Surgical Treatment for Empty Nose Syndrome Using Autologous Dermal Fat: Evaluation of Symptomatic Improvement.

Background: Empty nose syndrome (ENS) is caused by nasal turbinate surgery. The standard treatment for ENS is an inferior meatus augmentation procedure (IMAP) in which autologous tissue such as auricular cartilage, rib cartilage, or artificial material is transplanted into the nasal cavity. However, some challenges like a very small auricular cartilage are associated with these autologous tissue types. Moreover, since using rib cartilage is a highly invasive technique, the scar on the chest from where the harvesting is done is easily visible, and the artificial material is susceptible to infection. We used autologous dermal fat (ADF) in IMAPs in our study for the following reasons: the quantity of ADF could be increased or reduced as needed, ADF is considered a safer option than rib cartilage because it is harvested from superficial tissue, it is superior in terms of cosmetic appearance to harvested rib cartilage, and it has a lower risk of infection than any artificial material.Objective: The purpose of our study was to investigate the efficacy and safety of IMAPs using ADF.Methods: We included nine patients with ENS who underwent an IMAP using ADF. The patients' backgrounds and responses to the Empty Nose Syndrome 6-Item Questionnaire (ENS6Q) were recorded. Changes in each item of the ENS6Q before and after surgery (up to 3 months) were analyzed.Results: The postoperative ENS6Q total score and parameters were significantly better than their preoperative counterparts. Nasal dryness improved slightly less than other symptoms. There were no complications.Conclusions: The IMAP using ADF was effective in improving ENS symptoms; however, some physiological functions were difficult to improve, and dryness persisted. Autologous dermal fat is larger than auricular cartilage, less invasive than rib cartilage, and has a lower risk of infection than artificial material.

Cell cycle phenotype-based optimization of G2-abrogating peptides yields CBP501 with a unique mechanism of action at the G2 checkpoint.

Cell cycle G(2) checkpoint abrogation is an attractive strategy for sensitizing cancer cells to DNA-damaging anticancer agent without increasing adverse effects on normal cells. However, there is no single proven molecular target for this therapeutic approach. High-throughput screening for molecules inhibiting CHK1, a kinase that is essential for the G(2) checkpoint, has not yet yielded therapeutic G(2) checkpoint inhibitors, and the tumor suppressor phenotypes of ATM and CHK2 suggest they may not be ideal targets. Here, we optimized two G(2) checkpoint-abrogating peptides, TAT-S216 and TAT-S216A, based on their ability to reduce G(2) phase accumulation of DNA-damaged cells without affecting M phase accumulation of cells treated with a microtubule-disrupting compound. This approach yielded a peptide CBP501, which has a unique, focused activity against molecules that phosphorylate Ser(216) of CDC25C, including MAPKAP-K2, C-Tak1, and CHK1. CBP501 is >100-fold more potent than TAT-S216A and retains its selectivity for cancer cells. CBP501 is unusually stable, enters cells rapidly, and increases the cytotoxicity of DNA-damaging anticancer drugs against cancer cells without increasing adverse effects. These findings highlight the potency of CBP501 as a G(2)-abrogating drug candidate. This report also shows the usefulness of the cell cycle phenotype-based protocol for identifying G(2) checkpoint-abrogating compounds as well as the potential of peptide-based compounds as focused multitarget inhibitors.

Relationship between brain serotonin transporter binding, plasma concentration and behavioural effect of selective serotonin reuptake inhibitors.

1. The present study was undertaken to characterise the relationship between in vivo brain serotonin transporter (SERT) binding, plasma concentration and pharmacological effect of selective serotonin reuptake inhibitors (SSRIs) in mice. Oral administration of fluvoxamine, fluoxetine, paroxetine and sertraline at pharmacologically relevant doses exerted dose- and time-dependent binding activity of brain SERT as revealed by significant increases in KD for specific [3H]paroxetine binding, and the in vivo SERT-binding potency was in the order of paroxetine>>fluoxetine, sertraline>fluvoxamine. 2. The time courses of brain SERT binding by SSRIs in mice were mostly in parallel to those of their plasma concentrations. Also, norfluoxetine (active metabolite) has been suggested to contribute largely to the long-lasting binding activity of brain SERT after the fluoxetine administration. 3. Oral administration of each SSRI suppressed significantly the marble-burying behaviour with no change in locomotor activity in mice, and the extent and time course of suppression agreed well with those of brain SERT binding. Thus, the pharmacological potencies of SSRIs in the attenuation of marble-burying behaviour correlated significantly with their brain SERT binding activities. 4. In conclusion, the present study has provided the first in vivo evidences to support that fluvoxamine, fluoxetine, paroxetine and sertraline orally administered bind to the pharmacologically relevant brain SERT in mice and that their SERT-binding characteristics is closely associated with the pharmacokinetics and inhibition of marble-burying behaviour.

Cyclopropane-based conformational restriction of histamine. (1S,2S)-2-(2-aminoethyl)-1-(1H-imidazol-4-yl)cyclopropane, a highly selective agonist for the histamine H3 receptor, having a cis-cyclopropane structure.

A series of cyclopropane-based conformationally restricted analogues of histamine, the "folded" cis-analogues, i.e., (1S,2R)-2-(aminomethyl)-1-(1H-imidazol-4-yl)cyclopropane (11), (1S,2S)-2-(2-aminoethyl)-1-(1H-imidazol-4-yl)cyclopropane (13), and their enantiomers ent-11 and ent-13, and the "extended" trans-analogues, i.e., (1R,2R)-2-(aminomethyl)-1-(1H-imidazol-4-yl)cyclopropane (12) and its enantiomer ent-12, were designed as histamine H(3) receptor agonists. These target compounds were synthesized from the versatile chiral cyclopropane units, (1S,2R)- and (1R,2R)-2-(tert-butyldiphenylsilyloxy)methyl-1-formylcyclopropane (14 and 15, respectively) or their enantiomers ent-14 and ent-15. Among the conformationally restricted analogues, the "folded" analogue 13 (AEIC) having the cis-cyclopropane structure was identified as a potent H(3) receptor agonist, which showed a significant binding affinity (K(i) = 1.31 +/- 0.16 nM) and had an agonist effect (EC(50) value of 10 +/- 3 nM) on the receptor. This compound owes its importance to being the first highly selective H(3) receptor agonist to have virtually no effect on the H(4) subtype receptor. These studies showed that the cis-cyclopropane structure is very effective in the conformational restriction of histamine to improve the specific binding to the histamine H(3) receptor.

In vitro and ex vivo effects of a selective nociceptin/orphanin FQ (N/OFQ) peptide receptor antagonist, CompB, on specific binding of [3H]N/OFQ and [35S]GTPgammaS in rat brain and spinal cord.

1. A novel selective nociceptin/orphanin FQ (N/OFQ) peptide receptor antagonist, 1-[(3R,4R)-1-cyclooctylmethyl]-3-hydroxymethyl-4-piperidyl)-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one (CompB), inhibited specific binding of [(3)H]N/OFQ to crude membranes from the rat brain and spinal cord in a concentration-dependent manner and their K(i) values were 7.11 and 4.02 nM, respectively. Rosenthal analysis indicated that there was a significant increase in the K(d) value for [(3)H]N/OFQ binding in the brain and spinal cord in the presence of CompB (10 nM). 2. There was a dose-dependent increase in K(d) values for [(3)H]N/OFQ binding in the brain and spinal cord following i.v. injection of CompB at relatively low doses (0.69-6.88 micro mol kg(-1)), compared with the control values. In the spinal cord, enhancement with each dose was constantly greater and the duration of enhancement (6.88 micro mol kg(-1)) was significantly longer. 3. The degree of increase in K(d) values for [(3)H]N/OFQ binding after i.v. injection of CompB (6.88 micro mol kg(-1)) was significantly larger in the lumbar region of the spinal cord compared to other regions. 4. CompB (0.1, 0.3 micro M) shifted the concentration-effect curves of N/OFQ-stimulated [(35)S]GTPgammaS binding in the brain and spinal cord to the right. 5. The i.v. injection of CompB (6.88 micro mol kg(-1)) significantly suppressed the N/OFQ-stimulated [(35)S]GTPgammaS binding in the rat spinal cord and shifted the concentration-effect curve to the right, while it produced little inhibitory effect in the brain. The present study has shown that CompB may exhibit pharmacological effects through a predominant blockade of N/OFQ peptide receptors in the spinal cord under in vivo conditions.

Different distribution of morphine and morphine-6 beta-glucuronide after intracerebroventricular injection in rats.

(1) We investigated the distribution of morphine and morphine-6beta-glucuronide (M6G) in the brain and spinal cord after intracerebroventricular (i.c.v.) injection of each drug in rats. (2) The cerebrospinal fluid (CSF) concentration of M6G was 5-37 times greater than that of morphine 10, 60 and 120 min after the i.c.v. injection. The apparent elimination clearance of M6G from the CSF was 10 times lower than that of morphine. (3) The intrathecal CSF concentration of M6G measured by the microdialysis method was 29-79 times greater than that of morphine, and M6G was rapidly distributed into the intrathecal space after the i.c.v. injection. (4) M6G was detected in the cerebrum, brainstem, cerebellum and spinal cord at concentrations 2-21 times higher than morphine after the i.c.v. injection of each drug. The distribution volume of M6G in rat brain slices was three times lower than that of morphine, and close to the extracellular fluid space in the brain regions corresponding to the vicinity of the opioid receptors. (5) These brain distribution characteristics of M6G, namely, low clearance from the central nervous system, localization in the extracellular fluid and rapid distribution into the intrathecal space, may contribute to the potent analgesic effect of M6G after i.c.v. injection.

Long-acting analogue of vasoactive intestinal peptide, [R15, 20, 21, L17]-VIP-GRR (IK312532), protects rat alveolar L2 cells from the cytotoxicity of cigarette smoke.

Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) act as neurotransmitters in numerous biological responses. We previously reported that the replacement of Lys by Arg, and Met by Leu in VIP (IK312532; [Arg15, 20, 21, Leu17]-VIP) resulted in a significant improvement in metabolic stability and biological activity. In the present study, we investigated the effect of VIP and its related peptides including long-acting VIP derivative (IK312532) and PACAP27 on the cytotoxicity of cigarette smoke extract (CSE), a causative factor of chronic obstructive pulmonary disease (COPD), in rat alveolar L2 cells. RT-PCR displayed the dominant expression of mRNA for the VIP-specific VPAC2 receptor in L2 cells, and VIP and the related peptides showed the specific binding activity and potent stimulation of adenylate cyclase. CSE at a concentration of 0.1% or higher induced significant apoptotic death of L2 cells. Interestingly, the addition of neuropeptides at a concentration of 10(-11) M or higher in L2 cells with CSE (0.25%) resulted in significant attenuation of cell death with the deactivation of CSE-evoked caspase-3 activity. IK312532 was much stable against the enzymatic digestion compared to VIP, and the protective effect of IK312532 was 1.6-fold higher than that of VIP. Taken together with our previous report showing that IK312532 has long-acting relaxant activity in the lung, IK312532 may be a potential candidate for drug treatment of asthma and COPD.

Pharmacological effects and lung-binding characteristics of a novel VIP analogue, [R15, 20, 21, L17]-VIP-GRR (IK312532).

A novel VIP derivative, [R15, 20, 21, L17]-VIP-GRR (IK312532), relaxed potently the carbachol-induced contraction of guinea-pig isolated trachea with longer duration than that induced by VIP. IK312532 competed with [125I]VIP for the binding sites in the rat lung in a concentration-dependent manner. There was considerable decrease in specific [125I]VIP binding in each lobe of right and left lung 0.5 h after the intratracheal administration of IK312532 (50 microg/rat) as dry powder inhaler (DPI). Rosenthal analysis revealed that the administration of IK312532 (50 and 100 microg/rat)-DPI brought about a significant decrease of maximal number of binding sites (Bmax) for specific [125I]VIP binding in anterior and posterior lobes of rat right lung, suggesting a significant occupancy of lung VIP receptors. This effect by IK312532 in the posterior lobe of the right lung was dose-dependent and lasted until at least 2 h after the intratracheal administration. Furthermore, the antigen-evoked infiltration of granulocytes in the rat bronchiolar mucosa was markedly suppressed by the intratracheal administration of IK312532 (50 microg/rat)-DPI. In conclusion, the present study has shown that IK312532 exhibits long-lasting relaxation of tracheal smooth muscles and that the intratracheal administration of this peptide exerts a significant occupancy of lung VIP receptors as well as a suppression of the antigen-evoked infiltration of granulocytes in the bronchiolar mucosa. Thus, the formulation of IK312532 as DPI may be a pharmacologically useful drug delivery system for the therapy of pulmonary diseases such as asthma.

Effects of polychlorinated biphenyls, kanechlor-500, on serum thyroid hormone levels in rats and mice.

Effects of a commercial polychlorinated biphenyls mixture, Kanechlor-500 (KC500), on the levels of serum thyroid hormones such as total thyroxine (T4) and triiodothyronine (T3) were examined comparatively in male Wistar rats and ddy mice. Serum T4 levels were significantly decreased in both rats and mice 4 days after a single ip injection of KC500 (100 mg/kg body weight), whereas decreased levels of T3 were observed in mice but not in rats. In addition, no significant change in the level of serum thyroid stimulating hormone was observed in either rats or mice. Hepatic UDP-glucuronosyltransferases (UDP-GTs) UGT1A1 and UGT1A6, which efficiently mediate glucuronidation of T4 and promote the excretion of the hormones, were induced by KC500 in rats but not in mice. Hepatic microsomal cytochrome P450 (P450) content and the microsomal activity for 7-ethoxy-, 7-pentoxy-, and 7-benzoyloxy-resorufin dealkylations were significantly increased by KC500 in both rats and mice, although the magnitude of increase in the enzyme activities was higher in rats than in mice. The difference in the increase in the activity of microsomal enzymes, including UDP-GT and P450, between KC500-treated rats and mice was not correlated with that in the level of hepatic methylsulfonyl-PCB metabolites. In the present study, we found for the first time that the decrease in serum T4 levels by KC-500 in mice occurred without increase in hepatic UDP-GTs, UGT1A1 and UGT1A6, responsible for T4 glucuronidation. The present findings further suggested that although the decrease in serum T4 levels in KC500-treated rats would occur at least in part through the induction of the UDP-GTs, it might not be dependent on only the increase in the enzymes.

A possible mechanism for decrease in serum thyroxine level by polychlorinated biphenyls in Wistar and Gunn rats.

We have previously demonstrated that in mice, the decrease in serum thyroxine (T(4)) level by polychlorinated biphenyls (PCBs) occurs without an increase in the UDP-glucuronosyltransferase (T(4)-UDP-GT) for T(4) glucuronidation, although the PCB-induced decrease in rats is generally thought to occur through induction of T(4)-UDP-GT, UGT1A1, and UGT1A6. In the present study, to further clarify the relationship between the decrease in serum T(4) level and the increase in UGT1A activity by PCB in rats, we examined the relationship using Wistar rats and Gunn rats, a mutant strain of Wistar rats deficient in UGT1A isoforms. The serum total T(4) level was markedly decreased not only in the Wistar rats but also in the Gunn rats 4 days after treatment with a PCB, Kanechlor-500 (KC500, 100 mg/kg) or 2,2',4,5,5'-pentachlorobiphenyl (PentaCB, 112 mg/kg), and there was no significant difference in magnitude of the decrease between the two rat strains. At the same time, the level and activity of T(4)-UDP-GT were significantly increased by treatment with either KC500 or PentaCB in Wistar rats but not in Gunn rats. In addition, no significant change in the level of serum total triiodothyronine (T(3)) and thyroid-stimulating hormone by the KC500 treatment was observed in either Wistar or Gunn rats. Furthermore, significant decrease in the activity of hepatic type-I deiodinase, which mediates the deiodization of T(4) and T(3), by treatment with KC500 or PentaCB was observed in both Wistar and Gunn rats. From the serum of KC500- or PentaCB-treated Wistar and Gunn rats, mono- and di-hydroxylated PCB metabolites, which would bind to T(4) binding serum protein (transthyretin), were detected. In conclusion, the present results suggest that the decrease in serum total T(4) level by either KC500 or PentaCB in Gunn rats was not dependent on the increase in hepatic T(4)-UDP-GT activity. The findings further suggest that the PCB-mediated decrease in serum T(4) level might occur, at least in part, through formation of the hydroxylated PCB metabolites. Furthermore, even in Wistar rats, the PCB-mediated decrease in serum T(4) level might occur not only through the increase in hepatic T(4)-UDP-GT but also via formation of hydroxylated PCB metabolites.

Alpha-helical structure in the C-terminus of vasoactive intestinal peptide: functional and structural consequences.

The conformational properties of vasoactive intestinal peptide (VIP) include the N-terminal randomized structure and the C-terminal long alpha-helical structure. We have previously observed that the N-terminal random coil structure plays a crucial role in the receptor-selectivity. Here, to clarify how the formation of the alpha-helix plays a role in its biological functions, we chemically synthesized VIP analogues modified at the C-terminus, mid-chain, and N-terminus of the alpha-helical region, and evaluated the relationship between their alpha-helical contents and their biological activities including relaxant effects on murine stomach and receptor-binding activities. VIP and VIP-(1-27) showed equipotent biological activities with 48% and 50% alpha-helical content, respectively, each of which corresponds to 14 amino acid residues. VIP-(1-26) was 10% and threefold less potent in relaxant and binding activities, respectively, compared with VIP, and its 49% alpha-helical content resulted in 13 residues involved in the alpha-helix. Further truncation from 25 to 21 resulted in decrease in the alpha-helical content from 43% to 29%, corresponding residues from 11 to 6, the relaxant activity from 72% to 4%, and the affinity to the membrane from 60-fold to over 10(4)-fold less potency. In addition, disruption of the mid-chain and the N-terminus in the alpha-helical stretch by oxidation of Met(17) and deletion of Thr(11) also inhibited biological activities. These findings suggest that the presence of alpha-helical structure forming in 14 amino acid residues between position 10 and 23 in VIP is essential to its biological functions and the C-terminal amino acid residues between position 24 and 27 are requisite for this alpha-helical formation.

Blood-brain permeability of [3H]-(3-methyl-His2)thyrotropin-releasing hormone (MeTRH) in mice: effects of TRH and its analogues.

The present study was undertaken to characterize the transport of (3-methyl-His(2)) thyrotropin-releasing hormone ([(3)H]MeTRH) across the blood-brain barrier in mice and the effects of thyrotropin-releasing hormone (TRH) and its analogues (taltirelin and montirelin) on the transport and brain distribution. Integration plot analysis was used to calculate the influx clearance (CL(in)) of [(3)H]MeTRH after intravenous (i.v.) injection in mice. Furthermore, the capillary depletion method was performed to determine whether [(3)H]MeTRH crossed the blood-brain barrier. The effects of TRH and its analogues on the brain distribution of [(3)H]MeTRH were also examined by co-injection with the radioligand. The brain distribution of [(3)H]MeTRH and [(14)C]sucrose increased with the time after i.v. injection in mice, and the level of [(3)H]MeTRH was significantly higher than that of [(14)C]sucrose 5 min after the injection. The CL(in) value of [(3)H]MeTRH was significantly higher than that of [(14)C]sucrose, and the value of [(3)H]MeTRH was reduced by co-injection with unlabeled MeTRH. Also, capillary depletion showed that [(3)H]MeTRH was distributed largely in the brain parenchyma and this distribution was significantly inhibited by co-injection of TRH and montirelin but not taltirelin. The present study indicates that the transport of [(3)H]MeTRH into the brain may be via a saturable process.

In vivo identification and characterization of binding sites for selective serotonin reuptake inhibitors in mouse brain.

The present study was undertaken to identify and characterize in vivo binding sites of selective serotonin reuptake inhibitors (SSRIs) in the mouse brain by using [3H]paroxetine as radioligand. Relatively higher concentration of [3H]paroxetine was detected in the whole brain (minus cerebellum) than in the plasma of mice after the i.v. injection of the radioligand, and the half-life (t1/2) of elimination was much slower. The in vivo specific [3H]paroxetine binding in the mouse brain after the i.v. injection was defined as the difference of particulate-bound radioactivity between the whole brain and cerebellum, and it was dose-dependently attenuated by oral or intraperitoneal administration of fluoxetine (8.68-116 micromol/kg). Furthermore, oral administration of fluvoxamine, fluoxetine, paroxetine and sertraline at the pharmacologically relevant doses reduced significantly (25-94%) in vivo specific [3H]paroxetine binding in the cerebral cortex, striatum, hippocampus, thalamus and midbrain of mice, and their significant decreases were observed up to at least 8 h (fluvoxamine), 24 h (fluoxetine), and 12 h (paroxetine and sertraline) later. The value of area under the curve (AUC) for decrease in [3H]paroxetine binding vs. time in each brain region was largest for fluoxetine among these SSRIs, due to the relatively longer-lasting occupation of brain serotonin transporter. The AUC value in mouse brain after oral administration of each SSRI was 1.2-3.2 times greater in the thalamus and midbrain than in the cerebral cortex, striatum and hippocampus. Thus, the present study has revealed that [3H]paroxetine may be a suitable radioligand for in vivo characterization of brain binding sites and pharmacological effects of SSRIs.

In vivo receptor binding of benidipine and amlodipine in mesenteric arteries and other tissues of spontaneously hypertensive rats.

The present study was undertaken to characterize the in vivo 1,4-dihydropyridine (DHP) receptor binding of long-acting 1,4-DHP calcium channel antagonists in the mesenteric artery and other tissues of SHR. In vivo specific binding of (+)-[3H]PN 200-110 in the SHR mesenteric artery was significantly (36.6-49.7 %) reduced 1-8 h after oral administration of benidipine (1.84 micromol/kg). A greater reduction in (+)-[3H]PN 200-110 binding in the mesenteric artery was observed at a higher dose (5.53 micromol/kg) of this drug. This dose of benidipine also reduced significantly the in vivo specific (+)-[3H]PN 200-110 binding in the aorta but not in the myocardium and cerebral cortex. Following oral administration of amlodipine (17.6 micromol/kg), a significant (51.7-94.2 %) reduction in (+)-[3H]PN 200-110 binding was seen at 1-18 h in the mesenteric artery and at 1-12 h in the aorta. Only a slight reduction in myocardial and cerebral cortical (+)-[3H]PN 200-110 binding was seen following amlodipine administration. In contrast, oral administration of nifedipine (28.9 micromol/kg) reduced markedly in vivo (+)-[3H]PN 200-110 binding in all the tissues of SHR at 1-6 h, and the degree and time-course of the reduction did not differ significantly among the tissues. The area under the curve (AUC) for the receptor occupancy vs time was calculated from the reduction rate (%) of in vivo specific (+)-[3H]PN 200-110 binding. The ratios of the AUCmesenteric artery to AUCaorta or AUCmesenteric artery to AUCmyocardium after oral administration of benidipine and amlodipine were greater than the corresponding value for nifedipine. The degree and time-course of arterial receptor occupancy by benidipine and amlodipine agreed well with those of their hypotensive effects in the conscious SHR. In conclusion, the present study demonstrates that benidipine and amlodipine may occupy, in a more selective and sustained manner, 1,4-DHP receptors in arterial tissues than in other tissues of SHR, and thus, such receptor binding specificity may be responsible for the long-lasting hypotensive effects of these drugs.

Neuroprotective effect and brain receptor binding of taltirelin, a novel thyrotropin-releasing hormone (TRH) analogue, in transient forebrain ischemia of C57BL/6J mice.

Thyrotropin-releasing hormone (TRH) and some of its stable analogues have been shown to improve neurologic dysfunctions such as brain trauma in both animals and humans. Our previous study revealed that taltirelin, a novel orally active TRH analogue, binds to rat brain TRH receptors in vivo. The present study was undertaken to investigate whether taltirelin has neuroprotective effects in transient brain ischemia of C57BL/6J mice induced by bilateral carotid artery occlusion (2VO). Neuronal cell density in the hippocampal CA1 region of C57BL/6J mice was significantly (39.9%) decreased 1 week after 2VO-reperfusion, compared to the case of the sham group, and this reduction of hippocampal neuronal density was significantly suppressed by an intravenous (i.v.) injection of taltirelin (0.3 mg/kg). The i.v. injection of taltirelin at this dosage produced a significant increase in the dissociation constant (Kd) of specific [3H]MeTRH binding in sham and 2VO-reperfusion groups (33.6 and 51.4%, respectively) compared with the vehicle-treated group. These results indicate that the intravenously injected taltirelin bound to TRH receptors in the ischemic brain. There was little difference in the brain-to-plasma concentration ratio (Kp) of [14C]sucrose between the sham and 2VO groups of C57BL/6J mice, indicating that the tight junction of the blood-brain barrier may be intact in the ischemic brain. In conclusion, the study has shown that taltirelin may have a significant neuroprotective effect on the ischemic brain.

Structure-activity relationship of synthetic truncated analogues of vasoactive intestinal peptide (VIP): an enhancement in the activity by a substitution with arginine.

In order to develop potent shortened analogues of vasoactive intestinal peptide (VIP), the structure-activity relationship of C-terminally truncated analogues of VIP was investigated by examining the binding activity to rat lung VIP receptors and relaxation of smooth muscle in isolated mouse stomach. VIP(1-27) showed VIP receptor binding activity comparable to that of VIP but the activity of VIP(1-26) was reduced to one-third of VIP. The receptor binding activity of VIP(1-26) to VIP(1-23) was reduced in proportion to the decrease in amino acid residues. There was a significant correlation between the number of amino acid residues and VIP receptor binding activities of VIP and its C-terminally truncated analogues. VIP(1-22) and VIP(1-21) exhibited little binding activity even at high concentrations, suggesting the requisite of 23 amino acid residues as the minimal essential sequence for the conservation of VIP receptor binding activity. The chemical modification of VIP(1-23) generated a potent analogue, [Arg(15, 20, 21), Leu(17)]-VIP(1-23), that displayed a 22-fold higher receptor binding activity and 1.6-fold more potent relaxation of mouse stomach than VIP(1-23) did. In conclusion, it was shown that [Arg(15, 20, 21), Leu(17)]-VIP(1-23) could be a relatively potent and stable agonist of VIP receptors. The present study has provided further insight into the structure-activity relationship of VIP to generate novel shortened VIP analogues having a high affinity to VIP receptors and potent pharmacological activity.

Studies on the transport of thyrotropin-releasing hormone (TRH) analogues in Caco-2 cell monolayers.

The transport mechanisms of thyrotropin-releasing hormone (TRH) and its pharmacologically active analogues ((3-methyl-His(2))TRH (MeTRH), taltirelin, montirelin, azetirelin) across Caco-2 cell monolayers were characterized. The results of kinetic analysis showed a linear relationship between the concentration (over the range 0.5-10 mM) and apical-to-basolateral transport rate of these agents. The permeability coefficients (P(app)) of these agents were not substantially different from each other, and their P(app) ratios of the basolateral-to-apical over the apical-to-basolateral transport were close to one (0.73-1.23). The cellular transport of [(3)H]MeTRH at low concentrations (3-15 nM) showed a linear relationship between the concentration and transport rate. The transport of [(3)H]MeTRH in Caco-2 cell monolayers was neither affected by TRH nor TRH analogues, and there was little difference in P(app) values between [(3)H]MeTRH and [(14)C]mannitol. The cell-per-medium ratio of [(3)H]MeTRH in the cellular uptake experiment was similar to the value of [14C]mannitol. A large excess of TRH and MeTRH did not significantly influence cell-per-medium ratios of [(3)H]MeTRH in Caco-2 cell monolayers. The k'(IAM) value, which represents lipophilicity, was decreased in the following order: montirelin > taltirelin > TRH > azetirelin, and the values varied from 0.234 to 1.028. These results indicate that a paracellular passive diffusion may be the major route for the transport of TRH and its analogues in Caco-2 cell monolayers.

[Metabolism of 2,3,3',4,4'-pentachlorobiphenyl in hamsters].

The in vivo metabolism of 2,3,3',4,4'-pentachlorobiphenyl (CB105) was studied in hamsters and the effect of cytochrome P450 inducers, phenobarbital (PB) and 3-methylcholanthrene (MC) on its metabolism was compared to rats. After administration of CB105 intraperitoneally at a dose of 3 mg/body, four metabolites, named M-1, M-2, M-3 and M-4, were detected in 5 days-feces of all groups and the formation ratio of the metabolites M-1-M-4 was 1:39:84:0.2 in untreated hamsters and 1:19:6.7:0.7 in untreated rats. On the basis of the mass spectra of four synthetic authentic compounds and the retention times on DB-1 and MPS50 columns, M-1, M-2, M-3 and M-4 were identified as 4'-hydroxy-2,3,3',4,5'-PenCB, 5'-hydroxy-CB105, 5-hydroxy-CB105 and 4-hydroxy-2,3,3',4',5-PenCB, respectively. The pretreatment of PB and MC resulted in about 2-fold fecal excretion of four metabolites in hamsters and in about 3-fold in rats. Of four metabolites, only M-4 were detected in the serum at 5 days after CB105 administration and the concentration was 0.39 microgram/ml of hamster serum and 0.28 microgram/ml of rat serum. In hamsters, the concentration of M-4 was increased to 1.8-fold of untreated animals by PB treatment and 2.6-fold by MC treatment. On the other hand, the treatment of rats with PB and MC did not show such an increase of serum M-4. These results suggested that the hamster oxidized 2,3,4-trichloro-substituted benzene ring predominantly rather than 3',4'-dichloro-substituted benzene ring differently from the rat and that M-4 formed in hamster liver distributed to the blood and retained there to a considerable extent in comparison with that formed in rat liver.

The decrease in level of serum thyroxine by 2,2',4,5,5'-pentachlorobiphenyl in rats and mice: no correlation with formation of methylsulfonyl metabolites.

A relationship between formation of methylsulfonyl (MeSO2) metabolites of 2,2',4,5,5'-pentachlorobiphenyl (PentaCB) and decrease in serum thyroxine (T4) level was examined in the rats and mice after a single i.p. injection of PentaCB (342 micromol/kg body weight). In either rats or mice, levels of the 3- and 4-MeSO2 metabolites of PentaCB in the liver and feces increased in a time-dependent fashion up to 8 days after PentaCB-treatment. However, there was a marked difference between rats and mice in the amount of the metabolites formed, and the cumulative amount of the either MeSO2 metabolite for 8 days after PentaCB treatment in the liver was 4 to 15 times higher in mice than in rats. On the other hand, a 40 to 60% decrease in level of serum total T4 occurred in both rats and mice at 1 day after PentaCB treatment, and the decrease was retained up to 8 days after PentaCB treatment. Thus, there was a marked difference between rats and mice in the formation of MeSO2 metabolites from PentaCB but not a significant difference between rats and mice in PentaCB-induced decrease in the level of serum total T4, indicating that PentaCB-induced decrease in the level of serum total T4 is not necessarily dependent on the MeSO2 metabolites formed.

In vivo measurement of 1,4-dihydropyridine receptors in mesenteric arteries of spontaneously hypertensive rats and effect of nifedipine and cilnidipine.

The present study was undertaken to measure 1,4-dihydropyridine (DHP) receptor binding sites in vivo in the mesenteric artery and other tissues of spontaneously hypertensive rats (SHR) and to examine the effect of nifedipine and cilnidipine. Specific in vivo binding of (+)-[3H]PN 200-110 in the SHR mesenteric artery was dose dependently reduced by oral administration of nifedipine at relatively low doses. Oral administration of cilnidipine (6.09 micromol/kg) significantly reduced the specific in vivo binding of (+)-[3H]PN 200-110 in the mesenteric artery, aorta, and myocardium. A significant reduction in (+)-[3H]PN 200-110 binding was seen at 1-12 h in the mesenteric artery and at 1-7 h in the aorta and myocardium. In contrast, oral administration of nifedipine (28.9 micromol/kg) markedly reduced in vivo (+)-[3H]PN 200-110 binding in all tissues of SHR at 1-6 h, and the degree and time course of the reduction did not differ much among the tissues. The area under the curve (AUC) for receptor occupancy vs. time was calculated from the reduction rate (%) of specific in vivo (+)-[3H]PN 200-110 binding. The ratio (1.4 or 1.7) of the AUC(mesenteric artery) to AUCaorta or AUCmyocardium after oral administration of cilnidipine was greater than the corresponding value (1.1) for nifedipine. In conclusion, the present study demonstrates that cilnidipine, but not nifedipine, may occupy 1,4-DHP receptors in the small artery in a more selective and sustained manner than in other tissues of SHR, and thus such receptor binding specificity may be responsible for the long-lasting hypotensive effect of this drug.