Protection of mice against Sendai virus pneumonia by non-neutralizing anti-F monoclonal antibodies

Nine monoclonal antibodies (MAbs) directed to F protein of Sendai virus were obtained and characterized for their protective ability against Sendai virus infection in mice. None of the MAbs showed hemagglutination-inhibition (HI), hemolysis-inhibition (HLI), or neutralization (NT) activities in vitro when assayed by standard methods. Some of the MAbs, however, showed complement-requiring NT (C-NT) and complement-requiring hemolysis (C-HL) activities when assayed in the presence of complement. Passive immunization experiments revealed that the MAbs with higher C-NT and C-HL activities showed protective activity against Sendai virus pneumonia in mice, and that some MAbs with IgG1 isotype having neither C-NT nor C-HL activity also showed the protective activity. Digestion of the MAbs with pepsin which split immunoglobulin molecules into F(ab')2 and Fc fragments greatly suppressed the protective activity. These results suggest that not only complement-mediated immunological responses such as immune virolysis but also antibody-dependent cellular cytotoxicity (ADCC) and/or immune phagocytosis, in which complement system is not necessarily involved, play an important role in the protection of mice from Sendai virus infection.     

Denaturation of bacteriorhodopsin by organic solvents

The denaturation of bacteriorhodopsin by various organic solvents was studied using absorption, circular dichroism (CD) and fluorescence measurements. Organic solvents with a hydrogen-bonding group caused the release of retinal. The CD measurements showed that the helical structure was maintained even in the denatured state, whereas its tertiary structure was destroyed. The change in fluorescence intensity of tryptophan and fluorescent retinal also confirmed that the tertiary structure was destroyed. Comparison of the denaturation efficiency of various organic solvents showed that the concentration at denaturation was inversely proportional to the partition coefficient of the denaturant. This inverse proportionality clearly indicated that denaturation was determined by the concentration of denaturants which partitioned into the hydrophobic region of the membrane. It was discussed from the experimental results that the tertiary structure of bacteriorhodopsin was stabilized by the hydrogen-bonding networks between side chains of the helices. The results obtained from analysis of the amino acid sequence were also consistent with the hydrogen-bonding mechanism for the formation of the tertiary structure.     

Replication of ColE2 and ColE3 plasmids: Two ColE2 incompatibility functions

Summary We have identified and localized two incompatibility determinants (IncA and IncB) within a 1.3 kb segment of ColE2 sufficient for autonomous replication. The IncA determinant is localized in a region shorter than 250 bp and expresses incompatibility against both ColE2 and ColE3. The region which determines sensitivity to the IncA determinant seems to overlap with the region specifying the IncA determinant. The expression of the trans-acting factor(s) specifically required for replication of ColE2 interferes with expression of the IncA determinant against ColE2 but not against ColE3. The IncA determinant might be at least partly responsible for the copy number control of the plasmid. The IncB determinant is localized in a 50 bp region (origin) which is sufficient for initiation of replication in the presence of the trans-acting factor(s). The IncB determinant is specific for ColE2 and seems to be due to titration of the trans-acting essential replication factor(s) by binding.     

Effects of hypobaric-hypoxia on the total number and histochemical properties of the soleus muscle fibers and motoneurons in the rat

After 7 weeks of hypobaric-hypoxia adaptation, horseradish peroxidase was injected into the soleus muscle to label motoneurons of the spinal cord in rats. Fiber type distribution in the soleus muscle and oxidative enzyme activity of motoneurons innervating the soleus muscle were examined. Fiber type was converted from slow-twitch-oxidative (SO) to fast-twitch-oxidative-glycolytic (FOG). Oxidative enzyme activity of motoneurons (25-45 micron soma diameter) was increased. However, oxidative capacity of larger motoneurons (greater than or equal to 45 micron soma diameter) was not changed. These data suggest that the lack of increase in oxidative capacity of larger motoneurons (innervating SO units) by hypoxia secondarily causes fiber type shift from SO to FOG.     

Development of cellulose synthesizing complexes inBoergesenia andValonia

Summary The development of linear cellulose synthesizing complexes (=TCs) of two selected siphonocladalean algae,Boergesenia forbesii andValonia ventricosa was investigated by following the time course of the regeneration of cell walls with the freeze fracture technique after aplanospore induction. The following structural changes of TC development were examined: (1) TCs initiatede novo; (2) the first nucleation of TC subunits occurs within 2 hr inBoergesenia and 5 hr inValonia after aplanospore induction, immediately followed by the assembly of cellulose microfibrils; (3) TCs increase their length during the assembly of randomly oriented microfibrils; and, (4) TCs stop increasing in length after the assembly of ordered microfibrils begins, with some time lag. The data demonstrate that linear TCs are not artificial products but dynamic entities which are involved in the assembly of cellulose microfibrils.     

Intraoperative imprint cytology of the thyroid gland with computer-assisted morphometric analysis of cell clusters

Imprint preparations were used in addition to frozen sections in the intraoperative diagnosis of 37 cases of benign and malignant lesions of the thyroid gland, including adenomatous goiter, follicular adenoma, follicular carcinoma and papillary carcinoma. In the imprints, the cytologic features specific for carcinoma, as compared with benign lesions, were (1) the folding of the nuclear contour, (2) the increased density of the cytoplasmic matrix and (3) the frequent appearance of cell clusters of larger size. The size and frequency of cell clusters were morphometrically analyzed by a computer image analyzer. There was an increasing number of large clusters, plus the appearance of clusters of more than 300 micron in diameter, in both follicular and papillary carcinoma. In benign lesions, on the contrary, the majority of cells were isolated or in small clusters, the diameter of which never exceeded 300 micron in diameter. These results demonstrate that (1) the imprint cytology of the thyroid gland is useful in making a rapid intraoperative diagnosis and (2) the introduction of computer-assisted quantitative analysis is of practical value in the diagnosis of malignancy.     

Protective effect of cerulein on memory impairment induced by protein synthesis inhibitors in rats.

Previous studies have demonstrated that NMDA receptor antagonists and protein kinase C inhibitors induced marked memory impairment in rats, but that peripherally administered cerulein (CER) prevented these effects. In the present study, the effect of subcutaneously administered CER on amnesia induced by protein synthesis inhibitors was examined in passive and active avoidance responses and in the Morris water maze test. Intraperitoneal injection of the inhibitors produced marked memory impairment, but the effect was abolished by combined administration with CER. The effective dose of subcutaneously injected CER was, on a molar basis, three thousand- and six thousandfold less than the dose of anisomycin, and two hundred eighty- and three thousandfold less than the dose of puromycin in the passive and active avoidance response experiments, respectively. Similarly, in the Morris water maze test, behavioral disturbances produced by the protein synthesis inhibitors were abolished by CER. These results indicate the effectiveness of CER in preventing memory impairment induced by protein synthesis inhibitors.