Highly potent, orally active novel small-molecule HPK1 inhibitor DS21150768 induces anti-tumor responses in multiple syngeneic tumor mouse models

Augmenting T-cell activity is a promising approach to enhance the efficacy of cancer immunotherapy treatment. Hematopoietic progenitor kinase 1 (HPK1) is predominantly expressed in immune cells and negatively regulates T-cell receptor signaling. It is reported that inhibition of the kinase function of HPK1 results in tumor growth suppression by enhancing cancer immunity. Thus, developing HPK1 inhibitors has attracted considerable attention as a future cancer immunotherapy approach. However, despite recent progress in HPK1 biology and pharmacology, various challenges still remain, such as developing HPK1 inhibitors with favorable pharmacological profiles and identifying tumor characteristics that can be applied to define susceptibility to HPK1 inhibition. Here, we present the identification and pharmacological evaluation of DS21150768, a potent small-molecule HPK1 inhibitor with a novel chemical scaffold. DS21150768 shows remarkable inhibition of HPK1 kinase activity, and in vitro studies demonstrated its potent activity to enhance T-cell function. DS21150768 is orally bioavailable and shows sustained plasma exposure, which leads to enhanced cytokine responses in vivo. We conducted a comparison of the anti-tumor efficacy of DS21150768 alone or in combination with anti-PD-1 antibody in 12 different mouse cancer cell models, and observed that the treatments suppressed tumor growth in multiple models. Furthermore, Gene Set Enrichment Analysis demonstrated significant enrichment of immune-related gene signatures in the tumor models responsive to DS21150768 treatment. Our results provide a path forward for the future development of HPK1 inhibitors and fundamental insights into biomarkers of HPK1-targeted therapy.

Dietary intake of antioxidant vitamins and risk of stroke: the Japan Public Health Center-based Prospective Study

BACKGROUND/OBJECTIVES

Epidemiologic evidence on the relationship between antioxidant vitamin intake and stroke is limited. We aimed to investigate the association between dietary intake of antioxidant vitamins and the incidence of total stroke and ischemic stroke.

SUBJECTS/METHODS

The subjects were 82 044 Japanese men and women aged 45-74 years under the Japan Public Health Center-based Prospective Cohort Study. Between 1995 and 1997, dietary assessment was done using a food frequency questionnaire. During 983 857 person-years of follow-up until the end of 2009 we documented 3541 incident total strokes and 2138 ischemic strokes.

RESULTS

Dietary intakes of α-carotene, β-carotene, α-tocopherol and vitamin C were not inversely associated with the incidence of total stroke and ischemic stroke adjustment for cardiovascular risk factors and selected lifestyle variables. When stratified by current smoking status, the inverse association between dietary vitamin C intake and incidence of total stroke observed among non-smokers but not smokers, with respective multivariable hazard ratios for the highest versus lowest quintiles of vitamin C of 0.81 (95% confidence interval (CI), 0.68-0.96; P-trend=0.03) among non-smokers; and 1.03 (0.84-1.25; P-trend=0.55) among smokers. As for ischemic stroke, the corresponding multivariable hazard ratios were 0.76 (0.60-0.96; P-trend=0.02) among non-smokers; and 1.00 (0.78-1.28; P-trend=0.61) among smokers.

CONCLUSIONS

Dietary vitamin C intake was inversely associated with the incidence of total stroke and ischemic stroke among non-smokers.

NMR analysis of tertiary interactions in HDV ribozymes

Three variants of minimized hepatitis delta virus (HDV) RNA ribozyme systems designed on the basis of the "pseudoknot" model were synthesized and their tertiary interactions were analyzed by NMR spectroscopy. Rz-1 is a cis-acting ribozyme system (the cleaved form, 56-mer) in which stem IV is deleted from the active domain of genomic HDV RNA. Rz-1 was uniformly labeled with stable isotopes, 13C and 15N. Rz-2 is a trans-acting ribozyme system (substrate: 8-mer, the cytidine residue at the cleavage site is replaced by 2'-O-methylcytidine; enzyme: 16-mer plus 35-mer). Rz-2 was partially labeled with stable isotopes in guanosine residues of enzyme 35mer. Rz-4 is a trans-acting ribozyme system (substrate: 8mer, the cytidine residue at the cleavage site is replaced by 2'-O-methylcytidine; enzyme 53mer) which was designed by Perrotta and Been. Rz-4 has the same sequence and an extra loop closing stem IV. From 2D-NOESY and 2D-HSQC (except for Rz-4) spectra, it was suggested each ribozyme forms "pseudoknot" type structure in solution. Additionally, it was found that G38 of Rz-1, G28 and G29 of Rz-2 and Rz-4 form base-pairs. These novel base-pairs are observed in the crystal structure of a modified genomic HDV RNA. From temperature change experiment of Rz-2, the imino proton signal of G28 disappeared at 50 degrees C earlier than the other corresponding signals. Upon MgCl2 titration of Rz-2, this signal showed the largest shift.

NMR study of a novel RNA quadruplex structure

The structure of an RNA oligomer, r (GGAGGUUUUGGAGG) (R14-2) whose G-G steps are separated by adenine and uracil residues has been investigated by NMR. In the presence of 20 mM K+, a novel dimeric multiplex architecture is adopted by two strands of R14-2. In each strand a UUUU loop and two A residues connect four parallel G-G steps that pair-align into two tetrads. One of the tetrads is further pair-aligned by two A residues through the sheared mismatch and a novel hexad is subsequently formed. Two hexads coming from two different strands stack to make a dimeric multiplex. All of the guanosine and adenosine residues take an anti conformation.

Design and properties of trans-acting HDV ribozymes with extended substrate recognition regions

We constructed a new type of trans-acting HDV ribozyme which is based on the antigenomic RNA sequence and has an additional binding site to form an extra stem (P5) of 7 base-pairs introduced in the J1/2 region between P1 and P2 stems. A substrate RNA containing the two binding sequences was specifically cleaved while no selectivity was observed in the case of the wild-type ribozyme with only one binding site. Mutation to produce two mismatch base-pairs in the central part of the P5 stem abolished the specific cleavage.

New quadruplex structure of GGA triplet repeat DNA--an intramolecular quadruplex composed of a G:G:G:G tetrad and G(:A):G(:A):G(:A):G heptad, and its dimerization

The structure of d(GGAGGAGGAGGA) containing four tandem repeats of a GGA triplet sequence has been determined under physiological K+ conditions by NMR. d(GGAGGAGGAGGA) folds into an intramolecular quadruplex composed of a G:G:G:G tetrad and a G(:A):G(:A):G(:A):G heptad. Four G-G segments of d(GGAGGAGGAGGA) are aligned parallel to each other due to seven successive turns of the main chain at each of the GGA and GAGG segments. Two quadruplexes form a dimer stabilized through a stacking interaction between the heptads of the two quadruplexes. On the basis of these results, the biological implications of naturally occurring GGA triplet repeat DNA are discussed.

An intramolecular quadruplex of (GGA)(4) triplet repeat DNA with a G:G:G:G tetrad and a G(:A):G(:A):G(:A):G heptad, and its dimeric interaction

The structure of d(GGAGGAGGAGGA) containing four tandem repeats of a GGA triplet sequence has been determined under physiological K(+) conditions. d(GGAGGAGGAGGA) folds into an intramolecular quadruplex composed of a G:G:G:G tetrad and a G(:A):G(:A):G(:A):G heptad. Four G-G segments of d(GGAGGAGGAGGA) are aligned parallel with each other due to six successive turns of the main chain at each of the GGA and GAGG segments. Two quadruplexes form a dimer stabilized through a stacking interaction between the heptads of the two quadruplexes. Comparison of the structure of d(GGAGGAGGAGGA) with the reported structure of d(GGAGGAN) (N=G or T) containing two tandem repeats of the GGA triplet revealed that although the two structures resemble each other to some extent, the extension of the repeats of the GGA triplet leads to distinct structural differences: intramolecular quadruplex for 12-mer versus intermolecular quadruplex for 7-mer; heptad versus hexad in the quadruplex; and three sheared G:A base-pairs versus two sheared G:A base-pairs plus one A:A base-pair per quadruplex. It was also suggested that d(GGAGGAGGAGGA) forms a similar quadruplex under low salt concentration conditions. This is in contrast to the case of d(GGAGGAN) (N=G or T), which forms a duplex under low salt concentration conditions. On the basis of these results, the structure of naturally occurring GGA triplet repeat DNA is discussed.

Polypeptide synthesis using an expressed peptide as a building block for condensation with a peptide thioester: application to the synthesis of phosphorylated p21Max protein(1-101)

An expressed peptide proved to be useful as a building block for the synthesis of a polypeptide via the thioester method. A partially protected peptide segment, for use as a C-terminal building block, could be prepared from a recombinant protein; its N-terminal amino acid residue was transaminated to an alpha-oxoacyl group, the side-chain amino groups were then protected with t-butoxycarbonyl (Boc) groups, and. finally, the alpha-oxoacyl group was removed. On the other hand, an O-phosphoserine-containing peptide thioester was synthesized via a solid-phase method using Boc chemistry. These building blocks were then condensed in the presence of silver ions and an active ester component. During the condensation, epimerization at the condensation site could be suppressed by the use of N,N-dimthylformamide (DMF) as a solvent. Using this strategy, a phosphorylated partial peptide of the p21Max protein, [Ser(PO3H2)2.11]-p21Max(1-101), was successfully synthesized.

Structure of the C-terminal RNA-binding domain of hnRNP D0 (AUF1), its interactions with RNA and DNA, and change in backbone dynamics upon complex formation with DNA

Heterogeneous nuclear ribonucleoprotein (hnRNP) D0 has two ribonucleoprotein (RNP) -type RNA-binding domains (RBDs), each of which can specifically bind to the UUAG-sequence. hnRNP D0 also binds specifically to single-stranded d(TTAGGG)(n), the human telomeric DNA repeat. We have already reported the structure and interactions with RNA of the N-terminal RBD (RBD1). Here, the structure of the C-terminal RBD (RBD2) determined by NMR is presented. It folds into a compact alpha beta structure comprising an antiparallel beta-sheet packed against two alpha-helices, which is characteristic of RNP-type RBDs. In addition to the four beta-strands commonly found in RNP-type RBDs, an extra beta-strand, termed beta 4(-), was found just before the fourth beta-strand, yielding a five-stranded beta-sheet. Candidate residues of RBD2 involved in the interactions with RNA were identified by chemical shift perturbation analysis. Perturbation was detected on the beta-sheet side, not on the opposite alpha-helix side, as observed for RBD1. It is notable that the beta 4(-) to beta 4 region of RBD2 is involved in the interactions in contrast to the case of RBD1. The chemical shift perturbation analysis also showed that RBD2 interacts with DNA in essentially the same way as with RNA. Changes in the backbone dynamics upon complex formation with DNA were examined by means of model free analysis of relaxation data. In free RBD2, the beta 4(-) to beta 4 region exhibits slow conformational exchange on the milli- to microsecond time scale. The exchange is quenched upon complex formation. The flexibility of free RBD2 may be utilized in the recognition process by allowing different conformational states to be accessed and facilitating induced fit. Additionally, faster flexibility on the nano- to picosecond time scale was observed for loop 3 located between beta 2 and beta 3 in free RBD2, which is retained by the complex as well.

Functional magnetic resonance imaging-controlled neuronavigator-guided brain surgery: a case report

The effectiveness of functional magnetic resonance imaging (f-MRI)-controlled and navigator-guided brain surgery for a patient with a recurrent astrocytoma is demonstrated. Preoperative f-MRI was performed in order to identify the motor area and ensure that the tumour was in the left prefrontal area. A more aggressive operation was planned for the recurrent tumour. The f-MRI data were input to the MKM navigation system and during the operation the contours of the tumour and motor area were visualised b y the microscope of the navigation system. The tumour and surrounding gliotic brain tissue were removed completely. The diagnosis was a grade III astrocytoma. The combination of the navigation system and f-MRI was useful for preoperative design of the surgical strategy, and tumour orientation during the operation, enabling aggressive surgery to be performed without functional deficits ensuing.

Structural study of an RNA aptamer for a Tat protein complexed with ligands

An RNA aptamer for an HIV Tat protein has been isolated by the in vitro SELEX method. The RNA aptamer binds to the Tat protein 50-100 times more strongly than native TAR RNA does. Here, we have investigated the structure of the RNA aptamer complexed with ligands, partial peptide fragments of the Tat protein or argininamide, by multidimensional 1H/13C/15N NMR. It is strongly suggested that two U:A:U base triples are formed in the RNA aptamer upon binding of ligands. Specific hydrogen bonds between arginine side chains of ligands and guanine bases located adjacent to the base triples are identified. On the basis of many intramolecular and intermolecular NOEs, a structural model of the complex has been constructed.

Design and NMR analysis of HDV ribozymes for structural investigation

Three variants of minimized hepatitis delta virus (HDV) RNA ribozyme systems (Rz-1 to approximately Rz-3) (Fig. 1) were designed on the basis of the "pseudoknot" structure model and synthesized. Rz-1 is a cis-acting ribozyme system (a cleaved form, 56-mer) in which stem IV is deleted from the active domain of genomic HDV RNA. Rz-1 was uniformly labeled with stable isotopes, 13C and 15N. The 2D-NOESY and 2D-HSQC data for Rz-1 suggest that Rz-1 forms the pseudoknot structure and G38 which is opposite to the cleavage site makes a base-pair. Rz-2 is a trans-acting ribozyme system which consists of three RNA oligomer strands (substrate: 8-mer, the cytidine residue at the cleavage site is replaced by 2'-O-methylcytidine; enzyme: 16-mer plus 35-mer). Rz-3 is a ribozyme in which the three RNA strands of Rz-2 are connected. It turns out that Rz-3 forms an inactive structure with low cleavage activity (k(obs) = 0.009) and final cleavage yield (6%). Rz-3 has the highest cleavage activity at pH 5.5. The optimal activity at acidic pH is similar to that of the wild type ribozyme. We also synthesized and examined the activity and structure of Rz-4 (designed by Perrotta and Been) which consists of two RNA strands (1).

Structure, backbone dynamics and interactions with RNA of the C-terminal RNA-binding domain of a mouse neural RNA-binding protein, Musashi1

Musashi1 is an RNA-binding protein abundantly expressed in the developing mouse central nervous system. Its restricted expression in neural precursor cells suggests that it is involved in the regulation of asymmetric cell division. Musashi1 contains two ribonucleoprotein (RNP)-type RNA-binding domains (RBDs), RBD1 and RBD2. Our previous studies showed that RBD1 alone binds to RNA, while the binding of RBD2 is not detected under the same conditions. Joining of RBD2 to RBD1, however, increases the affinity to greater than that of RBD1 alone, indicating that RBD2 contributes to RNA-binding. We have determined the three-dimensional solution structure of the C-terminal RBD (RBD2) of Musashi1 by NMR. It folds into a compact alpha beta structure comprising a four-stranded antiparallel beta-sheet packed against two alpha-helices, which is characteristic of RNP-type RBDs. Special structural features of RBD2 include a beta-bulge in beta2 and a shallow twist of the beta-sheet. The smaller 1H-15N nuclear Overhauser enhancement values for the residues of loop 3 between beta2 and beta3 suggest that this loop is flexible in the time-scale of nano- to picosecond order. The smaller 15N T2 values for the residues around the border between alpha2 and the following loop (loop 5) suggest this region undergoes conformational exchange in the milli- to microsecond time-scale. Chemical shift perturbation analysis indicated that RBD2 binds to an RNA oligomer obtained by in vitro selection under the conditions for NMR measurements, and thus the nature of the weak RNA-binding of RBD2 was successfully characterized by NMR, which is otherwise difficult to assess. Mainly the residues of the surface composed of the four-stranded beta-sheet, loops and C-terminal region are involved in the interaction. The appearance of side-chain NH proton resonances of arginine residues of loop 3 and imino proton resonances of RNA bases upon complex formation suggests the formation of intermolecular hydrogen bonds. The structural arrangement of the rings of the conserved aromatic residues of beta2 and beta3 is suitable for stacking interaction with RNA bases, known to be one of the major protein-RNA interactions, but a survey of the perturbation data suggested that the stacking interaction is not ideally achieved in the complex, which may be related to the weaker RNA-binding of RBD2.

Structure and interactions with RNA of the N-terminal UUAG-specific RNA-binding domain of hnRNP D0

Heterogeneous nuclear ribonucleoprotein (hnRNP) D0 has two ribonucleoprotein (RNP)-type RNA-binding domains (RBDs), each of which can bind solely to the UUAG sequence specifically. The structure of the N-terminal RBD (RBD1) determined by NMR is presented here. It folds into a compact alphabeta structure comprising a four-stranded antiparallel beta-sheet packed against two alpha-helices, which is characteristic of the RNP-type RBDs. Special structural features of RBD1 include N-capping boxes for both alpha-helices, a beta-bulge in the second beta-strand, and an additional short antiparallel beta-sheet coupled with a beta-turn-like structure in a loop. Two hydrogen bonds which restrict the positions of loops were identified. Backbone resonance assignments for RBD1 complexed with r(UUAGGG) revealed that the overall folding is maintained in the complex. The candidate residues involved in the interactions with RNA were identified by chemical shift perturbation analysis. They are located in the central and peripheral regions of the RNA-binding surface composed of the four-stranded beta-sheet, loops, and the C-terminal region. It is suggested that non-specific interactions with RNA are performed by the residues in the central region of the RNA-binding surface, while specific interactions are performed by those in the peripheral regions. It was also found that RBD1 has the ability to inhibit the formation of the quadruplex structure.

A'-form RNA double helix in the single crystal structure of r(UGAGCUUCGGCUC)

Here we demonstrate the presence of the A'-RNA conformation using the single crystal structure of a tridecamer: r(UGAGCUUCGGCUC). The average A'-RNA conformation deduced from X-ray fiber diffraction data had only been available previously, but now the presence of the A'-RNA conformation has been found in a single crystal structure for the first time. Statistical analysis showed that the A'-RNA conformation is distinguishable from the A-RNA conformation in a plot of the major groove width against the base pair inclination angle. The major groove of the A'-RNA conformation is wide enough to accommodate a protein or peptide while that of the A-RNA conformation is too narrow to do so. The presence of the A'-RNA conformation is significant for protein-RNA interaction.

Temporal and spatial profile of apoptotic cell death in transient intracerebral mass lesion of the rat

Apoptosis is involved in the pathogenesis of cerebral ischemia. Previous studies have confirmed that the brain surrounding an intracerebral hematoma develops ischemia. We investigated the number and distribution of cells exhibiting DNA fragmentation with apoptotic morphology in the transient intracerebral mass lesion to determine whether apoptosis contributed to the lesion progress after intracerebral hemorrhage (ICH). Transient intracerebral mass was created by inflation of a microballoon for 10 min (group A) or 2 h (group B) in the caudoputamen in rats, and brains were examined 1, 3, 6, 24, and 48 h after microballoon deflation. The lesion volume was calculated using parallel coronal sections with cresyl violet staining. Terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine (dUTP)-biotin nick end labeling (TUNEL) was used to detect cells undergoing DNA fragmentation. Immunohistochemistry for Fas antigen was also done to ascertain molecular mechanisms of apoptosis. Histological examination of hematoxylin and eosin-stained sections showed the typical appearance of neuronal necrosis in the caudoputaminal lesion. Lesion volume in the caudoputamen gradually increased as time advanced from 1 to 48 h. Cells stained heavily by TUNEL with apoptotic morphology were detected in the lesion, but not in the inner boundary zone of the lesion. The number of these cells significantly increased from 6 to 24 h in each experimental group (p < 0.05). The cells with positive immunoreactivity for Fas antigen was prominently observed in the lesion at 6 h. The distribution of apoptotic cells and the rapid increase in the number of apoptotic cells after 24 h propose that apoptotic cell death may contribute to lesion core formation but not to gradual development of the lesion.

Seroepidemiologic studies of hepatitis C virus infection in a population of Okayama Prefecture screened for liver disease

To better understand the spread of hepatitis C virus (HCV) infection, we studied the association of HCV infection with similarly transmissible hepatitis B virus (HBV) infection and with hepatitis A virus (HAV) infection, which is supposed to be related to a nosocomial transmission of HCV. This was done by studying the presence or absence of antibodies to these viruses, as well as hepatitis B surface antigen, in a population of 1,398 inhabitants with abnormal liver function tests or history of liver disease and/or blood transfusion. This group was drawn from a group of 7,905 examinees screened for liver disease in 26 districts of Okayama prefecture, Japan. The prevalence of antibody-positive cases increased with age for those viruses. Small but significantly increased odds ratios were obtained among anti-HCV antibodies (HCVAb), anti-hepatitis B core antibodies (HBcAb) and anti-hepatitis A antibodies (HAVAb). After adjusting odds ratios by logistic regression analysis, a significant association was present only between HCVAb and HBcAb. The distribution of age-adjusted prevalences (AAP) of HCVAb in 26 districts was significantly wider than those of HBcAb or HAVAb. The district-based AAP of HCVAb, but not of HBcAb and HAVAb, correlated significantly with the district-based prevalence of infectious hepatitis having a tendency of chronicity reported in 1953-1955. Adjusted odds ratios calculated by logistic regression analysis of the virus markers showed that HCVAb was significantly associated with a past history of blood transfusion. Thus, the spread of HCV infection is speculated to have been triggered by blood transfusion, particularly from paid donors initially, followed by transmission by nosocomial or close person-to-person contact.

Apoptotic cell death induced by local brain hyperthermia in a rat glioma model

Hyperthermia has been shown to inhibit glioma growth both in vitro and in vivo, and has been reported to induce apoptosis of a variety of cells. We investigated the role of apoptosis in tumor cell death following hyperthermia in a rat glioma model representing human glioblastoma. Apoptotic cell death was evaluated by terminal deoxyribonucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) and hematoxylin and eosin (H & E) staining. We also examined c-Jun expression immunohistochemically. Apoptotic cell death in rat brain tumors that grew after implantation of C6 glioma cells showed regional differences. In all rats, apoptotic cells, characterized by extreme chromatin condensation and fragmented nuclei with apoptotic bodies in H & E-stained sections, were observed in the gliomas' necrotic cores. TUNEL-positive cells were observed in the border zones between necrotic and vital tumor cells. Before hyperthermia, TUNEL-positive cells were sporadically distributed in the vital tumor tissue. After hyperthermia, the number of TUNEL-positive cells in the peripheral region of the tumor mass increased significantly, reached a peak after 6 h and returned to the basal level within 24 h (P < 0.01). C-Jun protein immunoreactivity was not observed in the cells at the tumor periphery. These data indicate that significantly apoptotic cell death unrelated to c-Jun expression occurs after hyperthermia, and that this form of cell death may be the mechanism of tumor regression following hyperthermia treatment of intracranial gliomas.

Two metal-binding sites in a lead ribozyme bound to competitively by Pb2+ and Mg2+--induced structural changes as revealed by NMR

We reported recently that a lead ribozyme with modified bases cleaved at an additional site at high Pb2+ concentrations (>0.1 mM), and that the cleavage at a canonical site was enhanced nearly fourfold at the optimum combination of Pb2+ and Mg2+ concentrations [Kim, M. H., Katahira, M., Sugiyama, T. & Uesugi, S. (1997) J. Biochem. (Tokyo) 122, 1062-1067]. Here we have identified two metal-binding sites (sites 1 and 2) of the lead ribozyme at the residue level by NMR. Both sites are located in an asymmetric internal loop of the lead ribozyme. Site 1 is composed of residues of an enzyme strand and site 2 of residues of a substrate strand. The two sites are bound to competitively by Pb2+ and Mg2+. It was revealed that at certain Pb2+ and Mg2+ concentrations, site 1 is occupied by Pb2+ and site 2 is occupied by Mg2+. The dependency of the cleavage at the canonical and other sites on the Pb2+ and Mg2+ concentrations is interpreted by considering the species of metal ions bound to the two sites. It is suggested that the addition of the two metal ions produces similar and different effects on the structure of the lead ribozyme, and the two metal ions have a synergistic effect on the structure.

Serum alpha-fetoprotein levels in healthy Japanese adults

With advances in lectin affinity electrophoresis of alpha-fetoprotein (AFP), the detection of significant changes in serum AFP at low levels in cirrhotics has become important for early detection of hepatocellular carcinoma. Serum AFP levels of 616 healthy individuals without abnormal liver function tests or virus markers of hepatitis B and C were determined by enzyme immunoassay with IMx-AFP Dainapack using automated IMx apparatus set at twice the ordinary sensitivity and compared with those of 241 individuals with abnormal liver function tests and/or positive hepatitis virus markers. The coefficient of variation in this assay was less than 10% at AFP levels as low as 0.2 ng/ml with a lower detection limit of 0.1 ng/ml. The AFP level of healthy population showed a Gaussian distribution curve after logarithmic transformation with a median and 2.5-97.5 percentile reference range of 2.2 (0.6-5.6) ng/ml. There was no significant difference in the AFP level between males and females. Individuals with abnormal liver function tests alone showed no significant increase in serum AFP unless they were associated with positive hepatitis virus markers.

The structures of nucleic acids composed exclusively of non-standard base pairs

We have reported that d(GGAGGAA) forms a new type of quadruplex in the presence of K+. Here we report that in the absence of K+ it forms another kind of new structure composed of non-standard base pairs exclusively. The structure is neither a quadruplex nor a hairpin. The structure gives three clear imino proton signals of G at 10.0, 13.0 and 13.8 ppm, indicating the formation of G:A and/or G:G base pairs. The two signals at 13.0 and 13.8 ppm indicate that there are two base pairs in which the imino protons of G are hydrogen bonded. All residues take anti conformation, which imposes the restriction on the combination of a mutual direction of strands and types of base pairs. Phosphorus signals of the second and fifth residues appear at higher field, while that of the seventh residue at lower field, when compared with those of A and B form structures, suggesting deviations of a backbone conformation from the standard one. Replacement of the second or fifth G by I results in destabilization of the structure, which implies the involvement of amino groups of these residues in base pairing. On the basis of these results, the structure of d(GGAGGAA) is discussed.

Structure-activity correlation for an HDV ribozyme composed of three RNA strands

Hepatitis delta virus (HDV) RNA ribozyme system which consists of three RNA oligomer strands (substrate 8-mer; enzyme 16-mer plus 35-mer, Fig. 1) was designed. Effects of Mg2+ concentration on the pseudo first-order rate constant (kobs) of RNA cleavage reaction and on conformation of ribozyme complex were examined. The secondary structure of the complex was also analyzed by limited digestion with ribonucleases. The kobs and CD data were analyzed by curve-fitting analysis using equations derived for two-Mg2+ and three-Mg2+ ion binding models. The result revealed that a three-Mg2+ binding model can explain the Mg(2+)-concentration-dependent changes of both conformation and activity of the HDV ribozyme.

Structural characterization of a DNA duplex modeled on a DNA:RNA hybrid of the polypurine tract recognized by a reverse transcriptase

The structure of d(TTAAAAGAAAAGGG):d(CCCTTTTCTTTTAA) has been characterized by NMR. The minor grooves of the two dA-tracts are suggested to be rather narrow, and the portion linking the two dA tracts exhibits a slightly deviated structure from a standard B DNA, in order to maintain the narrowness of the minor groove. The structure of the dG-tract is also slightly deviated. Additionally, specific broadening of resonances is observed for the residues at or near the junction between the dA-tract and the dG-tract, suggesting local structural polymorphology.

[Spinal cord stimulation therapy at an early stage for unresponsive patients with hypoxic encephalopathy]

Recently, spinal cord stimulation (SCS) has been used for the treatment of patients in prolonged coma. However, the results of SCS in unresponsive patients with hypoxic encephalopathy at the chronic stage have not been satisfactory. Considering these circumstances, we began SCS from one month after the onset of hypoxic encephalopathy and evaluated its effect. Twelve patients (5 males and 7 females) with hypoxic encephalopathy, ranging in age from 7 to 72 years, were treated with SCS. The causes of hypoxia were acute cardiac failure in 4, automobile exhaust gas poisoning in 2, and asthma, pneumothorax, anaphylaxis, asphyxia, drowning and hypotension during aortic surgery in one patient each. One month after the onset, an electrode for electrical stimulation was implanted in the epidural space at the C2-C4 level under general anesthesia. The spinal cord was stimulated for 8 hours each day, starting on the day after implantation, and was continued for 3 months. Magnetic resonance imaging (MRI), cerebral blood flow (CBF) measurement using xenon-computed tomography (Xe-CT), and measurement of auditory evoked potential (AEP) and somatosensory evoked potential (SEP) were carried out 3 weeks after the onset for presurgical evaluation. Among the 12 patients, 7 (58%) showed clinical improvement, beginning within two weeks after starting stimulation. They were able to communicate with others and to express their emotion. However, disturbance of writing, picture drawing and calculation were not improved by stimulation. From presurgical evaluation, cases in which SCS therapy was effective had the following features: 1) No hemorrhagic infarction in the basal ganglia was demonstrable by MRI. 2) Mean hemispheric CBF measured by the Xe-CT method exceeded 25 ml/100 g per min. 3) The mean increase in hemispheric CBF 20 min after acetazolamide administration exceeded 5 ml/100 g per min. 4) An N20 peak was evident on the median nerve SEP, SCS appears to be an effective supplementary for unresponsive patients with hypoxic encephalopathy at the subacute stage, in addition to rehabilitation and drug therapy.

Activation and repression of the activity of a lead ribozyme by the combination of Pb2+ and Mg2+

The effect of Pb2+ and Mg2+ on the activity of a lead ribozyme with modified sequences has been studied. At low Pb2+ concentrations, cleavage at a previously reported site (site a) is observed. At higher Pb2+ concentrations, cleavage at a new site (site b) adjacent to site a is observed, while the cleavage at site a is repressed. On the addition of a certain amount of Mg2+, the cleavage at site a is enhanced by almost fourfold, while the cleavage at site b is repressed. Further addition of Mg2+ represses the cleavage at both sites. CD analysis indicates that the structure and stability of the lead ribozyme change depending on the metal conditions. Activation and repression of the activity by the combination of Pb2+ and Mg2+ are rationalized by considering that the two metals compete with each other for binding at two metal-binding sites.

Dimerization and DNA binding facilitate alpha-helix formation of Max in solution

Max is a basic region/helix-loop-helix/leucine zipper (b/HLH/Z) protein that forms a hetero-complex with the Myc family proteins Myc, Mad, and Mxi1, and a homo-complex with itself. These complexes specifically bind to double-stranded DNA containing CACGTG sequences. Here, we report on the structural properties in aqueous solution of a 109-amino-acid protein, Max110, corresponding to the N-terminal domain of Max containing the b/HLH/Z motif (residues 2-110), as characterized by combined use of circular dichroism (CD) and sedimentation equilibrium experiments. The results showed that the alpha-helical content of Max110 increases with increasing protein concentration. The sedimentation equilibrium data indicated that Max110 exists as a monomer at low protein concentration, and forms a dimer at high protein concentration. Further increases in the alpha-helical content of Max110 occur upon addition of DNA with the CACGTG recognition sequence. Thus, dimerization and binding to DNA of Max both favor an increase of the alpha-helical content.

Hairpin structure of an RNA 28-mer, which contains a sequence of the enzyme component of a hammerhead ribozyme system: evidence for tandem G:A pairs that are not of side-by-side type

An RNA 28-mer (Rz28) was obtained as a major product by in vitro transcription with T7 RNA polymerase of a promoter-template DNA, which contains a sequence for the enzyme component, RNA 24-mer (Rz24), of a mutant hammerhead ribozyme system. Sequence analysis and enzymatic probing study showed that Rz28 has 4 extra nucleotides at the 3'-terminus, the sequence of which is complementary to that of the 5'-terminal sequence of Rz24, and forms a stable hairpin structure. NMR studies using a 15N-guanine-labeled derivative suggested that Rz28 contains tandem G:A pairs that are not of the side-by-side type which is found in the crystal structure of hammerhead ribozyme complexes. Comparison of the HMQC spectra of 15N-guanine-labeled Rz28 and Rz24 suggested that Rz24 also contains the same type of tandem G:A pairs.

Properties of hepatitis delta virus ribozyme, which consists of three RNA oligomer strands

Properties of a hepatitis delta virus (HDV) RNA ribozyme system, which consists of three RNA oligomer strands (substrate 8-mer; enzyme 16-mer plus 35-mer) and contains a hybrid sequence of genomic and antigenomic RNA cores, are reported. Effects of Mg2+ concentration, divalent metal ion species, pH, and temperature on the cleavage activity were examined. The substrate cleavage activity increased with increasing Mg2+ concentration (0-100 mM). Ca2+ and Mn2+ ions were the most effective divalent cations and Mg2+ was less effective. The cleavage activity increased with increasing pH (5-7.5). The optimum temperature for the cleavage activity was 25-40 degrees C. The Mg2+ concentration, pH and temperature dependencies are different from those reported for the single-strand ribozymes (about 90-mer) although the divalent metal ion preference is very similar. Conformational change induced by Mg2+ ion titration was monitored by CD. The CD data and the activity-Mg2+ concentration data were analyzed by curve-fitting analysis using equations derived for multiple metal ion binding mechanisms. The data can be explained by a model in which three Mg2+ ions bind to one ribozyme unit.

Essential lysine residues in the N-terminal and the C-terminal domain of human adenylate kinase interact with adenine nucleotides as found by site-directed random mutagenesis

To elucidate the minimum requirement of amino acid residues for the active center in human adenylate kinase (hAK1), we carried out random site-directed mutagenesis of key lysine residues (K9, K21, K27, K31, K63, K131, and K194), which were conserved in mammalian AK1 species, with the pMEX8-hAK1 plasmid [Ayabe, T., et al. (1996) Biochem. Mol. Biol. Int. 38, 373-381]. Twenty different mutants were obtained and analyzed by steady-state kinetics, and all mutants showed activity loss by Km and/or k(cat) effects on MgATP2-, AMP2-, or both. The results have led to the following conclusions. (1) Lys9 would appear to interact with both MgATP2- and AMP2- but to a larger extent than with AMP2-. (2) Lys21 is likely to play a role in substrate binding of both MgATP2- and AMP2- but more strongly affects MgATP2-. (3) Lys27 and Lys131 would appear to play a functional role in catalysis by interacting strongly with MgATP2-. (4) Lys31 would appear to interact with MgATP2- and AMP2- at the MgATP2- site. (5) Lys63 would be more likely to interact with MgATP2- than with AMP2-. (6) Lys194 in the flanking C-terminal domain would appear to interact not only with MgATP2- but also with AMP2- at the MgATP2- site by stabilizing substrate binding. The loss of the positively charged epsilon-amino group of lysine affects both the affinity for the substrate and the catalytic efficiency. Hence, hydrophilic lysine residues in hAK1 would appear to be essential for substrate-enzyme interaction with the coordination of some arginine residues, reported previously [Kim, H. J., et al. (1990) Biochemistry 29, 1107-1111].

Idiopathic cranial pachymeningoencephalitis focally affecting the parietal dura mater and adjacent brain parenchyma: case report

OBJECTIVE AND IMPORTANCE

Cranial pachymeningitis is a typically diffuse granulomatous disease, which often affects the tentorium and falx. We report a rare case of idiopathic cranial pachymeningoencephalitis focally affecting only the left parietal dura mater and adjacent inferior parietal lobule.

CLINICAL PRESENTATION

A 46-year-old woman, with no history of disease, suddenly had a generalized convulsion. A gadolinium-enhanced T1-weighted magnetic resonance image showed homogeneously stained meninges extending to the cortical parenchyma with marked perifocal edema. The thickened dura was visualized as a hypointense area on a T2-weighted magnetic resonance image.

INTERVENTION

The patient underwent successful en bloc excision of the mass involving the dura mater and adjacent brain parenchyma. Histological examination of the dura mater revealed large numbers of chronic and acute inflammatory cells. These cells were also present in the subarachnoid and Virchow-Robin spaces and part of the brain parenchyma in the resected cortex. After the operation, the patient experienced no neurological deficits or recurrent mass for 10 months.

CONCLUSION

Early diagnosis of pachymeningitis using magnetic resonance imaging is important for the treatment of pachymeningoencephalitis, because diffuse involvement of the dura mater and brain parenchyma can make en bloc excision difficult.

[Motor cortex stimulation therapy in patients with thalamic pain]

Seven patients with thalamic pain were treated by electrical stimulation of the motor cortex. Patients ranged from 55 to 71 years of age. There were six men and one woman. Causes of thalamic pain were thalamic infarction in 2 patients and thalamic hemorrhage in five. Six patients had intractable pain associated with dysesthesia in the upper and lower limb (upper limb dominant). One patient had intractable pain in the face contralateral to the lesion. Magnetic resonance images (MRI) were performed in 5 patients and showed the deposit of hemosiderin in the internal capsule, posterolateral nucleus and pulvinar. Electrodes were placed on the motor cortex epidurally in seven patients. Electrodes were implanted permanently in six patients and removed in one patient after an unsatisfactory result of test stimulation. Motor cortex stimulation provided satisfactory pain relief in all six patients for a month after the beginning of stimulation, however, by the time three months had passed, pain relief had become gradually unsatisfactory in five patients. We compared pain relief between 10 Hz and 100 Hz of stimulus rate in four patients and observed that all patients complained of fatigue in the upper extremity at the 100 Hz of stimulus rate, though no differences in pain relief was obtained according to which of these two stimulus rates were used. We concluded that motor cortex stimulation brought about pain inhibition in patients with thalamic pain, but pain control tended to become less gradual within several months after the beginning of stimulation.

Structural properties and RNA-binding activities of two RNA recognition motifs of a mouse neural RNA-binding protein, mouse-Musashi-1

mouse-Musashi-1 (m-Msi-1) is an RNA-binding protein, abundantly expressed in the developing mammalian central nervous system (CNS). m-Msi-1 contains two RNA recognition motifs (RRMs). In this study, we found that the N-terminal RRM of m-Msi-1 (MMA) binds strongly to poly(G) and weakly to poly(U) in a way similar to that of the full-length m-Msi-1 protein characterized previously. The C-terminal RRM of m-Msi-1 (MMB), however, does not bind to RNA. In addition, the circular dichroism (CD) spectra of the two RRMs showed that the alpha-helical content of MMA is significantly higher than that of MMB, indicating that some differences in the secondary structure may be responsible for the distinct RNA binding properties of MMA and MMB.

Substrate-binding and catalytic roles of Lys194 in the C-terminus in human adenylate kinase by site-directed random mutagenesis

Site-directed random mutagenesis of Lys194 residue in the C-terminus of human adenylate kinase (AK) was performed, and six mutants were analyzed by steady-state kinetics. K194-mutants variously affected the apparent Michaelis constants (K(m) values) for ATP and AMP, although the kcat values strikingly decreased. The Lys194 residue appears to interact not only with MgATP2- but also with the AMP2- substrates by salt bridge formation with a nucleotide and to play a functional role in stabilizing the phosphate-transfer during catalysis. Lys194 could be essential for substrate-holdings and in catalysis and not replaceable to the other amino acids.

Effects of 2'-substituents of the first deoxyguanosine residue in the recognition sequence of EcoRI restriction endonuclease activity

The effects of 2'-substituents of the first deoxyguanosine on EcoRI activity were examined using synthetic octadeoxynucleotides D(GG*AATTCC) containing 2'-substituted derivatives (G*), i.e., 2'-fluoro-2'-deoxyguanosine (dGfl), 2'-chloro-2'-deoxyguanosine (dGcl), and guanosine (rG). The overall structures of the octamers were very similar, as shown by CD and UV measurements, although their EcoRI reactivities were very different: 100% in 60 min for d(GGAATTCC) and d(GGflAATTCC), 5% in 24 h for d[G(rG)AATTCC], and no cleavage at all in 24 h for d(GGclAATTCC). However, the kinetics showed the octamers exhibit similar binding-affinity to the enzyme (10(-6)-10(-7) M). 31P-NMR analysis suggested the modified octamers change the phosphate backbone conformation in a duplex, since an unusual downfield-shifted signal in the spectra was commonly observed for the modified octamers at low temperature (i.e., a duplex state), which was shifted upfield at high temperature (i.e., a single strand state). The order of the differences was dGcl > rG > dGfl-containing octamers, coinciding with that of the vdW volume of 2'-substituents (Cl > OH > F) and the cleavage reactivities. These findings suggest that steric hindrance by the 2'-substituents causes of conformational change of the phosphate backbone close to the scissile bond, and then interferes with the EcoRI reaction.

Properties of a hammerhead ribozyme with deletion of stem II

The properties of a mutant hammerhead ribozyme system, which consists of two RNA oligomer strands and in which stem II is deleted (replaced with a UUUU loop), are described. The effects of temperature, pH, and metal ions on the cleavage reaction were similar to those for the parent ribozyme with stem II. The mutant ribozyme showed a much lower cleavage rate (kcat = 0.04 min-1) in the presence of 10 mM MgCl2, where the parent ribozyme showed full cleavage activity. However, increasing the concentration of MgCl2 from 10 to 100 mM restored the cleavage activity of the mutant ribozyme to the original level (kcat = 0.2 min-1). CD titration experiments with MgCl2 using a noncleavable substrate were carried out. Deletion of stem II resulted in an about 20-fold reduction of the apparent Mg2+ binding affinity when the Mg2+ concentrations of half-saturation are compared. The results were analyzed by curve-fitting analysis and compared with those for the parent ribozyme. The analysis showed that the Mg2+ concentration dependence data in CD and cleavage experiments for the mutant enzyme can be explained by a two Mg2+ ion binding mechanism. These results that stem II is important for maintaining the conformation of the catalytic core suitable for Mg2+ binding.

Catalytic roles of lysines (K9, K27, K31) in the N-terminal domain in human adenylate kinase by random site-directed mutagenesis

To elucidate lysine residues in the N-terminal domain of human cytosolic adenylate kinase (hAK1, EC 2.7.4.3), random site-directed mutagenesis of K9, K27, and K31 residues was performed, and six mutants were analyzed by steady-state kinetics. K9 residue may play an important role in catalysis by interacting with AMP2-. K27 and K31 residues appear to play a functional role in catalysis by interacting with MgATP2-. In human AK, the epsilon-amino group in the side chain of these lysine residues would be essential for phosphoryl transfer between MgATP2- and AMP2- during transition state.

Analysis of the mRNA cap-binding ability of human eukaryotic initiation factor-4E by use of recombinant wild-type and mutant forms

In order to identify the amino acid residues necessary for the selective recognition of the mRNA cap structure by human eukaryotic initiation factor-4E (eIF-4E), which plays a central role in the first step of mRNA translation, we prepared recombinant wild-type and fourteen mutant forms and compared their cap-binding abilities by affinity chromatography. By the direct expression of a synthetic gene encoding human eIF-4E as the soluble form in Escherichia coli and the application on a 7-methylguanosine-5'-triphosphate-Sepharose 4B cap affinity column, pure recombinant eIF-4E was prepared; the optimum pH for the binding of the mRNA cap was 7.5. Among the amino acid residues conserved among various eIF-4E species, each of 14 functional residues was replaced with a nonpolar amino acid (alanine or leucine). All mutant eIF-4E genes, which were constructed by site-directed mutagenesis, were expressed in the same way as the wild type, and their cap-binding abilities were compared with that of the wild type. Consequently, all eight tryptophan residues. Glu103, and two histidine residues at positions 37 and 200 in human recombinant eIF-4E were suggested to be important for the recognition of the mRNA cap structure through direct interaction and/or indirect contributions. Indirect contributions included the construction of the overall protein structure, especially the cap-binding pocket.

Mouse-Musashi-1, a neural RNA-binding protein highly enriched in the mammalian CNS stem cell

There is increasing interest in the role of RNA-binding proteins during neural development. Drosophila Musashi is one of the neural RNA-binding proteins essential for neural development and required for asymmetric cell divisions in the Drosophila adult sensory organ development. Here, a novel mammalian neural RNA-binding protein, mouse-Musashi-1, was identified based on the homology to Drosophila Musashi and Xenopus NRP-1. In the developing CNS, mouse-Musashi-1 protein was highly enriched in the CNS stem cell. Single-cell culture experiments indicated that mouse-Musashi-1 expression is associated with neural precursor cells that are capable of generating neurons and glia. In contrast, in fully differentiated neuronal and glial cells mouse-Musashi-1 expression is lost. This expression pattern of mouse-Musashi-1 is complementary to that of another mammalian neural RNA-binding protein, Hu (a mammalian homologue of a Drosophila neuronal RNA-binding protein Elav), that is expressed in postmitotic neurons within the CNS. In vitro studies indicated that mouse-Musashi-1 possesses binding preferences on poly(G) RNA homopolymer, whereas Hu is known to preferentially bind to short A/U-rich regions in RNA. Based on their differential expression patterns and distinct preferential target RNA sequences, we believe that the mouse-Musashi-1 and Hu proteins may play distinct roles in neurogenesis, either through sequential regulatory mechanisms or differential sorting of mRNA populations during asymmetric division of neural precursor cells.

[Methicillin-resistant Staphylococcus aureus infection in the Akita University Hospital: surveillance and microbiology data]

In order to control the nosocomial infections by methicillin-resistant Staphylococcus aureus (MRSA) in the Akita University Hospital, the systematic surveillance for MRSA-infection has been done since October in 1991. We reviewed MRSA-isolation numbers, MRSA-detected patient numbers, risk factors of nosocomial infection and patient's basic diseases with the data of a total 336 cases, and then examined the microbiological characteristics of MRSA strains which had been isolated in our hospital in 1986 approximately 1994. The results obtained are as follows; 1) MRSAs were isolated at 13 per month on the average and the detection rate was 0.81 to 1,000 inpatients per day. 2) MRSAs were isolated more in the surgical ward. 3) Patients with 0 year old and more than 60 years old were more infected. 4) MRSA was isolated more from the immunocompromised patients with underlying diseases such as malignant tumors but half of the diseases were not affected by MRSA. 5) Seventy percent of patients had the risk factors of MRSA-transmission such as surgical operation and IVH-cathetering. 6) All isolates of MRSA strains in our hospital showed type II in coagulase type analysis and resistance to minocycline and ofloxacin. 7) It was suggested that one strain expanded throughout the hospital by several DNA analysis with the mecA gene in MRSA. These surveillance and microbiology data will be useful for our nosocomial mecA gene in MRSA. These surveillance and microbiology data will be useful for our nosocomial infection control.

Steady-state kinetics of Thr35 and Thr39 mutants in human adenylate kinase by site-directed mutagenesis

Adenylate kinase (AK; EC 2.7.4.3, hAK1) catalyzes the reaction: MgATP(2-)+ AMP2- reversible MgADP-(+) ADP3-. To elucidate the catalytic and structural roles of threonine residues in human AK, Thr35 and Thr39 mutants were analyzed by steady-state kinetics. The K(m) values of T35P and T35Y were not changed for MgATP2- and AMP2-, and the kcat values were decreased by 1/39 compared to those of wild-type AK. Thr35 was suggested to be essential for catalysis. The K(m) values of T39S, T39V and T39P were increased 5.6- to 59.0-fold for AMP2-; however, the kcat values were not reduced. Although the K(m) values of T39F and T39L were unchanged, the kcat values were reduced by more than 1/57. Thr39 appears to play an important role in the binding of AMP2- and to be essential for catalysis. As noted above, a hydroxyl group of the Thr residue in human AK appears to be important.

Activity of artificial mutant variants of human growth hormone changes in charged residues around 62-67

Our previous work has shown that the amino acid residues around 62-67 located in the connecting loop between helix I and II of human growth hormone (hGH) are important in eliciting the differentiation of preadipose 3T3-F442A cells to adipocytes. In this study, we evaluated the role of the charged residues around 62-67 in receptor binding and biological activity. Eight artificial mutant variants of hGH were prepared in Escherichia coli by site-directed mutagenesis. Replacement of Arg64 with Tyr (R64Y variant) resulted in a significant loss of binding to the somatogenic receptors on 3T3-F442A cells, but retained full adipose conversion activity on these cells. Replacement of Arg64 with Glu (R64E) produced a considerable loss in receptor binding and a significant loss in biological activity. hGH variants in which either Glu65 or Glu66 was replaced with Asp (E65D and E66D) and with Gln (E65Q and E66Q) showed a slight loss in binding activity and retained almost a full adipogenic activity. An E65P variant (replacement of Glu65 with Pro) possessed the same binding activity as hGH, although it failed to induce full biological activity. The insertion of Ala between Asn63 and Arg64 (63NAR) caused a marked loss in both activities. These results indicate that the positively charged Arg64 is important for receptor binding and thereby in eliciting the biological activity of hGH, while negatively charged Glu65 and Glu66 are less important. In addition, our findings confirm that the conformation and size of the loop region around Arg64 is important for the adipose conversion activity of hGH.

[Restriction fragment length polymorphism of coagulase gene of methicillin-resistant Staphylococcus aureus can be used as an epidemiological marker]

In order to see the restriction fragment length polymorphism (RFLP) of coagulase gene of Methicillin-resistant Staphylococcus aureus (MRSA) and the type of coagulase, a total of 118 strains of MRSA from 1986 to 1994 was collected from the Akita University Hospital, six hospitals in Akita Prefecture and a hospital in Aomori Prefecture. The RFLP analysis using the Alu I restriction enzyme brought us four kinds of electrophoretic patterns (A, B, C, D). Patterns A (87%) and B (13%) were detected in our hospital and only pattern A was detected in other hospitals in Akita. On the other hand, Patterns A (68%), B (26%), C (3%) and D (3%) were detected in Aomori. In coagulase type analysis, all strains in Akita showed type II, and the strains in Aomori also showed type II except for one strain (type IV). From the above results, the polymorphism of coagulase gene of MRSA can be useful as an epidemiological marker to examine the extent of MRSA infection in a prefecture unit or in a larger area.

[The role of hypertension as a risk factor of atherosclerosis]

Epidemiologic studies have demonstrated hypertension is one of the risk factors of atherosclerosis, but the underlying mechanism is complex and still controversial. Salt-sensitivity is an important characteristic demonstrated in a subgroup of hypertension, since the factors relating to salt-sensitivity also influence smooth muscle hypertrophy and proliferation which are essential processes of atherosclerosis. Insulin resistance is also involved in the causal relationship between hypertension and atherosclerosis, because accumulating data indicate a central role of insulin resistance in patients with hypertension, glucose-intolerance and dyslipidemia. Vasoacting substances give direct effects on not only the tension but also the growth of smooth muscle cells, namely vasodilators, such as nitric oxide and atrial natriuretic peptides inhibit the proliferation of smooth muscle cells. On the other hand, vasoconstrictors such as angiotensin II, vasopressin and endothelin promote the proliferation of smooth muscle cells. The factors which influence both tension and proliferation of smooth muscle cells may play a central role in the relationship between hypertension and atherosclerosis.

Soluble expression of a synthetic gene for human translation initiation factor 4E in Escherichia coli

In order to obtain the active form of recombinant human initiation factor (eIF) 4E effectively, an artificial synthetic gene was cloned into an expression vector (pMAL-p2) and the soluble expression was attempted in Escherichia coli under the control of a tac promoter. Two expression systems were finally constructed as a fusion protein with maltose-binding protein, which contain a recognition sequence for the site specific protease alpha-thrombin and factor Xa, respectively. Most of the fusion protein was induced as a soluble form. The soluble human eIF-4E digested from the fusion protein showed binding specificity for the m7GTP affinity column.