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Biomedical subjects

A Esen

Publications and source records attributed to A Esen.

At least 19 recordsLinked to original sources
PubMed2006

Successful treatment of a child with fulminant liver failure and coma due to Amanita phalloides poisoning using urgent liver transplantation.

Intoxication due to eating wild mushrooms presents with a variety of signs, ranging from mild diarrhea to severe organ failure. We present the case of an 11-year-old boy with fulminant liver failure and hepatic coma due to Amanita phalloides poisoning treated with an urgent pediatric orthotopic liver transplantation. Successful treatment of patients with fulminant liver failure and hepatic coma caused by Amanita phalloides poisoning is possible using urgent orthotopic liver transplantation when conservative medical treatment modalities are ineffective.

Amanita↗
PubMed2006

Efficacy of tadalafil in Egyptian and Turkish men with erectile dysfunction.

A randomised, double-blind, parallel, placebo-controlled, 12-week study was carried out to evaluate the efficacy and safety of 20-mg tadalafil taken 'as needed' in a population of men with erectile dysfunction (ED) from Egypt and Turkey. One hundred and thirty-two patients were randomised in this study. Tadalafil was superior to placebo on all three co-primary efficacy end points. The mean change from baseline for the erectile function domain of the International Index of Erectile Function was 9.3 +/- 0.8 for the tadalafil group and 2.3 +/- 1.6 for the placebo group. Tadalafil-treated patients reported a significantly greater improvement in the mean percentage of successful penetrations (tadalafil: 34.5 +/- 4.1; placebo: -4.6 +/- 8.1) and successful intercourse attempts (tadalafil: 52.2 +/- 3.8; placebo: 16.8 +/- 7.8) than placebo-treated patients as measured by the Sexual Encounter Profile. Tadalafil was generally well tolerated with 82% of adverse events being mild in severity. Tadalafil 20-mg taken 'as needed' significantly improved the erectile function in Egyptian and Turkish men with ED.

Adolescent↗
PubMed2005

Erectile dysfunction prevalence and sexual function status in patients with chronic obstructive pulmonary disease.

PURPOSE: We determined sexual status and erectile dysfunction (ED) in outpatients with chronic obstructive pulmonary disease (COPD). MATERIALS AND METHODS: Between October 2002 and June 2003 a total of 60 successive outpatients with COPD enrolled in the study with written informed consent. Patients completed International Index of Erectile Function (IIEF) and Duke Activity Status Index questionnaires. They also underwent physical examination including urogenital examination and pulmonary assessment with spirometry, 6-minute walk test and arterial blood sample. COPD severity was determined according to Global Initiative for Chronic Obstructive Lung Disease criteria. RESULTS: After exclusion criteria 53 patients were assessed for statistical analysis. Mean patient age was 63.4 +/- 7.3 years. COPD severity in these patients was mild in 13.2%, moderate in 34%, severe in 49.1% and very severe in 3.8%. Nearly half of the patients (49%) had no comorbid disease for ED and the most common comorbid disease was hypertension (34%). According to the erectile function domain of IIEF 75.5% of patients were found to have ED with varying degrees (severe 28.3%, moderate 11.3%, mild to moderate 15.1% and mild 20.8%). Mean scores of all IIEF domains except sexual desire decreased with the increasing disease severity. A correlation was determined between severity and physical restrictions of COPD, and ED severity. CONCLUSIONS: The limitation of physical activity due to COPD also diminishes the sexual function of patients. This point must be kept in mind in the evaluation of patients with COPD.

Aged↗
PubMed2004

An evaluation of nursing care in cancer patients.

The aim of the present study was to identify what hospitalized cancer patients expect from nurses in terms of the care they receive. The specific aims of this study were: (i) to identify those individuals to whom the patients felt closest in the hospital setting and (ii) to evaluate nurses' management of cancer patients during their stay in the hospital. The sample included patients hospitalized at Ege University Hospital and Suat Seren District Hospital, Izmir, Turkey. We found significant differences between the scores of satisfaction and dissatisfaction and gender age, education, occupation, type of cancer and the mode of treatment (p < 0.05). The majority of the cancer patients reported that nursing management was unsatisfactory. Some demographic factors such as cultural and social status affected patients' expectations.

Cohort Studies↗
PubMed2001

Crystal structure of a monocotyledon (maize ZMGlu1) beta-glucosidase and a model of its complex with p-nitrophenyl beta-D-thioglucoside.

The maize beta-glucosidase isoenzymes ZMGlu1 and ZMGlu2 hydrolyse the abundant natural substrate DIMBOAGlc (2-O-beta-D-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one), whose aglycone DIMBOA (2,4-hydroxy-7-methoxy-1,4-benzoxazin-3-one) is the major defence chemical protecting seedlings and young plant parts against herbivores and other pests. The two isoenzymes hydrolyse DIMBOAGlc with similar kinetics but differ from each other and their sorghum homologues with respect to specificity towards other substrates. To gain insights into the mechanism of substrate (i.e. aglycone) specificity between the two maize isoenzymes and their sorghum homologues, ZMGlu1 was produced in Escherichia coli, purified, crystallized and its structure solved at 2.5 Angstrom resolution by X-ray crystallography. In addition, the complex of ZMGlu1 with the non-hydrolysable inhibitor p-nitrophenyl beta-D-thioglucoside was crystallized and, based on the partial electron density, a model for the inhibitor molecule within the active site is proposed. The inhibitor is located in a slot-like active site where its aromatic aglycone is held by stacking interactions with Trp-378. Whereas some of the atoms on the non-reducing end of the glucose moiety can be modelled on the basis of the electron density, most of the inhibitor atoms are highly disordered. This is attributed to the requirement of the enzyme to accommodate two different species, namely the substrate in its ground state and in its distorted conformation, for catalysis.

Amino Acid Sequence↗
PubMed2000

The mechanism of substrate (aglycone) specificity in beta -glucosidases is revealed by crystal structures of mutant maize beta -glucosidase-DIMBOA, -DIMBOAGlc, and -dhurrin complexes.

The mechanism and the site of substrate (i.e., aglycone) recognition and specificity were investigated in maize beta-glucosidase (Glu1) by x-ray crystallography by using crystals of a catalytically inactive mutant (Glu1E191D) in complex with the natural substrate 2-O-beta-d-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOAGlc), the free aglycone DIMBOA, and competitive inhibitor para-hydroxy-S-mandelonitrile beta-glucoside (dhurrin). The structures of these complexes and of the free enzyme were solved at 2.1-, 2.1-, 2.0-, and 2.2-A resolution, respectively. The structural data from the complexes allowed us to visualize an intact substrate, free aglycone, or a competitive inhibitor in the slot-like active site of a beta-glucosidase. These data show that the aglycone moiety of the substrate is sandwiched between W378 on one side and F198, F205, and F466 on the other. Thus, specific conformations of these four hydrophobic amino acids and the shape of the aglycone-binding site they form determine aglycone recognition and substrate specificity in Glu1. In addition to these four residues, A467 interacts with the 7-methoxy group of DIMBOA. All residues but W378 are variable among beta-glucosidases that differ in substrate specificity, supporting the conclusion that these sites are the basis of aglycone recognition and binding (i.e., substrate specificity) in beta-glucosidases. The data also provide a plausible explanation for the competitive binding of dhurrin to maize beta-glucosidases with high affinity without being hydrolyzed.

Amino Acid Sequence↗
PubMed2000

Identification of beta-glucosidase aggregating factor (BGAF) and mapping of BGAF binding regions on Maize beta -glucosidase.

In certain maize genotypes (nulls), beta-glucosidase does not enter the gel and therefore cannot be detected on zymograms. Such genotypes were initially thought to be homozygous for a null allele at the glu1 gene. We have shown that a beta-glucosidase aggregating factor (BGAF) is responsible for the null phenotype, and it specifically interacts with maize beta-glucosidases and forms large insoluble aggregates. To understand the mechanism of the beta-glucosidase-BGAF interaction, we constructed chimeric enzymes by domain swapping between the maize beta-glucosidase isozymes Glu1 and Gu2, to which BGAF binds, and the sorghum beta-glucosidase (dhurrinase) isozyme Dhr1, to which BGAF does not bind. The results of binding assays with 12 different chimeric enzymes showed that an N-terminal region (Glu(50)-Val(145)) and an extreme C-terminal region (Phe(466)-Ala(512)) together form the BGAF binding site on the enzyme surface. In addition, we purified BGAF, determined its N-terminal sequence, amplified the BGAF cDNA by reverse transcriptase-polymerase chain reaction, expressed it in Escherichia coli, and showed that it encodes a protein whose binding and immunological properties are identical to the native BGAF isolated from maize tissues. A data base search revealed that BGAF is a member of the jasmonite-induced protein family. Interestingly, the deduced BGAF sequence contained an octapeptide sequence (G(P/R)WGGSGG) repeated twice. Each of these repeat units is postulated to be involved in forming a site for binding to maize beta-glucosidases and thus provides a plausible explanation for the divalent function of BGAF predicted from binding assays.

Amino Acid Sequence↗
PubMed2000

The aglycone specificity-determining sites are different in 2, 4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA)-glucosidase (Maize beta -glucosidase) and dhurrinase (Sorghum beta -glucosidase).

The maize beta-glucosidase isozyme Glu1 hydrolyzes a broad spectrum of substrates in addition to its natural substrate DIMBOAGlc (2-O-beta-d-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxazin-3-on e), whereas the sorghum beta-glucosidase isozyme Dhr1 hydrolyzes exclusively its natural substrate dhurrin (p-hydroxy-(S)-mandelonitrile-beta-d-glucose). To study the mechanism of substrate specificity further, eight chimeric beta-glucosidases were constructed by replacing peptide sequences within the C-terminal region of Glu1 with the homologous peptide sequences of Dhr1 or vice versa, where the two enzymes differ by 4 to 22 amino acid substitutions, depending on the length of the swapped regions. Five Glu1/Dhr1 chimeras hydrolyzed substrates that are hydrolyzed by both parental enzymes, including dhurrin, which is not hydrolyzed by Glu1. In contrast, three Dhr1/Glu1 chimeras hydrolyzed only dhurrin but with lower catalytic efficiency than Dhr1. Additional domain-swapping within the C-terminal domain of Glu1 showed that replacing the peptide (466)FAGFTERY(473) of Glu1 with the homologous peptide (462)SSGYTERF(469) of Dhr1 or replacing the peptide (481)NNNCTRYMKE(490) in Glu1 with the homologous peptide (477)ENGCERTMKR(486) of Dhr1 was sufficient to confer to Glu1 the ability to hydrolyze dhurrin. Data from various reciprocal chimeras, sequence comparisons, and homology modeling suggest that the Dhr1-specific Ser-462-Ser-463 and Phe-469 play a key role in dhurrin hydrolysis. Similar data suggest that DIMBOAGlc hydrolysis determinants are not located within the extreme 47-amino acid-long C-terminal domain of Glu1.

Amino Acid Sequence↗
PubMed2000

Androgen receptor mutations in prostate cancer.

We analyzed the frequency and relevance of mutations in the coding region of the androgen receptor (AR) in genomic DNA extracted from 137 specimens of prostate cancer. The specimens were obtained from the primary tumors of patients affected by stage B disease [15 nonmicrodissected (group 1A) and 84 microdissected (group 1B)] and from the metastatic deposits of individuals with stage D1 disease [8 nonmicrodissected (group 2A) and 30 microdissected (group 2B)] who had not undergone androgen ablation therapy. The study was conducted by PCR-single strand conformational polymorphism (SSCP) analysis of exons 2-8 in the four groups and direct sequence analysis of exon 1 in group 1B. As positive and negative controls, we used genomic DNA extracted from genital skin fibroblasts of patients affected by various forms of androgen resistance with known mutations in the AR. To control for genetic instability, PCR-SSCP analysis of exon 2 of the human progesterone receptor was carried out on each specimen. The overall number of mutations detected was 11 (8%). No mutations were detected in any of the 99 patients with stage B disease. Eleven mutations were detected in exons 2-8 in 8 of the 38 patients with stage D1 disease (all in group 2B). Simultaneous analysis of exon 2 of the progesterone receptor was carried out, and no SSCP changes were identified. These data suggest that AR mutations are rare and presumably do not play a role in the initial phase of prostatic carcinogenesis. The presence of a significant number of AR mutations in metastatic disease indicates that mutations of this molecule may play a role in the most advanced phases of the natural history of this disease, either by facilitating growth or acquisition of the metastatic phenotype.

Humans↗
PubMed2000

A specific beta-glucosidase-aggregating factor is responsible for the beta-glucosidase null phenotype in maize.

Maize (Zea mays L.) beta-glucosidase was extracted from shoots of a wild-type (K55) and a "null" (H95) maize genotype. Enzyme activity assays and electrophoretic data showed that extracts from the null genotype had about 10% of the activity present in the normal genotype. Zymograms of the null genotype were devoid of any activity bands in the resolving gel, but had a smeared zone of activity in the stacking gel after native polyacrylamide gel electrophoresis. When extracts were made with buffers containing 0.5% to 2% sodium dodecyl sulfate, the smeared activity zone entered the resolving gel as a distinct band. These data indicated that the null genotypes have beta-glucosidase activity, but the enzyme occurs as insoluble or poorly soluble large quaternary complexes mediated by a beta-glucosidase-aggregating factor (BGAF). BGAF is a 35-kD protein and binds specifically to beta-glucosidase and renders it insoluble during extraction. BGAF also precipitates beta-glucosidase that is added exogenously to supernatant fluids of the null tissue extracts. The specific beta-glucosidase-aggregating activity of BGAF is unequivocally demonstrated. These data clearly show that the monogenic inheritance reported for the null alleles at the beta-glucosidase gene is actually for the BGAF protein, and BGAF is solely responsible for beta-glucosidase aggregation and insolubility and, thus, the apparent null phenotype.

Phenotype↗
PubMed1999

Expression of soluble and catalytically active plant (monocot) beta-glucosidases in E. coli.

Complementary DNAs encoding mature beta-glucosidase proteins Glu1 and Glu2 of maize were amplified by the polymerase chain reaction (PCR) and cloned into the expression vector pET21a. Both Glu1 and Glu2 isozymes were expressed in high yield ( approximately 3.8% of the total soluble protein and 32% of the total expressed protein) in E. coli. Recombinant enzymes were active on a variety of artificial and natural substrates at levels similar to those of their native counterparts isolated from maize seedlings. Western blot analysis confirmed that both recombinant isozymes were immunoreactive with maize anti-beta-glucosidase sera and their molecular sizes were identical to those of the native maize Glu1 and Glu2 isozymes. Zymogram assays in native gels revealed that recombinant enzymes had the same electrophoretic mobility and substrate specificity as their native counterparts.

Amino Acid Sequence↗
PubMed1999

Sexual behaviour during pregnancy.

The effects of pregnancy on sexuality were studied in 158 pregnant women. They were surveyed by questionnaire about sociodemographic variables and sexual behaviour. Dyspareunia was common in our study group during pregnancy. Pregnancy had a negative effect on orgasmic quality. Dyspareunia and orgasmic quality influenced coital frequency. Coital frequency declined as the month of the pregnancy increased. Pregnancy is a potent influence on sexuality irrespective of an individual's conditioning.

Adolescent↗
PubMed1998

Structure and expression of a dhurrinase (beta-glucosidase) from sorghum.

Sorghum (Sorghum bicolor L. Moench) has two isozymes of the cyanogenic beta-glucosidase dhurrinase: dhurrinase-1 (Dhr1) and dhurrinase-2 (Dhr2). A nearly full-length cDNA encoding dhurrinase was isolated from 4-d-old etiolated seedlings and sequenced. The cDNA has a 1695-nucleotide-long open reading frame, which codes for a 565-amino acid-long precursor and a 514-amino acid-long mature protein, respectively. Deduced amino acid sequence of the sorghum Dhr showed 70% identity with two maize (Zea mays) beta-glucosidase isozymes. Southern-blot data suggested that beta-glucosidase is encoded by a small multigene family in sorghum. Northern-blot data indicated that the mRNA corresponding to the cloned Dhr cDNA is present at high levels in the node and upper half of the mesocotyl in etiolated seedlings but at low levels in the root-only in the zone of elongation and the tip region. Light-grown seedling parts had lower levels of Dhr mRNA than those of etiolated seedlings. Immunoblot analysis performed using maize-anti-beta-glucosidase sera detected two distinct dhurrinases (57 and 62 kD) in sorghum. The distribution of Dhr activity in different plant parts supports the mRNA and immunoreactive protein data, suggesting that the cloned cDNA corresponds to the Dhr1 (57 kD) isozyme and that the dhr1 gene shows organ-specific expression.

Amino Acid Sequence↗
PubMed1998

Insertional polymorphism in introns 4 and 10 of the maize beta-glucosidase gene glu1.

The major beta-glucosidase isozyme Glu1 is encoded by a highly polymorphic gene (glu1) in maize. The glu1 gene comprises 12 exons and 11 introns. Two of these introns, introns 4 and 10, show insertional polymorphism: those in allele glu1-1 (represented by inbred line OH7B) are longer than those in other inbred genotypes and in two teosintes (Zea mexicana and Zea parviglumis) surveyed. Sequence data revealed that an increase in the length of intron 4 from 150 to 477 bp in OH7B is due to a short (11 bp) tandem duplication and a large insertion sequence of 313 bp plus a 4-bp (5' ATAG 3') direct repeat. The 313-bp insertion sequence (referred to as mzsTn-1) has all the features of a transposon, having a 25-bp well-conserved (3/25 mismatches) inverted repeat sequence at its termini flanked by a 4-bp direct repeat. The increase in length from 1041 to 1302 bp in intron 10 of OH7B is due to a 259-bp insertion sequence (referred to as mzsTn-2) plus a 2-bp (5' TA 3') direct repeat. The mzsTn-2 element also possesses all the hallmarks of a transposon: a 34-bp well-conserved (3/34 mismatches) inverted repeat sequence at its termini flanked by a 2-bp direct repeat. The mzsTn-1 element belongs to a new family of inverted repeat elements, while mzsTn-2 belongs to the Stowaway family of inverted repeat elements. Analysis of PCR products from amplifications off genomic-DNA templates, using primers derived from the inverted repeat termini, and Southern blotting data suggest that both small transposons are members of a multigene family. The occurrence of two different small transposons in introns of the same glu1 allele in inbred OH7B and their absence in other genotypes suggest that they have moved into this glu1 allele recently through mediation of their autonomous counterparts that are active in OH7B or in its ancestry.

Base Sequence↗
PubMed1996

Cisplatin and etoposide chemotherapy in the treatment of adult Wilms' tumor.

A 64-year-old man underwent left radical nephrectomy for stage III anaplastic Wilms' tumor. He received adjuvant chemotherapy consisting of cisplatin and etoposide. Complete clinical response was achieved and maintained for 12 months. A systemic relapse after 1 year also responded to three more cycles of cisplatin and etoposide. Although cisplatin- and etoposide-based chemotherapy was not used as a first-line therapy in adult patients with Wilms' tumor described in the literature, this case demonstrates the promising activity of this combination also in adults with this disease entity.

Chemotherapy, Adjuvant↗
PubMed1995

Effect of ejaculation on prostate-specific antigen levels in normal men.

While several manipulations such as digital rectal examination and cystoscopy have been shown to increase prostate-specific antigen (PSA) levels, lack of ejaculation for a period of time has been implicated as a cause of decreased serum PSA concentrations. However, the effect of ejaculation on the serum PSA concentration is not clear. This work determined the effect of ejaculation on serum PSA levels in normal men. Blood samples of 19 healthy subjects were taken before and 5 consecutive days after ejaculation. One subject was withdrawn from the study because of ejaculation during sleep, since another ejaculation was prohibited during the study. The mean PSA levels of the men before and 5 consecutive days after ejaculation were 0.79, 0.72, 0.63, 1.01, 0.71, and 0.74 ng/ml--not statistically significantly different. We conclude that ejaculation does not seem to affect the serum PSA concentration.

Adult↗