A novel angiogenic factor derived from Aloe vera gel: beta-sitosterol, a plant sterol

Aloe vera gel has a beneficial effect on wound healing. Because angiogenesis is an essential process in wound healing, we hypothesized that Aloe vera gel might contain potent angiogenic compounds. Here we demonstrate that Aloe vera gel and its extracts are angiogenic on the chorioallantoic membrane (CAM) of chick embryo. Out of the three compounds purified from the final fraction of Aloe vera gel, beta-sitosterol showed a potent angiogenic activity in the CAM assay. In the presence of heparin, beta-sitosterol stimulated neovascularization in the mouse Matrigel plug assay and the motility of human umbilical vein endothelial cells in an in vitro wound migration assay. Thus beta-sitosterol is a novel plant-derived angiogenic factor which may have potential pharmaceutical applications for the management of chronic wounds.

A novel angiogenic factor derived from Aloe vera gel: beta-sitosterol, a plant sterol

Aloe vera gel has a beneficial effect on wound healing. Because angiogenesis is an essential process in wound healing, we hypothesized that Aloe vera gel might contain potent angiogenic compounds. Here we demonstrate that Aloe vera gel and its extracts are angiogenic on the chorioallantoic membrane (CAM) of chick embryo. Out of the three compounds purified from the final fraction of Aloe vera gel, beta-sitosterol showed a potent angiogenic activity in the CAM assay. In the presence of heparin, beta-sitosterol stimulated neovascularization in the mouse Matrigel plug assay and the motility of human umbilical vein endothelial cells in an in vitro wound migration assay. Thus beta-sitosterol is a novel plant-derived angiogenic factor which may have potential pharmaceutical applications for the management of chronic wounds.

Effect of 5-methoxypsoralen (5-MOP) on cell apoptosis and cell cycle in human hepatocellular carcinoma cell line

The chemopreventive role of 5-methoxypsoralen (5-MOP) in the human hepatocellular carcinoma (HCC) cell line was investigated by studying the regulation of proliferation and apoptosis in HCC (J5) cells. Morphological analysis, cell viability assay, DNA analysis and cell-cycle analysis suggest that there are at least three modes of the suppressive effects shown by 5-MOP: (a) kills J5 cells directly; (b) induces apoptosis by arresting J5 cells at the G2/M phase in the cell cycle; (c) induces apoptosis through an independent pathway with cell-cycle arrest at 24-72 h of exposure. Further immunoblot analysis demonstrated that inhibition of cyclin B1 by 5-MOP may play an important role in G2/M arrest of J5 cells and provides an additional way to prevent cells from entering the M phase and undergoing apoptosis. 5-MOP therefore appears to exert its anticarcinogenic properties by cytotoxic effect, inducing apoptosis and inhibiting proliferation in the human hepatocellular carcinoma cell line.

Prophylactic lamivudine prevents hepatitis B reactivation in chemotherapy patients

BACKGROUND

Chronic hepatitis B virus carriers receiving chemotherapy develop a high hepatitis B virus reactivation rate (38-53%) with a high mortality (37-60%). Few studies have characterized the efficacy of lamivudine in the treatment of chemotherapy-induced hepatitis B virus reactivation.

AIM

To determine whether lamivudine prophylaxis reduces chemotherapy-induced hepatitis B virus reactivation and mortality.

METHODS

The medical records of all hepatitis B surface antigen-positive patients with malignancy treated with chemotherapy since 1995 at the National University Hospital of Singapore were identified, and divided into those who received lamivudine prophylaxis before chemotherapy (P) and those who did not (NP). The parameters examined included gender, age, malignancy type, steroid usage, number of chemotherapy courses and regimens, follow-up duration and hepatitis B virus status. The outcome measures were hepatitis B virus reactivation (abrupt rise of serum alanine aminotransferase to > 200 IU/L) and reactivation death. Patients with primary hepatoma or liver metastasis were excluded.

RESULTS

Thirty-five patients were identified: 16 in the P group and 19 in the NP group. The baseline characteristics of the two groups were similar. Seven of the 19 patients in the NP group and none of the 16 patients in the P group developed reactivation (36.8% vs. 0%, P=0.009). Six of the seven patients in the NP group who developed reactivation received lamivudine at that time, but five died (mortality, 71.4%), whilst no patient in the P group died from reactivation (P=0.064).

CONCLUSIONS

Prophylactic lamivudine appears to prevent hepatitis B virus reactivation and its associated mortality in patients treated with chemotherapy. This should be confirmed with prospective studies.

Antithrombotic effect of PMC, a potent alpha-tocopherol analogue on platelet plug formation in vivo

Platelet thrombi formation was induced by irradiation of mesenteric venules with filtered light in mice pretreated intravenously with fluorescein sodium. PMC (2, 2, 5, 7, 8-pentamethyl-6-hydroxychromane; 20 microg/g, i.v.) significantly prolonged the latent period of inducing platelet plug formation in mesenteric venules. When fluorescein sodium was given at 10 microg/kg, PMC (20 microg/g) delayed occlusion time by about 1.7-fold. Furthermore, aspirin (250 microg/g) also showed similar activity in delaying the occlusion time. On a molar basis, PMC was about 14-fold more potent than aspirin at delaying the occlusion time. PMC was also effective in reducing the mortality of ADP-induced acute pulmonary thromboembolism in mice when administered intravenously at doses of 5 and 10 microg/g. In addition, intravenous injection of PMC (5 microg/g) significantly prolonged bleeding time by about 1.6-fold compared with normal saline in severed mesenteric arteries of rats. Continuous infusion of PMC (1 microg/g/min) significantly increased the bleeding time by about 1.6-fold and the bleeding time was also significantly prolonged for up to 90 min after cessation of PMC infusion. These results suggest that PMC has an effective antiplatelet effect in vivo and may be a potential therapeutic agent for arterial thrombosis, but must be assessed further for toxicity.

Diagnosing deep vein thrombosis in the lower extremity: correlation of clinical and duplex scan findings

OBJECTIVE

To identify factors that predict a positive duplex scan examination result in patients with suspected deep vein thrombosis of the lower extremity.

DESIGN

Retrospective study.

SETTING

Vascular laboratory in a university teaching hospital.

PATIENTS AND METHODS

The results of 345 lower extremity duplex venous scans performed between August 1994 and November 1998 were reviewed. All patients were in-patients referred from different specialties due to clinical suspicion of lower extremity deep vein thrombosis. Positive duplex scans were correlated with patients' demographic data (sex, age), medical history (history of malignancy, deep vein thrombosis, and pulmonary embolism) and clinical features (leg swelling, venous insufficiency, calf pain, and leg ulcer). Univariate analysis was performed using the Chi squared test.

RESULTS

A total of 345 scans were performed for 313 patients. The mean age was 55 years (range, 19-92 years). Sixty-three patients (49 male, 14 female) had a positive scan, giving a yield of 18.3%. Four factors had a significant association with a positive scan: male sex (P=0.0102), history of malignancy (P=0.0040), history of deep vein thrombosis (P=0.0001), and history of pulmonary embolism (P=0.0265).

CONCLUSIONS

Common presenting clinical features do not predict the result of ultrasonographic investigation for deep vein thrombosis. The chance of having a positive scan is significantly higher in male patients and those with a history of malignancy, deep vein thrombosis, or pulmonary embolism.

Human kinesin superfamily member 4 is dominantly localized in the nuclear matrix and is associated with chromosomes during mitosis

In a previous study, we identified the human counterpart of murine kinesin superfamily member 4 (KIF4), a microtubule-based motor protein [Oh, Hahn, Torrey, Shin, Choi, Lee, Morse and Kim (2000) Biochim. Biophys. Acta 1493, 219-224]. As an initial step to understand the function(s) of human KIF4, its subcellular localization in HeLa cells was examined by using immunocytochemical and subcellular fractionation methods, and it was found that most KIF4 is localized in the nucleus. Since murine KIF4 is known to transport cytoplasmic vesicles, dominant nuclear localization of the human counterpart was somewhat surprising. Subsequent subnuclear fractionation revealed predominant association of KIF4 with the nuclear matrix. These results clearly indicate that human KIF4 is, at least, a nuclear protein. In further confirmation of this conclusion, the hexapeptide PKLRRR (amino acids 773-778) in the molecule was found to function as a nuclear localization signal. During the mitotic phase of the cell cycle, human KIF4 was associated with the chromosomes, suggesting that human KIF4 might be a microtubule-based mitotic motor, with DNA as its cargo.

Polymorphism of the angiotensin-converting enzyme gene in patients with cerebral infarction in Koreans

The relationship between cerebrovascular disease and an insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene is still being debated. The frequency of the DD genotype of the ACE gene was significantly higher in subjects with than those without cerebral infarction in Japan. The aim of the present study was to assess the relationship between ACE gene polymorphism and the development of cerebral infarction in a population from Korea. We examined its possible role as a risk factor in patients with cerebral infarction. The association between ACE gene polymorphism and cerebral infarction was examined in 106 patients with cerebral infarction and 498 controls without cerebral infarction. Frequencies of the genotypes and alleles of the ACE gene were investigated. The ACE genotype was analyzed by the polymerase chain reaction (PCR). The frequency of D allele was 37.7% in patients and 39.1% in controls (chi2 = 0.128, p = 0.720). The frequencies of the genotypes of the ACE gene were II: 39.6%, ID: 45.3%, and DD: 15.1% in patients, and II: 37.1%, ID: 47.6%, and DD: 15.3% in controls (chi2 = 0.127, p = 0.721). There was no significant difference in the frequency of the DD genotype of the ACE gene, and we did not find any association between ACE polymorphism and cerebral infarction. These results indicate that ACE polymorphism is not a risk factor for the development of cerebral infarction in a Korean population.

Autoimmune hepatitis in Singapore: a rare syndrome affecting middle-aged women

BACKGROUND AND AIM

The prevalence of autoimmune hepatitis in Singapore is unknown. Over a period of 7 years, 24 cases were diagnosed in a district general hospital in Singapore (Toa Payoh Hospital) by using the scoring system proposed by the International Autoimmune Hepatitis Group in 1993. The aims of our study were to determine the prevalence of autoimmune hepatitis in Singapore, and to investigate the characteristics and prognosis in the mainly Chinese population.

METHODS

The case records of all 24 patients were reviewed, and the following parameters were recorded: age at presentation, sex, symptoms and signs at presentation, past exposure to hepatotoxic drugs, alcohol intake, blood transfusion laboratory and histological tests used to determine autoimmune hepatitis, response to treatment, complications, and survival.

RESULTS

The mean age of patients was 57 years old. There was a female-male ratio of 11:1. Forty-two percent of the patients were cirrhotic at presentation. The prevalence of autoimmune hepatitis was four per 100 000, with no significant difference between Chinese, Malay and Indian patients (Odds ratio of 0.38 by the chi-squared test). Eighty-nine percent of the patients responded to treatment with the induction of prednisolone, but the relapse rate was 61%. Treatment failure occurred in one patient. The mortality rate during the 7 years of follow up was 21%, and all were caused by complications of cirrhosis. The survival at 5 years was 71%, with a standard error of 0.13.

CONCLUSION

Autoimmune hepatitis in Singapore is mainly a disease in older women. The response to steroid treatment is good, with a 5-year survival rate of 71%.

Lymphoedema care of breast cancer patients in a breast care clinic: a survey of knowledge and health practice

Lymphoedema, an accumulation of protein-rich fluid in interstitial tissue, is a well-recognised life-altering result of breast cancer treatment. With the goal of studying the prevalence and management of lymphoedema after breast cancer therapy, 171 patients were invited to complete a self-administered questionnaire following completion of treatment for breast cancer. The survey revealed that 82.5% of patients knew they were at-risk of developing lymphoedema. However, the level of knowledge about preventive care in lymphoedema was inadequate, with a mean score of 4.07 out of a full mark of 10 (SD=2.35, mode=2). A substantial proportion (45.6%; n=78) of respondents reported that they had experienced lymphoedema and subsequently developed multiple sites of lymphoedema, but only 34.7% (n=26) had been referred for physiotherapy. The study also revealed that patients who had received the combined regimen of mastectomy, lymph node dissection, radiotherapy and chemotherapy were at a higher risk of developing lymphoedema (chi2=6.305, P=0.043). Interestingly, it was found that nurses were the most frequently cited resource for information, but the least consulted professionals for discussion on treatment. It is apparent from our patient survey that there is a lack of knowledge on lymphoedema care amongst breast cancer patients. In order to improve patients' level of knowledge and their awareness of lymphoedema care, the provision for systematic and comprehensive patient education, including management protocols for lymphoedema, needs to be addressed. Education and training, will be essential components of efforts to ensure appropriate care for lymphoedema patients.

Genotyping CagA, VacA subtype, IceA1, and BabA of Helicobacter pylori isolates from Korean patients, and their association with gastroduodenal diseases

The genetic status of cagA, vacA subtype, iceA1, and babA, and the relationship to gastroduodenal diseases were assessed in Helicobacter pylori isolates in Korea. Seventy-six strains of H. pylori were isolated from the antrum and the corpus of 41 adult patients (22 with peptic ulcer and 19 with gastritis). The cagA, iceA1, and babA genes were assessed by polymerase chain reaction and the vacA subtypes were determined by reverse hybridization-line probe assay. The positive rates of 349-bp cagA, 208-bp cagA, iceA1, and babA genes were 97.4%, 96.1%, 84.2%, and 36.1%, respectively. The vacA s1a, s1b, s1c, and s2 variants were detected in 11.8%, 3.9%, 80.4%, and 1.3%, respectively. m1 (78.9%) is more prevalent than m2 (5.3%). The most common vacA genotype was s1c/m1 (61.9%), and 14 isolates (18.4%) contained mixed vacA genotypes from a single biopsy specimen. Twenty-one (60%) of 35 patients were infected with more than two strains of different cagA, iceA1, babA, and vacA genotypes. None of cagA, iceA1, babA, and vacA s1/m1 were associated with peptic ulcer. In conclusion, most H. pylori isolates in Korea carry cagA, iceA1, and vacA s1c/m1 genes, and reside with multiple strains. These genes do not correlate with the peptic ulcer in the Korean patients.

Study on gelatin-containing artificial skin IV: A comparative study on the effect of antibiotic and EGF on cell proliferation during epidermal healing

Gelatin-hyaluronate sponge with and without antibiotic and epidermal growth factor (EGF) were prepared and compared. Four types of sponges were applied on the full-thickness dorsal skin defect of Wistar rat. The effects of antibiotic and EGF in gelatin-hyaluronate sponge on wound healing were investigated by light microscopy and image analyzer at postoperative days of 5, 12 and 21. An immunohistochemical technique, employing PC10, a monoclonal antibody against proliferating cell nuclear antigen (PCNA) was applied to wounded tissue sections. The number of PC10-positive cells was very high for the sponge with EGF at postoperative day 5, then gradually decreased with time. Also we found that antibiotics restrained the cell proliferation during the migratory phase. The sponge with both antibiotic and EGF showed good wound healing performances on the whole for a healing period. The epithelium was regenerated fast with EGF-impregnated sponges at day 5, but each sample had nearly the same length of regenerated epithelium at day 12.

The activation of PI 3-K and PKC zeta in PMA-induced differentiation of HL-60 cells

The human myelocytic leukemia cell line HL-60 is a useful model for the study of cellular differentiation. Phorbol 12-myristate 13-acetate (PMA) induces the monocyte/macrophage-like differentiation of HL-60 cells and results in growth arrest, increasing adherence. In PMA-induced differentiation of HL-60 cells, phosphoinositide 3-kinase (PI 3-K) activity was measured as phosphatidylinositol3P recovery from phosphatidylinositol by in vitro kinase assay. PI 3-K activity was increased in HL-60 cells that were stimulated by 20 nM PMA and the activity was inhibited by pretreatment with 20 microM LY294002, a specific inhibitor of PI 3-K. Members of the protein kinase C (PKC) family have been suggested to be one of the downstream targets of PI 3-K. PKC zeta is one of the atypical PKCs, non-diacylglycerol-responsive PKCs, and the activity was measured by the ability of phosphorylation onto myelin basic protein. PMA also induced the activation of PKC zeta during monocytic differentiation of HL-60 cells, and LY294002-pretreated cells failed to induce PKC zeta activation. The activity of PI 3-K is essential for PKC zeta activation, and LY294002 blocks both monocytic differentiation of HL-60 cells and activation of PKC zeta during PMA-induced cell differentiation. This implies that activated PI 3-K subsequently stimulates the PKC zeta in the process of PMA-induced monocytic differentiation.

Cloning and characterization of a complementary DNA encoding a human epididymis-associated disintegrin and metalloprotease 7 protein

Mammalian spermatozoa interact with the proteins secreted by the epididymis to develop fertility. Transmembrane proteins that possess a disintegrin and metalloprotease (ADAM) domains are shown to be closely related to spermatogenesis and fertilization. Our previous study demonstrated that GP-83, a glycoprotein secreted by the epididymis, was conjugated to mature sperm. In this study, a 2.1-kilobase (kb) GP-83-expressing insert was isolated from a cDNA library of human epididymis by immunoscreening using GP-83-specific antiserum. The 5' end rapid amplification of cDNA ends (RACE) and 3'-RACE of the 2.1-kb insert elucidated two isoforms of GP-83-encoding cDNA sequences, an alpha-form of 3451 base pairs (bp) and beta-form of 2643 bp. Both forms exhibit the same open reading frame of 2262 bp predicting a peptide of 754 amino acid residues. Deduced amino acid sequence revealed signal sequence, prodomain, metalloproteinase, disintegrin, cysteine-rich, epidermal growth factor-like, transmembrane, and cytoplasmic domains. The GP-83-encoding sequence was recognized as human ADAM7 due to significant homology to other ADAM7s. According to the DNA sequences elucidated in the Human Genome Project, h-ADAM7 was located at chromosome 8p22. Ex vivo expression confirmed that h-ADAM7 cDNA did encode GP-83. Northern blot analysis revealed two transcripts of 4 kb and 3 kb in the epididymis, but not in testis or other major tissues. These results indicate that the GP-83-encoding gene is a human epididymis-associated ADAM7 gene (human ADAM7, h-ADAM7) and may be involved in the sperm-egg interaction.

Locating the metal ion in calcium-binding proteins by using cerium(III) as a probe

The detection and assignment of NMR spectroscopic signals of carbon atoms from carbonyl and carboxylate groups in the loop hosting the Ce(III) ion was performed for the cerium-substituted calcium-binding protein calbindin D9k. This provided a tool to characterize in solution the first coordination sphere of the metal ion. Due to the well-documented possibility of replacing calcium with metal ions of the Ln(III) series, this approach turns out to be extremely efficient for characterizing in solution the coordination of calcium ions in proteins, independently of the availability of X-ray crystal structures. The present approach completes the structural characterization of lanthanide-substituted calcium-binding proteins, for which the role of long-range constraints arising from hyperfine interaction and self-orientation has already been assessed.

Determination of recombinant human epidermal growth factor (rhEGF) in a pharmaceutical formulation by high performance liquid chromatography with electrochemical detection

A novel HPLC method with electrochemical detection has been developed for the determination of recombinant human epidermal growth factor (rhEGF) in pharmaceutical products. rhEGF was separated from other components in formulation on a reversed-phase C18 column with 24% acetonitrile in 0.1 M phosphate buffer (pH 4.75). The optimum electrochemical oxidation of EGF was obtained at 0.85 V vs. Ag/AgCl in a glassy carbon working electrode due to electroactive tyrosine, tryptophan, methionine, and arginine residues. The quantitation range was from 1.0 to 200 ng of rhEGF with the linear correlation coefficient greater than 0.999. The method was successfully applied for the quantitation of rhEGF in a pharmaceutical preparation.

Development and application of a quantitative, specific assay for Cryptosporidium parvum oocyst detection in high-turbidity environmental water samples

Chlorine-resistant Cryptosporidium parvum oocysts in drinking water play an important role in the epidemiology of cryptosporidiosis. Current methods of detecting these organisms in water are insensitive, labor-intensive, highly subjective, and severely limited by sample turbidity. We describe here an alternative technique utilizing electrochemiluminescence (ECL) technology for detecting C. parvum oocysts in environmental water samples. This method is quantitative, reproducible, and requires only minimal sample processing. Currently, the ECL assay can detect as few as one oocyst in one milliliter of concentrated test sample with sample turbidity of up to 10,000 nephelometric turbidity units. Water and sewer samples collected during a cryptosporidiosis outbreak were tested by ECL assay. Cryptosporidium parvum oocysts were found in the source water at the time of outbreak, and a sharply decreasing level of oocysts in sewer samples was observed over a three-month period following the outbreak.

Indomethacin-loaded methoxy poly(ethylene glycol)/ poly(epsilon-caprolactone) diblock copolymeric nanosphere: pharmacokinetic characteristics of indomethacin in the normal Sprague-Dawley rats

We prepared the drug-loaded polymeric nanospheres composed of the methoxy poly(ethylene glycol) (MePEG) and poly(epsilon-caprolactone) (PCL) that showed a narrow size distribution and average diameter of less than 200 nm. We could obtain the nanosphere having a relatively high drug-loading efficiency of about 42% when the feed weight ratio of indomethacin (IMC) to polymer was 1:1. To investigate the IMC pharmacokinetics in the IMC-loaded MePEG/PCL nanosphere (DMEP70) using the rats as animal model, we analyzed the IMC concentration in plasma with HPLC after i.v. bolus administered at a dose of 10 mg/kg in free IMC (control) and IMC-loaded MePEG/PCL nanosphere (DMEP70) groups via tail vein. Pharmacokinetics parameters (mean +/- s.d.) such as the mean residence time (MRT, h), the steady-state volume of distribution (Vdss, l), the terminal half-time (t 1/2, h) and the plasma clearance (CL, l/h) of IMC in each groups (control vs. DMEP70) were determined; MRT (16.97 +/- 4.83 vs. 28.69 +/- 11.28, p < 0.01); Vdss (14.26 +/- 4.86 vs. 20.37 +/- 12.04, p < 0.05); t 1/2 (15.12 +/- 4.77 vs. 23.1 +/- 8.24, p < 0.01); CL (0.84 +/- 0.27 vs. 0.71 +/- 0.41). From these results, we could concluded that MEP70 has a significant potential for sustained release and the enhancement of circulation time of loaded drug by prolonging terminal half-life, increasing MRT and Vdss of IMC. Therefore, The MePEG/PCL block copolymeric nanosphere system is being considered as promising biodegradable and biocompatible drug carrier vehicles for parentral use and may be useful as sustained release injectable delivery systems for hydrophobic drugs.

Taxol-loaded block copolymer nanospheres composed of methoxy poly(ethylene glycol) and poly(epsilon-caprolactone) as novel anticancer drug carriers

We prepared the methoxy poly(ethylene glycol) (MePEG)/poly(epsilon-caprolactone) (PCL) amphiphilic block copolymeric nanospheres containing taxol which has promising anticancer activity. MePEG/PCL block copolymeric nanospheres (MEP50) showed a narrow size distribution and an average diameter of less than 100 nm. When the initial weight ratio of taxol to polymer was 0.5:1.0, we could obtain the nanospheres having a relatively high drug-loading of more than about 20%. The size of the MePEG/PCL nanospheres also increased according to the taxol loading. However, the nanospheres did not exhibit a significant change in the size distribution and also showed a size of less than 100 nm for even that with drug-loading content (DLC) of about 20%. From the 1H NMR analysis, we identified that the MePEG/PCL nanospheres prepared by dialysis procedure have core-shell structure consisting of the hydrophilic outer shell of MePEG and the hydrophobic inner core of PCL. We confirmed the low toxicity of MePEG/PCL nanospheres (MEP70) in the acute toxicity study using male ICR mice. In addition, considering the extremely lipophilic characteristics of taxol, this MePEG/PCL, nanosphere system with high taxol loading content and suspended properties in water could be useful for the delivery of taxol.

Cloning and expression of hamster telomerase catalytic subunit cDNA

Topical application of 7,12-dimethylbenz(alpha)-anthracene induces tumors in the hamster cheek pouch. Telomerase activity is increased in the cancer tissues if compared to normal adjacent tissues in both human and hamster oral cancer. In order to achieve a probe and to investigate the putative role of telomerase in oral carcinogenesis using the hamster cheek pouch model, we have cloned the cDNA encoding the hamster telomerase catalytic subunit (hamTERT). The hamster TERT cDNA encoded 1128 amino acids and shared 64% amino acid identity with human TERT and 80% with murine TERT. As noted with human TERT which express several alternatively spliced mRNAs, we have also detected one alternatively spliced hamTERT mRNA in hamster cancer cells. Transient transfection of hamTERT cDNA in a retroviral expression vector reconstituted telomerase activity in the telomerase negative human lung fibroblast IMR90 cells.

Magnolol reduces myocardial ischemia/reperfusion injury via neutrophil inhibition in rats

The accumulation of oxygen-free radicals and activation of neutrophils are strongly implicated as important pathophysiological mechanisms mediating myocardial ischemia/reperfusion injury. It has been proven that various antioxidants have cardioprotective effects. Magnolol, an active component extracted from the Chinese medicinal herb Magnolia officinalis, possesses potent antioxidant and free radical scavenging activities. In this study, the cardioprotective activity of magnolol was evaluated in an open-chest anesthetized rat model of myocardial ischemia/reperfusion injury. The results demonstrated that pretreatment with magnolol (0.2 and 0.5 microg/kg, i.v. bolus) at 10 min before 45 min of left coronary artery occlusion, significantly suppressed the incidence of ventricular fibrillation and mortality when compared with the control group. Magnolol (0.2 and 0.5 microg/kg) also significantly reduced the total duration of ventricular tachycardia and ventricular fibrillation. After 1 h of reperfusion, pretreatment with magnolol (0.2 and 0.5 microg/kg) caused a significant reduction in infarct size. In addition, magnolol (0.2 microg/kg) significantly reduced superoxide anion production and myeloperoxidase activity, an index of neutrophil infiltration in the ischemic myocardium. In addition, pretreatment with magnolol (0.2 and 0.5 microg/kg) suppressed ventricular arrhythmias elicited by reperfusion following 5 min of ischemia. In vitro studies of magnolol (5, 20 and 50 microM) significantly suppressed N-formylmethionyl-leucyl-phenylalanine (fMLP; 25 nM)-activated human neutrophil migration in a concentration-dependent manner. It is concluded that magnolol suppresses ischemia- and reperfusion-induced ventricular arrhythmias and reduces the size of the infarct resulting from ischemia/reperfusion injury. This pronounced cardioprotective activity of magnolol may be mediated by its antioxidant activity and by its capacity for neutrophil inhibition in myocardial ischemia/reperfusion.

Szygium aromaticum (L.) Merr. Et Perry (Myrtaceae) flower bud induces apoptosis of p815 mastocytoma cell line

This study was conducted to investigate SAFB-induced apoptosis of mast cells as it pertains to both its basic drug mechanism and the potential therapeutics of the pathologic conditions accompanying mast cell proliferation. SAFB induced many apoptotic manifestations as evidenced by changes in cell morphology, generation of DNA fragmentation, activation of caspase 3, and DNA hypoploidy. The reduction of mitochondrial membrane potential and the release of cytochrome c to cytosol were also demonstrated. However, reduction of mitochondrial membrane potential and cytochrome c release were not prevented by caspase inhibitor zVAD-fmk or PTP blockers such as bongkrekic acid and cyclosporin A. Expression levels of Bcl-2 and Fas remained unchanged following SAFB treatment. This results suggest that the clinical effect of SAFB may depend on the pharmacological mechanism regulating the demise of mast cells.

Angiotensin II and its metabolites stimulate PAI-1 protein release from human adipocytes in primary culture

Plasminogen activator inhibitor (PAI)-1 is the main inhibitor of the fibrinolytic system and was recently shown to be produced by adipose cells. Obesity is associated with an increased production and release of PAI-1 protein. The aim of this study was to investigate the role of angiotensin (Ang) II and its degradation products for PAI-1 release from human adipose cells. For this purpose, we used the model of in vitro differentiated human adipocytes in primary culture. Exposure of human adipocytes to Ang II resulted in a dose- and time-dependent stimulation of PAI-1 release into the culture medium. The maximum effect of Ang II was found at a concentration of 10(-5) mol/L for 48 hours, increasing PAI-1 release by 276+/-53% compared with control cultures (P<0.05). This stimulation was preceded by an increase in specific PAI-1 mRNA copies by 65+/-12% (P<0.05), with a maximum after 6 hours. Incubation of adipocytes with 10(-5) mol/L Ang III and Ang IV, respectively, also resulted in a stimulation of PAI-1 release into the medium by 195+/-60% (P<0.05) and 142+/-24% (P<0.05), respectively, compared with control cultures. Addition of the angiotensin-receptor subtype 1 (AT(1)) blocker candesartan abolished the stimulatory action of Ang II and its metabolites, indicating that this effect is mediated by AT(1). Addition of the AT(1) blocker alone to unstimulated cultures reduced PAI-1 release by 41%+/-25% (P<0.05), suggesting that endogenous Ang II synthesis contributes to PAI-1 secretion from adipose tissue in an autocrine/paracrine manner. In conclusion, Ang II and its metabolites promote PAI-1 production and release by human fat cells and may contribute to the impairment of the fibrinolytic system typical for obesity. AT(1) receptor blockade reduces basal and abolishes Ang II-stimulated PAI-1 release from human adipocytes.