Membrane-free scrapie activity.

Determinations of scrapie activity in subcellular fractions from infected hamster brains through the asymptomatic and symptomatic course of infection revealed the presence of substantial amounts of scrapie infectivity in the 100,000 X g supernatant fractions, indicating that association with physically discernible membrane structures is not necessary for the transmission of the scrapie agent. An increase of scrapie infectivity in the 100,000 X g supernatant fractions after vigorous homogenization of infected membrane-rich fractions suggests that the agent is identical in membrane-rich and 100,000 X g supernatant fractions.     

Biological activity of synthetic subunits of streptococcus peptidoglycan. I. Pyrogenic and thrombocytolytic activity.

The ability of some synthetically prepared analogues of Streptococcus peptidoglycan subunits (dipeptide, tetrapeptide, glycodipeptide and glycotetrapeptide) to cause fever in rabbits and lysis of rabbit blood platelets was studied. While di- and tetrapeptides did not exhibit these activities, glycodipeptides and glycotetrapeptides displayed pyrogenic and thrombocytolytic activities comparable with those of natural peptidoglycans.     

Cytotoxic activity of lymphocytes. VIII. Lymphotoxin activity in cell-free extracts of activated lymphocytes.

Cell-free extracts of human lymphocytes activated by PHA contain a cytotoxin that kills mouse L cells. Such cells elaborate two different kinds of toxins into the culture supernatant fluids, called α- and β-lymphotoxin (-LT), which differ in size, stability, and antigenicity. The amount of intracellular toxin is 1 to 24% of that found in supernatants of different tonsil donors. Equal amounts of intracellular toxin appear in both microsomal fraction (100,000g pellet) and soluble supernatant fractions of the cell-free extracts (CFE). The toxin can be solubilized from the membrane by digestion with papain or extraction with a nonionic detergent, but not by repeated sonication. The molecular weight of both the microsomal and soluble cellular cytotoxin is 45,000 ± 5000. The intracellular toxin differs from the extracellular toxins secreted by the same cells in two major characteristics: one, although its size approximates that of supernatant β-LT (and is smaller than the 76,000 M_r α-LT), antibody-inhibiting α-LT but not β-LT inhibits both the microsomal and soluble CFE-LT. Two, the intracellular LT does not display the charge heterogeneity so characteristic of supernatant α-LT. Supernatant α-LT and CFE-LT are similar in their patterns of inactivation by heating to 80 °C and treatments with sodium dodecylsulfate (SDS), guanidine, proteases, and heavy metal ions, and are similarly unaffected by treatment with 8 M urea, N-ethylmaleimide, and sodium periodate. These results suggest that the single polypeptide intracellular LT is the precursor of the more complex secreted α-LT molecule.     

Driving activity. A quantitative study.

A comparative study of driving activity between normal subjects and neurological patients was performed. Driving activity was considered as the energy of the visual evoked potentials filtered at the same frequency of stimulation (1, 2, 4, 7, 10, 12 and 15 cps) using a CAT 400 C computer as a digital filter. The hemispheric symmetry of the responses was measured by the Pearson product moment correlation coefficient and the signal energy ratio. Each symmetry measure for every patient was compared with the normal values and considered abnormal when differences were greater than 3 SD from the normal mean. Of 25 patients 14 of them with a normal EEG, 23 presented severe alterations in the symmetry of the filtered visual evoked responses. Each patient showed a peculiar pattern of abnormality. It is concluded that the procedure described is a very powerful method in the discrimination of brain lesions.     

Antiviral activity of benzimidazole derivatives. II. Antiviral activity of 2-phenylbenzimidazole derivatives

Seventy-six 2-phenylbenzimidazole derivatives were synthesized and evaluated in cell-based assays for cytotoxicity and antiviral activity against a panel of 10 RNA and DNA viruses. The most commonly affected viruses were, in decreasing order, CVB-2, BVDV, Sb-1, HSV-1, and YFV, while HIV-1 and VSV were not affected, and RSV, VV and Reo-1 were only susceptible to a few compounds. Thirty-nine compounds exhibited high activity (EC₅₀ = 0.1–10 μM) against at least one virus, and four of them were outstanding for their high and selective activity against VV (24, EC₅₀ = 0.1 μM) and BVDV (50, 51, and 53 with EC₅₀ = 1.5, 0.8, and 1.0 μM, respectively). The last compounds inhibited at low micromolar concentrations the NS5B RdRp of BVDV and also of HCV, the latter sharing structural similarity with the former. The considered compounds represent attractive leads for the development of antiviral agents against poxviruses, pestiviruses and even HCV, which are important human and veterinary pathogens.     

Bactericidal activity of peroxynitrite.

Peroxynitrite is a strong oxidant formed by macrophages and potentially by other cells that produce nitric oxide and superoxide. Peroxynitrite was highly bactericidal, killing Escherichia coli in direct proportion to its concentration with an LD50 of 250 microM at 37 degrees C in potassium phosphate, pH 7.4. The apparent bactericidal activity of a given concentration peroxynitrite at acidic pH was less than that at neutral and alkaline pH. However, after taking the rapid pH-dependent decomposition of peroxynitrite into account, the rate of the killing was not significantly different at pH 5 compared to pH 7.4. Metal chelators did not decrease peroxynitrite-mediated killing, indicating that exogenous transition metals were not required for toxicity. The hydroxyl radical scavengers mannitol, ethanol, and benzoate did not significantly affect toxicity while dimethyl sulfoxide enhanced peroxynitrite-mediated killing. Dimethyl sulfoxide is a more efficient hydroxyl radical scavenger than the other three scavengers and increased the formation of nitrogen dioxide from peroxynitrite. In the presence of 100 mM dimethyl sulfoxide, 60.0 +/- 0.3 microM nitrogen dioxide was formed from 250 microM peroxynitrite as compared to 2.0 +/- 0.1 microM in buffer alone. Thus, formation of nitrogen dioxide may have enhanced the toxicity of peroxynitrite decomposing in the presence of dimethyl sulfoxide.     

Antifungal activity of transferrin.

Inhibitory effects of transferrin on fungal growth were successfully estimated by measuring fungal ATP content. By this method, it was demonstrated that both human and rabbit transferrin possessed the inhibitory effect in the absence of any other factor on yeast-like and filamentous fungi. However, rabbit stimulation factor enhanced the inhibitory effect. The inhibitory effect of transferrin was nonspecific and correlated with unsaturated iron binding capacity (UIBC) of transferrin. Human transferrin was more inhibitory than rabbit transferrin.     

Enzymatic activity of aphroproteins.

Chitinase and proteinase activities were found in aphroproteins excreted by larvae of the cicada Aphrophora costalis Mats; this accounts for their fungicidal effect. Aphroproteins did not show DNase or RNase activities and did not exhibit properties of proteinase inhibitors. The data suggest that larval foam protects the larva and host plant from entomogenous and phytopathogenic fungi.     

Chaperone activity of DsbC.

DsbC, a periplasmic disulfide isomerase of Gram-negative bacteria, displays about 30% of the activities of eukaryotic protein disulfide isomerase (PDI) as isomerase and as thiol-protein oxidoreductase. However, DsbC shows more pronounced chaperone activity than does PDI in promoting the in vitro reactivation and suppressing aggregation of denatured D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) during refolding. Carboxymethylation of DsbC at Cys98 decreases its intrinsic fluorescence, deprives of its enzyme activities, but lowers only partly its chaperone activity in assisting GAPDH reactivation. Simultaneous presence of DsbC and PDI in the refolding buffer shows an additive effect on the reactivation of GAPDH. The assisted reactivation of GAPDH and the protein disulfide oxidoreductase activity of DsbC can both be inhibited by scrambled and S-carboxymethylated RNases, but not by shorter peptides, including synthetic 10- and 14-mer peptides and S-carboxymethylated insulin A chain. In contrast, all the three peptides and the two nonnative RNases inhibit PDI-assisted GAPDH reactivation and the reductase activity of PDI. DsbC assists refolding of denatured and reduced lysozyme to a higher level than does PDI in phosphate buffer and does not show anti-chaperone activity in HEPES buffer. Like PDI, DsbC is also a disulfide isomerase with chaperone activity but may recognize different folding intermediates as does PDI.     

Proteolytic activity of vitreous-humour.

It has been found that the bovine vitreous--humour did not digest in vitro collagen at physiological and acidic pH. A proteolytic activity against haemoglobin in acid pH was found both in bovine and human vitreous-humours. The activity of human vitreous-humour increased significantly in endophtalmitis and glaucoma. In all pathological conditions studied the pH optima were at more acidic values than in control.     

Adrenocortical activity during meditation.

We studied acute plasma cortisol and testosterone concentration changes during the practice known as "transcendental meditation" (TM) and during control rest. Three groups of normal, young adult volunteers were studied: a group of controls, these same controls restudied as practitioners after 3 to 4 months of TM practice, and a group of long-term, regular TM practitioners (3 to 5 years of practice). No change was found in controls during rest. Cortisol declined, but not significantly, in restudied controls, while cortisol decreased significantly in long-term practitioners during meditation and remained somewhat low afterward. No change in testerone concentration was noted during either rest or TM. Apparently, the practice of TM becomes associated with psychophysiologic response(s) which acutely inhibit pituitary-adrenal activity.