Minor daphnane-type diterpenoids from Wikstroemia retusa

In addition to huratoxin, pimelea factor P2, and wikstroelides A-G from the fresh bark, eight daphnane-type diterpenoids, wikstroelides H-O, were isolated from the bark and stem, and their structures established. Cytotoxicity was assayed on some wikstroelides.     

Phosphorylation-dependent reversible translocation of Ca2+/calmodulin-dependent protein kinase II to the postsynaptic densities

The translocation of soluble Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) to postsynaptic densities (PSDs) was investigated. When soluble CaM kinase II previously autophosphorylated was incubated with PSDs, the kinase was precipitated by centrifugation, indicating that the soluble kinase associated with PSDs and formed a PSD-CaM kinase II complex. Ca2+-independent activity generated by autophosphorylation of the kinase was retained in the complex. A number of PSD proteins were phosphorylated by the kinase associated with PSDs in both the absence and presence of Ca2+. When PSD-CaM kinase II complex was incubated at 30 degrees C, the enzyme was dephosphorylated and released from the complex. These results indicate that CaM kinase II reversibly translocates to PSDs in a phosphorylation-dependent manner.     

Backfire mode zigzag antenna

A backfire mode zigzag antenna is analysed using the method of moments. The effects of the filament length of the zigzag on the -10 dB beam width is calculated. The zigzag antenna is applied to a symmetrical paraboloidal reflector antenna as a primary feed. The reflector antenna shows a relatively constant gain in the communication satellite frequency band 12.25-2.75 GHz.<>     

The influence of proteins on the fretting-corrosion behaviour of a Ti6Al4V alloy

The effects of collagen and albumin on the fretting-corrosion behaviour of a Ti6Al4V alloy contacting an Al₂O₃ counter-piece was investigated in pH buffered saline solutions at 37 °C using a tribo-electrochemical apparatus. Phosphate ion and hydroxyethyl-piperazinyl-ethanesulfonic acid (HEPES) were used as the pH buffer agents. Tests were conducted under two applied electrochemical potentials and two loads. Potentiodynamic polarisation curves were measured to assess the effect of proteins and pH buffer agents on the corrosion behaviour. Surfaces were characterised by XPS analysis, secondary electron spectroscopy and laser profilometry.Fretting wear of the Ti6Al4V alloy increased with increasing applied potential and load but was not significantly affected by the presence of collagen or albumin. Only a small lubricant effect of collagen could be observed at cathodic potentials. In phosphate buffer saline (PBS) solutions, those proteins were found to act as cathodic inhibitor by shifting the corrosion potential and the cathodic current towards more cathodic values. Phosphate ions were found to be incorporated on the Ti6Al4V alloy and to cause sedimentation of wear particles around the wear trace. In HEPES solutions wear particles were dispersed away from the wear trace.     

Viral respiratory infection causes airway hyperresponsiveness and decreases histamine N-methyltransferase activity in guinea pigs

We investigated the effects of viral respiratory infection by Sendai virus on bronchial responses to aerosolized histamine in anesthetized guinea pigs and on the activity of histamine N-methyltransferase (HMT). We measured the change in total pulmonary resistance induced by histamine in the presence or absence of a specific HMT inhibitor, SKF 91488, in noninfected and infected animals. In the absence of SKF 91488, the bronchoconstrictor response to histamine was greater in infected than in noninfected animals. SKF 91488 (10(-2) M, 90 breaths) potentiated the responses to histamine in noninfected animals, and the magnitude of augmented responses to histamine by SKF 91488 was similar to that by viral infection. Furthermore, SKF 91488 did not further potentiate the responses to histamine in infected animals. However, responses to aerosolized acetylcholine were unaffected by viral infection and SKF 91488. The HMT activity decreased by 56% in the trachea, 86% in the bronchi, and 52% in the parenchymal tissue in the infected animals. In contrast to HMT activity, acetylcholinesterase activity was unaffected by viral infection. These results suggest that respiratory infection by Sendai virus causes enhanced bronchial responsiveness to histamine by decreasing HMT activity in airways.     

An unusual presentation of congenital infantile myofibromatosis arising from the interspinous ligament

The authors describe an extremely rare presentation of congenital infantile myofibromatosis. A full-term newborn boy presented with a thumb-sized subcutaneous mass on the mid-spinal line between the 2nd and 3rd lumbar spinous processes. A solid tumor arising from the interspinous ligament was resected. Microscopic and immunohistochemical studies revealed myofibromatosis.     

Atrophy of the corpus callosum associated with cognitive impairment and widespread cortical hypometabolism in carotid artery occlusive disease

BACKGROUND: The independent influences of small-intestinal bacterial overgrowth and old age on mucosal immunoglobulin production and secretion have not been assessed. This is an important issue, since luminal IgA deficiency may exacerbate small-intestinal bacterial overgrowth, the prevalence of which is high in selected elderly populations. METHODS: Proximal small-intestinal aspirates were obtained from 33 subjects for bacteriologic analysis and measurement of total IgA, IgM, total IgG. IgG subclass, and IgD concentrations. IgA subclasses were measured in 24 unselected subjects. Serum immunoglobulin and salivary IgA concentrations were measured in all subjects. RESULTS: IgA2 and IgG3 were predominant IgA and IgG subclasses in proximal small-intestinal luminal secretions. Luminal concentrations of IgA2 and IgM, but not IgG3 or any other IgG subclass, were significantly increased in small-intestinal bacterial overgrowth, which was present in 19 of 33 (57.6%) subjects. Old age did not influence these levels. Luminal immunoglobulin concentrations did not correlate significantly with either serum or salivary values. IgD was not measureable in proximal small-intestinal secretions. CONCLUSIONS: Increased luminal concentrations of the secretory immunoglobulins, IgA2 and IgM, occur in small-intestinal bacterial overgrowth. Local investigation is mandatory when assessing the mucosal immunopathology of this disorder. Luminal IgG3 is unlikely to be predominantly derived from serum. Old age does not independently influence luminal immunity.     

Delayed neuropathy and inhibition of soluble neuropathy target esterase following the administration of organophosphorus compounds to hens

BACKGROUND: Disulfide exchange reactions are catalyzed by thiol/disulfide oxidoreductases. These enzymes possess a thioredoxin fold and contain a catalytic disulfide with the sequence Cys-X-X-Cys at the N terminus of an alpha helix. Despite these similarities, the various members differ strongly in their redox potentials (-122 mV to -270 mV). Using the strong oxidant DsbA from Escherichia coli as a model system, we investigated whether the redox properties of these enzymes can be modulated rationally by exchange of the X-X dipeptide. RESULTS: The X-X dipeptide of DsbA (Cys30-Pro31-His32-Cys33) was exchanged by the dipeptides of eukaryotic protein disulfide isomerase (PDI; Gly-His), glutaredoxin (Pro-Tyr), and thioredoxin (Gly-Pro) from E. coli. All variants were less oxidizing than wild-type DsbA and their redox potentials were in the order of the related natural enzymes (DsbA > PDI > glutaredoxin > thioredoxin). The equilibrium constant between glutathione and the thioredoxin-like variant increased 1200-fold compared with wild-type DsbA. The variants also showed a strong increase in the pKa of the nucleophilic cysteine (Cys30). As for glutaredoxin and thioredoxin, the catalytic disulfide stabilized the corresponding variants while destabilizing wild-type DsbA and the PDI-like variant. CONCLUSIONS: The X-X dipeptide in the active site of thiol/disulfide oxidoreductases appears to be the main determinant of the redox properties of these enzymes. This empirical finding should be very useful for the design of new thiol/disulfide oxidoreductases with altered redox potentials and for studying the function of these enzymes in vivo.     

Potassium depletion modulates aldose reductase mRNA in rat renal inner medulla

The organic osmolytes present in renal inner medullary cells balance the extracellular hyperosmolality and protect the cell against the effects of high salts and urea. We previously demonstrated that a renal concentrating defect due to potassium depletion was associated with a decrease in organic osmolytes including sorbitol. However, we could not determine whether a reduction in medullary organic osmolyte would be cause or effect of urine concentration defect associated with potassium depletion. We focused on the synthesis of sorbitol catalyzed by the enzyme, aldose reductase. To clarify whether the treatment of potassium depletion would affect aldose reductase when extracellular tonicity, and medullary sodium or potassium was maintained at the level of control rats, we administered a hypertonic solution of NaCl or KCl to potassium-depleted rats and evaluated aldose reductase enzymatic activity and mRNA abundance as well as the medullary contents of organic osmolytes. Either infusion significantly reduced tissue sodium content in potassium-depleted rats. With KCl infusion protocol but not that of NaCl, sorbitol as well as aldose reductase mRNA abundance increased to the control level. Medullary contents of other organic osmolytes exhibited a pattern similar to sorbitol. Data suggested that aldose reductase mRNA abundance was reduced in potassium depletion irrespective of medullary sodium content. A decrease in sorbitol level may precede a urinary concentrating defect. Our finding constitutes the first demonstration of the relationship between a potassium deficiency and the abundance of aldose reductase mRNA, an osmoregulatory protein in the kidney.