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Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Islet-activating protein (IAP), pertussis toxin, is a hexameric protein composed of an A protomer and a B oligomer, the residual pentamer having such a subunit assembly that two different dimers, dimer 1 and dimer 2, are connected with each other by means of the smallest C subunit. Incubation of IAP with formaldehyde and pyridine-borane produced the modified toxin in which most of the free amino groups were dimethylated. The methylated and nonmethylated (native) IAP were disintegrated into their respective constituent components, which were then cross combined to reconstitute hybrid toxins with the original hexameric structure. The binding of the B oligomer to the mammalian cell surface via dimer 2 was, but the binding via dimer 1 was not, seriously impaired by methylation of amino groups in the protein. The binding of the B oligomer allowed the A protomer to enter cells and to catalyze ADP-ribosylation of a membrane Mr 41 000 protein. The diverse biological activities of IAP occurring by this mechanism were mimicked by not only methylated IAP but also all hybrid toxins, indicating that the free amino groups in the protein were not essential for the enzyme activity of the A protomer and that the A protomer was able to enter cells if the B oligomer bound to cells "monovalently" via dimer 1. An additional effect of the B oligomer binding, i.e., the direct stimulation, without the transport of the A protomer, of cells leading to mitosis in lymphocytes in vitro or increases in circulating lymphocytes in vivo, was not mimicked by hybrid toxins containing methylated dimer 2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Structure-function relationship of islet-activating protein, pertussis toxin: biological activities of hybrid toxins reconstituted from native and methylated subunits. 396 80

3-Pyridine-carboxaldehyde and 3-pyridine-aldoxime were effective and specific inhibitors of the uptake of both nicotinic acid (NA) and nicotinamide (ND) by Bordetella pertussis, although neither compound inhibited the growth of the bacteria in liquid medium or the oxidation of glutamate by washed suspensions. In contrast, the following pyridine derivatives did not inhibit uptake of NA or ND: iso-NA, iso-ND, isoniazid, 6-amino-NA and 6-amino-ND, 3-acetyl-pyridine, 3-pyridyl-acetic acid, N,N-diethyl-ND and 3-pyridine-sulphonic acid. 3- Pyridyl-carbinol was inhibitory, but less so than the first listed compounds.
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PMID:Inhibition of nicotinic acid and nicotinamide uptake into Bordetella pertussis by structural analogues. 629 74

Preliminary evidence that Bordetella pertussis has a functional pyridine nucleotide cycle was the observation that [14C]-nicotinic acid was rapidly metabolized during its uptake by the bacteria to pyridine nucleotides and nicotinamide. Nicotinamide deamidase activity, necessary for the completion of the cycle by conversion of nicotinamide to nicotinic acid, was found in a soluble extract (20 000 X g supernatant) of B. pertussis cell lysates.
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PMID:Preliminary evidence for a pyridine nucleotide cycle in Bordetella pertussis. 632 69

The pyridine nucleotides have important non-redox activities as cellular effectors and metabolic regulators [1-3]. The enzyme-catalyzed cleavage of the nicotinamide-ribosyl bond of NAD+ and the attendant delivery of the ADPRibosyl moiety to acceptors is central to these many diverse biological activities. Included are the medically important NAD-dependent toxins associated with cholera, diphtheria, pertussis, and related diseases [4]; the reversible ADPRibosylation-mediated biological regulatory systems [5,6]; the synthesis of poly(ADPRibose) in response to DNA damage or cellular division [7]; and the synthesis of cyclic ADPRibose as part of an independent, calcium-mediated regulatory system [8]. As will be presented in this chapter, all evidence points to both the chemical and enzyme-catalyzed cleavage of the nicotinamide-ribosyl bond being dissociative in character via an oxocarbenium intermediate.
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PMID:NAD hydrolysis: chemical and enzymatic mechanisms. 789 70

The unmasking of the low concentration effect of angiotensin II (AII) was identified within the concentration ranges of 10(-13) to 10(-11) M of AII by PD 121981 (5-diphenylacetyl-1-(4-methoxy-3-methylbenzyl)- 4,5,6,7-tetrahydro-1H-imidazo[4,5-c]-pyridine-6-carboxylic acid) and 10(-12) to 3 x 10(-10) M of AII by CGP 42112 (nicotinic acid-Tyr-(N alpha-benzyl-oxycarbonyl-Arg)Lys-His-Pro-IIe-OH), AT2 antagonists, in association with the ordinary contraction curve, i.e., high concentration effect (at 3 x 10(-10)-10(-6) M of AII), in the rabbit abdominal aorta. Thus, they showed clear biphasic features of AII-induced contraction curves. However, this was not the case for angiotensin I and angiotensin III. This PD 121981-evoked low concentration effect of AII was selectively inhibited by DuP 753 (0.01-1 nM), dithiothreitol (10 and 100 microM), pertussis toxin (50 and 300 ng/ml, for 2 hr), nifedipine (1 and 10 microM) and 8-(diethylamino)octyl 3,4,5-trimethoxybenzoate hydrochloride (1 and 3 microM), which suggests the receptors were the AT1 subtype. However, the high concentration effect of AII was not affected by these drugs within the concentration ranges used in the present studies. These myographic results were almost consistent with the features of the intracellular Ca++ changes. Thus, it was concluded that the receptors that mediate the low concentration effect of AII belong to the AT1 subtype. However, the current study did not determine the mechanism by which PD 121981 and CGP 42112 evoked the up-regulation of the AT1 receptors.
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PMID:Characterization of PD 121981- and CGP 42112-induced unmasking of low concentration effects of angiotensin II in rabbit abdominal aorta. 799 73

Bordetella pertussis suppresses transcription of its virulence genes in response to specific environmental conditions, a response called modulation. The organism responds to high concentrations of SO4 and CIO4 ions, nicotinic acid, and nicotinic acid analogs in vitro; however, the in vivo modulator has not been identified. We investigated which chemical structures of the nicotinic acid molecule are important for modulation by testing various analogs for their ability to modulate. The ring nitrogen of nicotinic acid was not required, since benzoic acid was a modulator. In contrast, the carboxyl group was required, since derivatives like ethylnicotinate, 3-pyridylcarbinol, 3-acetyl pyridine, and 6-chloronicotinamide with altered carboxyl groups were not modulators. The planar ring structure or resonance in the ring was required for modulation, since nipecotic acid failed to modulate. The most potent modulators were nicotinic acid derivatives with electron-withdrawing substituents in the meta or para position relative to the carboxyl group. Relative hydrophilicity of substituents did not appear to contribute to modulation. Although these modulators elicited a clear biological response, the mechanism of modulation remains unclear, because no binding of the modulator 35SO4 or [14C]4-chlorobenzoic acid to whole B. pertussis was detected. However, modulation appears to involve a charge-charge interaction, since the response was blocked by chlorine ions.
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PMID:Characterization of environmental regulators of Bordetella pertussis. 843 1

Soluble guanylate cyclase (sGC) consisting of two different subunits (alpha: Mr = 74,000, beta: Mr = 69,000) was purified more than 12,000-fold in terms of specific activity from the supernatant of bovine lung homogenates and characterized. The heme content determined with the pyridine hemochromogen method and Bradford's protein assay was 0.8 heme per dimer. Cholera, pertussis, and botulinum C3 toxins modified exclusively the beta-subunit of sGC, yielding the ADP-ribose-bound compound with 1:1 stoichiometry, and Vmax for the cyclase reaction was increased 10 times by this modification. When the ADP-ribosylation of sGC was performed simultaneously with two or three bacterial toxins which have distinct amino acid specificities, the resultant enzyme had only one ADP-ribose, and the activity was the same as that of the enzyme modified with one toxin. When NO was incorporated into the reaction mixture containing the ADP-ribosylated sGC, the cyclase activity noticeably increased by approximately the same amount as that seen for the unmodified enzyme. Such effects were not seen with CO. When ADP-ribosylated sGC was incubated with Mn2+, the enzyme activity was synergistically increased. The heme-deleted sGC was also ADP-ribosylated by bacterial toxins and its activity was raised. These findings suggest that sGC has an ADP-ribosylation site near the GTP binding site, like other GTP-binding proteins, and that the beta-subunit regulates the activity.
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PMID:Purification of bovine soluble guanylate cyclase and ADP-ribosylation on its small subunit by bacterial toxins. 934 80

In C9 (Clone 9) liver cells, angiotensin 11 increased the intracellular Ca2+ content, inositol phosphate production and c-fos mRNA expression. Other angiotensins were also active with the order of potency being angiotensin II = angiotensin III >> angiotensin I > angiotensin IV. Losartan, but not PD 123177 (1-(4-amino-3-methyl)-5-diphenylacetyl-4,5,6,7-tetrahydro-1H-imida zo [4,5c]pyridine-6-carboxylic acid), blocked the effects of angiotensin II. Pertussis toxin did not alter these actions of angiotensin II. These data indicate that the effects were mediated through angiotensin AT1 receptors involving pertussis toxin-insensitive G-proteins. Phorbol myristate acetate was also able to increase c-fos mRNA expression. The action of angiotensin II was consistently greater than that of the active phorbol ester. Staurosporine but not genistein inhibited this effect of angiotensin II. Angiotensin II- and phorbol myristate acetate-induced proto-oncogene mRNA expression was attenuated in cells incubated overnight with the active phorbol ester, which suggests a major role of protein kinase C.
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PMID:Angiotensin AT1 receptors in Clone 9 rat liver cells: Ca2+ signaling and c-fos expression. 987 76

The effects of micro-, delta- and kappa-opioid receptor agonists, and orphanin FQ/nociceptin (Phe-Gly-Gly-Phe-Thr-Gly-Ala-Arg-Lys-Ser-Ala-Arg-Lys-Leu-Ala-Asn-Gln), on K+-induced [Ca2+]i increase were examined in SK-N-SH cells. Exposure to K+ (50 mM) resulted in a [Ca2+]i rise, which was blocked (-85%) by furaldipine (1 microM) and increased (63%) by BayK 8644 (methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethyl-pyridine-5 -carboxylate) (0.5 microM), indicating the involvement of L-type Ca2+ channels. The kappa-opioid receptor agonists 3,4-dichloro-N-Methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide (U-50488H) (1-50 microM) and 5,7,8-N-Methyl-N-[7-(1-pyrrolidinyl)-1-oxaspiro[4,5]dec-8-yl]benze neacetamide (U-69593) (25 microM), and the mu-opioid receptor agonist sufentanil (100 nM-3 microM) inhibited the amplitude of K+-induced [Ca2+]i increase. The agonist of the orphan opioid receptor, orphanin FQ/nociceptin (1 microM), induced dual excitatory and inhibitory effects on the depolarisation-induced Ca2+ influx. The effects of the opioid receptor agonists were not blocked by the kappa-opioid receptor antagonist nor-binaltorphimine (1 microM), only weakly prevented by naloxone (10-100 microM) and naltrexone (100 microM), and partially prevented by pertussis toxin (100 ng/ml, 24 h). The antagonist of the orphan opioid receptor, [Phe1psi(CH2-NH)Gly2]nociceptin(1-13)NH2 (1 microM), prevented the inhibitory effect of U-50488H, sufentanil and orphanin FQ. The present study provides pharmacological evidence for the presence of L-type Ca2+ channels in SK-N-SH cells, that are modulated by opioids through orphan opioid receptor activation.
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PMID:Effects of kappa- and mu-opioid receptor agonists on Ca2+ channels in neuroblastoma cells: involvement of the orphan opioid receptor. 1049 6

We have investigated the effects of the novel imidazoline compound (+)-2-(2-(4,5-dihydro-1H-imidazol-2-yl)-thiopene-2-yl-ethyl)-pyridine (NNC77-0074) on stimulus-secretion coupling in isolated pancreatic alpha- and beta-cells. NNC77-0074 stimulated glucose-dependent insulin secretion in intact mouse pancreatic islets. No effect was observed at </=2.5 mM glucose and maximal stimulation occurred at 10-15 mM glucose. NNC77-0074 produced a concentration-dependent stimulation of insulin secretion. Half-maximal (EC(50)) stimulation was observed at 24 microM and at maximally stimulatory concentrations insulin release was doubled. The stimulatory action of NNC77-0074 on insulin secretion was not associated with membrane depolarisation or a change in the activity of ATP-sensitive K(+) channels. Using capacitance measurements, we found that NNC77-0074 stimulated depolarisation-induced exocytosis 2.6-fold without affecting the whole-cell Ca(2+) current when applied via the extracellular medium. The concentration dependence of the stimulatory action was determined by intracellular application of NNC77-0074 through the recording pipette. NNC77-0074 stimulated exocytosis half-maximal at 44 nM and at maximally stimulatory concentrations the rate of exocytosis was increased twofold. NNC77-0074 stimulated depolarised-induced insulin secretion from islets exposed to diazoxide and high external KCl (EC(50)=0.45 microM). The stimulatory action of NNC77-0074 was dependent on protein kinase C activity. NNC77-0074 potently inhibited glucagon secretion from rat islets (EC(50)=11 nM). This was not associated with a change in spontaneous electrical activity and ATP-sensitive K(+) channel activity but resulted from a reduction of the rate of Ca(2+)-dependent exocytosis in single rat alpha-cells (EC(50)=9 nM). Inhibition of exocytosis by NNC77-0074 was pertussis toxin-sensitive and mediated by activation of the protein phosphatase calcineurin. In rat somatotrophs, PC12 cells and mouse cortical neurons NNC77-0074 did not stimulate Ca(2+)-evoked exocytosis, whereas the other imidazoline compounds phentolamine and efaroxan produced 2.5-fold stimulation of exocytosis. Our data suggest that the imidazoline compound NNC77-0074 constitutes a novel class of antidiabetic compounds that stimulates glucose-dependent insulin release while inhibiting glucagon secretion. These actions are exclusively exerted by modulation of exocytosis of the insulin- and glucagon-containing granules.
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PMID:Imidazoline NNC77-0074 stimulates insulin secretion and inhibits glucagon release by control of Ca(2+)-dependent exocytosis in pancreatic alpha- and beta-cells. 1267 59


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