bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Cytokines in Monocyte Apoptosis
Authors: Flad H.-D. , Grage-Griebenow E. , Petersen F. , Scheuerer B. , Brandt E. , Baran J. , Pryjma J. , Ernst M.
Published: April 2003

Survival or apoptosis, activation and differentiation, phagocytosis and antigen presentation, migration or participation in granuloma formation are features of freshly recruited blood-borne monocytes in the local environment. In this presentation we describe that human monocytes undergo spontaneous apoptosis in vitro which involves Fas/FasL interactions, and that proinflammatory cytokines such as tumor necrosis factor-α (TNFα), interleukin-1β and granulocyte-monocyte-colony-stimulating factor prevent spontaneous apoptosis. In vitro infection of purified monocytes with low numbers of Mycobacterium tuberculosis H37Rv prevents spontaneous apoptosis. The apoptosis-preventing effect is correlated to the release of TNFα and not due to phagocytosis per se. Furthermore, the minor subset of CD64-negative monocytes is found to be less susceptible to recall antigen-activated CD4-positive T cell-mediated apoptosis than CD64-positive monocytes. Finally, recent findings of our group indicate that the chemokine platelet factor 4 protects monocytes from spontaneous apoptosis and induces the differentiation of monocytes into macrophages. From these findings we conclude that monocyte recruitment, their survival, their differentiation and their functional activity at the site of inflammation are regulated by a cytokine network which needs to be further analyzed in order to design strategies for immune intervention.
α-Melanocyte-Stimulating Hormone as a Mediator of Tolerance Induction
Authors: Luger T.A. , Kalden D.-H. , Scholzen T.E. , Brzoska T.
Published: April 2003

There is accumulating evidence for a strong interaction between components of the nervous system and the immune system. Accordingly, specific receptors for neuropeptides were found to be expressed on immunocompetent cells and several neuropeptides were recognized as potent regulators of immune and inflammatory reactions. Among various neuropeptides such as substance P, calcitonin gene-related peptide and others α-melanocyte-stimulating hormone (α-MSH) was found to be produced in the skin. Moreover, melanocortin receptor 1 which is specific for α-MSH and ACTH is expressed in the skin on keratinocytes, dendritic cells, macrophages and endothelial cells. In monocytes, macrophages and dendritic cells α-MSH inhibits the production and activity of immunoregulatory and proinflammatory cytokines such as IL-2, IFNγ and IL-1. It downregulates the expression of costimulatory molecules such as CD86 and CD40 and induces the production of suppressor factors such as the cytokine synthesis inhibitory factor IL-10. On endothelial cells α-MSH is capable of downregulating the LPS-induced expression of adhesion molecules such as vascular cellular adhesion molecules and E-selectin. Moreover, the LPS-induced activation of transcription factors such as NFκB is downregulated by α-MSH. In a mouse model intravenous or topical application of α-MSH was found to inhibit the induction as well as the effector phase of a contact hypersensitivity reaction and to induce hapten-specific tolerance. Moreover, there is evidence that the N-terminal tripeptide of α-MSH is sufficient for its in vitro and in vivo immunomodulatory effects. These findings indicate that the production of immunosuppressing neuropeptides such as α-MSH by epidermal cells may play an essential role during the pathogenesis of immune and inflammatory reactions in the skin.
The Contact of Human Macrophages with Extracellular Matrix Proteins Selectively Induces Expression of Proinflammatory Cytokines
Authors: Schiffer Ruth , Klein Birgit , Klosterhalfen Bernd , Zwadlo-Klarwasser Gabriele
Published: April 2003

The interaction of macrophages with proteins of the extracellular matrix (ECM) is important for the regulation of the immune and nonimmune functions displayed by these cells. Little, however, is known about the ability of different ECM proteins to transmit inflammatory signals into macrophages. Here we investigated the effect of the ECM proteins collagen type I, fibrin and fibronectin on the expression of the proinflammatory cytokines interleukin-1β (IL-1β) and IL-8 using RT-PCR, Northern and Western blot analysis and ELISA technique. It was found that collagen strongly induced IL-1β and IL-8 expression in the macrophages. Fibronectin also stimulated cytokine expression, however, the amounts of the specific mRNAs were significantly lower compared to those induced by collagen. On the protein level IL-1β revealed a close correlation to the mRNA expression. In contrast, fibrin did not elicit any IL-1β and IL-8 response. These data show that different ECM proteins vary in their ability to induce proinflammatory cytokine expression in human macrophages suggesting that the protein composition of the ECM might be crucial in the initiation of inflammatory processes.
Intimal Thickness and Layering, and Smooth Muscle Cell Phenotypes in Aorta of Youth
Authors: Rao Raghunatha N. , Falls D. Greer , Gerrity Ross G. , Sethuraman Sankara N. , Thiruvaiyaru Dharma S.
Published: April 2003

Proneness to the lesions of atherosclerosis varies along the length and circumferential topography of the aorta. Smooth muscle cells, in particular those of the ‘modulated’ synthetic phenotype which are able to proliferate and synthesize matrix proteins, are considered to play an important role in lesion progression. We report on a study of the aortic intima at a lesion-prone site from abdominal aorta and a lesion-resistant site from thoracic aorta in young humans to determine (1) whether the histologic structure and the smooth muscle cell composition show quantitative differences between lesion-prone and lesion-resistant aortic sites; (2) whether there are gender differences, and (3) whether any differences increase in degree with increasing age in this young population. Material for this study was obtained as part of the NIH-funded multicenter study on Pathobiological Determinants of Atherosclerosis in Youth (PDAY) from autopsies of male and female subjects between the ages of 15 and 34, victims of unexpected sudden death, usually from trauma. The samples consisted of strips of abdominal and thoracic aorta, all derived from the same anatomical sites standardized in the PDAY studies. The thickness of total intima (TI) and its elastic hyperplastic (EH) layer was measured. Smooth muscle cells of all types (SMC) and separately those of the synthetic phenotype (SynSMC) were quantified in each site using immunohistochemical procedures in replicate sections of uniform thickness. The intima of the atherosclerotic lesion-prone dorsal half of the abdominal aorta (AD) shows significant differences from the lesion-resistant ventral half of thoracic aorta (TV) in that (1) its EH layer is significantly thicker; (2) its EH layer has a comparatively higher number of both total SMC and SynSMC, even when adjusted for intimal thickness, and (3) the age-related increase in thickness of both TI and EH layer of AD is much greater than that of TV.
Increased O2 Consumption and Positive Inotropy Caused by Cyclic GMP Reduction Are Not Altered after L-Type Calcium Channel Blockade
Authors: Leone Jr. Richard J. , Naim Karen L. , Scholz Peter M. , Weiss Harvey R.
Published: April 2003

We tested the hypothesis that increased O2 consumption and inotropy after reduction of myocardial cyclic guanosine monophosphate (cGMP) are mediated through L-type calcium channels. Anesthetized, open-chest New Zealand white rabbits were divided into four groups. Hearts were exposed to control vehicle (n = 8); LY83583 (LY, 10–3 mol/l, guanylate cyclase inhibitor, n = 9); nifedipine (nif, 10–4 mol/l, L-type calcium channel blocker, n = 8), or nif+LY (n = 6). Vehicle or compound was applied topically to the epicardium for 15 min. Subepicardial (EPI) blood flow increased (from 213 ± 22 to 323 ± 24 ml/min/100 g) in the presence of LY, as did subendocardial (ENDO) blood flow (from 238 ± 20 to 333 ± 38 ml/min/100 g). O2 consumption increased in the presence of LY: 18.0 ± 1.0 (EPI) and 17.0±0.6 (ENDO) ml O2/min/100 g as compared with 9.5 ± 2.0 (EPI) and 10.6 ± 2.5 (ENDO) in the control group. The increase in O2 consumption with LY was undiminished in the presence of nif (nif+LY group 21.0 ± 3.0 ml O2/min/100 g EPI and 22.1 ± 3.8 ENDO). Nif alone decreased left ventricular dP/dtmax from (2,762 ± 197 to 2,413 ± 316 mm Hg/s) and maximal rate of change in wall thickness (dW/dtmax from 13.5 ± 2.0 to 9.5 ± 0.8 mm/s), while percent change of wall thickness (from 21.3 ± 3.3 to 31.3 ± 7.2) and dW/dtmax (from 13.3 ± 3.0 to 15.3 ± 2.3 mm/s) increased in the nif+LY group. Thus, the positive O2 consumption and inotropic effects of decreasing cGMP were undiminished by nif. These results suggest that the cGMP reduction induced increases in O2 consumption and that inotropy may not be mediated through L-type calcium channels.
Inhibition of Testicular Steroid Metabolism by Administration of 1-Aminobenzotriazole to Rats
Authors: Soltis Michael , Colby Howard D.
Published: April 2003

Effects of 1-aminobenzotriazole (ABT) on testicular steroid metabolism were evaluated in rats. Administration of ABT to adult male rats caused dose-dependent decreases in testicular microsomal and mitochondrial cytochrome P450 concentrations. Significant losses of P450 occurred within 8 h of ABT treatment. Accompanying the declines in testicular P450 content were decreases in microsomal 17α-hydroxylase and mitochondrial cholesterol sidechain cleavage activities. Incubation of testicular microsomes or mitochondria in vitro with ABT plus an NADPH-generating system had no effect on P450 concentrations or on rates of steroid metabolism. By contrast, incubation of hepatic microsomes with ABT under the same conditions decreased P450 levels and xenobiotic-metabolizing activity. The results indicate that ABT in vivo causes inactivation of steroidogenic P450 isozymes in the testis, but the mechanism of inactivation differs from that on xenobiotic-metabolizing isozymes.
Differentiation of the Inhibitory Effects of Calcium Antagonists on Abnormal Behaviors Induced by Methamphetamine or Phencyclidine
Authors: Hori Yusuke , Takeda Hiroshi , Tsuji Minoru , Matsumiya Teruhiko
Published: April 2003

The abnormal behaviors induced by methamphetamine (MAP: 1 mg/kg) or phencyclidine (PCP: 10 mg/kg) were measured using behavioral analysis following the microinjection of one of three calcium (Ca) antagonists (nifedipine: Nif, nicardipine: Nic and flunarizine: Flu) into the rat caudate putamen or amygdala. The intraperitoneal administration of MAP or PCP induced abnormal behaviors in a time-dependent manner; the maximum locomotor activity was measured 30–45 min after the administration of MAP or PCP. This hyperactivity was sustained for more than 2 h. Following microinjection of these Ca antagonists into the caudate putamen, each showed a different pattern of inhibition on MAP- or PCP-induced abnormal behaviors. Nic and Flu were effective at reducing these abnormal behaviors, in contrast, Nif was ineffective. In particular, the inhibitory effect of Nic was stronger than that of Flu. Microinjection of these Ca antagonists into the amygdala did not show any reductive effect on the hyperactivity induced by MAP or PCP. These results demonstrate that these Ca antagonists have different pharmacological properties and that both L- and T-type Ca2+ channels modulate the dopamine release in the rat caudate putamen. These results further lead us to suggest the presence of a subtype of L-type Ca2+ channels in the caudate putamen.
Esculentoside A Inhibits Tumor Necrosis Factor, Interleukin-1, and Interleukin-6 Production Induced by Lipopolysaccharide in Mice
Authors: Ju Dian Wen , Zheng Qin Yue , Cao Xuetao , Fang Jun , Wang Hong Bin
Published: April 2003

Esculentoside A, a kind of saponin isolated from the root of the Chinese herb Phytolaca esculenta, is reported to possess potent anti-inflammatory effects in acute and chronic experimental models. In the present study, we investigated the effects of esculentoside A on the production of tumor necrosis factor (TNF), interleukin-1 (IL-1) and interleukin-6 (IL-6) induced by lipopolysaccharide (LPS) in mice. In vitro experiments demonstrated that esculentoside A (0.1–10 µmol/l) significantly reduced the release of TNF from the peritoneal macrophages derived from mice pretreated with thioglycolate. IL-1 and IL-6 secretion was also obviously inhibited in a concentration-dependent manner by esculentoside A from 0.01 to 10 µmol/l. In vivo experiments demonstrated that detectable TNF was observed 0.25 h after injection, was maximal at 0.5 h, and returned to baseline at 4 h. Maximal production of IL-1 and IL-6 were observed to be 1 and 2 h, respectively, after injection of LPS. Pretreatment of mice with 5, 10, or 20 mg/kg esculentoside A once a day for 7 consecutive days dose-dependently decreased the TNF, IL-1 and IL-6 levels in the sera of mice following LPS challenge. TNF, IL-1, and IL-6 are important cytokines involved in the pathogenesis of inflammatory lesions. Inhibition of inflammatory cytokine production may contribute to the anti-inflammatory effects of esculentoside A.
Inhibition of Anaphylaxis by Sulfasalazine in Rats
Authors: Lee E.H. , Kim Hyung-Min
Published: April 2003

We studied the effect of sulfasalazine on anaphylaxis. Sulfasalazine dose-dependently inhibited systemic anaphylaxis induced by compound 48/80 in rats. Sulfasalazine also inhibited local anaphylaxis activated by anti-dinitrophenyl (anti-DNP) IgE. Moreover, sulfasalazine dose-dependently inhibited histamine release in the peritoneal mast cells activated by compound 48/80 or anti-DNP IgE. All of these effects were comparable to those of the disodium cromoglycate (reference drug) tested. When sulfasalazine was added, the level of cAMP in rat peritoneal mast cells transiently and significantly increased about 6-fold compared with that of basal cells. Our studies provide evidence that sulfasalazine may be beneficial in the treatment of anaphylaxis.
Liver Dihydropyrimidine Dehydrogenase Activity in Human, Cynomolgus Monkey, Rhesus Monkey, Dog, Rat and Mouse
Authors: Sludden Julieann , Hardy Sarah C. , VandenBranden Mark R. , Wrighton Steven A. , McLeod Howard L.
Published: April 2003

Interspecies differences in dihydropyrimidine dehydrogenase (DPD), the initial and rate-limiting enzyme in pyrimidine degradation, were assessed in cytosol from livers isolated from human, monkey, dog, rat, and mouse. Hepatic DPD activity was measured by an HPLC assay with on-line radioactivity detection, using 14C-5-fluorouracil as a substrate. Activity was highly variable within each species and significant interspecies differences in liver DPD activity were observed. The order of activity was mouse > rat > human > dog ≥ cynomolgus monkey > rhesus monkey. These data suggest that careful selection must be made when choosing in vivo models of human DPD for the preclinical development of novel fluoropyrimidine anticancer agents and DPD inhibitors.
Pharmacokinetics and Pharmacodynamics of Mibefradil in Hypertensive Patients with Varying Degrees of Renal Insufficiency
Authors: Welker Horst A. , Weidekamm Erhard , Houwing Nathalie , de Chatel Rudolf
Published: April 2003

Mibefradil, the first member of the tetralol derivatives, a new class of calcium antagonists, is used for the treatment of hypertension and angina pectoris. This study was designed to investigate the effect of varying degrees of chronic renal impairment on mibefradil pharmacokinetics and pharmacodynamics. Neither pharmacokinetic nor pharmacodynamic parameters varied as a function of renal status. Additionally, hemodialysis removed only a relatively small fraction of drug from the body. It was concluded that the majority of renal-failure patients will not require a change in mibefradil dosage relative to patients with normal renal function. Following hemodialysis, supplemental mibefradil treatment should not be necessary.
Mechanism by Which Orally Administered Leminoprazole Stimulates Mucus Synthesis in Rats
Authors: Takahashi Satoru , Okabe Susumu
Published: April 2003

We examined the mechanism by which leminoprazole (an acid pump inhibitor) stimulates mucus synthesis in rats. Leminoprazole and omeprazole were administered to rats, and then the gastric fragments were isolated from the fundus of their stomachs. Mucus synthesis was assessed by [3H]leucine and [3H]glucosamine incorporation by the fragments into high-molecular-weight materials. After oral administration of leminoprazole, mucus synthesis by the gastric fragments was dose-dependently stimulated, while acid secretion was inhibited. Omeprazole had no effect on mucus synthesis, although it potently inhibited acid secretion. Treatment with NG-nitro-L-arginine methyl ester (L-NAME), but not indomethacin, caused a reduction of leminoprazole-stimulated synthesis of gastric mucus in a dose-dependent manner. The inhibitory action of L-NAME was restored by the concomitant administration of L-arginine, but not D-arginine. Intragastric administration of leminoprazole to pylorus-ligated rats also stimulated mucus synthesis without inhibiting acid secretion. In contrast, in the case of intraperitoneal administration, leminoprazole exerted a potent antisecretory effect, but failed to promote mucus synthesis. Exposure of leminoprazole to the luminal surface of the gastric mucosa did not cause any damage. We conclude that orally administered leminoprazole, via direct effect toward the gastric mucosa, stimulates mucus synthesis in rats probably through nitric oxide mediation. The stimulatory effect of leminoprazole on mucus synthesis is independent of its antisecretory effect.
Relaxant Effects of Sodium Nitroprusside and NONOates in Rabbit Basilar Artery
Authors: Salom Juan B. , Barberá María D. , Centeno José M. , Ortí Marta , Torregrosa Germán , Alborch Enrique
Published: April 2003

NONOates are a new class of NO donors that have proven useful for studying the effects of spontaneous and chemically predictable NO release in biologic systems. In order to assess their potential as vasodilatatory drugs in the cerebrovascular bed we have compared the relaxant effects of the classical nitrovasodilator sodium nitroprusside (SNP) and three NONOates, diethylamine/NO complex (DEA/NO), spermine/NO complex (SPER/NO), and diethylenetriamine/NO complex (DETA/NO) in isolated rabbit basilar arteries precontracted with UTP. The 4 NO donors induced full relaxation of the UTP-induced tone, with the following order of potency: SNP > DEA/NO > SPER/NO > DETA/NO. Relaxations induced by SNP and DETA/NO were not modified in rubbed (endothelium denuded) arteries in which acetylcholine-relaxations were almost abolished. On the other hand, relaxations to SNP and SPER/NO were more potent and effective in histamine-precontracted arteries than in KCl-precontracted arteries. Methylene blue significantly inhibited SPER/NO-induced relaxations in both KCl- and histamine-precontracted arteries while SNP-induced relaxations were only slightly inhibited by methylene blue in KCl-precontracted arteries. This study shows that the NO donors SNP, DEA/NO, SPER/NO and DETA/NO have quantitatively different relaxant effects in rabbit basilar arteries according to their rate of NO release. Relaxations are not mediated by endothelial factors, and are inhibited by arterial depolarization. Finally, cGMP formation is involved in relaxation induced by NONOates and much less in SNP-induced relaxation.
Portal Hypotensive Effects of DL-028 and Prazosin on Portal Hypertensive Rats
Authors: Huang Yi-Tsau , Lin Li-Chih , Chern Ji-Wang , Lin Han-Chieh , Hong Chuang-Ye
Published: April 2003

The portal hypotensive effects of prazosin and DL-028 (chem- ical name: 3-[[4-(2-methoxyphenyl)piperazin-1-yl]methyl]- 2,3-dihydroimidazo[1,2-c]quinazolin-5(6H)-one(27b)), a synthetic α1-adrenoceptor antagonist, were assessed in portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation in Sprague-Dawley rats. Two weeks after ligation, when the hyperdynamic state was stabilized the rats were anesthetized after an overnight fast and cannulated for measuring mean arterial pressure (MAP), portal venous pressure (PVP), cardiac index (CI) and heart rate (HR). Both DL-028 and prazosin (1, 3.3 and 10 µg/kg) induced dose-dependent decreases of PVP and MAP after intravenous infusion, with effects lasting for longer than 30 min. The maximum percentage reduction of PVP after DL-028 was 10, 10 and 15%, respectively, for the dosages given (1, 3.3 and 10 µg/kg), and 5, 12 and 25%, respectively, after prazosin. CI was not changed by either drug. HR was not changed by either drug except DL-028 at 10.0 µg/kg with a bradycardiac effect. Our results showed that both DL-028 and prazosin reduced PVP in portal hypertensive rats.
Contractile and Relaxant Effects of Tetrapentylammonium Ions in Rat Isolated Mesenteric Artery
Authors: Kwok K.H. , Chan N.W.K. , Lau C.W. , Huang Yu
Published: April 2003

Both contractile and relaxant responses to tetrapentylammonium ions (TPA+) were studied in rat isolated mesenteric artery. TPA+ (5–10 µmol/l) caused a sustained increase of muscle tension. The contractile effect of TPA+ (10 µmol/l) was dependent upon the presence of extracellular Ca2+ but independent of the presence of endothelium. TPA+ (10–50 µmol/l) induced biphasic contraction, and the amplitude of peak and sustained tension decreased with increasing TPA+ concentration. TPA+ (100–300 µmol/l) only produced monophasic contraction. TPA+ (50 µmol/l) abolished the transient contraction induced by caffeine (10 mmol/l) or phenylephrine (1 µmol/l) in the absence of extracellular Ca2+. Nifedipine and verapamil concentration-dependently reduced the TPA+-induced contraction with respective IC50 values of 1.34 ± 0.24 and 9.46 ± 1.36 nmol/l, these values were similar to 1.35 ± 0.21 and 16.07 ± 1.71 nmol/l, respectively, for the inhibitory effects of nifedipine and verapamil on the high K+ (60 mmol/l)-induced contraction. TPA+ (>10 µmol/l) concentration-dependently reduced the phenylephrine (1 µmol/l)-, U46619 (30 nmol/l)-, endothelin I (10 nmol/l)- and high K+ (60 mmol/l)-induced sustained tension with respective IC50 values of 53.7 ± 9.5, 31.9 ± 5.3, 30.9 ± 3.4 and 20.9 ± 2.8 µmol/l. The present results indicate that TPA+ at low concentrations could contract the arterial smooth muscle probably through promoting Ca2+ influx. At higher concentrations (>20 µmol/l), TPA+ relaxes arterial smooth muscle probably through inhibition of both nifedipine-sensitive Ca+ channels and internal Ca2+ release. TPA+, unlike other quaternary ammonium ions, could therefore act at multiple sites in arterial smooth muscle.
Lisuride Acts at Multiple Sites to Induce Ocular Hypotension and Mydriasis
Authors: Potter David E. , Ogidigben Miller J. , Chu Teh-Ching
Published: April 2003

Topically unilaterally applied lisuride caused dose-related lowering of intraocular pressure in ipsilateral (treated) but not in contralateral eyes of normal rabbits. The ocular hypotensive response induced by lisuride was antagonized by pretreatment with metoclopramide, a dopamine receptor antagonist, and was partially reduced by local sympathetic denervation. In contrast to the unilateral effect on intraocular pressure, lisuride caused mydriasis in both eyes. Mydriasis was of greater magnitude and more sustained in normal eyes compared to sympathetically denervated eyes. Additional in vivo experiments demonstrated that lisuride caused dose-related suppression of neuronally initiated contractions of cat nictitating membrane. In in vitro experiments lisuride caused dose-related inhibition of norepinephrine release from isolated rabbit iris-ciliary bodies. Pretreatment with Bay K 8644, a calcium channel activator, did not attenuate lisuride-induced inhibition of norepinephrine release in isolated rabbit iris-ciliary bodies. Because lisuride pretreatment caused no change in isoproterenol-stimulated cAMP accumulation in isolated iris-ciliary bodies, suppression of adenylate cyclase was unlikely. It is concluded that the ocular hypotensive effect of lisuride results, in part, from activation of prejunctional dopaminergic receptors on peripheral sympathetic nerves in the anterior segment of the eye but may also involve antagonism on peripheral postjunctional α1 adrenoceptors as well. Bilateral increases in pupil diameter antagonized by metoclopramide suggest a stimulatory action of lisuride on dopamine receptors in the central nervous system.
GABAA Receptor Subunit mRNAs in Rat Superior Cervical Ganglia
Authors: Liu Zhi Fang , Burt David R.
Published: April 2003

γ-Aminobutyric acid (GABA), one of the most important neurotransmitters in the brain, is also found in the periphery. GABAA receptors are chloride channels opened by GABA whose presence in the rat superior cervical ganglion has been indicated by functional and binding measurements. We describe the first molecular data on the possible subunit composition of these receptors, detecting mRNAs for 12 subunits (α1–5, β1–3, γ1–3, δ) by reverse-transcriptase polymerase chain reaction. Preliminary quantitation gave highest levels (in descending order) for the γ2 (both short and long forms), β3, γ3, and α1 subunits.
In vitro Biotransformation of a Novel Antimalarial Cysteine Protease Inhibitor in Human Liver Microsomes
Authors: Zhang Yuanchao , Guo Xisheng , Lin EmilT. , Benet LeslieZ.
Published: April 2003

4-Dimethylamino-4′-(imidazol-1-yl)chalcone (RL3142) is a newly developed antimalarial cysteine protease inhibitor. Four metabolites (M1–M4) were found in human liver microsomes and their structures were identified by LC/MS/MS. Two primary metabolites, M2 (minor) and M4 (major), were determined to be the N-demethylated product (M2) and the product (M4) resulting from 1,2-hydrogenation of the α,β-unsaturated ketone moiety of the parent compound. A combined approach utilizing selective P450 inhibitors, immunoinhibition with CYP3A and NADPH P450 reductase antibodies, and cDNA expressed human CYP3A4 and NADPH P450 reductase, was used for identification of enzymes responsible for the biotransformation. For formation of M2, both a rabbit CYP3A polyclonal antibody (110 µl/mg microsomal protein) and ketoconazole (2 µmol/l), a CYP3A inhibitor, showed about 50% inhibitory effects; other specific inhibitors of CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6 and CYP2E1 showed no significant effects. For formation of M4, neither CYP3A antibody nor the above mentioned CYP inhibitors exhibited inhibitory effects. Anti-rat NADPH P450 reductase serum (50 µl/100 µg microsomal protein) exhibited 70 and 58% inhibitory effects on M2 and M4 formation, respectively. Incubation of RL3142 with cDNA expressed human NADPH P450 reductase yielded formation of M4, but not M2. Carbon monoxide inhibited formation of M2 and M1 (the reduced product of M2), but had no effect on M4 and M3 (the reduced product of M4) formation. Collectively, NADPH P450 reductase solely catalyzed reduction of RL3142 to M4, whereas CYP3A contributed in part to formation of M2.
Correlation between the in vivoEff icacy of GPIIb/IIIa Receptor Antagonists (m7E3, MK-383 and DMP-728) and ex vivo Platelet Inhibition
Authors: Huang Jinbao , Rebello Sam S. , Faul Jessica D. , Lucchesi Benedict R.
Published: April 2003

In vivo antithrombotic efficacy of GPIIb/IIIa receptor antagonists (m7E3, MK-383 and DMP-728) was studied with respect to their ex vivo platelet inhibition in heparinized platelet-rich plasma (hPRP) and citrated platelet-rich plasma (cPRP) using a canine model of carotid artery thrombosis. For each drug group (n = 6), the right carotid artery was used as control vessel and resulting occlusive thrombus was kept in situ to examine the direct thrombolytic efficacy of the antagonists. Thirty minutes after occlusion of control vessel, a low or high dose of each antagonist was administered and the left carotid artery was used as test vessel. All control vessels occluded within 86–96 min in response to electrolytic injury. The incidence of occlusion with lower doses of m7E3, DMP-728, and MK-383 was 100, 33 and 100%, respectively; corresponding times to occlusion were 174, 220 and 118 min. Lower doses inhibited ADP- or AA-induced platelet aggregation in cPRP (>80%). Incidence of occlusion with high doses of m7E3, DMP-728 and MK-383 was 33, 0 and 0%, respectively; corresponding times to occlusion were 209, >240 and >240 min. Higher doses inhibited aggregation in cPRP (>80%), but only partially in hPRP (45–66%). Dose-dependent prolongation of bleeding time occurred with all antagonists. None of the antagonists lyzed preformed thrombi in control vessels. The results indicate that ex vivo platelet aggregation conducted in hPRP, as opposed to conventional cPRP, provides a better assessment of the in vivo efficacy of GPIIb/IIIa receptor antagonists.
Effects of Eprosartan on Glomerular Injury in Rats with Reduced Renal Mass
Authors: Gandhi Mehul , Meyer Timothy W. , Brooks David P.
Published: April 2003

The effects of the selective angiotensin AT1 receptor antagonist, eprosartan, were evaluated in experimental renal disease. Five-sixth nephrectomy in male Munich-Wistar rats led to the development of hypertension, proteinuria and remnant glomerulosclerosis. Administration of the AT1 receptor antagonist, eprosartan, for 4 weeks resulted in inhibition of angiotensin II activity as confirmed by a reduced blood pressure response to exogenous angiotensin II challenge. Compared to vehicle treatment, eprosartan normalized blood pressure, reduced proteinuria and limited remnant glomerulosclerosis. These data suggest that eprosartan may provide a new tool in the treatment of progressive renal disease.
Insulin Reversal of Impaired Nitrergic Transmission in the Anococcygeus Muscle from Diabetic Rats
Authors: Way Kerrie J. , Reid Julianne J.
Published: April 2003

The aim of this study was to investigate whether insulin could reverse the impairment in nitrergic neurotransmission in the anococcygeus muscle from streptozotocin-induced diabetic rats. Relaxations to nitrergic nerve stimulation and sodium nitroprusside were significantly reduced in precontracted muscles from 8- and 4-week diabetic rats compared to the corresponding control rats. Treatment of diabetic rats with Lente insulin (1–12 units/day s.c.) for the final 4 weeks of the 8-week diabetes duration reversed the reductions, but treatment of diabetic rats with insulin for the last week only did not. The impairment of relaxations was also not altered by in vitro exposure of muscles from 8-week diabetic rats to soluble insulin (0.02 units/ml, 2 h). The findings suggest that in vivo insulin treatment can reverse the existing diabetes-induced impairment of nitrergic transmission in rat anococcygeus muscle. However, short-term treatment with insulin, either in vivo or in vitro, does not reverse the impairment.
Effect of 5-(N,N-Dimethyl)-Amiloride, a Specific Inhibitor of Na+/H+ Exchanger, on the Palmitoyl-L-Carnitine-Induced Mechanical and Metabolic Derangements in the Isolated Perfused Rat Heart
Authors: Arakawa Johji , Hara Akiyoshi
Published: April 2003

The present study was carried out to determine the effect of 5-(N,N-dimethyl)-amiloride (DMA), a specific inhibitor of the Na+/H+ exchanger, on the cardiac mechanical and metabolic derangements induced by palmitoyl-L-carnitine (PALCAR). Rat hearts were perfused aerobically at a constant flow according to the Langendorff technique, while being paced electrically. PALCAR (5 μmol/l) increased the left-ventricular end-diastolic pressure, decreased the left ventricular developed pressure (i.e. mechanical dysfunction), decreased the tissue level of ATP and increased the tissue level of AMP (i.e. metabolic change). DMA (10 or 20 μmol/l) attenuated the mechanical and metabolic alterations induced by PALCAR in a concentration-dependent way. Nevertheless, DMA (10 or 20 μmol/l) did not affect the mechanical function or energy metabolism in the normal (PALCAR-untreated) heart. These results suggest that inhibition of the Na+/H+ exchanger with DMA is effective in attenuating the PALCAR-induced mechanical and metabolic derangements in the heart.
Studies on the Stereoselective Metabolism of Citalopram by Human Liver Microsomes and cDNA-Expressed Cytochrome P450 Enzymes
Authors: Olesen Ole V. , Linnet Kristian
Published: April 2003

The involvement of CYP enzymes in the metabolism of citalopram was studied, inclusive the conversion of demethylcitalopram to didemethylcitalopram and the formation of citalopram N-oxide, which both have not been considered previously. Using human mixed liver microsomes and cDNA-expressed CYP enzymes, we confirmed that CYP3A4, 2C19 and 2D6 are involved in the first demethylation step of citalopram, all favouring conversion of the biologically active S-enantiomer. Inhibitor studies indicated that at therapeutic citalopram concentrations CYP3A4 was responsible for 40–50% of demethylcitalopram formation, while the contribution of CYP2C19 increased and that of CYP2D6 tended to decrease with increasing drug concentration. CYP2D6 exclusively mediated the second demethylation step, and citalopram N-oxide was also exclusively formed by CYP2D6. None of the studied CYP enzymes mediated deamination to the propionic acid derivative.
Simultaneous Determination of Paroxetine, Risperidone and 9-Hydroxyrisperidone in Human Plasma by High-Performance Liquid Chromatography with Coulometric Detection
Authors: Schatz Dieter S. , Saria Alois
Published: April 2003

A method for the simultaneous determination of paroxetine, risperidone and its main metabolite 9-hydroxyrisperidone in human plasma has been developed. The procedure involved a multistep solid-phase liquid extraction with an internal standard. The drugs were separated on a cyano column followed by coulometric detection. This method described here has sufficient sensitivity to quantitate paroxetine accurately in the range 5–500 ng/ml with a lower limit of detection of 1 ng/ml and risperidone and its main metabolite 9-hydroxyrisperidone in the range 2–100 ng/ml with a lower limit of detection of 1 ng/ml when 1 ml of plasma was used for the analysis. The precision, accuracy and specificity have been proven, and show that the method is reliable for clinical studies and routine drug monitoring.
Drug Transport in the Mammalian Central Nervous System: Multiple Complex Systems
Authors: Spector Reynold
Published: April 2003

The rate of entry into and distribution of drugs and endogenous substances within the mammalian central nervous system (CNS) depend on the peculiar anatomy of the blood-brain and blood-cerebrospinal fluid barriers, the physicochemical nature of the substance or drug, and in many cases, multiple, complex specialized carriers. This review summarizes a systemic methodological and integrative approach to understanding the pharmacokinetic behavior of many drugs in the CNS in the context of the CNS barrier systems, focusing on recent data, several broad principles and selected examples. Standards of proof for valid conclusions are emphasized.
Thrombin Stimulates Pertussis Toxin-Sensitive and -Insensitive GTPase Activitiesand ADP-Ribosylation of Gi in Human Neuroblastoma SH-EP
Authors: Ogino Yoshio , Sakamoto Yoshikazu , Kinouchi Takashi , Shimizu Naokata
Published: April 2003

Kinetic interaction between thrombin receptor and G proteins was investigated in human epithelial neuroblastoma cell line, SH-EP. In these cells, both α-thrombin and SFLLRNP (one-letter amino-acid code) stimulated GTPase activity and enhanced cholera toxin-catalyzed ADP-ribosylation of Gi2 in a concentration-dependent manner. Basal GTPase activity was attenuated by pertussis toxin treatment by 35%, however, agonist stimulation was preserved significantly. These results together indicated that thrombin receptor simultaneously activates Gi2 and PTX-insensitive G protein(s).
Meloxicam Inhibits Prostaglandin E2 Generation via Cyclooxygenase 2 in the Inflammatory Site but Not That via Cyclooxygenase 1 in the Stomach
Authors: Ogino Keiko , Hatanaka Ko , Kawamura Michiko , Ohno Takashi , Harada Yoshiteru
Published: April 2003

We studied the effects of meloxicam on prostanoid levels, both in the inflammatory site in rat carrageenin-induced pleurisy and in the rat stomach injected with 1 mol/l NaCl solution, to clarify the relationship between its low gastric toxicity and its relative cyclooxygenase (COX) 2 selectivity. NS-398 (3 mg/kg), a highly selective COX-2 inhibitor, and meloxicam (3 mg/kg) exhibited anti-inflammatory effects in the pleurisy model. Prostaglandin (PG) E2 thromboxane (TX) B2 and 6-keto-PGF1α were detectable in the inflammatory site. Anti-inflammatory doses of NS-398 and meloxicam each suppressed the intrapleural PGE2 level at 5 h as potently as piroxicam (3 mg/kg) as aspirin (100 mg/kg), both of which are nonselective COX inhibitors. NS-398 was much less potent than the other three in suppressing the levels of TXB2 and 6-keto-PGF1α. These results suggest that PGE2 may be produced mainly via COX-2 in this model and that meloxicam may inhibit COX-2 in the inflammatory site. Piroxicam completely inhibited the increase in gastric PGE2 induced by administering 1 mol/l NaCl solution into the rat stomach. Nimesulide (3 mg/kg), another selective COX-2 inhibitor, however, never affected this increase, suggesting that the gastric PGE2 may be produced via COX-1. The anti-inflammatory dose of meloxicam caused statistically nonsignificant suppression of the PGE2 level, by approximately 50%. These results suggest that the potent anti-inflammatory effect of meloxicam, accompanied with low gastric toxicity, may be related to its relative selectivity for COX-2 over COX-1.
Nasalization of Vowels in Nasal Environments in Babbling: Evidence for Frame Dominance
Authors: Matyear Christine L. , MacNeilage Peter F. , Davis Barbara L.
Published: April 2003

An emerging concept for the characterization of the form of babbling and early speech is ‘frame dominance’: most of the variance arises from a frame provided by open-close mandibular oscillation. In contrast, the tongue – the most versatile articulator in adults – plays only a minor role in intersegmental and even intersyllabic changes. The contribution of another articulator – the soft palate – to time-domain changes in babbling was evaluated in an acoustic analysis of 433 consonant-vowel-consonant sequences produced by 3 infants. Strong nasal effects on vowels in symmetrical consonantal environment were observed in the form of a lower frequency first formant region in low vowels and a lower frequency second formant region in front vowels. These results, the first of which also occurs in adults, were complemented by perceptual tendencies for transcribers to transcribe more mid vowels relative to low vowels and more central vowels relative to front vowels in nasal environments. Thus the soft palate is like the tongue in making only minor contributions to time-domain changes in babbling, and this is considered to be additional evidence for the frame dominance conception.
Consistency of Tone-Syllable Alignment across Different Syllable Structures and Speaking Rates
Authors: Xu Yi
Published: April 2003

Previous studies have reported that F₀ contours of lexical tones in Mandarin are closely aligned with the syllables that carry them and that this alignment is late-adjusted so that the most appropriate F₀ contour of a tone occurs mainly in the later portion of the host syllable. These studies, however, examined tone alignment only in syllables with a simple CV structure. The present study compared tone-syllable alignment patterns in syllables with a final nasal (the only final consonant allowed in Mandarin) to those without a final nasal at three speaking rates – normal, fast and slow. Experiment 1 found that regardless of internal syllable structure, the F₀ contours for all of the four Mandarin tones maintain a consistent alignment to the syllables that carry them. Experiment 2 found that whether or not the syllable has a final nasal and regardless of speaking rate, the F₀ peak associated with the R (rising) tone always occurs near the offset of the R-tone-carrying syllable, the onset of the F₀ rise always occurs near the center of the syllable and the slope of the rise does not vary systematically with either syllable structure or speaking rate. These findings are interpreted as indicating that the syllable is the proper domain for tone implementation and that tone contours such as rising and falling are probably implemented as integral dynamic targets rather than as sequences of static targets.
Thai Final Stops: Cross-Language Perception
Authors: Abramson Arthur S. , Tingsabadh Kalaya
Published: April 2003

As part of a project seeking a better understanding of the links between speech production and perception, we have conducted experiments on the perception of Thai word-final stop consonants by native speakers of Thai and native speakers of American English. The final stops of Thai are never released audibly. In English, however, final stops occur with and without audible releases. Previous work has shown that released stops are likely to be more intelligible than unreleased ones. That is, identification is better when information as to place of articulation in the formant transitions of the closing articulatory gesture is supplemented by acoustic information in a release burst. Both languages have labial, alveolar, and velar places of articulation, but Thai also has glottal closure. Two native speakers of Thai recorded sets of monosyllabic words minimally distinguished by the four final stops . Randomized lists of the isolated words were presented to 19 native speakers of English who responded with the labels ‘p’, ‘t’, ‘k’, and ‘other’. They were also presented to 30 native speakers of Thai for identification in Thai script as words. The highly significant differences between the two groups imply the possibility that the closing gestures of the Thai stops include a component that compensates somewhat for the absence of release, a component to which the English speakers are perhaps less well attuned. Such an interference will be tested in future work by tracking of the gestures in both languages with the Haskins Laboratories magnetometer.
Singing Birds, Playing Cats, and Babbling Babies: Why Do They Do It?
Authors: Sjölander Sverre
Published: April 2003

Rarely, animals do what they do because they are aware of the function of the behaviour or its outcome. Instead, they will very often perform behaviour out of context, spontaneously, as play. The impression (strengthened by introspection in the human species) is that they do it because they get some kind of internal reward. Nevertheless, such seemingly meaningless behaviour may have an ultimate function to adjust behavioural programs to the body, to practice, to perfect the execution of the behaviour. If the proximate reason for doing what the animal does may be to attain a pleasurable state, the ultimate, evolutionary reason may still be that increased practice will give some gain in fitness. If one presupposes internal rewarding and punishing systems as intervening factors, it becomes much simpler to explain why birds sing, kittens play or babies babble without any outer reward and out of any functional context, more than needed from a strictly functional view, spontaneously and just for the fun of it.
Two Cases of Cerebral Aneurysms in HIV+ Children
Authors: Fulmer Benjamin B. , Dillard Stephanie C. , Musulman Elizabeth M. , Palmer Cheryl A. , Oakes Jerry W.
Published: April 2003

Two cases of fusiform cerebral aneurysms in human immunodeficiency virus (HIV) positive children are presented. To our knowledge, only 9 patients with this association have been reported. One of our patients represents the first report of a patient with an aneurysm associated with varicella-zoster vasculitis. One patient presented with a subarachnoid hemorrhage, Hunt-Hess grade IV, and posed difficult surgical management. The other patient suffered a cerebral infarct with a resulting hemiparesis. The first patient had a ventriculostomy placed, initially improved, and subsequently died from rebleeding. The second patient improved with medical management. AIDS arteriopathy, and specifically fusiform aneurysms, are being increasingly reported. The various presentations of this surgically challenging entity in light of other AIDS-related syndromes pose difficult management decisions. On occasion, the intracranial aneurysm may be the initial form of presentation as was present in our first patient.
Basilar Artery Perforation as a Complication of Endoscopic Third Ventriculostomy
Authors: Abtin Keyvan , Thompson B. Gregory , Walker Marion L.
Published: April 2003

The morbidity and mortality associated with third ventriculostomy has decreased significantly over the past 75 years since its introduction by Walter Dandy. Now more commonly performed using an endoscopic method, the significant morbidity of third ventriculostomy has dropped to approximately 5%; essentially that associated with ventriculoscopy in general. However, the possible complication of massive subarachnoid hemorrhage resulting from perforation of the basilar artery or its branches in the course of fenestration of the floor of the third ventricle has only recently been reported. In our case, subsequent to a vascular injury, a pseudoaneurysm developed at the site of vascular perforation, which was then appropriately controlled. The patient has since made a full recovery. Our goal is to remind the endoscopist of this unusual complication and to discuss our management strategies.
MRI Features of Intracranial and Spinal Ependymomas
Authors: Lefton Daniel R. , Pinto Richard S. , Martin Steven W.
Published: April 2003

Intracranial and intraspinal ependymomas are uncommon tumors of the central nervous system. These tumors have a variety of imaging characteristics, some of which are fairly specific for ependymoma. We discuss the MRI features of ependymomas for each of the typical locations within the neuraxis, and provide MR imaging examples.
Effects of Proteins, Blood Cells and Glucose on the Viscosity of Cerebrospinal Fluid
Authors: Bloomfield I.G. , Johnston I.H. , Bilston L.E.
Published: April 2003

It has long been assumed that cerebrospinal fluid (CSF) is a newtonian fluid with viscosity similar to water, yet high protein content, has been postulated to increase the viscosity of CSF in vivo. Such an increase in viscosity may have serious implications for the effectiveness of surgical shunts implanted to re-establish the CSF flow in cases of abnormal CSF circulation. In this study, glucose content, total protein content and blood cell count in the CSF of 23 patients undergoing brain surgery were measured. Viscosity measurements were performed on duplicate CSF samples over a range of shear strain rates of 25–1,460 s–1. The results indicated that high protein or high cell concentration in CSF does not significantly affect the viscosity of the cerebral fluid at those shear rates. CSF is clearly newtonian, and its viscosity at 37°C is in the range of 0.7–1 mPa·s.
Focal Cortical Dysplasia with Glioproliferative Changes Causing Seizures: Report of 3 Cases
Authors: Madsen Joseph R. , Vallat Anne-Valérie , Poussaint Tina Young , Scott R. Michael , De Girolami Umberto , Anthony Douglas C.
Published: April 2003

In contrast to neoplasia, lesions of focal cerebral dysplasia are thought to be completed developmental processes of abnormal neuronal migration. We present three children with seizures resulting from brain lesions which pathologically demonstrate regions of both clearcut focal cortical dysplasia and also hypercellularity and monomorphism typical of proliferative lesions such as low grade glial tumor. These cases suggest the existence of a distinct subgroup of patients with prominent glioproliferative changes in association with focal cortical dysplasia, challenging the conventional dichotomy between dysplastic and proliferative categories of brain lesions. Recognition of patients with dual pathology may be of practical as well as theoretical importance.