Membrane lipids of Rhodopseudomonas viridis

In search of the precyanobacterial origin of the typical thylakoid lipids found in cyanobacteria and chloroplasts, we analyzed the polar lipids of the anaerobic phototrophic bacterium Rhodopseudomonas viridis. Glycolipids (monogalactosyl-, digalactosyl- and glucuronosyl diacylglycerol), phospholipids (phosphatidyl choline, -ethanolamine, -glycerol and cardiolipin) and an ornithine lipid were isolated and identified by NMR (1H, 13C, 31P) and mass spectrometry. Positional distribution and pairing of fatty acids in molecular species show small, but significant differences between glyco- and phospholipids. In this context, a new enzymatic method is described for assigning the enantiomeric structure of the diacylglycerol moiety in glyco- and phospholipids. 14C-Labelling studies suggest that monogalactosyl diacylglycerol is formed by galactosylation of diacylglycerol as in chloroplasts and not by glucosylation followed by epimerization as in cyanobacteria. The two 1,6-linked galactopyranose residues of digalactosyl diacylglycerol are both in beta-linkage and thus differ from the corresponding chloroplast lipid with its alpha-beta-sequence. R. viridis does not contain the sulfolipid, and even phosphate starvation does not induce the synthesis of this most characteristic thylakoid lipid, which on the other hand is present in other anaerobic phototrophic bacteria.     

The 802.3z Gigabit Ethernet Standard

Considers standards development in the IEEE 802.3z Gigabit Ethernet Task Force, part of the IEEE 802.3 CSMA/CD Working Group. IEEE Std 802.3z-1998 was formally approved by the IEEE Standards Board on June 25th, 1998. IEEE Std 802.3z, extends the operating speed of the world's most popular local area network to 1 billion bits per second (1000 Mb/s) for interconnecting high-performance switches, routers, and servers in the backbone of local area networks. Maintaining backward compatibility with the over-100-million-node installed base of 10 Mb/s and 100 Mb/s was a key requirement     

The results of radiotherapy for ependymomas: the Mayo Clinic experience

It is known that exogenous 11-cis-retinol inhibits the recovery of photosensitivity of bleached rod outer segments (ROS) and 11-cis-retinol exists in the interphotorecepter matrix. We examined the conversion of 11-cis-retinol with bovine ROS. ROS was incubated with 11-cis-retinol under dim red light. Retinoids were extracted from the reaction mixture with hexane and analyzed by HPLC coupled with a fluorescence spectrophotometer. Isomerization of 11-cis-retinol to all-trans-retinol was observed in the presence of ROS. This isomerization was not suppressed by heat treatment and did not have stereospecificity. In addition, we incubated purified rhodopsin and phospholipids extracted from ROS with 11-cis-retinol. Rhodopsin was found to isomerize 11-cis-retinol to all-trans-retinol as well as ROS, but phospholipids did not. In contrast, the phospholipids inhibited the isomerization of 11-cis-retinol to all-trans-retinol by the purified rhodopsin. Commercially available phospholipids, especially phosphatidylserine, also inhibited the isomerization. Our results suggest that rhodopsin has activity for the isomerization of 11-cis-retinol to all-trans-retinol and may play an important role in the detoxification of 11-cis-retinol in the ROS.     

Spermine-mediated phosphorylation of RNA polymerase I and its effect on transcription

A nuclear protein kinase, designated NII, was purified essentially to homogeneity from the Morris hepatoma 3924A. In the presence of excess Mg2+, phosphorylation of casein by the kinase was stimulated by spermine (1-5 mM) and was inhibited completely by 0.1 microgram/ml heparin. The apparent Km for casein was reduced in the presence of spermine. Spermine preferentially augmented phosphorylation of threonine residues. The kinase was also associated with highly purified RNA polymerase I and appears to correspond to two polypeptides (Mr 42,000 and 24,600) of the polymerase. RNA polymerase I polypeptides of Mr 120,000 (S2), Mr 65,000 (S3) and Mr 24,600 (S5) were phosphorylated by the endogenous kinase. Spermine enhanced phosphorylation of the RNA polymerase I subunits as much as 20-fold. Phosphorylation activated RNA polymerase I; the phosphorylated enzyme synthesized longer product with no apparent effect on the number of RNA chains initiated.     

Black Creek Canal Virus infection in Sigmodon hispidus in southern Florida

Flexor pulleys in the hindpaw digits of twenty-eight adult mixed-breed dogs were reconstructed in order to investigate the influence, on the reconstruction, of the source of the autogenous tissue (intrasynovial compared with extrasynovial tendon) and the tension applied during the repair. The ipsilateral peroneus longus tendon was used to reconstruct the A2 pulley with an around-the-bone technique in twenty-one digits; the graft was sutured at a tension of 0.49, 0.98, and 1.96 newtons in seven digits each. The flexor digitorum profundus tendon of an adjacent digit was used to reconstruct the A2 pulley, at a tension of 0.98 newton, in seven additional digits. The contralateral digits were used as controls for all twenty-eight treated digits. The digits were tested in a custom apparatus designed to measure the frictional force generated between the reconstructed pulley and the tendon beneath it. The frictional force did not differ significantly (p > 0.5) among the three groups repaired with peroneus longus tendon; however, the average value was more than five times that produced in the contralateral, control digits. The average frictional forces created by the flexor digitorum profundus grafts were similar to those in the contralateral, control digits. Reconstruction with the flexor digitorum profundus at a tension of 0.98 newton produced significantly less frictional force (p < 0.05) than that produced by the peroneus longus graft at the same tension. This in vitro model of reconstruction of the A2 pulley demonstrated that tendon from an intrasynovial source (the flexor digitorum profundus) produced less frictional resistance to gliding of the tendon than did tendon from an extrasynovial source (the peroneus longus). This result is consistent with previously published findings that intrasynovial tendons may make better grafts than extrasynovial tendons for the reconstruction of gliding flexor tendons because of decreased friction and better healing qualities. Intrasynovial tendons may also make better grafts for the reconstruction of flexor pulleys.     

Presentation, treatment, and outcome of local recurrence afterskin-sparing mastectomy and immediate breast reconstruction

To evaluate the relative role of plasma and platelet von Willebrand factor (vWF) pools in hemostasis and arterial thrombogenesis, pigs with vW disease (vWD) were injected with vWF concentrate and/or grafted with bone marrow from a normal pig. Hemostasis was assessed by measurement of ear immersion bleeding time, factor VIII (FVIII) activity, and plasma and platelet vWF antigen levels. The thrombotic process was explored at 650 s(-1) and 1600 s(-1) in an ex vivo cylindrical perfusion chamber. Pigs with vWD exhibited a prolonged bleeding time (>30 minutes) compared with normal pigs (<5 minutes); in addition, they showed normal platelet adhesion and thrombus formation at 650 s(-1) but profoundly reduced platelet adhesion and thrombus formation at 1600 s(-1). Each experiment was performed before and 3 and 24 hours after injection of vWF concentrate. In our bleeding time study, only plasma vWF restoration induced a partial but delayed correction (24 hours postinjection), which was correlated with the highest measured level of FVIII activity. In the perfusion chamber model, restoration of plasma or platelet vWF pools resulted in similar partial correction of platelet adhesion and average thrombus size. In the perfused pigs, the maximum correction occurred 3 hours postinjection. Platelet deposition reached normal values after vWF concentrate was injected into a grafted pig. The present results suggest that when both plasma and platelet vWF levels are restored in vWD pigs, bleeding time and the thrombotic process are normalized according to different kinetics and with differing degrees of effectiveness.     

Victim attributions and post-rape trauma.

This study assessed (a) the kinds of attributions victims make, (b) whether behavioral and characterological self-blame are associated with other variables as hypothesized (e.g., perception of future avoidability of being raped), and (c) whether behavioral self-blame is associated with better post-rape adjustment (R. Janoff-Bulman; see record 1981-01320-001). Attributions and adjustment were assessed in a sample of adult female rape victims seen at a hospital-based rape crisis program. Many victims blamed themselves but tended to place more blame on external factors. The pattern of relations between behavioral and characterological self-blame and other attributional measures did not support the hypothesized distinctions between them. Both kinds of self-blame were significantly associated with increased post-rape depression. Attributions strongly predicted adjustment, accounting for up to 67% of the variance in 3-day post-rape depression. The theoretical and clinical implications of these findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)