Gastric motor effects of peptide and non-peptide ghrelin agonists in mice in vivo and in vitro

BACKGROUND AND AIMS

The gastroprokinetic activities of ghrelin, the natural ligand of the growth hormone secretagogue receptor (GHS-R), prompted us to compare the effect of ghrelin with that of synthetic peptide (growth hormone releasing peptide 6 (GHRP-6)) and non-peptide (capromorelin) GHS-R agonists both in vivo and in vitro.

METHODS

In vivo, the dose dependent effects (1-150 nmol/kg) of ghrelin, GHRP-6, and capromorelin on gastric emptying were measured by the 14C octanoic breath test which was adapted for use in mice. The effect of atropine, N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME), or D-Lys3-GHRP-6 (GHS-R antagonist) on the gastroprokinetic effect of capromorelin was also investigated. In vitro, the effect of the GHS-R agonists (1 microM) on electrical field stimulation (EFS) induced responses was studied in fundic strips in the absence and presence of L-NAME.

RESULTS

Ghrelin, GHRP-6, and capromorelin accelerated gastric emptying in an equipotent manner, with bell-shaped dose-response relationships. In the presence of atropine or l-NAME, which delayed gastric emptying, capromorelin failed to accelerate gastric emptying. D-Lys3-GHRP-6 also delayed gastric emptying but did not effectively block the action of the GHS-R agonists, but this may be related to interactions with other receptors. EFS of fundic strips caused frequency dependent relaxations that were not modified by the GHS-R agonists. L-NAME turned EFS induced relaxations into cholinergic contractions that were enhanced by ghrelin, GHRP-6, and capromorelin.

CONCLUSION

The 14C octanoic breath test is a valuable technique to evaluate drug induced effects on gastric emptying in mice. Peptide and non-peptide GHS-R agonists accelerate gastric emptying of solids in an equipotent manner through activation of GHS receptors, possibly located on local cholinergic enteric nerves.

Classification of abomasal displacement in cows according to histopathology of the liver and clinical chemistry

Histopathological features of livers and blood chemical values in cows with abomasal displacement were investigated. Liver biopsy samples were collected during redressment operations in 92 cows with abomasal displacement, and the samples were stained with haematoxylin and eosin or periodic acid Schiff (PAS). Blood was collected for chemical tests. Livers were histopathologically divided into the following four types: normal histology cases (21%), fatty degeneration cases (36%), cloudy swelling cases (19%) and fatty degeneration cases with cloudy swelling (24%). The number of PAS-positive samples was significantly higher in the normal histology group and significantly lower in the severe fatty degeneration group and severe cloudy swelling group. Cows with fatty degeneration had significantly higher levels of serum 3-hydroxybutyric acid, non-esterified fatty acid and aspartate aminotransferase than did those with cloudy swelling or normal histology. The results indicate that the morbid conditions of cows with abomasal displacement can be classified into four types.

False positive uptake of metaiodobenzylguanidine in hepatocellular carcinoma

We present the case of a patient who showed increased accumulation of (123)I-metaiodobenzylguanidine (MIBG) in hepatocellular carcinoma, leading to a false presumptive diagnosis of intrahepatic neuroendocrine tumour. The increase in uptake was not seen on images obtained 4 h after tracer injection but was evident on those taken after 24 h, suggesting slower washout from the liver tumour than from non-tumoural liver parenchyma. Our observations indicate that a non-neuroendocrine malignant tumour may exhibit high accumulation of MIBG associated with prolonged retention.

Potentiation of motilin-induced contraction by nitric oxide synthase inhibition in the isolated chicken gastrointestinal tract

The present experiments were designed to determine whether or not endogenous nitric oxide (NO) modifies the contractile response to chicken motilin (ch-MT) in the gastrointestinal (GI) tract (proventriculus and small intestine) of the chicken. ch-MT (1 nmol L(-1)-1 micromol L(-1)) caused contractions of longitudinal muscle strips of the proventriculus through both myogenic and neurogenic (mostly cholinergic) mechanisms. On the other hand, ch-MT (0.1 nmol L(-1)-100 nmol L(-1)) contracted the small intestine (duodenum, jejunum and ileum) only through a myogenic mechanism. L-Nitroarginine methylester (L-NAME) potentiated, and L-arginine inhibited, the ch-MT- induced contraction without affecting the responsiveness of acetylcholine (ACh) or 5-hydroxytryptamine in the proventriculus. Electrical field stimulation (EFS)- and 1,1-dimethyl-4-phenylpiperazinium (DMPP)- induced contractions were also potentiated by L-NAME. The potentiation by L-NAME was prevented by L-arginine but not by D-arginine. However, in the presence of atropine or tetrodotoxin, neither L-NAME nor L-arginine modified the responses to ch-MT and DMPP. In contrast to the proventriculus, L-NAME and L-arginine were both ineffective in modifying the ch-MT-induced contraction in the small intestine. These results indicate that NO synthase inhibition potentiates the contractile response of ch-MT, EFS and DMPP in the chicken proventriculus through reduction of endogenous NO-mediated presynaptic inhibition on neural ACh release. However, NOS inhibition did not modify the myogenic (direct) action of ch-MT in gastric and intestinal smooth muscles of the chicken.

5-HT(7) receptor and beta(2)-adrenoceptor share in the inhibition of porcine uterine contractility in a muscle layer-dependent manner

To compare the inhibition of uterine contractility mediated by beta-adrenoceptors and 5-HT(7) receptors, the effects of catecholamines and 5-HT on spontaneous contractions were examined in longitudinal and circular muscles isolated from three different regions (cornu, corpus and cervix) of the non-pregnant proestrus porcine uterus. In addition, the distribution of beta-adrenoceptors between muscle layers was characterized by means of adenylate cyclase activity assay, cyclic AMP assay and [(3)H]dihydroalprenolol binding studies. In the cornu, isoprenaline, adrenaline and noradrenaline inhibited the spontaneous contraction of longitudinal and circular muscles but longitudinal muscle was more sensitive to catecholamines than was circular muscle. The inhibitory response to isoprenaline was antagonized by propranolol (300 nM) or (+/-)-1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol (ICI 118,551; 100 nM). The rank order of potency was isoprenaline > or =adrenaline > noradrenaline. The beta(2)-adrenoceptor-selective agonist, clenbuterol, was more potent than xamoterol (beta(1)-selective) and (+/-)-4-[2-[(2-(3-chlorophenyl)-2-hydroxyethyl)amino]propyl]phenoxyacetic acid (BRL 37344; beta(3)-selective) to inhibit the spontaneous contraction of longitudinal muscles. Isoprenaline increased adenylate cyclase activity in both muscle layers, but the activity in the longitudinal muscle was greater than that in the circular muscle. Cyclic AMP production by isoprenaline was also more conspicuous in the longitudinal muscle than in the circular muscle. Although both muscle layers contained a single class of [3H]dihydroalprenolol binding sites with similar K(d) values (longitudinal muscle, 3.1+/-0.94 nM, n=4; circular muscle, 2.4+/-0.73 nM, n=4), B(max) in the longitudinal muscle (175.7+/-32.8 fmol/mg protein, n=4) was significantly higher than that in the circular muscle (53.1+/-5.1 fmol/mg protein, n=4). As previously reported [Br. J. Pharmacol. 130 (2000) 79], 5-HT also inhibited the spontaneous contraction of both muscle layers from the cornu and the 5-HT(7) receptor antagonist, 2a-[4-(4-phenyl-1,2,3,6-tetrahydropyridyl)butyl]-2a,3,4,5-tetrahydro-benzo[cd]indol-2(1H)-one (DR4004; 100 nM, n=4) blocked the 5-HT-induced inhibition of spontaneous contractions in the circular muscles, and reversed the less marked inhibition in the longitudinal muscles. In other regions of the uterus (corpus and cervix), 5-HT inhibited the spontaneous contraction of the circular muscles but contracted the longitudinal muscle strips. On the other hand, isoprenaline caused muscle layer-dependent inhibition (longitudinal muscle > circular muscle) in both regions, and the responsiveness tended to increase toward the cervix. In conclusion, beta(2)-adrenoceptors are present heterogeneously in the porcine uterus (longitudinal muscle > circular muscle) and share the inhibition of uterine contractility with 5-HT(7) receptors in a layer-dependent manner (longitudinal muscle: beta(2)-adrenoceptors, circular muscle: 5-HT(7) receptors).

Expression of CPI-17 and myosin phosphatase correlates with Ca(2+) sensitivity of protein kinase C-induced contraction in rabbit smooth muscle

1. Various smooth muscles have unique contractile characteristics, such as the degree of Ca(2+) sensitivity induced by physiological and pharmacological agents. Here we evaluated six different rabbit smooth muscle tissues for protein kinase C (PKC)-induced Ca(2+) sensitization. We also examined the expression levels of myosin light chain phosphatase (MLCP), the MLCP inhibitor phosphoprotein CPI-17, and the thin filament regulator h-calponin. 2. Immunohistochemical and Western blot analyses indicated that CPI-17 was found primarily in smooth muscle, although expression varied among different tissues. Vascular muscles contained more CPI-17 than visceral muscles, with further distinction existing between tonic and phasic subtypes. For example, the tonic femoral artery possessed approximately 8 times the cellular CPI-17 concentration of the phasic vas deferens. 3. In contrast to CPI-17 expression patterns, phasic muscles contained more MLCP myosin-targeting subunit than tonic tissues. Calponin expression was not statistically different. 4. Addition of phorbol ester to alpha-toxin-permeabilized smooth muscle caused an increase in contraction and phosphorylation of both CPI-17 and myosin light chain (MLC) at submaximal [Ca(2+)]i. These responses were several-fold greater in femoral artery as compared to vas deferens. 5. We conclude that the expression ratio of CPI-17 to MLCP correlates with the Ca(2+) sensitivities of contraction induced by a PKC activator. PKC stimulation of arterial smooth muscle with a high CPI-17 and low MLCP expression generated greater force and MLC phosphorylation than stimulation of visceral muscle with a relatively low CPI-17 and high MLCP content. This implicates CPI-17 inhibition of MLCP as an important component in modulating vascular muscle tone.

Histamine-induced vasoconstriction involves phosphorylation of a specific inhibitor protein for myosin phosphatase by protein kinase C alpha and delta isoforms

Histamine stimulus triggers inhibition of myosin phosphatase-enhanced phosphorylation of myosin and contraction of vascular smooth muscle. In response to histamine stimulation of intact femoral artery, a smooth muscle-specific protein called CPI-17 (for protein kinase C-potentiated inhibitory protein for heterotrimeric myosin light chain phosphatase of 17 kDa) is phosphorylated and converted to a potent inhibitor for myosin phosphatase. Phosphorylation of CPI-17 is diminished by pretreatment with either or GF109203x, suggesting involvement of multiple kinases (Kitazawa, T., Eto, M., Woodsome, T. P., and Brautigan, D. L. (2000) J. Biol. Chem. 275, 9897--9900). Here we purified and identified CPI-17 kinases endogenous to pig artery that phosphorylate CPI-17. DEAE-Toyopearl column chromatography of aorta extracts separated two CPI-17 kinases. One kinase was protein kinase C (PKC) alpha, and the second kinase was purified to homogeneity as a 45-kDa protein, and identified by sequencing as PKC delta. Purified PKC delta was 3-fold more reactive with CPI-17 compared with myelin basic protein, whereas purified PKC alpha and recombinant RhoA-activated kinases (Rho-associated coiled-coil forming protein Ser/Thr kinase and protein kinase N) showed equal activity with CPI-17 and myelin basic protein. inhibited CPI-17 phosphorylation by purified PKC delta with IC(50) of 0.6 microm (in the presence of 0.1 mm ATP) or 14 microm (2.0 mm ATP). significantly suppressed CPI-17 phosphorylation in smooth muscle cells, and the contraction of permeabilized rabbit femoral artery induced by stimulation with phorbol ester. GF109203x inhibited phorbol ester-induced contraction of rabbit femoral artery by 80%, whereas a PKC alpha/beta inhibitor, Go6976, reduced contraction by 47%. The results imply that histamine stimulation elicits contraction of vascular smooth muscle through activation of PKC alpha and especially PKC delta to phosphorylate CPI-17.

Clinical factors of recurrent chronic subdural hematoma

The clinical, radiological, and operative factors of recurrent chronic subdural hematoma (CSDH) were retrospectively analyzed in 116 patients with CSDH in 134 hemispheres, treated by one burr hole surgery. The correlation of recurrence was evaluated with personal and clinical factors such as age, sex, history of head injury, and interval from onset of initial symptoms to hospitalization; laboratory findings such as bleeding tendency and liver function; computed tomography (CT) findings such as hematoma density and brain atrophy; and operative findings such as additional procedures and postoperative residual air. The recurrence group (RG) included 10 hemispheres (7.5%) in 10 patients (8.6%). The interval from onset of symptoms to hospitalization was significantly shorter in the RG than in the nonrecurrence group (NRG). Headache was more frequently seen in the RG than in the NRG. Density of hematoma on CT was classified into five types: Low, iso, and high density, niveau, and mixed, and the incidence of recurrence was 0%, 2.3%, 17.2%, 12.5%, and 6.5%, respectively. Larger amounts of residual air in the postoperative hematoma cavity were associated with recurrence of CSDH. CSDH that progresses rapidly in the acute stage and appears as high density on preoperative CT is associated with a high incidence of recurrence. Intraoperative air invasion to the hematoma cavity should be avoided to prevent recurrence.

[An attempt to estimate geographical accessibility to day service facilities among the elderly with a geographical information system]

OBJECTIVE

The objective of this study was to assess inequality in geographical accessibility to day service among the elderly in a municipality using a geographical information system (GIS). We also examined problems in measuring geographical accessibility and ways to validate results.

METHODS

The target was Hachioji City. The following two data sets were constructed: a data set for day service facilities for all of Hachioji City and a data set for the people aged 65 and over, living within 1 km meshes in Hachioji City. These were integrated and displayed on a digital map with GIS software. Geographical accessibility was estimated by measuring the shortest road distance from the center point of each mesh to day service facilities.

RESULTS

There were 47 day service facilities serving Hachioji City in October, 2000 and 139 meshes that had elderly residents. Their center points were all located within Hachioji City, which was estimated to have 73,760 elderly in 2000. The mean distance from the center point of each mesh to the nearest day service facility was 1.99 km (SD = 1.75, max = 9.21, min = 0.03). The proportions of the elderly who had 5 or more facilities within 3 km and 5 km from their residence were estimated to be 57.3% and 96.4%, respectively.

CONCLUSIONS

The results of this study suggest that there is variation in geographical accessibility to day service facilities among the elderly living in a relatively large municipality. It is now necessary to examine whether the difference in geographical accessibility to day service affects the service utilization.

Muscle layer- and region-dependent distributions of oxytocin receptors in the porcine myometrium

The aim of the present study was to clarify smooth muscle- and region-dependent distributions of the oxytocin receptor that mediates oxytocin-induced contraction in the nonpregnant porcine myometrium by means of mechanical and radioligand ([3H]-oxytocin) binding studies. In Krebs solution, oxytocin (0.1-300 nM) caused concentration-dependent contractions of the cornual myometrium, and the longitudinal muscle was more sensitive than the circular muscle. [Arg8]-vasopressin and [deamino-Cys1, D-Arg8]-vasopressin also contracted the myometrium, and the order of the potency was oxytocin > [Arg8]-vasopressin > [deamino-Cys(1), D-Arg(8)]-vasopressin. Treatment with a high concentration of oxytocin selectively inhibited the contraction of oxytocin and [Arg8]-vasopressin without affecting the responses of acetylcholine and high-K+. Selective cross inhibition was also observed in the presence of a high concentration of [Arg(8)]-vasopressin. The oxytocin-induced contraction was resistant to tetrodotoxin and atropine, but was reduced by verapamil or by the removal of external Ca2+, indicating that oxytocin has a direct action on smooth muscle cells and that extracellular Ca2+ plays an important role for the contraction. In Kumagai solution, oxytocin caused contraction of the cornual longitudinal muscle (-logEC50 = 8.5) but not the circular muscle. Longitudinal muscles of other regions (corpus and cervix) were also responsive to oxytocin, but the -logEC50 value differed from region to region (cornua > corpus = cervix). On the other hand, oxytocin failed to cause contraction of the corpus and cervical circular muscles. 3H-Oxytocin bound to crude membrane preparations of the myometrium in a concentration-dependent (0.084-2.7 nM) saturable manner. Scatchard analysis of equilibrium binding data revealed the presence of a single class of binding site with an apparent dissociation constant (Kd, 1.1-1.5 nM), but receptor density (Bmax) differed in the two muscle layer types (longitudinal muscle: circular muscle = 5:1) and tended to decrease from the cornua to the cervix. In conclusion, the receptor specific for oxytocin is present in the porcine myometrium and mediates the contractile responses of both oxytocin and [Arg8]-vasopressin. The distribution of the oxytocin receptors differs according to the type of muscle layer (longitudinal muscle > circular muscle) and the region of the uterus.

Characterization of the amino acid transport of new immortalized choroid plexus epithelial cell lines: a novel in vitro system for investigating transport functions at the blood-cerebrospinal fluid barrier

PURPOSE

To establish and characterize a choroid plexus epithelial cell line (TR-CSFB) from a new type of transgenic rat harboring the temperature-sensitive simian virus 40 (ts SV 40) large T-antigen gene (Tg rat).

METHODS

Choroid plexus epithelial cells were isolated from the Tg rat and cultured on a collagen-coated dish at 37 degrees C during the first period of 3 days. Cells were subsequently cultured at 33 degrees C to activate large T-antigen. At the third passage, cells were cloned by colony formation and isolated from other cells using a penicillin cup.

RESULTS

Five immortalized cell lines of choroid plexus epithelial cells (TR-CSFB 1 approximately 5) were obtained from two Tg rats. These cell lines had a polygonal cell morphology, expressed the typical choroid plexus epithelial cell marker, transthyretin, and possessed Na+, K+-ATPase on their apical side. TR-CSFBs cells expressed a large T-antigen and grew well at 33 degrees C with a doubling-time of 35 approximately 40 hr. [3H]-L-Proline uptake by TR-CSFB cells took place in an Na+-dependent, ouabain-sensitive, energy-dependent, and concentration-dependent manner. It was also inhibited by alpha-methylaminoisobutylic acid, suggesting that system A for amino acids operates in TR-CSFB cells. When [3H]-L-proline uptake was measured using the Transwell device, the L-proline uptake rate following application to the apical side was five-fold greater than that following application to the basal side. In addition, both Na+-dependent and Na+-independent L-glutamic acid (L-Glu) uptake processes were present in TR-CSFB cells.

CONCLUSIONS

Immortalized choroid plexus epithelial cell lines were successfully established from Tg rats and have the properties of choroid plexus epithelial cells, and amino acid transport activity was observed in vivo.

Hapten-specific tolerance promoted by calcitonin gene-related peptide

Calcitonin gene-related peptide has been shown to modulate inflammatory and immune responses in various systems. Recent studies in our laboratory and colleagues have shown that intracutaneously injected calcitonin gene-related peptide impairs the induction of contact hypersensitivity in mice, and participates in the pathogenesis of failed contact hypersensitivity induction after acute, low-dose ultraviolet B radiation. In this study we investigated the ability of calcitonin gene-related peptide to induce tolerance in normal and mast cell deficient mice and we examined the extent to which calcitonin gene-related peptide contributes to the tolerance induced by acute, low-dose ultraviolet B radiation. Calcitonin gene-related peptide was injected intradermally followed by application of 2,4-dinitro-1-fluorobenzene to the injected skin surface. Tolerance was assessed by re-exposing the mice 2 wk later to a second, sensitizing dose of 2, 4-dinitro-1-fluorobenzene on uninjected skin. We found that calcitonin gene-related peptide induced tolerance to 2, 4-dinitro-1-fluorobenzene in both normal and mast cell deficient mice. Calcitonin gene-related peptide-induced tolerance was blocked by intradermal injection of a calcitonin gene-related peptide antagonist [CGRP-(8-37)] that selectively blocks the calcitonin gene-related peptide receptor. Tolerance was also abolished by intraperitoneally injected anti-interleukin-10, but not anti-tumor necrosis factor alpha, antibodies. When 2,4-dinitro-1-fluorobenzene was painted on skin into which splenic dendritic cells pretreated with calcitonin gene-related peptide had been injected, tolerance was observed. Calcitonin gene-related peptide- treated dendritic cells mixed with anti-interleukin-10 antibody prior to intradermal injection failed to promote tolerance. Finally, injection of CGRP-(8-37) into skin that was subsequently exposed to acute, low-dose ultraviolet B radiation partially prevented tolerance induced by local application of 2,4-dinitro-1-fluorobenzene. These results indicate that calcitonin gene-related peptide has the capacity to promote cutaneous tolerance through an interleukin-10-dependent mechanism. This mechanism, which does not require the participation of mast cells, contributes to the tolerance promoted by acute, low-dose ultraviolet B radiation. Thus, calcitonin gene-related peptide from cutaneous nerve endings plays a key role in the local immune aberrations caused by ultraviolet B radiation.

An anatomic examination of the suprascapular flap

To investigate the potential utility of a suprascapular flap, the authors examined dissected cadavers to identify the ramification of the suprascapular artery, and directly injected 2.5% patent blue dye to observe the distribution of its cutaneous perforators. Results indicate that a suprascapular flap is not practicable. The branching pattern of the suprascapular artery from the subclavian artery varies widely, making dissection of the vessels highly problematic. Moreover, no constant presence of cutaneous perforators from the artery could be identified in either the suprascapular fossa or the shoulder.

Change of the involvement of 5-HT3 receptor in the gastric motor stimulating actions of KW-5139 (Leu13-motilin acetate) in the recovered and post-operative periods in dogs

We have previously reported that KW-5139, a motilin analogue, evokes gastrointestinal motor stimulating action in the post-operative period as well as in the recovered period of conscious dogs. In this report, we compared the mechanisms of the KW-5139-induced contractions in the post-operative period with those in the recovered period using beagle dogs implanted force transducers in the gastric antrum, duodenum, jejunum, ileum and colon. In addition, we also examined the mechanisms of the prostaglandin F2alpha-induced contractions in both periods. The gastric contractions evoked by KW-5139 (0.5 microg kg(-1), i.v.) were inhibited by the pretreatment of ondansetron (0.1 mg kg(-1), i.v.), a 5-HT3 receptor antagonist, in the recovered period, but were not affected in the post-operative period even by higher doses of ondansetron (0.3-1 mg kg(-1), i.v.). The KW-5139-induced contractions in the small and large intestine were not inhibited by ondansetron in the both periods. The contractions evoked by KW-5139 (0.5 microg kg(-1), i.v.) in the gastric antrum, duodenum, jejunum and colon were significantly inhibited by the pretreatment with atropine (0.05 mg kg(-1), i.v.), a muscarinic receptor antagonist, in the recovered period as same extent as in the post-operative period. The contractions evoked by prostaglandin F2alpha (50 microg kg(-1), i.v.) in the any recording sites were not affected by the pretreatment with ondansetron (0.1 mg kg(-1), i.v.) in the recovered period. On the other hand, atropine (0.05 mg kg(-1), i.v.) tended to inhibit the gastric and colonic contractions. These effects of ondansetron and atropine on the prostaglandin F2alpha-induced contractions were not different between in the post-operative and recovered periods. The present results indicate that 5-HT3 receptors are involved in the KW-5139-induced motor stimulating action in the recovered period but not in the post-operative period. The mechanisms of the alteration were discussed.

Suprathreshold doses of hapten are required to induce both contact hypersensitivity and tolerance

Whereas both high (conventional) and low (optimal) doses of epicutaneously applied hapten induce contact hypersensitivity in normal mice, only conventional doses retain their capacity to induce contact hypersensitivity after acute, low dose ultraviolet B radiation in UVB-resistant mice. Recent evidence indicates that conventional doses of hapten as well as acute, low dose ultraviolet B radiation destroy virtually all epidermal Langerhans cells, which leads to the conclusions that (a) dermal antigen presenting cells have a prominent role to play in contact hypersensitivity induction, and that (b) Langerhans cell provide this function only in normal skin, and only if non-toxic amounts of hapten are present. We have now explored the ability of suprathreshold, threshold, and sub-threshold doses of hapten to induce tolerance when painted on or injected into normal skin or skin exposed to ultraviolet B radiation. Our results indicate that a single exposure of low dose, ultraviolet B radiation generated tolerance-promoting signals within the epidermis when a threshold dose of hapten was painted on the exposed site. By contrast, suprathreshold doses of hapten painted on skin after four consecutive daily doses of ultraviolet B radiation led to tolerance that arose exclusively from cells within the dermis. In absence of ultraviolet B radiation, epicutaneously applied hapten failed uniformly to induce tolerance, whether applied at suprathreshold, threshold or sub-threshold doses. We conclude that normal skin lacks cells with inherent tolerance-promoting capacity, but that cells of this type can emerge within either epidermis or dermis after exposure to acute, low dose ultraviolet B radiation.

Functional lip reconstruction with a radial forearm free flap combined with a masseter muscle transfer after wide total excision of the chin

Total lower lip reconstruction was accomplished by combining a radial forearm free flap with a masseter muscle transfer. The patient, who had T4 carcinoma, had the entire lower lip resected including the depressor anguli oris muscle. A radial forearm flap was used to reconstruct the lower lip lining and the floor of the oral cavity. The right and left masseter musculofascial flaps were elevated and transferred in the medial-superior direction, and the peripheral margins of the flaps were sutured together. The lateral margins of the flaps were then sutured to the orbicularis oris muscle of the upper lip. Good sphincter function was obtained more than 1 year after the operation, electromyography revealed almost normal mobility of the transferred masseter muscles, and no sagging of the masseter muscle sling was observed. This procedure appears to be effective for the reconstruction of sphincter function of the lower lip after wide excision of the entire chin.

Smooth muscle layer-dependent distribution of 5-hydroxytryptamine(7) receptor in the porcine myometrium

1. To analyse the mechanisms of muscle layer-dependent inhibition of porcine myometrial contractility by 5-hydroxytryptamine (5-HT), the effects of 5-HT, 5-carboxamidotryptamine(5-CT), 5-methoxytryptamine (5-MeOT), forskolin and cyclic adenosine 3', 5'-monophosphate (cyclic AMP) analogues on spontaneous and stimulant-induced contractions were examined in longitudinal (LM) and circular muscles (CM). In addition, accumulation of cyclic AMP by 5-HT and distribution of 5-HT(7) receptors in LM and CM layers were compared using biochemical and molecular approaches. 2. 5-HT receptor agonists inhibited the spontaneous contractions of LM and CM (5-CT>5-HT>5-MeOT), but CM was more sensitive than was LM. The inhibition by the agonists was antagonized by methiothepin (100 nM). 3. Carbachol-, high-K(+)-, histamine- and Ca(2+)-induced contractions were inhibited by 5-HT with different responses (CM>LM). Even in the presence of 3-isobutyl-1-methylxanthine (IBMX), the inhibition by 5-HT in the CM was still more conspicuous than that in the LM. 4. Compared with the CM, the inhibition of spontaneous contraction by forskolin, dibutyryl-cyclic AMP and 8-bromo-cyclic AMP was marked in the LM. 5. 5-HT (1 nM - 1 microM) increased the cyclic AMP in both muscle layers, but the increment in the CM was higher than that in the LM whether IBMX was present or not. 6. LM and CM layers contained a single class of [(3)H]-5-CT binding sites with a similar K(d) value (0.21 - 0.24 nM). However, B(max) (5-HT(7) receptor concentration) in the CM (120.6 fmol mg(-1) protein) was higher than that in the LM (30.4 fmol mg(-1) protein). 7. The molecular study (reverse transcription polymerase chain reaction) demonstrated the expression of 5-HT(7) receptor mRNA in the CM was higher than that in the LM. 8. These results suggest that the muscle layer-dependent difference in inhibition by 5-HT is not restricted to spontaneous contraction but applies to various contractions in the porcine myometrium. Different inhibition of the contractility by 5-HT is caused by muscle layer-related accumulation of cyclic AMP (CM>LM), due to smooth muscle-layer dependent distribution (CM>LM) of 5-HT(7) receptors.

Agonists trigger G protein-mediated activation of the CPI-17 inhibitor phosphoprotein of myosin light chain phosphatase to enhance vascular smooth muscle contractility

Myosin light chain phosphatase (MLCP) plays a pivotal role in smooth muscle contraction by regulating Ca(2+) sensitivity of myosin light chain phosphorylation. A smooth muscle phosphoprotein called CPI-17 specifically and potently inhibits MLCP in vitro and in situ and is activated when phosphorylated at Thr-38, which increases its inhibitory potency 1000-fold. We produced a phosphospecific antibody for this site in CPI-17 and used it to study in situ phosphorylation of endogenous CPI-17 in arterial smooth muscle in response to agonist stimulation. In the intact femoral artery, CPI-17 phosphorylation was negligible at the resting state and was not increased during contraction induced by K(+) depolarization. The Ca(2+)-sensitizing agonists histamine and phenylephrine induced nearly equivalent contractions, but histamine generated significantly higher levels of CPI-17 phosphorylation. In alpha-toxin-permeabilized strips at pCa 6.7, contractile force and CPI-17 phosphorylation were proportional in response to histamine, guanosine 5'-O-(gamma-thiotriphosphate), and histamine plus guanyl-5'-yl thiophosphate, implying that histamine increased CPI-17 phosphorylation through activation of G proteins. Inhibitors of Rho-kinase (Y27632) and protein kinase C (PKC; GF109203X) reduced contraction and CPI-17 phosphorylation in parallel, suggesting that CPI-17 functions downstream of Rho kinases and PKC. The results show that agonists such as histamine signal through phosphorylation of CPI-17 to produce Ca(2+) sensitization of smooth muscle contraction.

Characterization of functional endothelin receptors in the porcine myometrium

To characterize the endothelin (ET) receptor that mediates the contraction induced by ET-1 in the porcine myometrium, we carried out a contraction study, radioligand binding study and molecular study (reverse transcription polymerase chain reaction) for detection of ET receptor-coding genes (mRNA). ET-1 (1 nM-1 microM) caused a tetrodotoxin-insensitive contraction in both longitudinal and circular muscles, but the longitudinal muscle was more sensitive to ET-1 than was the circular muscle. On the other hand, ET-3 and sarafotoxin S6c were less effective to cause a contractile response. The contraction induced by ET-1 was markedly inhibited by BQ123 and FR139317, but BQ788 only slightly inhibited the response induced by ET-1. The radioligand binding study indicated the presence of a single class of 125I-ET-1 binding sites with the same Kd value in both muscle layers. However, Bmax in the longitudinal muscle (3252 fmol/mg protein) was significantly higher than that in the circular muscle (1883 fmol/mg protein). ET-1 and FR139317 inhibited the specific 125I-ET-1 binding completely, but ET-3, sarafotoxin S6c and BQ3020 only slightly inhibited the specific binding (inhibition, 10-20%), suggesting that ET(A) is the dominant ET receptor subtype in the porcine myometrium. The results of the molecular study indicated the expression of both ET(A) and ET(B) receptor-coding genes in the porcine myometrium. In conclusion, ET-1 causes contraction of the porcine myometrium through activation of the ET(A) receptor present on smooth muscle cells. There is a marked muscle layer-related difference (longitudinal muscle > circular muscle) in the ET-1-induced contraction and the ET(A) receptor concentration.