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At least 217 records · Page 12Linked to original sources
PubMed2003

Benzoquinone, the substance essential for antibacterial activity in aqueous extracts from succulent young shoots of the pear Pyrus spp.

Aqueous extracts of the tissue of succulent young shoots of the pear Pyrus spp. exhibited strong antibacterial activity against the bacterium Erwinia amylovora bv. 4. This activity was investigated quantitatively by a newly developed bioassay method. It was found that the activity changed with the age of the tissue. Extracts of the youngest leaves and stems from the shoot tops showed the strongest activity, and the activity decreased with age of the leaves and stems. The activity also changed with increase in time after preparation of the extract, increasing rapidly in the first hour after preparation, reaching a maximum at about 4 h, and then decreasing slowly. The substance essential for the antibacterial activity was isolated from the extract by steam distillation in vacuo and through charcoal powder column chromatography. It was identified as benzoquinone (2,5-cyclohexadiene-1,4-dione) by NMR-spectra, mass spectra and HPLC analysis. The phenolic metabolism from arbutin to hydroquinone and then to benzoquinone in the aqueous extracts was analyzed quantitatively by HPLC. The changes in the contents of benzoquinone in the extracts of leaves and stems with tissue aging and with increase in time after preparation of the extracts paralleled the changes in antibacterial activity as determined by the quantitative bioassay.

Aging↗
PubMed2003

Purification and characterization of two soluble acid invertase isozymes from Japanese pear fruit.

Two isozymes (AIV I and AIV II) of soluble acid invertase (EC 3.2.1.26) were purified from Japanese pear fruit through procedures including (NH(4))(2)SO(4) precipitating, DEAE-Sephacel column chromatography, Concanavalin A (ConA)-Sepharose affinity chromatography, hydroxyapatite column chromatography and Mono Q HR 5/5 column chromatography. The specific activities of purified AIV I and AIV II were 2670 and 2340 (nkat/mg protein), respectively. AIV I was a monomeric enzyme of 80 kDa, while AIV II may be also a monomeric enzyme, which is easy to be cleaved to 52 kDa and 34 kDa polypeptide during preparation by SDS-PAGE. The Km values for sucrose of AIV I and AIV II were 3.33 and 4.58 mM, respectively, and optimum pH of both enzyme activities was pH 4.5.

Chemical Precipitation↗
PubMed1999

Vacuolar H(+)-pyrophosphatase purified from pear fruit.

A vacuolar H(+)-translocating inorganic pyrophosphatase was purified from pear fruit through selective detergent treatments, Superose 6 and Mono Q column chromatography. The specific activity of the purified enzyme was 850 mumol h-1 mg protein-1. The Mr of V-PPase was 66 kDa by SDS-PAGE and the polypeptide cross-reacted with the antiserum against V-PPase of mung bean. The purified V-PPase was stimulated by potassium and inhibited by calcium and N, N'-dicyclohexylcarbodiimide.

Blotting, Western↗
PubMed2003

Weight loss associated with a daily intake of three apples or three pears among overweight women.

OBJECTIVE: We investigated the effect of fruit intake on body weight change. METHODS: Hypercholesterolemic, overweight (body mass index > 25 kg/m2), and non-smoking women, 30 to 50 y of age, were randomized to receive, free of charge, one of three dietary supplements: apples, pears, or oat cookies. Women were instructed to eat one supplement three times a day in a total of six meals a day. Participants (411 women) were recruited at a primary care center of the State University of Rio de Janeiro, Brazil. Fifty-one women had fasting blood cholesterol levels greater than 6.2 mM/L (240 mg/dL) and 49 were randomized. Subjects were instructed by a dietitian to eat a diet (55% of energy from carbohydrate, 15% from protein, and 30% from fat) to encourage weight reduction at the rate of 1 kg/mo. RESULTS: After 12 wk of follow-up, the fruit group lost 1.22 kg (95% confidence interval = 0.44-1.85), whereas the oat group had a non-significant weight loss of 0.88 kg (0.37-2.13). The difference between the two groups was statistically significant (P = 0.004). To explore further the body weight loss associated with fruit intake, we measured the ratio of glucose to insulin. A significantly greater decrease of blood glucose was observed among those who had eaten fruits compared with those who had eaten oat cookies, but the glucose:insulin ratio was not statistically different from baseline to follow-up. Adherence to the diet was high, as indicated by changes in serum triacylglycerols, total cholesterol, and reported fruit intake. Fruit intake in the oat group throughout treatment was minimal. CONCLUSIONS: Intake of fruits may contribute to weight loss.

Adult↗
PubMed2003

Influence of 1-methylcyclopropene on ripening, storage life, and volatile production by d'Anjou cv. pear fruit.

d'Anjou cv. pear fruit (Pyrus communis L.) exposed at harvest to 0, 0.42, 4.2, or 42 micromol m(-)(3) 1-methylcyclopropene (1-MCP) for 12 h at 20 degrees C were stored at 1 degrees C for up to 8 months. After storage, half of the fruit was continuously exposed to ethylene (0.45 or 4-18 mmol m(-)(3)) for 7 days at 20 degrees C. All fruit treated with 1-MCP had lower respiration and ethylene production compared to untreated controls. Fruit quality changes were delayed following 1-MCP treatment, as was development of superficial scald and peel yellowing. The duration of 1-MCP-induced responses was dependent on 1-MCP treatment concentration. When 1-MCP-treated fruit began to ripen, softening and production of volatile compounds proceeded similar to that of untreated fruit. Post-storage ethylene exposure did not consistently stimulate ripening of fruit previously treated with 1-MCP. Efficacy of ethylene treatment depended on 1-MCP concentration and storage duration.

Cyclopropanes↗
PubMed2004

Oxalate reduces calcium availability in the pads of the prickly pear cactus through formation of calcium oxalate crystals.

The pads (nopales) of the prickly pear cactus are considered to be a good source of minerals and other nutrients on the basis of compositional analysis. In this study, this analysis is taken a step further by assessing the availability of selected minerals in nopales using an in vitro digestion and dialysis method. The results obtained suggest that although nopales are enriched in a number of minerals, their tissue calcium is not freely available. Microscopic analysis, energy-dispersive X-ray microanalysis, and oxalate measurements suggest that this reduction in available calcium is a result of its sequestration in the form of calcium oxalate crystals. The issue of mineral availability in plant foods is important when the dependence of many populations around the world on plant foods as their main source of minerals and other nutrients is considered.

Biological Availability↗
PubMed2005

Distribution of betalain pigments in red blood cells after consumption of cactus pear fruits and increased resistance of the cells to ex vivo induced oxidative hemolysis in humans.

Betalain pigments are bioavailable phytochemicals recently acknowledged as natural radical scavengers. This work, which extends previous research on the postabsorbitive fate of dietary betalains, investigated the distribution of betanin and indicaxanthin in red blood cells (RBCs) isolated from healthy volunteers (n = 8), before and during the 1-8 h interval after a cactus pear fruit meal, and the potential antioxidative activity of the pigments in these cells. A peak concentration of indicaxanthin (1.03 +/- 0.2 microM) was observed in RBCs isolated at 3 h after fruit feeding, whereas the concentration at 5 h was about half, and even smaller amounts were measured at 8 h. Indicaxanthin was not detected at 1 h. Betanin (30.0 +/- 5.2 nM) was found only in RBCs isolated at 3 h from fruit feeding. In comparison with homologous RBCs before fruit ingestion, a significant delay (P < 0.05) of the onset of an ex vivo cumene hydroperoxide (cumOOH)-induced hemolysis was evident in the RBCs isolated at 3 h (33.0 +/- 4.5 min) and at 5 h (16.0 +/- 2.0 min). Neither vitamins C and E nor GSH was modified in the RBCs at any time point. Blood collected from the same volunteers after a 12-h fasting was incubated with the purified betalains in the range of 5-25 microM, to enrich the erythrocytes with either betanin or indicaxanthin, and then the cells were exposed to cumOOH. When compared to the relevant nonenriched cells, the betalain-enriched erythrocytes exhibited an enhanced resistance to the cumOOH-induced hemolysis, which was positively correlated (r (2) = 0.99) to the amount of the incorporated compound. On a micromolar basis, betanin and indicaxanthin showed a comparable effectiveness. Taken together, these findings provide evidence that human RBCs incorporate dietary betalains and support the concept that these phytochemicals may offer antioxidative protection to the cells.

Adult↗
PubMed2005

Assessment of the volatile composition of juices of apricot, peach, and pear according to two pectolytic treatments.

The behavior of volatile compounds according to two enzymatic treatments applied during the manufacture of fruit juice is described. More than 80 compounds were detected of a wide range of chemical families (alcohols, aldehydes, ketones, terpenoids, esters, norisoprenoids, ...). Theaspirane and alpha-isophoron were tentatively identified for the first time in apricot and peach fruits. The enzymes used, for extraction or clarification of fruit juices, modified the polysaccharides separated by molecular weight and the content of soluble polysaccharides. This could indicate differences in the fruit juice matrix, which could be related to observed changes in the volatile profile. In apricot, the enzymes enhanced the juice in terpenes and norisoprenoids as varietal compounds. In peach and pear, the enzymes used did not favor the amount of lactones and decadienoate esters, the character impact compounds, respectively.

Beverages↗
PubMed1999

Residue levels of ethoxyquin, imazalil, and iprodione in pears under cold-storage conditions.

A gas chromatographic method is presented for the simultaneous determination of the antiscald ethoxyquin and the fungicides imazalil and iprodione in peel and pulp of Blanquilla pears. Fruits were cold-stored in commercial chambers in normal atmosphere and in controlled atmosphere with low oxygen content (oxygen and carbon dioxide were held at 2.5% and 1.5%, respectively). The method uses gas-liquid chromatography (GLC) with an alkaline flame ionization detector (detector of N-P, NPD) and allows the detection of the mentioned compounds to minimum levels of 0.08-0.12 mg/kg in fresh fruit. With this system the evolution of residues in fruit was monitored throughout the period of cold storage. In the surveys carried out the residue levels of these compounds were found to be below the limits allowed by the legislation of European Union. For the three studied products residues in pulp are lower and disappear more quickly than in peel.

Aminoimidazole Carboxamide↗
PubMed2000

Migration of organophosphorus insecticides cyanophos and prothiofos residues from impregnated paper bags to Japanese apple-pears (Pyrus pyrifolia nakai cv. Nijisseiki).

Bags impregnated with the organophosphorus pesticides prothiofos and cyanophos in three levels were used to cover Japanese apple-pears to protect them from insects. The amounts of prothiofos residue in the bags collected 4 months after application ranged from 0 to 34% of the amounts (81, 148, and 333 microg) found in the bags prior to a bagging. The amounts of cyanophos residue in bags collected 4 months after application ranged from 11 to 29% of the amounts (335, 2860, and 3740 microg) present prior to a bagging. Amounts of prothiofos found in fruits after 4 months ranged from 0 to 0.076 ppm. Amounts of cyanophos found in fruits after 4 months ranged from 0 to 0.011 ppm. Results of the present study indicate that these two pesticides migrated from pesticide-impregnated bags to fruits during the growing season.

Food Contamination↗
PubMed1997

Effects of chilling on the expression of ethylene biosynthetic genes in Passe-Crassane pear (Pyrus communis L.) fruits.

Passe-Crassane pears require a 3-month chilling treatment at 0 degrees C to be able to produce ethylene and ripen autonomously after subsequent rewarming. The chilling treatment strongly stimulated ACC oxidase activity, and to a lesser extent ACC synthase activity. At the same time, the levels of mRNAs hybridizing to ACC synthase and ACC oxidase probes increased dramatically. Fruit stored at 18 degrees C immediately after harvest did not exhibit any of these changes, while fruit that had been previously chilled exhibited a burst of ethylene production associated with high activity of ACC oxidase and ACC synthase upon rewarming. ACC oxidase mRNA strongly accumulated in rewarmed fruits, while ACC synthase mRNA level decreased. The chilling-induced accumulation of ACC synthase and ACC oxidase transcripts was strongly reduced when ethylene action was blocked during chilling with 1-methylcyclopropene (1-MCP). Upon rewarming ACC synthase and ACC oxidase transcripts rapidly disappeared in 1-MCP-treated fruits. A five-week treatment of non-chilled fruits with the ethylene analog propylene led to increased expression of ACC oxidase and to ripening. However, ethylene synthesis, ACC synthase activity and ACC synthase mRNAs remained at very low level. Our data indicate that ACC synthase gene expression is regulated by ethylene only during, or after chilling treatment, while ACC oxidase gene expression can be induced separately by either chilling or ethylene.

Alkenes↗
PubMed2001

Seasonal occurrence of specialist and generalist insect predators of spider mites and their response to volatiles from spider-mite-infested plants in Japanese pear orchards.

In two adjacent Japanese pear orchards (orchards I and 2), we studied the seasonal occurrence of the Kanzawa spider mite. Tetranychus kanzawai, and its predators. Also the response of these predators to the volatiles from kidney bean plants infested with T kanzawai was investigated using trap boxes in orchard 1. The mite density in orchard 1 was unimodal. with one peak at the end of August. In this orchard, population development of the specialist insect predators, Scolothrips takahashii, Oligota kashmiria benefica and Stethorus japonicus was almost synchronized with that of the spider mites. These predators disappeared when the density of their prey became very low in mid-September. Both S. takahashii and O. kashmirica benefica abruptly increased in number in orchard 2 when the spider mite population in orchard 1 decreased. These results suggested that some of the predators migrated from orchard 1 to orchard 2. In this period, predator-traps with T kanzawai-infested bean plants attracted significantly more S. takahashii than traps with uninfested plants. Very few individuals of S. japonicus and O. kashimirica benefica were found in the traps, despite their abundance in orchard 1. The generalist insect predator, Orius sp., was attracted to the traps throughout the experimental period irrespective of the density of spider mites, although this predator was never observed inside the orchards.

Animals↗
PubMed2002

A pistil-specific thaumatin/PR5-like protein gene of Japanese pear (Pyrus serotina): sequence and promoter activity of the 5' region in transgenic tobacco.

The genomic clone encoding the pistil-specific thaumatin/PR5-like protein (PsTL1) was isolated from Japanese pear (Pyrus serotina). Sequence analysis showed that the genomic clone contained the 5'-flanking sequence of 2.4 kb, the 3'-flanking sequence of 648 bp and the coding region interrupted by a intron of 351 bp. A sequence motif conserved in some pistil self-incompatibility gene promoters of solanaceous and brassicaceous species was located in the 5'-flanking region of the PsTL1 gene. The 2.4 kb 5'-flanking region was fused to the GUS coding sequence and transferred to tobacco. Transgenic tobacco showed GUS activity in pistil and, at low level, in anther, but not in other floral organs and leaf. Histochemical analysis localized GUS activity to stigma, transmitting tissue, anther and pollen of transgenic tobacco.

5' Flanking Region↗
PubMed2004

Modulation of intracellular calcium concentrations and T cell activation by prickly pear polyphenols.

Opuntia ficus indica (prickly pear) polyphenolic compounds (OFPC) triggered an increase in [Ca2+]i in human Jurkat T-cell lines. Furthermore, OFPC-induced rise in [Ca2+]i was significantly curtailed in calcium-free buffer (0% Ca2+) as compared to that in 100% Ca2+ medium. Preincubation of cells with tyrphostin A9, an inhibitor of Ca2+ release-activated Ca2+ (CRAC) channels, significantly diminished the OFPC-induced sustained response on the increases in [Ca2+]i. Lanthanum and nifedipine, the respective inhibitors of voltage-dependent and L-type calcium channels, failed to curtail significantly the OFPC-induced calcium response. As OFPC still stimulated increases in [Ca2+]i in 0% Ca2+ medium, the role of intracellular calcium was investigated. Hence, addition of thapsigargin (TG), an inhibitor of Ca2+-ATPase of the endoplasmic reticulum (ER), during the OFPC-induced peak response exerted an additive effect, indicating that the mechanism of action of these two agents are different. Furthermore, U73122, an inhibitor of IP3 production, completely abolished increases in [Ca2+]i, induced by OFPC, suggesting that these polyphenols induce the production of IP3 that recruits calcium from ER pool. Polyphenolic compounds do act extracellularly as addition of fatty acid-free bovine serum albumin (BSA) significantly diminished the rise in [Ca2+]i evoked by the formers. OFPC also induced plasma membrane hyperpolarisation which was reversed by addition of BSA. OFPC were found to curtail the expression of IL-2 mRNA and T-cell blastogenesis. Together these results suggest that OFPC induce increases in [Ca2+]i via ER pool and opening of CRAC channels, and exert immunosuppressive effects in Jurkat T-cells.

Calcium↗
PubMed2001

Fingerprinting of polysaccharides attacked by hydroxyl radicals in vitro and in the cell walls of ripening pear fruit.

Hydroxyl radicals (*OH) may cause non-enzymic scission of polysaccharides in vivo, e.g. in plant cell walls and mammalian connective tissues. To provide a method for detecting the action of endogenous *OH in vivo, we investigated the products formed when polysaccharides were treated with *OH (generated in situ by ascorbate-H(2)O(2)-Cu(2+) mixtures) followed by NaB(3)H(4). Treatment with *OH increased the number of NaB(3)H(4)-reacting groups present in citrus pectin, homogalacturonan and tamarind xyloglucan. This increase is attributed partly to the formation of glycosulose and glycosulosuronic acid residues, which are then reduced back to the original (but radioactive) sugar residues and their epimers by NaB(3)H(4). The glycosulose and glycosulosuronic acid residues were stable for >16 h at 20 degrees C in ethanol or buffer (pH 4.7), but were destroyed in alkali. Driselase-digestion of the radiolabelled polysaccharides yielded characteristic patterns of (3)H-products, which included galactose and galacturonate from pectin, and isoprimeverose, galactose, glucose and arabinose from xyloglucan. Pectin yielded at least eight (3)H-labelled anionic products, separable by electrophoresis at pH 3.5. The patterns of radioactive products form useful 'fingerprints' by which *OH-attacked polysaccharides may be recognized. Applied to the cell walls of ripening pear (Pyrus communis) fruit, the method gave evidence for progressive *OH radical attack on polysaccharides during the softening process.

Cell Wall↗
PubMed1999

The clinical superiority of continuous exposure versus short-pulsed carbon dioxide laser exposures for the treatment of pearly penile papules.

Treatment of pearly penile papules was performed both with a conventional continuous-wave (CW) and a newer generation high energy pulsed carbon dioxide laser. When compared to the short pulsed laser, the CW laser, using relatively low power densities, provided superior hemostasis and improved visualization of the operative field. Despite the increase in thermal injury, wound healing was not compromised. The results of this case report support the CO2 laser in CW mode as the infrared laser treatment of choice for exophytic lesions with increased vascularity.

Adult↗
PubMed2003

Pearly penile papules: still no reason for uneasiness.

BACKGROUND: Penile lesions and pearly penile papules (PPP) are frequently found in male sexual partners of women with cervical intraepithelial neoplasia (CIN). The former have been associated with human papillomavirus (HPV). OBJECTIVES: We estimated the prevalence of PPP in male sexual partners of women with CIN, and investigated the association between PPP and flat and papular penile lesions found in these men. We further evaluated a possible association between PPP and HPV, age, and CIN grade of the female partner. METHODS: We evaluated by penoscopy the presence of HPV-associated penile lesions and PPP in 226 male sexual partners of women with CIN. HPV was tested by polymerase chain reaction-enzyme immunoassay and in situ hybridization. RESULTS: The prevalence of PPP was 34% and was not associated with the presence of penile lesions or a positive HPV test. Age and CIN grade of the female partner were not related to the presence of PPP. CONCLUSION: The prevalence of PPP in male sexual partners of women with CIN is comparable with the prevalence described in men of more diverse populations. Our data do not support a causative role for HPV in the genesis of PPP.

Adult↗
PubMed1994

Molecular cloning of a gene encoding an arabinogalactan-protein from pear (Pyrus communis) cell suspension culture.

Arabinogalactan-proteins (AGPs) are proteoglycans containing a high proportion of carbohydrate (typically > 90%) linked to a protein backbone rich in hydroxyproline (Hyp), Ala, Ser, and Thr. They are widely distributed in plants and may play a role in development. The structure of the carbohydrate of some AGPs is known in detail but information regarding the protein backbone is restricted to a few peptide sequences. Here we report isolation and partial amino acid sequencing of the protein backbone of an AGP. This AGP is a member of one of four major groups of AGPs isolated from the filtrate of pear cell suspension culture. A cDNA encoding this protein backbone (145 amino acids) was cloned; the deduced protein is rich in Hyp, Ala, Ser, and Thr, which together account for > 75% of total residues. It has three domains, an N-terminal secretion signal, a central hydrophilic domain containing all of the Pro residues, and a hydrophobic C-terminal domain that is predicted to be a transmembrane helix. Approximately 93% of the Pro residues are hydroxylated and hence are potential sites for glycosylation.

Amino Acid Sequence↗