Immunological characterization of a mucin-associated protein from hamster tracheal epithelial cell culture

Airway mucins are high molecular mass (>10(6) dalton) glycoproteins with various types of associated molecules including glycoproteins, lipoproteins, and lipids. The study of mucin-associated proteins is limited largely due to the lack of specific probes. In this study, we produced a monoclonal antibody, MAbHT10, against a 190-kDa mucin associated-protein by immunizing mice with hamster airway mucin purified in nondissociative condition. Using HT10, the 190-kDa mucin-associated protein was characterized immunologically. The 190-kDa mucin-associated protein is glycoprotein and HT10 recognized carbohydrate containing portion of the protein. The association of 190-kDa protein with mucin is strong enough that heat and detergent treatment is required to dissociate it from mucin as evidenced by gel filtration chromatography, Western blot, enzyme-linked immunoadsorbent assay (ELISA), and co-immunoprecipitation. The expression of the 190-kDa protein is increased with the development of hamster tracheal epithelial cells in culture, but showed differences with the pattern of the regulation of mucin expression. Adenosine triphosphate (ATP), a known strong mucin secretagogue, dose-dependently increased mucin release but caused only marginal increase in the release of the 190-kDa protein. The MAb should be useful in the structural and functional analysis of the 190-kDa mucin-associated proteins in physiological and pathological situations such as chronic airway diseases.

Region specific increase of dopamine receptor D1/D2 mRNA expression in the brain of mu-opioid receptor knockout mice

Previous pharmacological studies have indicated the possible existence of functional interactions between opioidergic and dopaminergic neurons in the CNS. In this study, the expression of mRNAs encoding dopamine receptor D1/D2 was examined to investigate whether there is a change in the dopamine pathway of mice lacking the mu-opioid receptor by in situ hybridization technique. In the mu-opioid receptor knockout mice, the expression of dopamine receptor D1 mRNA was increased in the olfactory tubercle, nucleus accumbens, caudate putamen, and the layer VI of the neocortex compared with that of wild-type mice. The expression of dopamine receptor D2 mRNA was also increased in the olfactory tubercle, caudate putamen, and the nucleus accumbens of mu-opioid receptor knockout mice. These results indicate that there are compensational changes in the dopaminergic systems of mu-opioid receptor knockout mice.

Effects of morphine on pentobarbital-induced responses in mu-opioid receptor knockout mice

Effects of morphine on the potentiation of pentobarbital-induced responses were investigated using mu-opioid receptor knockout mice. The duration of loss of righting reflex, hypothermia, and loss of motor coordination induced by pentobarbital were measured after pretreatment with either morphine or saline. Morphine pretreatment failed to show potentiation of both pentobarbital-induced loss of righting reflex and hypothermia in mu-opioid receptor knockout mice, while it significantly potentiated these responses in the wild-type controls. For motor incoordination test, morphine potentiated pentobarbital-induced motor incoordination in the wild-type mice. However, morphine may have opposite effects in the mu-opioid receptor knockout mice. These results demonstrate that synergism between morphine and pentobarbital is not detected in mu-opioid receptor knockout mice and that potentiation of pentobarbital-induced loss of righting reflex and hypothermia by morphine is mediated through mu-opioid receptor. It was interesting to note that pentobarbital-induced decrease in body temperature was less severe in mu-opioid receptor knockout mice than in wild-type mice.

ATP-induced mucin release from cultured airway goblet cell involves, in part, activation of phospholipase A2

Adenosine triphosphate (ATP) has been shown to stimulate mucin release by activation of protein kinase C (PKC) following activation of phospholipase C (PLC) coupled to the P2 receptor via G-proteins. The aim of the present study was to investigate pathways downstream to the PKC activation in ATP-induced mucin release from primary hamster tracheal surface epithelial (HTSE) cells. The release of mucin was determined by chromatographic procedure after metabolic labeling of mucin with [3H]-glucosamine. The results were: i) ATP induced the release of arachidonic acid, which caused the release of mucin. Pretreatment with mepacrine (0.3 mM), a phospholipase A2 (PLA2) inhibitor, inhibited the ATP-induced arachidonic acid and mucin release. Oleoyloxyethylphosphocholine, another PLA2 inhibitor, gave similar results. ii) An activator of PKC, 4 beta-phorbol-12 alpha-myristate-13-acetate (PMA, 1 microM) induced mucin release, which was inhibited by mepacrine pretreatment. iii) Downregulation of PKC by prolonged (16 h) PMA treatment caused inhibition of ATP-induced mucin release. Treatment of PKC downregulated HTSE cells with mepacrine did not further decrease the ATP-induced mucin release. These results suggest that PLA2 is involved in ATP-induced mucin release and its activation is sequential to the PLC-PKC pathway.

Augmented death in immunostimulated astrocytes deprived of glucose: inhibition by an iron porphyrin FeTMPyP

The present study shows that under glucose-deprived conditions immunostimulated astrocytes rapidly undergo death due to their increased susceptibility to endogenously produced peroxynitrite. Fe(III)tetrakis(N-methyl-4'-pyridyl)porphyrin (FeTMPyP), but not the structurally related compounds ZnTMPyP and H(2)TMPyP, prevented the death in glucose-deprived immunostimulated astrocytes. Consistently, FeTMPyP, not ZnTMPyP and H(2)TMPyP, completely blocked the elevation of nitrotyrosine immunoreactivity (a marker of peroxynitrite) and the depolarization of the mitochondrial transmembrane potential in glucose-deprived immunostimulated astrocytes. The present data suggest that peroxynitrite may be associated with glial cell death during metabolic deterioration in the cerebral ischemic penumbra.

Effect of repeated seizure experiences on tyrosine hydroxylase immunoreactivities in the brain of genetically epilepsy-prone rats

The genetically epilepsy-prone rat (GEPR) is a model of generalized tonic/clonic epilepsy, and has functional noradrenergic deficiencies that act as partial determinants for the seizure predisposition and expression. The present study investigated the effect of repeated seizure experiences by acoustic stimulation (110 dB, 10 times) on the immunoreactivities of tyrosine hydroxylase (TH), a rate-determining enzyme in the synthesis of norepinephrine, in brain regions of GEPRs. TH immunoreactivity in locus coeruleus, the major noradrenergic nucleus in brain, was lower in GEPRs than control Sprague-Dawley rats. It was also decreased in several regions including inferior colliculus of GEPRs. Repeated experiences of audiogenic seizures further decreased TH immunoreactivities in locus coeruleus and inferior colliculus of GEPRs. The results from the present study suggest that the lower immunoreactivities of TH in locus coeruleus and inferior colliculus contribute, at least in part, to the noradrenergic deficits in GEPRs, and repeated seizure experiences further intensified these noradrenergic deficits, which may be related to the altered seizure expression by repetitive audiogenic seizure in GEPRs.

Cross-species immunoreactivity of airway mucin as revealed by monoclonal antibodies directed against mucins from human, hamster, and rat

Airway mucin plays crucial role in host-defense and has been implicated in pathophysiology of various airway diseases including asthma and cystic fibrosis. The analysis of airway mucin has been hampered mostly by the lack of specific and efficient methods for the detection of mucin. Recent production of antibodies against airway mucin from several species and also the development of immunoassay procedures make it more efficient to study the airway mucin. However, the cross-species immunoreactivity of antibodies against airway mucin has not been clearly demonstrated and this prompted us to investigate the cross-species immunoreactivity of monoclonal antibodies against human (HM02), hamster (HTA), and rat airway mucin (RT03), which is three most widely used species in the study of mucin. All the monoclonal antibodies (MAbs) used in this study is IgM isotype and recognizes N-acetyl-galactosamine-linked carbohydrate core or backbone portion of airway mucin. In enzyme-linked immunoadsorbent assay (ELISA), Western blot, immunoprecipitation, and immunohistochemical staining experiments, it was demonstrated that human and hamster airway mucin showed strong cross-species immunoreactivity. However, rat airway mucin did not show any cross-species immunoreactivity against human and hamster airway mucin. Endotoxin-induced secretory cell metaplasia and hence the increase in mucin release from hamster airway mucin could be detected with antibodies against hamster and human airway mucin in vivo and in vitro. However, the same increase from rat airway could only be detected with antibody against rat airway mucin but not with antibodies against human and hamster airway mucin. In addition, the increase in mucin release from asthmatic patients could be detected with antibodies against human and hamster airway mucin but not with the antibody against rat airway mucin. The data from the present study implicates that the carbohydrate chain of human and hamster airway mucin, but not that of rat airway mucin, share common antigenic structure. In case of the interspecies use of the antibodies against airway mucin, it would be more desirable to clearly identify the cross-species immunoreactivity otherwise might lead to erroneous results.

Phenidone prevents kainate-induced neurotoxicity via antioxidant mechanisms

Acculmulating evidence indicates that a marked generation of oxygen free radicals derived from the metabolism of arachidonic acid causes neurodegeneration. Recently, we have demonstrated that the novel antioxidant actions mediated by phenidone, a dual inhibitor of cyclooxygenase/lipoxygenase pathways, may play a crucial role in preventing neuroexcitotoxicity in vitro [Neurosci. Lett. 272 (1999) 91], and that phenidone significantly attenuates kainic acid (KA)-induced seizures via inhibiting the synthesis of Fos-related antigen protein [Brain Res. 782 (1998) 337]. In order to extend our understanding of the pharmacological intervention of phenidone, we evaluated the antioxidant activity of this compound in vivo in the present study. In order to better understand the significance of a blockade of both the cyclooxygenase and lipoxygenase pathways, we studied the effects of aspirin (ASP; a non-selective inhibitor of cyclooxygenase), NS-398 (a selective inhibitor of cyclooxygenase-2), esculetin (an inhibitor of lipoxygenase) and phenidone on lipid peroxidation, protein oxidation, and glutathione (GSH) status in the rat hippocampus after KA administration. ASP (7.5 or 15 mg/kg), NS-398 (10 or 20 mg/kg), esculetin (5 or 10 mg/kg) or phenidone (25, 50 or 100 mg/kg) was administered orally five times every 12 h before the injection of KA (10 mg/kg, i.p.). The KA-induced toxic behavioral signs, oxidative stress (lipid peroxidation and protein oxidation), impairment of GSH status, and the loss of hippocampal neurons were dose-dependently attenuated by the phenidone, NS-398+esculetin, and ASP+esculetin. However, ASP, NS-398 and esculetin alone failed to protect against the neurotoxicities induced by KA. Therefore, the results suggest that protection by blockade of both cyclooxygenase and lipoxygenase pathways against KA-induced neuroexcitotoxicity is via antioxidant actions. However, a novel anticonvulsant/neuroprotective effect mediated by phenidone remains to be further characterized.

Protection by a manganese porphyrin of endogenous peroxynitrite-induced death of glial cells via inhibition of mitochondrial transmembrane potential decrease

In the cerebral ischemic penumbra, progressive metabolic deterioration eventually leads to death of glial cells. The exact mechanism for the death of glial cells is unclear. Here we report that under glucose-deprived conditions immunostimulated glial cells rapidly underwent death via production of large amounts of peroxynitrite. The cell-permeable Mn(III)tetrakis(N-methyl-4'-pyridyl)porphyrin (MnTMPyP) caused a concentration-dependent attenuation of the increased death in glucose-deprived immunostimulated glial cells. The structurally related compound H(2)TMPyP, which lacks metals, did not attenuate this augmented cell death. MnTMPyP prevented the elevation in nitrotyrosine immunoreactivity (a marker of ONOO(-)) in glucose-deprived immunostimulated glial cells. In glucose-deprived glial cells, MnTMPyP also completely blocked the augmented death and nitrotyrosine immunoreactivity induced by the ONOO(-)-producing reagent 3-morpholinosydnonimine (SIN-1). The mitochondrial transmembrane potential (MTP), as measured using the dye JC-1, was rapidly decreased in immunostimulated or SIN-1-treated glial cells deprived of glucose. MnTMPyP, but not H(2)TMPyP, blocked the depolarization of MTP in those glial cells. The present data, at least in part, provide evidence for how glial cells die in the postischemic and/or recurrent ischemic brain.

Role of signals from the dorsal root ganglion in neuropathic pain in a rat model

We examined whether signals from the neuroma or the dorsal root ganglion of the injured segment are critical for the generation of neuropathic pain. To this aim, we used a rat model of peripheral neuropathy made by transecting the inferior and superior caudal trunks at the level between the S1 and S2 spinal nerves under enflurane anesthesia. These animals displayed tail-withdrawal responses to normally innocuous mechanical stimulation applied to the tail with a von Frey hair (2 g). Also, these animals, compared to pre-surgical value, displayed shorter tail-withdrawal latencies following immersion of the tail to warm (40 degrees C) or cold (4 degrees C) water. Transection of the S1 spinal nerve between the dorsal root ganglion and neuroma did not change the behavioral signs of neuropathic pain. In contrast, S1 dorsal rhizotomy significantly reduced the behavioral signs. The data suggest that signals arising from the dorsal root ganglion cells of the injured segment, but not from the neuroma, are critical for the generation of neuropathic pain in this model.

A case of Cushing's syndrome in ACTH-secreting mediastinal paraganglioma

Paragangliomas are unusual neuroendocrine cell tumors arising from paraganglia, of which ACTH-secreting cases in the mediastinum are extremely rare. A 51-year-old woman was admitted for generalized edema and weakness which began 5 months ago. Chest X-ray and CT scan revealed a tumor mass in the anterior mediastinum. The plasma cortisol and ACTH levels were very high. Other sources secreting ACTH, except mediastinal mass, were not found. Surgical excision of mediastinal mass and left supraclavicular lymph node was performed. The postoperative microscopic finding and immunohistochemical staining revealed organoid tumor cell nests (zellballen) and S-100 protein positive sustentacular cells which are characteristics of paraganglioma. This was thus a case of Cushing's syndrome resulting from ectopic ACTH production in anterior mediastinal paraganglioma.

Comparison of G-protein activation in the brain by mu-, delta-, and kappa-opioid receptor agonists in mu-opioid receptor knockout mice

Mice lacking the mu-opioid receptor gene have been developed by a gene knockout procedure. In this study, the activity of opioid receptor coupled G-proteins was examined to investigate whether there is a change in the extent of coupling for mu, delta-, and kappa-opioid receptors in mu-opioid receptor knockout mice. Selective agonists of mu- (DAMGO), delta- (DPDPE), and kappa- (U-69,593) opioid receptors stimulated [(35)S]GTPgammaS binding in the caudate putamen and cortex of wild-type mice. In contrast, only U-69,593 stimulated [(35)S]GTPgammaS binding in these regions of mu-opioid receptor knockout mice. These results confirmed the absence of G-protein activation by a mu-opioid receptor agonist in mu-opioid receptor knockout mice, and demonstrated that coupling of the kappa-opioid receptor to G-proteins is preserved in these mice. However, G-protein activation by the delta-opioid receptor agonist, DPDPE, was reduced in the mu-opioid receptor knockout mice, at least in the brain regions studied using autoradiography.

Pleural empyema due to Salmonella: a case report

Pleuropulmonary involvement of salmonella infection is very rare and only two cases of salmonella empyema have been reported in Korea. We report the case of a 70-year-old female diabetic patient who presented with right flank pain and right lower chest pain. The chest radiographs revealed fibrostreaky and hazy density at right lower lung field and blunting of right costophrenic angle. Thoracentesis revealed turbid yellowish fluid. Salmonella group B was identified from the cultures of blood and pleural fluid. After antimicrobial therapy and repeated therapeutic thoracentesis, the patient was improved.

A comparison of Min's glasses and conventional occlusion therapy in the treatment of amblyopic children: a prospective study

Min's glasses are specially manufactured in order to enhance the satisfaction of the wearer and increase treatment effectiveness. We compared the effectiveness of Min's glasses with that of conventional occlusion therapy in amblyopic pediatric patients. We prospectively studied 60 amblyopic patients. For four to 30 months, 24 of the patients were treated with conventional patch occlusion (patch group) and 36 of them were treated with Min's glasses (glasses group). We compared the improvement in visual acuity and the treatment compliance between both groups, according to age (over six and less than six), sex, type of amblyopia, and the duration of treatment. Sixteen patients (66.7%) in the patch group and 32 patients (88.9%) in glasses group showed improvement in visual acuity (p = 0.002). The pre-treatment average log MAR acuity was 0.56 +/- 0.25 in the patch group, and 0.59 +/- 0.25 in the glasses group. The average improvement in visual acuity was a 0.17 log MAR score in the patch group, and a 0.31 log MAR score in the glasses group (p = 0.004). Compliance was 59.54% in the patch group and 83.44% in the glasses group (p = 0.012). The pre-treatment average log MAR acuity was 0.49 +/- 0.23 for children over six years of age in the patch group, and 0.58 +/- 0.28 for children over six years of age in the glasses group. For children over six years of age in the glasses group the improvement in visual acuity (0.29 log MAR score) was greater than for children over six years of age in the patch group (0.06 log MAR score) (p = 0.0003). The pre-treatment average log MAR acuity was 0.55 +/- 0.22 for female patients in the patch group, and 0.60 +/- 0.25 for female patients in the glasses group. Female patients in the glasses group also showed a greater visual acuity improvement (0.29 log MAR score) than female patients in the patch group (0.14 log MAR score) (p = 0.0028). However, there were no differences between the groups in patients less than six years of age and in male patients. In conclusion, Min's glasses were more effective than conventional treatment with a patch in improving visual acuity and encouraging compliance in pediatric amblyopic patients, especially in children over six years of age and in girls.

Squamous differentiation downregulates Muc1 mucin in hamster tracheal surface epithelial cell

To investigate whether the squamous differentiation of primary hamster tracheal epithelial cell, which is induced by retinoic acid deficiency or chronic PMA treatment, regulates Muc1 expression, we first produced and characterized a monoclonal antibody against hamster tracheal Muc1 mucin using pGEX-Muc1 fusion protein as an antigen and the changes of Muc1 mucin expression was determined by Western blot. Squamous differentiation downregulated the expression of Muc1 mucin from HTSE cells. The decrease in the immunoreactivity of Muc1 mucin was parallel to the decrease in the immunoreactivity of high molecular weight mucin, which is secreted from HTSE cells. The data from the present study implicate a possible role of Muc1 mucin in squamous differentiation of HTSE cells.

Effect of norepinephrine release on adrenoceptors in severe seizure genetically epilepsy-prone rats

The genetically epilepsy-prone rat (GEPR) seizure model is characterized by extensive abnormalities in brain noradrenergic function. Earlier studies had suggested that GEPRs might not regulate adrenoceptors in a normal fashion. The purpose of the present study was to determine if GEPR-9s are capable of up and down regulation of alpha(1)- and beta-adrenoceptors in response to increments or decrements in extracellular norepinephrine. Seizure induction has been shown to increase extracellular norepinephrine. Chronic sound or electroshock-induced seizures caused down regulation of beta-adrenoceptors in frontal cortex and in hippocampus from GEPR-9s. Similarly, chronic daily treatment with the norepinephrine reuptake inhibitor desmethylimipramine produced down regulation of beta-adrenoceptors in frontal cortex and in hippocampus from GEPR-9s. As is the case in neurologically normal animals, chronic electroshock-induced seizure did not cause down regulation of beta-adrenoceptors in 6-hydroxydopamine pretreated GEPR-9s. Chronic electroshock treatment also caused up-regulation of alpha(1)-adrenoceptors in frontal cortex but not in hippocampus. In 6-hydroxydopamine pretreated GEPR-9s, chronic electroshock treatment caused a further up-regulation of alpha(1)-adrenoceptors in frontal cortex but not in hippocampus. Taken together, these results indicate that GEPR-9s are capable of up and down regulation of alpha(1)- and beta-adrenoceptors in a manner that is qualitatively similar to the regulation of these receptors in normal animals. Whether the regulation of brain adrenoceptors is quantitatively different in GEPRs from normal animals remains to be established.

kappa-opioid agonist stimulated regional distribution of [(35)S]GTPgammas binding in butorphanol continuously infused rat

Butorphanol is a mixed agonist/antagonist opioid analgesic agent, which exerts its effects mainly by interaction with the kappa-opioid receptor. Opioid receptors are coupled to G proteins of G(i)/G(o) family, and recently a decrease in micro-opioid activation of G proteins has been reported in specific brainstem nuclei after chronic morphine administration. The influence of centrally administered butorphanol on agonist-stimulated G protein coupling was examined in the rat brain, using in situ guanylyl-5'-O-(gamma-[(35)S]thio)-triphosphate (GTPgammaS) binding autoradiography. Rats were treated with butorphanol (26 nmol/microl/h) by intracerebroventricular infusion via osmotic minipumps for 3 days. The distribution of [(35)S]GTPgammaS binding in the brain 7 h after the termination of butorphanol infusion was measured in the presence or absence of the selective kappa-opioid agonist, U-50,488. This agonist significantly increased [(35)S]GTPgammaS binding in the parietal cortex, caudate putamen, thalamus, and central gray of control rats, but not in those regions of the butorphanol-infused animals. These results suggest that chronic administration of butorphanol developed tolerance and abolished U-50,488 activation of G proteins in these brain areas.

Synergistic depletion of astrocytic glutathione by glucose deprivation and peroxynitrite: correlation with mitochondrial dysfunction and subsequent cell death

Previously we reported that immunostimulated astrocytes were highly vulnerable to glucose deprivation. The augmented death was mimicked by the peroxynitrite (ONOO )-producing reagent 3-morpholinosydnonimine (SIN-1). Here we show that glucose deprivation and ONOO- synergistically deplete intracellular reduced glutathione (GSH) and augment the death of astrocytes via formation of cyclosporin A-sensitive mitochondrial permeability transition (MPT) pore. Astrocytic GSH levels were only slightly decreased by glucose deprivation or SIN-1 (200 microM) alone. In contrast, a rapid and large depletion of GSH was observed in glucose-deprived/ SIN-1-treated astrocytes. The depletion of GSH occurred before a significant release of lactate dehydrogenase (a marker of cell death). Superoxide dismutase and ONOO-scavengers completely blocked the augmented death, indicating that the reaction of nitric oxide with superoxide to form ONOO was implicated. Furthermore, nitrotyrosine immunoreactivity (a marker of ONOO-) was markedly enhanced in glucose-deprived/SIN-1 -treated astrocytes. Mitochondrial transmembrane potential (MTP) was synergistically decreased in glucose-deprived/SIN-1-treated astrocytes. The glutathione synthase inhibitor L-buthionine-(S,R)-sulfoximine markedly decreased the MTP and increased lactate dehydrogenase (LDH) releases in SIN-1-treated astrocytes. Cyclosporin A, an MPT pore blocker, completely prevented the MTP depolarization as well as the enhanced LDH releases in glucose-deprived/SIN-1-treated astrocytes.

Anatase-Rutile Transition of Precipitated Titanium Oxide with Alcohol Rinsing

The effect of alcohol washing on the anatase-rutile transition of precipitated titanium oxide was investigated using X-ray powder diffraction, Fourier-transform IR spectroscopy, and thermogravimetry. Alcohol (butanol) rinsing accelerated the anatase-rutile transition of precipitated titanium oxide powder so that the onset temperature of transition decreased drastically from 800 degrees C for water-washed powder to 550 degrees C for alcohol-rinsed powder. Alternation of transition kinetics and mechanisms by rinsing media could be confirmed from the analysis of temperature and time dependence of rutile content. The attributability of the chemical state of anatase after crystallization, which contained H(2)O, OH, and organic residues, to the change of transition kinetics with alcohol rinsing will be discussed. Two mechanisms, the effect of residual organics and/or H(2)O(OH), could be suggested on the basis of analysis of the difference between chemical states of water-washed anatase and alcohol-rinsed powder. Copyright 2000 Academic Press.

Changes of hippocampal Cu/Zn-superoxide dismutase after kainate treatment in the rat

In order to evaluate the putative role of Cu,Zn-superoxide dismutase (SOD-1) in the antioxidant defense mechanism during the neurodegenerative process, we examined the level of mRNA, the specific activity and immunocytochemical distribution for SOD-1 in the rat hippocampus after systemic injection of kainic acid (KA). Hippocampal SOD-1 mRNA levels were significantly increased by the seizure intensity 3 and 7 days after KA. These enhanced mRNA levels for SOD-1 were consistent with the increased specific activities for SOD-1, suggesting that the superoxide radical generated in neurotoxic lesion, induced SOD-1 mRNA. The CA1 and CA3 neurons lost their SOD-1-like immunoreactivity, whereas SOD-1-positive glia-like cells mainly proliferated throughout the CA1 sector and had an intense immunoreactivity at 3 and 7 days after KA. This immunocytochemical distribution for SOD-1-positive non-neuronal elements was similar to that for glial fibrillary acidic protein (GFAP)-positive cells. Each immunoreactivity for SOD-1-positive non-neuronal cell or GFAP in the layers of CA1 and CA3 disappeared 3 and 7 days after a maximal stage 5 seizure. On the other hand, activated microglial cells as selectively marked with the lectin occurred in the areas affected by KA-induced lesion. Double-labeling immunocytochemical analysis demonstrated the co-localization of SOD-1-positive glia-like cells and reactive astrocytes as labeled by GFAP or S-100 protein immunoreactivity. This finding suggested that the mobilization of astroglial cells for the synthesis of SOD-1 protein is a response to the KA insult designed to decrease the neurotoxicity induced by oxygen-derived free radicals. Therefore, these alterations might reflect the regulatory role of SOD-1 against oxygen-derived free radical-induced neuronal degeneration after systemic KA administration.

Prolonged exposure to cigarette smoke blocks the neurotoxicity induced by kainic acid in rats

We examined the effects of cigarette smoke (CS) on three parameters associated with kainic acid (KA)-induced neurotoxicity: seizure activity, cell loss in the hippocampus, and increased Fos-related antigen (FRA) expression. Animals were exposed to the main stream of CS from 15 Kentucky 2R1F research cigarettes containing 28.6 mg tar and 1.74 mg nicotine per cigarette, for 10 min a day, 6 days per week, for 4 weeks, using an automatic smoking machine. KA administration (10 mg/kg, i.p.) produced robust behavioral convulsions lasting 4-5 h. Pre-exposure to CS significantly reduced the seizures, mortality, and severe loss of cells in regions CA1 and CA3 of the hippocampus after KA administration. Consistently, pre-exposure to CS significantly attenuated the KA-induced increased FRA immunoreactivity in the hippocampus. In contrast, pretreatment with central nicotinic antagonist, mecamylamine (2 or 10 mg/kg, i.p.) blocked the neuroprotective effects mediated by CS in a dose-dependent manner. These results indicate that CS exposure provides neuroprotection against the KA insult via nicotinic receptor activation.

Inhaled ATP causes mucin release from goblet cells of intact rats

Secretion of mucins from airway epithelial cells has been studied almost exclusively using in vitro cell culture systems. Our understanding of in vivo secretion is greatly limited due to the unavailability of both suitable model systems and adequate assays. It has been reported that ATP induces mucin release from the cultured primary tracheal surface epithelial cell, but there is no clear demonstration of the effect of ATP on mucin release in vivo, which is important to understand the mechanism of mucin release in vivo and also to devise means for regulation of mucin release. The objective of this experiment was to see if inhaled ATP could stimulate airway mucin release in intact rats using both enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. The results were: (1) a new monoclonal antibody (mAbRT03) developed against purified rat mucins specifically recognized high-molecular-mass mucins; (2) ELISA results with conventional gel-filtration assay results are virtually superimposable; (3) inhalation of ATP in intact rats resulted in a dose-independent increase in the amount of mucins in the tracheal lavage fluid with a concomitant decrease in the number of mucin-positive cells in the trachea. We conclude that extracellular ATP can stimulate mucin release from the airway in vivo, and the present rat inhalation system combined with ELISA of the airway secretions should serve a useful model for studying the pharmacology of airway mucin secretion in vivo.

Production and characterization of monoclonal antibodies against human airway mucins

The objective of this study was to generate and characterize monoclonal antibodies (MAbs) against human airway mucins, and therefore, should serve as a useful tool in studying the regulation of airway mucins in various physiological or pathological situations of human airway. As an antigen, we used a high molecular mass mucin preparation purified from the sputum of normal human subjects. Two monoclonal hybridomas, namely MAbs HM02 and HM03 were obtained and they showed strong immunoreactivity against purified or crude mucin in sputum or bronchial washing of normal human subject. With the high immunoreactivity of these MAbs, mucin contents could be analyzed with more than 100-fold dilution of human airway secretion. The antibodies recognized carbohydrate epitopes because their immunoreactivity was completely abolished by treatment of the mucin with 5 mM periodate. Further characterization of MAbs HM02 and HM03 showed that: (1) they belong to the IgM type; (2) they bind to high molecular mass mucins based on Western blot; (3) they could indirectly immunoprecipitate human airway mucin and as we know, this is the first to demonstrate immunoprecipitation of human airway mucin with anti-human mucin antibodies; and (4) they bind to the goblet cell in airway epithelium as well as some submucosal glands based on immunohistochemistry. Therefore, MAbs HM02 and HM03 should be able to serve as an invaluable tool in studying the regulation of airway mucins in various physiological and pathological situations of human airway.

Inhibition of mucin release from airway goblet cells by polycationic peptides

In the present study, we investigated whether polycationic peptides affect mucin release from cultured airway goblet cells. Confluent primary hamster tracheal surface epithelial cells were metabolically radiolabeled with [(3)H]glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of either poly-L-arginine (PLA) or poly-L-lysine (PLL) to assess the effects on [(3)H]mucin release. Possible cytotoxicity by the polycations was assessed by measuring lactate dehydrogenase release, (51)Cr release, and cell exfoliation. The results were as follows: 1) both PLA and PLL inhibited mucin release in a dose-dependent fashion; 2) there was no significant difference in either lactate dehydrogenase release, (51)Cr release, or the number of floating cells between control and treatment groups; 3) the effects of both PLA and PLL on mucin release were completely blocked by neutralizing the positive charges either by pretreatment with heparin or by N-acetylation of the polycations; and 4) both PLA and PLL completely masked the stimulatory effect of ATP on mucin release. We conclude that these polycationic peptides can inhibit mucin release from airway goblet cells without any apparent cytotoxicity, and the inhibitory effect seems to be attributable to their positive charges. These are the first nonsteroidal agents, to the best of our knowledge, that have been shown to inhibit mucin release from airway goblet cells.

A monoclonal antibody against hamster tracheal mucin, which recognizes N-acetyl-galactosamine containing carbohydrate chains as an epitope

Airway mucin that is present in airway secretion, plays an important role in host-defense by trapping airborne particles and removing them by mucociliary transport system. For the study of mucin, it is crucially important to have antibodies specific against mucin because other commonly used methods such as histologic stain for the detection of mucin usually suffer from varying levels of nonspecificity. In this study, we produced a monoclonal antibody (MAb) against hamster airway mucin, which is one of the most commonly used animal species for the study of mucin in vitro, and characterized its immunological properties along with the determination of the epitope it recognizes. The MAb, which was named MAb HTA, was IgM isotype and specific against mucin from both in vitro cell culture and in vivo airway secretion. In Western blot, MAb HTA specifically recognized high molecular weight airway mucin, which was also confirmed by the appearance of peak profile of immunological signal only on void volume fraction in Sepharose CL-4B gel filtration chromatography. It also immunoprecipitated high molecular weight hamster airway mucin with the aid of antimouse IgM agarose. In immunohistochemical stain of hamster trachea, it showed strong signal on airway epithelium and also on the mucin secreting goblet cell granules. The immunological signal was greatly increased by the treatment of endotoxin, which has been reported to cause airway secretory cell metaplasia. The MAb HTA recognized carbohydrate chains containing N-acetyl-galactosamine, one of the linking sugars of airway mucin, as an epitope. Treatment of mucin with N-acetyl-galactosaminidase caused great reduction of immunological signal. To the best of our knowledge, this is the first to report a MAb that recognizes N-acetylgalactosamine, a linking sugar of airway mucin. The specificity of MAb HTA against airway mucin and the clear demonstration of the epitope it recognizes should greatly aid the pharmacological and biochemical study of mucin in various physiological and pathological situations.