Studies on protective mechanisms of four components of green tea polyphenols against lipid peroxidation in synaptosomes

The comparison of the protective effects of four components of "green tea polyphenols' (GTP) - (-)-epigallocatechin gallate, EGCG; (-)-epicatechin gallate, ECG; (-)epigallocatechin, EGC; and (-)epicatechin, EC - against iron-induced lipid peroxidation in synaptosomes showed that: (1) the inhibitory effects of those compounds on TBA reactive materials from lipid peroxidation decreased in the order of EGCG > ECG > EGC > EC; (2) the scavenging effects of those compounds on lipid free radicals produced by lipid peroxidation could be classified as follows: ECG > EGCG > EC > EGC. Furthermore, we investigated the iron-chelating activity and the free radical scavenging activity of those compounds as their protective mechanisms against lipid peroxidation in synaptosomes. As for the iron-chelating activity, the ratio of EGC, EGCG, ECG or EC to iron(III) was 3:2, 2:1, 2:1 and 3:1, respectively. The hydroxyl radical (HO) scavenging activity of those compounds was investigated in a photolysis of the H2O2 system. It was found that their ability to scavenge hydroxyl radicals decreased in the order of ECG > EC > EGCG >> EGC. It was also found that they could scavenge lipid free radicals in the lecithin/lipoxidase system and their scavenging activity was classified as follows: ECG > EGCG >> EGC > EC. Moreover, we found that their antioxidant active positions were different from each other and the stability of the semiquinone free radicals produced by those compounds in NaOH solution decreased in the order of EGCG > ECG >> EC. The results indicated that the ability of those compounds to protect synaptosomes from the damage of lipid peroxidation initiated by Fe2+/Fe3+ was dependent not only on their iron-chelating activity and free-radical scavenging activity, but also on the stability of their semiquinone free radicals.

Oxytocin is required for nursing but is not essential for parturition or reproductive behavior

Oxytocin, a neurohypophyseal hormone, has been traditionally considered essential for mammalian reproduction. In addition to uterine contractions during labor and milk ejection during nursing, oxytocin has been implicated in anterior pituitary function, paracrine effects in the testis and ovary and the neural control of maternal and sexual behaviors. To determine the essential role(s) of oxytocin in mammalian reproductive function, mice deficient in oxytocin have been generated using embryonic stem cell technology. A deletion of exon 1 encoding the oxytocin peptide was generated in embryonic stem cells at a high frequency and was successfully transmitted in the germ line. Southern blot analysis of genomic DNA from homozygote offspring and in situ hybridization with an exonic probe 3' of the deletion failed to detect any oxytocin or neurophysin sequences, respectively, confirming that the mutation was a null mutation. Mice lacking oxytocin are both viable and fertile. Males do not have any reproductive behavioral or functional defects in the absence of oxytocin. Similarly, females lacking oxytocin have no obvious deficits in fertility or reproduction, including gestation and parturition. However, although oxytocin-deficient females demonstrate normal maternal behavior, all offspring die shortly after birth because of the dam's inability to nurse. Postpartum injections of oxytocin to the oxytocin deficient mothers restore milk ejection and rescue the offspring. Thus, despite the multiple reproductive activities that have been attributed to oxytocin, oxytocin plays an essential role only in milk ejection in the mouse.

Tissue-specific binding of radiolabeled activin A by activin receptors and follistatin in postimplantation rat and mouse embryos

Activin affects the growth and differentiation of many cultured cell types, including rat anterior pituitary cells and gonadal and neuronal cell lines. Endogenous activins regulate mesoderm induction, body axis formation, and organogenisis in the developing embryo. The messenger RNAs encoding inhibin/activin subunits, follistatin (an activin-binding protein), and activin type II receptors (ActRII and IIB) are expressed in various cell types and tissues of the embryonic rat and mouse. Follistatin-deficient mice have numerous embryonic defects, including shiny taut skin, allowing relatively easy identification by the later stages of embryogenesis. ActRII-deficient mice, on the other hand, show limited developmental defects, with some (22%) embryonic day 18.5 (E18.5) ActRII-deficient embryos showing various skeletal and facial abnormalities. The present study was undertaken to identify the target tissues for biologically active activin A and assess the significance of its association with ActRII and follistatin in developing rat and mouse embryos. Fresh-frozen, slide-mounted, rat (E13 to E19) and mouse (E18.5) embryo sections were incubated with 125I-labeled recombinant human activin A. Nonspecific binding was evaluated by competition with an excess of cold activin A. As determined by image analysis, the highest levels of activin A binding were observed throughout the brain, spinal cord, and trigeminal and spinal ganglia at all ages. Lower levels of binding were found in the dermis of the skin starting on E15. Follistatin-deficient mice demonstrated similar patterns and levels of activin A binding in the neural tissues compared to wild-type controls, but binding was absent in the skin. In ActRII-deficient mice, activin A binding was completely absent in neural tissues, but was similar to wild-type control levels in the dermal layer of the skin. The data indicate that activin A binds to specific tissues of mouse and rat embryos and that binding is dependent upon the presence of ActRII in the central and peripheral nervous system and on follistatin in the skin.

Role of Val509 in time-dependent inhibition of human prostaglandin H synthase-2 cyclooxygenase activity by isoform-selective agents

Prostaglandin H synthase (PGHS), a key enzyme in prostanoid biosynthesis, exists as two isoforms. PGHS-1 is considered a basal enzyme; PGHS-2 is associated with inflammation and cell proliferation. A number of highly selective inhibitors for PGHS-2 cyclooxygenase activity are known. Inhibition by these agents involves an initial reversible binding, followed by a time-dependent transition to a much higher affinity enzyme-inhibitor complex, making these agents potent and poorly reversible PGHS-2 inhibitors. To investigate the PGHS-2 structural features that influence the time-dependent action of the selective inhibitors, we have constructed a three-dimensional model of human PGHS-2 by homologous modeling. Examination of the PGHS-2 model identified Val509 as a cyclooxygenase active site residue, that was not conserved in PGHS-1. Recombinant human PGHS-2 with Val509 mutated to either Ile (the corresponding residue in PGHS-1), Ala, Glu, or Lys was expressed by transient transfection of COS-1 cells to evaluate the effects of the mutations on cyclooxygenase activity and on inhibition by four agents reported to be selective for PGHS-2 (NS398, nimesulide, DuP697, and SC58125). All the recombinant proteins were of the expected mass. The mutants exhibited 45-210% of wild-type cyclooxygenase activity, with Km values for arachidonate of 2.1-7.6 microM (wild-type PGHS-2, 3.8 microM), indicating that changes in position 509 had modest effects on cyclooxygenase catalysis. Each of the agents inhibited wild-type PGHS-2 in a time-dependent fashion, and all but nimesulide did the same for the V509A mutant. In contrast, the V509E and V509I PGHS-2 mutants, like recombinant human PGHS-1, did not show time-dependent inhibition with any of the agents, and the V509K mutant responded in a time-dependent manner only to DuP697. Reversible inhibition was still observed with Val509 mutants that did not show time-dependent inhibition. Thus, the side chain structure at position 509 markedly influenced the ability of PGHS-2 to undergo the time-dependent transition without removing inhibitor or substrate binding. These results indicate that Val509 in PGHS-2 has a major role in the structural transition that underlies time-dependent inhibition by the isoform-selective agents.

Effect of verapamil on Ca2+ influx and CVB3-RNA replication in cultured neonatal rat heart cells infected with CVB3

The effect of verapamil on Ca2+ influx across the myocardial plasma membrane and coxsackie virus B3 (CVB3) -RNA replication in cultured neonatal rat heart cells infected with CVB3 was investigated. It was found that the Ca2+ influx could be inhibited significantly (P < 0.01) by verapamil (1 mumol/L) after infection of heart cells for 48 h. However, when the cultured heart cells infected with CVB3 and treated with verapamil (1 mumol/L and 10 nmol/L) at the same time for 48 h, the amounts of CVB3-RNA in myocytes were significantly higher than that in infected control group (P < 0.05). These phenomena suggest that the increase of Ca2+ influx of cultured heart cells infected with CVB3 could be inhibited by some calcium antagonists, e.g. verapamil at the early stage. On the other hand, verapamil might accelerate viral replication in myocardium. Thus, although verapamil could be beneficial for decreasing the secondary Ca2+ damages and improve the myocardial electric activity, it isn't a sensible choice for therapy in early stage of virus infection with cardiac symptoms.

A single point mutation in epsilon-COP results in temperature-sensitive, lethal defects in membrane transport in a Chinese hamster ovary cell mutant

At the nonpermissive temperature of 39.5 degrees C, the Chinese hamster ovary cell conditionally lethal, temperature-sensitive (ts) mutant ldlF exhibits the following defects: rapid degradation of low density lipoprotein receptors, disruption of ER-through Golgi transport, and disintegration of the Golgi apparatus. All of these are corrected by transfection with an expression vector for wild-type epsilon-COP, a subunit of coatomers (Guo, Q., Vasile, E., and Krieger, M. (1994) J. Cell Biol. 125, 1213-1224). We now report the identification in ldlF cells of a point mutation in the epsilon-COP gene, Glu251 to Lys251, which prevents the corresponding cDNA from correcting the defects in transfected ldlF cells and the immunochemical analysis of the synthesis, structure, and stability of epsilon-COP. At the permissive temperature (34 degrees C), the steady state level of ts-epsilon-COP in ldlF cells was about half that of epsilon-COP in wild-type Chinese hamster ovary cells and the isoelectric point of ts-epsilon-COP was 0.14 pH units higher than that of the wild-type protein. The stability but not the biosynthesis of ts-epsilon-COP was temperature-sensitive (t1/2 > 6 h at 34 degrees C and approximately 1-2 h at 39.5 degrees C), and this accounts for the virtual absence of detectable ts-epsilon-COP protein in ldlF cells after incubation at 39.5 degrees C for > 6h. The steady state levels in ldlF cells of another coatomer subunit, beta-COP, and the peripheral Golgi protein ldlCp were not temperature-sensitive. Thus, a mutation in epsilon-COP that causes instability at 39.5 degrees C is responsible for all of the temperature-sensitive defects in ldlF cells, and the stability of beta-COP is not linked directly to that of epsilon-COP. ldlF cells should be useful for the future analysis of the structure and function of epsilon-COP, the assembly of COPs into coatomers, and the participation of coatomers in intracellular membrane transport.

Marked alteration of proteoglycan metabolism in cholesterol-enriched human arterial smooth muscle cells

To elucidate the correlation between vascular cholesterol metabolism and proteoglycan (PrGl) biosynthesis, we investigated PrGl synthesis in human aortic smooth muscle cells (SMCs) after cholesterol enrichment with cationized low-density lipoproteins (LDL). Compared with normal SMCs, total PrGl synthesis by cholesterol-enriched cells decreased 2.4-fold (11874 +/- 530 d.p.m. per 10(5) cells compared with 4890 +/- 385 d.p.m. per 10(5) cells). This was the net result of a 6.9-fold reduction in medium PrGl (11000 +/- 490 d.p.m. per 10(5) cells compared with 1580 +/- 246 d.p.m. per 10(5) cells) and a 3.8-fold increase in cellular PrGl over controls (874 +/- 27 d.p.m. per 10(5) cells compared with 3310 +/- 193 d.p.m. per 10(5) cells). Prior incubation of SMCs with native LDL had no effect on PrGl synthesis by these cells. The decrease in PrGl synthesis in cholesterol-enriched cells correlated with a 90% and 20% reduction in the steady-state level of mRNA for biglycan and decorin respectively, and a virtual elimination of the steady-state level of mRNA for versican over controls. Despite the down-regulation of PrGl synthesis, cholesterol-loaded cells produced a 2-fold increase in a PrGl subfraction with high affinity for LDL. Compared with the corresponding PrGl subfraction from normal cells, that from the cholesterol-enriched cells exhibited increased charge density and a higher molecular mass and contained relatively larger proportions of chondroitin 6-sulphate and dermatan sulphate. These results show that PrGl metabolism is dramatically altered in cholesterol-enriched human SMCs.

Studies of Qingyangshen (II): modulatory effect of co-treatment with qingyangshen and diphenylhydantoin sodium on rat hippocampal c-fos expression during seizures

We have reported that, after KA treatment in rats, there was first a significant increase in hippocampal c-fos expression during acute seizures and then a long-term inhibition in hippocampal c-fos expression during chronic seizures. In this experiment, we examined the modulatory effect of Qingyangshen (QYS), a traditional Chinese medicine with antiepileptic property, and diphenylhydantoin sodium (DPH) on hippocampal c-fos expression during seizures. We found that after intraperitoneal injection of QYS + DPH (15 mg/kg and 50 mg/kg respectively, q.o.d. x 6), the peak level of hippocampal c-fos mRNA induction during KA-induced acute seizures was reduced by 56.27%; while the inhibition of hippocampal c-fos expression during KA-induced chronic seizures was disinhibited to control level. It is suggested that the inhibitory effect of QYS + DPH on KA-induced seizures, chronic seizures in particular, may have much to do with its modulatory effect on hippocampal c-fos expression.

Effect of hemimethylation and methylation of adenine on the structure and stability of model DNA duplexes

Enzymatic methylation of adenine underlies a variety of biological regulatory mechanisms in Escherichia coli. We present here structural and thermodynamic characterization of a non-self-complementary DNA decamer duplex containing the dam sequence 5'-GATC in the unmethylated, hemimethylated (both forms), and methylated states. Differential scanning calorimetry measurements show that the free energies for adenine methylation of the decamer duplex are +1.1 and +2.0 kcal/mol for hemimethylation, respectively, and +3.3 kcal/mol for full methylation. In all cases, a large unfavorable enthalpy change is partially compensated by a favorable entropy term. CD spectroscopy indicates an overall conformational difference between the unmethylated decamer duplex and its methylated analogs. Reaction with diethyl pyrocarbonate (DEPC), a purine-specific probe sensitive to conformation, is enhanced in the vicinity of the methylation site of the duplex, consistent with loosening of base pairing at this site. Comparison of the scission patterns of these decamer duplexes by the reactive probes methidiumpropyl-EDTA.FeII [MPE.FeII] and CuI(o-phenanthroline)2 [(OP)2CuI] indicates that the methylation site of the decamer duplex represents a site of enhanced reactivity for these agents. On the basis of these thermodynamics and structural features, we suggest that the methylated base pair exists in two different helical states, which require local transient opening of the duplex for interconversion.

Studies of qingyangshen (I): Differential expression of hippocampal c-fos proto-oncogene during kainic acid induced acute and chronic seizures

We previously reported that Qingyangshen (QYS), a traditional Chinese medicine with antiepileptic property, had therapeutic effect on kainic acid (KA) induced experimental seizures (see JTCM 13 (4): 281-286, 1993 for reference). To investigate the mechanisms underlying the anticonvulsant action of QYS, we analyzed the modulatory effect of QYS on rat hippocampal c-fos proto-oncogene expression during KA-induced epileptogenesis in this and the following paper. The expression of hippocampal c-fos gene during KA-induced seizures were examined first. Rats were intraperitoneally injected with kainic acid (KA, 12 mg/kg) and hippocampal c-fos mRNA level was determined by Northern blot analysis during both acute (within one day after KA injection) and chronic (15 days after KA treatment) seizures. A mild increase in hippocampal c-fos mRNA level was observed 30 min after KA injection (being 1.98 +/- 0.70 times of control level), which corresponded temporally to the occurrence of the first limbic seizures. There was an 11.02 +/- 3.33 fold maximal induction of c-fos mRNA at 2 h after KA administration, which remained relatively stable even when behavioral seizures continued to aggravate 4 h after KA treatment. Twelve hours after KA administration, c-fos mRNA in the hippocampus returned to control level when acute seizures began to gradually disappear. In contrast, the induction of hippocampal c-fos mRNA during chronic seizures was inhibited significantly, being reduced by 55.40% compared to control. This suggested that c-fos is in different functional states at acute and chronic stages of epileptogenesis induced by KA.

[Relationship between c-erbB-2 oncoprotein expression and prognosis in salivary gland malignant pleomorphic adenoma]

A monoclonal antibody AB-3 has been used immunohistochemically in a retrospective study of formalin-fixed paraffin embedded tissues of the salivary gland malignant pleomorphic adenomas (MPA). Positive staining was found in 25/60 (41.67%) of MPA. c-erbB-2 oncoprotein expression of the postoperative recurrent MPA group was higher than that of non-recurrent MPA group (P < 0.05). The postoperative 5-year survival rate of MPA with c-erbB-2 expression was considerably lower than that of without expression (P < 0.01). This observation indicates that c-erbB-2 oncoprotein expression may be an useful prognostic indicator in MPA.

Some problems on the measurement of 222Rn concentrations by passive cup method

A passive cup monitor has been constructed by using a 50 mm radius stainless steel hemisphere. The conductive housing has reduced the scatter in track densities. In dwellings with high 220Rn concentrations, it is particularly necessary to measure 222Rn concentration with a monitor having a radon exchange rate less than 0.1 h-1.

Hippocampal quinolinic acid concentrations in epileptogenesis in rats

AIM

To study the changes of hippocampal quinolinic acid (QA) concentrations during acute and chronic seizures induced by ip injection of kainic acid (KA, 12 mg kg-1) in rats.

METHODS

The extraction and measurement of QA in the hippocampus were performed using a gas chromatography-mass spectrometry method.

RESULTS

When acute seizures were fully established 3 h after KA injection, no significant changes of hippocampal QA were found. During chronic seizures observed on d 30 after KA injection, there was even a 55 +/- 8% significant decrease. When neither acute nor chronic seizures were detectable but astroglial proliferation in the hippocampus and secondary neuronal degeneration in extrahippocampal regions became gradually prominent 2 d and 7 d after KA injection, there were 56 +/- 13% and 156 +/- 13% dramatic increases of hippocampal QA concentrations, respectively.

CONCLUSION

The increase of hippocampal QA hardly plays any key role in the initiation of KA-induced seizures but may contribute to astroglial proliferation and neuronal degeneration by activation of N-methyl-D-aspartate receptors.

19F chemical shift imaging technique to measure intracellular pO2 in vivo using perflubron

RATIONALE AND OBJECTIVES

There is a linear relation between the T1 relaxation rate of fluorine-19 (19F) of perfluorochemicals (PFCs) and the partial pressure of the oxygen (pO2) dissolved in the PFC. A line scan technique was used to overcome the significant chemical shift and low signal-to-noise ratio (SNR) of in vivo 19F magnetic resonance imaging. This study was designed to determine whether the line scan technique could detect the effect of oxygen on 19F T1. In addition, its ability to detect changes in intracellular pO2 when the inspired gas was raised from 20% to 100% O2 also was investigated.

METHODS

The T1 relaxation rate of samples of perflubron emulsion diluted from 3.5% to 70% w/v and equilibrated with N2-O2 gas mixtures (pO2 range = 10-450 mm Hg) was measured using the line scan technique. The gas and emulsion pO2 were measured with a blood gas analyzer. The liver T1 relaxation rate was measured in three rabbits given 5 ml/kg perflubron emulsion 4 and 8 days earlier as they breathed room air and then 100% O2. We used a prototype cylindrical coil double-tuned to hydrogen-1 (1H) and 19F and selected a line through the liver. The scanning parameters yielded a voxel size of 20 x 20 x 15.6 mm. Liver and blood samples were obtained postsacrifice for perflubron concentration measurement.

RESULTS

A linear relation between the 19F T1 relaxation rate (1/T1) of the 3.5% w/v emulsion and dissolved pO2 was established with a slope of 0.0033 (sec-1/mm Hg) and a correlation coefficient of .991. As the PFC concentration increased by 1,900%, the slope increased by 21.2%. The 1/T1 for the liver was 0.182 +/- 0.004 sec-1 at baseline. It increased to 0.247 +/- 0.022 sec-1 when rabbits breathed 100% O2 (p = .023), which corresponded to an increase in intracellular pO2 of 19.7 mm Hg. The liver-to-blood PFC concentration ratio was 500:1.

CONCLUSION

In vitro measurements with the line scan technique replicated the established linear dependence of 1/T1 on pO2. In vivo measurements indicated a 20-mm Hg increase in intracellular pO2 of liver phagocytes when the inspired gas was changed from 20% to 100% O2.

[Effect of Astragalus membranaceus on Ca2+ influx and coxsackie virus B3 RNA replication in cultured neonatal rat heart cells]

The effect of Astragalus membranaceus (AM) on Ca2+ influx across the myocardial plasma membrane and coxsackie virus B3(CVB3)-RNA replication in cultured neonatal rat heart cells infected with CVB3 was investigated. It was found that the Ca2+ influx could be inhibited significantly (P < 0.01) by AM after infection of heart cells for 48 h. In addition, when the cultured heart cells infected with CVB3 and treated with AM for 48 h, the Ca2+ influx of infected heart cells also could be inhibited by AM (P < 0.05) and the amounts of CVB3-RNA in myocytes were significantly decreased than that in infected control group (P < 0.001). These phenomena suggested that AM could exert the effects of decreasing the secondary Ca2+ damages, and improving the abnormal myocardial electric activity, and inhibiting replication of CVB3-RNA in myocardium. Thus, it is a rational choice to treat patients with AM in viral myocarditis.

Vector theory of self-focusing of an optical beam in Kerr media

The scalar theory of the self-focusing of an optical beam is not valid for a very narrow beam, and a correct description of the beam behavior requires a vector analysis in this case. A vector nonparaxial theory is developed from the vector Maxwell equations by application of an order-of-magnitude analysis method. For the same input beam, the numerical results of self-focusing from both scalar and vector theories are compared. It is found by the vector theory that a linearly polarized circular input beam becomes elliptical in the selffocusing process.

[Ecological studies on the growth of Pinellia ternata (Thunb.) Breit]

The results show that the following ecological requirements must be met for Pinellia ternata to grow well: warm climate (appropriately 10-27 degrees C), adequate humidity and scattering sunlight. Burning sunlight and high temperature, as well as waterlogging are harmful to its growth.

CNTF or (-)-deprenyl in immature rats: survival of axotomized facial motoneurons and weight loss

The application of ciliary neurotrophic factor (CNTF) to the cut ends of transected facial nerves in newborn rats has been reported to reduce the death of facial motoneurons (FMns) axotomized by the transection. Systemically delivered CNTF has been found to cause cachexia in adult mice. We compared the influence of dosage of CNTF and (-)-deprenyl on FMn death, weight loss, and animal survival in rat pups that underwent facial nerve transection at the 14th postnatal day (P14). CNTF was administered by osmotic mini-pumps connected to tubing ending either intrathecally or extrathecally near the craniocervical junction. CNTF caused weight loss and animal death that was similar to the cachexia reported in mice if administered in amounts of 1.1 microgram/day or greater. At the same doses, intrathecal CNTF was more effective than extrathecal CNTF in inducing the cachexia. (-)-Deprenyl did not alter animal survival or weight gain, even at high doses (10 mg/kg every 2 days). Intrathecal CNTF and intraperitoneal (-)-deprenyl, but not extrathecal CNTF, significantly increased the survival of the axotomized FMns. (-)-Deprenyl administered twice daily at 0.01 mg/kg was considerably more effective than CNTF in increasing FMn survival due to the limitation on CNTF dosage caused by the animal death.