Archaeosine is a novel derivative of 7-deazaguanosine found in transfer RNAs of most organisms exclusively in the archaeal phylogenetic lineage and is present in the D-loop at position 15. We show that this modification is formed by a posttranscriptional base replacement reaction, catalyzed by a new tRNA-guanine transglycosylase (TGT), which has been isolated from Haloferax volcanii and purified nearly to homogeneity. The molecular weight of the enzyme was estimated to be 78 kDa by SDS-gel electrophoresis. The enzyme can insert free 7-cyano-7-deazaguanine (preQ0 base) in vitro at position 15 of an H. volcanii tRNA T7 transcript, replacing the guanine originally located at that position without breakage of the phosphodiester backbone. Since archaeosine base and 7-aminomethyl-7-deazaguanine (preQ1 base) were not incorporated into tRNA by this enzyme, preQ0 base appears to be the actual substrate for the TGT of H. volcanii, a conclusion supported by characterization of preQ0 base in an acid-soluble extract of H. volcanii cells. Thus, this novel TGT in H. volcanii is a key enzyme for the biosynthetic pathway leading to archaeosine in archaeal tRNAs.
7 pediatric patients with injuries of basal ganglia following head trauma were reported. They ranged in age from 10 months to 10 years. 5 boys and 2 girls comprised the patients. Cases 1–4 are mild cases in which the children fell down backward while playing, followed by a minimum loss of consciousness. In every case there was hemiparesis, but all of them showed remarkable recovery. CT findings are that of unilateral basal ganglia infarction. In cases 5–7, patients suffered from symptoms of brain contusion after running out in front of an oncoming car, and they developed hemiparesis. CT findings in cases 5 and 6 showed unilateral infarction. CT of case 7 showed a massive unilateral hemorrhage of the basal ganglia. All 7 cases sustained only slight scalp wounds and no skull fracture in spite of the severity of injuries signs and CT findings. This discrepancy seems to be explained only by the so-called shearing strain theory. But we have hypothesized that anterior stretch of the lateral branch of the perforator of the middle cerebral artery plays a major role in its pathogenesis.
The electronic structure and optical rotatory power of 2,2'-dihydroxy-l,l'-binaphthyl were examined from the theoretical and experimental points of view. The theoretical calculation was performed by calculating the electric and magnetic dipole velocities directly on the basis of the electronic wave functions obtained by the Pariser-Parr-Pople and composite-molecule treatments. The observed CD spectrum is shown to be well interpreted on the basis of the theoretical results. The contributions of several types of interactions (such as charge transfer, electrostatic, and exciton type) between the -electron systems of two aromatic rings to the optical rotatory power are examined in detail. The result shows that the exciton-type interaction is most important to determine the rotational strength, in accordance with the conventional coupled-oscillator model. However, the present analysis shows clearly that the first-order exciton interaction with nearby excited states is important, as well as the zerothorder exciton interaction. In particular, the former interaction is shown to account predominantly for the circular dichroism spectra accompanying the relatively weak transitions in the longer wavelength region. This point has not been recognized fully in the theoretical calculation of optical activity. Discussion on the determination of the dihedral angle and absolute configuration is given briefly in view of the present theoretical results, together with the discussion on the electronic structure and optical rotatory power of some related binaphthyl derivatives.
A convenient new method for synthesizing queuine (1 ) (2-amino-5-[ (1 S,2R,3S)-2,3-dihydroxycyclopent-4-enylaminomethyl]pyrrolo [2,3-d]pyrimidin-4(3H)-one}, the base of the naturally occurring hypermodified nucleoside, queuosine, present in certain transfer RNAs, and its biosynthetic precursor, 2-amino-5-aminomethyIpyrrolo[2,3-~ pyrimidin-4(3H) -one (2) (Pre Q1 base), was successfully exploited. This method involved two critical reactions: the Mannich reaction using dibenzylamine-formaldehyde of 2-acylaminopyrrolo[2,3-d]pyrimidin-4(3H)-one (7), which resulted in the selective introduction of the dibenzylaminomethyl group into the 5-position of (7), and an amine exchange reaction of the 5-dibenzylamino function in the resulting Mannich base (1 7) with (1 S,2Rr3S) -2,3-isopropylidenedioxycyclopent-4-enylamine, which yielded the desired queuine (1). Similar reaction of (17) with ammonia gave the biosynthetic precursor of queuine (2) (Pre Q1 base). Thus, a series of queuine analogues with structural variations in their 5-aminomethyl side-chains was synthesized b y the amine exchange reaction of (17) with appropriate amines or b y acylation of (2) with appropriate acylating agents.is the base of a hypermodified nucleoside, queuosine, located in the first position of the anticodon of tRNA molecules from various organisms, including mammalian tissues. Because of its unique structure and particular biosynthesis, much attention has been focussed on its biological function in cells, tissues, and whole mammals. ' Its functional role, however, remains to be clarified.The present study was initiated in order to obtain a sample, sufficient in amount to allow further extensive biological studies of (1) ' The first total syntheses of queuosine, queuine, and its biosynthetic precursor,2 pre Q 1 base (2) (2-amino-5-aminomethylpyrrolo[2,3-d]-pyrimidin-4(3H)-one), were achieved by Goto et ~1 . ~ However, their methods of synthesis, although elegant, require extremely lengthy and multistep procedures which are inefficient when synthesizing large quantities of (1) and its analogues for extensive biological studies.
BackgroundThe level of intestinal fatty acid-binding protein (I-FABP) is considered to be useful diagnostic markers of small bowel ischemia. The purpose of this retrospective study was to investigate whether the serum I-FABP level is a predictive marker of strangulation in patients with small bowel obstruction (SBO).MethodsA total of 37 patients diagnosed with SBO were included in this study. The serum I-FABP levels were retrospectively compared between the patients with strangulation and those with simple obstruction, and cut-off values for the diagnosis of strangulation were calculated using a receiver operating characteristic curve. In addition, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated.ResultsTwenty-one patients were diagnosed with strangulated SBO. The serum I-FABP levels were significantly higher in the patients with strangulation compared with those observed in the patients with simple obstruction (18.5 vs. 1.6 ng/ml p<0.001). Using a cut-off value of 6.5 ng/ml, the sensitivity, specificity, PPV and NPV were 71.4%, 93.8%, 93.8% and 71.4%, respectively. An I-FABP level greater than 6.5 ng/ml was found to be the only independent significant factor for a higher likelihood of strangulated SBO (P = 0.02; odds ratio: 19.826; 95% confidence interval: 2.1560 – 488.300).ConclusionsThe I-FABP level is a useful marker for discriminating between strangulated SBO and simple SBO in patients with SBO.
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