Excretion of triacylglycerol as a matrix lipid facilitating apoplastic accumulation of a lipophilic metabolite shikonin

Plants produce a large variety of lipophilic metabolites, many of which are secreted by cells and accumulated in apoplasts. These compounds often play a role to protect plants from environmental stresses. However, little is known about how these lipophilic compounds are secreted into apoplastic spaces. In this study, we used shikonin-producing cultured cells of Lithospermum erythrorhizon as an experimental model system to analyze the secretion of lipophilic metabolites, taking advantage of its high production rate and the clear inducibility in culture. Shikonin derivatives are lipophilic red naphthoquinone compounds that accumulate exclusively in apoplastic spaces of these cells and also in the root epidermis of intact plants. Microscopic analysis showed that shikonin is accumulated in the form of numerous particles on the cell wall. Lipidomic analysis showed that L. erythrorhizon cultured cells secrete an appreciable portion of triacylglycerol (24-38% of total triacylglycerol), composed predominantly of saturated fatty acids. Moreover, in vitro reconstitution assay showed that triacylglycerol encapsulates shikonin derivatives with phospholipids to form lipid droplet-like structures. These findings suggest a novel role for triacylglycerol as a matrix lipid, a molecular component involved in the secretion of specialized lipophilic metabolites.

Improved Chemical Fixation of Lipid-Secreting Plant Cells for Transmission Electron Microscopy

Cultured Lithospermum erythrorhizon cells were fixed with a new fixation method to visualize the metabolism of shikonin derivatives, the lipophilic naphthoquinone pigments in Boraginaceae. The new fixation method combined glutaraldehyde containing malachite green, imidazole–osmium and p-phenylenediamine treatments, and cells were then observed with a transmission electron microscope. The method prevented the extraction of lipids, including shikonin derivatives, and improved the visualization of subcellular structures, especially the membrane system, when compared with that of conventional fixation. The improved quality of the transmission electron micrographs is because malachite green ionically binds to the plasma membrane, organelles and lipids and acts as a mordant for electron staining with osmium tetroxide. Imidazole promotes the reaction of osmium tetroxide, leading to enhanced electron staining. p-Phenylenediamine reduces osmium tetroxide bound to cellular materials and increases the electron density. This protocol requires only three additional reagents over conventional chemical fixation using glutaraldehyde and osmium tetroxide.

Modes of secretion of plant lipophilic metabolites via ABCG transporter-dependent transport and vesicle-mediated trafficking

Many lipophilic metabolites produced by terrestrial plants are deposited on plant surfaces to protect them from abiotic and biotic stresses. Plant-derived lipophilic metabolites include apoplastic biopolymers, such as wax, cutin, sporopollenin, suberin, and lignin, as well as low-molecular-weight secondary metabolites. These secreted molecules confer adaptive toughness and robustness on plants. The mechanisms responsible for the secretion of these lipophilic metabolites remain unclear, although two pathways, mediated by transporters and vesicles, have been proposed. Recent genetic and biochemical studies have shown that G-type ATP-binding cassette (ABCG) transporters and membrane trafficking factors are involved in the apoplastic accumulation of lipophilic metabolites in plants. These two distinctive modes of secretion may be either exclusive or collaborative. This review describes these transporter-dependent and vesicle-mediated mechanisms underlying the secretion of lipophilic metabolites.

Arabidopsis ECHIDNA protein is involved in seed coloration, protein trafficking to vacuoles, and vacuolar biogenesis

Flavonoids are a major group of plant-specific metabolites that determine flower and seed coloration. In plant cells, flavonoids are synthesized at the cytosolic surface of the endoplasmic reticulum and are sequestered in the vacuole. It is possible that membrane trafficking, including vesicle trafficking and organelle dynamics, contributes to flavonoid transport and accumulation. However, the underlying mechanism has yet to be fully elucidated. Here we show that the Arabidopsis ECHIDNA protein plays a role in flavonoid accumulation in the vacuole and protein trafficking to the vacuole. We found defective pigmentation patterns in echidna seed, possibly caused by reduced levels of proanthocyanidins, which determine seed coloration. The echidna mutant has defects in protein sorting to the protein storage vacuole as well as vacuole morphology. These findings indicate that ECHIDNA is involved in the vacuolar trafficking pathway as well as the previously described secretory pathway. In addition, we found a genetic interaction between echidna and green fluorescent seed 9 (gfs9), a membrane trafficking factor involved in flavonoid accumulation. Our findings suggest that vacuolar trafficking and/or vacuolar development, both of which are collectively regulated by ECHIDNA and GFS9, are required for flavonoid accumulation, resulting in seed coat pigmentation.

A Cytosol-Localized Geranyl Diphosphate Synthase from Lithospermum erythrorhizon and Its Molecular Evolution

Geranyl diphosphate (GPP) is the direct precursor of all monoterpenoids and is the prenyl source of many meroterpenoids, such as geranylated coumarins. GPP synthase (GPPS) localized in plastids is responsible for providing the substrate for monoterpene synthases and prenyltransferases for synthesis of aromatic substances that are also present in plastids, but GPPS activity in Lithospermum erythrorhizon localizes to the cytosol, in which GPP is utilized for the biosynthesis of naphthoquinone pigments, which are shikonin derivatives. This study describes the identification of the cytosol-localized GPPS gene, LeGPPS, through EST- and homology-based approaches followed by functional analyses. The deduced amino acid sequence of the unique LeGPPS showed greater similarity to that of farnesyl diphosphate synthase (FPPS), which generally localizes to the cytosol, than to plastid-localized conventional GPPS. Biochemical characterization revealed that recombinant LeGPPS predominantly produces GPP along with a trace amount of FPP. LeGPPS expression was mainly detected in root bark, in which shikonin derivatives are produced, and in shikonin-producing cultured cells. The GFP fusion protein in onion (Allium cepa) cells localized to the cytosol. Site-directed mutagenesis of LeGPPS and another FPPS homolog identified in this study, LeFPPS1, showed that the His residue at position 100 of LeGPPS, adjacent to the first Asp-rich motif, contributes to substrate preference and product specificity, leading to GPP formation. These results suggest that LeGPPS, which is involved in shikonin biosynthesis, is recruited from cytosolic FPPS and that point mutation(s) result in the acquisition of GPPS activity.

Highly efficient method of Lithospermum erythrorhizon transformation using domestic Rhizobium rhizogenes strain A13

Lithospermum erythrorhizon, a medicinal plant growing in Asian countries, produces shikonin derivatives that are lipophilic secondary metabolites. These red naphthoquinone pigments are traditionally used as a natural drug and a dye in East Asia. In intact L. erythrorhizon plants, shikonin derivatives are produced in the root epidermal cells and secreted into extracellular spaces. The biosynthetic pathway for shikonin derivatives remains incompletely understood and the secretion mechanisms are largely unknown. Understanding the molecular mechanisms underlying shikonin biosynthesis and transport in L. erythrorhizon cells requires functional analysis of candidate genes using transgenic plants. To date, however, standard transformation methods have not yet been established. This study describes an efficient method for L. erythrorhizon transformation using hairy roots by Rhizobium rhizogenes strain A13, present domestically in Japan. Hairy roots of L. erythrorhizon were generated from explants of the axenic shoots that were infected with R. rhizogenes strain A13. Integration into the genome was assessed by PCR amplifying a transgene encoding green fluorescent protein (GFP) and by monitoring GFP expression. This method enhanced transformation efficiency 50-70%. Although methods for the systematic stable transformation of L. erythrorhizon plants have not yet been reported, the method described in this study resulted in highly efficient stable transformation using hairy roots. This method enables the functional analysis of L. erythrorhizon genes.

Convergent evolution of the UbiA prenyltransferase family underlies the independent acquisition of furanocoumarins in plants

Furanocoumarins (FCs) are plant-specialized metabolites with potent allelochemical properties. The distribution of FCs is scattered with a chemotaxonomical tendency towards four distant families with highly similar FC pathways. The mechanism by which this pathway emerged and spread in plants has not been elucidated. Furanocoumarin biosynthesis was investigated in Ficus carica (fig, Moraceae), focusing on the first committed reaction catalysed by an umbelliferone dimethylallyltransferase (UDT). Comparative RNA-seq analysis among latexes of different fig organs led to the identification of a UDT. The phylogenetic relationship of this UDT to previously reported Apiaceae UDTs was evaluated. The expression pattern of F. carica prenyltransferase 1 (FcPT1) was related to the FC contents in different latexes. Enzymatic characterization demonstrated that one of the main functions of FcPT1 is UDT activity. Phylogenetic analysis suggested that FcPT1 and Apiaceae UDTs are derived from distinct ancestors, although they both belong to the UbiA superfamily. These findings are supported by significant differences in the related gene structures. This report describes the identification of FcPT1 involved in FC biosynthesis in fig and provides new insights into multiple origins of the FC pathway and, more broadly, into the adaptation of plants to their environments.

Functional Disruption of the Tomato Putative Ortholog of HAWAIIAN SKIRT Results in Facultative Parthenocarpy, Reduced Fertility and Leaf Morphological Defects

A number of plant microRNAs have been demonstrated to regulate developmental processes by integrating internal and environmental cues. Recently, the Arabidopsis thaliana F-box protein HAWAIIAN SKIRT (HWS) gene has been described for its role in miRNA biogenesis. We have isolated in a forward genetic screen a tomato (Solanum lycopersicum) line mutated in the putative ortholog of HWS. We show that the tomato hws-1 mutant exhibits reduction in leaflet serration, leaflet fusion, some degree of floral organ fusion, and alteration in miRNA levels, similarly to the original A. thaliana hws-1 mutant. We also describe novel phenotypes for hws such as facultative parthenocarpy, reduction in fertility and flowering delay. In slhws-1, the parthenocarpy trait is influenced by temperature, with higher parthenocarpy rate in warmer environmental conditions. Conversely, slhws-1 is able to produce seeds when grown in cooler environment. We show that the reduction in seed production in the mutant is mainly due to a defective male function and that the levels of several miRNAs are increased, in accordance with previous HWS studies, accounting for the abnormal leaf and floral phenotypes as well as the altered flowering and fruit development processes. This is the first study of HWS in fleshy fruit plant, providing new insights in the function of this gene in fruit development.

SlLAX1 is Required for Normal Leaf Development Mediated by Balanced Adaxial and Abaxial Pavement Cell Growth in Tomato

Leaves are the major plant organs with a primary function for photosynthesis. Auxin controls various aspects of plant growth and development, including leaf initiation, expansion and differentiation. Unique and intriguing auxin features include its polar transport, which is mainly controlled by the AUX1/LAX and PIN gene families as influx and efflux carriers, respectively. The role of AUX1/LAX genes in root development is well documented, but the role of these genes in leaf morphogenesis remains unclear. Moreover, most studies have been conducted in the plant model Arabidopsis thaliana, while studies in tomato are still scarce. In this study, we isolated six lines of the allelic curly leaf phenotype 'curl' mutants from a γ-ray and EMS (ethyl methanesulfonate) mutagenized population. Using a map-based cloning strategy combined with exome sequencing, we observed that a mutation occurred in the SlLAX1 gene (Solyc09g014380), which is homologous to an Arabidopsis auxin influx carrier gene, AUX1 (AtAUX1). Characterization of six alleles of single curl mutants revealed the pivotal role of SlLAX1 in controlling tomato leaf flatness by balancing adaxial and abaxial pavement cell growth, which has not been reported in tomato. Using TILLING (Targeting Induced Local Lesions IN Genome) technology, we isolated an additional mutant allele of the SlLAX1 gene and this mutant showed a curled leaf phenotype similar to other curl mutants, suggesting that Solyc09g014380 is responsible for the curl phenotype. These results showed that SlLAX1 is required for normal leaf development mediated by balanced adaxial and abaxial pavement cell growth in tomato.

Plant Vacuoles

Plant vacuoles are multifunctional organelles. On the one hand, most vegetative tissues develop lytic vacuoles that have a role in degradation. On the other hand, seed cells have two types of storage vacuoles: protein storage vacuoles (PSVs) in endosperm and embryonic cells and metabolite storage vacuoles in seed coats. Vacuolar proteins and metabolites are synthesized on the endoplasmic reticulum and then transported to the vacuoles via Golgi-dependent and Golgi-independent pathways. Proprotein precursors delivered to the vacuoles are converted into their respective mature forms by vacuolar processing enzyme, which also regulates various kinds of programmed cell death in plants. We summarize two types of vacuolar membrane dynamics that occur during defense responses: vacuolar membrane collapse to attack viral pathogens and fusion of vacuolar and plasma membranes to attack bacterial pathogens. We also describe the chemical defense against herbivores brought about by the presence of PSVs in the idioblast myrosin cell.

GFS9/TT9 contributes to intracellular membrane trafficking and flavonoid accumulation in Arabidopsis thaliana

Flavonoids are the most important pigments for the coloration of flowers and seeds. In plant cells, flavonoids are synthesized by a multi-enzyme complex located on the cytosolic surface of the endoplasmic reticulum, and they accumulate in vacuoles. Two non-exclusive pathways have been proposed to mediate flavonoid transport to vacuoles: the membrane transporter-mediated pathway and the vesicle trafficking-mediated pathway. No molecules involved in the vesicle trafficking-mediated pathway have been identified, however. Here, we show that a membrane trafficking factor, GFS9, has a role in flavonoid accumulation in the vacuole. We screened a library of Arabidopsis thaliana mutants with defects in vesicle trafficking, and isolated the gfs9 mutant with abnormal pale tan-colored seeds caused by low flavonoid accumulation levels. gfs9 is allelic to the unidentified transparent testa mutant tt9. The responsible gene for these phenotypes encodes a previously uncharacterized protein containing a region that is conserved among eukaryotes. GFS9 is a peripheral membrane protein localized at the Golgi apparatus. GFS9 deficiency causes several membrane trafficking defects, including the mis-sorting of vacuolar proteins, vacuole fragmentation, the aggregation of enlarged vesicles, and the proliferation of autophagosome-like structures. These results suggest that GFS9 is required for vacuolar development through membrane fusion at vacuoles. Our findings introduce a concept that plants use GFS9-mediated membrane trafficking machinery for delivery of not only proteins but also phytochemicals, such as flavonoids, to vacuoles.

Divalent cations enhance fluoride binding to Streptococcus mutans and Streptococcus sanguinis cells and subsequently inhibit bacterial acid production

One preventive effect of topical fluoride application is derived from the fact that fluoride can inhibit bacterial acid production. Furthermore, divalent cations such as Ca(2+) and Mg(2+) increase the binding of fluoride to bacterial cells. These findings suggest that exposure of oral bacteria to fluoride in the presence of divalent cations increases fluoride binding to bacterial cells and subsequently enhances fluoride-induced inhibition of bacterial acid production. This study investigated the effects of fluoride exposure (0-20,000 ppm F) in the presence of Ca(2+) or Mg(2+) prior to glucose challenge on pH fall ability by bacterial sugar fermentation, as well as fluoride binding to bacterial cells by exposure to fluoride, and fluoride release from bacterial cells during bacterial sugar fermentation, using caries-related bacteria, Streptococcus mutans and Streptococcus sanguinis. The pH fall by both streptococci was inhibited by exposure to over 250 ppm F in the presence of Ca(2+) (p < 0.01), whereas in the presence of Mg(2+), the pH fall by S. mutans and S. sanguinis was inhibited after exposure to over 250 and 950 ppm F, respectively (p < 0.05). The amounts of fluoride binding to and released from streptococcal cells increased with the concentration of fluoride the cells were exposed to in the presence of Mg(2+), but were high enough even after 250 ppm F exposure in the presence of Ca(2+). The enhanced inhibition of acid production in the presence of divalent cations is probably due to the improved efficiency of fluoride binding to bacterial cells being improved via these divalent cations.

Beneficial effect of JTV-803, a new synthetic inhibitor of activated factor X, against both lipopolysaccharide-induced and tissue factor-induced disseminated intravascular coagulation in rat models

We examined whether JTV-803, a specific activated factor X inhibitor independent of antithrombin III (ATIII), is effective against disseminated intravascular coagulation (DIC) in rat models induced by tissue factor (TF) or lipopolysaccharides (LPS). In male Wistar rats, DIC was induced by a 4 h infusion of thromboplastin (3.75 U/kg) or LPS (50 mg/kg). The rats were given JTV-803 (0.3 or 3 mg/kg, bolus intravenously) (JTV-803 groups) or low molecular weight heparin (LMWH groups) (200 U/kg, bolus intravenously) prior to an injection of TF or LPS. The results showed that JTV-803 was dose-dependently effective against DIC in both TF-induced and LPS-induced rat models. This anti-DIC effect of JTV-803 at higher doses was almost equivalent to that of LMWH in both types of DIC. Plasma ATIII activity was more prominent in the group treated with JTV-803 than in that treated with LMWH. None of rats died in the TF-induced DIC model with or without drug administration. On the contrary, seven of 22 rats died (mortality rate, 31.8%) in the LPS-induced DIC model without drug administration. Although the mortality rate of rats induced with LPS and treated with LMWH was quite high (6/16, 37.5%), none of the LPS-induced rats treated with JTV-803 died. These findings suggested that JTV-803 can treat both TF-induced and LPS-induced DIC models, and that this drug has greater potential in preserving ATIII and in improving the prognosis of DIC.

Purification and characterization of Delta(1)-pyrroline-5-carboxylate reductase isoenzymes, indicating differential distribution in spinach (Spinacia oleracea L.) leaves

Delta(1)-Pyrroline-5-carboxylate reductase (P5CR) (EC 1.5.1.2. L-proline: NAD(P)-5-oxidoreductase), the second enzyme in the proline biosynthetic pathway, was purified from spinach (Spinacia oleracea L.) leaves. Following ammonium sulfate fractionation, purification was performed by several chromatographic methods: Blue Cellulofine, DEAE-TOYOPEARL, Sephacryl S-300 HR, and POROS QE/M. Two isoenzymes resolved by anion exchange chromatography were designated P5CR-1 and P5CR-2. Only P5CR-2 was purified from the intact chloroplasts, indicating differential distribution of the isoenzymes. P5CR isoenzymes, P5CR-1 and P5CR-2, are a homopolymer with an apparent molecular mass of 310 kDa, consisting of 10 to 12 subunits of about 28.5 kDa. P5CR-1 and P5CR-2 showed K(m) values of 9 and 19 microM for NADPH and values of 0.122 and 0.162 mM for Delta(1)-pyrroline-5-carboxylate (P5C), respectively. We decided partial amino acid sequences of P5CR-1 which showed the 70 to 80% homology to the deduced amino acid sequences of several plant P5CR cDNAs. Both isoenzymes had much lower affinity for NADH than for NADPH and were inhibited by free ATP and Mg(2+) ion. The inhibition was partially mitigated when ATP and Mg(2+) were added simultaneously to the reaction mixture. Cations at high concentration were inhibitory to P5CR activity. Interestingly, P5CR-2 was more stable to heat treatment at 40 degrees C than P5CR-1.

All-trans retinoic acid is partially effective against lipopolysaccharide-induced but not against tissue-factor-induced disseminated intravascular coagulation in rat models

All-trans retinoic acid (ATRA) has been introduced to the management of acute promyelocytic leukemia (APL) as a differentiation treatment. This drug not only causes complete remission, but also improves disseminated intravascular coagulation (DIC) without adding anticoagulants in APL. We have attempted to determine whether ATRA is effective against DIC in rat models induced by tissue factor (TF) or lipopolysaccharide (LPS), because the anticoagulant effect of ATRA has been considered to induce thrombomodulin upregulation and TF downregulation on endothelial cells as well as on APL cells. In male Wistar rats, DIC was induced by a 4-h infusion of thromboplastin (3.75 U/kg) or lipopolysaccharide (30 mg/kg). The rats were given ATRA orally each day at a dose of 100 mg/kg per day for 1 week before the injection of TF or LPS in ATRA treatment groups, or given low molecular weight heparin (LMWH) 10 min before the injection of TF or LPS (200 U/kg, bolus intravenously) in LMWH treatment groups. No significant changes in hemostatic parameters or markers of organ dysfunction were caused by the ATRA administration, while DIC was significantly improved by LMWH in the TF-induced model. DIC was significantly improved by both ATRA and LMWH in the LPS-induced model. These findings suggested that ATRA was useful for treating DIC only in the LPS-induced model, and that drug efficacy should be carefully assessed because the agents used to induce DIC considerably influenced the outcome.

Oscillation and regulation of proline content by P5CS and ProDH gene expressions in the light/dark cycles in Arabidopsis thaliana L

The fluctuation of proline content, and protein and mRNA levels of delta1-pyrroline-5-carboxylate synthetase (P5CS) and proline dehydrogenase (ProDH), both of which are involved in proline biosynthesis and degradation, in the shoots of Arabidopsis grown in light/dark cycles were demonstrated under salt-stressed and unstressed conditions. Proline content, as well as proteins and mRNAs of these enzymes, clearly oscillated in the light/dark cycles under the stressed and unstressed conditions. A reciprocal relationship between P5CS and ProDH was observed. Protein levels of P5CS and ProDH were well synchronized with their mRNA levels, although the fluctuation of protein levels was not as significant as that of their mRNA levels. Both mRNA and protein levels of the two enzymes as well as the proline content did not oscillate under the continuous light or the dark conditions. Thus, P5CS and ProDH gene expressions seemed to be involved in light irradiation. Moreover, relative water content (RWC) in the plants oscillated in the light/dark cycles. The fluctuations of proline content in shoot reversely responded to that of RWC. It is suggested that the expression of two genes responds sensitively to a subtle change of cellular water status, and accumulated proline keeps the osmotic balance between cells and the outer environment.

Transcatheter arterial embolization for impending rupture of an isolated internal iliac artery aneurysm complicated with disseminated intravascular coagulation

A 90-year-old male, with impending rupture of an isolated internal iliac artery aneurysm (IIAA) complicated with disseminated intravascular coagulation (DIC) was successfully treated with transcatheter arterial embolization (TAE). After TAE, enlargement of the aneurysm was arrested and coagulation-fibrinolytic abnormalities induced by DIC improved without severe complications. Although IIAA is relatively rare, the post-operative mortality of patients with ruptures is reportedly high. We assessed the usefulness of this procedure for impending rupture of IIAA, especially for patients in high risk groups.

Treatment of disseminated intravascular coagulation (DIC) with all-trans retinoic acid in an endotoxin-induced rat model

Anticoagulant drugs such as heparin are often administered to patients with disseminated intravascular coagulation (DIC) who are also being treated for their underlying disease. The pathophysiology of DIC is so varied that treatment with medications other than anticoagulants may be useful. All-trans retinoic acid (ATRA), which is used for the treatment of acute promyelocytic leukemia (APL), improves DIC in APL. In vitro studies have reported that ATRA caused downregulation of tissue factor and upregulation of thrombomodulin (TM) on endothelial cells as well as APL cells. We examined the effect of ATRA in an endotoxin-induced rat DIC model. DIC was induced in male Wistar rats with a 4-h sustained infusion of endotoxin at a dose of 30 mg/kg. ATRA (20 mg/day) was given every day for 1 week before the injection of endotoxin. ATRA improved the increase in thrombin-antithrombin III (TAT) complex and D-dimer in this model. Fibrin deposition in renal glomeruli was inhibited by ATRA administration, with an increase in the intensity of immunohistochemical TM staining. These findings suggest that ATRA has beneficial effects in the endotoxin-induced rat DIC model. The mechanism may be an upregulation of TM expression on endothelial cells.

Beta3-adrenoceptors mediate relaxation of guinea pig taenia caecum by BRL37344A and BRL35135A

Beta-adrenoceptor-mediated relaxation of guinea pig taenia caecum was investigated by studying the effects of the beta3-adrenoceptor agonists, BRL37344A [(R*,R*)-(+/-)-4-[2'-[2-hydroxy-2-(3-chlorophenyl) ethylamino] propyl] phenoxyacetic acid sodium salt sesquihydrate] and BRL35135A [(R*,R*)-(+/-)-methyl-4-[2-[2-hydroxy-2-(3-chlorophenyl) ethylamine] propyl] phenoxyacetate hydrobromide]. BRL37344A and BRL35135A caused dose-dependent relaxation of the guinea pig taenia caecum. The concentration-response curves for BRL37344A and BRL35135A were unaffected by propranolol, ICI118551 [erythro-1-(7-methylindan-4-yloxy)-3-(isopropylamine)-but an-2-ol], atenolol, butoxamine, prazosin, yohimbine and phentolamine. Bupranolol produced shifts of the concentration-response curves for BRL37344A and BRL35135A. Schild regression analyses carried out for bupranolol against BRL37344A and BRL35135A gave pA2 values of 5.79 and 5.84, respectively. These results suggest that the relaxant response to BRL37344A and BRL35135A of the guinea pig taenia caecum is mediated by beta3-adrenoceptors.

The beta2- and beta3-adrenoceptor-mediated relaxation induced by isoprenaline and salbutamol in guinea pig taenia caecum

To understand the receptor subtypes responsible for beta-adrenoceptor-mediated relaxation of guinea pig taenia caecum, we investigated the effects of isoprenaline and salbutamol. Isoprenaline and salbutamol caused dose-dependent relaxation of the guinea pig taenia caecum. Propranolol, bupranolol and butoxamine produced shifts of the concentration response curves for isoprenaline and salbutamol. Schild regression analyses carried out for propranolol against isoprenaline and salbutamol gave pA2 values of 8.43 and 8.88, respectively. Schild regression analyses carried out for butoxamine against isoprenaline and salbutamol gave pA2 values of 6.46 and 6.68, respectively. Schild regression analyses carried out for bupranolol against isoprenaline and salbutamol gave pA2 values of 8.60 and 8.69, respectively. However, in the presence of 3 x 10(-4) M atenolol, 10(-4) M butoxamine and 10(-6) M phentolamine to block the beta1-, beta2- and alpha-adrenoceptor effects, respectively, Schild regression analyses carried out for bupranolol against isoprenaline and salbutamol gave pA2 values of 5.77 and 5.97, respectively. These results suggest that the relaxant responses to isoprenaline and salbutamol in the guinea pig taenia caecum are mediated by both the beta2- and the beta3-adrenoceptors.

Chemotherapy targeting regional lymph nodes by gastric submucosal injection of liposomal adriamycin in patients with gastric carcinoma

We investigated the delivery of adriamycin (ADR) to the regional lymph nodes of the stomach following the gastric submucosal injection of liposomal adriamycin (Lipo-ADR) in 34 gastric carcinoma patients, as well as following intravenous administration of free ADR (F-ADR) in another 18 patients. Prior to radical gastrectomy, Lipo-ADR was endoscopically injected into the gastric submucosa adjacent to the primary tumor via a needle-tipped catheter. After Lipo-ADR injection, the ADR concentration in the primary and secondary drainage lymph nodes was higher than in the other regional lymph nodes. Thus, the regional nodes more susceptible to metastasis showed higher levels of ADR. In contrast, the intravenous administration of F-ADR produced a similar and far lower ADR concentration in all the nodes. Delivery of ADR to the primary drainage lymph nodes following injection of 5 ml of Lipo-ADR was compared with delivery to the left gastric artery lymph nodes after intravenous administration of an equal dose of F-ADR. The ADR levels (micrograms/g) after gastric submucosal injection were 15.1 +/- 8.30 on day 1 (n = 4); and 11.9 +/- 4.80 on day 4 (n = 6). Those after intravenous administration were 0.29 +/- 0.10 on day 1 (n = 4); and 0.36 +/- 0.0 on day 4 (n = 2). The differences between the two groups were significant (P < 0.05). The ADR levels after the gastric submucosal injection were far higher than those after intravenous administration. These findings indicate that the gastric submucosal injection of Lipo-ADR can specifically deliver ADR to the regional lymph nodes at high concentrations. Such preoperative adjuvant chemotherapy targeting the regional lymph nodes may be useful for preventing the lymph node recurrence of gastric carcinoma.

Delivery of lymph node-targeted adriamycin by gastric submucosal liposomal injection in rabbits

We investigated the feasibility of specifically delivering adriamycin (ADR) to the regional lymph nodes via gastric submucosal injection of liposomal adriamycin (Lipo-ADR) in a rabbit model. We determined the tissue distribution of ADR for up to 7 days after the gastric submucosal injection of Lipo-ADR (0.4 mg/kg of ADR potency) and i.v. administration of an equal dose of free adriamycin (F-ADR). The area under the ADR concentration-time curve (AUC) of the regional lymph nodes was 85.4 micrograms.day/g after gastric submucosal injection of Lipo-ADR and 8.44 micrograms.day/g after i.v. administration of F-ADR. The targeting index of the regional lymph nodes, defined as the ratio of the AUC after gastric submucosal injection of Lipo-ADR to the AUC after i.v. administration of F-ADR, was 10.1. Gastric submucosal injection of Lipo-ADR enhanced lymph node-specific delivery of ADR compared with i.v. administration of F-ADR. The targeting index was 0.47 for the heart, 0.25 for the bone marrow, and 0.41 for the spleen, indicating that gastric submucosal injection of Lipo-ADR reduced delivery of ADR to these organs, as compared with i.v. administration of F-ADR. These data demonstrate that gastric submucosal injection of Lipo-ADR is well suited for specific delivery of ADR to the regional lymph nodes, suggesting that this method of administration may be useful in delivering preoperative adjuvant chemotherapy for preventing gastric cancer recurrence.

[Antitumor effect of liposome-entrapped carboplatin after intraperitoneal administration in rats]

We examined the distribution in tissue and antitumor effects of freeze-dried liposome-entrapped carboplatin (Lipo-CBDCA) after intraperitoneal administration to rats bearing AH 130 tumors. Liposomes composed of egg lecithin and cholesterol were used as drug carriers. The serum concentration of platinum was decreased for a short time after the intraperitoneal administration of Lipo-CBDCA. After at least 3 hours, the serum concentration of platinum was higher with free CBDCA intraperitoneal or intravenous administration. The antitumor effects of Lipo-CBDCA were determined in rats with peritoneal dissemination due to AH 130 tumors. Intraperitoneal Lipo-CBDCA prolonged the life span of the tumor-bearing rats. No side effects of the chemotherapy were demonstrated in biochemical and histological studies in the liver, kidney, spleen and small intestine. These results indicate that intraperitoneal chemotherapy with Lipo-CBDCA may be more effective than that with free CBDCA managing in peritoneal dissemination, and may be therapeutically useful without toxic side effects.

[Efficacy of preoperative adjuvant chemotherapy using adriamycin targeting the regional lymph nodes for gastric cancer--lymph node-targeting delivery of adriamycin in rabbits]

Chemotherapy targeting the regional lymph nodes for gastric cancer may be more effective preoperatively than postoperatively since anticancer drugs can be transported to the regional lymph nodes via the lymphatic flow through the stomach. Distribution of Adriamycin (ADR) among the various organs was assessed following its intravenous injection in rabbits. The delivery index of the drug to each organ was assessed by the ratio of the area under the concentration-time curve (AUC) of each organ to the AUC of the regional lymph nodes following the intravenous administration. The delivery index was 0.14 for the stomach, 0.11 for the heart, 0.53 for bone marrow, 0.74 for the spleen, and 0.14 for the liver. These data suggest that preoperative adjuvant chemotherapy by intravenous administration of ADR may be effective in targeting ADR at the regional lymph nodes. Tissue ADR concentrations in the regional lymph nodes were assessed following gastric submucosal administration of ADR in rabbits. The targeting index for the regional lymph nodes was 8.20, measured by the ratio of AUC following a gastric submucosal injection to AUC after the intravenous injection of ADR. This suggests that it may be possible to selectively target chemotherapy to regional lymph nodes by employing a gastric submucosal administration of ADR.

[Endoscopic injection of liposomal adriamycin targeting lymph node metastasis of gastric cancer]

Gastric submucosal injection of 5 mg liposomal adriamycin (L-ADM) close to the main gastric cancer tumor was done in 15 patients by endoscopy. This approach was based on the idea that preoperative adjuvant chemotherapy targeting lymph node metastasis in patients with gastric cancer may be effective for prevention of lymph node recurrence. ADM concentrations in the regional lymph nodes were assessed and compared with those in patients who were administered 5 mg of free adriamycin (F-ADM) i.v. preoperatively. ADM concentrations in Group 7 lymph nodes (according to the General Rules for Gastric Cancer Study) were: After 2 days; 7.21 +/- 5.98 micrograms/g (n = 2) in the L-ADM group and 0.59 +/- 0.23 micrograms/g (n = 3) in the F-ADM group. After 4 days; 4.93 +/- 3.93 micrograms/g (n = 2) in the L-ADM group and 0.36 +/- 0.0 micrograms/g (n = 2) in the F-ADM group. After 6 days; 2.08 +/- 0.49 micrograms/g (n = 2) in the L-ADM group and 0.05 +/- 0.05 micrograms/g (n = 3) in the F-ADM group. L-ADM group: those who had L-ADM injected into the side of the lesser curvature of the stomach. F-ADM group: those who had F-ADM administered i.v. These data demonstrate that gastric submucosal injection of L-ADM is well suited for specific delivery to the regional lymph nodes, suggesting that this type of administration may prevent lymph node recurrence of gastric cancer by targeting lymph node metastasis.

[Clinical application of chemotherapy via the portal vein with liposome-encapsulated adriamycin in inoperable metastatic liver cancer]

We studied the effects of liposome-entrapped adriamycin (L-ADM) administered via the portal vein and the clinical application of this treatment in the therapy and inhibition of liver metastasis, experimentally and clinically. Liposomes composed of egg phosphatidylcholine (cholesterol 50 mol%) were used as drug carriers. We examined the distribution in tissues and antitumor effect of freeze-dried L-ADM administered via the portal vein to rabbits bearing VX2 tumors. The liver concentration of ADM increased after delivery and cardiac uptake decreased compared with free drug treatment. The life span was prolonged by L-ADM treatment compared with the control group and the free ADM group. This L-ADM administration was confirmed to be safe and revealed a decrease in the heart toxicities compared with free adriamycin. Nineteen cases were studied from Jan. 1986 to May 1991 via the portal vein and the clinical effects were evaluated. From Mar. 1988 to date, 10 cases were treated with L-ADM (20-30 mg every 2 weeks/body) in patients with inoperable cases using subcutaneously implanted reservoir. The median survival was 450 days; 275 days for colon cancer, 492 days for gastric cancer, and 1,052 days for uterine cancer (range: 136-1,152 days), compared with 141 days (range: 52-253 days) in 9 cases of historical control treated with free-ADM via the portal vein. These results suggest that chemotherapy via the portal vein with L-ADM for metastatic liver cancer may increase survival time.

Antitumor effect of liposome-entrapped adriamycin administered via the portal vein

We examined the distribution in tissues and antitumor effect of freeze-dried liposome-entrapped adriamycin (Lipo-ADM) administered via the portal vein to rabbits bearing VX2 tumors. Liposomes composed of egg phosphatidylcholine (cholesterol 50 mol%) were used as drug carriers. The liver concentration of ADM increased after delivery and cardiac uptake decreased compared with free drug treatment. The in vivo antitumor effect of Lipo-ADM was determined in rabbits inoculated with VX2 tumor. Repeated injections of free ADM via the portal vein prolonged the life span of tumor-bearing rabbits. The life span was further prolonged by Lipo-ADM treatment compared with the control group and the free ADM group. Histological examination revealed that the damage to the liver caused by Lipo-ADM administered via the portal vein did not differ from that observed in animals treated with free ADM. These results indicate that portal vein administration of Lipo-ADM may be more effective in dealing with liver metastases than treatment with free ADM and may be therapeutically useful without toxic side effects.