Vasorelaxant Effect of Prunus mume (Siebold) Siebold & Zucc. Branch through the Endothelium-Dependent Pathway

Korean plum (Prunus mume (Siebold) Siebold & Zucc.) has long been used as a health food or herbal medicine in Asia. Previous studies have shown that several plants of the genus Prunus have vasodilatory and antihypertensive effects; we hypothesized that P. mume branches may have a vasorelaxant effect. In this study, we evaluated the effects and action mechanism of 70% ethanol extract of P. mume branch (PMB) on isolated rat aortic rings. Inhibitors such as NG-nitro-l-arginine methyl ester, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, methylene blue, indomethacin, atropine, tetraethylammonium chloride, glibenclamide, 4-aminopyridine and BaCl₂ were used to investigate the mechanism of vasodilation responsible for the vascular relaxation. PMB (2-30 μg/mL) induced vasorelaxation in the presence of vascular endothelium, and all inhibitors used in this study affected the degree of relaxation. These results suggest that the vasorelaxant effect of PMB is endothelium-dependent and affects the nitric oxide-cyclic guanosine monophosphate pathway, prostacyclin pathway, muscarinic receptor pathway, and potassium channels. Our study explains that PMB may be another approach to hypertension treatment to reduce the burden of cardiovascular disease.

Endothelium-Dependent Vasorelaxant Effect of Prunus Persica Branch on Isolated Rat Thoracic Aorta

Peach (Prunus persica (L.) Batsch) is a popular fruit consumed by people worldwide, owing to its pleasant flavor and high mineral nutrient content. A few plants from the genus Prunus, such as Prunus yedoensis, Prunus cerasus, and Prunus serotina have shown vasorelaxant and vasodilatory effects, to date, no study has investigated the vasorelaxation effects of the P. persica branch extract (PPE). The vasorelaxant effect of PPE was endothelium-dependent, and it was related to the NO-sGC-cGMP, vascular prostacyclin, and muscarinic receptor transduction pathway. K⁺ channels, such as the BK_Ca, K_V, and K_ATP channels, were partially associated with PPE-induced vasorelaxation. PPE was effective in relaxing serotonin (5-HT)- or angiotensin II-induced contraction; furthermore, PPE attenuated Ca²⁺-induced vasoconstriction by IP₃ receptors in the SR membrane, but its vasorelaxant effect was not associated with the influx of extracellular Ca²⁺ via receptor-operative Ca²⁺ channels or voltage-dependent Ca²⁺ channels. Recognizing the rising use of functional foods for hypertension treatment, our findings imply that PPE may be a natural antihypertensive agent.

Experimental research of hypotensive and hypolipidemic effects with Modified Sanhuang Xiexin Decoction ()

OBJECTIVE

To investigate the hypotensive and hypolipidemic effects of Modified Sanhuang Xiexin Decoction (, HVC1), a herbal prescription for the vascular diseases in Chinese medicine and evaluate the acute and subchronic oral toxicities.

METHODS

Fifty-six spontaneous hypertensive rats (SHRs) were used to investigate the hypotensive and hypolipidemic effect of HVC1. Rats in the normal group (n=8) were fed with normal diet. The rats in the other groups (n=48) were fed with high fat and cholesterol diet for inducing hyperlipidemia models. Forty-eight rats were randomly divided into 6 groups [model, positive control (amlodipine, simvastain), 50, 250, and 1,000 mg/(kg•d) HVC1 groups] with 8 animals in each group. Normal and model groups were treated with distilled water [1 mL/(kg•d)], the positive control group was treated with amlodipine [5 mg/(kg•d)] or simvastatin [10 mg/(kg•d)], and the HVC1 groups were treated with HVC1 [50, 250, or 1,000 mg/(kg•d)] for 8 weeks, respectively. Blood pressure (BP) of the rats was measured using a non-invasive tail cuff system. On the last day of the experiment, serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG) levels were measured. To investigate the safety of HVC1, acute and subchronic toxicity studies were conducted on Sprague-Dawley rats. In toxicity studies, the body weight, food and water consumption of rats were measured and clinical signs observation, ophthalmologic examinations, urinalysis, hematological analysis, and serum biochemical analysis were performed.

RESULTS

A dose of 50 and 250 mg/(kg•d) HVC1 lowered systolic and diastolic BP (P<0.05). HVC1 at 1,000 mg/(kg•d) decreased TC, LDL-C and TG levels, respectively (P<0.01 or P<0.05) and 250 mg/(kg•d) HVC1 decreased TG levels on hyperlipidemic SHRs (P<0.05). In the acute toxicity study, oral administration of HVC1 did not show any toxicity effect, and the median lethal dose value of HVC1 was greater than 5,000 mg/kg. In the subchronic toxicity study, oral administration of HVC1 for 4 weeks also did not show any toxicity effect, and the no-observedadverse-effect-level of HVC1 was established as 2,000 mg/(kg•d).

CONCLUSION

These results could be used as preclinical data for clinical trials that develop HVC1 as a herbal medicine for treating or preventing hypertension and hyperlipidemia.

Vasorelaxant effects of Angelica decursiva root on isolated rat aortic rings

BACKGROUND

Hypertension is one of the most important risk factors for cardiovascular disease (CVD) and a worldwide problem. Despite increases in the development of synthetic drugs for hypertension treatment, the rate of untreated and uncontrolled hypertension remains high. These drugs are effective, but can also cause side effects. Approximately 80% of the world population uses herbal medicines because of their low toxicity and better acceptability by the human body. Therefore, we attempted to identify natural medications for treating hypertension. The 70% ethanol extract of Angelica decursiva root (ADE) shows strong vasorelaxant potential, but no studies have investigated the mechanisms underlying the vasorelaxation effect of A. decursiva.

METHODS

Dried root of A. decursiva was identified by DNA sequencing and was extracted once with 1 L 70% ethanol (EtOH) for 3 h in a reflux apparatus at 70 °C. ADE was evaluated for its vasorelaxant effects in rat thoracic aortas. Various inhibitors of ADE-induced vasorelaxation were used.

RESULTS

ADE showed vasorelaxant effects on the intact and denuded endothelium of aortic rings pre-contracted with phenylephrine and KCl in Krebs-Henseleit solution. Tetraethylammonium and 4-aminopyridine did not alter ADE-induced vasorelaxation. However, the vasorelaxant effect of ADE was partially inhibited by pre-treatment with glibenclamide an ATP-sensitive K+ channel blocker. Furthermore, ADE concentration-dependently inhibited Ca2+ supplementation-induced vasoconstriction of aortic rings that had been pretreated with phenylephrine or KCl in Ca2+-free Krebs-Henseleit solution.

CONCLUSIONS

These results suggest that ADE-induced vasorelaxation occurred in an endothelium-independent manner. The vasorelaxant effects of ADE were correlated with blockade of the KATP channel and inhibition of Ca2+ influx via receptor-operative Ca2+ channels or voltage-dependent Ca2+ channels.

Hypolipidemic effects of HVC1 in a high cholesterol diet‑induced rat model of hyperlipidemia

HVC1, a novel formation containing four herbs, was developed and its hypolipidemic effects in rats with high cholesterol diet (HCD)-induced hyperlipidemia were investigated. The rats were given a HCD for 8 weeks. The HVC1-treated groups were orally administered HVC1 at doses of 10, 50 or 250 mg/kg, respectively, and the simvastatin group was treated at a dose of 10 mg/kg. The normal diet and HCD control groups were administered with physiological saline. Oral administration of HVC1 (10, 50 or 250 mg/kg) significantly reduced the body weight of rats with hyperlipidemia and regulated the total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol levels in the serum. In addition, tissue analysis revealed that lipid accumulation in the liver and aorta was reduced by HVC1 administration. Furthermore, HVC1 significantly reduced the mRNA expression of peroxisome proliferator-activated receptor-γ, 3-hydroxy-3-methylglutaryl-CoA reductase and low-density lipoprotein receptor, as well as the protein level of 5′ adenosine monophosphate-activated protein kinase in the liver. The results clearly demonstrate that HVC1 has a potent hypolipidemic effect, and suggest that HVC1 should be evaluated as a potential treatment for hyperlipidemia.

Effect of Acer tegmentosum bark on atopic dermatitis-like skin lesions in NC/Nga mice

ETHNOPHARMACOLOGICAL RELEVANCE

Atopic dermatitis (AD) is a chronic and relapsing inflammatory condition characterized by pruritic and eczematous skin lesions that requires safe and effective pharmacological therapy. The bark of Acer tegmentosum Maxim trees has been used in Korean folk and traditional medicine to treat abscesses, surgical bleeding, liver diseases, and AD.

AIM OF STUDY

To investigate the therapeutic effect of A. tegmentosum, on a mouse model of Dermatophagoides farinae (Df)-induced AD.

METHODS

Development of AD-like skin lesions was induced by repetitive skin contact with barrier-disrupted backs of NC/Nga mice with Df body ointment, and the effects of A. tegmentosum were evaluated on the basis of histopathological skin assessment results, ear swelling, and cytokine production in the dorsal skin. The component of A. tegmentosum, salidroside, inhibited the production of TSLP in KCMH-1 cells, which indicated that its production could be pharmacologically regulated.

RESULTS

Topical application of A. tegmentosum for 1 week after Df body ointment challenge significantly reduced ear swelling and improved dorsal skin lesions. Suppression of dermatitis by combined therapy was accompanied by a decrease in the skin level of Th2 cytokines, such as interleukin (IL)-4, IL-5 and IL-13, plasma levels of thymus and activation-regulated chemokine, and IgE. Induction of thymic stromal lymphopoietin, which leads to a systemic Th2 response, was also reduced in in vivo and in vitro by A. tegmentosum and salidroside.

CONCLUSIONS

Our findings suggest that A. tegmentosum treatment has a significant therapeutic effect on Df-induced AD-like skin lesions on NC/Nga mice through inhibition of thymic stromal lymphopoietin and IgE via a mechanism that may inhibit Th2-mediated immune responses. These results suggest that A. tegmentosum and salidroside may be useful tools for the treatment of AD.

Investigation of the mechanisms of Angelica dahurica root extract-induced vasorelaxation in isolated rat aortic rings

BACKGROUND

The root of Angelica dahurica Bentham et Hooker (Umbelliferae) has been used as a traditional medicine for colds, headache, dizziness, toothache, supraorbital pain, nasal congestion, acne, ulcer, carbuncle, and rheumatism in China, Japan, and Korea. Interestingly, it has been used in the treatment of vascular diseases including hypertension. The aim of this study was to provide pharmacological evidence for the anti-hypertensive effect of A. dahurica by investigating the mechanism underlying its vasorelaxant effect.

METHODS

The vasorelaxant effects of a 70% methanol extract of the A. dahurica root (ADE) on rat thoracic aorta and its underlying mechanisms were assessed. Isolated rat aortic rings were suspended in organ chambers containing 10 ml Krebs-Henseleit (K-H) solution and placed between 2 tungsten stirrups and connected to an isometric force transducer. Changes in tension were recorded via isometric transducers connected to a data acquisition system.

RESULTS

ADE causes concentration-dependent relaxation in both endothelium-intact and endothelium-denuded aortic rings precontracted with phenylephrine (PE; 1 μM) or potassium (KCl; 60 mM) in K-H solution. And pre-treatment with ADE (1 mg/ml) inhibited calcium-induced vasocontraction of aortic rings induced by PE or KCl. However, ADE pre-treatment did not affect the contraction induced by PE or caffeine in Ca(2+)-free K-H solution.

CONCLUSIONS

These results suggested that the ADE has vasorelaxant effect and the vasorelaxant activity is mediated by endothelium-independent pathway that includes the blockade of extracellular calcium influx through the receptor-operated Ca(2+) channel and voltage-dependent calcium channel pathways.

Effect of Ampelopsis Radix on wound healing in scalded rats

Background

Ampelopsis Radix has been used as a traditional Korean medicine for the treatment of burns and scalds. However, there has been no scientific research to date on the wound healing properties of Ampelopsis Radix for scald burns. This study aimed to evaluate the healing effect of Ampelopsis japonica root tuber ethanol extract (AJE) on induced cutaneous scald injury in Sprague Dawley (SD) rats.

Methods

Hot water scalds were induced in SD rats, who were then divided into the following 5 groups; 1) control group without treatment, 2) positive control group with 1 % Silver sulfadiazine (SSD), 3) Vaseline group, and groups 4) and 5) that used Vaseline containing 5 % and 20 % AJE, respectively. The ointment was applied topically to the experimental rats, once daily for 21 days, starting at 24 h post induction of the scald injury. Gross examination, measurement of wound size, and histopathological examination were performed. And quantitative measurement of cytokine levels of tumor necrosis factor alpha (TNF-α), interleukin-10 (IL-10), transforming growth factor beta 1 (TGF-β1), and vascular endothelial growth factor (VEGF) were performed by enzyme-linked immunosorbent assay.

Results

Clinical evaluation showed that the AJE and Vaseline groups, rapidly desquamated scab on day 12 post-scalding; in particular, the 20 % AJE group achieved the greatest extent of skin recovery. Sizes of scald wound were significantly lower on days 12, 15, 18, and 21 in the AJE treated groups compared to the control groups. Histopathological evaluation showed a well-organized epithelial layer, angiogenesis, tissue granulation and collagen formation with the exception of inflammatory cells in the AJE-treated groups compared to the control groups on day 14, indicating that tissue regeneration had occurred. AJE treatment decreased TNF-α and increased IL-10 levels on days 2 and 14, indicating the anti-inflammatory action of AJE. The AJE groups also showed a decrease in TGF-β1 levels on day 7 and VEGF on day 14 in the serum of scald inflicted SD rat model.

Conclusions

These results suggest that AJE possesses scald wound healing activity via accelerating the scald wound repair during the inflammation and proliferative phases of the healing process.

Anti-inflammatory effect of Prunus yedoensis through inhibition of nuclear factor-κB in macrophages

Background

Prunus yedoensis (PY) is a traditional anti-allergy and anti-inflammatory herb medicine used in South Korea. However, until date, little is known regarding its mechanism of action.

Methods

In order to elucidate the mechanism of anti-inflammatory effect of PY, the constituents of PY were analysed by high performance liquid chromatography (HPLC), and nitric oxide (NO) and prostaglandin E₂ (PGE₂) production were measured enzyme-linked immuno sorbent assay (ELISA). The expression levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and nuclear factor-κB (NF-κB) were also measured by western blotting in lipopolysaccharide (LPS)-induced RAW 264.7 macrophage cells treated with PY.

Results

The results indicate that (50, 100 μg/mL) methanol and ethyl acetate fractionation extracts of PY not only inhibited LPS-mediated NO production and iNOS expression, but also decreased LPS-induced PGE₂ production and COX-2 expression. The anti-inflammatory effects of PY were also due to the attenuation of nuclear translocation of NF-κB, as evaluated by the use of anti-p50 on nuclear fractions. LPS-induced nuclear translocation of NF-κB decreased significantly by the methanol extract and ethyl acetate fraction of PY. High performance liquid chromatography (HPLC) analyses revealed that methanol extract and ethyl acetate fraction have similar patterns of retention time and peaks.

Conclusion

Our results demonstrate that methanol extracts and the ethyl acetate fraction of PY have anti-inflammatory properties, thus emphasizing the potential of PY as a natural health product.

The aerial part of Taraxacum coreanum extract has an anti-inflammatory effect on peritoneal macrophages in vitro and increases survival in a mouse model of septic shock

ETHNOPHARMACOLOGICAL RELEVANCE

Taraxacum coreanum Nakaiis a dandelion native to Korea and is widely consumed as an edible and medicinal herb. The aerial part of Taraxacum coreanum (TC) has been used therapeutically as a diuretic and anti-inflammatory agent, but its mechanism of action has not yet been evaluated.

AIM OF THE STUDY

To investigate the anti-inflammatory potential of a Taraxacum coreanum chloroform fraction(TCC) and its mechanisms of action in vitro and in vivo.

MATERIALS AND METHODS

Isolated mouse peritoneal macrophages were stimulated in vitro with interferon-γ (IFN-γ) and lipopolysaccharide (LPS) in the presence or absence of TCC. The anti-inflammatory effects of TCC were assessed by measuring nitric oxide (NO) and prostaglandin E2 (PGE2) production, as well as expression of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), IκBα, phospho-IKK, mitogen-activated protein kinases (MAPKs), and signal transducer and activator of transcription (STAT1). The effects of TCC were tested in vivo by measuring cytokine production and survival in a mouse model of lethal septic shock. And the standard compounds of Taraxacum coreanum were analyzed by HPLC using a C18 column.

RESULTS

Treatment of primary macrophages with TCC in vitro significantly inhibited all of the inflammatory parameters measured, including LPS-induced NO and PGE2 production, iNOS and COX-2 expression, IκBα degradation, IKK phosphorylation, and MAPK and STAT1 activation. In a mouse model of LPS-induced septic shock, TCC inhibited the production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, and increased survival by 83%.Standard compounds (gallic acid, syringic acid) of Taraxacum coreanum were qualified by HPLC analysis.

CONCLUSIONS

TCC possesses potent anti-inflammatory activity in vitro and in vivo, which occurs at least partly through inhibition of proinflammatory signaling and mediator release. These results strongly support the therapeutic potential of TCC as an anti-inflammatory agent in vivo.

Vasorelaxant effect of Prunus yedoensis bark

Background

Prunus yedoensis Matsum. is used as traditional medicine—‘Yaeng-Pi’ or ‘Hua-Pi’—in Japan and Korea. However, no studies have examined the pharmacological activities of the P. yedoensis bark. Only the antioxidant and antiviral activities of P. yedoensis fruit and the anti-hyperglycaemic effect of P. yedoensis leaf have been investigated. While studying the antihypertensive effects of several medicinal plants, we found that a methanol extract of P. yedoensis bark (MEPY) had distinct vasorelaxant effects on rat aortic rings.

Methods

The aortic rings were removed from Sprague–Dawley rats and suspended in organ chambers containing 10 ml Krebs-Henseleit solution. The aortic rings were placed between 2 tungsten stirrups and connected to an isometric force transducer. Changes in tension were recorded via isometric transducers connected to a data acquisition system.

Results

MEPY relaxed the contraction induced by phenylephrine (PE) both in endothelium-intact and endothelium-denuded aortic rings concentration dependently. However, the vasorelaxant effects of MEPY on endothelium-denuded aortic rings were lower than endothelium-intact aortic rings. The vasorelaxant effects of MEPY on endothelium-intact aortic rings were reduced by pre-treatment with l-NAME, methylene blue, or ODQ. However, pre-treatment with indomethacin, atropine, glibenclamide, tetraethylammonium, or 4-aminopyridine had no affection. In addition, MEPY inhibited the contraction induced by extracellular Ca²⁺ in endothelium-denuded rat thoracic aorta rings pre-contracted by PE (1 μM) or KCl (60 mM) in Ca²⁺-free solution.

Conclusions

Our results suggest that MEPY exerts its vasorelaxant effects via the activation of NO formation by means of l-Arg and NO-cGMP pathways and via the blockage of extracellular Ca²⁺ channels.

Inhibition of lipopolysaccharide-induced nitric oxide and prostaglandin E2 production by chloroform fraction of Cudrania tricuspidata in RAW 264.7 macrophages

BACKGROUND

Cudrania tricuspidata extract is an important traditional herbal remedy for tumors, inflammation, gastritis, and liver damage and is predominantly used in Korea, China, and Japan. However, the anti-inflammatory effects of the extract have not yet been conclusively proved.

METHODS

In this study, we investigated the effects of the CHCl3 fraction (CTC) of a methanol extract of C. tricuspidata on the lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production in RAW 264.7 macrophage cells and mouse peritoneal macrophages, and the levels of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 in RAW 264.7 macrophage cells.

RESULTS

We observed that the protein expression levels of inducible NO synthase and COX-2 enzymes were markedly inhibited by CTC in a concentration-dependent manner. In addition, CTC reduced the production of TNF-α, IL-1β, and IL-6 in the LPS-stimulated RAW 264.7 macrophage cells.

CONCLUSIONS

Our results show that the C. tricuspidata extract could modulate macrophage-mediated inflammatory functions such as the overproduction of cytokines, NO, and PGE2. The CTC was found to be the active fraction in this context.

Hypolipidemic effect of MeOH extract of Bambusae Caulis in Taeniam in hyperlipidemia induced by Triton WR-1339 and high cholesterol diet in rats

Hyperlipidemia has been implicated in atherosclerosis which is the leading cause of death among world population and resulting from lipid metabolic changes is a major cause of atherosclerosis. Bambusae Caulis in Taeniam belongs to Bambusaceae is the stem of Phyllostachys nigra (Lodd.) Munro var. henonis (Bean) Stapf of Phyllostachys bambusoides Siebold et Zuccarini, the perennial evergreen tree. The green middle layer of stem is dried in string-shape I shadow after the bark had been removed. In this study, the effects of middle layer of PN, PB, PP, and BCT on rat with hyperlipidemia, induced by Triton WR-1339 and high cholesterol diet were investigated. We measured plasma levels of triglyceride, total cholesterol, low-density lipoprotein (LDL)-cholesterol, and high-density lipoprotein (HDL)-cholesterol as measure of its hyperlipidemic effects. As a result, all of the Bambusae Caulis in Taeniam was reduced total cholesterol, LDL. Inhibition rate on LDL-oxidation, hACAT-1, and hACAT-2 was increased dose-dependently. Therefore all of the Bambusae Caulis in Taeniam is a good candidate for the treatment on Triton WR-1339 and high cholesterol diet-induced blood circulatory disorders, obesity, and hyperlipidemia.

Lipid lowering activity of Citri unshii pericarpium in hyperlipemic rats

The inhibitory effect of the MeOH extract of Citri unshii pericarpium (CU) and its fractions were tested in hyperlipemic rats using for animal models induced by high cholesterol-diet. We measured plasma levels of triglyceride, total cholesterol, low-density lipoprotein (LDL)-cholesterol and high-density lipoprotein (HDL)-cholesterol as measures of its hyperlipemic effects. We demonstrated that CU decreases plasma levels of triglyceride, total cholesterol and LDL cholesterol. There was also no elevation of plasma ALT and AST levels, which indicate CU did not cause liver injury. These results indicate that CU is a good candidate for the treatment on high cholesterol diet-induced blood circulatory disorders, obesity and hyperlipidemia.

Antioxidant activities of new flavonoids from Cudrania tricuspidata root bark

Two new flavonoids, hydroxybenzyl flavonoid glycosides (6-p-hydroxybenzyl kaempferol-7-O-beta-D-glucopyranoside named cudranian 1 and 6-p-hydroxybenzyl quercetin-7-O-beta-D-glucopyranoside named cudranian 2), and 3 known flavonoids (kaempferol-7-O-beta-D-glucopyranoside, quercetin-7-O-beta-D-glucopyranoside and aromadendrin) were isolated from root bark of Cudrania tricuspidata and their structures were elucidated by spectroscopic methods. These compounds showed remarkable radical scavenging effects against 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and anti-lipid peroxidation efficacy on human low-density lipoprotein by TBARS assay.

The effects of apigenin-7-O-beta-D-glucuronopyranoside on reflux oesophagitis and gastritis in rats

1. This study evaluated the inhibitory action of apigenin-7-O-beta-D-glucuronopyranoside (AGC), apigenin, and omeprazole on reflux oesophagitis and gastritis in rats. AGC was isolated from Clerodendron trichotomum leaves. 2. Oesophagitis and gastritis were induced by surgical procedure and the administration of indomethacin, respectively. The intraduodenal (i.d.) administration of AGC decreased the volume of gastric juice and increased the gastric pH compared with apigenin and omeprazole. The acid output was more inhibited by AGC in a dose-dependent manner than by apigenin and omeprazole. Compared with apigenin and omeprazole, AGC significantly decreased the size of gastric lesions, which were induced by exposure of the gastric mucosa to indomethacin. 3. Malondialdehyde (MDA) content, which is the end product of lipid peroxidation, was increased significantly after the induction of reflux oesophagitis. The MDA content was decreased by AGC (i.d. 3 mg kg(-1)), but not by either apigenin or omeprazole. This suggests that AGC has an antioxidative effect. In the oesophagitis group, the mucosal levels of glutathione (GSH) were significantly lower than that in the normal group. However, the GSH levels were preserved after administering the AGC, suggesting that AGC possesses scavenging activity. 4. In summary, AGC is more potent than apigenin and omeprazole at inhibiting reflux oesophagitis and gastritis and may therefore be a promising drug for their treatment.

The effect of luteolin-7-O-β-d-glucuronopyranoside on gastritis and esophagitis in rats

This study evaluated the inhibitory action of luteolin-7-O-beta-D-glucuronopyranoside, luteolin which was isolated from Salix gilgiana leaves, and omeprazole on reflux esophagitis and gastritis in rats. Reflux esophagitis and gastritis were induced surgically and by the administration of indomethacin, respectively. The intraduodenal administration of luteolin-7-O-beta-D-glucuronopyranoside decreased the ulcer index, injury area, gastric volume and acid output, and increased the gastric pH compared with luteolin. Luteolin-7-O-beta-D-glucuronopyranoside significantly decreased the size of the gastric lesions that had been induced by exposing the gastric mucosa to indomethacin. The malondialdehyde content, which is the end product of lipid peroxidation, was increased significantly after inducing of reflux esophagitis. The malondialdehyde content was decreased by Luteolin-7-O-beta-D-glucuronopyranoside but not luteolin or omeprazole. Luteolin-7-O-beta-D-glucuronopyranoside has a more potent antioxidative effect than luteolin. Luteolin-7-O-beta-D-glucuronopyranoside is a promising drug for the treatment of reflux esophagitis and gastritis.

Optimal Group Scheduling and Machining-Speed Decision Under Due-Date Constraints

A group scheduling model which is associated with group technology concepts was developed on the multiple production stages. In group scheduling where jobs are classified into several groups, optimal decision is to be made as to sequences of groups and jobs in each group. Both optimal group and optimal job sequences were determined so as to minimize the total flow time with the minimum number of tardy jobs. In addition, optimal speeds minimizing the production cost were determined under the optimal sequences.

Machine Loading and Product-Mix Analysis for Group Technology

An analysis for machine loading was performed to optimally select parts to be manufactured in a limited amount of time available by a given production facility by applying the Group Technology concept. In addition, optimal machining speeds were determined for all products selected, so as to maximize the production rate. A computational algorithm was developed for this optimal machine loading and product-mix decision, and a sample example was demonstrated.

Group Scheduling Technique for Multiproduct, Multistage Manufacturing Systems

“Group Scheduling,” which is operations scheduling based on the Group Technology concept, was analyzed in a multistage manufacturing system. In the case of fabricating multiple parts (jobs) grouped into several group cells, both optimal group and optimal job sequences were determined such that the total flow time (makespan) was minimized, by means of the branch-and-bound method. In addition, optimal machining speeds to be utilized on multiple stages (machines) for each job were determined to reduce the total production cost as much as possible. Optimizing algorithms for this Group Scheduling Technique were also presented with numerical examples.

Wear Characteristics of Ceramic Tools

Comparative cutting performance tests of two ceramic tools in machining cast iron, AISI-4340, H-11 steel were made, and the wear patterns, wear rates, and tool life data are analyzed to evaluate the performance characteristics of ceramic tools in comparison with that of carbide tools. Also the wear process and mechanism of ceramic tools are investigated by scanning electron microscope techniques and electron microprobe analyses. Some specific causes and mechanism of tool wear are evaluated in relation to the cutting performance data.

Analysis of Tool Wear—Part I: Theoretical Models of Flank Wear

Cutting tools of sufficient strength against failure by brittle fracture or loss of “form stability” through rise of interface temperatures, still continue to fail by a process of “wear,” which is loss of cutting tool material through gradual interaction between the work and the tool material. Such wear can take place either at the principal flank surface or at the top face of the cutting tool for roughing and semiroughing cuts. Wear may also occur at the auxiliary flank surface resulting in grooving wear during fine machining or machining of high strength materials. The causes for such wear processes include (i) mechanical interaction (abrasion or adhesion and transfer type), (ii) thermochemical interaction (diffusion or chemical reaction). As a part of this investigation on tool wear, two theoretical models have been proposed for explaining mechanical wear at the flank surface. These models explain the nature and characteristics of wear growth and the sensitiveness and dependence of interaction phenomena between the tool-work pair.