Heparin potentiates the action of plasma membrane-associated growth stimulatory activity

Plasma membranes prepared from mouse liver have been previously shown to contain growth stimulatory activity as determined with cultured mouse fibroblasts. This growth stimulatory activity, termed plasma membrane-associated growth stimulatory activity (PMGA), is highly mitogenic in the presence of platelet-poor plasma. We now demonstrate that the growth stimulatory action of PMGA is dramatically enhanced by the addition of heparin. The half-maximal effect of heparin was observed at 1-3 micrograms/ml. The synergistic effect was seen in two distinct assays; the stimulation of DNA synthesis in quiescent cells, and an increase of cell number over a 3-day culture period. Heparin, by itself, does not have any measurable influence on the growth of fibroblasts. The action of heparin is not unique to this glycosaminoglycan, as several other highly sulfated polysaccharides, including dextran sulfate, pentosan polysulfate, and fucoidan, also exhibited the highly synergistic effect. Among other glycosaminoglycans examined, chondroitin sulfate B and heparan sulfate had a small, but significant, effect on enhancing the growth stimulatory action of PMGA. Chondroitin sulfate A, chondroitin sulfate C, hyaluronic acid dextran, and poly-L-glutamic acid, however, had no detectable effect. Further experiments suggested that the effect of heparin is twofold, namely, both a potentiation of growth stimulatory activity and a protection of PMGA activity. The data presented here suggest that the association of various cell surface components, such as PMGA and specific proteoglycans, can modulate the growth potential of a cell.     

Attenuating effect of diazepam on stress-induced increases in noradrenaline turnover in specific brain regions of rats: antagonism by Ro 15-1788

One-hour immobilization stress increased levels of the major metabolite of brain noradrenaline (NA), 3-methoxy-4-hydroxyphenyl-ethyleneglycol sulfate (MHPG-SO4), in nine brain regions of rats. Diazepam at 5 mg/kg attenuated the stress-induced increases in MHPG-SO4 levels in the hypothalamus, amygdala, hippocampus, cerebral cortex and locus coeruleus (LC) region, but not in the thalamus, pons plus medulla oblongata excluding the LC region and basal ganglia. The attenuating effects of the drug on stress-induced increases in metabolite levels in the above regions were completely antagonized by pretreatment with Ro 15-1788 at 5 or 10 mg/kg, a potent and specific benzodiazepine (BDZ) receptor antagonist. When given alone, Ro 15-1788 did not affect the increases in MHPG-SO4 levels. Behavioral changes observed during immobilization stress such as vocalization and defecation, were also attenuated by diazepam at 5 mg/kg and this action of diazepam was antagonized by Ro 15-1788 at 10 mg/kg, which by itself had no effects on these behavioral measurements. These findings suggest: (1) that diazepam acts via BDZ receptors to attenuate stress-induced increases in NA turnover selectively in the hypothalamus, amygdala, hippocampus, cerebral cortex and LC region and (2) that this decreased noradrenergic activity might be closely related to relief of distress-evoked hyperemotionality, i.e., fear and/or anxiety in animals.     

Growth Characteristics and Intraspecies Host Specificity of a Large Virus Infecting the Dinoflagellate Heterocapsa circularisquama

The growth characteristics and intraspecies host specificity of Heterocapsa circularisquama virus (HcV), a large icosahedral virus specifically infecting the bivalve-killing dinoflagellate H. circularisquama, were examined. Exponentially growing host cells were more sensitive to HcV than those in the stationary phase, and host cells were more susceptible to HcV infection in the culture when a higher percent of the culture was replaced with fresh medium each day, suggesting an intimate relationship between virus sensitivity and the physiological condition of the host cells. HcV was infective over a wide range of temperatures, 15 to 30°C, and the latent period and burst size were estimated at 40 to 56 h and 1,800 to 2,440 infective particles, respectively. Transmission electron microscopy revealed that capsid formation began within 16 h postinfection, and mature virus particles appeared within 24 h postinfection at 20°C. Compared to Heterosigma akashiwo virus, HcV was more widely infectious to H. circularisquama strains that had been independently isolated in the western part of Japan, and only 5.3% of the host-virus combinations (53 host and 10 viral strains) showed resistance to viral infection. The present results are helpful in understanding the ecology of algal host-virus systems in nature.     

Phosphoenolpyruvate:carbohydrate phosphotransferase systems in Enterococcus faecalis

A wild-type strain of Enterococcus faecalis and its mutants resistant to 2-deoxy-D-glucose (2DG) were examined for the presence of phosphoenolpyruvate:carbohydrate phosphotransferase systems (PTSs) with 12 carbohydrates, which were utilized by the organism, as the substrates. The wild-type strain possessed a constitutive mannose-PTS, which was reactive with glucose, mannose, glucosamine, 2DG and fructose. This activity was absent in the mutants. No independent glucose- or fructose-PTS was found in the mannose-PTS-defective mutants. The mutants, however, showed a low level of a constitutive PTS activity with maltose, suggesting the existence of an independent maltose-PTS in the organism. Both wild-type and mutant strains possessed inducible lactose-, mannitol-, and trehalose-PTSs. Lactose-PTS was induced by either lactose or galactose in the parent, but only by lactose in the mutants. The lactose-PTS was not reactive with galactose, and no separate galactose-PTS was present. These observations suggest that the inducer for lactose-PTS, probably being galactose 6-phosphate, may not be formed from galactose in the organism when the constitutive mannose-PTS is lost by mutation.     

Parathyroid hormone-related protein is a possible autocrine growth inhibitor for lymphocytes

Adult T-cell leukemia (ATL)-related cells have the ability to produce a newly-isolated calcium-regulating protein, parathyroid hormone-related protein (PTHrP). The present study revealed that lectin-stimulated normal lymphocytes produce immunoreactive (IR)-PTHrP. When the T-cell-enriched fraction was purified from normal lymphocytes and then treated with lectin, a similar amount of IR-PTHrP was detected, suggesting that IR-PTHrP is an actual product of T-lymphocytes. A biologically active fragment of PTHrP, PTHrP(1-34), suppressed DNA synthesis in lectin-stimulated lymphocytes at concentrations greater than 50 pg/mL; the same concentration range of IR-PTHrP detected in the cultured media of lectin-stimulated lymphocytes. Therefore, it is reasonable to postulate that PTHrP is a cytokine inhibiting the cellular growth of normal lymphocytes.     

Audio-Visual Perception of 3D Cinematography: An fMRI Study Using Condition-Based and Computation-Based Analyses

The use of naturalistic stimuli to probe sensory functions in the human brain is gaining increasing interest. Previous imaging studies examined brain activity associated with the processing of cinematographic material using both standard “condition-based” designs, as well as “computational” methods based on the extraction of time-varying features of the stimuli (e.g. motion). Here, we exploited both approaches to investigate the neural correlates of complex visual and auditory spatial signals in cinematography. In the first experiment, the participants watched a piece of a commercial movie presented in four blocked conditions: 3D vision with surround sounds (3D-Surround), 3D with monaural sound (3D-Mono), 2D-Surround, and 2D-Mono. In the second experiment, they watched two different segments of the movie both presented continuously in 3D-Surround. The blocked presentation served for standard condition-based analyses, while all datasets were submitted to computation-based analyses. The latter assessed where activity co-varied with visual disparity signals and the complexity of auditory multi-sources signals. The blocked analyses associated 3D viewing with the activation of the dorsal and lateral occipital cortex and superior parietal lobule, while the surround sounds activated the superior and middle temporal gyri (S/MTG). The computation-based analyses revealed the effects of absolute disparity in dorsal occipital and posterior parietal cortices and of disparity gradients in the posterior middle temporal gyrus plus the inferior frontal gyrus. The complexity of the surround sounds was associated with activity in specific sub-regions of S/MTG, even after accounting for changes of sound intensity. These results demonstrate that the processing of naturalistic audio-visual signals entails an extensive set of visual and auditory areas, and that computation-based analyses can track the contribution of complex spatial aspects characterizing such life-like stimuli.     

Formation of Coenzyme Q11 by Pseudomonas M16, a Mutant

Pseudomonas M16 is the mutant derived from a facultative methylotroph, Pseudomonas N842, which is the potent producer of coenzyme Q₁₀ (CoQ₁₀). This mutant with elevated productivity of CoQ₁₀ was observed to accumulate the significant amount of another CoQ homolog, which could not be detected in the parent strain. This CoQ homolog was extracted from the intact cells of the mutant and purified to crystaline state. The chemical properties and the results of UV, NMR and mass spectrometries revealed that this CoQ homolog was CoQ₁₁.