Cardiac channel gating charge movements: recovery from inactivation

The nonlinear charge movements which occur during membrane depolarization of cardiac ventricular myocytes (QON) have been previously identified and separated, by kinetic and steady-state criteria, into constituent components arising from the gating of Na channels and Ca channels. In contrast, the nature and time course of the OFF charge movements (QOFF), which follow membrane repolarization have not been as clearly established. In order to address this question cardiac QOFF was studied using small-diameter, 17-day-old embryonic chick ventricular myocytes that can be rapidly and uniformly voltage-clamped. The application of brief (5.4 ms) depolarizing steps were employed to produce Na channel inactivation but little Ca channel inactivation. Following the return of the membrane potential to -100 mV QOFF, measured as the gating current termed IgOFF, displayed two kinetic components. Double exponential fits to IgOFF yielded time constants of a few tenths of a millisecond for the fast component (IgOFFfast) and of 1-2 ms for the slower component (IgOFFslow). The time course and voltage dependence for the slower component suggested that it might be linked to the inactivation, and the recovery from inactivation, of Na channels. In order to identify these kinetic components double-pulse protocols were employed in which the duration of the prepulse and the interval separating the prepulse and test pulse were varied. The time course for the decay of IgOFFslow following a brief inactivating prepulse was similar to the time course for the recovery of the Na channel QON (QNaRecov). Both IgOFFslow and QNaRecov preceded the recovery of the Na channel (ionic) current. The recovery from inactivation of both the Na current and QNa displayed a similar voltage dependence. These experiments have helped to identify the two components of cardiac IgOFF and, therefore, will facilitate the interpretation of further biophysical and pharmacological studies concerning cardiac Na channel and Ca channel gating charge movements.

A consensus sequence for binding of Lrp to DNA

Lrp (leucine-responsive regulatory protein) is a major regulatory protein involved in the expression of numerous operons in Escherichia coli. For ilvIH, one of the operons positively regulated by Lrp, Lrp binds to multiple sites upstream of the transcriptional start site and activates transcription. An alignment of 12 Lrp binding sites within ilvIH DNA from two different organisms revealed a tentative consensus sequence AGAAT TTTATTCT (Q. Wang, M. Sacco, E. Ricca, C.T. Lago, M. DeFelice, and J.M. Calvo, Mol. Microbiol. 7:883-891, 1993). To further characterize the binding specificity of Lrp, we used a variation of the Selex procedure of C. Tuerk and L. Gold (Science 249:505-510, 1990) to identify sequences that bound Lrp out of a pool of 10(12) different DNA molecules. We identified 63 related DNA sequences that bound Lrp and estimated their relative binding affinities for Lrp. A consensus sequence derived from analysis of these sequences, YAGHAWATTWT DCTR, where Y = C or T, H = not G, W = A or T, D = not C, and R = A or G, contains clear dyad symmetry and is very similar to the one defined earlier. To test the idea that Lrp in the presence of leucine might bind to a different subset of DNA sequences, we carried out a second selection experiment with leucine present during the binding reactions. DNA sequences selected in the presence or absence of leucine were similar, and leucine did not stimulate binding to any of the sequences that were selected in the presence of leucine. Therefore, it is unlikely that leucine changes the specificity of Lrp binding.

Identification of a global repressor gene, rsmA, of Erwinia carotovora subsp. carotovora that controls extracellular enzymes, N-(3-oxohexanoyl)-L-homoserine lactone, and pathogenicity in soft-rotting Erwinia spp

The production of extracellular enzymes such as pectate lyase (Pel), polygalacturonase (Peh), cellulase (Cel), and protease (Prt) is activated by the cell density (quorum)-sensing signal, N-(3-oxohexanoyl)-L-homoserine lactone (HSL); plant signals; and aep genes during postexponential growth of Erwinia carotovora subsp. carotovora 71. Studies with mutants of E. carotovora subsp. carotovora 71 derepressed in exoenzyme production led to the identification of a negative regulator gene, rsmA (rsm, repressor of secondary metabolites). Nucleotide sequencing, transcript assays, and protein analysis established that a 183-bp open reading frame encodes the 6.8-kDa RsmA. rsmA has extensive homology with the csrA gene of Escherichia coli, which specifies a negative regulator of carbon storage. Moreover, the suppression of glycogen synthesis in E. coli by rsmA indicates that the Erwinia gene is functionally similar to csrA. Southern hybridizations revealed the presence of rsmA homologs in soft-rotting and non-soft-rotting Erwinia spp. and in other enterobacteria such as Enterobacter aerogenes, E. coli, Salmonella typhimurium, Shigella flexneri, Serratia marcescens, and Yersinia pseudotuberculosis. rsmA suppresses production of Pel, Peh, Cel, and Prt, plant pathogenicity, and synthesis of HSL in E. carotovora subsp. atroseptica, E. carotovora subsp. betavasculorum, E. carotovora subsp. carotovora, and E. chrysanthemi. In the E. carotovora subsp. carotovora 71, rsmA reduces the levels of transcripts of hslI, a luxI homolog required for HSL biosynthesis. This specific effect and the previous finding that HSL is required for extracellular enzyme production and pathogenicity in soft-rotting Erwinia spp. support the hypothesis that rsmA controls these traits by modulating the levels of the cell density (quorum)-sensing signal.

Phorbol ester-induced priming of superoxide generation by phosphatidic acid-stimulated neutrophils and granule-free neutrophil cytoplasts

This study was undertaken to examine the mechanisms involved in polymorphonuclear leukocyte superoxide release stimulated by exogenous phosphatidic acid (PA). Unlike the immediate burst of superoxide release affected by membrane-permeable dioctanoylglycerol (DiC8-DAG), dioctanoyl phosphatidic acid (DiC8-PA) induced superoxide release after a lag period of 5-20 min. This period was considerably reduced or eliminated when cells were primed by substimulatory levels of phorbol myristate acetate (PMA). Granule-depleted neutrophil cytoplasts also responded to DiC8-PA with a burst of superoxide generation. Activation of the cytoplast superoxide generating system in response to DiC8-PA was also significantly faster after cells had been preexposed to substimulatory levels of PMA, indicating that at least a portion of the priming mechanism was independent of PMA-induced degranulation. To further examine the potential mechanism of PMA priming of responses to PA, we evaluated the activity of neutrophil ecto-phosphatidic acid phosphohydrolase (ecto-PA phosphohydrolase), which generates diacylglycerol from exogenous PA. PMA priming had no discernable effect on the activity of this enzyme. In addition, propranolol, an inhibitor of PA phosphohydrolase, did not selectively inhibit PMA priming of neutrophil responses to DiC8-PA, indicating that priming did not result from acceleration of DiC8-PA hydrolysis. We therefore investigated the possibility that activation of protein kinase C was the basis of the primed response. Several semiselective protein kinase C inhibitors (calphostin C, H-7, and acylmethylglycerol) inhibited DiC8-DAG- and DiC8-PA-induced superoxide release as well as PMA-primed responses to approximately the same extent. These results are consistent with the hypothesis that neutrophil responses to phosphatidate are mediated by diglyceride generated by the action of ecto-PA phosphohydrolase. PMA priming does not result from increased catalytic activity of ecto-PA phosphohydrolase but rather seems to result from potentiation of an intermediate involved in the cells' response to multiple stimuli.

Effects of differentiation and transforming growth factor beta 1 on PTH/PTHrP receptor mRNA levels in MC3T3-E1 cells

TGF beta has opposing effects on osteoblasts which are thought to be differentiation stage dependent; however, little is known concerning the effects of TGF beta on osteoblastic characteristics at different stages of maturation. The purpose of this study was to characterize the pattern of mRNA expression for the PTH/PTHrP receptor during normal osteoblastic differentiation in vitro, and evaluate the effects of TGF beta 1 on PTH/PTHrP receptor and osteocalcin (OCN) steady-state mRNA at different stages of osteoblastic differentiation. MC3T3-E1 preosteoblasts were plated at low density and induced to differentiate with ascorbic acid and beta-glycerophosphate. The first group served as a vehicle control and the remaining five groups received a single 48 h TGF beta 1 (3.0 ng/ml)-pulse staggered on a weekly basis for 30 days. Cell cultures were harvested weekly and evaluated for: steady-state PTH/PTHrP receptor and OCN mRNA levels via northern analysis, calcium and phosphorous levels, bone nodules via Von Kossa staining, alkaline phosphatase enzyme levels, and hydroxyproline levels. Group 1 (control) samples followed a normal pattern of proliferation, extracellular matrix deposition, and mineralization. PTH/PTHrP receptor and OCN mRNA expression increased 8-fold and 10-fold respectively, over the collection periods. When TGF beta 1 was administered during the first 48 h period (group 2) while cells were rapidly proliferating, there was a persistent inhibition of PTH/PTHrP receptor expression and a striking reduction in OCN mRNA expression at all time points. There was also a down-regulation of PTH/PTHrP receptor and OCN expression when TGF beta 1 was administered later during osteoblast differentiation (groups 3-6); however, these effects were not persistent. In addition there was a total lack of bone nodule formation in group two cultures, whereas groups 3-6 had increasing bone nodule formation because the TGF beta 1 was administered later in the culture period. These studies indicate that expression of the PTH/PTHrP receptor increases with osteoblastic differentiation and suggest that TGF beta 1 inhibits osteoblastic maturation with more persistent effects found in less differentiated osteoblastic cells.

Multiple subpial transection for treatment of intractable epilepsy

On the basis of experimental study, we applied multiple subpial transection (MST) to treat 50 patients with intractable epilepsy in which epileptigenic lesion involved functional areas such as pericentral gyrus, postcentral gyrus, Broca's area, Wernicke's area, visual cortex, etc. They were followed up for 6 to 40 months. Complete control of seizures was obtained in 32 patients, significant reduction of seizure (more than 50%) in 13, reduction (less than 50%) in 3, and no effect in 2. The total effective rate was 96%. No functional defect was found in all patients. The mechanism of the disease and surgical technique were discussed in detail. We consider that MST could replace some standard excisional therapy for local epilepsy.

Xwnt-8b: a maternally expressed Xenopus Wnt gene with a potential role in establishing the dorsoventral axis

In amphibian embryos, establishment of dorsal-ventral asymmetry is believed to involve dorsal-ventral differences in vegetally derived mesoderm-inducing signals and/or differences in the competence of animal hemisphere (ectodermal) cells to respond to these signals. Previous studies have shown that certain Wnt proteins can generate an ectopic dorsal axis when misexpressed, and that they do so by modifying the response of ectodermal cells to inducers. None of these Wnt proteins are expressed at an appropriate time to do so in vivo. In this study, we describe the isolation and characterization of a full length cDNA for the Xenopus Wnt gene, Xwnt-8b, whose biological activity and expression pattern suggest that it may be involved in establishment of the dorsoventral axis. Both maternal and zygotic Xwnt-8b transcripts undergo alternative splicing to generate mRNAs which encode two different forms of Xwnt-8b protein. During early cleavage stages Xwnt-8b transcripts are confined primarily to animal hemisphere blastomeres, while zygotically derived Xwnt-8b transcripts are restricted almost exclusively to a band of cells in the prospective forebrain of neurula and tailbud stage embryos. Ectopically expressed Xwnt-8b can completely rescue dorsal development of embryos ventralized by exposure to ultraviolet light, and can induce a complete secondary axis in wild-type embryos. Axis induction is observed only if Xwnt-8b is supplied prior to the onset of zygotic gene transcription. This biological activity, together with the presence of maternal Xwnt-8b transcripts in cells that will be induced to form the dorsal mesoderm, is consistent with the possibility that Xwnt-8b may be the endogenous agent that establishes asymmetry in the response of ectodermal cells to mesoderm-inducing signals, thereby initiating dorsal development.

The effect of levonorgestrel-releasing intrauterine device (20 micrograms/day) (LNG-IUD-20) on the morphological structure of human endometrium: a study of the endometrial factor VIII activity in the women before and after insertion of LNG-IUD-20 by the digital image analysis

The specimens of endometria were obtained from 18 women using an intrauterine device releasing levonorgestrel at 20 micrograms/day (LNG-IUD-20). An immunoperoxidase reaction, PAP method, with the antiserum of Factor VIII as the primary antibody, was carried out in the endometrial biopsies to detect the Factor VIII activity in the endometrial endothelium before and after insertion of LNG-IUD-20. The immunoperoxidase activity was quantitatively assessed by a computer digital image analyser. The results revealed that there were a lower Factor VIII activity in the endometrial endothelial cells after insertion of LNG-IUD-20 (p < 0.001) when compared with the control. From the results of the present study, it is suggested that the synthesis and release of endometrial endothelial Factor VIII might be inhibited by the insertion of LNG-IUD20.

[Treating steroids dependent asthmatic patients with high dose beclomethasone dipropionate aerosol]

In order to provide a more effective alternative therapy for the steroid dependent asthmatic (SDA) patients, 23 SDA patients replaced their oral steroids with high dose beclomethasone dipropionate (1500 micrograms/d) inhalation were investigated. The changes of clinical features, pulmonary function and the Synacthen test were recorded. The results showed that about 82% of the patients replaced their oral steroids completely or partially with the inhalation therapy, the clinical features were improved in 13% of the patients and the failure rate was only 4.4%, the results also revealed that, after replacement, the pulmonary function of the patients were improved (P < 0.05); according to the results of Synacthen test, after alternative therapy for 3-6 months, the damaged reserve power and secretive ability of adrenal cortex of the patients were also partially improved (P < 0.01).

Effects of caffeine on background potassium current in isolated guinea pig ventricular myocytes

We investigated effects of caffeine on inward rectifier potassium current (Ik1) in voltage-clamped ventricular cells by slow ramp depolarization (15 mV/s). Caffeine 10 mM applied in the solution bathing the cells consistently reduced the slope of the current-voltage (I-V) relation over the range of -80 to -40 mV. This effect of caffeine was not prevented by loading cells with BAPTA (1,2-bis(2-aminophenoxy) ethane N,N,N',N'-tetra-acetic acid) to suppress contraction. In the absence of caffeine, reducing extracellular potassium from 5.4 to 2.7 mM caused the expected shift of the reversal potential for current in the negative direction and increased rectification. In low potassium, 10 mM caffeine continued to reduce the slope of the I-V relation. When 2 mM barium was applied to suppress Ik1, any effects of 10 mM caffeine were slight or absent. The observations are consistent with a blocking action of caffeine on Ik1 in guinea pig ventricular myocytes.

Inactivation of rsmA leads to overproduction of extracellular pectinases, cellulases, and proteases in Erwinia carotovora subsp. carotovora in the absence of the starvation/cell density-sensing signal, N-(3-oxohexanoyl)-L-homoserine lactone

The soft-rotting bacterium, Erwinia carotovora subsp. carotovora 71, produces extracellular enzymes such as pectate lyase isozymes (Pels), cellulase (Cel), polygalacturonase (Peh), and protease (Prt). While the extracellular levels of these enzymes are extremely low when the bacterium is grown in salts-yeast extract-glycerol (SYG) medium, the enzymatic activities are highly induced in SYG medium supplemented with celery extract. By transposon (mini-Tn5) mutagenesis, we isolated a RsmA- mutant, AC5070, which overproduces extracellular enzymes; the basal levels of Pel, Peh, and Cel in AC5070 are higher than the induced levels in the RsmA+ parent, AC5047. While Peh production is mostly constitutive in AC5070, Pel, Cel, and Prt production is still inducible with celery extract. The high basal levels of pel-1, pel-3, and peh-1 mRNAs in AC5070 demonstrate that overproduction of the pectolytic enzymes is due to the stimulation of transcription. Using chromosomal DNA flanking mini-Tn5 as a probe, we cloned the wild-type rsmA+ allele, which suppresses Pel, Peh, Cel, and Prt production in both RsmA+ and RsmA- strains. The RsmA- mutant, like its parent, produces N-(3-oxohexanoyl)-L-homoserine lactone (HSL), a starvation/cell density-sensing signal required for extracellular enzyme production. To examine the role of HSL, we constructed HSL-deficient strains by replacing hslI, a locus required for HSL production, with hslI::Tn3HoHo1-Spc. While the basal levels of Pel, Peh, Cel, and Prt are comparable in the RsmA- mutant and its HSL- derivative, these enzymes are barely detectable in the Hsl- derivative of the RsmA+ parent strain.(ABSTRACT TRUNCATED AT 250 WORDS)

[Bioavailability study on xiaohuoluo pills]

According to the relationship between dosage and effect, the time course of analgesic was determined after oral administration of Xiaohuoluo Pills to mice. Based on this experiment, contrasting the commercial pills with the reference preparation, the bioavailability of Xiaohuoluo Pills was studied. It was shown that the bioavailability of different batches of product from the same factory was different. This method was good for the study of compound preparations of Chinese materia medica.

Identification and characterization of genes that are required for the accelerated degradation of mRNAs containing a premature translational termination codon

In both prokaryotes and eukaryotes nonsense mutations in a gene can enhance the decay rate of the mRNA transcribed from the gene, a phenomenon described as nonsense-mediated mRNA decay. In yeast, the products of the UPF1 and UPF3 genes are required for this decay pathway, and in this report we focus on the identification and characterization of additional factors required for rapid decay of nonsense-containing mRNAs. We present evidence that the product of the UPF2 gene is a new factor involved in this decay pathway. Mutation of the UPF2 gene or deletion of it from the chromosome resulted in stabilization of nonsense-containing mRNAs, whereas the decay of wild-type transcripts was not affected. The UPF2 gene was isolated, and its transcript was characterized. Our results demonstrate that the UPF2 gene encodes a putative 126.7-kD protein with an acidic region at its carboxyl terminus (-D-E)n found in many nucleolar and transcriptional activator proteins. The UPF2 transcript is 3600 nucleotides in length and contains an intron near its 5' end. The UPF2 gene is dispensable for vegetative growth, but upf2 delta strains were found to be more sensitive to the translational elongation inhibitor cycloheximide than UPF2+. A genetic analysis of other alleles proposed to be involved in nonsense-mediated mRNA decay revealed that the UPF2 gene is allelic to the previously identified sua1 allele, a suppressor of an out-of-frame ATG insertion shown previously to reduce translational initiation from the normal ATG of the CYC1 gene. In addition, we demonstrate that another suppressor of this cyc1 mutation, sua6, is allelic to upf3, a previously identified lesion involved in nonsense-mediated mRNA decay.

A perfusion chamber developed to investigate thrombus formation and shear profiles in flowing native human blood at the apex of well-defined stenoses

The precipitating event leading to stroke, myocardial infarction, and/or sudden death may be related to the formation of mural thrombus at the site of a ruptured or superficially damaged stenotic plaque. The fluid dynamic properties at atherosclerotic plaques that may be implicated in this thrombus formation have been described in a wide variety of model systems in both the process of plaque rupture and the growth of platelet thrombi. In general, the local fluid dynamic conditions are complex and show major variations from flow in well-defined laminar flow systems. However, no studies have attempted to quantify the effect of stenosis-related disturbances on thrombus formation in native human blood and to compare them with the local fluid dynamics. We developed a parallel-plate perfusion chamber device in which thrombus formation is measured at the "apex" of eccentric stenoses and have correlated such measurements with values of the local fluid dynamics obtained by computer simulation. The extent of stenoses (reduction in the cross-sectional area of the blood flow channel) was 60%, 80%, and 89%, corresponding to "apex" wall shear rates of 2600, 10,500, and 32,000 sec-1, respectively. The wall shear rate in the laminar flow region proximal and distal to the stenoses was 420 sec-1. The surface of the stenosis was purified collagen type III fibrils that were exposed to flowing nonanticoagulated human blood drawn directly from an antecubital vein by a pump placed distally to the perfusion chamber. The resulting blood-collagen interactions were quantified by light microscopy by using a morphometric image analysis technique. Under all conditions studied, platelet thrombus formation at the "apex" was extensive.(ABSTRACT TRUNCATED AT 250 WORDS)

[Bleomycin-induced fibroblast proliferation is inhibited by IH764-3]

It reports that IH764-3 has both therapeutical and prophylactic effect on bleomycin-induced pulmonary fibrosis in rats and mice. The data presented indicate that IH764-3 is a potent inhibitor of the two important ways commonly thought to be the main causes of pulmonary fibrosis induced by bleomycin (BLM): 1) BLM stimulates the alveolar macrophages to secrete fibroblast growth factor (FGF); and 2) BLM increases the proliferation rate of the fibroblast directly. This demonstration of suppression of the stimulative effect of BLM on the fibroblast proliferation by IH764-3 provides direct evidence that IH764-3 could be a promising anti-fibrogenetic drug candidate.

Voltage- and concentration-dependent effects of lidocaine on cardiac Na channel gating charge movements

The effects of lidocaine, a local anesthetic and cardiac antiarrhythmic agent, were studied on cardiac nonlinear Na channel and Ca channel charge movements (gating currents) of 17-day-old embryonic chick ventricular myocytes. Gating currents were recorded following the blockade of all ionic currents and the subtraction of the linear capacity currents (-P/5). From a holding potential of -100 mV the ON charge movement (QON) displayed two kinetic components: a rapidly decaying component associated with Ca channel gating, and a slower component associated with Ca channel gating. A depolarizing prepulse to -50 mV for 125 ms reduced the fast component of QON, with little effect on the slower component. Similarly, 20 microM lidocaine also reduced the fast component of QON (Na channel charge movement) and had little effect on the slower component (Ca channel charge movement). Higher concentrations of lidocaine (125 microM) reduced both the fast and the slower components of QON. The effects of either a prepulse to -50 mV, or 20 microM lidocaine on the steady-state QON/Vm relationship were nearly identical. These results suggest that lidocaine "blocks" cardiac Na (ionic) currents by a reduction in the availability of Na channel charge movement (QON), and that this reduction is similar to that produced by voltage-dependent inactivation.

An epidemiological study on the relationship of ectopic pregnancy and the use of contraceptives in Beijing--the incidence of ectopic pregnancy in the Beijing area. Beijing Collaborating Study Group for Ectopic Pregnancy

The incidence of ectopic pregnancy (EP) was studied through a 3-level monitoring network of maternal and child health care (MCH) in the entire Beijing area, including 82 hospitals, 19 MCH centers and 2 institutes for family planning. A total of 1,420 cases of EP were collected in a sample of 2.7 million women of reproductive age (15-49) during a one-year period from January 1 to December 31, 1990. The cases were confirmed by pathological examination or laparoscopy. In addition, epidemiological surveillance method was used. The results showed that the overall incidence of EP was 0.52 per thousand women of reproductive age (W = Women of reproductive age (15-49)) in the Beijing area, 0.6/1000W in the urban districts and 0.41/1000 in the rural area; 0.67/1000W married women, and 0.05/1000W in the unmarried. For married women, 0.54/1000W for those women using various contraceptive measures and 1.80/1000W for women using no contraceptives. The incidence of EP varies with different contraceptive methods. Female sterilization had the lowest incidence (0.18/1000W) and natural contraceptive measures (rhythm or withdrawal method) had the highest (2.43/1000W). It was 0.65/1000W in IUD users, 0.21/1000W in OC users and 0.57/1000W in couples using condoms or spermicides.

Pseudopregnancy-dependent accumulation of cholesterol sulfate due to up-regulation of cholesterol sulfotransferase and concurrent down-regulation of cholesterol sulfate sulfatase in the uterine endometria of rabbits

The uterine endometria of rabbits induced into pseudopregnancy by intramuscular injection of 17 beta-estradiol, followed by intravenous injection of human chorionic gonadotropin, expressed cholesterol sulfate at a significantly high concentration. The highest concentration of cholesterol sulfate was observed 4 days after the injection of gonadotropin for formation of the corpus luteum, being 10 times higher than that in nonpregnant endometria, and 15.2% of the total cholesterol in the endometrium was converted to the sulfated form, whose percentage in nonpregnant endometrium was 3.2%. However, no significant change in the concentration of gangliosides was observed during the period of pseudopregnancy. In the pseudopregnant endometria, the activity of cholesterol sulfotransferase, a cytosolic thiol enzyme, was increased thirtyfold over that in the nonpregnant endometria, whereas cholesterol sulfate sulfatase, a microsomal enzyme, exhibited approximately one-tenth of the activity in nonpregnant endometria. Arylsulfatase C, but not arylsulfatases A and B, exhibited the same change in activity as cholesterol sulfate sulfatase. Thus, the striking increase in cholesterol sulfate after induction of pseudopregnancy was found to be due to the activation of cholesterol sulfotransferase and the simultaneous inhibition of cholesterol sulfate sulfatase.

Species difference in the modulatory effect of kappa agonist on 5-HT release from ground squirrel and rat hippocampus

Inclusion of the kappa agonist U50488 in the perifusion medium enhanced K(+)-stimulated 5-HT release from ground squirrel hippocampal slices, but reduced 5-HT outflow in both young and old rats' hippocampal slices. The stimulatory effect of U50488 on 5-HT release from ground squirrel hippocampus was not significantly attenuated by the non-specific opioid antagonist naloxone (10(-5) M), but was completely reversed by the specific kappa antagonist nor-BNI (10(-6)M), and the voltage-dependent sodium channel blocker TTX (10(-6)M). In contrast, the inhibitory effect of U50488 on 5-HT release from the young rat hippocampus was attenuated by naloxone (10(-6)M), but not by nor-BNI (10(-6)M) or TTX (10(-6)M). These results illustrate a significant species difference in the modulatory effect of opioids on neurotransmitter release in the hippocampus.

Regulation of neutrophil responses by phosphotyrosine phosphatase

By using immunofluorescent flow cytometry, we observed a profound up-regulation of CD45 on the plasma membrane of neutrophils exposed to low levels of a culture supernatant of the Gram-negative pathogen, Fusobacterium nucleatum (FN). Plasma membranes of neutrophils freshly prepared form human blood possessed little enzymatically active phosphotyrosine phosphatase. The activity of this enzyme was markedly potentiated in plasma membranes prepared from cells preexposed to the FN culture supernatant. This activity was vanadate sensitive and could be immunoprecipitated with anti-CD45 Ab. Cells preexposed to the FN culture supernatant were inhibited in their ability to release superoxide when challenged with the bacterial chemotactic factor, FMLP, but not PMA. The tyrosine kinase inhibitor, genistein, likewise inhibited FMLP but not PMA-induced superoxide release. Pretreatment of neutrophils with vanadate reversed FN-mediated inhibition of FMLP-triggered superoxide release but had no effect on genistein-mediated inhibition of FMLP-induced superoxide release. Of several proteins tyrosine phosphorylated in response to treatment of neutrophils with FMLP, Western analysis revealed one (m.w. approximately 93,000) that was lost when FMLP-stimulated cells were exposed to FN. This effect was inhibited when the cells were preexposed to vanadate. These results are consistent with the hypothesis that plasma membrane tyrosine phosphatase modulates FMLP-induced superoxide release by reversing the effects of tyrosine kinases activated in the initial phases of cell stimulation.

Regulation of neutrophil responses by phosphotyrosine phosphatase

By using immunofluorescent flow cytometry, we observed a profound up-regulation of CD45 on the plasma membrane of neutrophils exposed to low levels of a culture supernatant of the Gram-negative pathogen, Fusobacterium nucleatum (FN). Plasma membranes of neutrophils freshly prepared form human blood possessed little enzymatically active phosphotyrosine phosphatase. The activity of this enzyme was markedly potentiated in plasma membranes prepared from cells preexposed to the FN culture supernatant. This activity was vanadate sensitive and could be immunoprecipitated with anti-CD45 Ab. Cells preexposed to the FN culture supernatant were inhibited in their ability to release superoxide when challenged with the bacterial chemotactic factor, FMLP, but not PMA. The tyrosine kinase inhibitor, genistein, likewise inhibited FMLP but not PMA-induced superoxide release. Pretreatment of neutrophils with vanadate reversed FN-mediated inhibition of FMLP-triggered superoxide release but had no effect on genistein-mediated inhibition of FMLP-induced superoxide release. Of several proteins tyrosine phosphorylated in response to treatment of neutrophils with FMLP, Western analysis revealed one (m.w. approximately 93,000) that was lost when FMLP-stimulated cells were exposed to FN. This effect was inhibited when the cells were preexposed to vanadate. These results are consistent with the hypothesis that plasma membrane tyrosine phosphatase modulates FMLP-induced superoxide release by reversing the effects of tyrosine kinases activated in the initial phases of cell stimulation.

Effects of ascorbic acid on collagen matrix formation and osteoblast differentiation in murine MC3T3-E1 cells

Treatment of mouse MC3T3-E1 cells with ascorbic acid initiates the formation of a collagenous extracellular matrix and synthesis of several osteoblast-related proteins. We recently showed that ascorbic acid dramatically increases alkaline phosphatase and osteocalcin mRNAs and that this induction is blocked by inhibitors of collagen triple-helix formation (Franceschi and Iyer, J Bone Miner Res 7:235). In the present study, the relationship between collagen matrix formation and osteoblast-specific gene expression is explored in greater detail. Kinetic studies revealed that ascorbic acid increased proline hydroxylation in the intracellular procollagen pool within 1 h and stimulated the cleavage of type I collagen propeptides beginning at 2.5 h. Mature alpha 1(I) and alpha 2(I) collagen components were first detected at 10 h and continued to increase in both cell layer and culture medium for up to 72 h. Ascorbic acid also increased the rate of procollagen secretion from cell layers to culture medium. The secretion of another matrix protein, fibronectin, was only slightly affected. Alkaline phosphatase or its mRNA was first detected 2-3 days after ascorbic acid addition, but osteocalcin mRNA was not seen until day 6. Two inhibitors of collagen triple-helix formation, ethyl-3,4-dihydroxybenzoate and 3,4-dehydroproline, inhibited procollagen hydroxylation and alkaline phosphatase induction. 3,4-Dehydroproline also inhibited the induction of alkaline phosphatase and osteocalcin mRNAs. Surprisingly, induction was not blocked if cells were exposed to ascorbic acid before inhibitor addition. Alkaline phosphatase was also partially inhibited if cells were grown in the presence of purified bacterial collagenase. These results indicate that the induction of osteoblast markers by ascorbic acid does not require the continuous hydroxylation and processing of procollagens and suggest that a stable, possibly matrix-associated signal is generated at early times after ascorbic acid addition that allows subsequent induction of osteoblast-related genes.

Parallel up-regulation of CD11B and CD45 on neutrophilic leukocytes exposed to soluble factors of oral pathogens

We tested culture supernatants from a battery of oral bacterial strains for their ability to influence the expression of CD11b and CD45 on the neutrophil plasma membrane. Several bacterial extracts stimulated the up-regulation of both CD11b and CD45 simultaneously. Two supernatants in particular (a clinical isolate of A. actinomycetemcomitans and F. nucleatum ATCC25586) potently stimulated the deployment of CD11b and CD45 from their intracellular storage site to the plasma membrane. Both supernatants inhibited superoxide release stimulated by exposure of neutrophils to formyl methionyl leucyl phenylalanine (FMLP) but had variable effects on superoxide release stimulated by phorbol myristate acetate (PMA). The ability of products of oral bacteria to modulate neutrophil plasma membrane antigen composition may regulate functional reactivity and thus be an important factor in the pathogenesis of periodontal infection and inflammation.

Angiotensin II suppresses Na+ currents in bovine adrenal chromaffin cells

We investigated the effects of angiotensin II (ANG II) on the voltage-dependent Na+ channel currents (INa) recorded from bovine adrenal medullary chromaffin cells (BCCs) under whole-cell voltage clamp. Angiotensin II reversibly reduced the peak INa in a dose-dependent fashion. Inhibition was observed at a concentration of 1 nM (6.3 +/- 1.4%, mean +/- SEM) and reached a maximum at 1 microM (35 +/- 3.8%), with a half-maximal effect at 11.6 nM. The ANG II-induced inhibition resulted from a reduction in peak conductance (control, 7.2 +/- 0.7 nS; ANG II 4.3 +/- 0.5 nS; p < 0.01). Angiotensin II had no effect on the reversal potential or the decay time of INa. In addition, the V1/2 and k values, two parameters that describe the voltage dependence of INa for both steady-state activation and inactivation, were not affected by ANG II. The response to ANG II (1 microM) had a delay and attained maximum inhibition in 0.9 +/- 0.2 min (n = 10). Recovery from the effect was slow and took 3.5 +/- 0.8 min (n = 10) after the application of ANG II had been terminated. The inhibitory effects of ANG II were effectively blocked by a specific ANG II receptor antagonist. [Sar1, Val5, Ala8]ANG II. The present study demonstrates that ANG II inhibits voltage-dependent INa+ channel currents in BCCs via a specific receptor-coupled mechanism. The prolonged time course of the ANG II response indicates a possible involvement of second messenger(s) mediating this inhibition.

The anti-proliferative effects of nicotinamide and 3-aminobenzamide on human smooth muscle cells in vitro

The proliferation of cultured human arterial smooth muscle cells (HASMC) was suppressed by nicotinamide and its analogue, 3-aminobenzamide, in a concentration-dependent manner, based on cell count and [3H]thymidine incorporation into DNA. The addition of 10 and 15 mM nicotinamide, or 6 mM 3-aminobenzamide, to HASMC, for 96 h, resulted in a 19.3%, 44% and 41.5% reduction of cell growth and inhibition of DNA synthesis. Since c-myc protooncogene expression has previously been correlated with cell proliferation, the steady state level of its mRNA was determined in control and treated HSMC by Northern analysis, following a 1 h treatment with the respective chemicals. Whereas c-myc mRNA was suppressed by nicotinamide in proportion to its ability to reduce HASMC growth, down regulation of c-myc by 3-aminobenzamide was much less than the observed antiproliferative effect. These results suggest that the growth regulatory properties of nicotinamide and 3-aminobenzamide in HASMC are probably unrelated to their activity in controlling c-myc gene expression.

Frequency tuning of a distributed feedback dye laser with two transmission gratings

Distributed feedback dye lasers, which use a holographic grating, present a very simple and reliable way to generate ultrashort pulses. We have developed a new technique for wavelength tuning of this type of laser by projecting the image of a second grating into the dye cell. Single-line operating and tuning was demonstrated with transform-limited output pulses on a picosecond time scale.

Difference of spectral superbroadening behavior in Kerr-type and non-Kerr-type liquids pumped with ultrashort laser pulses

The spectral superbroadening behavior of forward coherent radiation from a 10-cm-long liquid-filled cell is investigated by using an ultrashort (∼0.5 ps) and intense (∼10 GW/cm(2)) laser pulse as the pump source. Five different transparent liquids (heavy water, water, carbon tetrachloride, benzene, and carbon disulfide) have been studied with a special experimental design that can distinguish the predominant contributions from the various possible mechanisms. Under the same pump condition, a very wide and symmetrical superbroadening (continuum) is observed on both the Stokes and the anti-Stokes side of the pump line for non-Kerr-type liquids such as heavy water and water, whereas only a red-shifted spectral broadening can be observed on the Stokes side for Kerr-type liquids such as carbon disulfide and benzene. For an explanation of the latter behavior, the dominant contributions from stimulated Rayleigh-Kerr and Raman-Kerr scattering are proposed.

Thermoregulatory responses following injection of 5-hydroxytryptamine into the septohippocampal complex in rats

The present study investigated the change in thermoregulatory responses following microinjection of 5-hydroxytryptamine (5-HT) into the lateral septum and the hippocampus of unanesthetized, unrestrained rats. Intraseptal injection of 5-HT (5 to 20 micrograms) caused a dose-related fall in core temperature (Tb), which was associated with a decrease in heat production (HP). As the decrease in HP can not completely account for the magnitude of the decrease in Tb, increase in heat loss may also be involved in the 5-HT-induced hypothermia. In contrast to observed changes following intraseptal injection, no significant change in either Tb or HP was observed after microinjection of the same doses of 5-HT into the hippocampal areas, indicating that the hypothermic response to intraseptal injection of 5-HT is site specific. Further, the hypothermic response to intraseptal injection of 5-HT was only attenuated by systemic pretreatment with cyproheptadine, but not by naloxone or scopolamine, indicating that the hypothermic response is mediated by 5-HT receptor, but not by endogenous opioid and cholinergic systems.

Effects of 3,6-dimethamidodibenzopyriodonium citrate on slow inward calcium current in isolated guinea pig ventricular cells

The effects of 3,6-dimethamidodibenzopyriodonium citrate (I-65) on action potentials and slow inward calcium current (I(si)) were examined on isolated guinea pig ventricular myocardial cells. I-65 (30-100 mumol.L-1) depressed the action potential duration at 20% repolarization (APD20) and, under voltage-clamp conditions, reduced the amplitude of I(si) without changing the I-V relations. I-65 also showed use-dependent effects on I(si). These suggest that I-65 may block I(si) by acting on the inactivated state of Ca channels.

Human cervical epidermal carcinoma-associated intracellular localization of glycosphingolipid with blood group A type 3 chain

A monoclonal antibody, MRG-1, was produced by immunizing a mouse with a human ovarian mucinous cyst adenocarcinoma-derived cell line, RMUG-L. By immunohistochemical staining, the antigen was found to be exclusively localized in the intracellular structures of the cells used as the antigen and of the epithelial cells in normal human cervical glands. However, although the antigen was predominantly detected in the plasma membrane and the intercellular structure of the middle layer of normal human cervical squamous epithelium (92%), it was also contained in the intracellular structure of cervical epidermal carcinoma at a high frequency (80%). The striking difference in the distribution of the MRG-1 antigen between normal and cancerous tissues was found to be a cervical carcinoma-associated phenomenon and a useful tumor marker for immunohistochemical examination. Since the antigen was found to be of a blood group A-related nature by immunohistochemical staining of the tissues and to be a glycosphingolipid, it was purified from human erythrocytes of blood group A, and the structure was concluded to be GalNAc alpha 1-3Gal(2-1 alpha Fuc)beta 1-3GalNAc alpha 1-3Gal(2-1 alpha Fuc)-beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1' Cer, blood group A type 3 chain-containing glycosphingolipid, by NMR, negative ion FABMS and permethylation analysis. In the subcellular localization analysis of the antigen, type 3-A glycosphingolipid antigen was detected in the Golgi body and the microsomes of RMUG-L cells, and the distribution coincided with the finding by immunohistochemical staining. In addition, in cervical epidermal carcinoma, although the blood group A, mainly type 2-A chain, was localized in the plasma membrane and the intercellular structure, the blood group A type 3 chain was selectively found in the perinuclear structure. Also, the blood group A type 3 chain in cervical dysplasia as well as that in normal cervix was predominant in the plasma membrane. Thus, the selective intracellular localization of blood group A type 3 chain was a phenomenon characteristic of cervical epidermal carcinoma and the carcinoma in situ.

Deficiency of phosphatidylinositol-linked membrane proteins on erythrocytes of different subpopulations in paroxysmal nocturnal hemoglobinuria

The surface phosphatidylinositol (PI)-linked proteins on membrane of paroxysmal nocturnal hemoglobinuria (PNH) erythrocytes (PNHE) was analysed by a flowcytometer (FACS 420). It was found that the loss of acetylcholinesterase (AchE) and decay accelerating factor (DAF), two PI-linked proteins, from cell membrane of PNHE was not synchronous. The hemolysis rates of DAF (-) and AchE (-) PNHE were much higher than that of mixed population in cobra-venom factor (CoF) lysis test. Intact PNHE remaining after CoF lysis had relatively lower immunofluorescent labeling rate of AchE on membrane in comparison with normal erythrocytes. It implied that this subpopulation, in spite of being insensitive to complement lysis, was still abnormal in terms of the amount of PI-linked protein on cell membrane. When these intact PNHE remaining after CoF lysis were incubated with activated polymorphonuclear leukocytes (PMN) for three hours, immunofluorescent labeling of AchE on PNHE was prominently decreased. This indicated that reactive oxidants released from activated PMN might injure PI-linked proteins.

Experimental study of the effect of IH764-3 on pulmonary fibrosis

IH764-3 is a potent component isolated from Salvia miltiorrhiza. We have studied the effect of IH764-3 on experimental pulmonary fibrosis in rats and mice treated with a single intratracheal instillation of bleomycin-A6. Three groups of animals were assigned as BLM+saline, BLM+IH764-3 and normal control. The results indicated that in the treated group, lung coefficient, surfactant, hydroxyproline content and FGF activity were significantly lower than those in the control group (P < 0.05, 0.05, 0.001 and 0.05, respectively). Electron microscopic examination showed that pulmonary ultrastructure was markedly better in the treated group: type II alveolar epithelial cells, infiltrating inflammatory cells, proliferating collagen-forming cells, collagen and elastic fibers were obviously fewer in the treated group. These results demonstrate that IH764-3 has prophylactic and therapeutic effects on pulmonary fibrosis.

[Studies on insecticidal ingredients from culture supernatant of Bacillus thuringiensis]

Studies on the insecticidal activity of culture supernatant of Bacillus thuringiensis var. kurstaki HD-1, by centrifugation, column chromatography, protein sequence determination, bioassay and other methods. Found that insecticidal activity of culture supernatant appeared on synchronism with cells lysis. Main insecticidal ingredients of culture supernatant is toxin protein of 60 kilodaltons (kDa). Analyse hat purified the toxin protein, we find that its amino acid composition was similar with 135-kDa P1 protein, and its sequence of N-terminal 18 amino acid was same with that of part of the P1 protein. The results presented here provided that the toxin protein was the same source with the P1 protein. Further found that supernatant have synergizing action on the sediment of culture.

Widely tunable all-solid-state optical parametric oscillator for the visible and near infrared

An all-solid-state optical parametric oscillator (OPO) has been developed in which the signal and idler waves can be tuned over the ranges 455-665 and 760-1620 nm, respectively, with the potential for covering the entire range 420-2300 nm. The OPO uses a critical type I phase-matching geometry in lithium triborate and is pumped at 355 nm by frequency-tripled radiation from a diode-laser-pumped Nd:YAG laser. Oscillation thresholds (minimum 0.3 mJ), pump depletions (>35%), and linewidths of the OPO are reported.

The modulatory effects of mu and kappa opioid agonists on 5-HT release from hippocampal and hypothalamic slices of euthermic and hibernating ground squirrels

To elucidate the role of opioids in regulating hibernation, the modulatory effects of different opioids on 35 mM K(+)-stimulated [3H]-5-HT release from brain slices were examined in the Richardson's ground squirrels. DAGO ([D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin), a specific mu agonist, evoked a significant dose-dependent (10(-7)-10(-5) M) inhibition of K(+)-stimulated 5-HT release from hippocampal slices of the non-hibernating squirrels. The inhibitory effect of DAGO was attenuated by either the opioid antagonist naloxone (10(-6) M) or the voltage dependent sodium channel blocker tetrodotoxin (TTX, 10(-6) M). The inhibitory effect of DAGO persisted in the hibernating squirrels; however, a ten fold higher concentration of DAGO (10(-6)-10(-5) M) was required to elicit a significant inhibition. In contrast, kappa agonist U50488 (10(-5) M) exerted a significant enhancement of K(+)-stimulated 5-HT release from hippocampal slices of the non-hibernating squirrels. This enhancement was blocked by either the specific kappa antagonist nor-binaltorphimine (10(-6) M) or TTX (10(-6) M). However, in the hibernating squirrels, the stimulatory effect of U50488 (10(-5) M) on 5-HT release was absent. DAGO and U50488 had no modulatory effects on K(+)-stimulated 5-HT release from the hypothalamic slices of either the non-hibernating or hibernating squirrels. These results demonstrate that the modulatory effects of opioids on 5-HT release are receptor-specific and state-dependent, indicating the complex nature of the roles of different opioids in regulating hibernation.

Germline variable region gene segment derivation of human monoclonal anti-Rh(D) antibodies. Evidence for affinity maturation by somatic hypermutation and repertoire shift

To date, there has been no systematic study of the process of affinity maturation of human antibodies. We therefore sequenced the variable region genes (V genes) of 14 human monoclonal antibodies specific for the erythrocyte Rh(D) alloantigen and determined the germline gene segments of origin and extent of somatic hypermutation. These data were correlated with determinations of antibody affinity. The four IgM antibodies (low affinity) appear to be derived from two germline heavy chain variable region gene segments and one or two germline light chain variable region gene segments and were not extensively mutated. The 10 IgG antibodies (higher affinity) appear to be derived from somatic hypermutation of these V gene segments and by use of new V gene segments or V gene segment combinations (repertoire shift). Affinity generally increased with increasing somatic hypermutation; on average, there were 8.9 point mutations in the V gene segments of the four IgM antibodies (Ka = 1-4 x 10(7)/M-1) compared with 19 point mutations in the V gene segments of the 10 IgG antibodies. The four highest affinity antibodies (Ka = 0.9-3 x 10(9)/M-1) averaged 25.5 point mutations. The use of repertoire shift and somatic hypermutation in affinity maturation of human alloantibodies is similar to data obtained in inbred mice immunized with haptens.

Retention of C60 and C70 fullerenes on reversed-phase high-performance liquid chromatographic stationary phases

The separation of C60 and C70 fullerenes on four different polysiloxane stationary phases was examined. It was determined that polar solvents can be used as mobile phases effectively for the separation of fullerene molecules. Unlike previously published work, a polymeric octadecyl siloxane (ODS) stationary phase provided higher separation factors for C70/C60 than did monomeric ODS stationary phases or phenyl substituted stationary phases. For example, for a methanol-diethyl ether (50:50, v/v) mobile phase and C60, k' approximately 5.0 separation factors, alpha = 3.3, were achieved with polymeric ODS compared to alpha = 2.2, with a monomeric ODS stationary phase. A linear solvation energy relationship (LSER) was used to model the importance of solvent interactions and stationary phase interaction to solute retention.

Generation of intense 10-ps, 193-nm pulses using simple distributed feedback dye lasers and an ArF(*) amplifier

A pair of holographic distributed feedback dye lasers is used to generate 10-ps pulses at two selected wavelengths that are mixed in a BBO crystal to produce a pulse ~ 10 ps in duration at 193 nm. This seed pulse is subsequently amplified in an ArF(*) excimer laser to an energy of 10-15 mJ with <40 microJ in amplified spontaneous emission. The pulses are nearly transform limited and diffraction limited.

The effect of IH764-3 on fibroblast proliferation and function

The effect of IH764-3, a potent component isolated from Salvia miltiorrhiza, on the proliferation and function of cultured fibroblasts was studied. It was found that the fibroblast growth curve had a dose-dependent relationship with IH764-3 concentration. The incorporation of 3H-TdR and 3H-proline into fibroblasts was significantly inhibited by IH764-3, and calmodulin, fibronectin and thrombospondin contents in the test group were obviously lower than those in the control group. Flow cytometry showed that in the IH764-3-treated group, the percentage of cells in G0/G1 phase was higher than that in the control. Electron microscopic observation (TEM and SEM) showed that in the treated group, collagen secretion was decreased. All of these results indicate that IH764-3 exerts a direct inhibitory effect on fibroblast proliferation and affects their ability to synthesize collagen.

All-solid-state optical parametric oscillator for the visible

An all-solid-state optical parametric oscillator (OPO) with signal and idler waves tunable over the ranges 481-457 and 1355-1590 nm, respectively, has been developed. Radiation at 1064 nm from a diode-laser-pumped Nd:AG laser (delivering 10-mJ Q-switched pulses of 18-ns duration at rates of 10-100 Hz) is frequency tripled at efficiencies near 30% and then used to pump the lithium triborate OPO, thus an all-solid-state configuration is realized. Oscillation thresholds (0.4 mJ), pump depletions (50%), external efficiencies (27%), and temperature-tuning rates (signal -0.11 nm/ degrees C, idler +0.87 nm/ degrees C) for the OPO are reported.

State-dependent variation in the inhibitory effect of [D-Ala2, D-Leu5]-enkephalin on hippocampal serotonin release in ground squirrels

Accumulated evidence has suggested that increased endogenous opioid activities may facilitate the onset of hibernation either directly or possibly through modulation of other neurotransmitter systems. The seasonal change of [D-Ala2, D-Leu5]-enkephalin (DADLE), a delta receptor agonist, in modulating K+ (35 mM)-induced [3H]-5-hydroxytryptamine (5-HT) release from the hippocampal and hypothalamic slices of euthermic and hibernating Richardsons' ground squirrels was therefore investigated. DADLE (0.1-10 microM) had no effect on 5-HT release in the hypothalamic slices but elicited a dose-related inhibition on [3H]-5-HT release from the hippocampal slices of the euthermic ground squirrel. The inhibitory effect of DADLE was completely reversed by naloxone (10 microM), but not by tetrodotoxin (1 microM). In contrast, DADLE failed to alter the K(+)-induced 5-HT release from the hippocampal slices of the hibernating ground squirrel. This state-dependent reduction in responsiveness to an opioid is consistent with the hypothesis that enhanced endogenous opioid activity in the hibernating phase could lead to down regulation of the opioid receptors and minimize its inhibition on hippocampal serotonergic activity. A high 5-HT activity would inhibit midbrain reticular activating system indirectly through non-serotonergic fibers, which in turn facilitate the onset or maintenance of hibernation.

New Taxanes from Taxus chinensis

Two new taxane diterpenes, decinnamoyltaxagifine ( 3) and decinnanioyltaxagifine acetate ( 2), have been isolated from the leaves and stems of TAXUS CHINENSIS. Their structures were elucidated by spectroscopic methods. Their (13)C-NMR chemical shifts were assigned.