A reactive hydroxymethyl sulfate ester formed regioselectively from the carcinogen, 7,12-dihydroxymethylbenz[alpha]anthracene, by rat liver sulfotransferase

The carcinogen, 7,12-dihydroxymethylbenz[alpha]anthracene (DHBA), was regioselectively conjugated in the presence of 3'-phosphoadenosine 5'-phosphosulfate by male rat liver cytosolic sulfotransferase to DHBA 7-sulfate. The sulfate ester was highly reactive and showed a potent, intrinsic mutagenicity toward Salmonella typhimurium TA 98.     

Insulin and C-peptide secretion from B cells in human subjects stimulated with glucose

Two groups of immunoreactive insulin in human sera were reported by Kakita et al. (4), using gel chromatography after acid-alcohol extraction. These analogs were noted not only in circulating human sera but also in incubation medium and incubated human pancreas. The release of these insulin analogs was discussed in a previous report (5). The circulating C-peptide immunoreactivity was separated into two groups on a Bio-Gel column, and the early peak should not be proinsulin but an associated C peptide (6). These analogs of insulin were separated by the methods of ion-exchange chromatography, isoelectric focusing, gel electrophoresis, and gel chromatography. Immunoreactive insulin was also separated into two major bands by standard polyacrylamide gel electrophoresis. The fast migrating band corresponds to the rat insulin II position, and the slower corresponds to rat insulin I, which has one more basic amino acid residue in comparison with rat insulin II. Further studies have been performed in five healthy adults in order to elucidate the physiological relationship between analogs of insulin and C-peptide peak substances in human serum; the results are reported in this paper with a consideration of the mechanism of insulin secretion.     

Differentiation by cholinergic stimulation of positive inotropic actions mediated via alpha- and beta-adrenoceptors in the rabbit heart.

In the isolated rabbit papillary muscle, experiments were carried out in order to elucidate whether or not cholinergic stimulation produces a differential antagonistic action on the positive inotropic effects mediated $\text{via}$ β- and α-adrenoceptor stimulation. Carbachol (0.1–30 μM) alone scarcely affected the basal tension developed. The postive inotropic effects of phenylephrine (30 μM) in the presence of phentolamine and of isoprenaline, which were mediated $\text{via}$ β-adrenoceptors, were markedly inhibited by carbachol. Carbachol (3 μM) shifted the dose-response curve for isoprenaline in a parallel manner, and that for phenylephrine with phentolamine to the right and downwards. Carbachol administered during induction of the positive inotropic effects $\text{via}$ α-adrenoceptors by phenylephrine (30 μM) with pindolol or by methoxamine failed to inhibit these effects and increased further the tension developed. The dose-response curve for phenylephrine determined in the presence of pindolol was not affected by carbachol. The present results indicate that the cholinergic antagonism of the adrenergic action on the contractility of the mammalian ventricular myocardium is exerted specifically to the β-adrenoceptor-mediated action, but not to the α-adrenoceptor-mediated one.     

Improved nearest-neighbor parameters for the stability of RNA/DNA hybrids under a physiological condition

The stability of Watson–Crick paired RNA/DNA hybrids is important for designing optimal oligonucleotides for ASO (Antisense Oligonucleotide) and CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)–Cas9 techniques. Previous nearest-neighbour (NN) parameters for predicting hybrid stability in a 1 M NaCl solution, however, may not be applicable for predicting stability at salt concentrations closer to physiological condition (e.g. ∼100 mM Na⁺ or K⁺ in the presence or absence of Mg²⁺). Herein, we report measured thermodynamic parameters of 38 RNA/DNA hybrids at 100 mM NaCl and derive new NN parameters to predict duplex stability. Predicted ΔG°₃₇ and T_m values based on the established NN parameters agreed well with the measured values with 2.9% and 1.1°C deviations, respectively. The new results can also be used to make precise predictions for duplexes formed in 100 mM KCl or 100 mM NaCl in the presence of 1 mM Mg²⁺, which can mimic an intracellular and extracellular salt condition, respectively. Comparisons of the predicted thermodynamic parameters with published data using ASO and CRISPR–Cas9 may allow designing shorter oligonucleotides for these techniques that will diminish the probability of non-specific binding and also improve the efficiency of target gene regulation.     

A protein-protein interaction in magnetosomes: TPR protein MamA interacts with an Mms6 protein

Magnetosomes are membrane-enveloped bacterial organelles containing nano-sized magnetic particles, and function as a cellular magnetic sensor, which assist the cells to navigate and swim along the geomagnetic field. Localized with each magnetosome is a suite of proteins involved in the synthesis, maintenance and functionalization of the organelle, however the detailed molecular organization of the proteins in magnetosomes is unresolved. MamA is one of the most abundant magnetosome-associated proteins and is anchored to the magnetosome vesicles through protein-protein interactions, but the identity of the protein that interacts with MamA is undetermined. In this study, we found that MamA binds to a magnetosome membrane protein Mms6. Two different molecular masses of Mms6, 14.5-kDa and 6.0-kDa, were associated with the magnetosomes. Using affinity chromatography, we identified that the 14.5-kDa Mms6 interacts with MamA, and the interaction was further confirmed by pull-down, immunoprecipitation and size-exclusion chromatography assays. Prior to this, Mms6 was assumed to be strictly involved with biomineralizing magnetite; however, these results suggest that Mms6 has an additional responsibility, binding to MamA.     

Constructing a local district telepathology network in Japan. Diagnosis of intraoperative frozen sections via telepathology over an integrated service digital network and the National Television Standard Committee System

OBJECTIVE: To construct a local telepathology network between the Department of Pathology, Tohoku University Hospital, and Koritu Kesennuma Hospital, about 150 km away. STUDY DESIGN: Tohoku University Hospital is connected with Koritu Kesennuma Hospital by an integrated service digital network for telepathology using the National Television Standard Committee system. The cases submitted for telepathology were limited to those in which a rapid intraoperative diagnosis was made on frozen sections. RESULTS: At this writing, more than 200 cases were diagnosed during a period of 2.5 years. The cases submitted increased with time, amounting to 150 in 1996. In some cases the use of telepathology proved to be fairly advantageous. For example, in one case a radical operation was avoided because of a diagnosis on intraoperative frozen sections. DISCUSSION: There are problems to be solved before telepathology becomes available for practical use: (1) misdiagnosis due to poor quality of instruments, including the transmission cable and pictures; (2) cost-benefit ratio, (3) protection of patients' privacy, and (4) overwork for pathologists. The Japanese government will officially accept telepathology as a means of medical examination in the future. Despite some problems left, telepathology is a promising technology.     

Unusual distribution of mitochondrial large subunit rRNA in the cytosol during conjugation in Tetrahymena thermophila

The distribution of mitochondria during conjugation of the ciliated protozoan Tetrahymena thermophila was surveyed using a mitochondrial stain and fluorescence in situ hybridization (FISH). When the mitochondria-specific stain, Mito-Tracker, was used, the majority of mitochondria were detected in the cortex; their distribution was not changed during conjugation. On the other hand, FISH using mitochondrial large subunit (LSU) rRNA as a probe showed an unusual distribution of signals during conjugation. Unexpectedly, the signals were detected throughout the cytoplasm of conjugating cells. These signals were not observed in pre-mating cells and in exconjugants. The cytosolic localization of mitochondrial rRNA was supported by northern blot analysis using post-mitochondrial RNA fraction at the later stages of conjugation. These observations suggest selective mitochondrial breakdown or transport of LSU rRNA into cytosol. The biological significance of the conjugation-specific appearance of the cytosolic mitochondrial rRNA is discussed.