What are the post-ablation insular residual electrograms in the posterior left pulmonary veins electrically connected to?

A 67-year-old man underwent a third ablation procedure for a recurrent atrial tachycardia (AT) after an extensive pulmonary vein (PV) isolation, linear ablation along the left atrial (LA) roof and posterolateral mitral isthmus (MI), and defragmentation of persistent atrial fibrillation and an induced perimitral AT. High-resolution mapping during the clinical AT using the Rhythmia system (Boston Scientific) suggested that the AT was a ridge-related reentrant AT and exhibited a reconnection of the left PVs (LPVs). The residual electrograms in the posterior LPVs were surrounded by endocardial scar, which was like an island consisting of residual LPV electrograms. Retrograde venography of the vein of Marshall (VOM) demonstrated that the VOM reached the posterior left superior PV through the ridge between the LA appendage and left inferior PV and then the LPV carina. An ethanol infusion into the VOM resulted in a simultaneous AT termination and complete electrical isolation of the LPVs, that is, the disappearance of the residual LPV electrograms. The insular residual LPV electrograms in the present case did not appear to be endocardially connected to the LA, because the LPV electrograms were surrounded by endocardial scar and there was a large time gap between the earliest activation in the posterior LPVs and activation in the surrounding area. The VOM course on the venography and elimination of the residual LPV electrograms with an ethanol infusion into the VOM suggested that the insular residual LPV electrograms were electrically connected to the posterolateral LA via the VOM and its branches.     

Cytoplasmic and Mitochondrial Creatine Kinases from the Skeletal Muscle of Sperm Whale (Physeter macrocephalus). Molecular Cloning and Enzyme Characterization

We have amplified two cDNAs, coding for creatine kinases (CKs), from the skeletal muscle of sperm whale Physeter macrocephalus by PCR, and cloned these cDNAs into pMAL plasmid. These are the first CK cDNA and deduced amino acid sequences from cetaceans to be reported. One of the two amino acid sequences is a cytoplasmic, muscle-type isoform (MCK), while the other was identified as a sarcomeric, mitochondrial isoform (sMiCK) that included a mitochondrial targeting peptide. The amino acid sequences of sperm whale MCK and sMiCK showed 94–96% sequence identity with corresponding isoforms of mammalian CKs, and all of the key residues necessary for CK function were conserved. The phylogenetic analyses of vertebrate CKs with three independent methods (neighbor-joining, maximum-likelihood and Bayes) supported the clustering of sperm whale MCK with Bos and Sus MCKs, in agreement with the contemporary view that these groups are closely related. Sperm whale MCK and sMiCK were expressed in Escherichia coli as a fusion protein with maltose-binding protein, and the kinetic constants (K _m, K _d and k _cat) were determined for the forward reaction. Comparison of kinetic constants with those of human and mouse CKs indicated that sperm whale MCK has a comparable affinity for creatine (K _m^Cr = 9.38 mM) to that of human MCK, and the sMiCK has two times higher affinity for creatine than the human enzyme. Both the MCK and sMiCK of sperm whale display a synergistic substrate binding (K _d /K _m = 3.1–7.8) like those of other mammalian CKs.     

Abrupt change in primary productivity in a littoral zone of Lake Biwa with the development of a filamentous green-algal community

1. Some characteristics of the photosynthesis and primary production of benthic and planktonic algal communities were investigated in a littoral zone covered with gravel in the north basin of Lake Biwa, paying special attention to the recent development of filamentous green algae (FGA) in the benthic algal community.
2. P_max (maximum gross photosynthesis rate) values of the benthic algal community (0.1–1.2 mg C mg chl. a ⁻¹ h⁻¹) obtained from photosynthesis–irradiance (P–I) curves were lower than those of the planktonic algal community (2.4–11.5 mg C mg chl. a ⁻¹ h⁻¹). This is apparently a result of the high degree of self shading in the benthic algal community and its low turnover as compared with that of the planktonic algal community.
3. Relatively high I_k values (150–200 μmol photon m⁻² s⁻¹) were observed in the benthic algal community only in June–July when a FGA, Spirogyra sp., was abundant. This reflected a photosynthetic characteristic of the Spirogyra itself, in which photosynthesis was saturated at high light intensity.
4. The FGA community established in the layer between planktonic and sessile (benthic algae except for FGA) algal communities. It brought about extraordinarily high organic matter production in the littoral zone at the expense of production in the sessile algal community.     

Arabidopsis vacuolar sorting mutants (green fluorescent seed) can be identified efficiently by secretion of vacuole-targeted green fluorescent protein in their seeds

Two Arabidopsis thaliana genes have been shown to function in vacuolar sorting of seed storage proteins: a vacuolar sorting receptor, VSR1/ATELP1, and a retromer component, MAIGO1 (MAG1)/VPS29. Here, we show an efficient and simple method for isolating vacuolar sorting mutants of Arabidopsis. The method was based on two findings in this study. First, VSR1 functioned as a sorting receptor for beta-conglycinin by recognizing the vacuolar targeting signal. Second, when green fluorescent protein (GFP) fusion with the signal (GFP-CT24) was expressed in vsr1, mag1/vps29, and wild-type seeds, both vsr1and mag1/vps29 gave strongly fluorescent seeds but the wild type did not, suggesting that a defect in vacuolar sorting provided fluorescent seeds by the secretion of GFP-CT24 out of the cells. We mutagenized transformant seeds expressing GFP-CT24. From approximately 3,000,000 lines of M2 seeds, we obtained >100 fluorescent seeds and designated them green fluorescent seed (gfs) mutants. We report 10 gfs mutants, all of which caused missorting of storage proteins. We mapped gfs1 to VSR1, gfs2 to KAM2/GRV2, gfs10 to the At4g35870 gene encoding a novel membrane protein, and the others to different loci. This method should provide valuable insights into the complex molecular mechanisms underlying vacuolar sorting of storage proteins.     

Zierane sesquiterpene lactone,cembrane and fusicoccane diterpenoids,from the Tahitian liverwort Chandonanthus hirtellus

Cembrane-type diterpenoids, 13,18,20-epi-iso-chandonanthone (1) and (8E)-4α-acetoxy-12α,13α-epoxycembra-1(15),8-diene (2), two fusicoccane-type diterpenoids, fusicoauritone 6α-methyl ether (3) and 6β,10β-epoxy-5β-hydroxyfusicocc-2-ene (4) and a zierane sesquiterpene γ-lactone, chandolide (5) were isolated from the Tahitian liverwort Chandonanthus hirtellus (Web.) Mitt., together with eight known diterpenoids, chandonanthine (6), fusicogigantone A (7), fusicogigantone B (8), fusicogigantepoxide (9), anadensin (10), fusicoauritone (11), ent-verticillol (12) and ent-epi-verticillol (13). Their structures were established by a combination of extensive NMR spectroscopy and/or X-ray crystallographic analyses. Compounds 1, 5 and 10 showed weak cytotoxic activity against HL-60. Compound 3 also indicated weak cytotoxic activity against KB cell lines.     

Short-limbed dwarfism: slw is a new allele of Npr2 causing chondrodysplasia

Short-limbed dwarfism (SLW) is a new mutant mouse characterized by a dwarf phenotype with markedly short body, limbs, and tail. In the present study, we investigated the skeletal phenotypes of the SLW mouse and determined the chromosomal localization to identify the gene responsible for the phenotypes (slw). Skeletal preparations stained with alcian blue and alizarin red revealed that longitudinal growth of the extremities of the affected (slw/slw) mice was significantly reduced in comparison with that of normal mice, whereas the positions and numbers of skeletal elements were normal. Histological examination of tibial growth plates of the affected mice showed that the numbers of proliferating and hypertrophic chondrocytes were obviously diminished. These phenotypes resembled to those of human chondrodysplasias caused by defective chondrocyte proliferation and differentiation. We mapped the slw locus on an 11.7-cM interval of the proximal region of mouse chromosome 4 by linkage analysis. Furthermore, allelism test using Npr2(cn) locus, a mutant allele of Npr2 gene encoding a natriuretic peptide receptor B, revealed that slw locus is an allele of the Npr2 gene. These results suggest that the dwarf phenotype of the SLW mouse is caused by the disturbed endochondral ossification, and a mutation in the Npr2 gene is expected to be responsible for the phenotypes of the SLW mouse.     

Effect of pre-treatment with St John's Wort on nephrotoxicity of cisplatin in rats

An herbal health care supplement, St John's Wort (SJW, Hypericum perforatum) has become widely used in the treatment of depression, and is known to interact with therapeutic drugs. Here we report a preventive effect of SJW on cisplatin nephrotoxicity in rats. Rats were given SJW (400 mg/kg/day, p.o.) for 10 consecutive days, and were injected with cisplatin (5 mg/kg, i.v.) on the day after the final SJW treatment. Cisplatin treatment increased the serum creatinine level, which is an index of nephrotoxicity, to 1.51+/-0.22 mg/dl (mean+/-SE) from 0.28+/-0.05 mg/dl (control) on day 5 after the cisplatin injection. This increase fell significantly to 0.86+/-0.13 mg/dl by pre-treatment with SJW. Cisplatin-induced histological abnormality of the kidney was blocked by pre-treatment with SJW. When SJW was administered for 10 days, the amounts of renal metallothionein (MT) and hepatic multidrug resistance protein 2 (Mrp2) were increased to 164.8+/-13.0% and 220.8+/-39.3% (mean+/-SE) of controls, respectively. GSH levels in the kidney and liver were not changed. Total and free cisplatin concentration in serum was not influenced by SJW treatment. In conclusion, the results suggest that pre-treatment with SJW may diminish cisplatin nephrotoxicity.