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Biomedical subjects

A H Mulder

Publications and source records attributed to A H Mulder.

At least 91 records · Page 5Linked to original sources
PubMed1993

Opioid receptor-mediated inhibition of evoked catecholamine release from cultured neurons of rat ventral mesencephalon and locus coeruleus.

The effects of selective opioid agonists on the evoked release of [3H]dopamine and [3H]noradrenaline were studied in cultured dopaminergic neurons of the ventral mesencephalon (containing the substantia nigra and ventral tegmental area) and in cultured neurons of the noradrenergic locus coeruleus, respectively. The cultures were prepared from embryonic day 15 rat brains. After 9 days in culture, the calcium-dependent release of [3H]dopamine from dopaminergic substantia nigra/ventral tegmental area neurons induced by 23 mM k+ appeared to be inhibited exclusively by activation of kappa-opioid receptors, as [3H]dopamine release was inhibited selectively by the kappa agonists U69,593 and dynorphin-(1-13) (EC50 8 and 5 nM, respectively), and this inhibitory effect was antagonized by the kappa-selective antagonist nor-binaltorphimine (Ki 0.07 nM). In contrast, cultured noradrenergic locus coeruleus neurons appeared to contain release-inhibitory mu-opioid receptors only, as evoked [3H]noradrenaline release was inhibited selectively by the mu agonist [D-Ala2, MePhe4, Gly-ol5]enkephalin (EC50 45 nM), a response that was antagonized by the preferential mu antagonist naloxone (Ki = 0.7 nM). The delta-opioid receptor agonist [D-Ser2(O-butyl), Leu5]enkephalyl-Thr6 did not affect catecholamine release. Dopamine release from cultured ventral mesencephalic neurons, induced by 100 microM N-Methyl-D-Aspartate (NMDA), also appeared to be subject to kappa receptor-mediated inhibition, whereas NMDA-induced noradrenaline release from cultured locus coeruleus neurons was under the inhibitor control of mu receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Antineutrophil cytoplasmic antibodies in rheumatoid arthritis. Characterization and clinical correlations.

OBJECTIVE: To study the prevalence, interrelationships, and target antigens of antineutrophil cytoplasmic antibodies (ANCA) in rheumatoid arthritis (RA) and to relate their presence to disease duration and to the occurrence of extraarticular manifestations, including vasculitis. METHODS: Sera from 94 patients with RA (31 with recent-onset disease, 35 with longstanding disease but without extraarticular manifestations, and 28 with extraarticular disease) were studied for the presence of ANCA by indirect immunofluorescence. All sera were tested by enzyme-linked immunosorbent assay (ELISA) for the presence of antibodies to proteinase 3, myeloperoxidase (MPO), elastase, lactoferrin (LF), and cathepsin G (CG), and by Western blotting for antibodies to neutrophil proteins. RESULTS: Seventy percent of the 94 sera showed staining of the nuclei of ethanol-fixed neutrophils; 32% of the 94 were proven to have ANCA, as manifested by their cytoplasmic staining pattern on paraformaldehyde-fixed neutrophils. In the ELISA, 19 sera reacted with LF, 1 with MPO, and 1 with CG. By Western blotting, 21 sera reacted with LF, and 15 reacted with previously unknown polypeptides (7 sera with a 67/66-kd doublet and 8 with a 63/54-kd doublet). Neither of these antibodies was associated with a particular subset of the disease, but the prevalence of the antibodies tended to increase among patients with longstanding disease. CONCLUSION: ANCA in RA patients are directed toward diverse cytoplasmic antigens of the neutrophil, in particular, LF and other, not yet fully characterized polypeptides. The antibodies are not a marker for a disease subset, but are probably a corollary of chronic inflammation.

Adolescent↗
PubMed1993

Antineutrophil antibodies in inflammatory bowel disease recognize different antigens.

Anti-neutrophil cytoplasmic antibodies (ANCA) were observed in 31 out of 68 sera (45%) from Ulcerative Colitis (UC) patients and in 13 out of 38 Crohn's Disease (CD) sera (34%). The presence of ANCA was not related to disease activity, nor to the localization of the disease manifestations. By Western Blotting ANCA showed reactivity with either lactoferrin, polypeptides occurring as a doublet of 66/67 kD MW, or polypeptides occurring as a doublet of 63/54 kD MW.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1993

Anti-neutrophil cytoplasmic antibodies (ANCA) in autoimmune liver disease.

ANCA were detected in 67% of sera from patients with primary sclerosing cholangitis (n = 15), in 83% of sera from patients with autoimmune chronic active hepatitis (n = 18) and in 35% of sera from patients with primary biliary cirrhosis (n = 20). ANCA were not detected in non-autoimmune chronic liver diseases. Characterization studies of the antigens involved showed that ANCA in autoimmune liver disease are not directed against myeloperoxidase (mpo), proteinase 3 (pr3) or elastase (hle), but the ANCA in autoimmune liver disease show reactivity with lactoferrin, a 67/66 kD protein combination or a 63/54 kD protein combination on Western Blots.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1993

Chronic exposure to morphine and naltrexone induces changes in catecholaminergic neurotransmission in rat brain without altering mu-opioid receptor sensitivity.

In order to investigate the role of mu-opioid receptor regulation in catecholaminergic neurotransmission during morphine tolerance/dependence and supersensitivity, we measured changes in number and functional properties of two distinct types of mu receptors in the brain of rats chronically treated with morphine and naltrexone. In membranes of striatum and cortex of morphine treated rats the binding of mu ligand [3H]DAMGO was unaltered, whereas an increase in mu binding sites was found in these brain regions of naltrexone treated rats. The ability of the mu agonist DAMGO to inhibit the dopamine D-1 receptor stimulated cAMP production in striatal slices and the electrically evoked release of [3H]noradrenaline from cortical slices was unaffected in both experimental groups. The major changes found were an increased D-1 receptor stimulated cAMP production and an enhanced release of noradrenaline in morphine treated rats and a decreased D-1 receptor stimulated cAMP production in naltrexone treated rats. These data support the hypothesis that tolerance and supersensitivity to morphine and other mu-opioids may be caused by up- and down-regulated neuronal second messenger systems linked to mu-opioid receptors, rather than by changes in the sensitivity of the mu-opioid receptor itself.

Adenylyl Cyclases↗
PubMed1993

Neutrophil cytoplasmic autoantibodies after liver transplantation in patients with primary sclerosing cholangitis.

The immunopathogenic importance of neutrophil cytoplasmic autoantibodies in ulcerative colitis and primary sclerosing cholangitis is unknown. These autoantibodies were investigated before and after liver transplantation in 9 patients with primary sclerosing cholangitis. Sera from 10 patients transplanted for metabolic disorders or hemangioma served as controls. Before liver transplantation neutrophil cytoplasmic autoantibodies, producing a perinuclear pattern by indirect immunofluorescence on ethanol fixed neutrophils, were present in all patients with primary sclerosing cholangitis. A decline in titer was noted in the first months after liver transplantation. During long-term follow up, the autoantibodies remained present and most often the titer did not differ from before transplantation. They were not directed against proteinase 3, myeloperoxidase, elastase or lactoferrin. All but one of the control patients were negative for the autoantibody. No relation was seen, before or after transplantation, with ulcerative colitis or proctocolectomy. There was no recurrence of primary sclerosing cholangitis in any of the patients as judged by liver histology. We conclude that neutrophil cytoplasmic autoantibodies remain present after liver transplantation for primary sclerosing cholangitis and that its synthesis is not related to the presence of the diseased organ(s). The primary disease process in primary sclerosing cholangitis and ulcerative colitis may well be a disturbance of the immune system.

Adult↗
PubMed1993

Assessment of response of esophageal carcinoma to induction chemotherapy.

Endoscopic ultrasonography (EUS) is currently considered the best available technique for the local staging of esophageal cancer. In a prospective study 11 patients with esophageal squamous cell carcinoma were investigated to evaluate the usefulness of EUS in the assessment of response to induction chemotherapy. Response to chemotherapy was evaluated by means of history of dysphagia, endoscopy, computed tomography (CT) and EUS to assess relief of clinical symptoms, reduction of tumor bulk and depth of tumor invasion (T-stage). One patient was excluded because EUS failed. Tumor response was best correlated with relief of dysphagia and by tumor bulk reduction as determined on endoscopy and CT. We found it not useful to measure reduction of tumor bulk with EUS because of tumor compression by the instrument, stenosis, or the hypoechoic thickening of the esophageal wall caused by an inflammatory reaction after chemotherapy. There was no change in EUS T-staging after induction chemotherapy compared to prechemotherapy assessment. EUS T-staging after induction chemotherapy was accurate in 6 of 10 patients compared to the histopathologic examination of the resected specimen. There was EUS T3-overstaging in 4 patients, caused by partial or complete replacement of the tumor by an inflammatory reaction due to chemotherapy. We conclude that inflammatory changes induced by chemotherapy lead to EUS overstaging of the T stage thus making it a less reliable tool in restaging after chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Somatostatin analogue scintigraphy of malignant lymphomas.

Normal as well as activated lymphocytes, macrophages and leukaemic cells have previously been shown by radio receptor analysis to express receptors for somatostatin. An 111In labelled somatostatin analogue was already used successfully in the visualization of a variety of neuro-endocrine tumours. We investigated 10 consecutive patients with malignant lymphomas (Hodgkin's disease and non-Hodgkin's lymphomas). In all patients the lymphoma deposits could be visualized with somatostatin receptor imaging. In four patients additional tumour localizations were observed as compared to the results of combined physical and radiological (CT and ultrasound) examinations. In four cases tissue biopsies were taken and confirmed by autoradiography to be somatostatin receptor positive. These data indicate that malignant lymphomas may express somatostatin receptors in sufficient numbers and density to allow in vivo tumour visualization with a radiolabelled somatostatin analogue.

Hodgkin Disease↗
PubMed1993

Adrenocorticotropin/alpha-melanocyte-stimulating hormone (ACTH/MSH)-like peptides modulate adenylate cyclase activity in rat brain slices: evidence for an ACTH/MSH receptor-coupled mechanism.

The regulation of adenylate cyclase activity by adrenocorticotropin/alpha-melanocyte-stimulating hormone (ACTH/MSH)-like peptides was investigated in rat brain slices using a superfusion method. Adenylate cyclase activity was concentration-dependently increased by ACTH-(1-24), alpha-MSH (EC50 values 16 and 6 nM, respectively), and [Nle4,D-Phe7]alpha-MSH (EC50 value 1.6 nM), in the presence of forskolin (1 microM, optimal concentration). 1-9-Dideoxyforskolin did not augment the response of adenylate cyclase to ACTH-(1-24). Various peptide fragments were tested for their ability to enhance [3H]cyclic AMP production. [Nle4,D-Phe7]alpha-MSH increased [3H]cyclic AMP formation with a maximal effect of 30% and was more potent than ACTH-(1-24), ACTH-(1-16)-NH2, alpha-MSH, ACTH-(1-13)-NH2, [MetO4]alpha-MSH, [MetO2(4),D-Lys8,Phe9]ACTH-(4-9), ACTH-(7-16)-NH2, ACTH-(1-10), and ACTH-(11-24), in order of potency. This structure-activity relationship resembles that found for the previously described peptide-induced display of excessive grooming. ACTH-(1-24) stimulated adenylate cyclase activity in both striatal (maximal effect, approximately 20%) and septal slices (maximal effect, approximately 40%), but not in hippocampal or cortical slices. Lesioning of the dopaminergic projections to the striatum did not result in a diminished effect of [Nle4,D-Phe7]alpha-MSH on [3H]cyclic AMP accumulation, which indicates that the ACTH/MSH receptor-stimulated adenylate cyclase is not located on striatal dopaminergic terminals. ACTH-(1-24) did not affect the dopamine D1 or D2 receptor-mediated modulation of adenylate cyclase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1993

Interacting presynaptic kappa-opioid and GABAA receptors modulate dopamine release from rat striatal synaptosomes.

The presynaptic regulation of stimulated dopamine release from superfused rat striatal synaptosomes by opioids and gamma-aminobutyric acid (GABA) was studied. It was found that in addition to dopamine D2 autoreceptors, calcium-dependent K(+)-stimulated [3H]dopamine release was inhibited through activation of a homogeneous population of kappa-opioid receptors in view of the potent inhibitory effect of the kappa-selective agonist U69,593 (EC50 0.2 nM) and its antagonism by norbinaltorphimine. Neither mu- nor delta-selective receptor agonists affected release of [3H]-dopamine. In addition, GABA potently inhibited the evoked [3H]dopamine release (EC50 0.4 nM) through activation of GABAA receptors in view of the GABA-mimicking effect of muscimol, the sensitivity of its inhibitory effect to picrotoxin and bicuculline, and the absence of an effect of the GABAB receptor agonist baclofen. In the presence of a maximally effective concentration of GABA, U69,593 did not induce an additional release-inhibitory effect, indicating that these receptors and the presynaptic D2 receptor are colocalized on the striatal dopaminergic nerve terminals. The excitatory amino acid agonists N-methyl-D-aspartate and kainate, as well as the cholinergic agonist carbachol, stimulated [3H]dopamine release, which was subject to kappa-opioid receptor-mediated inhibition. In conclusion, striatal dopamine release is under regulatory control of multiple excitatory and inhibitory neurotransmitter by activation of colocalized presynaptic receptors for excitatory amino acids, acetylcholine, dopamine, dynorphins, and GABA within the dopaminergic nerve terminals. Together, these receptors locally control ongoing dopamine neurotransmission.

Analysis of Variance↗
PubMed1993

In vivo somatostatin receptor imaging in medullary thyroid carcinoma.

Using in vivo scintigraphy with the 111In-labeled somatostatin analog octreotide, tumor localizations were demonstrated in 11 of 17 patients (65%) with medullary thyroid carcinoma (MTC). Tumor localizations in the liver in 7 patients, and in the thyroid in 1 patient were not detected on octreotide scintigraphy, most probably because of normal uptake of labeled octreotide in these organs. Specific somatostatin receptors were demonstrated in vitro on all 5 investigated tumors which had also been visualized in vivo, as well as on 1 tumor that was not. Immunohistochemically, somatostatin was present in 1 of 6 tumors that were visualized in vivo, and in neither of 2 tumors that were not. The ratio of serum calcitonin over carcino-embryonic antigen concentrations was significantly higher in patients whose MTCs were visualized during octreotide scintigraphy than in those whose tumors were not. We have formed the following conclusions: 1) In the majority of patients with metastatic MTC, tumor sites can be visualized using octreotide scintigraphy, although this technique is insensitive in detecting liver metastases or intrathyroidal tumor; 2) The visualization of MTC during in vivo somatostatin receptor imaging correlates with the in vitro presence of somatostatin receptors; 3) The immunohistochemical presence of somatostatin in the tumor does not seem to influence the outcome of in vivo somatostatin receptor imaging; and 4) Higher serum calcitonin over carcino-embryonic antigen ratios in patients whose MTC is visualized during octreotide scintigraphy might imply that somatostatin receptors are present on more differentiated MTC.

Adult↗
PubMed1993

Transient neurologic and ocular manifestations in primary thrombocythemia.

We report the presenting neurologic and visual symptoms in 17 patients with primary thrombocythemia. Poorly localizing symptoms occurred in 14 patients: transient unsteadiness in 13, dysarthria in eight, and scintillating scotomata in four. Nine patients had focal symptoms: transient monocular blindness in two patients, transient mono- or hemiparesis in six, and both of these in one patient. The attacks all had a sudden onset, occurred sequentially rather than simultaneously, lasted for a few seconds to several minutes, and were usually associated with a dull or pulsatile headache. A causal platelet-mediated arterial thrombosis was evident in 15 patients. There were no recurrences of thrombotic or ischemic events during long-term treatment of 12 patients with aspirin and during cytostatic reduction of platelet count to normal in seven patients. We conclude that low-dose aspirin and reduction of platelet count to normal are effective, but coumarin is ineffective, in the treatment and prevention of arterial thrombosis in thrombocythemia.

Adult↗
PubMed1993

Mu- and delta-opioid receptors inhibitorily linked to dopamine-sensitive adenylate cyclase in rat striatum display a selectivity profile toward endogenous opioid peptides different from that of presynaptic mu, delta and kappa receptors.

The apparent affinities of endogenous opioid peptides for noncompetitively interacting mu and delta receptors, inhibitorily linked to dopamine (DA) D-1 receptor-stimulated adenylate cyclase, were investigated in superfused rat striatal slices exposed to 40 microM DA in the presence of 10 microM of the selective D-2 receptor antagonist (-)sulpiride. In the presence of peptidase inhibitors, a comparison was made with the apparent affinities of opioid peptides toward independent presynaptic opioid receptors in brain slices. beta-Endorphin had an about 100-fold higher apparent affinity (EC50: 1 nM) toward presynaptic mu-opioid receptors, mediating inhibition of the electrically evoked neocortical [3H]norepinephrine release, than for the striatal adenylate cyclase-coupled mu receptors. In contrast, the kappa-opioid receptor agonist dynorphin A1-13 displayed a similar apparent affinity (EC50: 0.1 microM) toward these functionally different mu receptors. Both Leu- and Met-enkephalin showed only a 3-fold higher apparent affinity (EC50: 30 nM) for presynaptic delta-opioid receptors, mediating inhibition of striatal [14C]acetylcholine release, than for presynaptic mu receptors. However, whereas Leu-enkephalin had a similar apparent affinity for presynaptic and adenylate cyclase-coupled delta receptors, Met-enkephalin displayed a 30-fold selectivity toward the latter receptors. Studying the inhibitory effect of Met-enkephalin on striatal adenylate cyclase stimulated by endogenously released (amphetamine-induced) DA, its very high affinity appeared to be inversely related to the activation of inhibitory DA D-2 receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1993

Acute side effects of homologous interleukin-3 in rhesus monkeys.

Interleukin-3 treatment of juvenile rhesus monkeys elicits a dose- and time-dependent syndrome that includes urticaria, palpable lymph nodes, splenomegaly, thrombocytopenia, anemia, vomiting, diarrhea, intestinal bleeding, edema, and arthritis, apart from a strong stimulation of hemopoiesis. Arthritis was found to occur significantly more often in animals expressing the major histocompatibility complex alleles B9 and Dr5. Histological analysis revealed an abundance of mast cells in urticaria and, to a lesser extent, in lungs and synovia of arthritic joints. Active osteoclasts were abundant in ribs and arthritic joints. Extramedullary hemopoiesis was encountered in liver, spleen, and kidneys. The spleen showed deposits of hemosiderin, and in the liver, Kupffer cells were loaded with iron, indicating enhanced turnover of hemoglobin. Lymph nodes and bone marrow showed macrophages involved in hemophagocytosis, which probably contributed to the development of anemia and thrombopenia. Biochemical parameters in sera were indicative of parenchymal liver damage, with cholestasis and increased erythrocyte destruction. The side effects were strongly reduced in monkeys subjected to total body irradiation just before interleukin-3 treatment. Histamine antagonists were not significantly effective in preventing side effects, which is explained by the perpetual stimulation of basophilic granulocytes by exogenous interleukin-3. The nature of the side effects indicates that interleukin-3 may be involved in the pathogenesis of acute type hypersensitivity reactions and arthritis.

Anemia↗
PubMed1993

Prevalence and characterization of neutrophil cytoplasmic antibodies in autoimmune liver diseases.

To evaluate the diagnostic significance of neutrophil cytoplasmic antibodies in chronic liver diseases, we assessed the prevalence of neutrophil cytoplasmic antibodies in autoimmune liver diseases, in particular in primary sclerosing cholangitis, autoimmune chronic active hepatitis and primary biliary cirrhosis, and we also determined the specificity of perinuclear-pattern neutrophil cytoplasmic antibodies for these autoimmune liver diseases by testing sera from patients with nonautoimmune chronic liver diseases. Neutrophil cytoplasmic antibodies were detected in 79% of sera from patients with primary sclerosing cholangitis (n = 24), in 88% of sera from patients with autoimmune chronic active hepatitis (n = 24) and in 28% of sera from patients with primary biliary cirrhosis (n = 25). The presence of neutrophil cytoplasmic antibodies in these diseases correlated significantly (p < 0.008) with the presence of cirrhosis. Neutrophil cytoplasmic antibodies were not detected in nonautoimmune liver diseases. All neutrophil cytoplasmic antibody-positive sera produced a perinuclear fluorescence pattern on ethanol-fixed granulocytes. On neutrophils fixed with paraformaldehyde, a granular cytoplasmic immunofluorescence pattern was observed, demonstrating the cytoplasmic nature of the antigen or antigens involved. Further characterization studies showed that neutrophil cytoplasmic antibodies in autoimmune liver diseases are not directed against myeloperoxidase, proteinase 3 or elastase, the neutrophil cytoplasmic antibody specificities associated with necrotizing vasculitis, glomerulonephritis or both. On Western blots neutrophil cytoplasmic antibodies in autoimmune liver diseases showed reactivity with either lactoferrin, a 67/66-kD protein combination or a 40-kD polypeptide. Reactivity with either of these proteins was observed in sera from patients with primary sclerosing cholangitis (38%), autoimmune chronic active hepatitis (17%) and primary biliary cirrhosis (20%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Opioid receptors and inhibition of dopamine-sensitive adenylate cyclase in slices of rat brain regions receiving a dense dopaminergic input.

In slices of rat nucleus accumbens, olfactory tubercle, frontal cortex and mediobasal hypothalamus exposed to dopamine (DA), the activation of DA D1 receptors stimulated cyclic AMP (cAMP) formation whereas, in nucleus accumbens slices only, activation of D2 receptors appeared to inhibit D1 receptor-stimulated adenylate cyclase at the same time. Activation of mu-opioid receptors by [D-Ala2,MePhe4,Gly-ol5]enkephalin (DAMGO; 1 microM), but not of delta-opioid receptors by 1 microM [D-Pen2,D-Pen5]enkephalin (DPDPE), inhibited (by 35-40%) DA-stimulated cAMP production in slices of nucleus accumbens and olfactory tubercle. When adenylate cyclase was stimulated by selective D1 receptor activation, i.e. by DA in the presence of (-)-sulpiride, DPDPE reduced cAMP formation (by about 45%) in nucleus accumbens slices but not in slices of the other brain regions. The kappa-agonist, U 50,488, did not affect DA- or D1 receptor-stimulated adenylate cyclase activity in any of the brain regions. Preincubation of nucleus accumbens slices with the irreversible delta-ligand, fentanyl isothiocyanate (FIT; 1 microM), not only antagonized the inhibitory effect of DPDPE but also prevented the antagonism by naloxone of the inhibitory effect of DAMGO. Therefore, in nucleus accumbens opioids may inhibit DA-sensitive adenylate cyclase through activation of a mu/delta-opioid receptor complex, whereas in olfactory tubercle mu-receptors appear to mediate the inhibition of adenylate cyclase activity. Opioids do not seem to affect DA-stimulated cAMP formation in frontal cortex and mediobasal hypothalamus.

Adenylyl Cyclase Inhibitors↗