Biomedical subjects

I D Welters

Publications and source records attributed to I D Welters.

12 recordsLinked to original sources

PubMed2001

Inhibitory effects of S-(-) and R-(+) bupivacaine on neutrophil function.

BACKGROUND: Local anesthetics inhibit migration, enzyme release and superoxide anion generation of polymorphonuclear leukocytes (PMN). Due to their ability to phagocytose and kill bacteria PMN represent a major defense mechanism in the circulating blood. In this study we determined the influence of racemic bupivacaine and its enantiomers on neutrophil phagocytic activity, oxidative burst as well as surface expression of complement and Fcgamma receptors. METHODS: Venous blood was pre-incubated with different concentrations of either racemic bupivacaine, R-(+) or S-(-) bupivacaine. Fluoresceine isothiocyanate (FITC)-labeled antibodies against Fcgamma receptor III (CD16), complement receptor 1 (CD35) and complement receptor 3 (CD11b) were used to determine surface receptor expression. Phagocytic activity was measured by ingestion of FITC-labeled vital Staphylococcus aureus. Oxidative burst was determined by conversion of nonfluorescent dihydrorhodamine 123 into fluorescent rhodamine 123. Fluorescent intensity of each sample was determined by flow cytometry. RESULTS: Racemic bupivacaine inhibited surface receptor expression, phagocytosis, and oxidative burst in a time- and concentration-dependent manner. Although the S-(-) enantiomer exerted significantly less inhibitory action on neutrophil function compared to R-(+) and racemic bupivacaine, these effects were small compared to the overall changes. CONCLUSION: These findings suggest that bupivacaine impairs surface receptor expression and may thereby contribute to reduced phagocytic activity and oxidative burst. Enantiomer-specific effects of bupivacaine may play a minor role in the inhibition of these leukocyte functions.

Adult↗

PubMed2000

Processing of proenkephalin-A in bovine chromaffin cells. Identification of natural derived fragments by N-terminal sequencing and matrix-assisted laser desorption ionization-time of flight mass spectrometry.

A large variety of proenkephalin-A-derived peptides (PEAPs) are present in bovine adrenal medulla secretory granules that are cosecreted with catecholamines upon stimulation of chromaffin cells. In the present paper, after reverse phase high performance liquid chromatography of intragranular soluble material, PEAPs were immunodetected with antisera raised against specific proenkephalin-A (PEA) sequences (PEA63-70 and PEA224-237) and analyzed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Thirty PEAPs were characterized in addition to enkephalins and whole PEA, indicating that preferential proteolytic attacks occurred at both N- and C-terminal regions. A similar approach was used to characterize PEA-derived fragments exocytotically released into the extracellular space that showed five additional minor PEAPs. Among all these naturally generated peptides, enkelytin, the antibacterial bisphos- phorylated C-terminal peptide (PEA209-237), was predominantly generated, as shown by MALDI-TOF mass spectrometry analysis, which constituted an efficient method for its identification. Finally, the data on PEA intragranular and extracellular processing in adrenal medulla are discussed in regard to the known enzymatic processing mechanisms. We note the high conservation of the cleavage points in evolutionarily diverse organisms, highlighting an important biological function for the released PEAPs.

Adrenal Medulla↗

PubMed2000

Morphine suppresses complement receptor expression, phagocytosis, and respiratory burst in neutrophils by a nitric oxide and mu(3) opiate receptor-dependent mechanism.

We investigated whether morphine and fentanyl influence surface receptor expression, phagocytic activity and superoxide anion generation of neutrophils in a whole blood flow cytometric assay. Morphine suppressed complement and Fcgamma receptor expression and neutrophil function in a concentration- and time-dependent manner. Morphine-induced changes were similar to those caused by the nitric oxide (NO) donor S-nitroso-N-acetyl-penicillamine and were abolished by preincubation with the NO synthase inhibitor N-nitro-L-arginine as well as naloxone. Fentanyl had no immunosuppressive effects. These results suggest that these neutrophil functions are inhibited by morphine-stimulated NO release mediated by the mu(3) opiate receptor subtype found on immunocytes.

Fentanyl↗

PubMed2000

Ascaris suum, an intestinal parasite, produces morphine.

The parasitic worm Ascaris suum contains the opiate alkaloid morphine as determined by HPLC coupled to electrochemical detection and by gas chromatography/mass spectrometry. The level of this material is 1168 +/- 278 ng/g worm wet weight. Furthermore, Ascaris maintained for 5 days contained a significant amount of morphine, as did their medium, demonstrating their ability to synthesize the opiate alkaloid. To determine whether the morphine was active, we exposed human monocytes to the material, and they immediately released nitric oxide in a naloxone-reversible manner. The anatomic distribution of morphine immunoreactivity reveals that the material is in the subcuticle layers and in the animals' nerve chords. Furthermore, as determined by RT-PCR, Ascaris does not express the transcript of the neuronal mu receptor. Failure to demonstrate the expression of this opioid receptor, as well as the morphine-like tissue localization in Ascaris, suggests that the endogenous morphine is intended for secretion into the microenvironment.

Animals↗

PubMed2000

[The effect of different volume expanders on neutrophil granulocyte function in vitro].

INTRODUCTION: The influence of kolloids on the immune system is not well documented. In this study we investigated the effects of gelatine, hydroxyethylstarch (HES), human albumine, and dextrane on neutrophil function and receptor expression by flow cytometry. METHODS: Whole blood of healthy volunteers was incubated for 30 minutes with either gelatine, HES (6% and 10%), dextrane 40 and 60, or human albumin 20%. Phagocytic capacity was determined by uptake of fluorescein-isothiocyanate labeled bacteria, the conversion of dihydrorhodamine 123 into fluorescent rhodamine 123 was used for oxidative burst measurements. Expression of complement receptors CD 11b and CD35 was investigated using fluorescein-isothiocyanate labeled antibodies. RESULTS: Incubation with gelatine significantly increased expression of complement receptors and oxidative burst. Dextranes and HES had no influence on neutrophil function. Human albumin reduced the oxidative burst, whereas CD 35 expression was increased. CONCLUSION: The physiological significance of these changes in a range of 10% has to be clarified in further investigations.

Bacteria↗

PubMed2000

Postoperative nausea and vomiting after Faden operation.

OBJECTIVE: The purpose of this study was to evaluate the antiemetic effect of prophylactic dimenhydrinate application prior to Faden operation and to compare the incidence of PONV between bimedial Faden operation (BMF) and horizontal recess-resect procedure (R&R). METHODS: Ninety-nine children (4-10 years) scheduled for BMF were included in this prospective double-blind study. Midazolam (0.5 mg/kg body weight, BW) was administered orally for premedication 30 min before induction of anesthesia. Additionally, children weighing >/=23 kg received either dimenhydrinate suppositories or placebo. The placebo group was compared with 148 children who underwent R&R surgery without antiemetic prophylaxis during the same period. Anesthesia was induced with thiopentone (5-10 mg/kg BW) and vecuronium (0.1 mg/kg BW) bromide and maintained with halothane (1-2 vol%) in N(2)O/O(2) (65/35 vol%). Age, height, weight, and incidence of oculocardiac reflex were documented. PONV was classified into "no vomiting", "vomiting without therapy", and "vomiting requiring rescue medication". In the latter case dimenhydrinate was given again. The chi-square test was used for statistical analysis. RESULTS: Forty-eight patients received placebo, while 51 received dimenhydrinate. No differences between any groups were observed concerning age, height, weight, and incidence of oculocardiac reflex. Compared to R&R surgery, PONV requiring rescue medication occurred significantly more frequently after BMF (45% vs 23% after R&R). PONV after BMF was significantly less severe in the dimenhydrinate group than in the placebo group. The total incidence of PONV after BMF, however, was not significantly reduced. CONCLUSION: The high incidence of PONV after BMF can be explained by the greater invasiveness of BMF than R&R surgery. PONV requiring antiemetic rescue medication can be reduced by preoperative administration of dimenhydrinate suppositories.

Anesthesia, Local↗

PubMed2000

Endogenous morphine.

It is now well accepted that endogenous morphine is present in animals, both in invertebrates and vertebrates. It is a key signaling molecule that plays an important role in downregulating physiological responses, such as those in the immune system, including immune elements in the CNS. It has been demonstrated that a specific mu-opiate-receptor subtype, mu3, mediates these downregulatory effects through release of NO. This article examines morphine as an endogenous signaling molecule, in terms of its role in neural and immune regulation.

Animals↗

PubMed2000

Basal nitric oxide limits immune, nervous and cardiovascular excitation: human endothelia express a mu opiate receptor.

Nitric oxide (NO) is a major signaling molecule in the immune, cardiovascular and nervous systems. The synthesizing enzyme, nitric oxide synthase (NOS) occurs in three forms: endothelial (e), neuronal (n) and inducible (i) NOS. The first two are constitutively expressed. We surmise that in many tissues there is a basal level of NO and that the actions of several signaling molecules initiate increases in cNOS-derived NO to enhance momentary basal levels that exerts inhibitory cellular actions, via cellular conformational changes. It is our contention that much of the literature concerning the actions of NO really deal with i-NOS-derived NO. We make the case that cNOS is responsible for a basal or 'tonal' level of NO; that this NO keeps particular types of cells in a state of inhibition and that activation of these cells occurs through disinhibition. Furthermore, naturally occurring signaling molecules such as morphine, anandamide, interleukin-10 and 17-beta-estradiol appear to exert, in part, their beneficial physiological actions, i.e., immune and endothelial down regulation by the stimulation of cNOS. In regard to opiates, we demonstrate the presence of a human endothelial mu opiate receptor by RT-PCR and sequence determination, further substantiating the role of opiates in vascular coupling to NO release. Taken together, cNOS derived NO enhances basal NO actions, i.e., cellular activation state, and these actions are further enhanced by iNOS derived NO.

Animals↗

PubMed2000

NF-kappaB, nitric oxide and opiate signaling.

NF-kappaB, a DNA binding factor, has been implicated in inflammatory cytokine activation. NF-kappaB is activated by IkappaBalpha, its inhibitor, which is phosphorylated and proteolytically degraded. In this regard, NF-kappaB is also responsive to reactive oxygen intermediates and calcium. Reports also have emerged that demonstrate that nitric oxide inhibits NF-kappaB transcriptional activation in a variety of cells, including monocytes and endothelial cells. Recently, we have demonstrated that morphine, not opioid peptides, via the mu3 opiate receptor is coupled to constitutive nitric oxide release in these same cells. In this regard, we provide a scenario whereby morphine modulates NF-kappaB activation via nitric oxide. This pathway appears to be the key step in regulating inducible nitric oxide synthase expression, controlling the balance between constitutive nitric oxide synthase and the inducible form.

Animals↗

PubMed2000

Reduction of postoperative nausea and vomiting by dimenhydrinate suppositories after strabismus surgery in children.

UNLABELLED: Although dimenhydrinate has been used for treatment and prevention of postoperative nausea and vomiting (PONV) since the fifties, there have been few controlled studies about its efficacy. We performed a double-blinded study of 301 children aged 4 to 10 yr who underwent strabismus surgery. Preanesthetic medication with midazolam (0.5 mg/kg) as well as application of either dimenhydrinate suppositories or a placebo preparation was performed 30 min before the induction of anesthesia. Anesthesia was induced with thiopentone (5-10 mg/kg) and vecuronium (0.1 mg/kg) and maintained with halothane (1%-2%) in N(2)O/O(2) (65%/35%). The incidence of PONV, requirements for rescue dimenhydrinate, and time to recovery were recorded. The overall incidence of PONV was 60.1% in the placebo group and 30.7% in the dimenhydrinate group. In the dimenhydrinate group, children had to be observed in the recovery room significantly longer than those in the placebo group. Children having received dimenhydrinate were discharged from the recovery room with lower arousal scores. We conclude that the rectal administration of dimenhydrinate is effective for the prevention of PONV, although the sedative effect may require longer postoperative monitoring. IMPLICATIONS: We performed a double-blinded, randomized study to investigate the effects of prophylactic rectal dimenhydrinate application on postoperative nausea and vomiting in children undergoing strabismus surgery. In comparison with placebo, dimenhydrinate reduced the incidence of postoperative vomiting from 60.1% to 30.7%.

Anesthesia, Inhalation↗

PubMed2000

Morphine inhibits NF-kappaB nuclear binding in human neutrophils and monocytes by a nitric oxide-dependent mechanism.

BACKGROUND: The transcription factor NF-kappaB plays a pivotal role in gene expression of inflammatory mediators such as cytokines or adhesion molecules. NF-kappaB-mediated transcriptional activation of these genes is inhibited by nitric oxide (NO) in a variety of cells, including monocytes. Morphine mediates NO release in a naloxone antagonizable manner in monocytes and neutrophils. METHODS: The influence of morphine on NF-kappaB activation was investigated in a whole-blood flow cytometric assay. A specific antibody against the p65 subunit of NF-kappaB was used and detected by fluoresceine-isothiocyanate-labeled anti-immunoglobulin G. Nuclei were stained with propidium iodide. Leukocyte subpopulations were evaluated by gating on neutrophils and monocytes. The median fluorescence channel was determined. Different morphine concentrations (50 nm, 50 microm, 1 mm) and incubation intervals (10-150 min) were used. RESULTS: Morphine inhibits lipopolysaccharide-induced NF-kappaB nuclear binding in human blood neutrophils and monocytes in a time-, concentration-, and naloxone-sensitive-dependent manner. Similar effects were achieved with the NO donor S-nitroso-N-acetyl-pencillamine and the antioxidant N-acetyl-cysteine. The NO synthase inhibitors Nomega-nitro-l-arginine-methyl-esther and Nomega-nitro-l-arginine completely abolished the morphine-induced attenuation of NF-kappaB nuclear binding, demonstrating that the inhibitory action is mediated by NO release. CONCLUSION: Morphine causes immunosuppression, at least in part, via the NO-stimulated depression of NF-kappaB nuclear binding.

Acetylcysteine↗

PubMed2000

Antagonism of LPS and IFN-gamma induced iNOS expression in human atrial endothelia by morphine, anandamide, and estrogen.

AIM: To determine whether inducible nitric oxide synthase (iNOS) stimulation of human atrial fragments can be diminished by the naturally occurring signal molecules, such as morphine, anandamide, and estrogen. The use of iNOS as an indicator is justified since it has been associated with initiation of various types of cellular damage either directly or indirectly. METHODS: Western blots were performed on control and drug-exposed atrial tissue before and after lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) exposure. RESULTS: Preincubation of the tissue with morphine, anandamide or estrogen prior to, but not after, the addition of LPS + IFN-gamma, blocked iNOS expression. The nitric oxide donor SNAP also blocked iNOS induction while preincubation of atrial fragments with an inhibitor of NOS, L-NAME, prior to morphine or anandamide exposure, restored LPS + IFN-gamma induction of iNOS. CONCLUSION: These data suggest a direct regulatory link at the transcriptional level between constitutive (c) NOS and iNOS in human atrial tissue.

Adjuvants, Immunologic↗