Thermally oxidized dietary fat and colon carcinogenesis in rodents

Thermally oxidized animal fat (beef tallow) was assessed for colon cancer-promoting and -initiating activity in F-344 rats and CF-1 mice with the use of the aberrant crypt focus (ACF) assay. In two promotion studies, extensively oxidized beef tallow (110 degrees C for 144-168 h, peroxide value approx 200 meq/kg, with > 80% loss of allylic and olefinic protons) had relatively little effect on the growth of ACF in F-344 rats. The multiplication constant for treatment/control of ACF size in aberrant crypts per ACF at 100 days was 1.07 (95% confidence interval = 1.01-1.14) and 0.98 (95% confidence interval = 0.91-1.06). ACF size was not affected by less extensively oxidized beef tallow or by a 10-fold reduction of dietary alpha-tocopherol during the growth of the ACF. In initiation studies, extensively oxidized beef tallow administered by gavage increased the number of animals with ACF and the number of ACF per colon (11 of 23 and 5 of 29 animals with ACF; 1.09 +/- 0.29 and 0.21 +/- 0.09 ACF/colon, respectively). Less severely oxidized beef tallow was without effect. Further studies with CF-1 mice confirmed that extensively oxidized beef tallow increased numbers of animals with ACF and average ACF per colon. The unsaturated aldehyde acrolein was without effect in the ACF assay. These data suggest that highly thermolyzed beef tallow contains an uncharacterized initiator or leads to conditions in which spontaneously initiated ACF are increased.

Changes in collagen phenotypes during progression and regression of cardiac hypertrophy

OBJECTIVE

Excessive deposition of collagen has been implied to be responsible for abnormal stiffness and altered cardiac function during hypertrophy and heart failure. In the present paper we studied the changes in collagen and their phenotypes during development of cardiac hypertrophy in spontaneously hypertensive rats (SHR) compared to age- and sex-matched Wistar Kyoto (WKY). We also studied the changes in collagen after regression of hypertrophy, with antihypertensive therapy with ACE inhibitors, captopril (C) and lisinopril (L).

METHOD

Collagen was extracted from the heart tissue by cyanogen bromide (CNBr) digestion. Collagen phenotypes were separated and quantified by SDS-polyacrylamide gel electrophoresis. The transcript levels(mRNA) of collagen phenotypes were determined by Northern analysis.

RESULTS

Our studies showed that the ventricular collagen and their phenotypes did not alter in SHR during the first 6 months of progression of hypertrophy when compared to WKY. After 40 weeks, however, in SHR there was an unexpected rise in collagen content and the distribution of collagen phenotype differs compared to WKY, especially during the chronic phase of hypertrophy (65 weeks of age). In WKY during the aging process there was a gradual increase in type III collagen, whereas in SHR it plateaus after 40 weeks of age. Treatment with antihypertensive drugs captopril and lisinopril showed a similar degree of reduction in blood pressure (P < 0.001), regressed hypertrophy (P < 0.001), and reduced collagen, whereas decrease in type I to III ratio was found with captopril only, but not with lisinopril. This decrease in type I to III ratio due to captopril treatment is primarily due to an increase in type III collagen (both protein and transcript level) in SHR.

CONCLUSION

Our data showed, for the first time, that during the chronic phase of hypertrophy in SHR there is a gradual reduction in type I to III ratio, primarily due to a lack of increase in type III collagen during chronic phase of hypertrophy. This suggests that quality of collagen is an important factor in determining the degree of cardiac stiffness. Our data also showed that not all ACE inhibitors have similar actions on collagen phenotype production. This suggests that perhaps the mechanism of action of ACE inhibitors on collagen are independent of its effect on angiotensin II formation.

Inhibition of RPE cell-mediated matrix adhesion and collagen gel contraction by crovidisin, a collagen-binding snake venom protein

PURPOSE

Cell-mediated collagen gel contraction plays an important role in the pathogenesis of proliferative vitreoretinopathy (PVR). Anti-adhesion therapy has been suggested as a promising strategy in the treatment of PVR. Crovidisin, a snake venom protein isolated from Crotalus viridis, has been shown to bind selectively to collagen and to inhibit collagen-induced platelet aggregation. In the present study, the effectiveness of crovidisin in inhibiting the attachment of retinal pigment epithelial (RPE) cells to collagen, and RPE cell-mediated collagen gel contraction, was evaluated.

METHODS

Fluorescein isothiocyanate (FITC)-conjugated crovidisin was prepared and used to evaluate its binding affinity for collagen type I, fibronectin, vitronectin, and laminin. The inhibitory effect of crovidisin on RPE cell-mediated extracellular matrix attachment and collagen gel contraction was evaluated by cell adhesion and type I collagen gel contraction assays. The cytotoxic effect of crovidisin was examined with a cell proliferation assay, using the Alamar blue method. Flavoridin, an Arg-Gly-Asp-containing peptide from viper venom, was used for comparison.

RESULTS

FITC-conjugated crovidisin bound selectively to collagen type I with high affinity. It did not bind to other matrix proteins, including fibronectin, vitronectin and laminin, nor to RPE cells. Crovidisin inhibited RPE cell attachment to type I collagen in a dose-dependent manner. This inhibitory effect was enhanced by the presence of flavoridin. Crovidisin also dose-dependently inhibited RPE cell-mediated type I collagen gel contraction. Crovidisin was non-toxic to RPE cells.

CONCLUSIONS

Crovidisin, a snake venom-derived collagen-binding protein, possessing an inhibitory activity on RPE cell-collagen interaction and RPE cell-mediated collagen gel contraction, may be a useful tool for studying cell-collagen interaction, and a potential anti-adhesion therapeutic agent for ocular disorders in which cell-collagen interaction in involved, such as PVR.

Comparison of cryotherapy and laser photocoagulation in stage III retinopathy of prematurity

Both cryotherapy and laser photocoagulation have been advocated for the treatment of stage III retinopathy of prematurity (ROP). In this retrospective study, we looked at which treatment was more effective and caused fewer complications. The outcomes of 23 patients (45 eyes) with stage III ROP treated with transconjunctival cryotherapy or indirect diode laser photocoagulation were reviewed. Group 1 (10 patients, 20 eyes) received cryotherapy and group 2 (13 patients, 25 eyes) received photocoagulation. In group 1, all had progressive ROP and one patient had bilateral neovascularization involving zone I. After treatment, 17 eyes had regression of ROP with good anatomic results, one eye had regression of the disease with mild to moderate macular ectopia and vessel traction, and two eyes (one patient) with zone I involvement advanced to stage V in 2 weeks. In group 2, 12 patients had threshold ROP, two had neovascularization involving zone I, and one patient had prethreshold zone I ROP. After treatment, 24 eyes had regression of ROP with good anatomic results and one eye had mild ectopic macula. Two eyes received two sessions of treatment. The results suggest that photocoagulation is at least as effective as cryotherapy and may be a favorable alternative for zone I ROP.

Purinoceptor-stimulated phosphoinositide hydrolysis in Madin-Darby canine kidney (MDCK) cells

Extracellular nucleotides, acting through P2-purinoceptors, have been implicated in the regulation of ion transport in epithelia, including Madin-Darby canine kidney (MDCK) cells. In this study, experiments were conducted to characterize the P2-purinoceptor subtype on MDCK cells responsible for stimulating inositol phosphate (IP) accumulation using a range of nucleotide analogues. In Ca2+- and Mg2+-free Krebs-Henseleit solution (KHS), ATP, UTP, and ATPgammaS caused an increase in IP accumulation as a function of concentration with comparable kinetics. The order of potency for the nucleotide analogues was UTP = ATPgammaS > ATP = 2-chloro ATP (Cl-ATP) >> alpha,beta-methylene ATP (alpha,beta-MeATP) = 2-methylthio ATP (2MeSATP). Selective agonists for P1-, P2X- and P2Y-purinoceptors, such as N6-cyclopentyl adenosine, AMP, alpha,beta-MeATP, and 2MeSATP, had little effect. Stimulation of MDCK cells with maximally effective concentrations of ATP and UTP showed no additive effect and furthermore, ATP, UTP, and ATPgammaS induced cross-desensitization of the IP response, suggesting that ATP and UTP act upon a common nucleotide receptor, i.e. a P2U-purinoceptor. In Ca2+- and Mg2+-containing KHS, the concentration-response curves of ATP, UTP, and ATPgammaS were shifted to the right of those obtained in Ca2+- and Mg2+-free buffer, and asymptotic maxima were not reached, indicating that ATP4- and not MgATP2- or CaATP2- was the active agonist. Pretreatment of MDCK cells with pertussis toxin (PTX) inhibited ATP- and UTP-induced IP accumulation in a concentration-dependent fashion but did not completely abolish the IP accumulation, indicating that a PTX-sensitive G protein was partially involved in the IP response. In conclusion, ATP- and UTP-stimulated IP accumulation in MDCK cells appears to be mediated through the activation of P2U-purinoceptors coupled to a G protein that is partially sensitive to PTX. A form of nucleotide uncomplexed with divalent ions such as ATP4- seems to be the preferential agonist form for the purinoceptors on MDCK cells.

Inhibition of 5-hydroxytryptamine-induced phosphoinositide hydrolysis and Ca2+ mobilization in canine cultured tracheal smooth muscle cells by phorbol ester

1. Regulation of the increase in inositol-1,4,5-trisphosphate (IP3) production and intracellular Ca2+ concentration ([Ca2+]i by protein kinase C (PKC) was investigated in canine cultured tracheal smooth muscle cells (TSMCs). Stimulation of TSMCs by 5-hydroxytryptamine (5-HT) caused an initial transient [Ca2+]i peak followed by a sustained elevation of [Ca2+]i in a concentration-dependent manner. 2. Pretreatment of TSMCs with phorbol 12-myristate 13-acetate (PMA, 1 microM) for 30 min blocked the 5-HT-induced IP3 formation and Ca2+ mobilization. This inhibition was reduced after the cells had been incubated with PMA for 8 h, and within 48 h the 5-HT-induced Ca2+ mobilization reached the same extent as control cells. 3. The concentration of PMA that gave half-maximal inhibition of 5-HT-induced increase in [Ca2+]i was 4 nM. Pretreatment of TSMCs with staurosporine (1 microM) of GF109203X (0.1 microM), PKC inhibitors, inhibited the ability of PMA to attenuate 5-HT-induced responses, suggesting that the inhibitory effect of PMA was mediated through the activation of PKC. 4. In parallel with the effect of PMA on 5-HT-induced IP3 formation and Ca2+ mobilization, the translocation and down-regulation of PKC isozymes were determined by Western blot analysis in TSMCs. Analysis of cell extracts by Western blotting with antibodies against different PKC isozymes revealed that TSMCs expressed PKC-alpha, beta I, beta II, delta, epsilon, theta and zeta. With PMA treatment of the cells for various times, translocation of PKC-alpha, beta I, beta II, delta, epsilon, and theta from the cytosol to the membrane was seen after 5 min, 30 min, 2 h, and 4 h treatment. However, 24 h treatment caused a partial down-regulation of these PKC isozymes PKC-zeta was not significantly translocated and down-regulated at any of the times tested. 5. In conclusion, these results suggest that activation of PKC may inhibit the receptor-mediated phosphoinositide hydrolysis and consequently attenuate the [Ca2+]i increase or inhibit both responses independently. The translocation of PKC-alpha, beta I, beta II, delta, epsilon, and theta induced by PMA caused an attenuation of 5-HT-stimulated IP3 accumulation and Ca2+ mobilization in TSMCs.

Pars plana vitrectomy in the treatment of combined rhegmatogenous retinal detachment and choroidal detachment in aphakic or pseudophakic patients

BACKGROUND AND OBJECTIVE

The presence of extensive choroidal detachment (CD) in eyes with rhegmatogenous retinal detachment (RRD) is a major preoperative complication. Conventional treatment consists of 7 days to a few weeks of systemic and topical steroids followed by scleral buckling and drainage of suprachoroidal fluid. The author studied the usefulness of pars plana vitrectomy in the management of RRD combined with CD.

PATIENTS AND METHODS

Ten consecutive patients with RRD complicated by CD were treated with pars plana vitrectomy. Nine had had previous cataract extraction, and one patient had pars plana lensectomy at the time of the surgery. The severity of the CD was evaluated with preoperative ophthalmologic echography. Sclerotomy sites for infusion cannulas were chosen in the area with less CD. Six-millimeter infusion cannulas were used. Pars plana vitrectomy, membrane peeling, and internal fluid-gas exchange with encircling scleral buckle placement were performed in a standard fashion. One patient had silicone oil injected.

RESULTS

In each case, suprachoroidal fluid drained spontaneously through the sclerotomy sites around the vitrectomy instruments during the initial course of the operation without extra sclerotomy. Immediate intraoperative retinal reattachment was achieved in 10 cases. The retina remained attached in 9 cases during at least 6 months of follow-up without additional surgery.

CONCLUSION

These cases demonstrate the usefulness of pars plana vitrectomy in treating RRD with CD in aphakic or pseudophakic eyes. This method may be an favorable alternative to conventional treatment.

Effect of forskolin on bradykinin-induced calcium mobilization in cultured canine tracheal smooth muscle cells

The effects of increases in intracellular adenosine 3':5'-cyclic monophosphate (cyclic AMP) on bradykinin (BK)-induced generation of inositol phosphates (IPs) and Ca2+ mobilization were investigated in canine cultured tracheal smooth muscle cells (TSMCs). Pretreatment of TSMCs with either forskolin or dibutyryl cyclic AMP attenuated BK-stimulated responses. The inhibitory effects of these agents produced both a depression of the maximal response and a shift to the right of the concentration-response curves of BK. The water-soluble forskolin analogue L-858051, 7-deacetyl-7 beta-(r-N-methylpiperazino)-butyryl forskolin, significantly attenuated BK-stimulated IPs accumulation, while 1,9-dideoxy forskolin, an inactive forskolin, had little effect on IPs response. Moreover, SQ-22536, 9-(tetrahydro-2-furanyl)-9-H-purin-6-amine, an inhibitor of adenylate cyclase, and both H-89, N-(2-aminoethyl)-5-isoquinolinesulfonamide, and HA-1004, N-(2-guanidinoethyl)-5-isoquinolinesulfonamide, inhibitors of cyclic AMP-dependent protein kinase (PKA), reversed the ability of forskolin to attenuate BK-stimulated IPs accumulation. The KD and Bmax, values of the BK receptor for [3H]BK binding were not significantly changed by forskolin treatment for 30 min and 4 h. The AlF4(-)-induced IPs accumulation was attenuated by forskolin, indicating that G protein(s) are directly activated by AlF4- and uncoupled to phospholipase C by forskolin treatment. These results suggest that activation of cyclic AMP/PKA might inhibit the BK-stimulated PI breakdown and consequently reduce the [Ca2+]i increases or inhibit independently both responses, which is distal to the BK receptor in canine cultured TSMCs.

Mechanism of extracellular ATP-induced proliferation of vascular smooth muscle cells

The mitogenic effect of extracellular ATP was examined in cultured rat aortic smooth muscle cells (VSMCs). ATP, 2-methylthio-ATP, and ADP stimulated [3H]thymidine and [3H]leucine incorporation and cell growth. AMP, adenosine, UTP, and P2x agonists showed little of these effects. Reactive blue 2, a P2Y purinoceptor antagonist, was effective in suppressing the mitogenic effect of ATP and 2-methylthio-ATP, indicating that extracellular ATP-induced VSMC proliferation is mediated by P2Y purinoceptors. The P2Y purinoceptor activation was coupled to a pertussis toxin (PTX)-insensitive G protein (Gq) and triggered phosphoinositide hydrolysis with subsequent activation of protein kinase C (PKC), Raf-1, and mitogen-activated protein kinase (MAPK) in VSMCs. In response to ATP, both 42-and 44-kDa MAPKs were activated, and tyrosine was phosphorylated. Western blot analysis using PKC isozyme-specific antibodies indicated that VSMCs express PKC-alpha, PKC-delta, and PKC-zeta. A complete down-regulation of PKC-alpha and PKC-delta was seen after 24-hr treatment with 12-O-tetradecanoylphorbol-13-acetate. When cells were pretreated with 12-O-tetradecanoyl-phorbol-13-acetate for 24 hr and subsequently challenged with ATP, Raf-1 activation and 42-kDa as well as 44-kDa MAPK tyrosine phosphorylation failed to be induced. These results demonstrate that ATP-induced Raf-1 and MAPK activations involve the activation of PKC-alpha and PKC-delta. P2Y purinoceptor stimulation with ATP also caused accumulation of c-fos and c-myc mRNAs. Both Reactive blue 2 and staurosporine significantly blocked this increase by ATP. In conclusion, the mitogenic effect of ATP seemed to be triggered by activation of the Gq protein-coupled P2Y purinoceptor that led to the formation of inositol trisphosphate and activation of PKC. PKC and, in turn, Raf-1 and MAPK were then activated, leading eventually to DNA synthesis and cell proliferation.

Pharmacological and functional characterization of bradykinin receptors in canine cultured tracheal epithelial cells

1. A direct [3H]-bradykinin ([3H]-BK) binding assay has been used to characterize the BK receptors in canine cultured tracheal epithelial cells (TECs). Based on receptor binding assay, TECs have specific, saturable, high-affinity binding sites for [3H]-BK. 2. The specific [3H]-BK binding was time- and temperature-dependent. Equilibrium of association of [3H]-BK with the BK receptors was attained within 30 min at room temperature and 1 h at 4 degrees C, respectively. 3. Analysis of binding isotherms yielded an apparent equilibrium dissociation constant (KD) of 1.5 +/- 0.2 nM and a maximum receptor density (Bmax) of 53.2 +/- 5.2 fmol mg-1 protein. The Hill coefficient for [3H]-BK binding was 1.00 +/- 0.02. The association (K1) and dissociation (K-1) rate constants were (7.6 +/- 1.1) x 10(6) M-1 min-1 and (9.2 +/- 1.5) x 10 M-3 min-1, respectively. KD, calculated from the ratio of K-1 and K1, was 1.2 +/- 0.3 nM, a value close to that calculated from Scatchard plots of binding isotherms. 4. Neither a B1 receptor selective agonist (des-Arg9-BK, 0.1 nM - 10 microM) nor antagonist ([Leu8, des-Arg9]-BK, 0.1 nM - 10 microM) significantly inhibited [3H]-BK binding to TECs, which excludes the presence of B1 receptors in canine TECs. 5. The specific binding of [3H]-BK to canine TECs was inhibited by the B2 receptor selective antagonists ([D-Arg0, Hyp3, Thi5, D-Tic7, Oic8]-BK (Hoe 140, 0.1 nM-10 microM) and [D-Arg0, Hyp3, Thi5.8, D-Phe7]-BK, 0.1 nM - 10 microM) and agonists (BK and kallidin, 0.1 nM-10 microM) with a best fit by a one-binding site model. The order of potency for the inhibition of [3H]-BK binding was kallidin = BK = Hoe 140 > [D-Arg0, Hyp3, Thi5,8, D-Phe7]-BK. 6. BK and kallidin significantly induced concentration-dependent accumulation of IPs with a half-maximal response (EC50) at 17.6 +/- 3.5 and 26.6 +/- 5.3 nM, respectively, while the B1-selective agonist, des-Arg9-BK did not stimulate IPs accumulation and the B1-selective antagonist [Leu8, des-Arg9]-BK did not inhibit BK-induced IPs accumulation. Two B2-selective antagonists, Hoe 140 and [D-Arg0, Hyp3, Thi5,8, D-Phe7]-BK, inhibited BK-stimulated IPs accumulation with apparent pKB values of 8.8 +/- 0.3 and 7.0 +/- 0.3, respectively. 7. It is concluded that the pharmacological characteristics of the BK receptors in canine cultured TECs are primarily of the B2 receptor subtype which might regulate the function of tracheal epithelium through the activation of this receptor subtype coupling to PI hydrolysis.

Pharmacological characteristics of BDTI, a new isoquinoline-derived beta 2-adrenoceptor agonist, in canine trachea and rat heart

The tracheal relaxing effects and beta 2-selectivity of BDTI (1-benzyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline HBr) were investigated in canine trachea and rat heart by radioligand binding assay and pharmacological experiments in comparison with those of other beta-adrenoceptor agonists, salbutamol and isoprenaline. The potency of relaxing effect on carbachol-induced contraction in isolated canine trachea was in the order of isoprenaline (pD2 = 6.70 +/- 0.08) > BDTI (6.11 +/- 0.06) approximately salbutamol (6.14 +/- 0.08). ICI-118,551 (a selective beta 2-antagonist) and atenolol (a selective beta 1-antagonist) inhibited the relaxant action of BDTI with pKB values of 8.4 and 5.3, respectively, corresponding to high affinity for ICI-118,551 and low affinity for atenolol in antagonizing this response. The Kd values of radioligand ([3H]-CGP12177) were 453.3 +/- 30.8 and 563.4 +/- 96.7 pmol/l in cultured canine tracheal smooth muscle cells (TSMCs) and rat cardiomyocytes, respectively, and the Bmax values were 64.6 +/- 10.7 and 245.7 +/- 44.5 fmol/mg protein, respectively. BDTI, salbutamol and isoprenaline inhibited the binding of [3H]-CGP12177 in a concentration-dependent manner in cultured canine TSMCs (Ki 0.73 +/- 0.15, 0.75 +/- 0.21 and 0.24 +/- 0.05 mumol/l, respectively) and rat cardiomyocytes (Ki 2.76 +/- 0.36, 2.31 +/- 0.26 and 0.22 +/- 0.03 mumol/l, respectively). These results demonstrated that BDTI possessed moderate selectivity (3.8-fold) to beta 2-adrenoceptors as judged from the Ki (heart)/Ki (trachea) value (salbutamol 3.1-fold, isoprenaline 0.92-fold). BDTI and salbutamol also stimulated cAMP formation in a concentration-dependent manner in cultured canine TSMCs (EC50 0.5 +/- 0.2 and 0.4 +/- 0.1 mumol/l, respectively) and rat cardiomyocytes (EC50 6.2 +/- 0.5 and 5.7 +/- 0.6 mumol/l, respectively). The selectivity of BDTI and salbutamol for beta 2-adrenoceptors on the cAMP response were 12.4 and 14.3 times, respectively. It is concluded that BDTI is a beta 2-selective adrenoceptor agonist.

Effect of cAMP elevating agents on carbachol-induced phosphoinositide hydrolysis and calcium mobilization in cultured canine tracheal smooth muscle cells

The effects of increases in intracellular adenosine 3',5'-cyclic monophosphate (cAMP) on carbachol-induced generation of inositol phosphates (IPs) and increases in intracellular Ca2+ ([Ca2+]i) were investigated in canine cultured tracheal smooth muscle cells (TSMCs). The cAMP elevating agents, cholera toxin (CTX) and forskolin, induced concentration- and time-dependent cAMP formation with half-maximal effects (-logEC50) at concentrations of 7.6 +/- 1.3 g/ml and 4.8 +/- 0.9 M, respectively. Forskolin caused a concentration-dependent inhibition of carbachol-induced increase in [Ca2+]i with half-maximal inhibition (-logEC50) at 5.2 +/- 0.7 M. Pretreatment of TSMCs with either CTX (10 micrograms/ml, 4 h), forskolin (10-100 microM, 30 min), or dibutyryl cAMP (1 mM, 30 min) inhibited carbachol-stimulated Ca2+ mobilization and IPs accumulation. The inhibitory effects of these agents produced both depression of the maximal response and a shift to the right of the concentration-response curve of carbachol without changing the EC50 values. After treatment with forskolin for 24 h, carbachol-induced IPs accumulation and Ca2+ mobilization were close to those of control group. SQ-22536 [9-(tetrahydro-2-furanyl)-9H-purin-6-amine, 10 microM], an inhibitor of adenylate cyclase, and HA-1004 [N-(2-guanidinoethyl)-5-isoquinolinesulfonamide hydrochloride, 50 microM], an inhibitor of cAMP-dependent protein kinase (PKA), attenuated the ability of forskolin to inhibit carbachol-induced IPs accumulation. Moreover, the inactive analogue of forskolin, 1,9-dideoxy forskolin, did not inhibit these responses evoked by carbachol, suggesting that activation of cAMP/PKA was involved in these inhibitory effects of forskolin. The KD and Bmax values of the muscarinic receptor (mAChR) for [3H]-N-methyl scopolamine binding were not significantly changed by forskolin treatment for 30 min and 24 h, suggesting that the inhibitory effect of forskolin is distal to the mAChR. The locus of this inhibition was further investigated by examining the effect of forskolin treatment on AIF4(-)-stimulated IPs accumulation in canine TSMCs. The AIF4(-)-induced response was inhibited by forskolin, supporting the notion that G protein(s) are directly activated by AIF4- and uncoupled to phospholipase C by forskolin treatment. We conclude that cAMP elevating agents inhibit carbachol-stimulated generation of IPs and Ca2+ mobilization in canine cultured TSMCs. Since generation of IPs and increases in [Ca2+]i are very early events in the activation of mAChRs, attenuation of these events by cAMP elevating agents might well contribute to the inhibitory effect of cAMP on tracheal smooth muscle formation.

Differential induction and regulation of c-jun, junB, junD and c-fos by human papillomavirus type 11 E5a oncoprotein

The E5a gene of human papillomavirus type 11 (HPV-11) is a transforming oncogene. In this study, we investigated the mechanism of E5a induced transformation. Our results show that the expression of c-jun and junB, but not junD, was activated by HPV-11 E5a in NIH 3T3 cells and human epidermal keratinocytes. However, the expression of c-fos was activated by E5a in NIH 3T3 cells, but not in keratinocytes. We further investigated the mechanism of c-jun and junB induction by E5a. The amount of c-jun and junB RNAs correlated with the amount of E5a RNA in the heavy metal inducible system. E5a constitutively activated the expression of c-jun and junB at the initiation of transcription level. In addition, analyses of the effect of serum on c-jun expression in E5a transformed human epidermal keratinocytes show that EGF might have a stimulatory effect on c-jun gene expression in E5a expressing keratinocytes.

Inhibitory effect of phorbol ester on bradykinin-induced phosphoinositide hydrolysis and calcium mobilization in cultured canine tracheal smooth muscle cells

Regulation of the increase in inositol 1,4,5-trisphosphate (IP3) production and intracellular Ca2+ concentration ([Ca2+]i) by protein kinase C (PKC) was investigated in cultured canine tracheal smooth muscle cells (TSMCs). Stimulation of TSMCs by bradykinin (BK) led to IP3 formation and caused an initial transient peak followed by a sustained elevation of [Ca2+]i in a concentration-dependent manner. Pretreatment of TSMCs with phorbol 12-myristate 13-acetate (PMA, 1 microM) for 30 min blocked the BK-induced IP3 formation and Ca2+ mobilization. However, this inhibition was reduced after incubating the cells for 4 h with PMA. Inactive phorbol ester, 4 alpha-phorbol 12,13-didecanoate at 1 microM, did not inhibit these responses to BK. Prior treatment with staurosporine (1 microM), a PKC inhibitor, inhibited the effect of PMA on the BK-induced response, suggesting that the effect of PMA is mediated by the activation of PKC. In parallel experiments, a change of PKC activity was observed. PMA rapidly decreased PKC activity in the cytosol of TSMCs, while increasing it transiently in the cell membranes within 30 min. Thereafter the membrane-associated PKC activity decreased and persisted for at least 24 h of PMA treatment. Moreover, treatment with 1 microM PMA for 2 and 24 h did not significantly change the KD and Bmax of the BK receptor for [H]BK binding (control: KD = 2.3 +/- 0.3 nM, Bmax = 25.2 +/- 1.4 fmol/mg protein). These results suggest that activation of PKC inhibit IP3 accumulation and consequently attenuate [Ca2+]i increase or inhibit independently both responses. The PMA-induced inhibition of responses to BK was associated with an increase in membranous PKC activity.

HLA-A, B antigens and their linkage with HLA-DR among blood donors in Taiwan

The distribution pattern of HLA antigens varies to a great extent among different ethnic groups. Availability of HLA antigen distribution information is very important for disease association study, paternity testing and recipient/donor matching. Analysis of 11,383 blood donors from the Taipei Blood Center, Chinese Blood Services Foundation (CBSF), gave evidence that the distribution pattern of HLA-A,B antigens was unique, yet closer to Southern Chinese with higher A11, A33, B16, B40 frequencies, and B46, B48, B54 as unique antigens when compared with Caucasians. Pairwise linkage disequilibrium analysis between HLA-A, -B and -DR antigens from 238 blood donors revealed unique linkages of A33-B17, A2-B46, A11-B15, A24-B40; A11-DR5, A2-DR9, B17-DR3, B40-DR8, B13-DR2. In addition, A33-B58-DR3 were the most frequent 3-loci haplotypes. Knowing linkage disequilibrium between HLA loci and preferential association of DR specificity among various HLA-A,B haplotypes may provide a more efficient strategy to obtain an HLA-DR or HLA-D region compatible unrelated bone marrow donor from an existing HLA data bank.

Evaluation of screening kits for the detection of anti-human immunodeficiency virus type 1 and 2 (HIV-1/2) antibodies

HIV-1/HIV-2 3rd generation (Abbott), Wellcozyme HIV 1 + 2 (Murex), Enzygnost Anti-HIV 1/-HIV 2 (Behring), and Genelavia Mixt (Sanofi Diagnostics Pasteur) are currently registered by authorities as enzyme immunoassays (EIAs) for detecting HIV-1/2 infection. The present study dissects these reagents by means of the major antigenic components, assay principles and their actual performance. The performances have been evaluated by their test results in international panels of seroconversion, mixed titer performance and HIV-1/2 combination, respectively. Those EIA tests were further used to examine 26 potentially false-reacting samples, serial diluted sera prepared from two confirmed positive specimens and 720 specimens obtained from random blood donors in the Taipei Blood Center, Chinese Blood Services Foundation (CBSF). The results showed that, although standard sera of the mixed titer, performance and HIV-1/2 combination rows could not distinguish significantly among various EIAs, the seroconverting samples clearly showed their differences. The differences, as calculated by using 3 of 4 seroconverting sera, was a backward window period ranging from 19 to 23 days as compared to the detection of HIV-1 antigens. Together, these studies strongly suggest that assays which are capable of detecting HIV-specific IgM and IgG antibodies have a shorter seroconversion window. Furthermore, the HIV-2 antigen seems to be crucial for successful detection of anti-HIV-2. Finally, testing anti-HIV-1/2 in the routine screenings is expected not to increase the exclusion rate of blood units currently acquired from the examination of anti-HIV-1. Consequently, with both HIV-1/2 specificities and the ability of early detection, IgM/IgG-captured EIAs may represent a better screening method than assays based solely on the detection of HIV-specific IgG.

Effect of phorbol ester on phosphoinositide hydrolysis and calcium mobilization induced by endothelin-1 in cultured canine tracheal smooth muscle cells

Regulation of the increase in inositol 1,4,5-trisphosphate (IP3) production and intracellular Ca2+ concentration ([Ca2+]i) by protein kinase C (PKC) was investigated in cultured canine tracheal smooth muscle cells (TSMCs). Stimulation of TSMCs by endothelin-1 (ET-1) led to IP3 formation and caused an initial transient peak followed by a sustained elevation of [Ca2+]i in a concentration-dependent manner. Pretreatment of TSMCs with phorbol 12-myristate 13-acetate (PMA, 1 microM) for 30 min blocked the ET-1-induced IP3 formation and Ca2+ mobilization. However, this inhibition was reduced after incubating the cells for 8 h with PMA. Following preincubation, ET-1-induced Ca2+ mobilization recovered with time and reached the same extent of control cells within 48 h. The concentrations of PMA that gave half-maximal inhibition (-logEC50) of ET-1-induced IP3 formation and increase in [Ca2+]i were 8.6 and 8.4 M, respectively. Prior treatment of TSMCs with staurosporine (1 microM), a PKC inhibitor, inhibited the ability of PMA to attenuate ET-1-induced responses, suggesting that the inhibitory effect of PMA is mediated through the activation of PKC. In parallel with the effect of PMA on the ET-1-induced IP3 formation and Ca2+ mobilization, a change of PKC activity was observed in TSMCs. PMA rapidly decreased PKC activity in the cytosol of TSMCs, while increasing it transiently in the membranes within 30 min. Thereafter the membrane-associated PKC activity decreased and persisted for at least 24 h of PMA treatment. Taken together, these results suggest that activation of PKC may inhibit the phosphoinositide hydrolysis and consequently attenuate the [Ca2+]i increase or inhibit independently both responses. The PMA-induced inhibition of responses to ET-1 was associated with an increase in membranous PKC activity.

Diode laser photocoagulation for retinopathy of prematurity

Recent studies have suggested that laser photocoagulation may be a favorable alternative to cryotherapy in the treatment of progressive extraretinal neovascularization in retinopathy of prematurity. Preliminary results of 10 eyes from 5 patients with so called "threshold" retinopathy of prematurity treated with indirect diode laser are reported. All 5 patients were less than 30 weeks gestational age. Laser therapy was performed on the avascular retina in both eyes. Nine eyes had one session of treatment with regression of neovascularization within 6 weeks. All eyes had good anatomical results in the posterior pole at the end of follow-up. One eye had 2 treatment sessions; neovascularization regressed after the second treatment. Mild disc dragging was noted. This report recommends the use of diode laser photocoagulation in the treatment of retinopathy of prematurity.

Pharmacological characterization of bradykinin receptors in canine cultured tracheal smooth muscle cells

1. [3H]-bradykinin was used to characterize the bradykinin receptors associated with canine cultured tracheal smooth muscle cells (TSMCs). Receptor binding assay showed that TSMCs had specific, saturable, high-affinity binding sites for [3H]-bradykinin. 2. The specific [3H]-bradykinin binding increased linearly with increasing cell concentrations. The equilibrium for association of [3H]-bradykinin with the bradykinin receptors was attained within 2 h at 4 degrees C and 1 h at room temperature, respectively. 3. Analysis of binding isotherms yielded an apparent equilibrium dissociation constant (KD) of 2.5 +/- 0.3 nM and a maximum receptor density (Bmax) of 25.1 +/- 0.3 fmol mg-1 protein. The Hill coefficient for [3H]-bradykinin binding was 1.00 +/- 0.02. The association (K1) and dissociation (K-1) rate constants were (8.67 +/- 2.60) x 10(6) M-1 min-1 and 0.024 +/- 0.005 min-1, respectively. KD, calculated from the ratio of K-1 and K1 was 2.8 +/- 0.5 nM, a value close to that of KD calculated from Scatchard plots of binding isotherms. 4. The B1 receptor selective agonist, (des-Arg9-bradykinin, 0.1 nM-10 microM) and antagonist ([Leu8, des-Arg9]-bradykinin, 0.1 nM-10 microM) did not did not inhibit the [3H]-bradykinin binding to TSMCs, which excludes the presence of B1 receptors in canine TSMCs. 5. The specific binding of [3H]-bradykinin to canine TSMCs was inhibited by B2 receptor selective antagonists ([D-Arg0, Hyp3, Thi5, D-Tic7, Oicl-bradykinin, Hoe 140, 0.1 nM-10 micro M and [D-Arg0, Hyp3,Thi5,8, D-Phe7-bradykinin, 0.1 nM-10 micro M) and agonists (bradykinin and kallidin, 0.1 nM-10 micro M) with a best fit by a one-binding site model. The order of potency for the inhibition of [3H]-bradykinin binding was kallidin = bradykinin = Hoe 140> [D-Arg0, Hyp3, Thi5,8, D-Phel-bradykinin.6. Preincubation of TSMCs with forskolin for 24 h led to an up-regulation of B2 receptors, increasing in Bmax from 25.1 +/- 0.3 to 218 +/- 24 fmol mg-1 protein without changing the KD values. [3H]-bradykinin binding to TSMCs was inhibited by the B2 receptor selective antagonists and agonists, but not by the B1 receptor selective reagents. The up-regulation of the B2 receptor by forskolin was mediated through protein synthesis, since cycloheximide blocked this response.7 It is concluded that the pharmacological characteristics of the bradykinin receptors in canine cultured TSMCs are primarily of the B2 receptor subtype.

Antimuscarinic action of liriodenine, isolated from Fissistigma glaucescens, in canine tracheal smooth muscle

1. The antimuscarinic properties of liriodenine, isolated from Fissistigma glaucescens, were compared with methoctramine (cardioselective M2 antagonist) and 4-diphenylacetoxy-N-methylpiperidine (4-DAMP, smooth muscle selective M3 antagonist) by radioligand binding tests, functional tests and measurements of second messenger generation in canine cultured tracheal smooth muscle cells. 2. Liriodenine, pirenzepine, methoctramine and 4-DAMP displaced [3H]-N-methyl scopolamine ([3H]-NMS) binding in a concentration-dependent manner with Ki values of 2.2 +/- 0.4 x 10(-6), 3.3 +/- 0.7 x 10(-7), 8.9 +/- 2.3 x 10(-8) and 2.3 +/- 0.6 x 10(-9) M, respectively. The curves for competitive inhibition of [3H]-NMS with liriodenine, methoctramine and 4-DAMP were best fitted according to a two site model of binding, but pirenzepine was best fitted according to a model with one site. 3. Liriodenine and 4-DAMP displayed a high affinity for blocking tracheal contraction (pKB = 5.9 and 9.1, respectively) and inositol phosphate formation (pKB = 6.0 and 8.9, respectively), but a low affinity for antagonism of cyclic AMP inhibition (pKB = 4.7 and 7.8, respectively). 4. Methoctramine blocked cyclic AMP inhibition with a high affinity (pKB = 7.4), but it antagonized tracheal contraction and inositol phosphate formation with a low affinity (pKB = 6.1 and 6.0, respectively). 5. In conclusion, both M2 and M3 muscarinic receptor subtypes coexist in canine tracheal smooth muscle and are coupled to the inhibition of cyclic AMP formation and phosphoinositide breakdown, respectively. The antimuscarinic characteristics of liriodenine are similar to those of 4-DAMP. It may act as a selective M3 receptor antagonist in canine tracheal smooth muscle.

Sarafotoxin-induced calcium mobilization in cultured dog tracheal smooth muscle cells

Sarafotoxin b (S6b)-induced changes in intracellular Ca2+ concentration ([Ca2+]i) were monitored in cultured canine tracheal smooth muscle cells (TSMCs) by a fluorescent Ca2+ indicator fura-2. S6b elicited an initial transient peak followed by a sustained elevation of [Ca2+]i. BQ-123, an endothelin-A (ETA) receptor antagonist, had a high affinity to block the rise in [Ca2+]i response to S6b. In the absence of external Ca2+, only an initial transient peak of [Ca2+]i was seen, the sustained elevation of [Ca2+]i could then be evoked by addition of 1.8 mM Ca2+. Ca2+ influx was required for the changes of [Ca2+]i, since the Ca(2+)-channel blockers, diltiazem, verapamil, and Ni2+, decreased both the initial and sustained elevation of [Ca2+]i in response to S6b. TSMCs pretreated with phorbol 12-myristate 13-acetate (PMA, 1 microM) for 30 min attenuated Ca2+ mobilization induced by S6b, which was reversed by staurosporine, a protein kinase C (PKC) inhibitor. The change of [Ca2+]i induced by S6b was attenuated by cholera toxin pretreatment, but not by pertussis toxin. These data demonstrate that the initial detectable increase in [Ca2+]i stimulated by S6b is due to the activation of ETA receptors and subsequent release of Ca2+ from internal stores, whereas the contribution of external Ca2+ follows and partially involves a diltiazem- and verapamil-sensitive process. The inhibition of PMA on S6b-induced Ca2+ mobilization was inversely correlated with membraneous PKC activity.

Experimental podophyllotoxin (bajiaolian) poisoning: III. Biochemical bases for toxic effects

The biochemical mechanism underlying the toxicity of podophyllotoxin is investigated. Previous studies from our laboratories suggested that hepatocytes were extremely sensitive to the toxicity of podophyllotoxin and a disruption of protein synthesis was suspected. Dose-response and time-course studies on the effects of podophyllotoxin on protein. RNA, and DNA syntheses on hepatocellular cultures were made. Inhibitions of protein, RNA, and DNA syntheses were demonstrated, and a direct correlated dose-response relationship on such effects was also evident. Inhibition of protein synthesis appeared to be a direct toxic effect of podophyllotoxin and occurred independently from that of RNA. The reduction of DNA synthesis was reflected by a reduction of H3-thymidine incorporation, which is believed to be the consequence of inhibition on the mitotic activity by podophyllotoxin.

Pancreatoblastoma: a case report

Primary neoplasms of the pancreas are rare in children. One variant of these tumors is pancreatoblastoma, comprising 0.5% of epithelial tumors of the pancreas. It usually affects children at 1-8 years of age, with quite equal sex ratio. The tumor can be found at any site of pancreas, but it most commonly arises in the head of pancreas. Histopathologically, pancreatoblastoma is an encapsulated tumor with distinct organoid structures and sometimes squamoid corpuscles. Acinar cells with zymogen granules are occasionally found. The tumor has favorable prognosis. We present a 14-year-old female who was admitted due to prolonged jaundice for about 2 months. Physical examination revealed pale conjunctiva, yellowish skin color and hepatosplenomegaly. Abdominal sonography and CT scan showed dilated common bile duct and a tumor mass about 2 x 2 cm in dimension located a pancreatic head. She received surgical operation to relieve obstructive jaundice and later Whipple's operation for radical resection. Six months after operation, the patient received the examination of abdominal sonography, CT scan and gallium tumor scan but there was no evidence of local recurrence or distant metastasis. Now the patient is living well for more than one year. Because of its rare occurrence, we demonstrate this case and review the literature.

5-Hydroxytryptamine-stimulated calcium mobilization in cultured canine tracheal smooth muscle cells

5-Hydroxytryptamine (5-HT)-induced increase of intracellular Ca2+ concentration ([Ca2+]i) was monitored in cultured canine tracheal smooth muscle cells (TSMCs) using a fluorescent Ca2+ indicator Fura-2. Stimulation of TSMCs by 5-HT produced an initial transient peak followed by a sustained, concentration-dependent elevation of [Ca2+]i. The log (EC50) values of 5-HT for the peak and sustained plateau responses were -7.43 and -7.60 M, respectively. 5-HT1A and 5-HT3 receptor antagonists, NAN-190 and metoclopramide, inhibited the 5-HT-stimulated increase in [Ca2+]i with pKB values of 6.3 and 6.2, respectively, indicating that the 5-HT receptors mediating Ca2+ signal had low affinity for these receptor antagonists. In contrast, 5-HT2A receptor antagonists, ketanserin and mianserin, had high affinity in antagonizing the changes in [Ca2+]i response to 5-HT with pKB values of 8.3 and 8.3, respectively. The sustained elevation of [Ca2+]i was dependent on the presence of extracellular Ca2+. Removal of extracellular Ca2+ by addition of 2 mM EGTA during the sustained phase caused a rapid decline in [Ca2+]i to the resting level. In the absence of extracellular Ca2+, only an initial peak was observed which then declined to the resting level; the sustained elevation of [Ca2+]i could then be evoked by addition of 1.8 mM Ca2+ in the continued presence of 5-HT. Ca2+ influx was required for the changes of [Ca2+]i, since the Ca(2+)-channel blockers, diltiazem, verapamil, and Ni2+, decreased both the initial and sustained elevation of [Ca2+]i in response to 5-HT. These Ca(2+)-channel blockers also decreased the sustained elevation of [Ca2+]i when applied during the plateau phase. In conclusion, these findings indicate that the initial increase in [Ca2+]i stimulated by 5-HT acting on 5-HT2A receptors is due to the release of Ca2+ from internal stores, followed by the influx of external Ca2+ into the cells. The influx of extracellular Ca2+ partially involves a diltiazem and verapamil sensitive Ca2+ channel.