Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neuropeptide Y (NPY) has been shown to be capable of both the enhancement and suppression of gonadotropin secretion from pituitary cells. In order to elucidate the underlying cellular mechanisms which might account for these actions, we have examined the effects of NPY on gonadotropin secretion stimulated by either cell depolarization or by GnRH from primary cultures of rat pituitary cells. In one set of experiments, we measured single-cell [Ca2+]i using the Ca2(+)-sensitive intracellular fluorescent indicator Fura-2, in gonadotropes which had been identified using a reverse hemolytic plaque assay employing an antiserum to LH. In another group of investigations, we measured FSH and LH secretion in response to depolarization or stimulation with GnRH, and examined the influence of NPY on these patterns of secretion. NPY was active in inhibiting the amplitude of the [Ca2+]i signal induced by depolarization with 20 mM K+, as well as in substantially blocking the secondary plateau phase of the GnRH-induced elevation of [Ca2+]i. However, the peak [Ca2+]i transients occurring in response to either depolarization with 50 mM K+ or the initial phase of the GnRH-induced response, were not sensitive to blockade by NPY. Moreover, treatment of the cells for 24 h with pertussis toxin prevented the NPY-mediated inhibition of the GnRH-stimulated [Ca2+]i plateau. Cell depolarization by 50 mM K+ induced 3-fold increases in FSH and LH release over 2-h incubations. GnRH (100 nM) elicited a 9-fold increase in FSH and a 14-fold stimulation of LH over the same time period. NPY had insignificant effects upon depolarization-induced hormone release, but at 1 microM partially suppressed LH release elicited by 100 nM GnRH over 2 h. We conclude that NPY is capable of inhibiting [Ca2+]i signals in gonadotropes that are stimulated by GnRH, and that these effects are mediated through activation of a pertussis toxin-sensitive G-protein. These effects on [Ca2+]i may underly the inhibitory effects of NPY on gonadotropin secretion.
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PMID:Direct neuropeptide Y-induced modulation of gonadotrope intracellular calcium transients and gonadotropin secretion. 210 84

The effects of dopamine (DA) on voltage-dependent potassium currents were investigated in rat lactotrophs maintained in primary culture. Lactotroph cells were identified using the reverse hemolytic plaque assay. Membrane currents and potentials of lactotroph cells were recorded using the patch-clamp recording technique in the 'whole-cell' configuration. In the presence of cobalt (2 mM), two types of voltage-dependent K+ currents were recorded, a voltage-activated delayed K+ current (IK) and a voltage-activated transient K+ current (IA). The current IK was activated at membrane potentials varying from -20 to +40 mV and did not inactivate during prolonged voltage steps (up to 25 s); it was blocked by tetraethylammonium (10 mM). The current IA was activated at membrane potentials higher than -45 mV and showed a voltage-dependent inactivation between -110 and -40 mV; it was slightly inhibited by 4-aminopyridine (5 mM). Under current-clamp conditions, the majority of the cells (60%) showed spontaneous Ca2(+)-dependent action potentials (APs) while silent cells (40%) were excitable by depolarizing current pulses. Bath application of 10 nM DA evoked a hyperpolarizing response, blocked spontaneous APs and decrease the amplitude of evoked APs. Only the hyperpolarizing response faded during the course of the whole cell recording experiments. Under voltage-clamp conditions, DA induced a reversible increase in both voltage-dependent outward K+ currents, without modifying their thresholds. Steady-state inactivation of IA was not affected by DA. These DA-induced responses were dose-dependent and they involved D2 receptor activation. They were mimicked by the specific D2 receptor agonist bromocriptine (10 nM) and blocked by the specific D2 receptor antagonist sulpiride (100 nM), the D1 antagonist SCH 23390 being ineffective. The ability of DA to increase voltage-dependent K+ currents cannot be observed without GTP in the recording pipette. It was pertussis-toxin-sensitive but was affected neither by bath application of 1 mM forskolin nor by the presence of 500 microM cyclic AMP with 500 microM 3-isobutyl-1-methylxanthine in the pipette solutions. We conclude that in lactotroph cells DA specifically increases two voltage-dependent K+ currents via a pertussis-toxin-sensitive guanine nucleotide regulatory protein and appears to be independent of intracellular cyclic AMP. This effect leads to a decrease in the excitability of the cell, explaining in part the inhibitory effect of DA on prolactin release.
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PMID:Effects of dopamine on voltage-dependent potassium currents in identified rat lactotroph cells. 214 27

The degradation of elastic fibres during atherosclerotic plaque formation in arterial wall is a well known process. The liberated elastin peptides such as K-elastin possess various biological activities: They are chemotactic for monocytes and fibroblasts, stimulate the oxidative burst and the intracellular free Ca2+ mobilisation through the phosphatidylinositol (PIP2) breakdown in PMNLs. It was found that the PIP2 breakdown induced by K-elastin is a pertussis toxin sensitive process in PMNLs of young subjects. In the case of the elderly, the K-elastin-induced oxidative burst, intracellular free Ca2+ elevation was less than in young, and could not be inhibited by pertussis toxin. Studying the K-elastin-induced inositol phosphate (IP) formation in PMNLs of elderly a disturbed PIP2 breakdown was found. K-elastin stimulated the IP formation at a very low level in PMNLs of elderly. This alteration of the second messenger formation (e.g. IP3 and Ca2+) after KE stimulation, might be the consequence of their originally elevated levels in resting PMNLs of elderly.
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PMID:Altered phosphatidylinositol breakdown after K-elastin stimulation in PMNLs of elderly. 215 16

Lymphotoxin (LT) can activate human neutrophils. Using a hemolytic plaque assay to detect secretion of lactoferrin and myeloperoxidase (MPO) from single adherent neutrophils, we showed that LT induced secretion from both primary and secondary granules. Incubation of cells with cytochalasin B was required for MPO secretion, and it enhanced lactoferrin secretion. Pertussis toxin, which blocks a G-protein in the plasma membrane, inhibited LT-induced exocytosis of MPO, but not of lactoferrin. Incubation with LT did not induce any detectable changes of the cytoplasmic free [Ca2+] in neutrophils. On the other hand, secretion of granule proteins from adherent neutrophils in response to LT was blocked by loading neutrophils with quin-2 in order to increase the intracellular calcium buffering capacity. This was achieved at a concentration of quin-2, at which the secretion induced by the phorbol ester PMA and the chemotactic peptide FMLP was unaffected. Trifluoroperazine (TFP), a dual protein kinase C and calmodulin inhibitor, significantly inhibited the LT-mediated secretion of lactoferrin from adherent granulocytes. The PMA effect was unaltered by TFP under these conditions, suggesting that the inhibitory effect was on a calcium-calmodulin dependent step. The secretion induced by TNF and GM-CSF was also blocked by buffering changes in the intracellular [Ca2+] and inhibited to a similar extent by TFP. Our results suggest that calmodulin and minute changes in the cytoplasmic free [Ca2+] may be involved in a common signal transduction pathway engaged in activation of adherent neutrophils by several cytokines.
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PMID:Lymphotoxin induces secretion of granule proteins from adherent neutrophils: possible role of intracellular free calcium. 216 92

The effects of dopamine (DA) on voltage-dependent Ca2+ currents were investigated in cultured rat lactotroph cells using the patch clamp recording technique. Each recorded cell was identified by the reverse hemolytic plaque assay. In the whole-cell configuration, two types of Ca2+ currents, L and T, were characterized on the basis of their kinetics, voltage sensitivity, and pharmacology. The L component had a threshold of -25 mV, showed little inactivation during a 150-msec voltage step, and was maximal at +10 mV. Cadmium ions (100 microM) significantly reduced its amplitude (75%). The T component was activated at a membrane potential close to -50 mV, was maximal at -10 mV, and showed a voltage-dependent inactivation between -90 and -30 mV. It was quickly inactivated during a maintained depolarization (time constant, 27 ms at -30 mV) and was strongly reduced (80%) by nickel ions (100 microM). Bath application of DA (10 nM) caused a markedly general depression of inward Ca2+ currents, acting differently on the T- and L-type currents. DA application shifted the voltage-dependence of the L-type current activation toward depolarization values (8 mV) without modifying its time- and voltage-dependent inactivation. In contrast, DA enhanced the inactivation of the T-type current by accelerating its time-dependent inactivation (25% decrease in the time constant of inactivation) and by shifting the voltage-dependence of the T-type current inactivation toward hyperpolarizing values (-63 mV in control vs. -77 mV in the presence of DA). These effects of DA were dose-dependent and involved the activation of a D2 receptor type. They were mimicked by bromocriptine application (10 nM), whereas sulpiride (100 nM) blocked the DA-evoked response. The D1 antagonist SCH 23390 was ineffective up to 100 microM. All of these DA-induced modifications in Ca2+ currents were abolished using a GTP-free pipette solution or after pretreatment of cells with pertussis toxin, suggesting that DA can regulate the function of Ca2+ channels through GTP-binding proteins (G-proteins). Our results show that DA acts simultaneously by reducing both voltage-dependent Ca2+ currents on lactotroph cells. Thus, DA reduces the entry of Ca2+ ions across the surface membrane and thereby influences electrical activity and the cytosolic free Ca2+ concentration involved in both basal and evoked PRL release.
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PMID:Dopamine inhibits two characterized voltage-dependent calcium currents in identified rat lactotroph cells. 216 20

A study was made of the suppressorgenic action of killed whole-cell pertussis vaccine prepared from B. pertussis strains 475 and 305. Thymic and splenic lymphocytes of CBA mice 3-7 days following intraperitoneal or intravenous inoculation of pertussis vaccine were shown to inhibit in an antigen-nonspecific manner the plaque-forming cell (PFC) production in the adoptive transfer experiments. Suppression of graft-versus-host reaction was also observed, estimated by the survival of irradiated (CBA X C57BL/6) Fl mice, or by measuring the endogenous colony formation. Suppression-mediating cells were found to be susceptible to complement-dependent lysis by the anti-I-Jk alloantiserum against the specific marker of suppressor T cells, antigen I-J. Furthermore, thymocytes of pertussis vaccine-treated mice were shown to inhibit the endogenous colony formation in syngeneic mice irradiated in sublethal dose. Thus, B. pertussis vaccination of CBA mice resulted in appearance of suppressor T cells that exerted various inhibitory activities in several experimental test-systems.
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PMID:[Antigen-nonspecific suppression of the immune response in mice as affected by pertussis vaccine]. 244 48

Both TNF and and granulocyte/macrophage CSF (GM-CSF) can activate neutrophils. The aim of this work was to determine the effect of these cytokines on neutrophil degranulation. The secretion of lactoferrin of secondary granules and myeloperoxidase (MPO) of primary granules from single adherent human neutrophils was assayed by use of a reverse hemolytic plaque assay. Both rTNF and rGM-CSF caused secretion of lactoferrin in a dose-dependent manner. Both agents also caused secretion of MPO, but only in the presence of cytochalasin B. Preincubation with pertussis toxin inhibited rGM-CSF-induced secretion of both lactoferrin and MPO. rTNF-induced MPO secretion was also blocked by pertussis toxin, whereas lactoferrin secretion was only slightly affected. Neither rTNF nor rGM-CSF caused any detectable changes in the concentration of cytoplasmic free Ca2+ in fura-2-loaded cells. However, when neutrophils were loaded with increasing concentrations of quin-2 to buffer any local, not detectable, changes in the concentration of cytoplasmic Ca2+, both rTNF- and rGM-CSF-induced secretion of lactoferrin and MPO were almost totally abolished at a relatively low quin-2 concentration. These results suggest a role of a regulatory G-protein and minute local changes in the concentration of cytoplasmic Ca2+ in TNF- and GM-CSF-induced neutrophil degranulation.
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PMID:Effect of tumor necrosis factor and granulocyte/macrophage colony-stimulating factor on neutrophil degranulation. 265 22

A temporal relationship has been demonstrated between persisting immune complexes and non-antigen-specific immunodepression. Mice were given intraperitoneal injections of Bordetella pertussis at weekly intervals. After 7 weeks they developed circulating immune complexes, the levels of which increased with continued administration of pertussis. The increase in immune complex levels was accompanied by a diminished primary immune response to intraperitoneally injected sheep erythrocytes (SRBC) as judged by a reduction in their direct and indirect plaque-forming cell response and serum agglutination titres. Spleen cells from immunodepressed pertussis-treated mice were transferred to irradiated normal recipients and displayed a normal response to SRBC. By contrast, spleen cells transferred from normal donors to irradiated pertussis-treated recipients had an impaired response to SRBC. Thus, the immunodepression caused by pertussis treatment is a property of the environment and not the lymphocytes themselves. It is considered that chronic circulating immune complexes induced by pertussis administration may cause non-antigen-specific immunodepression.
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PMID:Relationship between non-antigen-specific immunodepression and persisting immune complexes induced by pertussis in mice. 287 21

Endotoxin protein represents a group of immunobiologically active p polypeptides which are associated with the lipopolysaccharide endotoxin in the outer membrane of Gram-negative bacteria. To study the adjuvant effect of endotoxin protein, CF-1 mice were immunized intraperitoneally with graded doses of glutaraldehyde-inactivated cholera toxoid with and without endotoxin protein prepared from Bordetella pertussis, Salmonella typhi or Vibrio cholerae. Immune responsiveness was assessed by measuring resistance to intravenous challenge with cholera enterotoxin and by serum antitoxin responses. The results showed that endotoxin protein from S. typhi can enhance the 50% protective dose (PD50) of cholera toxoid five to 12-fold, the endotoxin protein from V. cholerae enhances the PD50 six to seven fold at most, but the endotoxin protein from B. pertussis can enhance the PD50 some 27-fold. Furthermore, within the variability of both the mouse protection test and the rabbit intracutaneous assay of toxin induced vascular permeability, mouse serum neutralizing antitoxin levels correlated with the greater degree of resistance of the mice to the toxin challenge. The adjuvant effect also has been demonstrated by measuring the appearance of antitoxin specific plaque forming cells derived from mouse lymphocyte cultures. After seven days of culture in the presence of endotoxin protein and cholera toxoid, the number of plaque forming cells to cholera toxin coated sheep erythrocytes was enhanced some 28 times as compared to the cultures exposed to the cholera toxoid alone.
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PMID:The adjuvant effect of pertussis endotoxin protein in modulating the immune response to cholera toxoid in mice. 287 8

Mice were immunized by intraperitoneal (ip) or respiratory administration of ultraviolet-inactivated virus alone or with Bordetella pertussis extract (BPE) as an adjuvant. The effect of immunization was tested by determination of antibody titers and by survival of a lethal challenge with 200 LD(50) of a virulent (large-plaque variant) strain of EMC virus. For plain vaccine the ip 50% effective dose (ED(50)) was 37 hemagglutination units (HAU; ca. 4 x 10(6) plaque-forming unit equivalents); with adjuvant the ip ED(50) was reduced to 20 HAU. After respiratory immunization by intratracheal injection, an ED(50) value of 100 HAU was found, which was not affected by BPE. After ip vaccination the primary immune response was enhanced by BPE, but the challenge response, measured 3 weeks after challenge, was unaffected. Respiratory immunization induced a primary response which was not influenced by BPE, but here the challenge response was enhanced by the adjuvant. After secondary treatment (challenge or booster vaccination) serum antibodies and protection against challenge persisted for at least 1 year.
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PMID:Immunization of mice against encephalomyocarditis virus. II. Intraperitoneal and respiratory immunization with ultraviolet-inactivated vaccine: effect of Bordetella pertussis extract on the immune response. 434 27


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