Degradation of benzenesulfonate to sulfite in bacterial extract.

Sulfite formation from benzenesulfonate was studied in extracts from a bacterium grown on this compound as a main carbon source. The activity of sulfite formation depended on the presence of NADH and oxygen as well as magnesium, suggesting an oxygenation-type reaction. The activity was found in a fraction precipitated by ammonium sulfate at 35-50% saturation; the specific activity was 15 times higher than that of crude extract, probably due to the elimination of inhibitory substances of low molecular weight from the preparation. In a distillate of the reaction mixture, phenol was found. Pyrocatechol as well as benzenesulfonate was oxidized in the crude extract, but phenol was not.     

The role of phosphoric acid residues in the formation of antigenic determinants of the structural components of DNA

The inhibitory activity of thymidine, thymidine triphosphate and thymidyl oligonucleotides was studied in thymidine-antithymidine antibodies reaction. Thymidine was shown to have the greatest inhibitory effect, with thymidine triphosphate and thymidyl oligonucleotide inhibitory activity less expressed and reducing with the increase in oligonucleotide length. The effect of thymidine, thymidine triphosphate and thymidyl oligonucleotides on the interaction of antisera and SLE patients' sera with denatured DNA was studied. It was shown that thymidine triphosphate and particularly thymidyl oligonucleotides are characterized by greater inhibitory capacity, as compared to thymidine. It was found that only thymine dimers bound by phosphate groups can inhibit the interaction of UV-irradiated DNA with antiserum specific for UV-modified DNA. The data obtained suggest that the charge determined by phosphoric acid residues plays an essential role in the interaction of antibodies induced to charged structural DNA components.     

Protective effects of luteolin-7-O-β-D-glucuronide methyl ester from the ethyl acetate fraction of Lycopi Herba against pro-oxidant reactive species and low-density lipoprotein peroxidation

In this study the potent scavenging activity of “Lycopi Herba” (LH) extract was studied using the following: evaluation of the total phenolics, measuring the antioxidant activity by Trolox equivalent antioxidant concentration, measuring the scavenging effects on reactive oxygen species, on reactive nitrogen species, and measuring the inhibitory effect on Cu²⁺ induced human low-density lipoprotein oxidation in vitro. The ethyl acetate fraction from the LH extracts were found to have a potent scavenging activity against all of the reactive species tested, as well as an inhibitory effect on LDL oxidation. Therefore, we isolated and identified luteolin-7-O-β-D-glucuronide methyl ester as the major compound from the ethyl acetate fraction of LH and their antioxidant activities were evaluated.     

Morphine-like activity of the enkephalin analog Tyr-D-Ala-Gly-Phe-NH2

The analgetic activity of the tetrapeptide enkephalin analog, its influence on the interneuronal transmission of excitation in various areas of the central nervous system and on opiate receptors of vas deferens were studied. The tetrapeptide was found to have a marked analgetic effect during intravenous injection to mice but to be less active than morphine. The tetrapeptide as well as morphine inhibited the impulse summation in rabbits and both spontaneous and bradykinin-induced neuronal activity in the rat sensory motor cortex. The tetrapeptide inhibited the contractions of isolated vas deferens in mice. The opiate antagonist naloxone eliminated both analgetic effect of the tetrapeptide and its inhibitory effect on the impulse summation, neuronal activity and contractions of vas deferens.     

Inhibition of antibody-dependent cell-mediated cytotoxicity (ADCC) by antiserum raised against brain tissue

Treatment of mouse spleen cells with a rabbit anti-mouse brain (RAMB) antiserum markedly suppressed antibody-dependent cell-mediated cytotoxicity (ADCC) on trinitrophenyl-coupled sheep erythrocyte targets. This inhibitory activity of RAMB antiserum was complement independent, absorbable with mouse brain tissue, and appeared to be separable from the anti-Thy-1 activity of this serum. Absorption studies indicated that various T- and B-lymphocyte cell lines as well as macrophage-like cell lines are not able to absorb the inhibitory activity of RAMB antiserum. In contrast, thymocytes and spleen cells, as well as the neural cell line, PC12, a chromocytoma derived from rat adrenal medulla, were capable of absorbing the inhibitory activity to some extent, suggesting that antigens characteristic for ADCC effector cells can be found on these cell populations.     

Morphology and antibacterial activity of carbohydrate-stabilized silver nanoparticles

Silver nanoparticles were prepared by a simple hydrothermal route and chemical reduction using carbohydrates (sucrose, soluble and waxy corn starch) as reducing as well as stabilizing agents. The crystallite size of these nanoparticles was evaluated from X-ray diffraction (XRD) and transmission electron microscopy (TEM) and was found to be 25 nm. The effect of carbohydrates on the morphology of the silver nanocomposites was studied using scanning EM (SEM). The nanocomposites exhibited interesting inhibitory as well as bactericidal activity against both Gram positive and Gram negative bacteria. Incorporation of silver also increased the thermal stability of the carbohydrates.     

Inhibitory deficit in schizophrenia is not necessarily a GABAergic deficit

1. Current evidence strongly supports the idea of an inhibitory deficit as a central pathophysiological mechanism in schizophrenia. This deficit has been well documented in sensory gating and paired-pulse studies and may be related to decreases in inhibitory interneurons found in schizophrenic patients.2. The GABAergic system has been repeatedly postulated to mediate this deficit, but the findings are controversial, at least in some areas, and mostly negative regarding treatment with drugs enhancing GABAergic activity. Therefore, the scope of mediators of this inhibitory deficit should be widened and the neuromodulator adenosine is proposed as a candidate to be further studied.3. A state of adenosinergic hypoactivity in schizophrenia is compatible not only with the inhibitory deficit but also with symptoms, clinical response to antipsychotics, impaired sensory gating, deteriorating course, increased smoking, and sleep alterations reported in schizophrenia.4. It is concluded that although the GABAergic system should be further studied, especially in sensory gating model in humans, emphasis on other inhibitory mechanisms may prove useful and provide more effective treatment.     

The antihypertensive drug carvedilol inhibits the activity of mitochondrial NADH-ubiquinone oxidoreductase

A study is presented on the interaction of carvedilol with mitochondria isolated from several rat organs. It is shown that carvedilol causes a moderate uncoupling effect under non phosphorylating succinate supported respiration of intact mitochondria, as well as a marked inhibition of coupled respiration with NAD-dependent substrates. The inhibitory effect was also found in the bovine heart purified Complex I as well as in experiments with mitochondrial particles, where the individual redox segments of the respiratory chain were analysed. It is also shown that carvedilol, though exhibiting an intrinsic scavenger activity, caused reactive oxygen species to be produced as a consequence of its inhibitory effect on the steady-state respiration. Under these conditions the pro-oxidant activity of carvedilol appears to prevail over its scavenging activity, and a net generation of ROS is promoted.     

Behavioural effects of luteinizing hormone-releasing hormone (LHRH) in rats.

Behavioural effects of intracerebroventricularly-injected (icv) LHRH were studied in female rats. Locomotor and exploratory activities as well as irritability were determined. A pronounced inhibitory effect of 10 micrograms doses of LHRH was found. At 100 micrograms doses of LHRH, barrel behaviour was observed. We conclude that LHRH can modify the activity of central serotonergic receptors in rats.     

The role of various parts of the amygdaloid complex in the regulation of activity of respiratory neurons]

In microelectrophysiological investigations influences of different nuclear regions of the amygdaloid complex on the spike activity of the functionally identified single respiratory neurons of the medulla oblongata were studied in anesthetized cats. It was established a qualitative different character of the changes of unit activity of the medullary respiratory neurons in case of stimulation of phylogenetically old corticomedial or new basolateral nuclear groups of the amygdala. It was shown higher reactivity of the investigated neurons to stimulation of the corticomedial nuclei than basolateral. The influences of the corticomedial nuclear groups on the bulbar inspiratory and expiratory neurons were facilitatory as well as inhibitory with prevailing excitatory effects. It was found that influences of the phylogenetically new neoamygdaloid structures of basolateral region on spike activity of the bulbar respiratory neurons differ accordingly to their topographical differentiation. Mechanisms of amygdaloid control of activity of the medullary respiratory neurons are discussed.     

MEA-based recording of neuronal activity in vitro

Based on the advantages of MEA-based recording, developmental changes of spontaneous activity and tetanus-induced modification of evoked activity were studied. Rat cortical neurons were cultured on MEAs and the spontaneous activity was continuously monitored for two months. The activity started a few days after plating. During the second week, the cultures generated periodic synchronized bursts, which were the characteristic properties of cortical neurons in vitro. In about one month, the cultured networks reached a steady state. Between these two, we found a critical period during which only weak activities were generated. This critical period might reflect the transition from immature networks to mature networks including precisely controlled excitatory and inhibitory synapses. We could elicit clear evoked responses with high reproducibility in mature cultures. A focal tetanic stimulation was applied to the mature cultures and how the tetanus affects 64 kinds of evoked activity was studied. The evoked responses showed bi-directional changes in their propagation patterns, potentiation and depression. These induced changes reflected the correlation properties with the tetanized activity pattern. The next step will be the combination of long-term recording and multi-site stimulation. How long does the induced change last, as well as how additional strong activity affects the previously induced changes, will be studied.     

Analogs of RGDVY and GRGD peptides inhibit Mycobacterium kansasii phagocytosis

Continuing our research on Mycobacteria kansasii phagocytosis inhibition, we have examined in that context three series of peptides derived from the RGDVY and GRGD sequences. It was found that the levels of the inhibitory activity depend on the amino acid composition as well as on the particular peptide sequence. Distinct inhibitory activity was found in the case of thymopentin (RKDVY), the active fragment of thymopoietin. In this case the Mycobacterium phagocytosis inhibition should be combined with general immunostimulatory activity of RKDVY peptide. Our examination of a series of GRGDV analogs with a successively prolonged oligo-Gly linker inserted into the peptide chain showed that the distance between the Arg and Asp residues required for such an activity should be about 9A.     

Neural control of heartbeat during two antagonistic behaviors: whole body withdrawal and escape swimming in the Mollusk <Emphasis Type="Italic">Clione limacina</Emphasis>

Two cardioexcitatory and one cardioinhibitory neural groups have been previously identified as the central cardioregulatory system in the pteropod mollusk Clione limacina. We describe in this study one additional element of the central cardioregulatory system, which consists of a large intestinal neuron named Z-cell with a novel effect on the heart activity. Intracellular stimulation of the Z-cell induced only auricle contractions with no effect on the ventricle activity. The Z-cell processes were traced down to the heart, and vigorous branching was found in the auricle tissue. Specific patterns of activity of the Z-cell as well as intestinal heart excitatory and inhibitory neurons were studied during initiation of two behaviors-whole body withdrawal and escape swimming. It was found that initiation of both behaviors was accompanied by activation of Z-cell and intestinal heart excitor neurons. The firing rate of neurons induced by sensory stimuli was sufficient to trigger auricle contractions in the semi-intact preparations. Video analysis of heart activity revealed that auricle indeed was activated during both active and passive avoidance reactions, though the intensity and delay of the activation were different. The possible physiological role of the auricle contractions during antagonistic forms of behavior is discussed.     

Possible mechanisms of amygdala participation in the regulation of gastric motor activity

Mechanisms of the amygdala central nucleus (CNA) influence on gastric motor reflex activity were studied in electrophysiological and neuroanatomical experiments in Wistar rats. In the anaesthetized animals, electrical stimulation of the CNA affected spontaneous gastric motility and caused inhibitory as well as excitatory changes of vagus-induced gastric relaxation. The most significant and mainly inhibitory effects were observed under the stimulation of the medial CNA. Microinjection of the anterograde tracer Phaseolus vulgaris-leucoagglutimn (PHA-L) into the different divisions of the CNA revealed direct projections from its dorso-medial portion to the gastric related area of the dorsal vagal complex. Electrical stimulation of this amygdaloid area was found to change activity of the bulbar gastric related neurons. Inhibitory and excitatory changes of their vagus-induced responses under the amigdala stimulation were manifested as a general modulation of all phases of the reaction or a selective modulation of some of them. These mechanisms may underlie the amygdalo-fugal modulation of gastric motor reflex activity.     

Separation of the gonadotropic activity of crude choriogonadotropin from the inhibitory effect on lymphocyte transformation.

The effect of choriogonadotropin of different purities on the transformation of peripheral human lymphocytes was studied. Various crude hormone batches inhibited lymphocyte transformation in a dose-dependent manner, both in the mixed lymphocyte reaction and in the phytohemagglutinin-induced stimulation. The inhibitory activity, however, was found not to be correlated with the gonadotropic activity of the crude hormone batches (2660-4300 IU/mg). Choriogonadotropin (13 000 IU/mg), which was purified in 3 steps, showed no inhibitory effect except at high doses (greater than 5000 IU/ml final dilution). More detailed investigations provided evidence that in the first step of the choriogonadotropin purification procedure (batch adsorption of crude choriogonadotropin on SP-Sephadex C-50), the inhibitory activity can be enriched in a fraction (Fract. I) which displays a very low gonadotropic activity (less than 500 IU/mg). A further separation of Fract. I was achieved by isoelectric focusing as well as by chromatography on DEAE-Sephadex A-25. By these means, the inhibitory potency could be enriched more than 100-fold. The substances which display inhibition of DNA synthesis in lymphocytes were proven to act in a nontoxic way. A preliminary characterization of the strongly inhibiting substances which show a dose-dependent suppression of lymphocyte transformation by about 99%, showed that this effect is probably exerted via non-dialysable sialoglycoproteins. By a fourth purification step entailing a chromatography of purified choriogonadotropin (13 000 IU/mg) on SP-Sephadex C-50, a highly purified choriogonadotropin (14000 IU/mg) could be obtained which showed no inhibitory effect on lymphocyte transformation (in both mixed lymphocyte reaction and in phytohemagglutinin-induced stimulation) up to a dose of 43 000 IU/ml. The components which were removed from choriogonadotropin in this step seem to be immunologically identical with the strongly inhibiting substances isolated by isoelectric focusing. These investigations demonstrate that biologically active, highly purified choriogonadotropin is unable to inhibit lymphocyte transformation. The inhibitory activity of crude hormone can be enriched in choriogonadotropin-free fractions. Therefore, it is concluded that the inhibitory activity of crude hormone is not a property of choriogonadotropin itself.     

The relationship between ACE inhibitory activity and degradations of sulfur containing materials in Dolsan leaf mustard juice

This study was carried out to investigate the relationship ACE inhibitory activity and degradations of sulfur containing materials in Dolsan leaf mustard juice (DLMJ). The changes of sulfur containing materials which were treated with autolysis, myrosinase, ascorbate and papain were studied, as well as the changes of ACE inhibitory activity in DLMJ. At 37°C, sulfur containing materials by autolysis decreased most rapidly from 0.43% to 0.13% in the second day. Conversely, ACE inhibitory activity increased most from 66% to 87%, in the second day at 37°C. As myrosinase concentrations increased more, sulfur containing materials in DLMJ decreased more. The ACE inhibitory activities at 0, 0.5, 1, 2, and 4 Units of myrosinase for 240 min later were 70, 74, 75, 82, and 85%, respectively. At 1 mM ascorbate, concentrations of sulfur containing materials in DLMJ decreased more significantly on the second day than on the other days. At 1 mM ascorbate for 6 days, ACE inhibitory activity reached a maximum of about 92%. And, an increase of papain concentration was noted in accordance with a decreased sulfur containing materials. The maximum rate of ACE inhibitory activity at control, 3, 6, and 12 Units of papains treatments was shown as 70, 70, 75, and 78% at 60 min, respectively. These results suggested that the degradation of sulfur containing materials led to the increase of ACE inhibitory activity. Consequently, it was suggested that ACE inhibiting was significantly related to the degradatives of sulfur containing materials.     

Inhibition of delta-aminolevulinic acid dehydratase in human red blood cells by lead and activation by zinc or cysteine.

Inhibition of blood delta-aminolevulinic acid dehydratase(ALA-D) activity by lead was studied in vivo and in vitro. In vivo, a negative linear correlation (r = -0.85) was found between the logarithmic values of ALA-D activity and blood lead levels. In vitro the inhibitory effect of lead on blood ALA-D activity increased both with contact time and contact temperature of lead with blood before ALA-D assay. Maximum enzyme inhibition occurred after 14 h of contact at 25 degrees C. Inhibition of ALA-D activity by lead, in vivo as well as in vitro, is suppressed by the addition of zinc or cysteine. The logarithmic values of the activity ratios increase linearly with blood lead concentrations. The increase in ALA-D activity brought about by the addition of zinc or cysteine can be used to identify cases of low enzyme activity with no lead intoxication involved. The same technique can also detect cases in which ALA-D inhibition may be concealed by a presumably high initial enzyme activity as observed in some patients.     

Feedback regulation of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthetase from a marine bacterium, Vibrio MB22

A marine bacterium, Vibrio MB22, has been studied to determine the pattern of feedback regulation of the first enzyme unique to the biosynthesis of the aromatic amino acids, 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthetase. The crude extract was used to study response of the enzyme to various salts as well as possible feedback inhibitors. Ethylenediaminetetraacetic acid was found to be inhibitory to enzyme activity, and only CoCl(2), of the salts tested, allowed full recovery as well as apparent stimulation of the DAHP synthetase activity. The DAHP synthetase activity was inhibited solely by the aromatic amino acids, tyrosine, tryptophan, and phenylalanine, of the possible effectors tested. Further work demonstrated the existence of three isozymes of DAHP synthetase, each primarily inhibited by one of the aromatic amino acids.     

Inhibitors of liver lysosomal acid phospholipase A1

Lysosomal acid phospholipase A1, as well as other lysosomal enzymes, may be released under pathophysiological conditions into extralysosomal compartments. As shown here, several unspecific mechanisms exist which inhibit the hydrolysis of membrane diacylphospholipids by lysosomal acid phospholipase A1 and hence prevent an uncontrolled membrane destruction. These findings were obtained by employing partially purified rat liver lysosomal acid phospholipase A1 and sonicated radioactively labeled phosphatidylethanolamine or phosphatidylcholine as substrate. The inhibitory principles found include (1) pH, (2) inorganic cations, and (3) various proteins. Inorganic cations and proteins, however, inhibited lysosomal acid phospholipase A1 activity only below pH 6.0, and inhibition never exceeded 96%. Of the inorganic cations studied, the divalent species, as compared to the monovalent one, impaired lysosomal acid phospholipase A1 activity at significantly lower concentrations. Virtually all of the intracellular and extracellular proteins studied inhibited the enzyme activity, but the inhibitory potencies of the different proteins varied considerably. In general, basic and hydrophobic proteins were the most potent inhibitors, whereas glycoproteins appeared to be less inhibitory. The degree of inhibition of the enzyme activity in both proteins and inorganic cations depended on the substrate concentration and not on that of the enzyme. Binding studies provided evidence for inhibitor-substrate and against inhibitor-enzyme interactions.     

Biochemical evidence for the role of alkyl-lysophospholipids on liver sialyltransferase

Antineoplastic alkyl-lysophospholipids were found to exert a strong inhibitory effect on membranous or solubilized asialomucin-sialyltransferase (CMP-N-acetylneuraminate: D-galactosyl-glycoprotein N-acetylneuraminyltransferase, EC 2.4.99.1) activity. This inhibitory effect was dependent on the presence of the choline moiety in position 3 of the glycerol molecule, as well as on the presence of long ether-linked aliphatic side chain in position 1 and the absence of any large substituent in position 2. As an example, 1-octadecyl-2-O-methyl-glycero-3-phosphorylcholine acted as a mixed-type inhibitor. Such an inhibitory process on sialyltransferase activity might be an additional factor in the tumor cell destructive effect of alkyl-lysophospholipids.