Role of the gene 17 protein of bacteriophage T4

Head-related particles of bacteriophage T4 were examined by using heat leakage scanning calorimetry. The 17- particles showed two endothermic peaks on thermograms during their thermal transition process, while 49- particles gave only a single sharp endothermic peak. Thermograms of 17- particles treated with 23- defective lysate were different from those of nontreated 17- particles, and closely resembled thermograms of 49- particles. The 31- defective lysate was also capable of converting thermal properties of 17- particles. These results suggest that there is a structural difference between 17- particles and 49- particles, and that the product gene 17 of bacteriophage T4 is involved in the structural conversion of prohead to a more completed structure.     

Immunopathological correlation between mesangial C3d-deposition and C3d-fixing circulating immune complexes in lupus nephritis

By a direct immunofluorescent technique, glomerular C3d deposition was examined in a total of 50 renal biopsy specimens from patients with lupus nephritis. C3d deposition was then compared with disease activity, glomerular IgG and C3c deposition, and the levels of circulating immune complexes (CIC) measured by a solid-phase anti-C3d assay. There was a good correlation between disease activity and the positivity of glomerular C3d deposits (P less than 0.001), as well as C3c deposits (P less than 0.001). Even in clinically inactive patients, a relatively high percentage (59%) of C3d deposits were positive compared with C3c deposits (17%). Mesangial C3d deposition correlated with clinical disease activity more significantly (P less than 0.005) than capillary wall C3d deposition (P less than 0.025). C3d deposits were detected in all of the 30 cases with positive C3c deposits, and moreover, in 15 of the 20 (75%) cases with negative C3c deposits. Glomerular IgG deposits were almost always associated with C3d deposits, both in mesangial areas and along capillary walls, with statistical significance (P less than 0.005, P less than 0.001, respectively). The serum levels of C3d-fixing immune complexes (IC) were significantly correlated with the positivity and intensity of mesangial C3d deposits. This study demonstrates glomerular deposition of C3d in patients with lupus nephritis and reveals a significant correlation between mesangial C3d deposition and disease activity.     

Interaction between poly(L-lysine) and sulfated poly(vinyl alcohol)

Ionic polymer-polymer interaction was studied in aqueous solution for poly(L -lysine) (PLL) and sulfated poly(vinyl alcohol) (PVS) as functions of pH, the degree of sulfation, the functional unit mole ratio of the two polymers and temperature by means of circular dichroism and viscosity measurements. In all the cases studied, strong inter-polymer complexes were formed at the functional unit mole ratio (VS)/(LL) higher than 1. Although PLL itself is well known to take the α-helical conformation at such a high pH as 11, the PLL conformation in the PLL/PVS complexes did not depend on pH but on the degree of sulfation: at room temperature, PLL took random coil conformation in PLL/PVS-25 (25: degree of sulfation in mole-%) and PLL/PVS-30, and the α-helical conformation (helicity of 70%) in PLL/PVS-46 and PLL/PVS-95. Models for the complex structures are postulated. Methanesulfonic acid did not influence the conformational transition of PLL, supporting that a polymer effect took place in the complex formation between PLL and PVS. Thermal effect on the PLL conformation in the complex is also discussed.     

A practical approach to the clinical diagnosis of Ewing's sarcoma/primitive neuroectodermal tumour and other small round cell tumours sharing EWS rearrangement using new fluorescence in situ hybridisation probes for EWSR1 on formalin fixed, paraffin wax embedded tissue

BACKGROUND: Over 90% of Ewing's sarcoma/primitive neuroectodermal tumour (ES/PNET) cases have the t(11;22) chromosomal rearrangement, which is also found in other small round cell tumours, including desmoplastic small round cell tumour (DSRCT) and clear cell sarcoma (CCS). Although this rearrangement can be analysed by fluorescence in situ hybridisation (FISH) using routinely formalin fixed, paraffin wax embedded (FFPE) tissues when fresh or frozen tissues are not available, a sensitive and convenient detection method is needed for routine clinical diagnosis. AIMS: To investigate the usefulness of newly developed probes for detecting EWS rearrangement resulting from chromosomal translocations using FISH and FFPE tissue in the clinical diagnosis of ES/PNET, DSRCT, and CCS. METHODS: Sixteen ES/PNETs, six DSRCTs, and six CCSs were studied. Three poorly differentiated synovial sarcomas, three alveolar rhabdomyosarcomas, and three neuroblastomas served as negative controls. Interphase FISH analysis was performed on FFPE tissue sections with a commercially available EWSR1 (22q12) dual colour, breakapart rearrangement probe. RESULTS: One fused signal and one split signal of orange and green, demonstrating rearrangement of the EWS gene, was detected in 14 of 16 ES/PNETs, all six DRSCTs, and five of six CCSs, but not in the negative controls. CONCLUSIONS: Interphase FISH using this newly developed probe is sensitive and specific for detecting the EWS gene on FFPE tissues and is of value in the routine clinical diagnosis of ES/PNET, DSRCT, and CCS.     

Effect of ionic strength on crossbridge kinetics as studied by sinusoidal analysis,ATP hydrolysis rate and x-ray diffraction techniques in chemically skinned rabbit psoas fibres

Summary In order to identify which steps in the crossbridge cycle are affected by changes in ionic strength, we studied the effect of ionic strength on the rate constants and magnitudes of three exponential processes, the ATP hydrolysis rate and isometric tension during maximal activation (pCa 4.52, 5 mM MgATP). Equatorial X-ray diffraction measurements were also carried out in both relaxing and rigor conditions to examine whether the distance between thick and thin filaments changes with ionic strength (range: 100–300 mM). All experiments were carried out at 20° C and at pH 7.0 on chemically skinned rabbit psoas muscle fibres. Isometric tension and muscle stiffness declined significantly as the ionic strength was increased from 150 mM to 300 mM. The concomitant decrease in the ATP hydrolysis rate was much less than tension, resulting in a large increase in the tension cost. Three rate constants of exponential processes, deduced from sinusoidal analysis, did not change appreciably. The magnitude parameters of all three processes diminished as the ionic strength was increased. During relaxation the filament spacing increased by 5% when the ionic strength was increased from 150 mM to 300 mM. After rigor induction, the spacing did not change with ionic strength. We conclude that a change in ionic strength modifies the rapid equilibrium between the detached state and the weakly attached state, and that this causes considerable effect on isometric tension. We also conclude that other steps in the crossbridge cycle are less sensitive to ionic strength, and that the lattice spacing change is unable to account for the considerable effect of ionic strength on isometric tension.     

Differential expression of glutamate receptors in Xenopus oocytes injected with messenger RNA from lobster muscle

In the neuromuscular synapse of lobster walking leg, application of glutamate and its agonists generated transient depolarization of the postsynaptic membrane. The order of potency was quisqualate greater than glutamate greater than kainate. NMDA was inactive on lobster muscle. However, the membrane of Xenopus oocytes injected with mRNA from lobster muscle acquired sensitivity to NMDA. The order of potency for inducing current responses in the oocyte membrane was kainate greater than glutamate = NMDA much greater than quisqualate. The results suggest that mRNAs coding for glutamate receptors in the lobster muscle are expressed differently in Xenopus oocyte membrane.