans, we examined the frequencies of the A2M deletion (D) allele and D-bearing genotypes in a group of Koreans composed of 100 sporadic AD patients and 203 control subjects. The frequency of the deletion (D) allele (P=0.046) was significantly different between the total group of AD patients and the controls, although the frequency of the D-bearing genotypes did not attain significance (P=0.078). When the subjects were stratified according to age at onset, there was significant difference in the frequencies of the D allele (P=0.044) and D-bearing genotypes (P=0.041) between late-onset AD patients (> or =65 years) and the controls. However, no significant difference was observed between early-onset AD patients (<65 years) and the control group. Additionally, when we divided the late-onset AD and control subjects by APOE epsilon4 status, the difference of the A2M D allelic frequency was significant only in the APOE epsilon4 negative subjects (P=0.015). In conclusion, our data suggests that the A2M D allele is a modest risk factor for late-onset sporadic AD in Koreans, and the AD risk conferred by the A2M D allele increases in APOE epsilon4 negative subjects.