Tyrosine kinase inhibitors, emodin and its derivative repress HER-2/neu-induced cellular transformation and metastasis-associated properties

We have previously shown that emodin suppresses tyrosine kinase activity of HER-2/neu-encoded p185neu receptor tyrosine kinase. In this study, we examine the relationship between the chemical structure and the activity of emodin and nine derivatives, and identified that one methyl, one hydroxy, and one carbonyl functional groups are critical for the biological activities of emodin. We also found that one of the derivatives 10-(4-acetamidobenzylidene)-9-anthrone (DK-V-47) is more effective than emodin in repressing the tyrosine phosphorylation of p185neu and in inhibiting the proliferation and transformation of HER-2/neu-overexpressing human breast cancer cells. Using mutation-activated HER-2/neu transformed 3T3 cells, we also investigated whether emodin and DK-V-47 can inhibit malignant transformation induced solely by the HER-2/neu oncogene. We found that DK-V-47 is more potent than emodin in suppressing transformation phenotypes of activated HER-2/neu transformed 3T3 cells including anchorage-dependent and -independent growth, metastasis-associated properties. These results clearly indicate that the inhibition of p185neu tyrosine kinase by both emodin and DK-V-47 is capable of suppressing the HER-2/neu associated transformed phenotypes including the ability to induce metastatic potential. Our results also support the chemotherapeutic implications of the use of either emodin or DK-V-47 to target HER-2/neu-overexpressing cancer cells.

Low and high frequency electroacupuncture at Hoku elicits a distinct mechanism to activate sympathetic nervous system in anesthetized rats

To address the effect of electroacupuncture (Ea) on autonomic nerve activity, the responses of rhythmic micturition contraction (RMC), urine excretion (UE), blood pressure (BP), renal sympathetic nerve activity (RNA) and pelvic parasympathetic nerve activity (PNA) to Ea were investigated in urethane-anesthetized rats. The acupoint Hoku (Li-4) was tested with two different stimulation frequencies (2 Hz and 20 Hz). Elongation of the RMC cycle and an increase in UE associated with the elevation of BP and RNA was elicited during Ea at Hoku. However, the pressor response induced by low frequency Ea (LFEa) was different from that by high frequency Ea (HFEa), i.e. a tonic effect was elicited by LFEa, while a phasic one was induced by HFEa. These results imply that: (1) Ea at Hoku may selectively activate the sympathetic, but not the parasympathetic nervous system, (2) Ea at Hoku with a different stimulation frequency may elicit a distinct mechanism to activate the sympathetic nervous system and (3) Ea at Hoku may ameliorate the hyperactive bladder in clinical therapy.

The BRC repeats in BRCA2 are critical for RAD51 binding and resistance to methyl methanesulfonate treatment

The BRCA2 gene was identified based on its involvement in familial breast cancer. The analysis of its sequence predicts that the gene encodes a protein with 3,418 amino acids but provides very few clues pointing to its biological function. In an attempt to address this question, specific antibodies were prepared that identified the gene product of BRCA2 as a 390-kDa nuclear protein. Furthermore, direct binding of human RAD51 to each of the four single 30-amino acid BRC repeats located at the 5' portion of exon 11 of BRCA2 was demonstrated. Such an interaction is significant, as BRCA2 and RAD51 can be reciprocally coimmunoprecipitated by each of the individual, specific antibodies and form complexes in vivo. Inferring from the function of RAD51 in DNA repair, human pancreatic cancer cells, Capan-1, expressing truncated BRCA2 were shown to be hypersensitive to methyl methanesulfonate (MMS) treatment. Exogenous expression of wild-type BRCA2, but not BRC-deleted mutants, in Capan-1 cells confers resistance to MMS treatment. These results suggest that the interaction between the BRC repeats of BRCA2 and RAD51 is critical for cellular response to DNA damage caused by MMS.

Characterization of the antiplatelet effects of (2S)-5-methoxy-6-methylflavan-7-ol from Draconis Resina

(2S)-5-methoxy-6-methylflavan-7-ol (MMF) was purified from Draconis Resina and its in vitro effects on various aspects of platelet reactivity were examined. Results indicated that MMF dose dependently inhibited aggregation of washed rabbit platelets induced by collagen, arachidonic acid, ADP, U46619 or platelet-activating factor (PAF), with IC50) values of 17.2, 49.8, 179.8, 109.6, and 189.2 microM, respectively. Concomitantly, MMF also dose dependently suppressed ATP release by platelets activated by these stimulants. The increase in intracellular free calcium ([Ca2+]i), elicited by these activating agents, was inhibited by MMF as reflected by fura-2 fluorescence measurements. However, MMF had no effects on the cyclic AMP level of platelets. In addition, MMF inhibited the arachidonic acid-induced thromboxane B2 and prostaglandin D2 formation in intact platelet suspensions or homogenized platelet lysates. This study provided evidence that MMF is an antiplatelet agent whose activity is likely related to cyclooxygenase inhibition and suppression of [Ca2+]i increase.

Anti-tumor effects of d-dicentrine from the root of Lindera megaphylla

d-Dicentrine, a naturally occurring aporphine type isoquinoline alkaloid, isolated from the root of Lindera megaphylla Hemsl. (Lauraceae), was evaluated for its potential anti-cancer activity. We found d-dicentrine significantly inhibited the growth of human hepatoma cell line HuH-7 by delaying its doubling time in tissue culture. An in vitro colony forming assay showed that d-dicentrine decreased the colony formation efficiency in both hepatoma cell lines, HuH-7 and MS-G2, used in our study. Biosyntheses of the macromolecules DNA and RNA were also strongly inhibited. An MTT assay in 21 tumor cell lines also revealed that d-dicentrine was most cytotoxic to esophageal carcinoma HCE-6, lymphoma cell lines Molt-4 and CESS, leukemia cell lines HL60 and K562, and hepatoma cell line MS-G2. An in vitro tumor growing assay in the Severe Combined immunodeficiency (SCID) mice showed that intraperitoneal injection of d-dicentrine at the dose of 100 micrograms twice a week for 4 weeks significantly inhibited the tumor incidence of leukemia cell line K562 in SCID mice. All these data indicated that d-dicentrine has potential anti-tumor applications.

Identification of a novel cytoplasmic protein that specifically binds to nuclear localization signal motifs

Active transport of proteins into the nucleus is mediated by interaction between the classical nuclear localization signals (NLSs) of the targeted proteins and the NLS receptor (importin) complex. This nuclear transport system is highly regulated and conserved in eukaryotes and is essential for cell survival. Using a fragment of BRCA1 containing the two NLS motifs as a bait for yeast two-hybrid screening, we have isolated four clones, one of which is importin alpha. Here we characterize one of the other clones identified, BRAP2, which is a novel gene and expressed as a 2-kilobase mRNA in human mammary epithelial cells and some but not all tissues of mice. The isolated full-length cDNA encodes a novel protein containing 600 amino acid residues with pI 6.04. Characteristic motifs of C2H2 zinc fingers and leucine heptad repeats are present in the middle and C-terminal regions of the protein, respectively. BRAP2 also shares significant homology with a hypothetical protein from yeast Saccharomyces cerevisiae, especially in the zinc finger region. Antibodies prepared against the C-terminal region of BRAP2 fused to glutathione S-transferase specifically recognize a cellular protein with a molecular size of 68 kDa, consistent with the size of the in vitro translated protein. Cellular BRAP2 is mainly cytoplasmic and binds to the NLS motifs of BRCA1 with similar specificity to that of importin alpha in both two-hybrid assays in yeast and glutathione S-transferase pull-down assays in vitro. Other motifs such as the SV40 large T antigen NLS motif and the bipartite NLS motif found in mitosin are also recognized by BRAP2. Similarly, the yeast homolog of BRAP2 also binds to these NLS motifs in vitro. These results imply that BRAP2 may function as a cytoplasmic retention protein and play a role in regulating transport of nuclear proteins.

Acupuncture utilization in Taiwan

BACKGROUND

The objective of this study was to examine the prevalence of acupuncture utilization in Taiwan by people over 20 years of age.

METHODS

Stratified cluster sampling was used to randomly select 20 villages and neighborhoods (townships), a total of 8,280 people, from northern, central, southern and eastern Taiwan. A structured questionnaire was used to collect information during home visits. A total of 5,805 questionnaires were valid for use in the study.

RESULTS

The complete rate of home visits was 70.1%; 73.2% of those interviewed recognized acupuncture as one of the common therapeutic methods used in traditional Chinese medicine, whereas only 12.4% had received acupuncture treatment. Typical interviewees who had received acupuncture treatment were generally ethnic from southern Fukien and aged from 30-39 years; 58.3% of the 716 interviewees had received acupuncture treatment from licensed practitioners, while the remainder were treated by non-licensed practitioners.

CONCLUSIONS

The response rate to the questionnaire was high (70.1%). However, the percentage of people who had received acupuncture treatment was only 12.4%, while many people (73.2%) were familiar with it. Approximately 40% of those who received acupuncture treatment did so from non-licensed practitioners. This may reveal either a lack of awareness by the public or a lack of public protection of health and safety.

Magnolol inhibits Mac-1 (CD11b/CD18)-dependent neutrophil adhesion: relationship with its antioxidant effect

Magnolol, a phenolic compound isolated from a Chinese herbal drug, Magnolia officinalis, has been shown to protect rat heart from ischemia/reperfusion injury. Neutrophil adhesion plays a crucial process during this inflammatory response. To evaluate whether magnolol prevents ischemia/reperfusion injury by inhibiting neutrophil adhesion, we determined whether magnolol can inhibit adhesion of phorbol-12-myristate-13-acetate (PMA)-activated human neutrophils to a fibrinogen-coated surface in a dose-dependent manner. Using flow cytometric analysis, we observed that magnolol pretreatment (10 min at 37 degrees C) diminished PMA (100 ng/ml)-induced Mac-1 upregulation. PMA also induced rapid intracellular accumulation of superoxide (O2-.) and hydrogen peroxide (H2O2) in neutrophils; magnolol pretreatment attenuated the accumulation of these two substances. Inhibition of reactive oxygen species by superoxide dismutase and/or catalase, which decompose O2-. and H2O2, respectively, also abolished Mac-1 upregulation and neutrophil adhesion. We conclude that magnolol inhibits neutrophil adhesion and that this can account for its anti-ischemia/reperfusion injury effect. We propose that the inhibitory effect of magnolol on neutrophil adhesion to the extracellular matrix is mediated, at least in part, by inhibition of the accumulation of reactive oxygen species, which in turn suppresses the upregulation of Mac-1 that is essential for neutrophil adhesion.

Cloning of porcine neuron growth inhibitory factor (metallothionein III) cDNA and expression of the gene in Saccharomyces cerevisiae

Growth inhibitory factor (GIF), a member of the metallothionein (MT) family, is also known as MTIII. This protein distinguishes itself from other MT isoforms by exerting an inhibitory effect on cortical neuron growth instead of metal ion buffering. In this work, we cloned MTIII genes from a porcine brain cDNA library. Two species of clones were isolated that vary with respect to one nt in the coding sequence. This discrepancy results in the translation of two MTIII primary structures having a different amino acid at residue 46. Herein, both MTIII cDNAs were constructed into an expression vector and transformed into yeast cells, respectively. The yeast carrying either MTIII gene displayed a similar metal tolerance when cultured in a medium containing metal. The resistance to metal toxicity was attributed to the expression of MTIII gene which was confirmed by RNA and protein analyses. The characteristics of the protein stability, metal binding affinity and ultraviolet absorption spectrum of the yeast produced MTIII are also compared with those of MTII. The comparison reveals that both MTs have similar physical characteristics. Moreover, circular dichroism spectrum of Cd saturated MTIII was analyzed as well. Typical Cys-Cd bands for MTII appear in the spectrum, indicating similar metal-thiol interactions for MTIII to those for other MT isoforms.

Suppression of extracellular signals and cell proliferation through EGF receptor binding by (-)-epigallocatechin gallate in human A431 epidermoid carcinoma cells

Tea polyphenols are known to inhibit a wide variety of enzymatic activities associated with cell proliferation and tumor progression. The molecular mechanisms of antiproliferation are remained to be elucidated. In this study, we investigated the effects of the major tea polyphenol (-)-epigallocatechin gallate (EGCG) on the proliferation of human epidermoid carcinoma cell line, A431. Using a [3H]thymidine incorporation assay, EGCG could significantly inhibit the DNA synthesis of A431 cells. In vitro assay, EGCG strongly inhibited the protein tyrosine kinase (PTK) activities of EGF-R, PDGF-R, and FGF-R, and exhibited an IC50 value of 0.5-1 microgram/ml. But EGCG scarcely inhibited the protein kinase activities of pp60v-src, PKC, and PKA (IC50 > 10 micrograms/ml). In an in vivo assay, EGCG could reduce the autophosphorylation level of EGF-R by EGF. Phosphoamino acid analysis of the EGF-R revealed that EGCG inhibited the EGF-stimulated increase in phosphotyrosine level in A431 cells. In addition, we showed that EGCG blocked EGF binding to its receptor. The results of further studies suggested that the inhibition of proliferation and suppression of the EGF signaling by EGCG might mainly mediate dose-dependent blocking of ligand binding to its receptor, and subsequently through inhibition of EGF-R kinase activity.

The hepatoprotective and therapeutic effects of propolis ethanol extract on chronic alcohol-induced liver injuries

Propolis designates a mixture of gums, resins and balms, of viscous consistency, which are gathered on certain parts (buds and bark, mainly) of vegetables (especially coniferous trees) by honeybees. They bring this back to the hive, where it is modified and mixed with other substances (essentially their own wax and salivary secretions). In this study, the hepatoprotective and therapeutic effects of propolis ethanol extract on chronic alcohol-induced liver injuries were investigated in rats. 3.125 ml of 99.5% alcohol was added to animal's daily diet for four weeks to induce chronic alcohol liver injuries. After sacrifice, serum transaminases (GOT, GPT), triacylglyceride and hepatic triacylglyceride (HTG) concentration were assayed to observe liver injuries induced by chronic alcohol abuse. In addition, the phenomenon of alcohol induced fatty liver were also observed by histopathological changes. Different doses of propolis ethanol extract were p.o. administered three times per day for three days, after four weeks' alcohol administration. It was found that 10 mg/kg of propolis ethanol extract significantly decreased the elevations of serum GOT, GPT, TG and HTG. In histopathological examination, 30 mg/kg of propolis ethanol extract also remarkably decreased the hepatocellular fatty degeneration, apparent as vacuolization, induced by chronic alcohol abuse.

Attenuated response of renal mechanoreceptors to volume expansion in chronically hypoxic rats

Multifiber renal afferent nerve activity responds to volume expansion in sea level rats but not in chronically hypoxic (high altitude) rats. We performed single-unit recordings of renal afferent nerve activity to characterize renal sensory receptors and their responses to volume expansion in these animals. Hypoxia was induced by placing Wistar rats in an altitude chamber (380 Torr, 5,500 m) for 4 wk. Spontaneously firing renal R2 chemoreceptor and arterial, ureteropelvic, and venous mechanoreceptors were identified. The basal activity of each receptor was similar among these rats. In response to specific stimulus, the increasing impulse of R2 chemoreceptor was similar between two groups of rats, but the increasing activity of each mechanoreceptor was less in hypoxic rats. When challenged with saline load, R2 chemoreceptor activity decreased, but all mechanoreceptors activated in all rats. Despite similar increases of arterial, renal ureteropelvic, and venous pressure during saline load, the increasing activity of each mechanoreceptor was significantly less in hypoxic rats. These results indicated chronic hypoxia attenuates the sensitivity of renal mechanoreceptors in response to the stimulation of saline load.

Hemodynamic effects of acute tetrandrine and terlipressin administration on portal hypertensive rats

The purpose of this study was to investigate the therapeutic effects of tetrandrine and terlipressin, alone or in combination, on anesthetized portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation in Sprague-Dawley rats. Each portal hypertensive rat received one of three regimens: vehicle plus terlipressin, tetrandrine (.50 mg.kg-1.min-1) [corrected] plus terlipressin, or tetrandrine (.75 mg.kg-1.min-1) [corrected] plus terlipressin. Terlipressin dosage was 0.025 mg.kg-1.min-1 [corrected] infused for 3 min. Infusion of vehicle followed by terlipressin induced significant reduction of portal venous pressure (PVP, -24.3 +/- 1.5%) and prominent elevation of mean arterial pressure (MAP, 73.3 +/- 4.6%) as well as total peripheral resistance (TPR, 133 +/- 8%) from baseline, and there was a cardiodepressant response (cardiac index, CI, -30.6 +/- 3.8%; heart rate, HR, -10.4 +/- 2.1%). Infusion of tetrandrine (.50 mg.kg-1.min-1) [corrected] induced significant reduction of PVP (-7.2 +/- 0.9%), MAP (-12.5 +/- 1.6%), and TPR (-14.3 +/- 4.2%) from baseline. Infusions of tetrandrine followed by terlipressin induced significant reduction of PVP (-14.2 +/- 2.4%) but an increase in MAP (22.6 +/- 2.7%) and TPR (71.1 +/- 10.5%). Infusion of tetrandrine (.75 mg.kg-1.min-1) [corrected] induced significant reduction of PVP (-9.9 +/- 0.8%). MAP (-19.2 +/- 2.1%), and TPR (-24.1 +/- 2.1%) from baseline. Infusions of tetrandrine followed by terlipressin induced significant reduction of PVP (-14.0 +/- 1.1%) but an increase in MAP (14.0 +/- 2.7%) and TPR (75.2 +/- 5.2%). Compared with vehicle followed by terlipressin, tetrandrine significantly attenuated systemic pressor (MAP and TPR elevation), cardiodepressant (CI reduction) as well as portal hypotensive (PVP reduction) effects of terlipressin. Our results suggest that tetrandrine and terlipressin, alone or in combination, induced portal hypotensive effects in portal hypertensive rats. Combined tetrandrine and terlipressin administration ameliorated systemic pressor and cardiodepressant effects of terlipressin, but it also attenuated the latter's portal hypotensive effects.

6-Methoxy-N-methyl-1,2,3,4-tetrahydro-beta-carboline from Evodiae Fructus

A receptor binding assay directed separation has led to the identification of a minor alkaloid 6-methoxy- N-methyl-1,2, 3,4-tetrahydro-beta-carboline (1) from the Chinese herbal drug Evodiae Fructus [EF, the dried, unripe fruit of Evodia rutaecarpa Look. f. et Thomas (Rutaceae)]. The structure of compound 1 was elucidated by means of spectroscopic methods and a comparison with synthetic materials. Compound 1 interacted with 5-HT (1A) and 5-HT (2) receptors with a moderate K (i) value of 78 and 1.2 microM, respectively. Compound 1 is found in EF and the genus Evodiae for the first time.

Suppression of extracellular signals and cell proliferation through EGF receptor binding by (-)-epigallocatechin gallate in human A431 epidermoid carcinoma cells

Tea polyphenols are known to inhibit a wide variety of enzymatic activities associated with cell proliferation and tumor progression. The molecular mechanisms of antiproliferation are remained to be elucidated. In this study, we investigated the effects of the major tea polyphenol (-)-epigallocatechin gallate (EGCG) on the proliferation of human epidermoid carcinoma cell line, A431. Using a [3H]thymidine incorporation assay, EGCG could significantly inhibit the DNA synthesis of A431 cells. In vitro assay, EGCG strongly inhibited the protein tyrosine kinase (PTK) activities of EGF-R, PDGF-R, and FGF-R, and exhibited an IC50 value of 0.5-1 microgram/ml. But EGCG scarcely inhibited the protein kinase activities of pp60v-src, PKC, and PKA (IC50 > 10 micrograms/ml). In an in vivo assay, EGCG could reduce the autophosphorylation level of EGF-R by EGF. Phosphoamino acid analysis of the EGF-R revealed that EGCG inhibited the EGF-stimulated increase in phosphotyrosine level in A431 cells. In addition, we showed that EGCG blocked EGF binding to its receptor. The results of further studies suggested that the inhibition of proliferation and suppression of the EGF signaling by EGCG might mainly mediate dose-dependent blocking of ligand binding to its receptor, and subsequently through inhibition of EGF-R kinase activity.

Identification of cellular TSG101 protein in multiple human breast cancer cell lines

tsg101 was identified as a tumor susceptibility gene by homozygous functional inactivation of allelic loci in mouse 3T3 fibroblasts. The human homologue was mapped at chromosome 11p15.1-2 and found to have intragenic deletion in 7 of 15 breast cancer specimens. To further confirm the relevance of defects in this gene to breast cancer, antibodies specific for the putative gene product were prepared and used to identify cellular TSG101 protein. The antibodies recognized a 46-kDa protein in human retinoblastoma WERI-27 cells labeled with [35S]methionine. This protein was not detected with preimmune sera. In cell fractionation studies, the 46-kDa protein cofractionating with glutathione S-transferase was found mainly in the cytoplasm. Similarly, when cells were immunostained with anti-TSG101 antibodies, fluorescence was localized in the cytoplasm of most of the cells. A full-size 46-kDa TSG101 protein was detected in a panel of 10 breast cancer cell lines and 2 normal breast epithelial cell lines with the same antibodies. Consistently, the full-length TSG101 mRNA was also detected in these breast cells using reverse transcription-PCR. These results indicate that homozygous intragenic deletion of TSG101 is rare in breast cancer cells.

Hemodynamic effects of chronic tetrandrine treatment in Sprague-Dawley rats

Tetrandrine is a calcium channel antagonist with reported anti-hypertensive effect. The present study aimed to investigate the hemodynamic effects of chronic tetrandrine treatment on normotensive Sprague-Dawley rats. Animals were allocated into one of the two groups: tetrandrine group and vehicle group. Tetrandrine (20 mg/kg) or vehicle was administered by gavage every 12 hours for consecutive 8 days. After 8 days of tetrandrine treatment, systemic hemodynamics and organ blood flows were measured on the next morning after an overnight fast, using radioactive microsphere method. Mean arterial pressure (96 +/- 2 vs. 118 +/- 4 mmHg) and systemic vascular resistance (254 +/- 35 vs. 369 +/- 5 dyn.sec.cm5 x 10(3)/100 g body wt) were significantly decreased in the tetrandine group as compared to the vehicle group. The cardiac-index (35.2 +/- 2.7 vs. 25.5 +/- 0.8 mL/min/100 g body wt) was increased in the tetrandrine group. The portal venous pressure, portal tributary blood flow, portal territory vascular resistance, renal blood flow, renal vascular resistance, heart rate and body weight were similar between the two groups. In conclusion, long-term treatment of tetrandrine reduced mean arterial pressure and systemic vascular resistance but did not change splanchnic or renal hemodynamics in normal rats.

Myocardial mechanics and titin in experimental insulin-resistant rats

We investigated the intrinsic cardiac mechanics of myocardium and changes in titin in insulin-resistant rats. Microsonometry and micromanometry were used to evaluate the maximal elastance (Emax) and myocardial stiffness constant (Km) of the left ventricle, in addition to the traditional systolic and diastolic cardiac function, with an isolated working heart preparation. Thirty 150 g Wistar rats were divided into three groups of 10. Group A was fed rat chow, while groups B and C were fed a 66% fructose diet for 7-8 months. Group C also received clonidine. Group B rats developed insulin resistance, as well as elevated plasma glucose and blood pressure. Group C rats also had insulin resistance and elevated plasma glucose, but not higher blood pressure. Group B rats had decreased Emax, decreased peak-dp/dt, prolonged Tau and increased Km compared to normal control rats. Group C rats, which mimicked the clinical condition of diabetic cardiomyopathy, maintained normal global left ventricular function as revealed by cardiac output, peak + dp/dt, peak-dp/dt and Tau of relaxation. However, they had a lower Emax slope (355 +/- 51 vs 535 +/- 56 mmHg.mm than group A rats, p < 0.05) and increased Km (81.6 +/- 9.9 vs 25.5 +/- 4.8 in group A, p < 0.001), even though the extent of elevation of plasma glucose was only mild (71.3 +/- 2.0 to 108.9 +/- 4.4 mg/dl, p < 0.001). Their left ventricular mass, myocyte size, interstitial fibrosis and vascular picture did not change. However, the content of myocardial titin decreased significantly (intensity ratio of titin/actin was 0.23 +/- 0.01 and 0.29 +/- 0.02 in group C and group A rats respectively, p < 0.05). These findings suggest that changes in titin play a role in the change in myocardial functional characteristics and may be one of the causes of diabetic cardiomyopathy.

Designing better adaptive sampling algorithms for ECG Holter systems

Let psi be any adaptive sampling algorithm that can run in real time on a tapeless multichannel electrocardiogram (ECG) Holter system. Simple methods which can significantly improve psi's fidelity are described and their results are compared in this paper. It is shown that by adding some simple tests to psi, the signals reconstructed by psi can be improved as much as 5.45 dB. It is also shown that under the same data rate, a good data compressor with slowly sampled input ECG is preferable to a bad data compressor with highly sampled input ECG.

[A study on the risk factors of Binswanger's leukoencephalopathy (BE)]

A matched case-control study (1:1) was carried out among 122 hospitalized patients with Binswanger's leukoencephalopathy to explore the possible risk factors of BE. Data collected were processed with conditional logistic regression analysis. Individual logistic analysis showed that family history of vascular dementia, history of hypertension, diabetes, coronary heart disease, transient cerebral ischemic attacks (TIAs), cerebral ischemia, cerebral hemorrhage, renal disfunction, alcohol intake smoking were risk factors while healthy life style played protective effect. Body weight index, average family income, education level and type A behavior scores did not show close relations with BE. Multiple regression analysis showed that hypertension, TIAs, coronary heart disease, diabetes and family history of vascular dementia were independent risk factors.

The interactions of paeoniflorin and veratrine on isolated rat atria

In this study, we attempted to identify the interactions and mechanisms between veratrine and paeoniflorin on isolated rat atria. Paeoniflorin alone showed no effect on the rat atria. Veratrine increased the atrial contraction and induced arrhythmia at 1 x 10(-5) g/ml. Veratrine could directly induce contraction and elicit tetanic contraction at 1 x 10(-4) g/ml in the left atria with or without electric stimulation. Paeoniflorin (4.8 x 10(-6) to 4.8 x 10(-3) g/ml), verapamil (2.2 x 10(-6) g/ml), tetrodotoxin (TTX) (3.2 x 10(-8) g/ml) and quinidine (7.5 x 10(-6) g/ml) inhibited the increase of contraction and delayed the onset of contraction induced by veratrine (1 x 10(-5) g/ml). The inhibitory effect of paeoniflorin combined with verapamil on the contraction induced by veratrine was more potent than that of paeoniflorin or verapamil alone. However, the inhibitory effect of paeoniflorin was not potentiated by TTX or quinidine. From the above results, the contraction evoked by veratrine in the rat atria may be concluded to be caused by the stimulation of Na(+)- and Ca(2+)-ion channels. The inhibition of paeoniflorin on the contraction induced by veratrine may primarily be related to the blockade of Ca2+ channels.

Renal function of substance P in rats chronically exposed to hypoxia

BACKGROUND

We studied the renal action of substance P (SP) in rats chronically exposed to hypoxia (high altitude, HA), compared to control rats kept at sea level (SL).

METHODS

Hypoxia was induced by placing female Wistar rats (182-225 g) in an altitude chamber (5500 m) 15 h.d-1 for 4 weeks.

RESULTS

Intrarenal arterial infusion of substance P (60 ng.kg-1. h-1) increased the excretion of urine, sodium in both groups of rats, however, the excretion of kallikrein (KK) and the glomerular filtration rate (GFR) were not significantly altered. After aprotinin (10,000 kiu.kg-1. min-1) treatment, kallikrein was depleted, and substance P lost its diuretic action. Spantide, an SP antagonist (6000 ng.kg-1. h-1, I.V.) decreased urine, and urinary excretion of sodium and potassium in SL rats, but not in HA rats. Acute renal denervated diuresis in SL rats was not modified after Spantide administration. Finally, it was found that both SP and SP antagonist did not significantly change the renal parameters in either group of rats after chronic renal denervation.

CONCLUSION

We made the following conclusions: a) endogenous renal action of SP was suggested in SL but not in HA rats; b) the renal action of SP might be through KK release, although urinary KK did not increase after SP administration; and c) SP action is renal nerve dependent in both groups of rats.

Cytotoxic constituents from the stems of Diospyros maritima

One novel coumaric acid ester of lupeol, dioslupecin A (1), three naphthoquinones, 8'-hydroxyisodiospyrin (2), isodiospyrin (3), and plumbagin (4), three triterpenes, lupeol, lupenone and taraxerone, and four sterols, beta-sitosterol, stigmasterol, stigmast-4-en-3-one and ergosta-4,6,8(14),22-tetraen-3-one were isolated from the n-hexane extract of the stems of Diospyros maritima Blume. The structural determination of 1 was based on 1D and 2D NMR spectra (including 1H-1H COSY, 1H-13C COSY, and HMBC). All compounds were evaluated for in vitro cytotoxicity in 4 cancer cell lines. Compound 2 showed similar cytotoxicity against hepatoma (HEPA-3B, ED50 = 1.72 micrograms/ml), nasopharynx carcinoma (KB, ED50 = 1.85 micrograms/ml), colon carcinoma (COLO-205, ED50 = 2.24 micrograms/ml) and cervical carcinoma (HELA, ED50 = 1.92 micrograms/ml). Compounds 3 and 4 exhibited strong cytotoxicity against HEPA-3B, KB, COLO-205 and HELA (ED50 = 0.25, 1.81, 0.13 and 0.27 micrograms/ml for 3; ED50 = 0.87, 3.27, 0.56 and 0.35 micrograms/ml for 4, respectively.

Haemodynamic effects of chronic tetrandrine treatment in portal hypertensive rats

Tetrandrine is a calcium channel antagonist with reported antihypertensive effect. However, the potential role of tetrandrine as a therapeutic agent in portal hypertension has yet to be explored. The present study aimed to investigate the haemodynamic effects of chronic tetrandrine treatment on portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation in Sprague-Dawley rats. Animals were allocated into one of two groups: a tetrandrine group and a vehicle group. Tetrandrine (20 mg/kg) or vehicle was administered by gavage every 12 h for 8 consecutive days, starting 1 day before ligation and continuing thereafter. After 8 days of tetrandrine treatment, systemic haemodynamics, organ blood flow and the degree of portal-systemic shunting were measured after an overnight fast. The portal venous pressure and protal tributary blood flow were significantly decreased, while portal territory as well as hepto-collateral vascular resistance significantly increased in the tetrandrine group compared with the vehicle group. The cardiac index was increased, while systemic vascular resistance was decreased, the the tetrandrine group. Mean arterial pressure, heart rate, portal-systemic shunting and bodyweight were similar between the two groups. Renal blood flow was decreased in the tetrandrine group. In conclusion, long-term treatment of tetrandrine reduced portal venous pressure and alleviated splanchnic hyperaemina in portal hypertensive rats without affecting the portal-systemic shunting.