O-acetylated peptidoglycan: its occurrence, pathobiological significance, and biosynthesis.

Bacterial cell walls and their structural units, particularly peptidoglycan, induce a vast variety of biological effects in host organisms. The pathobiological effects of peptidoglycan are greatly enhanced by various modifications and substitutions to its basic composition and structure. One such modification is the presence of acetyl moieties at the C-6 hydroxyl group of N-acetylmuramyl residues, and to date, 11 species of eubacteria, including some important human pathogens, such as Neisseria gonorrhoeae, Proteus mirabilis, and Staphylococcus aureus, are known to possess O-acetylated peptidoglycan. This review addresses the influence of O-acetylation of peptidoglycan on its resistance to degradation both in vitro and in vivo, the clinical importance of the modification, and the currently held views on the pathway for its biosynthesis.     

Effects of dietary fat on cholesterol movement between tissues in CBA/J and C57BR/cdJ mice.

Differences in dietary fats cause differences in cholesterol metabolism in mice. CBA/J mice are resistant to diet-induced hypercholesterolemia and atherosclerosis; they adjust hepatic hydroxymethyl-glutaryl-CoA reductase activity (HMGR) to maintain homeostasis; C57BR/cdJ mice are susceptible, but young animals are thought to maintain homeostasis by changing fecal excretion of sterols. Compartmental modelling of movement of [4-14C]cholesterol was used to analyze movement of cholesterol between serum and liver, heart, and carcass in mice fed 40 en% fat, polyunsaturated to saturated fatty acid ratio (P/S) = 0.24 (US74) or 30 en% fat, P/S = 1 (MOD). Dietary effects were quite pronounced, while strain effects were more subdued. The C57/cdJ animals appear to regulate the overall cholesterol balance by reducing synthesis, as do the CBA/J animals, even though synthesis is not reduced to the same degree as in the CBA/J animals. Both diet and strain influence the whole-animal turnover rate, with slower turnover occurring for C57BR/cdJ animals and animals fed the US74 diet.     

Interaction between Mitochondrial Cytochromes and Linoleic Acid Hydroperoxide: POSSIBLE CONFUSION WITH LIPOXYGENASE AND ALTERNATIVE PATHWAY

O₂ uptake by tissue extracts in the presence of linoleic acid is generally ascribed to lipoxygenase. Such an O₂ uptake can be observed not only with mitochondria of Solanum tuberosum L. and Arum maculatum L. and pure lipoxygenase but also with cytochrome c. However, the rate of oxidation is highly dependent on the procedure used to prepare the solutions of linoleic acid. Unless special care is taken to prevent contact between linoleic acid and O₂, it appears that linoleic acid hydroperoxide is readily formed. This derivative can be readily oxidized by mitochondria or cytochrome c. On the other hand, the use of a rapid and specific enzymic procedure to estimate the disappearance of linoleic acid demonstrates that linoleic acid itself is not consumed at any appreciable rate by mitochondria or cytochrome c, the true substrate being linoleic acid hydroperoxide. During the reaction, the heme nucleus of added cytochrome c or of mitochondrial cytochromes undergoes deep alterations. Therefore, caution should be exerted when equating an O₂ uptake observed in the presence of linoleic acid to a lipoxygenase activity. The same holds true for the similarity of reaction towards specific inhibitors between lipoxygenase and the cyanide-insensitive pathway oxidase.     

Age-related changes in central nervous system enkephalins and substance P

Concentrations of substance P and met- and leu-enkephalins were measured by radioimmunoassay in discrete rat brain nuclei of young (4–5 months) and old (24–26 months) rats. The substance P content of n. anterior (hypothalami), n. ventromedialis, n. premamillaris ventralis, n. interstitialis striae terminalis, n. entopeduncularis and n. dorsalis raphes is reduced in old rats. The met-enkephalin content is decreased in n. suprachiasmaticus, n. arcuatus and n. premamillaris ventralis while the leu-enkephalin content of n. preopticus medialis, n. suprachiasmaticus, n. paraventricularis, n. ventromedialis and n. premamillaris ventralis is decreased in old rats.     

Characterization of a partially purified adenosine triphosphatase from a corn root plasma membrane fraction

The (K⁺,Mg²⁺)-ATPase was partially purified from a plasma membrane fraction from corn roots (WF9 × Mol7) and stored in liquid N₂ without loss of activity. Specific activity was increased 4-fold over that of the plasma membrane fraction. ATPase activity resembled that of the plasma membrane fraction with certain alterations in cation sensitivity. The enzyme required a divalent cation for activity (Co²⁺ > Mg²⁺ > Mn²⁺ > Zn²⁺ > Ca²⁺) when assayed at 3 millimolar ATP and 3 millimolar divalent cation at pH 6.3. When assayed in the presence of 3 millimolar Mg²⁺, the enzyme was further activated by monovalent cations (K⁺, NH₄⁺, Rb⁺ Na⁺, Cs⁺, Li⁺). The pH optima were 6.5 and 6.3 in the absence and presence of 50 millimolar KCl, respectively. The enzyme showed simple Michaelis-Menten kinetics for the substrate ATP-Mg, with a K_m of 1.3 millimolar in the absence and 0.7 millimolar in the presence of 50 millimolar KCl. Stimulation by K⁺ approached simple Michaelis-Menten kinetics, with a K_m of approximately 4 millimolar KCl. ATPase activity was inhibited by sodium orthovanadate. Half-maximal inhibition was at 150 and 35 micromolar in the absence and presence of 50 millimolar KCl. The enzyme required the substrate ATP. The rate of hydrolysis of other substrates, except UDP, IDP, and GDP, was less than 20% of ATP hydrolysis. Nucleoside diphosphatase activity was less than 30% of ATPase activity, was not inhibited by vanadate, was not stimulated by K⁺, and preferred Mn²⁺ to Mg²⁺. The results demonstrate that the (K⁺,Mg²⁺)-ATPase can be clearly distinguished from nonspecific phosphohydrolase and nucleoside diphosphatase activities of plasma membrane fractions prepared from corn roots.     

Radioimmunoassay of prostaglandins E1, E2, and F2α in unextracted plasma, serum and myocardium

A radioimmunoassay procedure for the determination of PGE₁, PGE₂, and PGF₂α is presented. The procedure involves the pre-precipitation of each prostaglandin specific antiserum with the precipitating antisera (ARGG), and the use of these antisera mixtures in assaying for PGE₁, PGE₂, and PGF₂α. Applicability of the methods to unextracted plasma, serum and myocardial homogenate has been demonstrated through tests of specificity, recovery, reproducability and parallelism. A mathematical correction for cross-reactivity between PGE₁ and PGE₂, and their opposing antisera is given. To demonstrate the utility of the methodology in differentiation of experimental variables, prostaglandin concentrations in unincubated serum, incubated serum, and the rate of prostaglandin production in serum of dogs are given.     

Leukocyte migration inhibitory factor (LMIF) production in unidirectional mixed lymphocyte cultures.

Puromycin treatment of lymphocytes was used to develop a one-way test for leukocyte migration inhibitory factor (LMIF) production in the mixed lymphocyte culture (MLC) reaction. Lymphocytes incubated with this protein synthesis inhibitor induced a vigorous mediator production by nontreated allogeneic cells, being themselves unable to respond to stimulator cells. When puromycin-treated cells were stimulated with the mitogens PHA, ConA, or PWM, overall protein and DNA synthesis were significantly decreased with concomitant abolishment of LMIF production. Viability of stimulator lymphocytes was found to be essential for generation of the mediator in MLC reaction.     

Circadian variations of the effects of ethanol and of blood ethanol values in the healthy adult man. Chronopharmacological study]

Six healthy young men (22 to 26 years) who had fasted for 12 hours volunteered for this study (subject synchronization: diurnal activity from 07(00) to midnight and nocturnal rest). A set dose of ethanol (0.67 g/kg body weight) was ingested at the fixed (and random) hours of 07(00), 11(00), 19(00) and 23(00), with a week between tests. A set of physiological variables: psychological tests (selft-rating of mood, of physical vigor and of ebriety, tempo, random number addition test); physical variables (heart rate, systolic and diastolic blood pressure, peak expiratory flow, oral temperature and grip strength); blood variables (plasma ethanol, cortisol, lactic acid, pyruvic acid, glucose and erythrocyte K+) and urinary variables (volume, epinephrine, nor-epinephrine and 5-HIAA) were documented at least at 4 hourly intervals and set times. The cosinor method was used for chronobiological statistical analyses. The parameters characterizing the ethanol pharmacokinetics (chronopharmacokinetics) demonstrated a circadian rhythm (p less than 0.05): e. g. the peak height of ethanolemia is greater when ethanol is ingested at 07(00) than at other times. Also a circadian rhythm in biosystems susceptibility can be demonstrated (p less than 0.05) (chronesthesy) with a peak time not necessarily corresponding either to that of ethanolemia or to that of other variables. The overall circadian changes in ethanol effects (chronergy) can be viewed as a combination of both ethanol chronesthesy and chronokinetics.     

Sex in Penicillium: Combined phylogenetic and experimental approaches

We studied the mode of reproduction and its evolution in the fungal subgenus Penicillium Biverticillium using phylogenetic and experimental approaches. We sequenced mating type (MAT) genes and nuclear DNA fragments in sexual and putatively asexual species. Examination of the concordance between individual trees supported the recognition of the morphological species. MAT genes were detected in two putatively asexual species and were found to evolve mostly under purifying selection, although high substitution rates were detected at some sites in some clades. The first steps of sexual reproduction could be induced under controlled conditions in one of the two species, although no mature cleistothecia were produced. Altogether, these findings suggest that the asexual Penicillium species may have lost sex only very recently and/or that the MAT genes are involved in other functions. An ancestral state reconstruction analysis indicated several events of putative sex loss in the genus. Alternatively, it is possible that the supposedly asexual Penicillium species may have retained a cryptic sexual stage.     

Expression of chemerin and its receptors in the ovaries of prepubertal and mature gilts

Recent studies have demonstrated that chemerin participates in the regulation of female reproductive function at the level of the ovaries. Due to the lack of data concerning the presence of the chemerin system (chemerin and its receptors: CMKLR1, GPR1, CCRL2) in the ovaries of pigs, one of the most economically important livestock species, the aim of this study was to investigate the expression and localization of chemerin and its receptors in the ovaries of prepubertal and mature gilts. We also aimed to examine the concentrations of chemerin in the follicular fluid of prepubertal and mature animals. In the present study, we have demonstrated the expression patterns of chemerin system components in the porcine follicles of different sizes of prepubertal and mature animals, as well as in corpora lutea of mature gilts during the estrous cycle and early pregnancy. The obtained results suggest that the expression of chemerin system components is influenced by the reproductive stage, cell type, and the hormonal status of gilts (the estrous cycle/pregnancy). We have also presented the localization of the chemerin system components in various ovarian structures, and also showed changes in the concentration of chemerin in the follicular fluid of pigs. The presented findings not only confirm that chemerin is produced locally in the porcine ovary but they also demonstrate that chemerin directly affects ovarian cells, as confirmed by the presence of chemerin receptors in all ovarian structures. Therefore, chemerin appears to be an important intra‐ovarian factor that could regulate ovary function in pigs.