Separation and kinetic properties of the molecular forms of chicken liver cytoplasmic aspartate aminotransferase

A method is proposed for the separation of the five molecular forms, alpha, beta, gamma, delta and epsilon, of chicken liver cytoplasmic aspartate aminotransferase free from lactate dehydrogenase activity. These molecular forms varied in isoelectric point, but no differences were observed either in their Michaelis constants or in the degree of their inhibition by excess of 2-oxoglutarate or L-aspartate.     

The Stroop effect on Slovak-Hungarian bilinguists

We studied the processes of interference vs language automatisms in a group of Slovak-Hungarian bilinguists (N = 19, age 13 years) and compared their performance in the Stroop test with two control groups - Slovak (N = 24) and Hungarian (N = 31) monolinguists of the same age. - The Stroop effect, whose essence is an interfering effect of the meaning of the word on its physical characteristic - colour, proved to be a suitable method in the study of information processing in the semantic memory of bilinguists as well as in determining dominance of one language over the other. Slovak-Hungarian bilinguists showed, as a rule, shorter times in Hungarian and approximated in their performance Hungarian monolinguists. It can be assumed that reaction times in the Stroop test are conditioned not only by interference of the other language but also by language automatisms, whereby interference and speech automatisms are in an indirect correlation. - The results thus indicate that processes of interference and language automatisms cannot be separated. Dominance of one language structure over the other (Hungarian over Slovak) was confirmed not only in our experimental method but also in the subjective rating.     

Nodular fasciitis initially diagnosed by aspiration cytology

A case of nodular fasciitis diagnosed by fine needle aspiration cytology is described. The cytologic findings included fusiform cells, mitoses, macrophages, multinucleated giant cells and mesenchymal elements in a characteristic granular background substance. The cytopathologic diagnosis was subsequently confirmed by the histopathologic study of the tumor and by electron microscopy.     

Maximal exercise capacity in adolescent European and Amerindian high-altitude natives

Forty-seven highland natives were given maximal exercise tests on a treadmill ergometer at 3,600 m. The subjects were grouped into four subsamples on the basis of ethnicity (European vs. Aymara) and age (young vs. old adolescent). Two-way ANOVA indicated that VO2max adjusted for body size did not differ significantly between ethnic groups but was significantly larger in older than younger boys within each ethnic group (p less than .05). This finding does not support the hypothesis that Amerindian highland natives have adapted genetically to hypoxia but is consistent with the hypothesis that the relatively high VO2max's of highlanders are acquired by developmental adaptation. Several measures of ventilation and oxygen transport capacity differed significantly between ethnic groups, suggesting that growing European and Aymara boys may respond somewhat differently to the stress of high-altitude hypoxia. However, despite these differences, VO2max, an integrated measure of the overall functional capacity of the oxygen transport system, did not differ significantly between ethnic groups, suggesting that both groups are equally capable of meeting the body's oxygen requirements during maximal exercise at high altitude.     

19q distal trisomy due to a de novo (19;22)(q13.2;p11) translocation

A 2 4/12-year-old girl whith a de novo 46,XX,-22 + der(22), t(19;22)(q13.2;p11) karyotype is described. From this and other eight similar cases previously published, a typical phenotype in distal 19q trisomy is concluded.     

Macrocyclic trichothecene toxins produced by Stachybotrys atra strains isolated in Middle Europe.

A total of 17 strains of Stachybotrys atra isolated in Hungary and Czechoslovakia were cultured on Sabouraud agar, and the toxins produced by them were chemically analyzed by gas-liquid chromatography, high-pressure liquid chromatography, and mass spectroscopy. Furthermore, brine shrimp (Artemia salina) bioassay was used for the determination of toxicity of the compounds examined. Macrocyclic trichothecenes (satratoxins H and G, roridin E, and verrucarin J as well as two other unidentified macrocyclic trichothecenes) were found in all of the cultures tested. The identities of satratoxins H and G, roridin E, and verrucarin J were qualitatively determined by high-pressure liquid chromatography and gas-liquid chromatography. The ratio of satratoxins H and G and roridin E was found to be similar in each of the strains tested, but the amount of verrucarin J found was different in each of them. One of the unidentified macrocyclic trichothecenes was equivalent to the compound isolated by Harrach et al. (Harrach et al., Appl. Environ. Microbiol. 41:1428-1433, 1981). The other one proved to be a newly isolated macrocyclic trichothecene toxin. Stachybotryotoxicosis, one of the oldest mycotoxicoses known, and a serious problem in Middle Europe (Gy. Danko, Magy. Allatorv. Lapja 31:226-232, 1976), is believed to be caused by macrocyclic trichothecene toxins produced by Stachybotrys atra (R. M. Eppley, in Rodricks et al., ed., Mycotoxins in Human and Animal Health, p. 285-293, 1977). Forty years ago, the death of animals in the Soviet Union was associated with this fungus (C. U. Ruhliada, in Proceedings of the All-Union Sci. and Tech. Conf., p. 47-51, 1980).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of glutathione depletion on gluconeogenesis in isolated hepatocytes

Glutathione-depleted hepatocytes, by incubation with diethylmaleate (DEM) or phorone (2,6-dimethyl-2,5-heptadiene-4-one), i.e., substrates of the GSH S-transferases (EC 2.5.1.18), showed rates of gluconeogenesis from various precursors significantly lower than controls; however the rate of glucose synthesis from fructose was similar to that of controls. Isolated hepatocytes from rats pretreated with those substrates 1 h before isolation to deplete hepatic glutathione (GSH) also showed a decrease of the rate of gluconeogenesis from lactate plus pyruvate. Incubation of hepatocytes with L-buthionine sulfoximine, a specific inhibitor of gamma-glutamyl-cysteine synthetase (EC 6.3.2.2), resulted in a decreased rate of gluconeogenesis from lactate plus pyruvate only when GSH values were lower than 1 mumol/g cells. Freeze-clamped livers from GSH-depleted rats showed a higher concentration of malate and glycerol 3-phosphate, indicating that GSH depletion probably affects phosphoenolpyruvate carboxykinase and glycerol-3-phosphate dehydrogenase activities. Several indicators of cell viability, such as lactate dehydrogenase leakage, malondialdehyde accumulation, ATP concentration, or urea synthesis from different precursors, were not affected by GSH depletion under the experimental conditions used here. Besides, the GSH/GSSG ratio remained unchanged in all cases.     

Possible mechanism of the allosteric activation of cAMP receptor protein

Secondary structure of cAMP receptor protein of E. coli was predicted and compared to its crystal structure in the complex with cAMP solved by McKay and Steitz. The two conformations coincide in the DNA binding domain but strikingly differ in the other domain which binds cAMP and causes protein dimerization. The comparison indicates that cAMP destabilizes a very long helix instead of which sheets are formed creating a hydrophobic pocket where cAMP binds. Consequently, the helix-sheets isomerization and a resulting change in the relative monomer disposition in the dimer appears to be the origin of cAMP-induced allosteric activation of the protein. Extremely long helices were also predicted in the regions of the regulatory subunit of cAMP-dependent protein kinase from bovine cardiac muscle where cAMP binds. It is thus likely that the proposed mechanism of the effect of cAMP on protein structure has wider implications.     

Binding of HMG14 non-histone protein to histones H2A, H2B, H1 and DNA in reconstituted chromatin

The interaction between calf thymus HMG14 and rat liver chromatin components has been studied via reconstitution and chemical cross-linking. Selective labeling of HMG14 with photoactivable reversible heterobifunctional reagents has allowed a clear identification of the histones interacting with it (histones H2A, H2B and H1). These results are not dependent on whether the chromatin samples used were bulk chromatin, mononucleosomes, or core particles (for H2A and H2B). In addition to histone proteins, DNA also seems to be involved in HMG14 attachment to nucleosome.     

Equilibrium of conformers in solution: spin-labelled angiotensin

The number of structural parameters were determined for spin-labelled angiotensin in aqueous solution with the use of fluorescence spectroscopy and 1H NMR relaxation induced by the spin label. At the same time all measured parameters were estimated theoretically by means of energy calculations and Monte-Carlo techniques. The matching procedure for experimental and computational data allows one to suggest a dynamic equilibrium between conformers of the molecule in aqueous solution and to estimate the values of their weights.