Inhibitory effect of suberogorgin on acetylcholinesterase

AIM

To study the selection, reversibility, and kinetics of suberogorgin (Sub) on acetylcholinesterase (AChE).

METHODS

The human plasma was used as butyrylcholinesterase (BuChE). The activity of ChE was determined with colorimetry.

RESULTS

Sub obviously inhibited the AChE in vitro with pl50 4.03, 4.92, 3.82, and 4.67 in RBC membranes (of rat and human) and tissue extracts (of rat brain and earthworm dorsal muscle), respectively. No inhibition on BuChE was observed. The inhibition of Sub on AChE was far lower than that of physostigmine, but was close to that of galanthamine. Sub decreased the AChE activity to the lowest within 3 min after it was incubated with AChE. Centrifugalization washing reactivated the AChE which had been inhibited by Sub. The double-reciprocal plots of different concentrations of Sub on AChE showed parallel lines.

CONCLUSION

Sub was a selective, reversible, and contra-competetive inhibitor of AChE at the binding site on the peripheral anion region of AChE.

Comparison of immunocytologic localization of insulin-like growth factor binding protein-4 in normal and polycystic ovary syndrome human ovaries

The cytologic localization and cellular levels of insulin-like growth factor binding protein-4 (IGFBP-4) in follicular and stromal compartments of normal and polycystic ovary syndrome (PCOS) ovaries during follicular growth and regression were investigated by the avidin/biotin immunoperoxidase method with a polyclonal antibody to human IGFBP-4, and a comparative assessment of IGFBP-4 expression in normal and PCOS ovaries was provided. In normal human ovaries, IGFBP-4 was immunolocalized to the oocyte throughout follicular growth, while the surrounding granulosa and theca cells were negligible for IGFBP-4 immunostaining in primordial, preantral and antral follicles. IGFBP-4 immunostaining became apparent, however, in the lutein cells of corpora lutea and the granulosa and theca cells of atretic follicles. In PCOS ovaries, prominent immunostaining for IGFBP-4 was apparent not only in the oocyte, but also in the surrounding granulosa cells in preantral follicles. In antral follicles from PCOS women without hyperinsulinemia, IGFBP-4 immunostaining was more prominent in the granulosa cells than the theca cells, whereas in antral follicles from PCOS women with hyperinsulinemia IGFBP-4 immunostaining was more prominent in the theca cells than the granulosa cells. Furthermore, in atretic follicles within PCOS ovaries IGFBP-4 immunostaining was prominent in the theca cells, regardless of the association of hyperinsulinemia. These results demonstrate for the first time that there is a great difference in cellular expression of IGFBP-4 between normal and PCOS human ovaries. In light of the high affinity of IGFBP-4 for IGF-1, the abundant expression of IGFBP-4 in granulosa and theca cells of preantral and antral follicles of PCOS ovaries may lead to decreases in the bioavailability of IGF-I in those follicles. The decrease in IGF-I-mediated stimulation of gonadotropin actions on granulosa and theca cells in preantral and antral follicles may impair the induction of aromatase activity, causing an androgenic microenvironment which is characteristic of atretic follicles and PCOS follicles.

Effects of suberogorgin and its derivates on learning and memory in mice

AIM

To study the relationship between the effects of suberogorgin (Sub) and its derivates on memory and their anti-acetylcholinesterase (AChE) actions.

METHODS

The step-down latency (SDL) and the escape latency (EL) of mice were determined at the same time in a passive avoidance task after Sub, N-suberogorgamide-N-N-dicyclohexyl urea (Sub-DU), or N-cyclohexyl suberogorgamide (N-CS) was injected i.p. The AChE activities in brain hemogenates were determined with colorimetry.

RESULTS

Sub 1.9, Sub-DU 3.0, or physostigmine (Phys) 0.15 mg.kg-1 obviously lengthened the SDL by 195%, 271%, and 210%, and shortened the EL by 56%, 61%, and 33%, and the two formers inhibited the brain AChE activities by 17% and 19%, respectively in aging (3-4 months) mice. These actions were decreased in a dose-dependent manner when Sub or Sub-DU was increased to 2.9-4.3 or 4.5-6.7 mg.kg-1 respectively. Sub 1.9, Sub-DU 2.0, and Phys 0.15 mg.kg-1 also lengthened the SDL by 187%, 209%, and 152%, and shortened the EL by 52%, 62%, and 57%, respectively in aged (12-14 months) mice. Sub 1.3-1.9, Sub-DU 0.9-2.0, or Phys 0.15 mg.kg-1 reversed the cycloheximide- or scopolamine-induced disruptions of memory retention. No obvious effect of N-CS on the acquisition of memory and the AChE activity in mice was observed.

CONCLUSION

The improvements of Sub and Sub-DU on memory were chiefly related to their anti-AChE actions.

Tyrosine phosphorylation of extracellular signal-regulated protein kinase 4 in response to growth factors

Extracellular signal-regulated protein kinases (ERKs) are members of the mitogen-activated protein kinase family that are rapidly phosphorylated and activated in response to various extracellular stimuli, including growth factors. Of these, the ERK1 and ERK2 forms are by far the most abundant and the most studied. Much less is known about other ERK forms, including one previously designated ERK4 on the basis of its cross-reactivity with ERK1 and ERK2. We report here that ERK4 in rat PC12 pheochromocytoma cells can be immunoprecipitated by anti-ERK antiserum R2 and have used this re-agent to characterize this species further. We find that ERK4 rapidly becomes tyrosine-phosphorylated in response to nerve growth factor (NGF) and epidermal growth factor (EGF) and, to a lesser degree, in response to insulin and a permeant cyclic AMP analogue. As in the case of ERK1 and ERK2, tyrosine phosphorylation of ERK4 occurs by a ras-dependent pathway in response to NGF and EGF and shows prolonged kinetics for NGF but not EGF treatment. Recognition by multiple antisera directed against various domains of ERK1 supports classification of ERK4 within the ERK family; however, two-dimensional gel analysis clearly distinguishes ERK4 from isoforms of ERK1. These findings thus reveal an additional member of the ERK family that is responsive to growth factors and that could play a distinct role in intracellular signaling.

The effect of anisodamine on cerebral resuscitation of rats in acute cerebral ischemia from cardiac arrest

In order to investigate the mechanisms of acute cerebral ischemia, and to look for effective drugs on cerebral resuscitation, we made a model of acute complete global brain ischemia, reperfusion and resuscitation on rats according to Garavilla's method. Our results showed that the event of cerebral ischemia and reperfusion injury could result in the increase of total brain calcium content, and anisodamine has the same reducing brain calcium contents as diltiazem's, while improving neurological outcome and alleviating injury to neurons.

Genetic enhancement of RNA-processing defects by a dominant mutation in B52, the Drosophila gene for an SR protein splicing factor

SR proteins are essential for pre-mRNA splicing in vitro, act early in the splicing pathway, and can influence alternative splice site choice. Here we describe the isolation of both dominant and loss-of-function alleles of B52, the gene for a Drosophila SR protein. The allele B52ED was identified as a dominant second-site enhancer of white-apricot (wa), a retrotransposon insertion in the second intron of the eye pigmentation gene white with a complex RNA-processing defect. B52ED also exaggerates the mutant phenotype of a distinct white allele carrying a 5' splice site mutation (wDR18), and alters the pattern of sex-specific splicing at doublesex under sensitized conditions, so that the male-specific splice is favored. In addition to being a dominant enhancer of these RNA-processing defects, B52ED is a recessive lethal allele that fails to complement other lethal alleles of B52. Comparison of B52ED with the B52+ allele from which it was derived revealed a single change in a conserved amino acid in the beta 4 strand of the first RNA-binding domain of B52, which suggests that altered RNA binding is responsible for the dominant phenotype. Reversion of the B52ED dominant allele with X rays led to the isolation of a B52 null allele. Together, these results indicate a critical role for the SR protein B52 in pre-mRNA splicing in vivo.

[Familial exudative vitreoretinopathy]

Familial exudative vitreoretinopathy (FEVR) is an autosomal dominant inherited disease. The developmental abnormality of retinal vessels is the basis of various lesions in FEVR. 11 affected members (21 eyes) from 5 families with FEVR were studied. The emphasis was placed on describing the changes of fundus and fundus fluorescein angiography of the disease. Argon laser photocoagulation was performed on 8 patients (14 eyes) and they were followed for 5 approximately 14 months. The diagnosis, differential diagnosis, complications and treatment of FEVR were discussed with some materials in this paper.

Comparative pharmacology of epibatidine: a potent agonist for neuronal nicotinic acetylcholine receptors

Pharmacological properties of the (+)- and (-)-isomers of synthetic epibatidine, exo-2-(6-chloro-3-pyridyl)-7-azabicyclo-[2.2.1]heptane, were compared with nicotine and acetylcholine on several subtypes of chicken and human nicotinic acetylcholine receptors (AChRs). Both isomers of epibatidine behaved as extremely potent full agonists on chicken (alpha 3 beta 2, alpha 3 beta 4, alpha 4 beta 2, alpha 7, and alpha 8) and human (alpha 3 beta 2, alpha 3 beta 4, and alpha 7) neuronal AChRs expressed in Xenopus oocytes. Currents induced by epibatidine were effectively blocked by the nicotinic antagonists hexamethonium and mecamylamine. Apparent affinity was 100 to 1000-fold higher for epibatidine than for nicotine or acetylcholine. EC50 values ranged from 1 nM (for homomeric chicken alpha 8) to 2 microM (for homomeric chicken alpha 7). Epibatidine showed comparatively lower affinity for muscle-type AChRs from Torpedo and humans (EC50 values, 1.6 and 16 microM respectively). In binding assays, epibatidine was used on AChR subtypes immunoisolated from chicken brain and retina (alpha 4 beta 2, alpha 7, and alpha 8), the human neuronal cell line SH-SY5Y (alpha 3 and alpha 7), Torpedo electric organ (alpha 1 beta 1 gamma delta), or the human rhabdomyosarcoma cell line TE671 (alpha 1 beta 1 gamma delta). Both isomers of epibatidine exhibited extremely high affinity for all neuronal AChRs tested, with KI values ranging from 0.6 pM (human alpha 3 AChRs) to 0.6 microM (chicken alpha 7 AChRs). In contrast, epibatidine had lower affinity for Torpedo muscle-type AChRs (KI approximately 5 microM). Racemic [3H]epibatidine was an effective labeling reagent for human alpha 3 beta 2 AChRs, exhibiting a KD (0.14 nM) similar to the KI values observed for unlabeled (+)-epibatidine (0.23 nM) or (-)-epibatidine (0.16 nM).

Elimination of glycosylation heterogeneity affecting heparin affinity of recombinant human antithrombin III by expression of a beta-like variant in baculovirus-infected insect cells

In order to promote homogeneity of recombinant antithrombin III interactions with heparin, an asparagine-135 to alanine substitution mutant was expressed in baculovirus-infected insect cells. The N135A variant does not bear an N-linked oligosaccharide on residue 135 and is therefore similar to the beta isoform of plasma antithrombin. Purified bv.hat3.N135A is homogeneous with respect to molecular mass, charge and elution from immobilized heparin. Second-order rate constants for thrombin and factor Xa inhibition determined in the absence and presence of heparin are in good agreement with values established for plasma antithrombin and these enzymes. Based on far- and near-UV CD, bv.hat3.N135A has a high degree of conformational similarity to plasma antithrombin. Near-UV CD, absorption difference and fluorescence spectroscopy studies indicate that it also undergoes an identical or very similar conformational change upon heparin binding. The Kds of bv.hat3.N135A for high-affinity heparin and pentasaccharide were determined and are in good agreement with those of the plasma beta-antithrombin isoform. The demonstrated similarity of bv.hat3.N135A and plasma antithrombin interactions with target proteinases and heparins suggest that it will be a useful base molecule for investigating the structural basis of antithrombin III heparin cofactor activity.

Deletion of a conserved juxtamembrane sequence in Trk abolishes NGF-promoted neuritogenesis

Deletion of a conserved juxtamembrane sequence (KFG) in the Trk NGF receptor resulted in impaired neurite outgrowth, somatic hypertrophy, and induction of c-fos, c-jun, and TIS1 immediate-early genes. In contrast, these receptors retained the ability to mediate NGF-promoted survival and TIS8 and TIS11 immediate-early gene induction. The mutated receptor also mediated unimpaired autophosphorylation; SHC, PLC-gamma 1, and ERK tyrosine phosphorylation; and PI-3 kinase and ERK activation. However, SNT protein tyrosine phosphorylation, which wild-type receptors mediate via a ras-independent pathway, was undetectable. These findings indicate that the KFG sequence is indispensable for activating a ras-independent NGF signaling pathway involved in promoting neuronal differentiation and highlight potential roles of non-tyrosine-containing receptor domains in growth factor signal transduction.

NMR study of the cold, heat, and pressure unfolding of ribonuclease A

The reversible cold, heat, and pressure unfolding of RNase A and RNase A--inhibitor complex were studied by 1D and 2D 1H NMR spectroscopy. The reversible pressure denaturation experiments in the pressure range from 1 bar to 5 kbar were carried out at pH 2.0 and 10 degrees C. The cold denaturation was carried out at 3 kbar, where the protein solution can be cooled down to -25 degrees C without freezing. Including heat denaturation experiments, the experimental data obtained allowed us to construct the pressure--temperature phase diagram of RNase A. The experimental results suggest the possibility that all three denaturation processes (cold, heat, and pressure) lead to non-cooperative unfolding. The appearance of a new histidine resonance in the cold-denatured and pressure-denatured RNase A spectra, compared to the absence of this resonance in the heat-denatured state, indicates that the pressure-denatured and cold-denatured states may contain partially folded structures that are similar to that of the early folding intermediate found in the temperature-jump experiment reported by Blum et al. [Blum, A. D., et al. (1978) J. Mol. Biol. 118, 305]. A hydrogen-exchange experiment was performed to confirm the presence of partially folded structures in the pressure-denatured state. Stable hydrogen-bonded structures protecting the backbone amide hydrogens from solvent exchange were observed in the pressure-denatured state. These experimental results suggest that the pressure-denatured RNase A displays the characteristics of a the inhibitor 3'-UMP show that the RNase A-inhibitor complex is more stable than RNase without the inhibitor.

Effects of daurisoline on cytosolic free calcium in fetal rat cerebral cells

Cytosolic free Ca2+ ([Ca2+]i) was measured in dissociated cerebral cells isolated from fetal rats with the fluorescent indicater fura-2. Increase in [Ca2+]i occurred rapidly following exposure of the cells to 50 mmol/L KCl, 10(-7) mol/L Bay K 8644 or 200 mumol/L glutamate (Glu). [Ca2+]i elevated by K(+)-depolarization was attenuated by pretreatment with 10(-7), 10(-6) mol/L daurisoline (Dau). The response of [Ca2+]i to K(+)-depolarization did not change when 10(-8) mol/L Dau was added. When 10(-8)-10(-6) mol/L Dau was added to the cell suspensions prior to exposure to Glu, the Glu-stimulated rises in [Ca2+]i were reduced significantly. However, Dau (10(-6), 10(-7) and 10(-8) mol/L) did not alter the response to Bay K 8644. These results indicate that Dau can inhibit the increase of [Ca2+]i in fetal rat cerebral cells induced by certain Ca2+ agonists, especially Glu, suggesting that this drug may have a protective effect against cerebral cellular injury.

High pressure 2H-NMR study of the order and dynamics of selectively deuterated dipalmitoyl phosphatidylcholine in multilamellar aqueous dispersions

High pressure 2H multipulse NMR techniques were used to investigate the effects of pressure on the structure and dynamics of selectively deuterated 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) multilamellar aqueous dispersions. The samples were deuterated on both chains at positions 2, 9, or 13. The deuterium lineshapes, the spin-lattice relaxation times, T1, and the spin-spin relaxation times, T2, were measured as a function of pressure from 1 bar to 5 kbar at 50 degrees C for the three deuterated DPPC samples. This pressure range permitted us to explore the phase behavior of DPPC from the liquid-crystalline (LC) phase through various gel phases such as the Gel I (P beta), Gel II (L beta), Gel III, Gel X, and the interdigitated, Gel i, gel phase. Pressure had an ordering effect on all chain segments both in the LC phase and various high pressure gel phases as indicated by the increase in SCD bond order parameter and the first moment, M1, with pressure. Compared with the adjacent gel phases, the Gel i phase had the highest order. Also, in all gel phases the carbon-9 segment of the chains had the most restricted motions in contrast to the LC phase, where the carbon-2 segment was the most restricted. In the LC phase, T1 and T2 values for all segments decreased with pressure, indicative of the fast correlation time regime. Similarly, T1 decreased with pressure in the Gel I and the interdigitated Gel i gel phases but changed to the slow correlation time regime at the Gel i/Gel II phase transition. For T2, which reflects slow motions, the transition to the slow correlation time regime occurred already at LC/Gel I phase transition. Considering the various motions which contribute to relaxation, the behavior of T1 and T2 in the Gel 11 through Gel X phases showing discontinuities and slope changes at the phase transitions was, as expected, quite complex.In addition we found a straight line relationship for T-1 vs. S2D, and T-1 vs. S2CD for the deuterons in the 9 and 13 positions in the LC phase in the pressure range investigated.

A new multipurpose CO2 laser therapy instrument

A new multipurpose CO2 laser therapy instrument has been developed. It is a highly efficient medical instrument. By use of high laser power density to coagulate, evaporate, and cut body tissue on the nidus, the operation can be controlled and has obvious curative effects. Unlike other kinds of CO2 laser therapy instruments, this device has an advanced switching power supply (SPS) and red guiding light system. With an overcurrent protective device, an overvoltage protective device, and a high-voltage shield device, it provides efficiency, stability, reliability, and low loss. The plastic casing does not leak electricity and the film switches are designed for clinical practice convenience. Additionally, the laser power is numerically displayed and can be set prior to the procedure. The distinct visible guiding light of the laser output makes the operation more convenient and accurate. Because of this unique design and properties, it is a leading model in China. The instrument can be widely used for surgery, gynecology, dermatology, and otolaryngology. The radiation therapy of low laser power density has the effect of being antiinflamatory, analgesic, and antipruritic, and promotes cure of the epithelium. Moreover, it is effective to treat all sorts of sprains, scapulohumeral periarthritis, arthritis, sciatica, and surface ulcers.

cDNA cloning and sequence analysis of NIb gene of soybean mosaic virus

cDNA of soybean mosaic virus (Beijing isolate, SMV-BJ) has been synthesized, using viral genomic RNA as a template and random hexanucleotides as primers. Based on the sequences of SMV-BJ coat protein (CP) gene as well as SMV- and WMV-II-related regions, oligonucleotides were made as primers for polymerase chain reaction (PCR). NIb gene of SMV-BJ was amplified by PCR, and cloned into pBluescript SK. The complete sequence was determined. The comparison of NIb genes between SMV-BJ and WMV-II (USA) shows that similarities for nucleotide sequence reach 80.3%; and the deduced amino acid sequence, 91.3%. In consideration of the high identities in between the CP gene and the 3'-non-coding region between them, WMV-II might be considered as a watermelon strain of SMV. Besides, some unexpected sequences were found in the 3'-region of 2 NIb gene clones. Following modification and splicing, a binary vector of NIb gene has been constructed for its expression in higher plant for the purpose of studying the possible replicase-mediated resistance in polyviruses.

One and two dimensional 1H-NMR studies of pressure and tetracaine effects on sonicated phospholipid vesicles

One and two dimensional 1H-NMR experiments have been performed to study the molecular order and dynamics of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) unilamellar vesicles under the influence of high pressure and the local anesthetic, tetracaine (TTC), which can also be considered as a model-charged amphiphile. The TTC molecules have an ordering effect on the headgroups but a disordering effect on the acyl chains, whereas, pressure has an ordering effect on the acyl chains. The results from 2D NOESY experiments on pure DPPC vesicles show that the intensities of NMe3/CH3, NMe3/(CH2)n, and CH3/(CH2)n cross-peaks increase with increasing pressure in the liquid-crystalline phase but decrease with pressure in the gel phase, further suggesting that the appearance of the cross-peaks between the two extremes of the DPPC molecules is due to spin-diffusion. For the DPPC/TTC vesicles, the 2D NOESY experiments confirm that charged TTC molecules are located in the headgroup region of the DPPC bilayers and, in the gel phase, also suggest the formation of an interdigitated gel phase.

Studies on high salt tolerance of transgenic tobacco

With E. coli mtlD gene (encoding mannitol 1-phosphate dehydrogenase) and gutD gene (encoding glucitol 6-phosphate dehydrogenase) cloned, plant expression vector pBIGM had been obtained by inserting mtlD and gutD genes into binary vector pBin438. Tobacco was transformed with A. tumefaciens LBA4404 containing pBIGM. Results of molecular hybridization of transformed plants indicated that mtlD and gutD genes had integrated into the genomic DNA of tobacco plants. Experiments of salt tolerance and analysis of sugar alcohols showed that the accumulation of different sugar alcohols in transgenic tobacco plants had increased salt tolerance of tobacco.

[Treatment of recurrent carcinoma of the uterine cervix]

One hundred thirty seven patients with recurrent carcinoma of the uterine cervix were treated from 1964 through 1985. The primary treatment was surgery in 64 cases and radiation of 73 cases. Treatment consisted of surgery (n = 13) radiotherapy with or without Chinese medicine (n = 92), chemotherapy (n = 26), and chemotherapy plus radiation (n = 6). The mean 5-year survival rate of this series was 40.9%. One patient survived 28 year without tumor. Seven of 13 surgically treated patients were alive and free of disease for 5 to 28 years with an average 5-year survival rate of 53.8%. Thirty recurrent cases following radiotherapy were again treated by radiation, 11 of them (36.7%) were alive for 5 years.

Methylation of cottontail rabbit papillomavirus DNA and tissue-specific expression in transgenic rabbits

Transgenic rabbits carrying multiple copies of CRPV genomic DNA were described previously (Peng et al. (1993) J. Virol. 67, 1698-1701). CRPV DNA was detectable in all tissues of the transgenic rabbits, however, the transcripts of CRPV genes only were found in skin and skin tumors. Tumor development was also restricted to skin. To study the mechanism involving tissue-specific expression of CRPV genes in rabbits, cellular DNAs, isolated from different normal tissues and skin tumors, were digested with the two isoschizomeric restriction endonucleases MspI (methylation resistant) and HpaII (methylation sensitive), respectively, and analyzed by Southern blot. CRPV DNA, especially its upstream regulatory region (URR), was extensively methylated in all normal tissues, but methylation was remarkably reduced in skin tumors. These data suggest that extensive methylation of CRPV genome, especially in the URR, might be a factor in controlling its tissue-specific expression.

Immunocytochemical localization of the alpha 7 subunit of the nicotinic acetylcholine receptor in the rat central nervous system

Previous molecular cloning studies have revealed that alpha-bungarotoxin binding proteins present in the brain are members of the neuronal nicotinic acetylcholine receptor gene family. The alpha 7 subunit is structurally related to the agonist binding subunits present in the central and peripheral nervous systems and, when expressed in Xenopus oocytes, forms functional channels blockable by alpha-bungarotoxin. In the present study, three different monoclonal antibodies raised against the alpha 7 subunit were used to map its distribution throughout the central nervous system of the rat. Immunohistochemical localization revealed that the alpha 7 subunit is expressed in most regions of the brain, being, overall, well correlated with previous "in situ" localization of alpha 7 transcripts and alpha-bungarotoxin autoradiographic binding studies. Particularly strong immunoreactivity was observed in several sensory and motor nuclei of the brainstem as well as the red nucleus. At the cellular level, alpha 7 immunostaining was usually found both in somata and dendrites, whereas axonal and terminal labeling was not observed. The widespread distribution of the alpha 7 subunit polypeptide is consistent with immunoprecipitation data demonstrating that it is a component of the predominant subtype of brain alpha-bungarotoxin-sensitive nicotinic receptors.

Nicotine-induced increase in neuronal nicotinic receptors results from a decrease in the rate of receptor turnover

Chronic nicotine exposure in tobacco smokers or experimental animals is known to cause an increase in brain binding sites for nicotine. It has been proposed that this is an adaptive response of neurons to accumulation of chronically desensitized receptors. Acetylcholine receptors of the same (alpha 4)2(beta 2)3 subunit composition as the predominant subtype of brain nicotinic receptors with high affinity for nicotine have been expressed in Xenopus oocytes and in a permanently transfected fibroblast cell line. Chronic exposure of these cells to nicotine or another agonist is shown to result in an increase in receptor amount, indicating that nicotine-induced up-regulation reflects properties of the alpha 4 beta 2 receptor protein, rather than being an adaptive response unique to the neurons in which these receptors are normally expressed. The nicotine concentration dependence, time course, and extent of receptor up-regulation are similar to those reported for receptors in brain. Up-regulation does not appear to require ion flow through the ion channel, because it is also caused by mecamylamine, which blocks the ion channel, and because after prolonged exposure to nicotine most receptors become permanently unable to open their channels in response to nicotine binding. The noncompetitive antagonist mecamylamine blocks open channels more effectively, and so it is more effective at blocking channels in the presence of nicotine. Mecamylamine and nicotine are also synergistic in causing receptor up-regulation. Ligands that cause up-regulation appear to induce a conformation of the receptor that is removed from the surface and degraded more slowly.

[Cloning of T7 lysozyme gene and construction of the vector for transgenic plants resistant to bacterial infection]

DNA were extracted from bacteriophage T7 and digested partially with Ava II. T7 lysozyme gene was obtained by PCR. DNA sequence analysis showed that the nucleotide sequence of T7 lysozyme gene was 99.5% homologous with the reported sequence and its deduced amino acid sequence was the same as reported. DNA fragment encoding the signal peptide of the pathogenesis-related protein 1b(PR-1b) from tobacco and cecropin (Shiva-I) gene cloned in pUC19 were modified by PCR. The PR-1b signal peptide gene was fused respectively to the 5' terminals of T7 lysozyme gene and expression vector, so that T7 lysozyme gene and Shiva-I gene could express simultaneously in transgenic plants and the two gene products could be secreted to extracellular space.

Physostigmine and galanthamine: probes for a novel binding site on the alpha 4 beta 2 subtype of neuronal nicotinic acetylcholine receptors stably expressed in fibroblast cells

In the present study, we demonstrated that the chicken alpha 4 beta 2 neuronal nicotinic receptor stably expressed in transfected mouse fibroblasts (M10 cells) can be activated via the acetylcholine-binding site or via a site that is distinct from that for acetylcholine and recognizes physostigmine and galanthamine as agonists. In outside-out patches excised from dexamethasone-induced M10 cells, (+)-anatoxin-a, physostigmine and galanthamine (each at 1 microM) activated single channels with conductances of 18 and 30 pS. Dihydro-beta-erythroidine (1-30 nM), but not the nicotinic receptor-specific monoclonal antibody FK1, reduced the frequency of channels activated by anatoxin (1 microM). On the other hand, the frequency of channel activity induced by physostigmine (1 microM) was unaffected by dihydro-beta-erythroidine and was markedly decreased by FK1. In uninduced M10 cells and in dexamethasone-treated untransfected fibroblasts, we observed that physostigmine, galanthamine and nicotinic agonists did not evoke whole-cell or single-channel currents. Also, neither [3H]L-nicotine nor FK1 was able to bind to uninduced M10 cells. In dexamethasone-induced M10 cells, the nicotinic agonists acetylcholine, anatoxin, 1,1-dimethyl-4-phenylpiperazinium, (-)-nicotine, and cytisine (each at 100 microM) activated whole-cell currents that showed a marked inward rectification and were sensitive to blockade by dihydro-beta-erythroidine (100 nM). However, neither galanthamine nor physostigmine could evoke whole-cell currents in cells that were responsive to nicotinic agonists. Other effects of physostigmine and galanthamine on the nicotinic receptor that outweight the agonist properties of these compounds could account for their inability to evoke whole-cell currents.

High-pressure NMR study of the dissociation of Arc repressor

Different denatured states of Arc repressor were characterized by one-dimensional and two-dimensional NMR and by fluorescence spectroscopy. Increasing pressure promoted sequential changes in the structure of Arc repressor: from the native dimer through a predissociated state to a denatured molten globule monomer. A compact state (molten globule) of Arc repressor was obtained in the dissociation of Arc repressor by pressure whereas high temperature and urea induced dissociation and unfolding to less structured conformations. The NMR spectra of the monomer under pressure (up to 5.0 kbar) are typical of a molten globule, and they are considerably different from those of the native dimer and the thermally or chemically denatured monomer. The substantial line broadening and overlap of many resonances in the NMR spectra at high pressures indicate that there is interconversion between a number of different conformations of the molten globule at an intermediate exchange rate. The two-dimensional NOE spectra show that the pressure-denatured monomer retains substantial secondary structure. The presence of NOEs in the beta-sheet region in the dissociated state suggests that the intersubunit beta-sheet (residues 6-14) in the native-dimer is replaced by an intramonomer beta-sheet. Changes in 2D NMR spectra prior to dissociation indicate the existence of a predissociated state that may represent an intermediate in the folding and subunit association pathway of Arc repressor.

Human alpha 7 acetylcholine receptor: cloning of the alpha 7 subunit from the SH-SY5Y cell line and determination of pharmacological properties of native receptors and functional alpha 7 homomers expressed in Xenopus oocytes

The alpha-bungarotoxin-binding acetylcholine receptors from the human neuroblastoma cell line SH-SY5Y were found to cross-react with some monoclonal antibodies to alpha 7 subunits of nicotinic acetylcholine receptors from chicken brain. The human alpha 7 subunit cDNA from SH-SY5Y was cloned, revealing 94% amino acid sequence identity to rat alpha 7 subunits and 92% identity to chicken alpha 7 subunits. Native human alpha 7 receptors showed affinities for some ligands similar to those previously observed with native chicken alpha 7 receptors, but for other ligands there were large species-specific differences in binding affinity. These results paralleled properties of alpha 7 homomers expressed in Xenopus oocytes. Human alpha 7 homomers exhibited rapidly desensitizing, inwardly rectifying, agonist-induced, cation currents that triggered Ca(2+)-sensitive Cl- channels in the oocytes. A change in efficacy from partial agonist for chicken alpha 7 homomers to full agonist for human alpha 7 homomers was exhibited by 1,1-dimethyl-4-phenylpiperazinium. This result reveals a large species-specific pharmacological difference, despite small differences in alpha 7 sequences. This is important for understanding the effects of these drugs in humans and for identifying amino acids that may contribute to the acetylcholine binding site, for analysis by in vitro mutagenesis. These results also characterize properties of native alpha 7 receptors and alpha 7 homomers that will provide criteria for functional properties expected of structural subunits, when these can be identified, cloned, and coexpressed with alpha 7 subunits.

Thyrotrophin-dependent desensitization by Chinese hamster ovary cells that express the recombinant human thyrotrophin receptor

To determine whether thyrotrophin (TSH)-induced desensitization requires a thyroid-specific factor(s), the human TSH (hTSH) receptor was expressed in Chinese hamster ovary cells. The first incubation of the cells with TSH decreased the subsequent response of adenosine 3',5'-cyclic monophosphate to freshly added TSH in the second incubation. This homologous desensitization was observed as early as after 3 h of the first incubation. The lowest dose of TSH that elicited desensitization was 0.1 nmol/l. The desensitization was not overcome by adding higher doses of TSH in the second incubation. A 125I-labelled TSH-binding study revealed a decrease in the number of high-affinity binding sites but not in that of low-affinity binding sites. The data suggest that TSH-induced desensitization in hTSH receptor-transfected cells is caused, at least in part, by a decrease in the number of TSH receptors on the cell surface. The evidence demonstrates, contrary to an earlier report, that a thyroid-specific factor(s) is not required for hTSH receptor desensitization.

Pharmacological characterization of alpha-bungarotoxin-sensitive acetylcholine receptors immunoisolated from chick retina: contrasting properties of alpha 7 and alpha 8 subunit-containing subtypes

At least three subtypes of alpha-bungarotoxin-sensitive acetylcholine receptors (alpha Bgt-sensitive AChRs) exist in chick brain and retina. All may contain previously unknown structural subunits. One subtype contains alpha 7 subunits. Another contains alpha 8 subunits. A third contains both alpha 7 and alpha 8 subunits. In this article, we describe, for the first time, the pharmacological characterization of alpha 7 AChRs and alpha 8 AChRs immunoisolated from chick retina. Pharmacologically, the alpha 8 AChRs exhibit two classes of binding sites, the high affinity of which have higher affinity for most cholinergic ligands than do alpha 7 AChRs. These differences are most accentuated for ACh (approximately 5400-fold), decamethonium (approximately 1400-fold), 1,1,-dimethyl-4 phenylpiperazinium (approximately 200-fold), atropine (approximately 200-fold), nicotine (approximately 100-fold), and tetramethylammonium (approximately 100-fold). The alpha 8 AChR low affinity sites exhibit affinities that are similar but not identical to that of alpha 7 AChRs. Many of the pharmacological differences between the alpha 7 AChRs and alpha 8 AChRs can be attributed to the limited differences between the amino acid sequences of the N-terminal region of the alpha 7 and alpha 8 subunits because expressed alpha 7 homomers and alpha 8 homomers also exhibit these characteristic differences.

Reporter epitopes: a novel approach to examine transmembrane topology of integral membrane proteins applied to the alpha 1 subunit of the nicotinic acetylcholine receptor

The development of a novel immunological method called the "reporter epitope" technique to probe the transmembrane topology of integral membrane proteins is described. Using this method, synthetic oligonucleotides encoding epitopes (reporter epitopes) for well characterized monoclonal antibodies (reporter mAbs) were inserted at various locations within the human acetylcholine receptor (AChR) alpha 1 subunit cDNA. The engineered subunits were then expressed along with Torpedo beta 1, gamma, and delta subunits in Xenopus oocytes, and the transmembrane location of the site of insertion was determined by the binding of the 125I-labeled reporter mAbs to whole oocytes. Control reporter epitope insertions at alpha 347 exhibited the expected cytoplasmic location. Reporter epitopes inserted at alpha 429 are located on the extracellular surface. Reporter epitopes that are 16-48 amino acids long do not disrupt assembly or function of hybrid AChRs when inserted near the carboxy terminus (at alpha 429) or in the large cytoplasmic domain (at alpha 347). However, because two reporter epitopes inserted at alpha 157 obliterated subunit assembly and a third reporter epitope when tolerated at this position was inaccessible from the extracellular surface and only marginally accessible after detergent solubilization of the AChRs, a definitive transmembrane location for this region was not possible. Nonetheless, the use of this approach has been successfully demonstrated, and it may be generally applicable to the study of other integral membrane proteins.

Homomeric and native alpha 7 acetylcholine receptors exhibit remarkably similar but non-identical pharmacological properties, suggesting that the native receptor is a heteromeric protein complex

Sucrose gradient analysis of chick acetylcholine receptor (AChR) alpha 7 subunits expressed in oocytes indicates that they form pharmacologically active homomers of the same size as native alpha 7 AChRs, a size compatible with a complex of five alpha 7 subunits. By immunoisolating the [35S]methionine-labeled alpha 7 subunits we also demonstrate that they do not appear to assemble with endogenous Xenopus AChR subunits. Pharmacological characterization of detergent-solubilized brain alpha 7 AChRs and alpha 7 homomers reveals that they have similar but nonidentical properties. The pharmacological difference is most accentuated for cytisine (approximately 50-fold). Thus, at least in E18 chicken brain, most or all of the native alpha 7 AChRs do not appear to be homomeric.

Effects of amino acid substitutions on the pressure denaturation of staphylococcal nuclease as monitored by fluorescence and nuclear magnetic resonance spectroscopy

In the present study we have used high hydrostatic pressure coupled with either time-resolved and steady-state fluorescence or NMR spectroscopy in order to investigate the effects of amino acid substitutions on the high-pressure denaturation properties of staphylococcal nuclease. This protein has been shown previously to be structurally heterogeneous in its native state. On the NMR time scale, four distinct interconverting conformational forms arise from the population of both cis and trans Xaa-Pro peptide bonds (His46-Pro47 and Lys116-Pro117) [Evans et al. (1989) Biochemistry 28, 362; Loh et al. (1991) in Techniques in Protein Chemistry II, pp 275-282, Academic Press, New York]. Mutations in the protein sequence have been shown to change the distribution among the various forms [Alexandrescu et al. (1989) Biochemistry 28, 204; Alexandrescu et al. (1990) Biochemistry 29, 4516]. Time-resolved fluorescence on a series of mutants with altered equilibria for cis/trans isomerism about the 116-117 peptide bond did not reveal any simple relationship between the position of the cis/trans equilibrium in the folded state and the heterogeneity of the fluorescence decay. However, the specific dynamic properties of each mutant, as revealed by time-resolved fluorescence, do appear to be correlated with their partial molar volume changes of denaturation. A striking finding is that mutation of either (or both) of the prolines that exhibits structural heterogeneity to glycine greatly alters the stability of the protein to pressure. These mutations also result in decreased chain mobility as assessed by time-resolved fluorescence. It appears that packing defects, which allow for peptide bond cis/trans heterogeneity in the wild-type protein, are removed by the Pro-->Gly substitutions.

Papillomas and carcinomas in transgenic rabbits carrying EJ-ras DNA and cottontail rabbit papillomavirus DNA

Two transgenic rabbits (TRI and TRIII) that carried cottontail rabbit papillomavirus (CRPV) DNA alone were identified; another (TRII) carried both CRPV DNA and EJ-ras. TRI and TRIII developed extensive skin papillomas at about 1 month of age, and transcripts of CRPV DNA were detectable only in skin and/or papillomas. TRII developed extensive squamous carcinomas of the skin at a very early age. Transcription of both CRPV DNA and EJ-ras was found in the skin cancers. Thus, the tissue specificity of CRPV DNA expression in transgenic rabbits was the same as in virion-infected animals. The expression of EJ-ras could be dependent on the expression of certain CRPV genes and may be a critical cofactor of CRPV DNA in the progression of carcinomas.

Molten-globule conformation of Arc repressor monomers determined by high-pressure 1H NMR spectroscopy

The conformation of the pressure-dissociated monomer of Arc repressor was characterized by 1H NMR spectroscopy. The NMR spectra of the monomer under pressure (up to 5.0 kbar; 1 bar = 100 kPa) are typical of a molten globule and they are considerably different from those of the native dimer and thermally denatured monomer. The two-dimensional nuclear Overhauser effect spectra suggest that the pressure-induced molten globule retains some secondary structure. The presence of nuclear Overhauser effects in the beta-sheet region in the dissociated state suggests that the intermonomer beta-sheet (residues 8-14) in the native dimer is replaced by an intramonomer beta-sheet. Changes in one-dimensional and two-dimensional NMR spectra prior to pressure dissociation were found and suggest the existence of a "predissociated" state.

[Localization of E(wa) in Drosophila melanogaster using rearrangement]

The white-apricot (wa) allele differs from the wild type white gene by the presence of the retrovirus-like transposable element copia within the transcription unit. The activity of wa is reduced in trans by a semidominant mutation in the gene Enhancer-of white-apricot (E(wa)). The map position of E(wa) is refined by analyzing recombination among three genes: px, E(wa) and sp. The recombinational distance between E(wa) and sp is 0.2 cM, which places E(wa) at 2-106.8. To localize E(wa) cytologically, four Y; 2 translocations, one 1;2 translocation and three 2R deficiency stocks were crossed to the suitable E(wa) stocks and the wa sons were scored for intensity of pigment and the speck at the axis of wings. The E(wa) was placed in the distal portion of 60B. The one E(wa) mutation and two sp mutations derived from our gamma-ray mutagenesis were used for examination of polytene chromosome. The former was a revertant which has a cytologically visible insertion of material from an unknown source at 60B5-13, most likely in the 60B8-9. It is likely that this insertion is within the E(wa) gene. The latter shows breakpoint at 60C1-2, where is likely the location of the sp gene. Combining the data of both cytological localization and recombinational mapping, the E(wa) was localized at 60B5-13, most likely in the 60B8-9, the left of sp but very close to it.

Life security of the elderly: rural population control

"This article will examine the life security among the elderly in rural China and its impact on the population control in those areas." Data are from a fertility survey conducted in five rural villages in 1990.

Geometry for contouring by electronic speckle pattern interferometry based on shifting illumination beams

When the method of contouring an object surface by electronic speckle pattern interferometry is based on shifting the illumination beams, the shifted phase of the interference speckle pattern has a new relationship with the depth of the test surface. Therefore the contour interval as well as the fringe sensitivity of this method has new forms. The geometry of such a situation, which differs from that of either the method of two-wavelength contouring or the method of contouring by tilting the test object is presented. The requirements on the experimental conditions for this method are also presented. Experimental results are in agreement with these analyses.

Contouring by electronic speckle pattern interferometry with quadruple-beam illumination

We present a new arrangement for contouring by electronic speckle pattern interferometry with four illumination beams, thereby making it unnecessary to move anything during the.

High-pressure 31P NMR study of dipalmitoylphosphatidylcholine bilayers

High-pressure 31P NMR was used for the first time to investigate the effects of pressure on the structure and dynamics of the phosphocholine headgroup in pure 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) multilamellar aqueous dispersions and in DPPC bilayers containing the positively charged form of the local anesthetic tetracaine (TTC). The 31P chemical shift anisotropies, delta sigma, and the 31P spin-lattice relaxation times, T1, were measured as a function of pressure from 1 bar to 5 kbar at 50 degrees C for both pure DPPC and DPPC/TTC bilayers. This pressure range permitted us to explore the rich phase behavior of DPPC from the liquid-crystalline (LC) phase through various gel phases such as gel I (P beta'), gel II (L beta'), gel III, gel IV, gel X, and the interdigitated, Gi, gel phase. For pure DPPC bilayers, pressure had an ordering effect on the phospholipid headgroup within the same phase and induced an interdigitated Gi gel phase which was formed between the gel I (P beta') and gel II (L beta') phases. The 31P spin-lattice relaxation time measurements showed that the main phase transition (LC to gel I) was accompanied by the transition between the fast and slow correlation time regimes. Axially symmetric 31P NMR lineshapes were observed at pressures up to approximately 3 kbar but changed to characteristic axially asymmetric rigid lattice lineshapes at higher pressures (3.1-5.1 kbar).(ABSTRACT TRUNCATED AT 250 WORDS)

Cystitis, urolithiasis and cystic calculi in ageing guineapigs

Nineteen cases of cystitis were diagnosed at necropsy and/or by histology in a group of 170 (96 females, 74 males) guineapigs (11.2%). Seventeen of the 19 cases (89.4%) were females. The mean age of guineapigs with cystitis was 34.7 months, which was higher than the mean age of 24 months of the 170 members of the study group. In addition, 6 cases of urolithiasis and cystic calculi in 5 females and one male were also found in the 170 guineapigs (3.5%). The mean age of the 6 cases was 30 months, which was also higher than the mean age of the 170 animals. The study suggests that aged female guineapigs were much more predisposed to cystitis and urolithiasis or cystic calculi than male and young guineapigs. The cause may be related to infection with Escherichia coli and Staphylococcus sp, cystic calculi, diabetes mellitus and female guineapig urogenital anatomy and function.

Effect of cage population density on plasma corticosterone and peripheral lymphocyte populations of laboratory mice

The effect of different population densities of mice per cage on plasma corticosterone, peripheral lymphocytes and specific lymphocyte subpopulations was investigated. The animals were housed in groups of 2, 4 or 8 mice per cage and the blood samples were taken from each animal of these groups on days one, 7 and 14. A significant elevation (P less than 0.05) in plasma corticosterone concentration was observed in the group of 8 mice per cage on days one and 7 as compared with those of 2 or 4 mice per cage. The number of peripheral lymphocytes was significantly decreased in the groups of 2 (P less than 0.01) and 8 (P less than 0.05) mice per cage as compared with the group of 4 mice per cage on day one. A significantly decreased number of lymphocytes (P less than 0.01) in the group of 8 mice per cage continued to day 7. There were no significant differences in specific lymphocyte subpopulations observed among these groups. The results of this study suggest that a population density of 4 mice per cage induced minimal stress compared to that induced by the population densities of 2 or 8 mice per cage. Since stress is known to induce alteration in a variety of biological functions, the population density of mice per cage should be considered in the interpretation of research data.