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Biomedical subjects

G B Stefano

Publications and source records attributed to G B Stefano.

At least 145 records · Page 8Linked to original sources
PubMed1995

Hyperstimulation of leukocytes by plasma from cardiopulmonary by-pass patients is diminished by morphine and IL-10 pretreatment.

OBJECTIVE: The trauma of cardiopulmonary by-pass (CPB) in cardiac surgery results in a whole body diffuse inflammatory response characterized in part by hyperstimulation of leukocytes. Partially this is due to an increase in the release of biological response modifiers such as cytokines, as noted by the immunocyte stimulatory actions of cell-free plasma obtained postoperatively from CPB patients. The present study was conducted to determine whether CPB plasma induced immunocyte hyperstimulation can be prevented with naturally occurring immune inhibitory substances, specifically, interleukin (IL)-10 and/or morphine. EXPERIMENTAL DESIGN: Controlled in vitro study of the application of drugs to naive immunocytes to block the exitation caused by CPB-plasma. SETTING: University-based tertiary care hospital. PATIENTS: Plasma was obtained from ten patients undergoing CPB. Eligibility included admission for elective cardiac surgery, which no chronic illnesses or acute processes. INTERVENTIONS: Monocytes and granulocytes were pretreated with IL-10 and/or morphine before exposure to plasma obtained from patients undergoing CPB, as CPB-plasma would stimulate naive monocytes and granulocytes in a manner similar to that previously reported in CPB-patients. MEASURES: Computer-assisted microscopic image analysis, measuring cellular conformational and velocity changes, was used to evaluate the effect of treatment on the immunocytes response to stimulation with CPB-plasma. RESULTS: Pretreatment of cells with IL-10 and/or morphine significantly diminished the hyperstimulation induced by CPB-plasma in a concentration-dependent manner. In contrast, when the cells were initially or simultaneously exposed to CPB-plasma, IL-10 and/or morphine had no effect.

Anesthesia↗
PubMed1995

Naltrindole sensitive delta 2 opioid receptor mediates invertebrate immunocyte activation.

Previous studies demonstrated the presence of a delta 2 opioid receptor on human and invertebrate immunocytes. The present study demonstrates that this new binding site regulates invertebrate immunocyte activation. In the present study we note that the select delta antagonist, naltrindole, at a low concentration (10(-11) M), can significantly inhibit DAMA induced activation. Interestingly, the general opioid and opiate antagonist, naloxone, is not effective at this low concentration, further suggesting that the delta 2 opioid receptor mediates opioid immunocyte activation. This conclusion is further supported by the fact that DPDPE and DADLE, known to influence delta 1 activity did not affect immunocyte activation at low concentrations.

Animals↗
PubMed1995

Interleukin-4 potentiates voltage-activated Ca-currents in Lymnaea neurons.

The effect of interleukin-4 (IL-4) was studied on voltage-gated Ca-current of the neuron RPeD1 of Lymnaea stagnalis L. (Mollusca, Basommatophora), using two-microelectrode voltage-clamp method. It was found that: 1. The neuron RPeD1 possessed a high voltage-activated Ca-current characterized by -40 mV activation threshold and reaching its maximum at +5+5(-)+10 mV. The activation time constant of the current was found to be a monnexponential function of the membrane potential. Currents were almost completely inactivated within 200-300 ms. 2. IL-4 (10-200 U/ml) uniformly and reversibly increased the peak value of Ca-current in a dose- and time-dependent manner (at concentrations 75, 150 and 200 U/ml the potentiation was 5.3 +/- 1.8% (n = 3), 5.5 +/- 1. (n = 3) and 14.6 +/- 7.4% (n = 4), respectively. 3. No changes in the membrane resistance and holding current were observed during IL-4 application. 4. The time constants of activation and inactivation were not affected by IL-4. The maximal conductance as the only kinetic parameter was increased under the influence of IL-4. 5. The affect in modulation of HVA Ca-current caused by IL-4 was additive between the doses of 10-15o U/ml but saturated at concentrations > 200 U/ml. 6. IL-4 antiserum was a potent inhibitor for enhancement of Ca-current by IL-4.

Animals↗
PubMed1994

Microglia in invertebrate ganglia.

The results of this study lend strong support to the concept of the existence in insects and molluscs of a distinctive class of neuroglial cells comparable to vertebrate microglia. The evidence presented is as valid as that used in reference to the separate status of vertebrate microglia--i.e., the demonstration of a close structural and functional relationship of these cells with cells of the immune system. As in vertebrates, the excision of ganglia from three invertebrate species (the molluscs Planorbarius corneus and Mytilus edulis and the insect Leucophaea maderae) and their maintenance in incubation media led to an exodus of small cells and their accumulation in the culture dish. During this process, they underwent conformational changes from stellate to rounded, and then to more or less ameboid, comparable to those indicative of the process of activation in the animals' immunocytes. Functional characteristics which these translocated microglia-like cells share with immunocytes are motility, phagocytotic activity, and adherence to the culture dish. Furthermore, the two cells have certain biochemical features in common--e.g., the presence of certain cytokines and (at least in Planorbarius) that of corticotropin. An additional phenomenon of particular interest for the classification of microglial elements is their response to morphine. At 10(-6) M, this drug decreases not only the number of cells emerging from the excised ganglia but also the degree of their transformation to the "active" ameboid form. This dose-dependent and naloxone-sensitive effect of morphine on microglial cells parallels that on activated immunocytes of the same species. Corresponding results demonstrating an inhibitory effect of morphine on mobilized microglial cells of the frog Rana pipiens indicate that this relationship between the two cell types under consideration also exists in vertebrates. Binding and displacement experiments with membrane homogenates of microglial cells as well as immunocytes of Mytilus have shown that the effects of morphine on both cell types are mediated by the same special opiate receptor (mu 3).

Animals↗
PubMed1994

Inhibition of the calcitonin-induced outward current in identified Aplysia neurons by interleukin-1 and interleukin-2.

1. The effects of bath-applied recombinant human interleukin-1 (rhIL-1) and interleukin-2 (rhIL-2) on the calcitonin (CT)-induced outward current recorded from identified neurons (R9-R12) of Aplysia kurodai were investigated with conventional voltage-clamp and pressure ejection techniques. 2. Micropressure ejection of CT onto the soma of the neuron induced a slow outward current [Io(CT); 4-6 nA in amplitude, 30-40 sec in duration] associated with a decrease in input membrane conductance. 3. Io(CT) was increased by hyperpolarization. 4. The extrapolated reversal potential was +10 mV. Additionally, Io(CT) was sensitive to changes in (Na+)o but not to changes in (K+)o, (Ca2+)o, and (Cl-)o. 5. Micropressure-ejected forskolin produced a slow outward current similar to that induced by CT. 6. Bath-applied rhIL-1 and rhIL-2 (10-40 U/ml) reduced the CT-induced current in identified Aplysia neurons without affecting the resting membrane conductance or the holding current. 7. The inhibitory effects of both cytokines on the current were completely reversible. Heat-inactivated rhIL-1 and rhIL-2 were without effect. 8. These results suggest that the immunomodulators, IL-1 and IL-2, can modulate the CT-induced outward current associated with a decrease in Na+ conductance in the nervous system of Aplysia. Therefore, the study suggests that these cytokines may also serve as neuromodulators.

Animals↗
PubMed1994

Inhibitory effect of morphine on granulocyte stimulation by tumor necrosis factor and substance P.

We demonstrate that morphine, at higher concentrations than that effective in the inhibition of spontaneously active cells, can antagonize stimulation of human granulocytes by tumor necrosis factor (TNF) or substance P. The antagonistic effect appears to occur indirectly by way of downregulation of the cells' responsiveness to these stimulatory substances. We have previously shown that neutral endopeptidase 24.11 (NEP) is an important enzyme in neuro- and autoimmunoregulation of both vertebrates and invertebrates, and that activation of human granulocytes by monokines and neuropeptides results in regulation of NEP. Exposure of intact human granulocytes to morphine increases NEP by a naloxone-sensitive mechanism. The increased expression of NEP downregulates the stimulatory effect of substance P and TNF. In the case of substance P, we demonstrate the significance of NEP in modulating the process of downregulation by use of a specific NEP inhibitor, phosphoramidon. These results indicate that morphine is a significant factor in downregulating immunocyte responsiveness to NEP substrates and also to those signal molecules (i.e. cytokines) not metabolized by it. In summary, we infer that opiates may be endogenous signal molecules, a status that appears to be amply supported by their immunosuppressive actions.

Granulocytes↗
PubMed1994

Differential modulation of invertebrate hemocyte motility by CRF, ACTH, and its fragments.

Various reports have shown that invertebrate hemocytes are responsive to mammalian neuropeptides and cytokines. In the present study, we demonstrate that corticotropin-releasing factor (CRF) and adrenocorticotropin (ACTH) fragments (1-24), (1-4), (4-9), (1-13), (1-17), and (11-24) significantly stimulate molluscan hemocyte migration, and the whole sequence (1-39) and the fragment (4-11) have an inhibitory effect. Differences between species were found with respect to the response to individual fragments. Additionally, the (4-11) fragment was able to antagonize some of the stimulatory fragments (4-9) as well as tumor necrosis factor (TNF-alpha)-induced chemotaxis. Our results suggest that invertebrate hemocytes are able to respond to CRF and ACTH fragments that in turn provide further evidence of the complexity of intercellular signaling within the immune system in relatively primitive animals. Thus, auto- and neuroimmunoregulatory activities in mammals must have had an earlier beginning than previously believed.

Adrenocorticotropic Hormone↗
PubMed1994

The stress response and autoimmunoregulation.

Using the recent burgeoning of information on how the stress response systems interact, and combining this with advances in our understanding of neuroimmune communication, a proposed neuroendocrine-neuroimmune stress response system incorporating autoimmunoregulation is reviewed. The study of immunocyte behavior in certain clinical conditions associated with a variant stress response may help illuminate the functioning of the neuroendocrine-neuroimmune stress response system.

Animals↗
PubMed1993

Evidence for nitric oxide production and utilization as a bacteriocidal agent by invertebrate immunocytes.

The present study demonstrates that molluscan immunocytes are able to produce a chemical bacteriocidal substance which can be indirectly identified as nitric oxide (NO). The cells were analyzed in vitro on slides using computer-assisted microscopic image analysis to detect changes in cell conformation as well as to quantify the number of bacteria present. Sodium nitroprusside yields NO in solution causing bacterial clumping. The same phenomenon occurs in the presence of invertebrate immunocytes. Escherichia coli lipopolysaccharide also increases the number of bacteria found around the immunocytes, but this effect is selectively prevented by the addition of inhibitors of nitric oxide synthase, suggesting that this bacterial clumping is caused by the cells liberating NO. Interestingly the cells presumably producing NO maintain a round morphology. These findings suggest that immunocytes are able to kill bacteria by two mechanisms, i.e., phagocytosis and NO production.

Animals↗
PubMed1993

Opiate-like substances in an invertebrate, an opiate receptor on invertebrate and human immunocytes, and a role in immunosuppression.

The presence of morphine-like and codeine-like substances was demonstrated in the pedal ganglia, hemolymph, and mantle tissues of the mollusc Mytilus edulis. The pharmacological activities of the endogenous morphine-like material resemble those of authentic morphine. Both substances were found to counteract, in a dose-dependent manner, the stimulatory effect of tumor necrosis factor alpha or interleukin 1 alpha on human monocytes and Mytilus immunocytes, when added simultaneously to the incubation medium. The immunosuppressive effect of this opiate material expresses itself in a lowering of chemotactic activity, cellular velocity, and adherence. Codeine mimics the activity of authentic morphine, but only at much higher concentrations. Specific high-affinity receptor sites (mu 3) for morphine have been identified on human monocytes and Mytilus immunocytes. In Mytilus recovering from experimentally induced stress, the return of "altered" immunocytes to a more inactive state appears to be due to a significant rise in the content of morphine-like material in the pedal ganglia and hemolymph at this time. Thus, morphine may have a role in calming or terminating the state of immune alertness.

Animals↗
PubMed1993

Schistosoma mansoni: an enkephalinergic system that may participate in internal and host-parasite signaling.

The present study is concerned with an opioid system in the human trematode Schistosoma mansoni, both as part of the endogenous chemical messenger system and as a tool in the parasite reaction to the host(s). A high-affinity opioid binding site was characterized in membrane suspensions prepared from adult worms. Scatchard analysis revealed a single class of receptors with a dissociation constant of 1.8 nM and a Bmax of 24.9 pmol/g protein for (D-Ala2, Met5)-enkephalin (DAME). The displacement experiments demonstrated that the most potent ligands were beta-endorphin, DAME, and met-enkephalin. These characteristics and the effects of various ions on DAME affinity suggest that S. mansoni has a delta-like opioid receptor, as previously described in other invertebrates. A met-enkephalin-like peptide was also characterized in a miracidial extract. Radioimmunoassay, reverse-phase HPLC, and bioassay by induction of cell conformational changes of human polymorphonuclear leukocytes revealed that the parasite peptide is very similar to authentic met-enkephalin. A met-enkephalin-like peptide was also shown to be present in adult worms and in their incubation medium. Taken together, these observations demonstrate the existence of a complete opiate system in S. mansoni. We discuss its role in molecular signaling within the parasite and in host-parasite interactions.

Animals↗
PubMed1993

Neuropeptide Y inhibits human and invertebrate immunocyte chemotaxis, chemokinesis, and spontaneous activation.

1. In a concentration-dependent manner neuropeptide Y was found to be a potent inhibitor of the spontaneous activation of human granulocytes and macrophages as well as Mytilus edulis immunocytes. 2. Neuropeptide Y also inhibited the chemotaxic response of these immunocytes to the chemoattractant f-MLP. 3. Incubation of both the human and the invertebrate immunocytes in f-MLP (10(-9) M) causes "activation" as noted by random locomotion (chemokinesis). Neuropeptide Y also blocked f-MLP-induced chemokinesis. 4. The results suggest that neuropeptide Y may, in addition to other functions, serve as an endogenous regulator of immunocyte function.

Animals↗
PubMed1993

Selective effects of human immunodeficiency virus (HIV) gp120 on invertebrate neurons.

1. HIV gp120 selectively reduces the glutamate-induced inward current and the acetylcholine-induced outward current in specific and identified Aplysia neurons without affecting dopamine (DA)- and serotonin (5-HT)-induced responses. 2. gp120 specifically decreases DA levels without significantly altering norepinephrine and 5-HT levels in Mytilus pedal ganglia. 3. The gp120-associated decrease in DA levels in Mytilus is dose dependent and exhibits a threshold level. 4. The alteration of in vitro DA levels is specific for gp120 since anti-gp120 blocks the effect. 5. gp120 and its effects appear to be stable due to the duration of treatment and the failure of secondary effects to materialize following antibody treatment.

Acetylcholine↗
PubMed1993

Human neutrophil and macrophage chemokinesis induced by cardiopulmonary bypass: loss of DAME and IL-1 chemotaxis.

Cardiopulmonary bypass (CPB) induces both cellular immunosuppression and an inflammatory response. In an effort to better characterize CPB-induced immune dysfunction, we examined the chemotaxic ability of human granulocytes and macrophages to D-Ala2-Met-enkephalin (DAME) and interleukin (IL)-1 alpha with computer-assisted microscopic image analysis before, during and after CPB. Spontaneous granulocyte and macrophage activation increased from 6% and 8% (before) to 52% and 44% (during) and then 39% and 31% after (38 h) CPB, respectively. These activated cells, characterized by conformational changes and locomotion, exhibited chemokinesis. Furthermore, no direct response to either DAME or IL-1 alpha was observed in the bypass and postoperative specimens. Cellular velocity was 0.14 and 0.07 microns s-1 for control spontaneously activated granulocytes and macrophages, respectively, and equal to the velocity observed for DAME and IL-1 alpha exposed cells, during and after CPB. CPB-unexposed cells, influenced only by the chemotaxic agents, exhibited a 3-4-fold increase in their velocity. Additionally, the migratory path of the activated cells obtained during and after CPB exhibited chemokinesis, rather than chemotaxis, when placed in a concentration gradient of either signal molecule. Cells exposed to fentanyl, the anesthetic agent, exhibited the same behavior as controls, as did those treated with morphine sulphate. However, at higher concentrations (> or = 10 ng ml-1) fentanyl and morphine reduced granulocyte and macrophage activity, demonstrating that CPB caused the opposite effect of fentanyl and also that CPB exposure overcame the pharmacological inhibitory effect of the mu opiate ligands.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiopulmonary Bypass↗