PKC/MEK inhibitors suppress oxaliplatin-induced neuropathy and potentiate the antitumor effects

Oxaliplatin is a key drug commonly used in colorectal cancer treatment. Despite high clinical efficacy, its therapeutic application is limited by common, dose-limiting occurrence of neuropathy. As usual symptomatic neuropathy treatments fail to improve the patients' condition, there is an urgent need to advance our understanding of the pathogenesis of neuropathy to propose effective therapy and ensure adequate pain management. Oxaliplatin-induced neuropathy was recently reported to be associated with protein kinase C (PKC) activation. It is unclear, however, whether PKC inhibition can prevent neuropathy. In our current studies, we found that a PKC inhibitor, tamoxifen, inhibited oxaliplatin-induced neuropathy via the PKC/extracellular signal-regulated kinase (ERK)/c-Fos pathway in lumbar spinal cords (lumbar segments 4-6). Additionally, tamoxifen was shown to act in synergy with oxaliplatin to inhibit growth in tumor cells-implanted mice. Moreover, mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor, PD0325901, suppressed oxaliplatin-induced neuropathy and enhanced oxaliplatin efficacy. Our results indicate that oxaliplatin-induced neuropathy is associated with PKC/ERK/c-Fos pathway in lumbar spinal cord. Additionally, we demonstrate that disruption of this pathway by PKC and MEK inhibitors suppresses oxaliplatin-induced neuropathy, thereby suggesting that PKC and MEK inhibitors may be therapeutically useful in preventing oxaliplatin-induced neuropathy and could aid in combination antitumor pharmacotherapy.

[A search for the risk factors for hiccups and evaluation of antiemetic therapy in CDDP-based chemotherapy, using cluster analysis]

Hiccups are often observed in patients treated with cisplatin(CDDP)-based chemotherapy. It has been reported that gender and specific dosages of CDDP and antiemetic drugs(e.g., dexamethasone and 5-HT3 receptor antagonist)using standard therapy are major risk factors in the onset of hiccups. Recently, aprepitant has been added to the antiemetic therapy in CDDP-based chemotherapy. However, it is not known how the onset of hiccups takes place in antiemetic therapy including aprepitant according to the guideline. In this study, we used cluster analysis to classify 229 patients treated with CDDP-based chemotherapy, to investigate the effect of antiemetic therapy on the onset of hiccups and chemotherapy-induced nausea and vomiting(CINV). Our analysis indicated that aprepitant was not a major risk factor for the onset of hiccups in the high CDDP dose group(≥70 mg/m(2)). However, an effect of antiemesis was confirmed in the standard therapy with aprepitant. In conclusion, we suggest that aprepitant is effective for CINV, without causing the onset of hiccups in patients treated with high-dose CDDP-based chemotherapy.

Differential expression of the 5-HT(3A) and 5-HT(3B) receptor in differentiated NG108-15 cells

Previous work from this laboratory has shown that the serotonin (5-HT) induced response is significantly augmented in differentiated NG108-15 (NG) cells treated with dibutyryl cAMP (Bt(2)cAMP) due to qualitative and quantitative changes in the expression of the 5-HT(3) receptor as demonstrated by specific [(3)H] LY-278584 (a selective 5HT(3) receptor antagonist) binding. In this study, we investigated whether there is any change in the relative expression of the 5-HT(3A) and 5-HT(3B) subunits in NG cells differentiated following Bt(2)cAMP treatment cells. The major findings of this study were that the relative amount of 5-HT(3B) subunit mRNA in Bt(2)cAMP-treated NG cells 5 days following Bt(2)cAMP-treatment was greater than that in the untreated cells. In contrast, the relative expression of the 5-HT(3B) subunit protein in the Bt(2)cAMP-treated NG cells was much less than in the untreated cells, but the relative expression of the 5-HT(3A) subunit in the Bt(2)cAMP-treated NG cells was similar to the untreated cells. Therefore, no relationship between mRNA and protein expression for 5-HT(3A) and 5-HT(3B) subunits in Bt(2)cAMP treated and untreated NG cells were observed. It was also found that fluorescent intensity for the 5-HT(3B) subunit in the cell body of the Bt(2)cAMP treated and untreated NG cells gradually decreased from the day 1-5 after Bt(2)cAMP treatment. However, in specific areas such as the varicosity and nerve endings of the Bt(2)cAMP treated cells, staining intensity for the 5-HT(3B) subunits was stronger than in the untreated cells at the all time points, peaking at day 5 post-treatment. These results suggest that the augmented response induced by 5-HT acting via 5-HT(3) receptors in differentiated NG cells may be due to changes in the relative amount of the 5-HT(3B) subunit, particularly the ratio and distribution of the 5-HT(3A) to (3B) subunits.

Specific alternation of rhythm in temperature (SART) stress-induced irritable bowel syndrome-like changes in mice and effects of drugs

Stress is closely associated with the manifestation and progress of irritable bowel syndrome (IBS). For the purpose of establishing experimentally the relationship between IBS and stress, the transportation capacity of the small intestine in specific alternation of rhythm in temperature (SART)-stressed animals was studied using charcoal transportation method. The charcoal suspension was administered orally into the stomach of fasting mice. Mice were sacrificed after a certain time and %charcoal transit (%CT) of the small intestine was measured. The %CTs in SART-stressed mice were greater than those in unstressed or continuously cold-stressed mice. This increase in %CT remained for 1 week after discontinuation of SART stress loading. Cholinergic blockers decreased %CTs in SART-stressed mice. Increases in %CT by a cholinesterase inhibitor were less in SART-stressed mice than in unstressed mice. Increases of %CT in SART-stressed mice were suppressed by Neurotropine. These results suggested that the parasympathetic hypertonicity, not just cold, played a role in the increases in the transportation capacity in SART-stressed mice and that these animals can be a useful tool for elucidation of the mechanism of IBS.

Effects of the α1-adrenoceptor agonist phenylephrine on SART stress-induced orthostatic hypotension in rats

BACKGROUND

Specific alternation of rhythm in temperature (SART)-stressed rats, an animal model of autonomic imbalance, exhibit low blood pressure and tachycardia during consciousness and under anesthesia. In addition, these rats easily develop orthostatic hypotension (OH) as a response to postural manipulation. Hence, we studied the influence of the adrenalin α1-receptor agonist phenylephrine on stress-induced OH in SART-stressed rats and unstressed rats.

METHODS

Male Wistar rats weighing 250-300 g were used. Rats were fixed in the supine position under urethane anesthesia. Blood pressure was directly measured from the left common carotid artery and ECG was recorded simultaneously.

RESULTS

The maximum decrease in blood pressure and the area under the blood pressure-time curve were both large, while the %reflex was small in the SART-stressed rats compared with unstressed rats. In the SART-stressed rats, prolonged intravenous administration of phenylephrine reduced OH at a dose that barely affected unstressed rats.

CONCLUSION

The results suggested that sympathetic dysfunction is a factor underlying SART stress-induced OH.

Changes in characteristics of the specific binding of [3H]LY-278584, a 5-HT3-receptor antagonist, on differentiated NG108-15 cells

We have reported previously that the concentration of intracellular Ca2+ evoked by serotonin (5-HT) was significantly augmented in differentiated NG108-15 (NG) cells treated with dibutyryl cAMP and the enhanced response occurred via 5-HT3 receptors. We investigated changes in the characteristics for specific binding of [(3)H]LY-278584 (a specific antagonist of the 5-HT3 receptor) on membranes from differentiated NG cells. The results indicated that the K(d) and B(max) values for the specific binding to differentiated NG cells were significantly smaller and larger, respectively, than those for undifferentiated NG cells. The binding was significantly inhibited by 10 nM tropisetron, a specific 5-HT3-receptor antagonist, but not by any other types of 5-HT-receptor antagonists. These results suggested that the enhanced response by 5-HT in differentiated NG cells was due to both qualitative and quantitative changes in the 5-HT3 receptor.

Expression of metallothionein mRNAs on mouse cerebellum microglia cells by thimerosal and its metabolites

Effects of thimerosal and its metabolites, ethyl mercury and thiosalicylate, on the expression of metallothionein (MT) mRNAs in mouse cerebellum microglia cell line, C8-B4 cells, were studied. The level of MT-1 mRNA significantly decreased at early hours and recovered time-dependently 24h after thimerosal was added to the C8-B4 cells. However, MT-2 and MT-3 mRNA expressions did not change from the control group. In contrast, the expression of MT-1 mRNA increased in a mouse neuroblastoma cell line 6h after incubation with thimerosal. In addition, the level of MT-1 mRNA decreased in C8-B4 cells 6h after the addition of thiosalicylate, but ethyl mercury induced MT-1 mRNA expression. When cell viability was compared with thimerosal, thiosalicylate, and ethyl mercury, the viability of C8-B4 cells decreased dose-dependently 24h after either thimerosal or ethyl mercury was added; however, the viability increased dose-dependently until 15 microM thiosalicylate was added. From the present results, it is concluded that the expression of MT-1 mRNA may be mediated by different factors than the expression of MT-2 mRNA in C8-B4 cells. The reduction of MT-1 mRNA level by thiosalicylate may affect the proliferation of C8-B4 cells.

Induction of metallothionein in mouse cerebellum and cerebrum with low-dose thimerosal injection

Thimerosal, an ethyl mercury compound, is used worldwide as a vaccine preservative. We previously observed that the mercury concentration in mouse brains did not increase with the clinical dose of thimerosal injection, but the concentration increased in the brain after the injection of thimerosal with lipopolysaccharide, even if a low dose of thimerosal was administered. Thimerosal may penetrate the brain, but is undetectable when a clinical dose of thimerosal is injected; therefore, the induction of metallothionein (MT) messenger RNA (mRNA) and protein was observed in the cerebellum and cerebrum of mice after thimerosal injection, as MT is an inducible protein. MT-1 mRNA was expressed at 6 and 9 h in both the cerebrum and cerebellum, but MT-1 mRNA expression in the cerebellum was three times higher than that in the cerebrum after the injection of 12 microg/kg thimerosal. MT-2 mRNA was not expressed until 24 h in both organs. MT-3 mRNA was expressed in the cerebellum from 6 to 15 h after the injection, but not in the cerebrum until 24 h. MT-1 and MT-3 mRNAs were expressed in the cerebellum in a dose-dependent manner. Furthermore, MT-1 protein was detected from 6 to 72 h in the cerebellum after 12 microg/kg of thimerosal was injected and peaked at 10 h. MT-2 was detected in the cerebellum only at 10 h. In the cerebrum, little MT-1 protein was detected at 10 and 24 h, and there were no peaks of MT-2 protein in the cerebrum. In conclusion, MT-1 and MT-3 mRNAs but not MT-2 mRNA are easily expressed in the cerebellum rather than in the cerebrum by the injection of low-dose thimerosal. It is thought that the cerebellum is a sensitive organ against thimerosal. As a result of the present findings, in combination with the brain pathology observed in patients diagnosed with autism, the present study helps to support the possible biological plausibility for how low-dose exposure to mercury from thimerosal-containing vaccines may be associated with autism.

Characteristics for enhanced response of serotonin-evoked ion dynamics in differentiated NG108-15 cells

Characteristics for the up-regulated response in the concentration of intracellular calcium ion ([Ca(2+)]( i )) and in the sodium ion (Na(+)) current by serotonin (5-HT) were investigated in differentiated neuroblastoma x glioma hybrid NG108-15 (NG) cells. The results for the changes in [Ca(2+)]( i ) by 5-HT were as follows, (1) The 5-HT-induced Ca(2+) response was inhibited by 3 x 10(-9) M tropisetron (a 5-HT(3) receptor blocker), but not by other types of 5-HT receptor blockers; (2) The 5-HT-induced Ca(2+) response was mainly inhibited by calciseptine (a L-type Ca(2+) blocker), but not by other types of Ca(2+) channel blockers or 10(-7) M TTX (a voltage-sensitive Na(+) channel blocker); (3) When the extracellular Na(+) was removed by exchange with choline chloride or N-methyl-D-glucamine, the 5-HT-induced Ca(2+) response was extremely inhibited. The results for the 5-HT-induced Na(+) current by the whole cell patch-clamp technique were as follows, (1) The 5-HT-induced Na(+) current in differentiated cells was significantly larger than that in undifferentiated cells; (2) The ED(50) value for 5-HT-induced Na(+) current in undifferentiated and differentiated cells was almost the same, about 4 x 10(-6) M each other; (3) The 5-HT-induced Na(+) current was completely blocked by 3 x 10(-9) M tropisetron, but not by other 5-HT receptor antagonists and 10(-7) M TTX. These results suggested that 5-HT-induced Ca(2+) response in differentiated NG cells was mainly due to L-type voltage-gated Ca(2+) channels allowing extracellular Na(+) to enter via 5-HT(3) receptors, but not through voltage-gated Na(+) channels.

Hydrogen sulfide evokes neurite outgrowth and expression of high-voltage-activated Ca2+ currents in NG108-15 cells: involvement of T-type Ca2+ channels

We investigated if stimulation of T-type Ca(2+) channels with sodium hydrosulfide (NaHS), a donor of hydrogen sulfide (H(2)S), could cause neuronal differentiation of NG108-15 cells. Like dibutyryl cyclic AMP (db-cAMP), treatment with NaHS at 1.5-13.5 mM for 16 h enhanced neurite outgrowth in a concentration-dependent manner. Synergistic neuritogenic effect was obtained in the cells stimulated with NaHS in combination with db-cAMP at subeffective concentrations. Exposure to NaHS or db-cAMP for 2 days resulted in enhancement of expression of high-voltage-activated currents consisting of N-, P/Q-, L- and also other types, but not of T-type currents. Mibefradil, a pan-T-type channel blocker, abolished the neuritogenesis induced by NaHS, but not by db-cAMP. The NaHS-evoked neuritogenesis was also completely blocked by pretreatment with BAPTA/AM, a chelator of intracellular Ca(2+), and by zinc chloride at a concentration known to selectively inhibit Ca(v)3.2 isoform of T-type Ca(2+) channels, but not Ca(v)3.1 or Ca(v)3.3. Further, L-ascorbate, recently proven to selectively inhibit Ca(v)3.2, abolished the neuritogenic effect of NaHS, but not db-cAMP. Our data thus demonstrate that NaHS/H(2)S is a novel inducer of neuronal differentiation in NG108-15 cells, as characterized by neuritogenesis and expression of high-voltage-activated currents, and suggest the involvement of T-type Ca(2+) channels, especially Ca(v)3.2.

Enhancement of sodium current in NG108-15 cells during neural differentiation is mainly due to an increase in NaV1.7 expression

It is well known that morphological and functional changes during neural differentiation sometimes accompany the expression of various voltage-gated ion channels. In this work, we investigated whether the enhancement of sodium current in differentiated neuroblastoma x glioma NG108-15 cells treated with dibutyryl cAMP is related to the expression of voltage-gated sodium channels. The results were as follows. (1) Sodium current density on peak voltage in differentiated cells was significantly enhanced compared with that in undifferentiated cells, as detected by the whole-cell patch clamp method. The steady-state inactivation curve in differentiated cells was similar to that for undifferentiated cells, but a hyperpolarized shift in the activation curve for differentiated cells was observed. The sodium currents of differentiated and undifferentiated cells were completely inhibited by 10(-7) M tetrodotoxin (TTX). (2) The only Na(V) mRNA with an increased expression level during neuronal differentiation was that for NaV1.7, as observed by real-time PCR analysis. (3) The increase in the level of NaV1.7 alpha subunit expression during neuronal differentiation was also observed by immunocytochemistry; in particular, the localization of NaV1.7 alpha subunits on the soma, varicosities and growth cone was significant. These results suggest that the enhancement of TTX-sensitive sodium current density in differentiated NG108-15 cells is mainly due to the increase in the expression of the TTX-sensitive voltage-gated Na+ channel, NaV1.7.

Hydrogen sulfide as a novel nociceptive messenger

Hydrogen sulfide (H(2)S), an endogenous gasotransmitter, modulates various biological events such as inflammation in the mammalian body. The present study investigated possible involvement of H(2)S in peripheral nociceptive processing. Intraplantar (i.pl.) administration of NaHS, a H(2)S donor, produced prompt hyperalgesia in rats, accompanied by expression of Fos in the spinal dorsal horn. The H(2)S-evoked hyperalgesia was blocked by 5,5'-dithio-bis-(2-nitrobenzoic acid) (DTNB), an oxidizing agent, or ethosuximide and mibefradil, T-type Ca(2+) channel inhibitors. L-Cysteine, an endogenous source for H(2)S, given i.pl., also elicited hyperalgesia, an effect being abolished by DL-propargylglycine (PPG) and beta-cyanoalanine (BCA), inhibitors of cystathionine-gamma-lyase, a H(2)S synthesizing enzyme. PPG and/or BCA partially inhibited the hyperalgesia induced by i.pl. lipopolysaccharide, an effect being reversed by i.pl. NaHS. In the patch-clamp study using undifferentiated NG108-15 cells that express T-type, but not other types, of Ca(2+) channels, NaHS enhanced the currents through the T-type channels, an effect being blocked by DTNB. Thus, H(2)S appears to function as a novel nociceptive messenger through sensitization of T-type Ca(2+) channels in the peripheral tissues, particularly during inflammation.

Paclitaxel-2′-Ethylcarbonate Prodrug Can Circumvent P-glycoprotein-mediated Cellular Efflux to Increase Drug Cytotoxicity

PURPOSE

The aim of the study was to investigate whether 2'-ethylcarbonate-linked paclitaxel (TAX-2'-Et) circumvents P-glycoprotein (P-gp)-mediated cellular efflux and cytotoxicity enhanced by TAX-2'-Et activation within human culture cells transfected with a rabbit liver carboxylesterase (Ra-CES) cDNA.

MATERIALS AND METHODS

TAX-2'-Et transport was characterized in a human colon carcinoma cell line (Caco-2) and paclitaxel (TAX)-resistant ovarian carcinoma cells (SKOV3/TAX60). Expression of P-gp, multidrug resistance protein (MRP) 2 and Ra-CES was detected by Western blotting. Cytotoxicity against Ra-CES-expressing cells and cellular amount of TAX produced were determined by MTT assay and using HPLC, respectively.

RESULTS

Unlike rhodamine123 and TAX, TAX-2'-Et did not exhibit polarized transport in the Caco-2 cells in the absence or presence of verapamil. P-gp levels were expressed much higher in the SKOV3/ TAX60 cells than in the Caco-2 cells. MRP2 protein was not detectable in the SKOV3/TAX60 cells. Uptake by the SKOV3/TAX60 cells was similar in quantity to the amount internalized by P-gp-negative SKOV3 cells. In the SKOV3/TAX60 cells, cellular uptake of TAX-2'-Et was not altered regardless of the absence or presence of verapamil. The cytotoxicity to the untransfected SKOV3 cells induced by TAX-2'-Et was significantly lower than that induced by TAX. In the Ra-CES-expressing SKOV3 line, the EC50 value of TAX (10.6 nM) was approximately four-fold higher than that of TAX-2'-Et (2.5 nM). Transfection of Ra-CES into another TAX-resistant ovarian carcinoma cells (KOC-7c) conferred a high level of TAX-2'-Et cytotoxicity via prodrug activation. The intracellular levels of TAX produced from TAX-2'-Et in the Ra-CES-positive KOC-7c cells significantly increased compared with the levels seen in exposure of the untransfected KOC-7c cells to TAX.

CONCLUSIONS

TAX-2'-Et can circumvent P-gp-associated cellular efflux of TAX. TAX-2'-Et is converted into TAX by the Ra-CES, supporting its potential use as a theoretical GDEPT strategy for cancer cells expressing high levels of P-gp. The TAX-2'-Et prodrug efficiently increased the amount of intracellular TAX, which mediates tumor cell death.

Enhancement of serotonin- and bradykinin-evoked calcium ion dynamics in differentiated NG108-15 cells

Dynamic changes in the concentration of intracellular free-calcium ion ([Ca(2+)](i)) by carbachol (CCh) and neurotransmitter candidates was investigated in undifferentiated and differentiated neuroblastomaxglioma hybrid NG108-15 (NG) cells. [Ca(2+)](i) was increased in a dose-dependent manner by bradykinin (BK) and serotonin (5-HT) in differentiated NG cells, and the response to BK and 5-HT was significantly greater than that in undifferentiated NG cells. The EC(50) value of BK was approximately 1.5 x 10(-8)M in both undifferentiated and differentiated NG cells. The EC(50) value of 5-HT in differentiated NG cells was about 5 x 10(-6)M. The response to BK and 5-HT was almost completely inhibited by 10 nM Hoe140 (a BK B2 receptor antagonist) and 3 nM tropisetron (a 5-HT(3) receptor antagonist), respectively. These results suggest that there are some mechanisms by which the response evoked by BK and 5-HT is up-regulated in differentiated NG cells.

Enhancement of veratridine-induced sodium dynamics in NG108-15 cells during differentiation

Developmental changes in dynamics of Na+ were studied in neuroblastomaxglioma hybrid NG108-15 cells during differentiation which was induced by dibutyryl cAMP (Bt2cAMP). Ratiometric Na+ imaging with a Na+-sensitive fluorescent dye SBFI (sodium-binding benzofuran isophthalate) revealed that the intracellular Na+ concentration ([Na+]i) was not affected by the application of high K+ (60 mM) solution to either control or differentiated cells. When cells were exposed to 50 microM veratridine (Vtd), an agonist of voltage-sensitive sodium channels (VSSCs), a significant increase in [Na+]i was observed in differentiated but not in undifferentiated cells. Calculated mean [Na+]i value increased from the basal 10.4 to 44.1 mM in response to 50 microM Vtd. This Vtd response was reversibly inhibited by tetrodotoxin (TTX), a specific blocker for VSSCs, in a dose-dependent manner (IC50 = 1 nM). It is suggested that VSSCs in NG108-15 cells are sensitive to TTX and Vtd and that the number of VSSCs increases during differentiation.

Signal transduction for proteinase-activated receptor-2-triggered prostaglandin E2 formation in human lung epithelial cells

We investigated proteinase-activated receptor-2 (PAR(2))-triggered signal transduction pathways causing increased prostaglandin E(2) (PGE(2)) formation in human lung-derived A549 epithelial cells. The PAR(2) agonist, SLIGRL-NH(2) (Ser-Leu-Ile-Gly-Arg-Leu-amide), evoked immediate cytosolic Ca(2+) mobilization and delayed (0.5-3 h) PGE(2) formation. The PAR(2)-triggered PGE(2) formation was attenuated by inhibition of the following signal pathway enzymes: cyclooxygenases 1 and 2 (COX-1 and COX-2, respectively), cytosolic Ca(2+)-dependent phospholipase A(2) (cPLA(2)), the mitogen-activated protein kinases (MAPKs), mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK)-extracellular signal-regulated kinase (ERK) and p38 MAPK, Src family tyrosine kinase, epidermal growth factor (EGF) receptor tyrosine kinase (EGFRK), and protein kinase C (PKC), but not by inhibition of matrix metalloproteinases. SLIGRL-NH(2) caused prompt (5 min) and transient ERK phosphorylation, blocked in part by inhibitors of PKC and tyrosine kinases but not by an EGFRK inhibitor. SLIGRL-NH(2) also evoked a relatively delayed (15 min) and persistent (30 min) phosphorylation of p38 MAPK, blocked by inhibitors of Src and EGFRK but not by inhibitors of COX-1 or COX-2. SLIGRL-NH(2) elicited a Src inhibitor-blocked prompt (5 min) and transient phosphorylation of the EGFRK. SLIGRL-NH(2) up-regulated COX-2 protein and/or mRNA levels that were blocked by inhibition of p38 MAPK, EGFRK, Src, and COX-2 but not MEK-ERK. SLIGRL-NH(2) also caused COX-1-dependent up-regulation of microsomal PGE synthase-1 (mPGES-1). We conclude that PAR(2)-triggered PGE(2) formation in A549 cells involves a coordinated up-regulation of COX-2 and mPGES-1 involving cPLA(2), increased cytosolic Ca(2+), PKC, Src, MEK-ERK, p38 MAPK, Src-mediated EGF receptor trans-activation, and also metabolic products of both COX-1 and COX-2.

Effects of Calmodulin and Ca2+ Channel Blockers on ω-conotoxin GVI A Binding to Crude Membranes from α1B Subunit (Cav2.2) Expressed BHK Cells and Mice Brain Lacking the α1B Subunits

Characteristics for the specific binding of 125I-omega-CTX GVIA and 125I-omega-CTX MVIIC to crude membranes from BHKN101 cells expressing the alpha1B subunits of Cav2.2 channels and from mice brain lacking the alpha1B subunits of Cav2.2 channels, particularly, the effects of CaM and various Ca2+ channel blockers on these specific bindings were investigated. Specific binding of 125I-omega-CTX GVIA to the crude membranes from BHKN101 cells was observed, but not from control BHK6 cells. omega-CTX GVIA, omega-CTX MVIIC and omega-CTX SVIB inhibited the specific binding of 125I-omega-CTX GVIA to crude membranes from BHKN101 cells, and the IC50 values for omega-CTXGVIA, omega-CTX MVIIC and omega-CTX SVIB were 0.07, 8.5 and 1.7 nM, respectively. However, omega-agatoxin IVA and calciseptine at concentrations of 10(-9)-10(-6) M did not inhibit specific binding. Specific binding was also about 80% inhibited by 20 microg protein/ml CaM. The amount of 125I-omega-CTX GVIA (30 pM) specifically bound to membranes from brain of knockout mice lacking alpha1B subunits of Cav2.2 channels was about 30% of that to the crude membranes from brain of wild-type. On the other hand, specific binding of 125I-omega-CTX MVIIC (200 pM) was observed on the crude membranes of both BHKN101 and control BHK6 cells. The specific binding of 125I-omega-CTX MVIIC (200 pM) was not inhibited by omega-CTX GVIA and omega-CTX SVIB, and also omega-Aga IVA and calciseptine at concentrations of 10(-9)-10(-7) M, although specific binding was almost completely dose dependently inhibited by non-radiolabeled omega-CTX MVIIC (IC50 value was about 0.1 nM). 20 microg protein/ml CaM did not inhibit specific binding. Therefore, these results suggest that BHKN101 cells have a typical Cav2.2 channels which are also inhibited by CaM and have not specific binding sites for omega-CTX MVIIC, although omega-CTX MVIIC is a blocker for both Cav2.1 (alpha1A; P/Q-type) and Cav2.2 channels.

Characteristics of Omega-conotoxin GVI A and MVIIC Binding to Cav 2.1 and Cav 2.2 Channels Captured by Anti-Ca2+ Channel Peptide Antibodies

A New Binding Method (NBM) was used to investigate the characteristics of the specific binding of 125I-omega-conotoxin (omega-CTX) GVIA and 125I-omega-CTX MVIIC to Cav2.1 and Cav2.2 channels captured from chick brain membranes by antibodies against B1Nt (a peptide sequence in Car2.1 and Cav2.2 channels). The results for the NBM were as follows. (1) The ED50 values for specific binding of 125I-omega-CTX GVIA and 125I-omega-CTX MVIIC to Cav2.1 and Cav2.2 channels were about 68 and 60 pM, respectively, and very similar to those (87 and 35 pM, respectively) to crude membranes from chick brain. (2) The specific 125I-omega-CTX GVIA (100 pM) binding was inhibited by omega-CTX GVIA (0.5 nM), dynorphine A (Dyn), gentamicin (Gen), neomycin (Neo) and tobramicin (Tob) (100 microM each), but not by omega-agaconotoxin (Aga) IVA, calciseptine, omega-CTX SVIB, omega-CTX MVIIC (0.5 nM each), PN200-110 (PN), diltiazem (Dil) or verapamil (Ver) (100 microM each). Calmodulin (CaM) inhibited the specific binding in a dose-dependent manner (IC50 value of about 100 microg protein/ml). (3) The specific 125I-omega-CTX MVIIC (60 pM) binding was inhibited by omega-CTX MVIIC, omega-CTX GVIA, omega-CTX SVIB (0.5 nM each), Dyn, Neo and Tob (100 microM, each), but not by omega-Aga IVA, calciseptine (0.5 nM each), PN, Dil, Ver (100 microM each) or 100 microg protein/ml CaM. These results suggested that the characteristics of the specific binding of 125I-omega-CTX GVIA and 125I-omega-CTX MVIIC to Cav2.1 and Cav2.2 channels in the NBM were very similar to those to crude membranes from chick brain, although the IC50 values for CaM and free Ca2+ of CaM were about 33- and 5000-fold higher, respectively, than those for the specific binding of 125I-omega-CTX GVIA and 125I-omega-CTX MVIIC to crude membranes.

Antigen selectivity characteristic of polyclonal antibodies against omega-conotoxin GVIA and N-type voltage-dependent calcium channels

The antibodies against omega-conotoxin GVIA (omega-CTX GVIA; N-type voltage-dependent calcium channel [VDCC] blocker) and B1Nt (N-terminal segment [residues 1-13] of BI alpha1 subunits of VDCCs) were prepared, and the selectivity for each antigen omega-CTX GVIA and B1Nt was investigated. For the antigen selectivity of anti-omega-CTX GVIA antibody against omega-CTX GVIA, ELISA, and immunoprecipitation were used. The reactions for ELISA and immunoprecipitation were observed except when antibody IgG purified by Protein A-Sepharose CL-4B from nonimmunized serum (purified NI-Ab) was used. The specific reactions were inhibited by 10 nM omega-CTX GVIA, but not by omega-CTX SVIB (N-type VDCC blocker), omega-CTX MVIIC (N- and P-type VDCC blocker), or omega-Aga IVA (P-type VDCC blocker). For the antigen selectivity of the anti-B1Nt antibody, analyses by ELISA, immunoprecipitation, and Western blotting were conducted. The reactions were observed except when NI-Ab was used. The ELISA and immunoprecipitation reactions were inhibited by the antigen peptide B1Nt, and the IC50 values were about 1.2 x 10(-8) and 1.3 x 10(-8) M, respectively. The bands of 210 and 190 kD by Western blotting of crude membranes from chick brain were also inhibited by 1 microM B1Nt. These results suggest that the antibodies prepared against omega-CTX GVIA and B1Nt in this work have high selectivity for their antigen. Therefore we assume that the antibodies against omega-CTX GVIA and B1Nt are useful tools for the analyses of the function and distribution of N-type VDCCs. The anti omega-CTX GVIA antibody must also be useful for the radioimmunoassay of omega-CTX GVIA.

A confirmation of 125I-omega-conotoxin labeled sites in a crude membrane fraction from chick brain as the alpha1 subunit of N-type calcium channels

Omega-conotoxin GVIA (omega-CTX), as a selective blocker for an N-type Ca2+ channel, has been conveniently used in many molecular biochemical and pharmacological experiments. There has been little elucidation of 125I-omega-CTX binding sites (mainly the 135-kDa band) in the crude membranes from chick brain, although the characteristics of specific 125I-omega-CTX binding and labeling sites in chick brain membranes have been investigated in our previous research. In this work, our goal is to further identify 125I-omega-CTX labeling sites in chick brain membranes by using anti-B1Nt antibodies (against the N-terminal segment B1Nt of N- or P-type Ca2+ channel alpha1-subunits). The 25I-omega-CTX-labeled sites in chick brain membranes could be solubilized and immunoprecipitated by using an anti B1Nt antibody. The molecular weight of the immunoprecipitated protein was determined as 135 kDa, which is inconsistent with that of the specific 125I-omega-CTX binding protein reported previously. Moreover, the 125-omega-CTX-labeled protein could be purified by the method of preparative SDS-PAGE and recognized by anti-B1Nt antibodies in Western blotting analysis. These results indicated that anti-B1Nt antibodies could truly recognize 125I-omega-CTX-labeled sites as the main band of 135 kDa from chick brain membranes, and the omega-CTX-labeled site (mainly the 135-kDa band) should be N-type Ca2+ channel alpha1-subunits.

Study of metallothionein using capillary zone electrophoresis

Metallothioneins (MTs) have many different functions in tissues, but the roles of individual isoforms are still not entirely clear. Capillary zone electrophoresis (CZE) is a powerful method for the separation of substances because of its small sample requirement, rapid analysis, high sensitivity and high resolution. The separation and identification of mammalian MT-1, MT-2, and MT-3 and class III MTs by CZE has been reported. Uncoated and polyacrylamide-coated capillary tubes were recently used for the separation of MTs, and a UV detector is usually employed for observations of peaks of MTs. Small changes to the structure and metal components of MTs are reflected in the migration times of the peaks. N-acetylated and non-acetylated MTs can be separated and identified by CZE-mass spectrometry (MS). In addition, metal complexes with MTs can be characterized by CZE-proton-induced X-ray emission (PIXE) detector and CZE-inductively coupled plasma (ICP)-MS. For the quantification of an MT isoform, the peak area of UV absorption is used, but the technique has problems. One is lack of a purified isoform standard. The other is the need for a suitable internal standard substance. CZE-ICP-isotope dilution (ID)-MS is also reported to be able to quantify MT isoforms. CZE combined with other techniques is very effective for separation and quantitative and qualitative analyses of MT isoforms in biological materials.

Determination of metallothionein-1/metallothionein-2 ratios in the mouse liver and pancreas by capillary zone electrophoresis using a polyacrylamide-coated capillary at neutral pH

Metallothionein (MT) isoforms, MT-1 and MT-2, in biological specimens are clearly separated by capillary zone electrophoresis (CZE) using a polyacrylamide-coated capillary. The effectiveness of CZE analysis in the study of MT isoforms in biological specimens is discussed. We did two experiments to determine the MT-1/MT-2 ratio in biological specimens. The ratio of MT-1/MT-2 can be determined by CZE under a neutral pH without any detergents. One of these studies is time-dependent changes of the MT-1/MT-2 ratio in the cytosol of the pancreas and liver in mice after Zn or Cd injection. In the pancreas, both isoforms were detected in the control mice and the ratio of MT-1/MT-2 was below 1.0. When Zn was injected, the maximum peak areas of both isoforms were obtained at 24 h, and the ratios increased over a value of 1.0 at 3 h and peaked at 10 h. However, in the Cd-injected mice, the peak areas of both isoforms increased up to 72 h, and the ratios were below 1.0 up to 72 h. On the contrary, neither isoform was detected in the livers of control mice. The ratios of Zn-injected mice liver were near the value 1.0 between 6 and 72 h, although the areas of both isoforms showed peaks at 48 h. The ratios of Cd-injected mice livers were detected to be over 1.0 from 10 h, but there were no significant difference between 10 and 72 h, and the areas of both isoforms showed peaks at 24 h. The other experiment investigated the ratio in each fraction of cell fractionation. Cell fractionation was done in the livers of Zn-treated mice. Twenty-four hours after the injection, the ratio of MT-1/MT-2 was 0.80+/-0.12 and 1.19+/-0.21 (mean+/-SD) in nuclear and cytosol fractions, respectively. Neither isoform was detected in mitochondrial or microsomal fraction. From the present results, CZE analysis is a suitable method for observation of the ratio of MT-1/MT-2 in biological specimens, and dynamic changes in both isoforms can be detected.

Gender difference regarding selenium penetration into the mouse brain

A sex difference in the penetration of selenium into the brain was observed using lipopolysaccharide (LPS)-injected mice. The selenium concentration increased in the brains of sodium selenite-injected LPS-treated female mice, but not males. The selenium concentration peaked when selenite was injected 3 h after the injection of LPS into female mice. In addition, selenium in the brain increased when a dosage of 30 micromol/kg and more of selenite was injected into LPS-treated female mice. Also, the selenium concentration in the brain increased and peaked 2-3 h after selenite injection; 24 h later, the level was similar to the Se-only group. The penetration of selenium into the brain was inhibited by pretreatment with aminoguanidine, an inhibitor of nitric oxide synthetase. From the present results, selenium more easily penetrated into the brains of female mice compared to males after LPS treatment, and nitric oxide may have affected the penetration. However, the sex difference mechanism for selenium penetration needs further investigation.

UT841 purified from sea urchin (Toxopneustes pileolus) venom inhibits time-dependent (45)Ca(2+) uptake in crude synaptosome fraction from chick brain

To clarify the mechanism by which the toxic abstract from Toxopneustes pileolus inhibits time-dependent (Time-dep.) Ca(2+) uptake in crude synaptosome fraction, the effective component from pedicellarial venom of the sea urchin was purified. The crude extracts were purified by a series of steps including ion exchange (DEAE-sephadex-A25 gel), gel filtration (with Superdex-2000 and Superdex-peptide columns) and reversed-phase chromatography (Sephasil-C18 column). The effective component that inhibited Time-dep. 45Ca(2+) uptake was purified and named UT841. Its IC(50) was determined to be lower than 35ng/ml. UT841 is an acidic protein with an apparent molecular weight of about 18,000. The N-terminal sequence (40 amino acids) was almost identical to that of Contractin A (a protein purified from the same kind of venom which induces smooth muscle contraction). Even though it is unclear whether or not UT841 is Contractin A, Ca(2+) mobilization in nerve cells was shown to be influenced by UT841. This investigation also revealed that a donor of nitric oxide, arachidonic acid and an inhibitor of phospholipase C selectively inhibit Time-dep. (45)Ca(2+) uptake. These results suggest that UT841 purified from sea urchin venom may affect Time-dep. (45)Ca(2+) uptake through the metabolism of some lipids and nitric oxide.

Pancreatic exocrine damage induced by subcutaneous injection of a low dosage of zinc

The aim of this study was to observe whether a low dosage of zinc induced mouse pancreatic injury. Dosages of zinc from 0.1 to 50 mg/kg were injected subcutaneously in mice, and plasma and pancreatic clinical parameters were observed 3-24 h after the injection. Plasma alpha-amylase activity increased 10 and 24 h after the injection of 25 or 50 mg/kg of zinc, whereas pancreatic alpha-amylase activity decreased 3 h after more than 5 mg/kg of zinc was injected. The activity recovered after 24 h except in the group injected with 50 mg/kg of zinc. The plasma glucose level did not change when less than 25 mg/kg of zinc was injected. The pancreatic zinc contents increased 3 h after more than 1 mg/kg of zinc was injected. The pancreatic metallothionein (MT) contents increased 6 h after the injection of 1 mg/kg of zinc. In addition, when more than 5 mg/kg of zinc was injected, the MT content increased at 3 h. In histochemical observations, cell damages such as fibrosis and necrosis were observed in pancreatic exocrine cells, but not in cells of Langerhans islets. From the present study, a single injection of a low dosage of zinc induces injury in pancreatic exocrine cells, but not endocrine cells.

Characteristics of the inhibitory effect of calmodulin on specific [125i]omega-conotoxin GVIA binding to crude membranes from chick brain

The characteristics of the inhibitory effect of calcium ion (Ca2+)/calmodulin (CaM) on specific [125I]-omega-conotoxin GVIA (125I-omega-CTX) binding and on the labeling of 125I-omega-CTX to crude membranes from chick brain were investigated. The inhibitory effect of Ca2+/CaM depended on the concentrations of free Ca2+ and CaM. The IC50 values for free Ca2+ and CaM were about 2.0 x 10(-8) M and 3.0 microg protein/ml, respectively. The inhibitory effect of Ca2+/CaM was attenuated by the CaM antagonists W-7, prenylamine and CaM-kinase II fragment (290-309), but not by the calcineurin inhibitor FK506. Ca2+/CaM also inhibited the labeling of a 135-kDa band (which was considered to be part of N-type Ca2+ channel alpha1 subunits) with 125I-omega-CTX using a cross-linker. These results suggest that Ca2+/CaM affects specific 125I-omega-CTX binding sites, probably N-type Ca2+ channel alpha1 subunits, in crude membranes from chick whole brain.

Calcium/calmodulin inhibits the binding of specific [125I]omega-conotoxin GVIA to chick brain membranes

The effect of Ca2+/calmodulin (CaM) on the specific binding of [125I]omega-conotoxin GVIA (125I-omega-CTX) to crude membranes from chick brain was investigated. When we examined the effects of the activation of various endogenous protein kinases on specific [125I]omega-CTX binding to crude membranes, we observed that Ca2+/CaM had an inhibitory effect regardless of whether or not the standard medium contained ATP (0.5 mM). Ca2+/CaM also had an inhibitory effect in a simple binding-assay medium containing HEPES-HCl buffer, BSA, Ca2+ and CaM, and this effect was dependent on the concentration of Ca2+. The effect of Ca2+/CaM was attenuated by the CaM antagonists W-7 and CaM-kinase II fragment (290-309). An experiment with modified ELISA using purified anti omega-CTX antibody indicated that Ca2+/CaM did not affect the direct binding of [125I]omega-CTX and CaM. These results suggest that Ca2+/CaM either directly or indirectly affects specific [125I]omega-CTX binding sites, probably N-type Ca2+ channels in crude membranes from chick whole brain.

Inhibitory effects of tetrahydroisoquinoline derivatives on Ca2+ and Na+ channels in crude nerve endings

Semi-synthetic tetrahydroisoquinoline derivatives prepared from natural alkaloids, possess Ca2+ antagonistic properties. These derivatives significantly blocked KCl-stimulated Ca2+ uptake (In chick and rat crude nerve endings) which can be partially inhibited by the selective N-type Ca2+ channel blocker omega-conotoxin GVIA or the selective P-type Ca2+ channel blocker omega-agatoxin IVA. Moreover, PX42 (10 microM; for the tetrahydroisoquinoline compounds in this study) could inhibit the activity of calmodulin-dependent phosphodiesterase and block veratridine-induced (or tetrodotoxin-sensitive) Na+ uptake. The possible mechanism(s) of non-selective inhibition of ion channels of PX42 is discussed.

The inhibitory effect of the toxic fraction from sea urchin (Toxopneustes pileolus) venom on 45Ca2+ uptake in crude synaptosome fraction from chick brain

The effects of toxic peaks (P-I, P-II and P-III eluted from Sephadex G-200 column) from the sea urchin Toxopneustes pileolus on time-dependent 45Ca2+ uptake in chick P2 fraction (crude synaptosome fraction) were studied under physiological ionic conditions. Time-dependent 45Ca2+ uptake was inhibited by P-II and P-III, but not by P-I. P-II had the greatest inhibitory effect. The inhibitory effect of P-II was not due to the inhibition of 45Ca2+ binding on P2 fraction, because P-II did not affect 45Ca2+ binding in osmotic-shocked P2 fraction. P-II did not affect KCl-stimulated 45Ca2+ uptake in P2 fraction, (Ca(2+)-Mg2+)-ATPase activity in the synaptic plasma membrane (SPM) fraction, or (Na(+)-K+)-ATPase and Mg(2+)-ATPase activities in osmotically-shocked P2 fraction. In contrast, the Na+/Ca2+ exchanger blocker 2',4'-dichlorobenzamil (DCB; 100 microM), with a poor specificity, inhibited not only time-dependent 45Ca2+ uptake but also KCl-stimulated 45Ca2+ uptake, (Ca(2+)-Mg2+)-ATPase, Mg(2+)-ATPase and (Na(+)-K+)-ATPase. Involvement of Na(+)-Ca2+ exchanger in the time-dependent 45Ca2+ uptake was ruled out, since it was not inhibited by replacement of Na+ with Li+ in reaction medium. These results suggested that the inhibition by P-II on time-dependent 45Ca2+ uptake appeared to be more specific than the commercially available Na+/Ca2+ exchanger blocker DCB, although the mechanism is not clear yet.

A toxic extract from sea urchin (T. pileolus) inhibits 45Ca2+ uptake in P2 fraction from chick brain under physiological ionic conditions

An acidic toxic extract from the sea urchin T. pileolus inhibited time-dependent 45Ca2+ uptake in chick P2 fraction (IC50 about 10 ng/ml). This toxic extract is susceptible to trypsin. The inhibitory effect probably relate to Na+/Ca2+ exchanger.

Proportions of Ca2+ channel subtypes in chick or rat P2 fraction and NG108-15 cells using various Ca2+ blockers

The proportions of calcium (Ca2+) channel subtypes in chick or rat P2 fraction and NG 108-15 cells were investigated using selective L-, N-, P- and P/Q- type Ca2+ channel blockers. KCl-stimulated 45Ca2+ uptake by chick P2 fraction was blocked by 40-50% using N-type Ca2+ channel blockers [omega-conotoxin GVIA, aminoglycoside antibiotics and dynorphin A(1-13)], but was not inhibited by P- or P/Q-type blockers (omega-agatoxin IVA or omega-conotoxin MVIIC). On the other hand, KCl-stimulated 45Ca2+ uptake by rat P2 fraction was blocked by 30 approximately 40% using P- or P/Q-type Ca2+ channel blockers, but was not inhibited by N-type Ca2+ channel blockers. The L-type Ca2+ channel blockers 1,4-dihydropyridines, diltiazem and verapamil, but not calciseptine (CaS), inhibited both KCl-stimulated 45Ca2+ uptake and veratridine-induced 22Na+ uptake by chick or rat P2 fraction with similar IC50 values. CaS did not have any effect on 45Ca2+ uptake by either chick or rat P2 fraction. In NG108-15 cells, CaS, omega-agatoxin IVA and omega-conotoxin MVIIC, but not omega-conotoxin GVIA, inhibited KCl-stimulated 45Ca2+ uptake by 30-40%. Various combinations of these Ca2+ channel blockers had no significant additional effects in chick or rat P2 fraction or NG 108-15 cells. These findings suggest that KCl-stimulated 45Ca2+ uptake by chick or rat P2 fraction and NG 108-15 cells is a convenient and useful model for screening whether or not natural or synthetic substances have selective effects as L-, N-, P-, or P/Q- type Ca2+ channel antagonists or agonists.

Relationship between specific binding of 125I-omega-conotoxin GVIA and GTP binding protein: effects of the GTP analogues, mastoparan and A1F4-

We investigated whether the specific binding or labeling of 125I-omega-CgTX on crude membranes from chick whole brain was affected when endogenous GTP binding protein (G protein) was activated by GTP analogues, mastoparan (MP) and aluminum fluoride (AIF4-; AICl3 + NaF). Both GTPgammaS and Gpp(NH)p attenuated the inhibitory effect of selective N-type Ca channel inhibitors such as aminoglycoside antibiotics (AGs) or dynorphine (1-13)(Dyn) on specific 125I-omega-CgTX binding in a dose-dependent manner. On the other hand, the inhibitory effects of the divalent metal cations Cd2+, Co2+, Mg2+ and Mn2- on such binding were not attenuated by GTPgammaS. MP and AIF4- also attenuated the inhibitory effect of Neo on this binding similar to GTPgammaS. The attenuating effect of MP was enhanced by the presence of Mg2+ in a dose-dependent manner. However, GTP analogues, MP and AIF4-, did not affect binding or labeling without AGs or Dyn. GTPgammaS, MP and AIF4- also attenuated the specific labeling of a 215-kDa band in crude membranes with 125I-omega-CgTX using the cross-linker DSS (non-reduced condition) in the presence of Neo. These results indicate that there are direct or indirect relationships between N-type Ca channels and G proteins via binding sites for AGs or MP.

Binding and labeling of omega-conotoxin GVIA in crude membranes from subfractionated fractions and various areas of chick brain

Specific binding and specific labeling of 125I-omega-CgTX were investigated in crude membranes from both subfractionated fractions and various brain areas in chick whole brain. The specific activities of the marker enzymes 2',3'-cyclic nucleotide 3'-phosphorylase, Na/K ATPase and succinic dehydrogenase in the subfractionated fractions were three- to five-fold higher than those in the P2 fraction. However, the amount of specific [125I] omega-CgTX binding in the fractions of synaptosomes and synaptic plasma membranes was only about 1.2-times higher than that in the P2 fraction. The characteristics of specific 125I-omega-CgTX labeling with disuccinimidyl suberate to the 135-kDa band were generally comparable to those of specific [125I] omega-CgTX binding sites. These results suggest that the specific binding sites of [125I] omega-CgTX were not localized the synaptosomes and synaptic plasma membranes fractions, although each fraction was well isolated from the others from which were decided by the strength of specific activity for marker enzymes.

Pathogenic significance of interleukin-6 in a patient with antiglomerular basement membrane antibody-induced glomerulonephritis with multinucleated giant cells

We report a patient with anti-glomerular basement membrane disease who developed renal failure associated with systemic manifestations, including acute-phase inflammatory reactions and plasmacytosis. Renal tissue obtained by an open surgical biopsy showed circumferential cellular crescents, multinucleated giant cells, and exudation of fibrin in all glomeruli. Immunofluorescence microscopy demonstrated deposition of immunoglobulin G, C3, and membrane attack complex along glomerular capillary walls. Multinucleated giant cells were suggested to be macrophage-monocyte lineage because they were CD68 positive. Bone marrow aspiration showed an increase of plasma cells. Immunostaining showed intensive expression of interleukin-6 (IL-6) in practically every part of the renal sites involving multinucleated cells, crescents, tubules, and infiltrating cells, suggesting that one of the sources of systemically elevated IL-6 was the kidney. Serum IL-6, anti-glomerular basement membrane antibody, and acute-phase proteins were markedly elevated, and returned dramatically to the normal level after corticosteroid therapy and plasmapheresis. We believe that IL-6 played an important role in the development of many symptoms in the present case.

Characteristics of [125I]omega-conotoxin labeling using bifunctional cross linker DSP in crude membranes from chick brain

Characteristic of [125I]omega-conotoxin (omega-CgTX) labeling using bifunctional cross linker (dithio bis[succinimidyl propionate]:DSP) was systematically investigated in crude membranes from chick whole brain. [125I]omega-CgTX specifically labeled 216 kDa as a main and 236 kDa as a minor bands in the crude membranes under non-reduced condition, but not labeled under reduced condition. We investigated the effect of various Ca channel antagonists on [125I]omega-CgTX labeling with DSP in detail, and found that there is a strong correlation between the effects of Ca channel antagonists on [125I]omega-CgTX labeling of the 216 kDa band and specific [125I]omega-CgTX binding. These results suggest that labeling of the 216 kDa band under non-reduced condition with [125I]omega-CgTX using DSP involves the specific binding sites of [125I]omega-CgTX, perhaps including one of the neuronal N-type Ca channel subunits in the crude membranes.

Characteristics of specific 125I-omega-conotoxin GVIA binding and 125I-omega-conotoxin GVIA labeling using bifunctional crosslinkers in crude membranes from chick whole brain

Characteristics of specific 125I-omega-conotoxin GVIA (125I-omega-CgTX) binding and 125I-omega-CgTX labeling using bifunctional crosslinkers were systematically investigated in crude membranes from chick whole brain. Aminoglycosides and dynorphine A (1-13) inhibited the specific binding of 125I-omega-CgTX, but not that of the L-type calcium ion channel antagonist [3H](+)PN200-110. It seems likely that the inhibitory effect of dynorphine A (1-13) does not involve kappa-opiate receptors, based on results with the opiate receptor antagonist naloxone and the kappa-opiate receptor agonist U50488H. Spider venom, Cd2+ and La3+ inhibited the specific binding of 125I-omega-CgTX, as well as that of [3H](+)PN200-110. Various L-type Ca2+ channel antagonists did not affect the specific binding of 125I-omega-CgTX. 125I-omega-CgTX specifically labeled 135 kDa and 215 kDa bands in crude membranes under reduced and non-reduced conditions, respectively. The crosslinker disuccinimidyl suberate (DSS) yielded better 125I-omega-CgTX labeling than the other two crosslinkers tested. We investigated the effect of various Ca2+ channel antagonists on 125I-omega-CgTX labeling with DSS in detail, and found that there is a strong correlation between the effects of Ca2+ channel antagonists on 125I-omega-CgTX labeling of the 135 kDa band and specific 125I-omega-CgTX binding. These results suggest that aminoglycosides and dynorphine A (1-13) are specific inhibitors of specific 125I-omega-CgTX binding, and that labeling of the 135 kDa band with 125I-omega-CgTX using DSS involves the specific binding sites of 125I-omega-CgTX, perhaps including one of the neuronal N-type Ca2+ channel subunits in the crude membranes.

In vivo effects of monoclonal antibodies that functionally inhibit complement regulatory proteins in rats

The present work was designed to evaluate the effects of functional suppression of complement regulatory proteins in vivo. Male Wistar rats were anesthetized with Nembutal and were intravenously injected with 1 mg/kg of F(ab')2 or Fab fraction of either monoclonal antibody 5I2, which inhibits the function of rat counterpart of mouse Crry/p65, or monoclonal antibody 6D1, which inhibits the rat counterpart of CD59. Mean arterial pressure was continuously measured for 30 min. When 5I2 was injected, there was a biphasic change of mean arterial pressure, namely, the rapid increase immediately after the injection (approximately 2 min, phase 1) and the subsequent fall and slow recovery (approximately 4-30 min, phase 2). These effects were completely abrogated by pretreatment of rats with cobra venom factor. Pretreatment with carboxypeptidase inhibitor, which inhibits inactivation of anaphylatoxins C3a and C5a, induced enhanced reduction of blood pressure. Circulating leukocytes and platelets were rapidly decreased 5 min after antibody injection and became normal by 2 h. Hematocrit and erythrocyte count were continuously increased up to 2 h after injection, suggesting that there was hemoconcentration due to increased vascular permeability. Immunofluorescence study revealed binding of antibody fragments and rat C3 along the capillaries of lung, heart, and liver 5 min after injection. In contrast to 5I2, F(ab')2 fraction of 6D1, though localized to the same areas and in similar amounts, had no significant effect on the parameters measured. These data suggest that the rat counterpart of mouse Crry/p65 plays a vital role in vivo by preventing the activation of autologous complement on vascular endothelium.

A case of renal sarcoidosis showing central necrosis and abnormal expression of angiotensin converting enzyme in the granuloma

We describe a 66-year-old man who developed renal failure related to granulomatous renal sarcoidosis without systemic manifestations. Renal failure was severe enough to require hemodialysis transiently. Renal biopsy of this patient revealed the central necrosis of the granuloma which is usually absent in sarcoid granuloma. Serum level of angiotensin converting enzyme (ACE) was not helpful for diagnosis in this patient because serum ACE level is often elevated in the condition of chronic renal failure. Immunohistochemical detection of ACE was of diagnostic value in this patient. Subsequent course in which glucocorticoid was used for therapy was consistent with the diagnosis. This is the first report of identification of ACE in renal sarcoid granuloma.

Localization of the complement regulatory proteins in the normal human kidney

The kidney is an organ where complement-mediated tissue injuries take place by various stimuli. To assess how the kidney is protected from the autologous complement attack, comparative localization of decay accelerating factor (DAF), membrane cofactor protein (MCP) and 20 kDa homologous restriction factor (HRF20) was studied in the normal human kidney. Specific monoclonal antibodies to DAF, MCP and HRF20 were used for the study. Studies by immunofluorescence and immunoelectron microscopy showed that the distribution of each protein in the kidney was complementary to each other in most parts. MCP and HRF20 were clearly seen in the glomerular capillaries, while DAF was only faintly observed. Juxtaglomerular apparatus was abundant in DAF and MCP but not in HRF20. HRF20 was most strongly expressed in the peritubular capillaries where MCP was not detectable. Basolateral membranes of the proximal tubules and collecting ducts expressed MCP strongly, while there was no expression of DAF in the proximal tubules. Interestingly, both DAF and MCP, which inhibit complement activation at C3/C4 level, were not expressed in the apical portion of the tubular cells including proximal tubule brush border. In contrast, HRF20 was expressed on the apical part of the tubules. Medullary interstitium strongly expressed MCP but not DAF. Based on these observations, we conclude that each segment of the kidney is protected from the complement attack by the different combination of complement regulatory proteins. We speculate that the tubular cells might be fragile when complements are activated inside the tubular lumen, because there is no expression of complement regulatory proteins which inhibit C3 convertase.

Effects of Ca channel agonists on 45Ca uptake differ depending on the state of NG108-15 cells

We investigated the effects of various Ca channel agonists (Ca agonist) derived from 1,4-dihydropyridine on KCl-stimulated 45Ca uptake by differentiated and undifferentiated neuroblastoma x glioma hybrid NG108-15 cells with and without dibutyryl cAMP. Ca agonists Bay K 8644, YC-170 and CGP 28392 enhanced KCl-stimulated 45Ca uptake in differentiated NG108-15 cells, but only slightly in undifferentiated NG108-15 cells. The rank order of the enhancing effects was roughly Bay K 8644 > YC-170 > > CGP 28392. These results suggest that there is some difference between the mechanism by which these Ca agonists affect KCl-stimulated 45Ca uptake in differentiated and undifferentiated NG108-15 cells, although the nature of that difference is not clear.

Characteristics of specific 125I-omega-conotoxin GVIA binding in rat whole brain

Characteristics of specific 125I-omega-conotoxin (omega-CgTX) binding were systematically investigated in crude membranes from rat whole brain. Kd and Bmax Values for the binding were 49.7 pM and 181.5 fmol/mg of protein, respectively. The effects of various types of Ca channel antagonists on the binding were investigated. Dynorphin A (1-13), in particular, specifically inhibited 125I-omega-CgTX binding, but not that of [3H](+)PN200-110. Spider venom from Plectreurys tristes did not specifically inhibit specific binding of 125I-omega-CgTX, because the venom also inhibited the binding of [3H](+)PN200-110 to a similar degree. The amount of specific binding of 125I-omega-CgTX was less in the cerebellum than that in any other area of whole brain. The cross-linker disuccinimidyl suberate did not label with 125I-omega-CgTX and its binding sites in rat whole brain, although it did in chick whole brain, which was used as a positive control. These findings suggested that dynorphine A (1-13) was a selective blocker of omega-CgTX-sensitive Ca channels in crude membranes from rat whole brain and that omega-CgTX-sensitive Ca channels were mainly present a rat brain except cerebellum.

Specific bindings of [3H](+)PN200-110 and [125I]omega-conotoxin to crude membranes from differentiated NG108-15 cells

The characteristics of the specific bindings of [3H](+)PN200-110 (PN: L-type Ca channel antagonist) and [125I]omega-conotoxin G VI A (omega-CgTX: neuronal L- or N-type Ca channel antagonist) to crude membranes from undifferentiated neuroblastoma X glioma hybrid NG108-15 (NG108-15) cells and differentiated cells induced with dibutyryl cAMP (Bt2cAMP) were examined, because we have already observed that the magnitude and rate of KCl-stimulated 45Ca uptake by NG108-15 cells increased progressively during differentiation of the cells induced with Bt2-cAMP (unpublished results). The specific binding of [3H](+)PN to these crude membranes was saturable at various concentrations of 2.5-5.0 nM [3H](+)PN. Scatchard analysis showed that the specific binding of [3H](+)PN at equilibrium was significantly increased after differentiation of the NG108-15 cells with Bt2cAMP, but that the apparent Kd value for the specific binding of [3H](+)PN was not influenced by treatment with Bt2cAMP. The specific binding of [3H](+)PN to crude membranes from Bt2cAMP-treated NG108-15 cells was inhibited by a calcium agonist and antagonists, the order of their inhibitory potencies being (+)PN > nitrendipine > (-)PN > or = Bay K 8644 > > diltiazem = verapamil. Thus, PNs showed significant stereoselective inhibition of the specific binding of [3H](+)PN. On the other hand, [125I]omega-CgTX at concentrations of 0.075-0.6 nM showed scarcely any specific binding to these crude membranes, although at 0.6 nM it showed specific binding to crude membranes from rat brain in the same experimental conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Characteristics of 45Ca uptake stimulated by high KCl of differentiated and undifferentiated NG108-15 and PC12h cells

The characteristics of KCl-stimulated 45Ca uptake by neuroblastoma X glioma hybrid NG108-15 cells induced to differentiate with dibutyryl cAMP (Bt2cAMP) and of PC12h pheochromocytoma cells induced to differentiate with nerve growth factor (NGF) were studied. The extent and rate of KCl-stimulated 45Ca uptake by differentiated NG108-15 cells induced with Bt2cAMP were significantly higher than those of the undifferentiated cells. However, differentiation of PC12h cells induced with NGF did not enhance their extent or rate of KCl-stimulated 45Ca uptake. The effects of Ca agonist and antagonists indicated that the characteristics of KCl-stimulated 45Ca uptake by Bt2cAMP-treated NG108-15 cells and NGF-treated PC12h cells mainly reflected those of peripheral L-type voltage-sensitive calcium channels activated by high KCl. These results suggest that differentiated neural cells did not all show an enhanced capacity for KCl-stimulated 45Ca uptake, although the characteristic patterns of differentiation (extension of neurite-like processes, etc.) and that of effect by Ca agonist or antagonists on NG108-15 cells and PC12h cells were similar.

Acute renal failure and degenerative tubular lesions associated with in situ formation of adenovirus immune complexes in a patient with allogeneic bone marrow transplantation

We describe the development of acute renal failure and degenerative tubular lesions associated with local immune deposits in a patient with allogeneic bone marrow transplantation. A 21-year-old man with an acute myelocytic leukemia received a bone marrow graft from a cousin mismatched for a single HLA-DR locus antigen. Hemorrhagic cystitis due to adenovirus type 11 infection occurred 26 days after transplantation, and 17 days later the patients developed acute renal failure. A study of renal tissue obtained by needle biopsy showed degenerative and necrotic lesions, especially in the distal part of the nephron. By electron microscopy adenovirus type 11 particles were found in the nuclei of tubular cells and in cellular debris in tubular lumina. By immunofluorescence technique, granular immune deposits containing adenovirus type 11 related antigen(s), immunoglobulins, C3, and membrane attack complex (MAC) C5b-9 of the complement system were detected along the tubular basement membranes but not in glomeruli. The patient's IgG did not bind to normal human kidneys. These findings suggest that adenovirus type 11 directly induced acute tubular damage, and that the tubular immune deposits were formed "in situ" by viral antigens and circulating viral antibody.