Electro-optic Bdot probe measurement of magnetic fluctuations in plasma

We propose a combined use of a Pockels electro-optic sensor with a pickup loop coil (Bdot probe) for the measurement of magnetic fluctuations in plasmas. In this method, induced fluctuating voltage on the coil loop is converted into an optical signal by a compact electro-optic sensor in the vicinity of the measurement point and is transferred across optical fiber that is unaffected by electric noise or capacitive load issues. Compared with conventional Bdot probes, the electro-optic Bdot probe (1) is electrically isolated and free from noise pickup caused by the metallic transmission line and (2) can be operated at a higher-frequency range because of the smaller capacitance of the operation circuit, both of which are suitable for many plasma experiments. Conversely, the sensitivity of the current electro-optic Bdot probe arrangement is still significantly lower than that of conventional Bdot probes. A preliminary measurement result with the electro-optic Bdot probe showed the detection of a magnetic fluctuation signal around the cyclotron frequency range in the RT-1 magnetospheric plasma experiment.

Magnetospheric vortex formation: self-organized confinement of charged particles

A magnetospheric configuration gives rise to various peculiar plasma phenomena that pose conundrums to astrophysical studies; at the same time, innovative technologies may draw on the rich physics of magnetospheric plasmas. We have created a "laboratory magnetosphere" with a levitating superconducting ring magnet. Here we show that charged particles (electrons) self-organize a stable vortex, in which particles diffuse inward to steepen the density gradient. The rotating electron cloud is sustained for more than 300 s. Because of its simple geometry and self-organization, this system will have wide applications in confining single- and multispecies charged particles.

Association study between catechol-O-methyltransferase polymorphisms and uterine leiomyomas in a Japanese population

PURPOSE

To investigate a possible association between uterine leiomyomas and catechol-O-methyltransferase (COMT) polymorphisms in a Japanese population.

METHODS

We compared the allele frequencies and genotype distributions of the exon 4 NlaIII restriction site polymorphism (RSP), the P2 promoter HindIII RSP at -1217, and the exon 6 BglI RSP in the COMT gene in 250 leiomyoma cases and 182 controls using polymerase chain reaction-restriction fragment-length polymorphism analysis.

RESULTS

No significant differences in allele frequencies and genotype distributions of the exon 4 NlaIII RSP, the P2 promoter HindIII RSP at -1217, and the exon 6 BglI RSP were found between uterine leiomyoma cases and controls. Moreover, no associations were noted between these three polymorphisms in COMT genes and leiomyoma size or a family history of uterine leiomyomas.

CONCLUSION

COMT gene polymorphisms are unlikely to be associated with an increased risk of uterine leiomyomas in a Japanese population.

Effect of amino acids on the eutectic behavior of NaCl solutions studied by DSC

The effect of a series of amino acids on the eutectic behavior of NaCl solutions at isotonic concentration has been studied by differential scanning calorimetry. The inclusion of different amino acids had different effects on eutectic formation. The amino acids were grouped into four categories based on their effect on eutectic formation: category C were amino acids that had no effect on eutectic formation; category D amino acids inhibited eutectic formation; category T amino acids shifted the melting of the eutectic to a lower temperature; category E amino acids caused the formation of a new eutectic with a melting temperature approximately -5 degrees C. The mechanism of these different effects on eutectic behavior is discussed, based on the chemical structure of the amino acids.

Confinement of pure-electron plasmas in a toroidal magnetic-surface configuration

A pure-electron plasma has been confined in a toroidal magnetic-surface configuration for as long as classical diffusion time due to neutral collisions. By controlling the potential of the internal conductor, long-term stable confinement of electrons has been achieved in a toroidal geometry.

Injection of electron beam into a toroidal trap using chaotic orbits near magnetic null

Injection of charged particle beam into a toroidal magnetic trap enables a variety of interesting experiments on non-neutral plasmas. Stationary radial electric field has been produced in a toroidal geometry by injecting electrons continuously. When an electron gun is placed near an X point of magnetic separatrix, the electron beam spreads efficiently through chaotic orbits, and electrons distribute densely in the torus. The current returning back to the gun can be minimized less than 1% of the total emission.

Molecular cloning of novel mouse and human putative citrate lyase beta-subunit

Using a fluorescent differential display (FDD) technique, a novel cDNA was identified by screening for gene expressed differentially between the Dunn osteosarcoma cell line and the LM8 cell line, an isolated variant of the Dunn cell line that has high metastatic potential to the lung. Molecular cloning of the cDNA revealed the clone has similarity to a bacterial fermentation enzyme, the citrate lyase beta-subunit (CL-beta). Northern blot and competitive reverse transcription-PCR (RT-PCR) analysis revealed up-regulation of the gene in the LM8 cell line. An RNA Master blot indicated that the mRNA encoding CL-beta is expressed abundantly in murine heart, liver, and kidney. A human expressed sequence tag (EST) database search suggested that a similar cDNA is expressed in humans. A gene with identical sequence is located on chromosome 13 in the genome database (Sanger centre, UK). These data suggest that a citrate fermentation pathway may exist in eukaryotes including mammals.

The dorsiflexion-eversion test for diagnosis of tarsal tunnel syndrome

BACKGROUND

The clinical diagnosis of tarsal tunnel syndrome lacks objectivity and consistency. We have devised a new diagnostic physical examination test in which the tibial nerve is compressed as it runs beneath the flexor retinaculum behind the medial malleolus. In this test, the ankle is passively maximally everted and dorsiflexed while all of the metatarsophalangeal joints are maximally dorsiflexed and held in this position for five to ten seconds.

METHODS

We performed this test on fifty normal volunteers (100 feet) and on thirty-seven patients (forty-four feet) treated operatively for tarsal tunnel syndrome between 1987 and 1997. We performed the maneuver both preoperatively and postoperatively and recorded any consequent changes in the signs and symptoms; during the operation we observed the altered anatomical relationships in the tarsal tunnel that were produced by the maneuver. The average duration of follow-up was three years and eleven months.

RESULTS

Before the operation, the signs and symptoms of tarsal tunnel syndrome were intensified or induced by the maneuver in fifteen of the twenty feet of the patients who reported numbness, in fifteen of the seventeen feet of those who reported pain alone, and in six of the seven feet of those who had combined numbness and pain. Local tenderness was intensified in forty-two of forty-three feet, and it was induced in one foot in which it had been previously absent. A Tinel sign became more pronounced in forty-one feet, and the sign was induced in three feet in which it had been absent previously. During the operation, the tibial nerve was stretched and compressed beneath the laciniate ligament when the ankle was dorsiflexed, the heel was everted, and the toes were dorsiflexed. Preoperative signs and symptoms disappeared on an average of 2.9 months after the operation, and they could not be induced by repeating the test except in three patients, all of whom had tarsal tunnel syndrome subsequent to a fracture of the calcaneus. In the normal volunteers, no symptoms or signs could be induced by the test.

CONCLUSION

This new physical examination test is effective in facilitating the diagnosis of tarsal tunnel syndrome.

Effects of hydrogen peroxide on the transient outward current in rabbit atrial myocytes

1. In the present study, we investigated the effects of hydrogen peroxide (H2O2) on the 4-aminopyridine-sensitive transient outward current (I(TO)) in rabbit atrial myocytes using the amphotericin B-perforated patch voltage-clamp method. 2. Superfusion of myocytes with H2O2 at 100 micromol/L gradually slowed the time-course of inactivation of I(TO) and increased the peak by 9% (n = 9). The H2O2-induced slowing of I(TO) inactivation was concentration dependent (over the concentration range 10 micromol/L to 1 mmol/L). These effects were hardly reversed by washout of H2O2, but were quickly abolished by dithiothreitol (2 mmol/L). 3. Bisindolylmaleimide (100 nmol/L), an inhibitor of protein kinase C, significantly attenuated the H2O2-induced effects on I(TO). 4. These results suggest that rabbit atrial I(TO) is susceptible to oxidation by H2O2 at concentrations relevant to those encountered during ischaemia/reperfusion and that protein kinase C modulates the effects of H2O2.

Surgical treatment for hallux valgus with painful plantar callosities

We retrospectively reviewed the results of a distal soft-tissue procedure and proximal crescentic osteotomy of the first metatarsal combined with a proximal shortening osteotomy of the second and/or third metatarsal. This was in patients who had hallux valgus with painful plantar callosities. The review covered seven years of procedures (1989-1996) in 12 patients (14 feet) averaging 53 years of age. Average follow-up was 52 months. All patients had pain at the first metatarsophalangeal joint and had metatarsalgia preoperatively. At follow-up, 11 feet had no pain at the first metatarsophalangeal joint, and three had some improvement of pain. Ten feet had no metatarsalgia, two had improvement of metatarsalgia, and two feet had transfer lesions postoperatively and required reoperation. The angle of hallux valgus averaged 40 degrees preoperatively and 13 degrees postoperatively. The intermetatarsal angle averaged 18 degrees preoperatively and 6 degrees postoperatively. Mean decreases in length of the second and third metatarsal after surgery were 5.4 mm and 4.8 mm, respectively. Our results suggested that this combined procedure for hallux valgus with painful plantar callosities may be successful, in carefully selected patients.

Bax induction activates apoptotic cascade via mitochondrial cytochrome c release and Bax overexpression enhances apoptosis induced by chemotherapeutic agents in DLD-1 colon cancer cells

Cancer cells express different levels of apoptosis-promoting Bax protein. The present study evaluated whether induction of Bax initiates apoptosis and whether Bax overexpression enhances apoptosis induced by several chemotherapeutic agents in DLD-1 colon cancer cells, which originally express a high level of endogenous Bax protein and a low level of Bcl-2 protein. To investigate these two points, parental DLD-1 cells were transfected with the Tet-On Bax induction system (pTet-On and pTRE-Bax plasmids), and stable transduced cells were obtained. Induction of Bax by the Tet-On system initiated cytochrome c release from mitochondria, caspase-3 activation, and apoptosis to some extent in DLD-1 cells. Apoptosis induced by a chemotherapeutic agent, 5-fluorouracil, mitomycin C, paclitaxel, doxorubicin, or cisplatin, was enhanced by Bax overexpression. These findings suggest that Bax-overexpression-based gene therapy combined with chemotherapy would be effective in the treatment of colon cancer.

Distal soft tissue procedure and proximal metatarsal osteotomy in hallux valgus

The results of a distal soft tissue procedure and a proximal metatarsal osteotomy in patients with symptomatic hallux valgus deformity were reviewed. The series consisted of 33 patients (47 feet; mean age of patients, 44 years). The average followup period was 48 months. At followup, 41 feet (29 patients, 85%) were free from pain at the first metatarsophalangeal joint. In six feet (four patients), the pain was improved but persisted. The mean hallux valgus angle was 38 degrees before surgery and 13.8 degrees after surgery. The mean intermetatarsal angle was 17.7 degrees before surgery and 7 degrees after surgery. The postoperative hallux valgus angle and intermetatarsal angle in patients who had pain at the first metatarsophalangeal joint after surgery were greater than those in patients without pain after surgery. This procedure corrects the hallux valgus deformity and relieves the symptoms, but careful attention should be paid to the surgical technique to obtain consistent and satisfactory results.

Reconstruction for chronic lateral ankle instability using the palmaris longus tendon: is reconstruction of the calcaneofibular ligament necessary?

The palmaris longus tendon was used to reconstruct the anterior talofibular ligament (ATFL) in 27 ankles with chronic lateral instability. The mean age of the patients at surgery was 23 years, and the follow-up was more than 2 years. The functional evaluation showed excellent or good results in all ankles. Twenty-seven ankles were divided into two groups according to operative findings: group A consisted of 11 ankles with old isolated injury of the ATFL, and group B consisted of 16 ankles with old combined injuries of the ATFL and the calcaneofibular ligament. There were no significant differences in clinical results between group A and group B. The preoperative mean talar tilt angles on stress radiograph in group B were significantly larger than those in group A. At follow-up, there were no significant differences in the mean talar tilt angles between group A and group B. We demonstrate that reconstruction of the calcaneofibular ligament along with the ATFL is not necessary for patients with chronic combined lateral ligament instability.

EP receptor-mediated inhibition by prostaglandin E(1) of cardiac L-type Ca(2+) current of rabbits

Prostaglandin E(1) (PGE(1)) has cardioprotective effects on the ischemic-reperfused heart. To clarify the mechanisms underlying the protective action of PGE(1) on myocardium, we examined the effect of PGE(1) on the L-type Ca(2+) current (I(Ca)) using single atrial cells from rabbits. PGE(1) did not show a significant effect on basal I(Ca) but inhibited the I(Ca) prestimulated by isoproterenol (Iso, 30 nM). This inhibition was concentration dependent (EC(50) = 0.027 microM). Both sulprostone, a specific PGE receptor subtype (EP(1) and EP(3)) agonist, and 11-deoxy-PGE(1), an EP(3) agonist, inhibited the Iso-stimulated I(Ca), similar to PGE(1). Pretreatment with pertussis toxin (PTX) abolished the PGE(1) inhibition of I(Ca). Both the application of forskolin plus IBMX and intracellular dialysis with 8-bromoadenosine 3',5'-cyclic monophosphate eliminated the effect of PGE(1). PGE(1) did not show any further inhibition of I(Ca) when the effect of Iso was almost fully antagonized by acetylcholine. Methylene blue (guanylate cyclase inhibitor), KT-5823 (cGMP-dependent protein kinase inhibitor), and erythro-9-(2-hydroxy-3-nonyl)adenine (type II phosphodiesterase inhibitor) did not significantly change the inhibitory effect of PGE(1). These findings suggest that 1) PGE(1) inhibits Iso-stimulated I(Ca) by binding to the EP(3) receptor and 2) the PTX-sensitive and cAMP-dependent pathway is involved in the PGE(1) inhibition of I(Ca), but the nitric oxide-cGMP-dependent pathway is not. The PGE(1)-induced antiadrenergic effect shown in this study may contribute to the PGE(1) protection of myocardium against ischemia.

Tyrosine kinase-dependent modulation by interferon-alpha of the ATP-sensitive K+ current in rabbit ventricular myocytes

We examined the effects of interferon-alpha on the ATP-sensitive K+ current (IK,ATP) in rabbit ventricular cells using the patch-clamp technique. IK,ATP was induced by NaCN. Whole-cell experiments indicated that interferon-alpha (5 x 10(2) - 2.4 x 10(4) U/ml) inhibited IK,ATP in a concentration-dependent manner (60.7+/-7.5% with 2.4 x 10(4) U/ml). In cell-attached configuration, interferon-alpha (2.4 x 10(4) U/ml) applied to the external solution also inhibited the activity of the single ATP-sensitive K+ (KATP) channel by 56.0+/-5.8% without affecting the single channel conductance. The inhibitory effect of IK,ATP by interferon-alpha was blocked by genistein and herbimycin A, tyrosine kinase inhibitors, but was not affected by N-(2-metylpiperazyl)-5-isoquinolinesulfoamide (H-7), an inhibitor of protein kinase C and cAMP-dependent protein kinase. These findings suggest that interferon-alpha inhibits the cardiac KATP channel through the activation of tyrosine kinase. The tyrosine kinase-mediated inhibition of IK,ATP by cytokines may aggravate cell damage during myocardial ischemia.

P2 purinoceptors contribute to ATP-induced inhibition of L-type Ca2+ current in rabbit atrial myocytes

OBJECTIVE

Adenine compounds, including adenosine-5'-triphosphate (ATP) and adenosine (Ado), exert inhibitory effects on myocardium via P1 (subtype A1) purinoceptors. However, ATP per se is a potent activator of P2 purinoceptors. Our aim was to elucidate the respective roles of P1 and P2 purinoceptors in the actions of ATP on L-type calcium current (ICa) in rabbit atrial cells.

METHODS AND RESULTS

A whole cell clamp technique was used to record ICa in single atrial cells from the rabbit heart. ATP (0.1 mumol/1-3 mmol/l) produced an inhibitory effect on ICa prestimulated by isoproterenol (ISO, 30 nmol/l), even in the presence of Ado (1 mmol/l). Both 1,3-dipropyl-8-cyclopentylxanthine (A1 blocker) and suramin (P2 blocker) partially blocked the ATP-induced inhibition of ICa, while their co-application nearly completely abolished the effect of ATP. ATP-gamma S (30 mumol/l) inhibited ISO-stimulated ICa significantly, and this inhibition was completely blocked by suramin. alpha, beta-Methylene-ADP, an inhibitor of hydrolysis of AMP to Ado, eliminated the suramin-resistant component of ICa inhibition by ATP. Pretreatment with pertussis toxin (PTX) abolished the ATP inhibition of ICa. Both intracellular dialysis with 8Br cAMP and the application of forskolin plus 3-isobutyl-1-methylxanthine also eliminated the effect of ATP.

CONCLUSIONS

Both P1 and P2 purinoceptors are involved in the ATP inhibition of ISO-stimulated ICa in rabbit atrial cells. The P1 stimulation by ATP results from hydrolysis of ATP to Ado. Both the P2- and the P1-mediated effects of ATP and Ado, respectively. involve a PTX-sensitive and cAMP-dependent pathway.

Blockage by terfenadine of the adenosine triphosphate (ATP)-sensitive K+ current in rabbit ventricular myocytes

We examined the blocking effects of terfenadine, an antihistaminic agent, on the ATP-sensitive K+ current (IK,ATP) in rabbit ventricular cells. IK,ATP was induced by cromakalim or NaCN. Terfenadine blocked the IK,ATP with an IC50 of 1.7 microM at -10 mV. This blockage was voltage dependent; depolarization induced a stronger blockage. According to the transmembrane electrical field model, terfenadine interacts with the site located 15 to 18% from the cytoplasmic membrane surface. In line with the assumption that the binding site is near the cytoplasmic surface, terfenadine applied to the cytoplasmic solution potently inhibited the single-channel activity for IK,ATP in the inside-out configuration (IC50 0.19 microM). In contrast, terfenadine applied to the external solution did not affect the channel activity in the cell-attached configuration, but inhibited it when applied into the pipette. The inhibition of the single channels by terfenadine was accompanied by flickering of the channels. These findings suggest that 1) terfenadine blocks the ATP-sensitive K+ channel in the open state, 2) the binding site is near the internal membrane surface and 3) terfenadine is poorly diffusible into the lipid biomembrane and accesses the binding site via the hydrophilic pathway. Terfenadine also inhibited the transient outward K+ current, inward rectifier K+ current and E4031-sensitive rectifier K+ current. However, the inhibition of these repolarization currents by terfenadine at 1 microM was not sufficient to prolong the action potential duration significantly. Whereas, terfenadine (1 microM) prolonged the action potential duration which had been shortened by cromakalim. Terfenadine may modify the ischemia-induced arrhythmias by blocking IK,ATP.

Purification of recombinant human pepsinogens and their application as immunoassay standards

Human pepsinogen (PG) A and C were cloned in Escherichia coli, but the levels of expression were low and unstable. When there were fused to maltose-binding protein (MBP), the fusion proteins (MBP-PGA and MBP-PGC) were expressed as the major products. Although these fused products were almost totally recovered from the insoluble fraction, the renaturation and purification procedures were easy and simple. MBP-PGA and the PGA segment obtained by factor Xa digestion (designated as r-PGA) possessed proteolytic activities equivalent to native PGA purified from gastric tissue (t-PGA). For PGCs (MBP-PGC, r-PGC and t-PGC) also, the specific activities were almost the same. However, the activities of PGCs were about 3- to 4-hold higher than those of PGAs. In PGA and PGC immunoassay systems, r-PGs (r-PGA and r-PGC) and the EIA kit standard PGs (gastric mucosal PGs) exhibited a good correlation. From these results, r-PGs would seem to be applicable as assay standards without compromising the sensitivity of the immunoassay systems.

Osteochondral lesions of the proximal phalanx of the great toe: a report of two cases

Two cases of osteochondral lesions of the proximal phalanx of the great toe at the interphalangeal joint are presented. This condition is characterized by pain, swelling, and tenderness at the interphalangeal joint. The roentgenographic characteristics resemble osteochondritis dissecans. Curettage and bone grafting to the lesion is effective. These conditions in adolescent soccer players may be caused by chronic repetitive overloading of the interphalangeal joint using soccer shoes with soft, supple, and narrow toe boxes.

Dopamine stimulation of cardiac beta-adrenoceptors: the involvement of sympathetic amine transporters and the effect of SKF38393

1. Mechanisms underlying beta-adrenoceptor stimulation by dopamine were examined on guinea-pig Langendorff-perfused hearts and isolated cells from the right atrium, by using the chronotropic effects and the enhancement of L-type Ca2+ current (ICa,L) in the presence of prazosin as indicators of beta-adrenoceptor stimulation. Dopamine-induced overflow of noradrenaline (NA) concentrations was measured by high-performance liquid chromatography. 2. Dopamine caused positive chronotropic effects with an EC50 of 2.5 microM and induced NA overflow with a similar EC50 (1.3 microM). The chronotropic effect of dopamine was abolished by bisoprolol (1 microM). 3. The effects of dopamine were maintained during prolonged application, whereas the effects of tyramine faded with time. Dopamine (3 microM) restored the chronotropic effects and the NA release suppressed by pretreatment with tyramine, suggesting a de novo synthesis of NA during the exposure to dopamine. 4. Dopamine (3 microM)-induced NA release was not affected by tetrodotoxin, omega-conotoxin, rauwolscine, ICI118551 or sulpiride, but was inhibited by desipramine, a NA uptake inhibitor (IC50 approximately 1 microM). It was also not affected by GBR12909 and bupropion, dopamine uptake inhibitors in the central nervous system. 5. SKF38393, a D1 receptor partial agonist, potently inhibited the 3 microM dopamine-induced release of NA (IC50 approximately 0.1 microM). D1 receptors are not involved in the DA-induced release of NA, since SCH23390 (3 microM), a potent D1 antagonist, inhibited the NA release only slightly, and dihydrexidine (1 microM) and chloro-APB (1 microM), full D1 agonists, caused no significant NA release. 6. SKF38393 inhibited tyramine-induced overflow of NA, and potentiated the field stimulation-induced NA release. SKF38393 and desipramine retarded the decay of the stimulation-induced tachycardia in a similar manner. These results indicate that SKF38393 is a potent monoamine transport inhibitor and a useful tool for the functional evaluation of indirectly-acting sympathomimetic agonists in the heart. In the presence of SKF38393 (10 microM), dopamine at 1 microM showed no chronotropic effect. 7. Voltage clamp experiments with isolated atrial cells revealed that dopamine is a weak partial agonist. The EC50 for ICa,L stimulation by dopamine was high (13 microM). As a result, dopamine at 1 microM did not affect ICa,L. Bisoprolol abolished the stimulation of ICa,L by dopamine (30 microM), and dihydrexidine (1 microM) did not affect ICa,L. 8. It was concluded that the cardiac effects of dopamine at clinically relevant concentrations (< 1 microM) result almost exclusively from the indirect effect of beta adrenoceptor stimulation, involving the release of NA from sympathetic nerve terminals. The roles of the direct stimulation of beta adrenoceptors by dopamine at these concentrations and the stimulation of postjunctional D1 receptors seem negligible. The desipramine- and SKF38393-sensitive monoamine transporter mediates the release of NA.

Muscarinic inhibition of basal L-type calcium current in pacemaker cells from the rabbit atrioventricular node

Effects of acetylcholine (ACh) on the L-type calcium current were examined in isolated atrioventricular nodal cells that exhibited spontaneous contractions. ACh (0.1 to 10 microM) inhibited basal calcium current dose-dependently. This inhibition was eliminated by dialysis with 8Br cAMP or cAMP-dependent kinase inhibitory peptide. Both extracellular N-ethylmaleimide 50 microM and intracellular GDPssS 0.2 mM abolished the ACh effect. Dialysis with cGMP or NG-monomethyl-L-arginine did not significantly affect ACh inhibition of basal calcium current. Similarly, cGMP-dependent protein kinase inhibitor KT5823 (1 microM) and the type II phosphodiesterase inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine (30 microM) did not attenuate the ACh effect. Therefore, ACh inhibits the basal calcium current in the atrioventricular node mainly by suppressing cAMP synthesis through the inhibitory GTP-binding protein.

Negative chronotropic actions of endothelin-1 on rabbit sinoatrial node pacemaker cells

1. The effects of endothelin-1 (ET-1) on sinoatrial (SA) node preparations of the rabbit heart were studied by means of whole-cell clamp techniques. 2. ET-1 at 1 nM slowed the spontaneous beating activity and rendered half of the cells quiescent. At a higher concentration of 10 nM, the slowing and cessation of spontaneous activity were accompanied by hyperpolarization. 3. In voltage-clamp experiments, ET-1 decreased the basal L-type Ca2+ current (Ica(L)) dose-dependently with a half-maximal inhibitory concentration (EC50) of 0.42 nM and maximal inhibitory response (Emax) of 49.5%. The delayed rectifying K+ current (Ik) was also reduced by 33.2 +/- 11.1% at 1 nM. In addition an inwardly rectifying K+ current was activated by ET-1 at higher concentrations (EC50 = 4.8 nM). These ET-1-induced changes in membrane currents were abolished by BQ485 (0.3 microM), a highly selective ETA receptor antagonist. 4. When Ica(L) was inhibited by ET-1 (1 nM), subsequent application of 10 microM ACh showed no additional decrease in Ica(L), suggesting the involvement of cyclic AMP in the effects of ET-1 on Ica(L). In contrast, 1 nM ET-1 further decreased Ica(L) in the presence of 10 microM ACh, suggesting that ET-1 activates some additional mechanism(s) which inhibit Ica(L). The ET-1-induced Ica(L) inhibition was abolished by protein kinase A inhibitory peptide (PKI, 20 microM) or H-89 (5 microM). However, the Ica(L) inhibition was not affected by methylene blue (10 microM), suggesting a minor role for cyclic GMP in the effect of ET-1 under basal conditions. 5. ET-1 failed to inhibit Ica(L) when the pipette contained GDP beta S (200 microM). However, incubation of the 21.5 +/- 9.5%, whereas it abolished the inhibitory effect of ACh on Ica(L). 6. Intracellular perfusion of 8-bromo cyclicAMP (8-Br cyclicAMP, 500 microM) attenuated, but did not abolish the inhibitory effect of ET-1 on Ica(L). This 8-Br cyclicAMP-resistant component (17.5 +/- 14.4%, n = 20) was not affected by combined application of 8-Br cyclicAMP-bromo cyclicGMP (500 microM), ryanodine (1 microM) or phorbol-12-myristate-13-acetate (TPA; 50 nM). 7. In summary, ET-1 exerts negative chronotropic effects on the SA node via ETA-receptors. ET-1 inhibits both ICa(L) and Ik, and increases background K+ current. The inhibition of ICa(L) by ET-1 is mainly due to reduction of the cyclicAMP levels via PTX-sensitive G protein, but some other mechanism(s) also seems to be operative.

Preferential cytotoxicity to tumor cells of 3,5-diprenyl-4-hydroxycinnamic acid (artepillin C) isolated from propolis

A tumoricidal substance was isolated from Brazilian propolis as guided by cytotoxicity assay on HuH 13 (human hepatocellular carcinoma) cell and was characterized to be 3-[4-hydroxy-3,5-bis (3-methyl-2-butenyl) phenyl]-2-propenoic acid (3,5-diprenyl-4-hydroxycinnamic acid (artepillin C)). It exhibited preferential cytotoxicity to tumor cells cultured in vitro. The cytotoxicity observed seemed to be partly attributable to apoptosis-like DNA fragmentation. The compound showed anti-tumor activity more effective than that of 5-fluorouracil to transplantable human tumor cell lines when tested on histoculture drug response assay system.

Isolation and characterization of cytotoxic diterpenoid isomers from propolis

The methanol extract of Brazilian propolis was fractionated by HPLC, based on HuH13 (human hepatocellular carcinoma) cell cytotoxicity assay. Two isomers of diterpenoid with a molecular formula of C20H30O3 (MW: 318.46) were isolated. The structures of these colorless compounds were determined as clerodane diterpenoids (I, 15-oxo-3, 13Z-kolavadien-17-oic acid; II, 15-oxo-3Z, 13E-kolavadien-17-oic acid).

Single coronary artery with infundibular pulmonary stenosis

Images

Biochemical and immunochemical properties of modified human neuron-specific enolase

125I-Labeled recombinant human neuron-specific enolase (R-NSE) was inadequate for RIA as a labeled antigen. The binding activity of labeled R-NSE to the antibody was markedly decreased. To supplement this defect and facilitate purification, we constructed two R-NSE derivatives, Y-NSE (one tyrosine residue was added at the N-terminal of R-NSE) and Y-NSE.H6 (six histidine residues were further added at the C-terminal of Y-NSE). The biochemical and immunochemical characteristics of these R-NSE derivatives were essentially the same to those of R-NSE. These derivatives were useful not only as standards for enzyme immunoassay (EIA), but also as labeled antigens for RIA. These results clearly indicate that the reactivity of these modified NSEs to anti-NSE antibody is almost equivalent to that of human brain gammagamma-enolase (B-NSE), and that even if the modified NSEs are labeled, they retain their binding affinities to antibodies in contrast to R-NSE.

Delineation of premature P waves on four-dimensional electrocardiography, a new display of electrical forces by computer techniques

This study investigated the feasibility of four-dimensional electrocardiography (4-D ECG), a new display in which the vector loop was rotated and scanned along a timed axis to overcome the shortcomings of vectorcardiography (VCG). The subjects consisted of 38 patients with premature atrial complexes and 30 controls. The orthogonal Frank electrocardiograms were rotated three-dimensionally according to the right-hand rectangular coordinate system and scanned along a timed axis. The P wave delineation score, signifying good agreement with the intraobserver and interobserver variability, was significantly higher in 4-D ECG than those in the orthogonal leads or those on the transverse and frontal projections (P < 0.001). The authors measured the premature P loop areas as viewed from 361 directions. P loop areas were best delineated when viewed from cranial directions of 42.6 +/- 34.0 degrees and from rightward directions of 11.3 +/- 30.7 degrees. Adequate cranial rotation followed by scanning along a timed axis will maximally delineate premature atrial signals and provide comprehensive visualization of electrical forces.

Modulation of L-type Ca current by denopamine, a nonparenteral partial beta 1 stimulant, in rabbit ventricular cells

The effects of denopamine, a nonparenteral partial beta agonist which is used clinically in Japan, on the L-type Ca2+ current (ICa) were examined in rabbit ventricular cells. Denopamine stimulated basal ICa with a maximum response of +33.2% and a concentration for half-maximal response (EC50) of 0.039 microM. The maximum response of ICa was only a quarter of that induced by isoprenaline (ISO), while 10 microM denopamine elicited 70-75% of the maximum inotropic response in the papillary muscle preparations. The denopamine stimulation of ICa was abolished by selective beta 1 antagonists (atenolol or bisoprolol). Pretreatment with forskolin or dialysis with cAMP also abolished the stimulation. Denopamine, in turn, inhibited ISO-stimulated ICa. This inhibition was not affected by pretreatment with pertussis toxin or prazosin. The presence of denopamine at various concentrations caused a rightward shift in the concentration/response curve for ISO stimulation of ICa. The Schild plot for this effect had a slope of 0.99 and Kp of 0.20 microM. In the presence of guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S) (0.5 mM) in the pipette, denopamine (10 microM) stimulated the ICa to 86 +/- 5% of the maximum response induced by ISO. These findings indicate that denopamine modulates ICa exclusively through the beta 1 adrenoceptor-adenylate cyclase pathway, that the stimulatory GTP-binding protein regulates the agonistic potency of denopamine, and that the signal from the beta 1 adrenoceptors is amplified between ICa and the tension development, which would contribute to the spare capacity of beta adrenoceptors.

Purification of pepsinogens from human urine and electrophoretic analysis by caseogram print

Pepsinogen (PG) A and C were purified from human urine, and analyzed by a highly sensitive detection method, "caseogram print". Purification was achieved by a series of conventional chromatographies and FPLC. A relatively large amount (13.2 mg) of PGA was purified from about 20 liters of urine. Purified PGA was separated by a Mono-Q column into each of its isozymogens. The elution order (PGA-5, 4+3, 2) corresponded to the order of electrophoretic migration. Although the concentration of urinary PGC was very low, a trace amount was purified and visualized by electrophoresis. The urinary and mucosal PGCs migrated at the same position, and urinary PGC was detected as two isozymogens similarly to mucosal PGC, suggesting that urinary and mucosal PGCs may be essentially identical.

Modification of human neuron-specific enolase for application to radioimmunoassay

A recombinant human neuron-specific enolase (R-NSE), isolated from Escherichia coli, could not be used in an RIA system because of instability upon labeling. To apply R-NSE to RIA and to simplify the purification procedure, the N- and C-terminals of R-NSE were modified by tyrosine- and histidine-tagging, respectively. SY-NSE, containing one additional tyrosine residue, was obtained from both soluble and insoluble fractions. More derivatives tagged by two or four tyrosine residues were expressed, but only in the insoluble fraction. SY-NSE and SY-NSE.H6 (containing six histidine residues at C-terminal of SY-NSE) purified from the soluble fraction were applicable to the RIA system, indicating that the addition of a tyrosine residue at the terminal is effective if the antigen is unstable during labeling.

Decreased sensitivity to beta-adrenergic stimulation of the ventricular cells isolated from the spontaneously hypertensive rat heart

1. The stimulatory effects of isoproterenol on the L-type Ca2+ current (ICa) were compared between the control (WKY) and hypertensive (SHR) rat heart cells, using the patch-clamp method. 2. The current density and the shape of the current-voltage relationship for ICa were not different between the two groups. However, the maximal percentage increase in response to isoproterenol was smaller in SHR (+91% in SHR and +81% in WKY), and the ED50 was significantly higher in SHR (0.081 mu mol/L in SHR and 0.020 mu mol/L in WKY). IBMX, a potent phosphodiesterase inhibitor, significantly increased the isoproterenol-stimulated ICa in SHR, but not in WKY. These results suggest an impaired cAMP production in SHR heart cells.

Conversion of cathepsin E to enzymatic unstable form in gastric cancer cells

A new acid proteinase in human gastric cancer, named medium moving proteinase (Med.P), was found also in a gastric cancer transplanted into nude mouse. However, Med.P disappeared when the samples prepared from gastric cancer tissues were left for over 4 weeks at -80 degrees C, whereas the activity of cathepsin E (CE) increased. When these samples were reduced by dithiothreitol (DTT), Med.P appeared again and the CE activity decreased. These phenomena, revealed by electrophoretic analyses, indicated that Med.P is a monomeric form of CE (mono-CE). At weakly alkaline pH and after heating, mono-CE appeared to be more unstable than CE. These results indicated that CE assume an enzymatically unstable monomeric form in cancer cells.

Does dopamine act on myocardial cells?

We examined the electrophysiological effects of dopamine on the single myocardial cells isolated from the rat and rabbit heart. Dopamine at a concentration of 1 or 10 microM did not affect the L-type Ca2+ current (ICa) or the transient outward current (ITO) in rat ventricular, rabbit atrial, ventricular, and sinoatrial node cells. It did not induce any detectable change in the action potential configuration of the rabbit ventricular cells either. We conclude that dopamine does not directly act on myocardial cells at least in terms of the electrophysiological properties.

Electrophysiological effects of changrolin, an anti-arrhythmic agent derived from Dichroa febrifuga, on guinea-pig and rabbit heart cells

1. The electrophysiological effects of changrolin (CRL), a Chinese anti-arrhythmic drug derived from a traditional antimalarial plant, were examined using the whole-cell patch-clamp method on single cells isolated from guinea-pig and rabbit hearts. 2. At a clinically relevant concentration of 50 mumol/L changrolin inhibited ICa by 19.3 +/- 6.0% and 17.3 +/- 2.6% in guinea-pig and rabbit ventricular cells, respectively. The voltage-dependent channel availability curve was not affected. The CRL effect was enhanced to a small extent during a repetitive stimulation at 2 Hz. 3. INa was resistant to CRL and the channel availability curve was also unaffected. A small use-dependent inhibition was observed only when the INa was elicited at 5 Hz in the presence of 300 mumol/L CRL. 4. At 50 mumol/L, CRL did not affect the time-independent inward rectifier and the delayed rectifier K+ currents (IK1 and IK, respectively), but inhibited the transient outward current (ITO) by 17.7 +/- 2.4%. Changrolin significantly shortened the action potential duration in both guinea-pig and rabbit ventricular cells. 5. In conclusion, CRL inhibits ICa and ITO but has little effect on INa.

Angiotensin II inhibition of L-type Ca2+ current in sinoatrial node cells of rabbits

The actions of angiotensin II (ANG II) were examined in the spontaneously active cells isolated from the rabbit sinoatrial node, using the nystatin-permeabilized, whole cell, patch-clamp method. At 30 nM, ANG II significantly lowered the spontaneous firing rate of the action potentials from 212 +/- 21 to 172 +/- 32 beats/min, with a concomitant reduction in the action potential amplitude. The voltage-clamp experiments showed that ANG II inhibited the L-type Ca2+ current (ICa) with a dissociation constant (Kd) of approximately 4 nM and a maximal inhibition of 30%. The inhibition was blocked by an AT1-receptor antagonist CV11974. Acetylcholine (ACh) at 10 microM reduced the ICa by 42 +/- 12%, and ANG II did not cause any further inhibition in the presence of ACh. At 100 nM, ANG II reduced the ICa by only 12% in the presence of 2 microM isoproterenol, and a similar inhibition was observed with 0.1 microM ACh. ANG II did not affect the dibutyryl adenosine 3',5'-cyclic monophosphate-stimulated ICa. Protein kinase C activator 12-O-tetra-decanoylphorbol-13-acetate did not mimic ANG II in the effects on ICa, and preincubation of the cells with calphostin C, a protein kinase C inhibitor, did not attenuate the ANG II effect. ANG II exerts a negative chronotropic effect in the pacemaker cells as its direct action through a pathway involving adenosine 3',5'-cyclic monophosphate-dependent protein kinase.

Ethanol inhibition of Ca2+ and Na+ currents in the guinea-pig heart

The effects of ethanol on L-type Ca2+ and fast Na+ currents (ICa and INa, respectively) were examined using the whole-cell patch-clamp experiments on guinea-pig ventricular cells. At a clinically relevant concentration of 24 mM, ethanol slightly but significantly shortened the action potential duration, and reduced the ICa by 7 +/- 4% (mean +/- S.D.). This concentration of ethanol did not affect INa, but a lethal concentration of ethanol (80 mM) significantly inhibited INa by 13 +/- 5%. The voltage dependence of INa activation was not affected by ethanol, whereas the inhibitions of ICa by 80 mM ethanol and INa by 240 mM were both accompanied by a several mV shift in the channel availability curve toward more negative potentials, suggesting that the channels in the inactivated state are more susceptible to ethanol. The ICa inhibition by ethanol at clinically relevant concentrations could contribute to a negative inotropic effect, action potential shortening and development of arrhythmias, while the pathophysiological significance of ethanol inhibition of INa seems less important.

Electrophoretic analysis of a gastric cancer-associated acid proteinase using a highly sensitive detection system

A highly sensitive detection system for acid proteinase separated on polyacrylamide gel was established. This system consisted of two-dimensional electrophoresis, combined with isoelectric focusing and polyacrylamide gel electrophoresis, and casein clotting (caseogram). Human urine, serum and gastric tissues obtained from normal individuals and gastric cancer patients were analyzed using this system. The previous electrophoretic method was not sufficiently sensitive to detected small amounts of pepsinogen (PG) C in normal urine. However, the new rapid and sensitive method clearly revealed its presence. In gastric tissue containing cancer cells, an additional proteinase, which was not present in normal tissue, was detected and named medium moving proteinase (MMP). MMP resembled PGs in alkaline stability rather than the non-PG proteinase, slow moving proteinase (SMP).

Modulation of sodium current by lactate in guinea pig ventricular myocytes

OBJECTIVE

The aim was to elucidate whether or not lactate modifies the fast sodium current (INa) in cardiac cells.

METHODS

A tight seal whole cell clamp technique was used to record the action potentials and INa in single ventricular cells from the guinea pig heart.

RESULTS

In voltage clamp experiments, superfusion with 20 mM lactate shifted both the normalised conductance (gNa)-voltage relationship and the channel availability curve toward hyperpolarisation by approximately 4 mV, but did not affect the maximum conductance (gNa,max). In the test solution containing only CaCl2 as the main divalent component, 20 mM lactate reduced the ionised calcium concentration from 1.02 to 0.84 mM. When the calcium concentration was kept constant by the addition of CaCl2 into the lactate containing solution the lactate effect was nullified. However, a change in the calcium concentration from 1.0 to 0.84 mM without lactate induced a 4 mV negative shift of the channel availability curve. Current clamp experiments in Tyrode solution showed that 20 mM lactate shifted the threshold for the action potential upstroke by 2.5-3 mV, in accordance with the voltage clamp experiments.

CONCLUSIONS

Lactate modifies INa of ventricular myocytes by shifting its kinetics toward hyperpolarisation. This shift seems to be caused exclusively by a decrease in the ionised divalent cation concentrations and a resultant change in the negative surface charge of the sarcolemma.

A case of lipoprotein glomerulopathy successfully treated with probucol

A 54-year-old woman presented proteinuria and severe hyperlipoproteinemia, She had type III hyperlipoproteinemia with the phenotype E2/2. Renal biopsy specimen revealed lipoprotein thrombi within the glomerular capillary lumina without tubulointerstitial lesion and deposition of IgA in the mesangium and peripheral capillary loops, indicating lipoprotein glomerulopathy with IgA nephropathy. Treatment with probucol resulted in the improvement of both hyperlipoproteinemia and proteinuria with the disappearance of the lipoprotein thrombi in the glomerular capillary without any change in the mesangial IgA deposition. The data suggest that probucol may be effective against the early stage of lipoprotein glomerulopathy with less lipoprotein thrombi and without tubulointerstitial damage.