l-Carnitine is essential to β-oxidation of quarried fatty acid from mitochondrial membrane by PLA2

Mitochondrial β-oxidation is an important system involved in the energy production of various cells. In this system, the function of l-carnitine is essential for the uptake of fatty acids to mitochondria. However, it is unclear whether or not endogenous respiration, ADP-induced O₂ consumption without substrates, is caused by l-carnitine treatment. In this study, we investigated whether l-carnitine is essential to the β-oxidation of quarried fatty acids from the mitochondrial membrane by phospholipase A₂ (PLA₂) using isolated mitochondria from the liver of rats. Intact mitochondria were incubated in a medium containing Pi, CoA and l-carnitine. The effect of l-carnitine treatment on ADP-induced mitochondrial respiration was observed without exogenous respiratory substrate. Increase in mitochondrial respiration was induced by treatment with l-carnitine in a concentration-dependent manner. Treatment with rotenone, a complex I blocker, completely inhibited ADP-induced oxygen consumption even in the presence of l-carnitine. Moreover, the l-carnitine dependent ADP-induced mitochondrial oxygen consumption did not increase when PLA₂ inhibitors were treated before ADP treatment. The l-carnitine-dependent ADP-induced oxygen consumption did contribute to ATP productions but not heat generation via an uncoupling system. These results suggest that l-carnitine might be essential to the β-oxidation of quarried fatty acids from the mitochondrial membrane by PLA₂.     

Cell wall extensibility during branch formation in the xanthophycean alga Vaucheria terrestris

In the tip-growing filamentous cell of the xanthophycean alga Vaucheria terrestris sensu Götz, a new growing tip develops in the non-growing, cylindrical region of the cell that was exposed by local illumination. The present study examined changes in the strength and extensibility of the cell wall of the new growing tip and in the matrix components of the inner surface of the cell wall. The internal pressure required to rupture the cell walls decreased remarkably during the early to middle stages of growing tip development, but the cell wall hardly extended before rupture. In contrast, during the middle and late stages of development, cell walls were extended by internal pressure. Atomic force microscopy revealed that protease-resistant, fine granular matrix components were present only at the apical portion of a normal growing tip, and were absent in the non-growing cylindrical region. In the early and middle stages of new growing tip development, these matrix components appeared in the cell walls in patches. These results suggest that first cell wall strength decreases and then cell wall extensibility increases in the development of new growing tips, and that protease-resistant, fine granular matrix components may be involved in rendering a cell wall extensible.     

Karyological studies of Iranian <Emphasis Type="Italic">Allium</Emphasis> L. (Amaryllidaceae) species with focus on sect. <Emphasis Type="Italic">Acanthoprason</Emphasis>. 1. Mitotic chromosomes

Eighteen species and subspecies (34 accessions) of Allium sect. Acanthoprason and 11 species (17 accessions) belonging to other subgenera and sections of Allium were karyologically investigated and include first reports for 12 species. The examined plants of 47 accessions were diploid, three accessions of two species were tetraploid, and in the A. bisotunense accession, we found a mix of di- and triploid individuals. B chromosomes were found in 10 accessions. A basic chromosome number of x = 8 was confirmed for all investigated members of subg. Melanocrommyum and subg. Allium, and x = 9 for Allium tripedale of subg. Nectaroscordum. Idiograms were drawn for each accession, and metaphase images are presented illustrating observed chromosomal variations. Also, karyotype features and asymmetry parameters were calculated for all accessions. Chromosomal aberrations, e.g. aneuploid cells or loss of whole or parts of chromosome arms, were rarely observed. In general, the karyotypes showed low variation in inter- and intrachromosomal asymmetry especially inside of the taxonomic groups, though satellited chromosomes were good markers for subgenera and even specific for two studied sections of subg. Allium. Six different types of satellites were recognized, two of them were newly described: Type P was prevalent in subg. Melanocrommyum, and type O in sect. Codonoprasum. Statistical analyses were performed on five karyological parameters to test correct relationships and also to test previous grouping hypotheses. Although our data confirm distinct karyological characters for the subgenera investigated, the remarkable morphological diversity inside of subg. Melanocrommyum is not mirrored by striking karyological differences.     

TGF-beta isoform signaling regulates secondary transition and mesenchymal-induced endocrine development in the embryonic mouse pancreas

Transforming growth factor-beta (TGF-beta) superfamily signaling has been implicated in many developmental processes, including pancreatic development. Previous studies are conflicting with regard to an exact role for TGF-beta signaling in various aspects of pancreatic organogenesis. Here we have investigated the role of TGF-beta isoform signaling in embryonic pancreas differentiation and lineage selection. The TGF-beta isoform receptors (RI, RII and ALK1) were localized mainly to both the pancreatic epithelium and mesenchyme at early stages of development, but then with increasing age localized to the pancreatic islets and ducts. To determine the specific role of TGF-beta isoforms, we functionally inactivated TGF-beta signaling at different points in the signaling cascade. Disruption of TGF-beta signaling at the receptor level using mice overexpressing the dominant-negative TGF-beta type II receptor showed an increase in endocrine precursors and proliferating endocrine cells, with an abnormal accumulation of endocrine cells around the developing ducts of mid-late stage embryonic pancreas. This pattern suggested that TGF-beta isoform signaling may suppress the origination of secondary transition endocrine cells from the ducts. Secondly, TGF-beta isoform ligand inhibition with neutralizing antibody in pancreatic organ culture also led to an increase in the number of endocrine-positive cells. Thirdly, hybrid mix-and-match in vitro recombinations of transgenic pancreatic mesenchyme and wild-type epithelium also led to increased endocrine cell differentiation, but with different patterns depending on the directionality of the epithelial-mesenchymal signaling. Together these results suggest that TGF-beta signaling is important for restraining the growth and differentiation of pancreatic epithelial cells, particularly away from the endocrine lineage. Inhibition of TGF-beta signaling in the embryonic period may thus allow pancreatic epithelial cells to progress towards the endocrine lineage unchecked, particularly as part of the secondary transition of pancreatic endocrine cell development. TGF-beta RII in the ducts and islets may normally serve to downregulate the production of beta cells from embryonic ducts.     

Simultaneous determination of histamine and N tau-methylhistamine with high-performance liquid chromatography using electrochemical detection

We have developed a liquid chromatographic method which uses electrochemical detection for the simultaneous quantitation of histamine and N tau-methylhistamine in rat brain. The amines are derivatized with the water-soluble Bolton-Hunter reagent (sulfo B-H). Perchloric acid extracts of rat brains are chromatographed on a strong cation-exchange resin. The eluate is evaporated and allowed to react with sulfo B-H at pH 9.8 at room temperature. The derivatization is complete after 30 s vortexing. The derivatives are purified using a cellulose-phosphate fibrous cation exchanger. They are quantified with an electrochemical detector at a potential of 0.56 V after preoxidizing the sample at 0.47 V. The derivatives of histamine, N tau-methylhistamine, and N alpha-methylhistamine are completely separated without interfering peaks. Since no N alpha-methylhistamine was detected in rat brain it was used as an internal standard. The detection limits are 0.1 pmol of histamine and 0.2 pmol of N tau-methylhistamine. The precision of this method is high, with within-run and between-run coefficients of variation of 2-7% and linearity of 0.999. Both histamine and N tau-methylhistamine peak heights increased significantly and selectively after treatment with pargyline. Because of the high sensitivity, accuracy, and precision, the histamine and N tau-methylhistamine contents of single nuclei of the rat hypothalamus can be routinely quantified.     

Bicycle spoke injuries in the lower extremity

This study reports the authors' 5-year experience with treating lower extremity injuries in bicycle passengers caused by the spokes. This patient group was selected from 716 lower extremity injuries that received treatment at our outpatient plastic surgery clinic. A total of 26 patients were treated during the study. Patients ranged from 2 to 19 years old, with a mean age of 5.6 years. The authors treated more female passengers (62 percent) than male passengers. The right foot (52 percent) was involved more often than was the left. Most patients were injured in the afternoon, from 2 to 7 PM (62 percent), and between May and October (77 percent). The rear wheel (89 percent) injured the majority of patients. The Achilles tendon was the most common site of injury (63 percent). The typical types of wounds observed included the following: type I, laceration with partial avulsion of skin and subcutaneous tissue (41 percent) and laceration forming a distally based flap (33 percent); type II, abrasions with ecchymoses and friction burn from the shearing effect of the spokes creating a partial- to full-thickness skin defect (26 percent). Of the type I injuries, full-thickness skin lacerations (33 percent) were closed primarily. Partial-thickness skin lacerations, abrasions, ecchymoses, and skin defects (67 percent) were treated conservatively with wound irrigation and dressing. The wound healing time for type I injuries was 29 days; for type II injuries, it was 27 days. These healing times were prolonged compared with healing by first intention. No significant difference was found in healing time when comparing both types of injury. Four patients required hospitalization. No patient required skin grafting. No fractures were noted because these patients were selected from the outpatient plastic surgery clinic and did not include patients from the emergency room. Since the first report of bicycle spoke injuries a half-century ago, prevention has not improved.     

Underwater observations of the rare deep-sea fish <Emphasis Type="Italic">Triodon macropterus</Emphasis> (Actinopterygii,Tetraodontiformes, Triodontidae), with comments on the fine structure of the scales

Underwater observations of two living individuals and an examination of a freshly dead individual of the rare deep-sea fish Triodon macropterus revealed that they usually have the large ventral flap completely uplifted and seamlessly retracted into the abdominal region of the trunk: one individual was collected at a depth of 280 m by hook and line east of Tonaki-jima Island, Ryukyu Islands, and kept in a tank at the Okinawa Churaumi Aquarium for six years; the second living individual was observed by the ROV Hakuyo 2000 at a depth of 275 m east of Ishigaki-jima Island, Ryukyu Islands; and another individual collected at depths of 250?350 m by hook and line off Funchu Point, Yoron-jima Island (27°00.15’N, 128°26.06’E), Ryukyu Islands, provided an opportunity to demonstrate that the ventral flap could be manually uplifted by rotating the pelvis. When the ventral flap was uplifted in all of these specimens, whether naturally or manually, there were no scaleless linear bands or streaks and gaps evident in the skin between the retracted ventral flap and the abdominal region. The fine structure of the scales of the body and the ventral flap was observed by light microscopy, scanning electron microscopy, and X-ray CT scanning. The scales of the ventral flap are arranged in rows radiating from the antero-dorsal part of the ventral flap where the anterior part of the pelvis articulates with and rotates around the pectoral girdles. The orientation of the rows on the ventral flap changes from a posterior direction dorsally to a posteroventral direction more ventrally. A ridge with many sharp serrations is raised and bent from the edge of each scale on the body and ventral flap. The raised ridges on the lower scales on the ventral flap become packed together with the upper scales to form a seamless surface when the ventral flap is uplifted into the abdominal region.     

Nuclear translocation of plk1 mediated by its bipartite nuclear localization signal

Polo-like kinase 1 (Plk1), a mammalian ortholog of Drosophila Polo, is a serine-threonine protein kinase implicated in the regulation of multiple aspects of mitosis. The protein level, activity, and localization of Plk1 change during the cell cycle, and its proper subcellular localization is thought to be crucial for its function. Although localization of Plk1 to the centrosome has been established, nuclear localization or nucleocytoplasmic translocation of Plk1 has not been fully addressed. Here we show that Plk1 accumulates in both the nucleus and the cytoplasm in addition to its localization to the centrosome during S and G(2) phases. Our results identify a conserved region in the kinase domain of Plk1 (residues 134-146) as a functional bipartite nuclear localization signal (NLS) sequence that regulates nuclear translocation of Plk1. The identified NLS is necessary and sufficient for directing nuclear localization of Plk1. This bipartite NLS has an unusually short spacer sequence between two clusters of basic amino acids but is sensitive to RanQ69L, a dominant negative form of Ran, similar to ordinary bipartite NLS. Remarkably, the expression of an NLS-disrupted mutant of Plk1 during S phase was found to arrest the cells in G(2) phase. These results suggest that the bipartite NLS-dependent nuclear localization of Plk1 before mitosis is important for ensuring normal cell cycle progression.     

In vitro and in vivo transferrable beta-lactam resistance due to a new plasmid-mediated oxyiminocephalosporinase from a clinical isolate of Proteus mirabilis

A new plasmid-mediated beta-lactamase (FPM-1) with an isoelectric point of 7.2 and a molecular weight of 26,000 was found in a cefuroxime-resistant clinical isolate of Proteus mirabilis strain 6003. FPM-1 can be classified as a type I oxyimino-cephalosporinase on the basis of its substrate specificity and inhibition pattern by clavulanic acid etc., and its conferred resistance on both the strain and transconjugants against most oxyme-type cephalosporins as well as the older ones but not against cefamycins and a few exceptional oxyme-type cephalosporins such as ceftizoxime, ceftazidime and cefixime. In a murine systemic infection model, only these FPM-1-stable drugs exhibited protective activity against the FPM-1-producing P. mirabilis 6003 similar to that against a nonproducing derivative strain. The FPM-1-mediated cefuroxime resistance in P. mirabilis 6003 was transferred to co-infected Escherichia coli 7004 at frequencies between 3.8 x 10(-3) and 4.0 x 10(-2) in a murine ascending urinary tract infection model. In the same infection model due to the FPM-1-producing E. coli transconjugant, FPM-1-stable cefixime was significantly more effective than FPM-1-labile cefteram pivoxil, although both drugs had similar therapeutic effect against its FPM-1-nonproducing counterpart strain.