Evaluation of left ventricular function with cine magnetic resonance four chamber/multiple slice multiple phase sequence

OBJECTIVE

To investigate the value of cine magnetic resonance(MR) in determination of cardiac function by using four chamber/multiple slice multiple phase (4CH/MSMP) sequence.

METHODS

In 18 healthy subjects, several indices of left ventricular function were measured by using cine MR 4CH/MSMP sequence, and the correlation of the results was compared with ultrasound cardiography by t test.

RESULTS

In the measurement of left ventricular short diameter, left ventricular posterior wall thickness, internal ventricular septum thickness, left ventricular end diastolic and end systolic volume, the values of cine MR 4CH/MSMP sequence correlated well with those of echocardiography. The gamma value was between 0.88 and 0.99.

CONCLUSION

The cine MR 4CH/MSMP sequence may be considered an important noninvasive modality for accurate assessment of cardiac function.

[Efficient gene transfer mediated by retrovirus vector in leukemic cells]

OBJECTIVE

To establish an efficient and safe gene transfer system mediated by retrovirus for providing an experimental basis of gene therapy in human leukemia.

METHODS

The retrovirus vector pLXSN, carrying the NeoR, was transferred into amphotropic packaging cell line GP + envAm12 by liposome method or by transduction. Retrovirus with higher titer was used to infect human leukemic cell lines NB4, U937 and THP-1. The efficiency of gene transduction was tesed on colonies formed by K562 cells after gene transduction.

RESULTS

The titer of DOSPER liposome transfected GP + envAm12 pool on NIH3T3 cells was 8.0 x 10(5) CFU/ml while that of producer pool infected with mouse retrovirus was 1.6 x 10(7) CFU/ml. Integration of NeoR into human leukemic cells was confirmed by PCR. By both nested PCR and NeoR rescue assay, no helper virus was found. NeoR gene transfer with the efficiency as high as 93.3 to 100% in K562 cells was verified by semi-nested PCR on the colonies after seven days' culture.

CONCLUSION

The efficiency and safety of the gene transfer system may provide an optimal experimental system in gene therapy for human leukemia.

Higher levels of thymidylate synthase gene expression are observed in pulmonary as compared with hepatic metastases of colorectal adenocarcinoma

PURPOSE

It has been observed previously that the pulmonary metastases of colorectal adenocarcinoma are less responsive to therapy with fluorouracil (FUra) as compared with other sites of metastasis (liver, local). To investigate the basis of this chemoresistance, the levels of thymidylate synthase (TS) mRNA and protein were measured, as TS expression has been shown to be predictive of response to therapy in colorectal cancer.

MATERIALS AND METHODS

Tumors were obtained from 19 patients with metastatic colorectal cancer (12 hepatic and seven pulmonary). TS expression was measured by quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and TS protein levels were measured by Western blotting. The presence of TS amplification was assessed by Southern blotting. Levels of p53 protein were determined using immunohistochemistry.

RESULTS

TS mRNA expression was shown to be significantly higher in the pulmonary metastases (mean TS/beta-actin ratio, 19.7; n = 7) as compared with the hepatic metastases (mean TS/beta-actin ratio, 4.7; n = 11) of colorectal cancer. Lower TS expression was observed in patients with hepatic metastases who had received prior FUra versus patients who had not been treated. High levels of TS expression in some samples was associated with low-level (two to three gene copies) increases in TS gene copy numbers and this was observed more frequently in the pulmonary metastatic samples. The increased gene copy numbers occurred both in samples with wild-type p53 and those with mutant p53 tumor-suppressor gene as determined by immunohistochemistry.

CONCLUSION

High levels of TS enzyme may be the basis of the lack of response of pulmonary metastases to FUra treatment.

[Human tumor xenografted into SCID mice and human immune function reconstitution]

OBJECTIVE

In order to observe (1) The behavior of growth and metastasis of PG and PGPTS7 in SCID mice and human immune function reconstituted mice; (2) The ability of interleukin-6 autosecreted from PGTS7 in enhancing the anti-tumor activity of the peripheral blood lymphocytes (PBL).

METHODS

Xenografting of PG and PGTS7 into the subepithelial space of the SCID mice, and in some of these animals, human PBL were administrated simultaneously into the peritoneal cavities. The latent period, taken rate, growth speed, volume of the grafted tumor, incidences of metastasis in lungs and lymph nodes and serum level of human immunoglobulin of the immunity reconstituted mice were examined.

RESULTS

Although tumor growth had been detected in all the experimental animals, the latent period of grafted PGTS7 was postponed and the volume of tumor mass as well as the incidence of lymph node metastasis all became lower in the immunity reconstituted mice accompanied simultaneously with a higher serum level of human immunoglobulin (HIg).

CONCLUSIONS

(1) The SCID mice are good as an appropriated hosts in studying the behavior of growth and metastasis of PG and PGTS7. (2) IL-6 autosecreted from PGTS7 stimulates the proliferation and promotes the activating of PBL. It seems also able to enhance the liberation of human immunoglobulin: to suppress the growth of tumor cells and to reduced the rate of lymph node metastasis.

Genotoxicity of nitric oxide produced from sodium nitroprusside

Induction of mutation and micronucleus (MN) formation by nitric oxide (NO) was investigated in mammalian cells using sodium nitroprusside (SNP) as a drug donor of NO. Results showed that the concentration of NO2- in the tested solution rose according to time- and concentration-exposure to SNP. The treatment of SNP (0.5-8 micromol/ml with S9 or 2-8 micromol/ml without S9) induced a concentration-dependent increase in the mutation frequency at the gpt gene locus in g12 cells and caused a 13- (-S9) to 25- (+S9) fold increase above the background level at the highest concentration. A statistically significant increase in the number of micronucleated binucleated cells (MNBN) was also observed in treated groups. MNBN per thousand, MN per thousand and the proportion of the multiple micronuleated cells increased in a concentration-dependent manner in the concentration range of SNP (0.5-4 micromol/ml with S9 or 2-8 micromol/ml without S9). Our results indicate that SNP, an NO releasing drug, is genotoxic in g12 cells.

Effect of interleukin-6 on the growth of human lung cancer cell line

OBJECTIVE

To investigate the effect of interleukin-6 (IL-6) on the growth of human lung cancer in vivo as well as in vitro.

METHODS

To examine the mRNA level of IL-6 receptor (IL-6R) in high-metastatic human lung giant cell carcinoma cell line PG by means of reverse transcription polymerase chain reaction (RT-PCR). To assess the existence of IL-6 receptor complex (including IL-6R and gp130) with the treatment of PG cells by use of recombinant human IL-6 (rhIL-6), recombinant human oncostatin M (rhOSM), and recombinant human leukemia inhibitory factor (rhLIF), respectively. To detect the expression of IL-6 by Northern blotting hybridization and bioactive assay. To identify the effect of IL-6 secreted by PG cells by use of IL-6 and IL-6R antisense oligodeoxynucleotides (ODNs), and specific neutralizing antibody to IL-6. To document the influence of IL-6 on PG cells growth in vivo through the strategy of the transfection of expression vector inserted antisense IL-6 cDNA.

RESULTS

RT-PCR analysis revealed that PG cells expressed IL-6R mRNA. Any one of the recombinant cytokine IL-6, OSM and LIF stimulated the growth of PG cells in vitro in a concentration-dependent manner. These results demonstrated IL-6 receptor complex exist in PG cells. At the same time, PG cells expressed IL-6 mRNA and secreted bioactive IL-6. Both IL-6 antisense ODNs and IL-6R ODNs inhibited PG cells proliferation. Treatment of PG cells with IL-6 antibodies reduced the growth of PG cells in vitro. PG cells transfected with IL-6 antisense expression vector showed a decreased growth in nude mice.

CONCLUSION

IL-6 functions as an autocrine growth stimulator for PG cells in vivo as well as in vitro.

Hybrid bilayer membranes in air and water: infrared spectroscopy and neutron reflectivity studies

In this report we describe the fabrication and characterization of a phospholipid/alkanethiol hybrid bilayer membrane in air. The bilayer is formed by the interaction of phospholipid with the hydrophobic surface of a self-assembled alkanethiol monolayer on gold. We have characterized the resulting hybrid bilayer membrane in air using atomic force microscopy, spectroscopic ellipsometry, and reflection-absorption infrared spectroscopy. These analyses indicate that the phospholipid added is one monolayer thick, is continuous, and exhibits molecular order which is similar to that observed for phospholipid/phospholipid model membranes. The hybrid bilayer prepared in air has also been re-introduced to water and characterized using neutron reflectivity and impedance spectroscopy. Impedance data indicate that when moved from air to water, hybrid bilayers exhibit a dielectric constant and thickness that is essentially equivalent to hybrid bilayers prepared in situ by adding phospholipid vesicles to alkanethiol monolayers in water. Neutron scattering from these samples was collected out to a wave vector transfer of 0.25 A(-1), and provided a sensitivity to changes in total layer thickness on the order of 1-2 A. The data confirm that the acyl chain region of the phospholipid layer is consistent with that observed for phospholipid-phospholipid bilayers, but suggest greater hydration of the phospholipid headgroups of HBMs than has been reported in studies of lipid multilayers.

Association of distal chromosome 2q with IDDM in Japanese subjects

An insulin-dependent diabetes mellitus (IDDM)-susceptibility gene (IDDM13) has recently been mapped to a region of distal chromosome 2q, which is syntenic to the region of mouse chromosome 1 containing a murine susceptibility gene for IDDM, Idd5. To determine the contribution of this region to IDDM disease susceptibility further and to narrow the region for positional cloning of susceptibility genes, we have studied the association of distal chromosome 2q with IDDM in the genetically distinct Japanese population. A 137 mobility unit (mu) allele at D2S137 locus was significantly associated with IDDM (odds ratio 1.92, p = 0.0016). Other markers, D2S301 and D2S143, located in the same region were not associated with IDDM, indicating that IDDM13 is in linkage disequilibrium with D2S137, but not with D2S301 or D2S143. The association of D2S137 with IDDM was observed in patients lacking one of two high risk HLA alleles, DQBI*0303 and DQBI*0401, but not in patients with either of these alleles. The frequency of high risk HLA alleles was significantly lower in patients with the susceptible allele at D2S137, suggesting that IDDMI3 contributes to IDDM susceptibility in subjects without high risk genotypes at IDDM1. Demonstration of allelic association of D2S137 with IDDM localizes IDDM13 in the close vicinity (<2 centiMorgans) of D2S137, greatly facilitating fine structure mapping and positional cloning of IDDM13.

Toward the phylogeny of the family Lacertidae: implications from mitochondrial DNA 12S and 16S gene sequences (Reptilia: Squamata)

A phylogeny of the family Lacertidae was derived from mtDNA gene sequence data. Seventeen species, representing 16 currently recognized genera and subgenera, were included in the analysis. A total of 954 bp was obtained and aligned from 12S and 16S partial gene sequences. A preferred tree was selected based on weighted parsimony and functional ingroup and outgroup analyses. Decay analysis, bootstrapping, and permutation tail probability were used to evaluate support for the recovered nodes. The genus Gallotia was resolved as the basal taxon and the sister group of all remaining lacertids. Takydromus branched off next. All African lacertids grouped together and formed a monophyletic clade with the Eurasian genera Eremias and Ophisops. The remaining Eurasian lacertids sequentially branched off near the base of the tree in a "comb-like" fashion. The basal position of Gallotia and the monophyly of African lacertids are consistent with previous hypotheses. The European-origin hypothesis of lacertids is favored, and the distribution of lacertids in Africa is likely a Miocene dispersal event. Most of the extant European lacertids probably arose after the Eocene. The classification of the family needs to be revised.

Formation and crystallization of yeast RNA polymerase II elongation complexes

Minimal templates were devised for the efficient generation of yeast RNA polymerase II transcription elongation complexes. A 33-base pair DNA with a 15-residue dC tail at one 3'-end supported the formation of a complex containing the polymerase paused at nucleotide 11 of the duplex region and an RNA of 14-16 residues. The same template could yield an arrested complex with the enzyme at nucleotide 13-15 and RNA of 15-17 residues. These complexes were stable for at least a week under various conditions and could be resolved by gel electrophoresis or purified by ion exchange chromatography. The purified paused complex formed crystals capable of x-ray diffraction to 3.5 A resolution. The complex remained active in the crystal and, in the presence of nucleoside triphosphates, could efficiently extend the transcript in situ.

The production of recombinant dengue virus E protein using Escherichia coli and Pichia pastoris

The dengue virus envelope protein was expressed as a GST fusion protein using E. coli and P. pastoris as expression hosts. In E. coli the recombinant E protein is expressed initially as a soluble 81 kDa GST fusion protein. Treatment of the fusion protein with thrombin released a 55 kDa protein, which is the expected size for correctly processed, non-glycosylated recombinant E protein. The antiserum from animals immunised with this recombinant E protein was found to specifically recognise the dengue virus E protein in virus-infected cells, thus demonstrating the immunogenic nature of the recombinant E protein. This expression system allowed production of up to 2 mg of purified recombinant E protein from a 1 1 bacterial culture. In contrast, expression of this GST fusion protein in P. pastoris is associated with extensive proteolytic degradation of the recombinant E protein. However, this proteolytic degradation was not observed in the truncated E protein sequences which were expressed. One of these recombinant fusion proteins, GST E401 was secreted into the culture medium at levels of up to 100 microg/l of growth medium.

Interactions among subunits of the oligosaccharyltransferase complex

The mammalian oligosaccharyltransferase (OST) is an oligomeric complex composed of three membrane proteins of the endoplasmic reticulum: ribophorin I (RI), ribophorin II (RII), and OST48. In addition, sequence homology between the Ost2 subunit of the yeast OST complex and Dad1 (defender against apoptotic death) suggests that Dad1 may represent a fourth subunit of the mammalian OST complex. In attempts to elucidate the structural organization of this complex, we have studied the interactions among its subunits. Using the yeast two-hybrid system, we have shown that the luminal domains of RI and RII (RIL and RIIL, respectively) interacted with the luminal domain of OST48 (OST48L), but no direct interaction was observed between RIL and RIIL. These results were confirmed by biochemical assays. Deletion analyses using the yeast two-hybrid system showed that subdomain of RIL or RIIL adjacent to the respective transmembrane domains interacted with OST48L. Of the three equal length subdomains of OST48L, the one at the N terminus and the one next to the transmembrane domain interacted with RIL. None of these three subdomains of OST48L interacted with RIIL. The yeast two-hybrid assay also revealed affinity between the cytoplasmically located N-terminal region of Dad1 and the short cytoplasmic tail of OST48, thus placing Dad1 firmly into the OST complex. In addition, we found a homotypic interaction between the cytoplasmic domains of RI, which may play a role in the formation of the oligomeric array formed by components of the translocation machinery.

The effect of high-dose methylprednisolone on laser-induced retinal injury in primates: an electron microscopic study

BACKGROUND

Previously we reported an ameliorative effect of high-dose methylprednisolone in laser injury to monkey retinas. The ultrastructural modification by methyl-prednisolone has not been examined.

METHODS

Cynomolgus monkeys were given severe (grade III) retinal laser burns and treated with an intravenous megadose of methylprednisolone. Pathologic features of the retinal lesions with or without methylprednisolone treatment were evaluated by light and electron microscopy.

RESULTS

Ultrastructurally, the treated lesions showed rapid recanalization of choriocapillaris; proliferation of retinal pigment epithelium to replace the necrotic and damaged cells, resulting in rapid re-establishment of blood retinal barrier; mild macrophagic activity; and rapid reformation of the outer limiting membrane by Mueller cells.

CONCLUSION

A high dose of methylprednisolone affected the responses of the choriocapillaris, retinal pigment epithelium, photoreceptor cells and Mueller cells to laser injury, showing an overall beneficial effect. These modifications might be ascribed to methylprednisolone's anti-inflammatory action, protection of the microcirculation and anti-lipid peroxidation effect.

An intracellular protein that binds amyloid-beta peptide and mediates neurotoxicity in Alzheimer's disease

Amyloid-beta is a neurotoxic peptide which is implicated in the pathogenesis of Alzheimer's disease. It binds an intracellular polypeptide known as ERAB, thought to be a hydroxysteroid dehydrogenase enzyme, which is expressed in normal tissues, but is overexpressed in neurons affected in Alzheimer's disease. ERAB immunoprecipitates with amyloid-beta, and when cell cultures are exposed to amyloid-beta, ERAB inside the cell is rapidly redistributed to the plasma membrane. The toxic effect of amyloid-beta on these cells is prevented by blocking ERAB and is enhanced by overexpression of ERAB. By interacting with intracellular amyloid-beta, ERAB may therefore contribute to the neuronal dysfunction associated with Alzheimer's disease.

[Molecular evolution of MHC DQA genes. II. Phylogenetic analysis based on nucleotide substitution and SCU bias]

Phylogenetics of 23 alleles at MHC DQA loci in 7 mammalian species was studied based on their nucleotide (NT) substitution and synonymous codon usage (SCU) bias. (1) It was demonstrated that the NT substitution rates are 1.0 x 10(-9) NT/site/yr for exon2 and 1.3 x 10(-9) NT/site/yr for exon2-4 in a large time scale, which is similar to other nuclear genes, while for mouse and rat the rates are nearly twice as high as above mentioned. (2) The DQA locus diversity and their interallelic diversity developed long after the radiation of mammalian 80Mya (million years ago). The bovine counterpart, of, and with the same recent ancestor of ovine DQA2, remains to be discovered. HLA-DQA2 locus split from HLA-DQA1 ancestor at the time between 12 approximately 20 Mya while allele diversity of HLA-DQA1 emerged and developed from 24 Mya to less than 1 Mya. (3) The phylogenetic trees based on SCU divergence reflect the phylogenetics of MHC DQA genes quite well generally in a new respect and reveal that HLA-DQA2 has a distinctive SCU bias different from all other MHC DQA locianalyzed. It indicates that SCU statistics plays an important and unique role in phylogenetic analysis of orthologous genes. The method to estimate the SCU divergence and SCU similarity was improved in this research.

Expression of the integrin alpha5 subunit and its mediated cell adhesion in hepatocellular carcinoma

Tumor invasion and metastasis are complex processes, requiring the ability of tumor cells to interact with proteins of the extracellular matrix through cell-adhesion molecules on the cell surface. Integrins are heterodimeric membrane glycoproteins, consisting of alpha and beta subunits, which enable cells to recognize adhesive substrates in the extracellular matrix. The roles of the integrin alpha5beta1 in tumor invasion are highlighted by finding that some tumor cells have lost or reduced alpha5beta1 expression. It therefore functions as a negative signaling regulator. Expression of alpha5beta1 and its mediation of cell adhesion in hepatocellular carcinoma (HCC) have not been elucidated. In surgical specimens of HCC we found, by immunohistochemistry and Northern blot analysis, that the alpha5-positive rates in cancerous tissues were lower than the corresponding rates in non-cancerous tissues. Reduced expression of the integrin alpha5 occurred more frequently in HCC with more malignant phenotypes, such as poor differentiation, large size (more than 10-cm in diameter), absence of capsule and high invasion. Reverse transcription/polymerase chain reaction, a more sensitive assay, was used to detect the alpha5 mRNA level in LCID20, a highly metastatic model of human HCC, and LCID35, a low-metastasis model. The results showed that integrin alpha5 was negative in the former and positive in the latter. Cell adhesion assays showed the maximal percentage inhibition of anti-alpha5 mAb on SMMC 7721 cell adhesion to fibronectin to be 68.9 +/- 4.9% at the saturation concentrations of each antibody (200 microg/ml). If anti-alpha5 mAb was combined with anti-beta1 mAb, the inhibition was 74.1 +/- 11.1%. It is concluded that reduced expression of the integrin alpha5 subunit is correlated with more malignant phenotypes of human HCC. Any change in the adhesion of hepatocellular carcinoma cells to fibronectin is mainly dependent upon the function of the integrin alpha5beta1.

Epitope analysis of human T-cell response to MSP-1 of Plasmodium falciparum in malaria-nonexposed individuals

BACKGROUND

MSP-1 of Plasmodium falciparum induces strong proliferative T cell responses even in malaria-nonexposed individuals. Epitopes recognized by malaria-nonimmune T cells have not been identified, and immunological mechanisms inducing such T cell responses remain to be uncovered. MSP-1 is a vaccine candidate, and it should be understood whether those epitopes have any roles in MSP-1-mediated protective immunity. The T epitopes-inducing malaria-naive T cell response was analyzed in the hope of understanding the underlying mechanisms.

METHODS

Human T cell lines and clones reactive to MSP-1 of P. falciparum were established from malaria-nonexposed Japanese donors in vitro, and epitope peptides were identified. Sequences of those epitope peptides were compared to unrelated peptides in the data base. One of those peptides was tested for both binding to HLA-DR molecules and inducing proliferative responses of MSP-1-reactive T cells.

RESULTS

There are at least 6 epitopes recognized by malaria-naive T cells under the restriction by HLA-DRB1*1502 or 0802. Important amino acids for the T cell recognition were identified for an MSP-1 peptide. A yeast peptide which shared those residues induced proliferative responses of MSP-1-reactive T cells.

CONCLUSION

We identified T epitopes in the N-terminal region of MSP-1, some of which showed molecular similarities with unrelated environmental antigens, suggesting the presence of cross-reactive T epitopes in MSP-1. Cytokine production in response to those epitopes suggests regulatory functions of those T cells during primary infection with P. falciparum.

[Construction and expression of a functional chimeric murine-human antibody directing against human cross-linked fibrin]

OBJECTIVE

In order to reduce the immunogenicity of the murine antifibrin monoclonal antibody (MAb) SZ-63 to human beings.

METHODS

First of all, the cDNA sequences encoding the constant regions of the murine kappa light chain and gamma 1 heavy chain in the SZ-63 MAb were substituted with the corresponding human genomic sequences. Then the constructed MAb was cloned separately into two selectable expression vectors, and the latter were transfected into mouse myeloma cells (SP2/0) one by one.

RESULTS

ELISA, Western blot and competition experiment results showed that there was 0.8 approximately 1.0 mg/L of chimeric 63 IgG in the conditioned medium of selected cell lines, and the expressed IgG had higher antifibrin D-Dimer capability than that of the original MAb.

CONCLUSION

The expressed chimeric antibody can be used as a targeting agent for thrombus imaging and treatment.

Expression of the dengue virus structural proteins in Pichia pastoris leads to the generation of virus-like particles

We have expressed cDNA encoding the dengue virus structural proteins in Pichia pastoris by chromosomal integration of an expression cassette containing the dengue virus structural genes (CprME). The yeast recombinant E protein migrated during SDS-PAGE as a 65 kDa protein when analysed by Western blotting and radioimmunoprecipitation, which is the expected molecular mass for correctly processed and glycosylated E protein. Treatment with endoglycosidases showed that the recombinant E protein was modified by the addition of short mannose chains. The E protein migrated with a buoyant density of 1.13 g/cm3 when analysed using sucrose density gradient centrifugation. Spherical structures with an average diameter of 30 nm, whose morphology resembles dengue virions, were observed in the purified fractions using transmission electron microscopy. Furthermore, the virus-like particles were immunogenic in animals and were able to induce neutralizing antibodies. This is the first report that expression of the structural genes of a flavivirus in yeast is able to generate particulate structures that resemble virions.

[The inhibitory effect of antisense interleukin-6 on the growth of human lung carcinoma cells in vivo]

OBJECTIVE

Interleukin-6 (IL-6) has previously been implicated as a potential positive autocrine regulator of a human lung carcinoma cell lince PG. The purpose of the present study is to further evaluate the role of IL-6 in PG cells in vivo.

METHODS

An antisense expression vector for IL-6 was constructed and introduced into PG cells. Antisense mRNA of IL-6 was detected by RNA-RNA dot blotting analysis. The production of bioactive IL-6 was measured by bioassay method. To determine the effect of antisense IL-6 cDNA on tumorigenicity, PG cells were inoculated subcutaneously into nude mice.

RESULTS

Four transfectants, PGTAS1, PGTAS6, PGTAS8, PGTAS9, could express IL-6 antisense mRNA and secret decreased bioactive IL-6. The growth rate of 4 transfectants revealed was reduced in vitro. Comparing with the mice injected with the control PGTneo cells, the latent period of the mice inoculated with PGTAS6, PGTAS8, PGTAS9 cells was significantly increased, and the growth rate of the tumors was obviously decreased. The tumor size was markedly smaller. There was a negative correlation between the growth-inhibiting effect of IL-6 antisense gene and the amount of IL-6 secretion.

CONCLUSION

These results indicate that IL-6 can function as an autocrine stimulator for PG cells in vivo as well as in vitro.

bFGF induces BCK promoter-driven expression in muscle via increased binding of a nuclear protein

Changes in gene expression occurring during skeletal muscle differentiation are exemplified by downregulation of brain creatine kinase (BCK) and induction of muscle creatine kinase (MCK). Although both are transcriptionally regulated, there appears to be no transcription factor-element overlap, suggesting that their coordinate expression results from culture medium-related influences. Basic fibroblast growth factor (bFGF) prevents myogenesis and represses MCK expression by inhibiting transcriptional activation. It was hypothesized that bFGF similarly influenced BCK by inducing its expression. Accordingly, BCK promoter constructs were transiently transfected into C2C12 cells and, after a switch to differentiation medium, were treated with bFGF, bFGF plus herbimycin, adenosine 3',5'-cyclic monophosphate (cAMP), or phorbol 12-myristate 13-acetate (PMA). Analyses demonstrated that bFGF responsiveness was contained within a 33-base pair element. Electromobility shift assays showed that bFGF induction increased the abundance of the nuclear factor binding the element. Both effects were prevented by herbimycin. Neither cAMP nor PMA specifically induced the construct containing the bFGF-responsive element. The induced factor required phosphorylation to bind, implying that bFGF-mediated increases in binding may be due to transcription factor phosphorylation.

[Molecular evolution of MHC DQA genes. I. The maintenance of interallelic divergence and the influence of GC content on gene structure]

The analyses of the proportion of synonymous and missense nucleotide substitution (PS and PN) in different exons, antigen recognition sites (ARS) and non-ARS of EN2 (NAEN2) of 23 alleles at MHC DQA loci in 7 mammal species gave rise to the following findings. (1) PN was about twice as much as PS in ARS among the alleles at DQA1 of any given species, i.e. 7 alleles at HLA-DQA1 or 8 alleles at IaAa this accords with overdominant selection; (2) PS showed more or less the same as PN in ARS among different loci (DQA1 or DQA2 in different species, or DQA1 and DQA2 in one species) or NAEN2 of all comparative pairs, this conforms the expectation of neutral selection; (3) In exon4 and exon3, not only was the substitution proportion extremely low, but also PS was much higher than PN (the ratio PS over PN is 19.5 in alleles at IaAa of mouse and 4 among alleles at different loci), this coincides obviously with purification selection. The analysis of GC content of MHC DQA showed that its peaks were in the regions corresponding to the middle bulks of some domains, that the highest and constant level was in exon4 and that GC content in the third codon position (GC III content) associates inversely with PS. These results indicate that the specified maintenance mechanisms of interallelic diversity relevant to their functions exist in given exons corresponding to some domains of the same MHC DQA locus and GC III content is an important factor in keeping the structure and function of gene under selection constraint. The method for estimating nucleotide substitution proportion was modified.

Amyloid-beta peptide-receptor for advanced glycation endproduct interaction elicits neuronal expression of macrophage-colony stimulating factor: a proinflammatory pathway in Alzheimer disease

In Alzheimer disease (AD), neurons are thought to be subjected to the deleterious cytotoxic effects of activated microglia. We demonstrate that binding of amyloid-beta peptide (Abeta) to neuronal Receptor for Advanced Glycation Endproduct (RAGE), a cell surface receptor for Abeta, induces macrophage-colony stimulating factor (M-CSF) by an oxidant sensitive, nuclear factor kappaB-dependent pathway. AD brain shows increased neuronal expression of M-CSF in proximity to Abeta deposits, and in cerebrospinal fluid from AD patients there was approximately 5-fold increased M-CSF antigen (P < 0.01), compared with age-matched controls. M-CSF released by Abeta-stimulated neurons interacts with its cognate receptor, c-fms, on microglia, thereby triggering chemotaxis, cell proliferation, increased expression of the macrophage scavenger receptor and apolipoprotein E, and enhanced survival of microglia exposed to Abeta, consistent with pathologic findings in AD. These data delineate an inflammatory pathway triggered by engagement of Abeta on neuronal RAGE. We suggest that M-CSF, thus generated, contributes to the pathogenesis of AD, and that M-CSF in cerebrospinal fluid might provide a means for monitoring neuronal perturbation at an early stage in AD.