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PubMed2002

Determination of total phenols in environmental wastewater by flow-injection analysis with a biamperometric detector.

A flow injection (FI) method with a biamperometric detector, based on the biamperometry for an irreversible redox couple, is described for the determination of phenols in environmental wastewater. The method relies on coupling of the oxidation of phenols at one platinum-wire electrode with the reduction of MnO4- at another platinum wire electrode to enable biamperometric detection with an applied potential difference of 0 V. The linear dynamic range for the dependence of current on phenol concentration was from 1.0 x 10(-6) to 1.0 x 10(-4) mol L(-1), with a detection limit of 4.0 x 10(-7) mol L(-1) (signal-to-noise ratio, S/N=3). In comparison with the 4-aminoantipyrine (4-AAP) standard method and the 3-methyl-2-benzothiazoline hydrazone (MBTH) method the proposed method can be used to detect many para-substituted phenols that do not react with 4-AAP and MBTH, and response factors are higher for most of the phenols tested. The method, which is simple, economic, and rapid (180 samples h(-1)), has been applied to the analysis of four wastewater samples. The results obtained were compared with those from 4-AAP method. The recoveries obtained by adding phenol standards to samples ranged from 94.3 to 105.2% with a standard deviation of 3.6%.

Electrochemistry↗
PubMed2004

Grr1p is required for transcriptional induction of amino acid permease genes and proper transcriptional regulation of genes in carbon metabolism of Saccharomyces cerevisiae.

The F-box protein Grr1p is involved in cell cycle regulation, glucose repression and transcriptional induction of the amino acid permease (AAP) gene AGP1. We investigated the role of Grr1p in amino acid-mediated induction of AAP genes by performing batch cultivations with a wild-type strain and a grr1Delta strain and adding citrulline in the exponential phase. Whole-genome transcription analyses were performed on samples from each cultivation, both immediately before and 30 min after citrulline addition. Transcriptional induction of the AAP genes AGP1, BAP2, BAP3, DIP5, GNP1 and TAT1 is fully dependent on Grr1p. Comparison of the grr1Delta strain with the reference strain in the absence of citrulline revealed that GRR1 disruption leads to increased transcription of numerous genes. These encode enzymes in the tricarboxylic acid cycle, the pentose-phosphate pathway and both glucose and starch metabolism. Promoter analysis showed that many of the genes with increased transcription display Mig1p- and/or Msn2p/Msn4p-binding sites. Increased expression of glucose-repressed genes in the grr1Delta strain may be explained by the reduced expression of the hexose transporter genes HXT1, HXT2, HXT3 and HXT4 and a subsequent lowering of the glucose uptake; and the effect of GRR1 deletion on general carbon metabolism may therefore be indirect. Finally, none of the genes known to be primarily involved in cell cycle regulation displayed different expression levels in the grr1Delta cells as compared with the reference strain, suggesting that the role of Grr1p in cell cycle regulation does not include any transcriptional component.

Amino Acid Transport Systems↗
PubMed2006

The high-resolution structures of the neutral and the low pH crystals of aminopeptidase from Aeromonas proteolytica.

The aminopeptidase from Aeromonas proteolytica (AAP) contains two zinc ions in the active site and catalyzes the degradation of peptides. Herein we report the crystal structures of AAP at 0.95-A resolution at neutral pH and at 1.24-A resolution at low pH. The combination of these structures allowed the precise modeling of atomic positions, the identification of the metal bridging oxygen species, and insight into the physical properties of the metal ions. On the basis of these structures, a new putative catalytic mechanism is proposed for AAP that is likely relevant to all binuclear metalloproteases.

Aeromonas↗
PubMed2007

Zea mays: benzoxazolinone detoxification under sulfur deficiency conditions--a complex allelopathic alliance including endophytic Fusarium verticillioides.

Benzoxazolinone detoxification is similar in plants grown under sulfur deficiency conditions and in control plants grown with an optimal S supply. However, when S-deficient plants were treated with metolachlor before benzoxazolin-2(3H)-one (BOA) incubation, detoxification was reduced, as indicated by a lower accumulation of the detoxification products BOA-6-O-glucoside and glucoside carbamate and by a loss of BOA-6-OH glucosyltransfease activity. Root colonizing microorganisms and the endophytic fungus Fusarium verticillioides participated in benzoxazolinone detoxification by converting the compound to 2-acetamidophenol (AAP) or O-hydroxyphenyl malonamic acid (OHPMA), a process accompanied by the appearance of phenoxazinone. Maize roots, however, absorbed AAP and OHPMA only in traces. Absorbed traces of OHPMA stimulated maize radicle growth, and traces of AAP stimulated cress. Phenoxazinone inhibited the growth of cress radicles at concentrations higher than 500 microM, whereas maize radicles were hardly affected. F. verticillioides did not convert benzoxazolinone to any known microbial degradation product when the medium of maize seedlings was inoculated with the fungus under sterile condition. Plant-fungus interactions seem to be important in plant survival of allelopathic attacks. This study points to a complicated network of allelopathic interactions that are influenced by biotic and abiotic factors, including herbicides.

Acetamides↗
PubMed1996

Low molecular mass proteins and urinary enzymes in amniotic fluid of healthy pregnant women at progressive stages of gestation.

OBJECTIVES: Amniotic fluid alpha1-microglobulin (alpha1-m) and beta2-microglobulin (beta2-m) levels, as well as N-acetyl-beta-D-glucosaminidase (NAG) and alanine aminopeptidase (AAP) activities, were measured in the course of uncomplicated pregnancies to assess their variations as gestation progresses. DESIGN AND METHODS: Samples were obtained from 141 healthy pregnant women divided into three groups on the basis of gestational stage. Quantitative estimation of proteins was performed immunometrically and enzyme activities were determined spectrophotometrically. RESULTS: It was found that, during pregnancy, alpha1-m and beta2-m concentrations as well as AAP activity significantly decrease, although their reduction patterns vary. Controversial results were found for NAG activity: the normalization of values for amniotic fluid creatinine significantly changed the reduction pattern of this enzyme. No statistically significant differences were found between male and female fetuses for amniotic fluid values of the biochemical substances studied. CONCLUSIONS: The behavior observed for alpha1-m, beta2-m, and AAP might be linked to the progressive development and maturation of fetal renal tubular function. Amniotic fluid total NAG activity seems not to depend only on fetal urinary excretion.

Acetylglucosaminidase↗
PubMed1987

Aflatoxin B1 and acetaminophen induce different cytoskeletal responses during prelethal hepatocyte injury.

Primary monolayer cultures of adult rat hepatocytes exposed to the hepatocarcinogen aflatoxin B1 (AFB1) undergo a characteristic prelethal cytomorphological change that is distinct from their response to the necrogenic noncarcinogenic hepatotoxin, acetaminophen (AAP). Since changes in cell shape are mediated, at least in part, by the F-actin cytoskeleton, we designed experiments to study early prelethal alterations in the distribution of actin microfilaments in monolayer rat hepatocytes exposed to AFB1 (100 microM) or AAP (16 mM). Using rhodamine-phalloidin fluorescence microscopy, we observed that normal hepatocytes showed a submembranous F-actin distribution with focal short microfilaments extending into filopodia along the periphery of the cell. Hepatocytes exposed to AFB1 for several hours exhibited retraction of their cytoplasm within a prominent circumferential peripheral band of F-actin microfilament bundles. Retraction of focal areas of peripheral cytoplasm was associated with an increased prominence of the radial F-actin-containing filopodia. Subsequently, there appeared peripheral blebs containing very little F-actin. Hepatocytes exposed to equivalently lethal concentrations of AAP initially remained structurally normal. After several hours, the cells exhibited a prominent polar aggregate of short microfilament bundles without the formation of blebs. Both the blebbing and the polar aggregation of F-actin bundles occurred prior to cell death as shown by lactate dehydrogenase release and trypan blue exclusion. These studies support the hypothesis that the lethal effects of these two agents may occur by different biological mechanisms that are associated with remarkably distinct prelethal cytoskeletal responses.

Acetaminophen↗
PubMed1994

Tubular proteins and enzyme content in the amniotic fluid.

Amniotic fluid is the product of many substances and fetal urine is considered to be one of the principal components. Only a few reports have been published describing the concentration of microglobulins and urinary enzymes in the amniotic fluid. We determined the levels of alpha 1-m, beta 2-m, AAP and NAG, in 154 samples of amniotic fluid (103 early determinations and 51 late determinations) as a function of gestational age. We observed a statistically significant decrease in concentration of alpha 1-m (P < 0.001), beta 2-m (P < 0.01) and AAP (P < 0.001) when early and late amniotic fluid samples were compared. A statistically significant increase of NAG (P < 0.01) and creatinine (P < 0.01) was also found. A significant correlation was observed between alpha 1-m and beta 2-m, and between AAP and NAG, respectively. The potential role of urinary enzyme and microglobulin determination in amniotic fluid as an index of fetal kidney development, is discussed.

Acetylglucosaminidase↗
PubMed1995

Age-dependent enzymuria, proteinuria and changes in renal blood flow and glomerular filtration rate in rats.

The time course of urinary excretion of two enzymatic indicators of renal damage, N-acetyl-beta-D-glucosaminidase (NAG) and alanine aminopeptidase (AAP) was measured in female Wistar rats at different ages. NAG and AAP are localized at different sites of the nephron and are released into the urine when kidney damage occurs. Total protein flow, urinary volume and creatinine flow were also determined. In a parallel experiment, the effect of aging on renal blood flow (RBF) and glomerular filtration rate (GFR) was examined in young (1.5-month) adult (3-month) and elderly (20-month) female rats. Clearance following a single injection of [131I]o-iodohippurate (hippuran, OIH) was used for the measurement of effective RBF and as an index of tubular cell function. [125I]Iothalamate (IOT) clearance was used to measure GFR. With advancing age, an increase in NAG and AAP urinary flow appeared. The increases in protein excretion were greater than and previous to those of enzyme excretion. It is shown that absolute RBF and GFR (ml/min) in old rats are greater than in young or adult animals. When absolute RBF or GFR was divided by kidney weight (ml/min/g) no clearance changes appeared in any age group studied; only when clearance was expressed in relation to body weight (ml/min/100 g), a decrease in RBF and GFR was evidenced. This indicates that the rate of increase of both RBF and GFR with age is similar to that of kidney weight and lower than that of body weight. The present findings indicate that urinary markers of renal injury increase with age, whereas GFR and RBF only decrease when expressed as clearance related to body weight.

Aging↗
PubMed1980

Formation of mutagenic derivatives from nitrite and two primary amines.

Sodium nitrite and two primary aromatic amines, viz. amino antipyrine (AAP) and aniline, were preincubated in vitro with human gastric juice. The resulting derivatives -- presumably diazonium salts -- were directly mutagenic in the Salmonella test. The mutagenic response was more pronounced in the case of AAP, while toxic effects narrowed the range of activity of the aniline derivative. These patterns are consistent with the findings of independent colorimetric analyses, showing that the AAP derivative is more stable at 37 degrees C than the aniline derivative.

Ampyrone↗
PubMed1984

Protection by glycerol of urinary L-alanine aminopeptidase activity from freezing and thawing inactivation.

L-Alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG) activities in urine are sensitive indicators of renal damage. However, urinary AAP loses its activity during storage in the frozen state. This study proposes a method for preventing the inactivation of AAP by adding glycerol to a final concentration of 10% to a urine sample before freezing and thawing. This study also showed that NAG is stable to freezing and thawing and is not affected by addition of glycerol.

Acetylglucosaminidase↗
PubMedDate not supplied

Effects of nicotine and ethanol on rat atrial membrane potentials.

The purpose of this research was to study the effects of nicotine and ethanol, alone and in combination, on cardiac membrane potentials (MP). Rat atrial preparations driven at 5 Hz were superfused with Tyrode's solution (37 degrees C) while recording MP with intracellular microelectrodes. Nicotine concentrations below and including 6.2 x 10(-5) M did not affect MP. Within 15 s, nicotine 3.1 x 10(-3) M shortened the action potential duration (APD) and depressed the overshoot of the action potential (OS). This action was blocked by atropine. After 3 min, nicotine prolonged the APD and depressed Vmax of phase O, OS and the amplitude of the action potential (AAP), without affecting the resting membrane potential (RMP). Nifedipine blocked the depression of the OS while tetraethylammonium chloride blocked the prolongation of the APD. Acute exposure to ethanol depressed OS and AAP and shortened APD, but it did not affect RMP or Vmax of phase O. When nicotine and ethanol were administered simultaneously, the APD-prolonging effects of nicotine prevailed. The influence of chronic ethanol ingestion on the acute action of nicotine and/or ethanol was studied in rats pair-fed a liquid diet with (ER) or without (NR) ethanol (35% of total caloric intake) for 24 weeks. Chronic ethanol ingestion accentuated the depressant effect of nicotine 3.1 x 10(-3) M on OS and AAP, but it did not modify the APD-prolonging action of nicotine. The same results were observed when ER and NR were exposed to nicotine and ethanol simultaneously.

Action Potentials↗
PubMed1993

The effect of interleukin 1 alpha on acetaminophen-induced hepatotoxicity.

The protective effect of interleukin 1 alpha (IL-1 alpha) in mice with acetaminophen (AAP)-induced hepatitis was investigated. IL-1 alpha had a significant protective effect if given 2 or more hours (up to 24 hours) before AAP; it significantly reduced mortality of mice and decreased serum transaminase level. The maximal effect was obtained with the dose of 1000 U (166 ng/kg) IL-1 alpha. Pretreatment with IL-1 significantly increased the synthesis of prostaglandin E2 (PGE2) in samples of liver tissue from AAP-treated mice, but had no effect on the synthesis of leukotriene C4 (LTC4). Pretreatment with indomethacin (IMC) did not abrogate significantly the protective effect of IL-1. Thus, the hepatoprotective effect of IL-1 alpha can not be entirely explained by the stimulation of prostaglandin (PG) synthesis.

Acetaminophen↗
PubMed1994

Pediatricians' views of access to health services for adolescents.

PURPOSE: The American Academy of Pediatrics (AAP) carried out a member survey to measure pediatricians' views of parental permission and notification for selected health services for two age groups of adolescents, the 13 to 15 year olds and the 16 to 17 year olds. METHODS: Through an AAP Periodic Survey, a sample of 1000 members of the AAP were sent questionnaires to fill out and return. The response rate was 77%. RESULTS: The majority of pediatricians in all groups examined believed parental permission and notification were important for general medical and surgical care. But for most other types of care delineated, related to substance abuse and sexuality, most pediatricians did not believe parental permission should be required, except for requests for abortion for 13-15 year olds. For several types of care most pediatricians believed parental notification should be required for 13-15 year olds. Older pediatricians, male pediatricians, and self-employed pediatricians were more apt to support both parental permission and notification for all types of care. When age, gender and self versus not self-employed were introduced together through a logistic regression procedure differences in views were accounted for by self versus not self-employed, and age and gender had no additional impact. CONCLUSIONS: Most pediatricians supported the right of minors to seek care without parental permission for care related to substance abuse and sexuality. The majority were less likely to grant confidentiality to adolescents, particularly those 13 to 15 years.

Adolescent↗
PubMed2006

Protease (PrA and PrB) and prolyl and arginyl aminopeptidase activities from Debaryomyces hansenii as a function of growth phase and nutrient sources.

The effects of nutrient sources and growth phase of Debaryomyces hansenii on the protease (PrA and PrB) and aminopeptidase (prolyl-[PAP] and arginyl-[AAP] aminopeptidases) activities were investigated. These activities were also monitored during growth on a whole sarcoplasmic muscle protein extract (WSPE) and on an equivalent medium but free of compounds under 10 kDa (SPE>10 kDa). The levels of specific protease and aminopeptidase activities were higher when cells were grown in urea and dipeptides than when grown in either ammonium or free amino acids as nitrogen sources. The level of each aminopeptidase (PAP or AAP) activity was preferentially induced by its own substrate (ProLeu or LysAla), suggesting a role in the utilization of exogenous peptides. Higher specific activities for all proteolytic enzymes were detected when using acetate as carbon source. The time course experiments carried out on urea or sarcoplasmic protein-containing media revealed an increase in all activities during transition and advanced stages of stationary phase of growth. In muscle protein extracts, the absence of low molecular mass nutrients (SPE>10 kDa) initially induced the production of PrA, PrB, and AAP activities, possibly involved in the breakdown of muscle oligopeptides.

Aminopeptidases↗
PubMed2005

Application of Eudragit RS to thermo-sensitive drug delivery systems: II. Effect of temperature on drug permeability through membrane consisting of Eudragit RS/PEG 400 blend polymers.

The Eudragit RS and polyethylene glycol 400 (PEG 400) blend polymer (EPG) membranes were prepared by the solvent casting method to pioneer a novel application of Eudragit RS to a thermo-sensitive material. The EPG membranes containing 2.5-10% PEG 400 (2.5-10% EPG) showed the glass transition temperatures (Tgs) around the body temperature (32-42 degrees C). Drug permeation studies through the EPG membranes were carried out using acetaminophen (AAP) and aminopyrine (AMP) as the model drugs. The permeability of AAP and AMP through the EPG membranes has been shown to be a discontinuous function of temperature, that is, their permeability increased steeply above the Tg of the membranes. The amount of AMP permeated at 42 degrees C was nearly eight times as much as that at 36 degrees C. Arrhenius plots of the steady-state permeability coefficient (P) of AAP indicated two straight lines that intersect at the Tg of the 10% EPG membrane. In the water uptake study for the 10% EPG membrane, the degree of the swelling for the membrane tended to increase with increasing temperature above the Tg of the membrane. The thermo-sensitive permeation mechanism for the EPG membranes might be based on the structure change of the membranes caused by the glass transition, so that the membranes could absorb more water. Considering the high biological safety of Eudragit RS and PEG 400, the EPG membranes might be used to develop a novel thermo-sensitive drug delivery system.

Acrylic Resins↗
PubMed2004

Repair of mycotic aortic pseudoaneurysm with a stent graft using transesophageal echocardiography.

A 54-year-old man who underwent uneventful orthotopic heart transplantation 1 year previously had low-grade fever and dyspnea. Imaging studies revealed an ascending aortic pseudoaneurysm (AAP), which was repaired with a 5-mm polyester patch, with circulatory arrest and cardiopulmonary bypass. Intraoperative cultures of the AAP grew methicillin-resistant Staphylococcus aureus, and the pseudoaneurysm recurred after 6 weeks despite intravenously administered antibiotic therapy. A 28.5-mm x 3.3-cm Gore Excluder aortic cuff was deployed in the ascending aorta through a left axillary artery cutdown with use of combined transesophageal echocardiography and fluoroscopy. In addition, controlled hypotension and asystole were established with administration of adenosine to facilitate precise device deployment. Postoperative imaging with transesophageal echocardiography and magnetic resonance angiography revealed complete resolution of the AAP, and the patient had done well at 7-month follow-up. Treatment of a mycotic aortic pseudoaneurysm with an endoprosthesis in a patient without other treatment alternatives can be performed safely, with acceptable short-term results.

Aneurysm, False↗
PubMed2005

Ribosome occupancy of the yeast CPA1 upstream open reading frame termination codon modulates nonsense-mediated mRNA decay.

Saccharomyces cerevisiae CPA1 mRNA contains an upstream open reading frame (uORF) encoding the arginine attenuator peptide (AAP). Negative translational regulation of CPA1 occurs when the nascent AAP responds to arginine (Arg) by stalling ribosomes at the uORF termination codon. CPA1 expression is also controlled by nonsense-mediated mRNA decay (NMD). Using wild-type and decay-defective strains expressing CPA1-LUC, we determined how this uORF contributes to NMD control. Arg addition to media rapidly destabilized the CPA1 transcript in wild-type but not upf1delta cells. The wild-type uORF exerted translational control and induced NMD of CPA1-LUC; the mutated D13N uORF, which eliminates stalling and regulation, did not. Thus, regulation by NMD was not governed simply by ribosomes encountering the uORF terminator but appeared dependent on the AAP's ribosome-stalling ability. Improving the D13N uORF initiation context also promoted NMD. Hence, NMD appears to be triggered by increased ribosomal occupancy of the uORF termination codon.

Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzin↗
PubMed2006

Purification, characterization and cloning of antiviral/ribosome inactivating protein from Amaranthus tricolor leaves.

An antiviral protein (AVP), imparting high level of resistance against sunnhemp rosette virus (SRV) was purified from the dried leaves of Amaranthus tricolor. The purified protein (AAP-27) exhibited approximately 98% inhibition of local lesion formation at a concentration range of approximately 30 microg ml(-1). The protein was found to be highly basic glycoprotein monomer (pI approximately 9.8) of Mr 27 kDa, with neutral sugar content of 4%. The purified protein exhibited N-glycosidase and RNase activities. We have also isolated full-length cDNA clone, encoding this protein designated as A. tricolor antiviral protein-1 (AAP-1). Two primers, one designed on the basis of N-terminal sequence of the purified protein and the other from the conserved active peptides of other AVPs/RIPs were used for PCR amplification of double stranded cDNA, isolated from the leaves of A. tricolor. The amplified fragment was used as a probe for library screening. The isolated full-length cDNA consisted of 1058 nucleotides with an open reading frame encoding a polypeptide of 297 amino acids. The deduced amino acid sequence of AAP-1 has a putative active domain conserved in other AVPs/RIPs and shows varying homology to the RIPs from other plant species.

Amaranthus↗