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T Ebner

Publications and source records attributed to T Ebner.

At least 37 records · Page 2Linked to original sources
PubMed2001

A prospective study on oocyte survival rate after ICSI: influence of injection technique and morphological features.

PURPOSE: To determine the influence of technical pitfalls and oocyte morphology on survival rate and cleavage behavior after ICSI. METHODS: A total of 2210 injection procedures was examined for morphological and technical deviations. Survival rate and cleavage behavior were evaluated. RESULTS: In 77.8% of all cases ICSI was unsuspicous. Out of 491 deviations from optimal injection deep penetration of the oocyte and abundant presence of cumulus cells showed significant correlation with degeneration rate (p < 0.001). Morphological anomalies associated with the periphery of the oocyte were rather related to degeneration than cytoplasmic anomalies (p < 0.001). Early embryonic development was not impaired by technical or morphological parameters. CONCLUSIONS: To conclude, these prospective data may be of prognostic value in regard of the number of embryos available for transfer and may help to improve treatment outcome.

Adult↗
PubMed2001

Acute puerperal inversion of the uterus--treatment by a new abdominal uterus preserving approach.

OBJECTIVE: Inversion of the uterus is still a rare (1, 2) but serious and life-threatening obstetric complication. It is said to be complete when the fundus uteri protrudes through the cervix and into the vagina. Within minutes a state of shock is reached due to pulling forces on the peritoneum as well as blood loss. METHODS: The vagina was entered by a longitudinal incision (3 m) below the contraction ring. Through this opening it was possible to advance two fingers (second and third finger of the left hand) into the vagina above the invaginated corpus uteri. The invaginated cavum uteri was loaded on these two fingers and, exerting counterpressure with the right hand, the inside was turned out. CONCLUSION: The present operative method guarantees easy reposition of the uterus in cases of failed vaginal manual repositioning. Furthermore, the cavum uteri remains intact and hysterectomy can be avoided.

Adult↗
PubMed2001

Laser assisted immobilization of spermatozoa prior to intracytoplasmic sperm injection in humans.

BACKGROUND: The conventional method of immobilization of spermatozoa prior to intracytoplasmic sperm injection (ICSI) is mechanical breakage of the tail by pressing it against the bottom of the injection dish. METHODS: This prospective self-controlled study was set up to evaluate the potential of a non-contact 1.48 microm wavelength diode laser in terms of immobilization. In addition, the fertilization rate and further development potential of such zygotes were investigated. The patients included in our study (n = 60) had oestradiol concentrations >2000 pg/ml, and thus a relatively high number of MII oocytes could be expected. Approximately half the oocytes were injected with laser treated spermatozoa (n = 262, study group) and the other half with mechanically immobilized spermatozoa (n = 252, control group). RESULTS: No significant differences between the two groups in terms of fertilization rate, early cleavage or blastocyst formation were observed. However, time required for identification, aspiration and injection of a potential spermatozoa was significantly shorter in the laser immobilized sperm group (P < 0.001). CONCLUSIONS: The application of a non-contact diode laser for sperm immobilization prior to ICSI is a potentially useful alternative to the conventional mechanical approach.

Adult↗
PubMed2000

Role of three-dimensional ultrasonographic measurement of endometrium volume as a predictor of pregnancy outcome in an IVF-ET program: a preliminary study.

OBJECTIVE: To evaluate the role of three-dimensional (3D) ultrasonographic measurement of the endometrium in predicting pregnancy in an IVF-ET program. DESIGN: Prospective study. SETTING: Center for assisted reproductive techniques. PATIENT(S): 65 women undergoing controlled ovarian hyperstimulation for IVF. INTERVENTION(S): Ultrasonographic examination on the day of hCG administration. MAIN OUTCOME MEASURE(S): Endometrial volume, endometrial thickness, and pregnancy rate. RESULT(S): The mean (+/-SD) endometrium volume (4.16 +/- 1.97 mL), endometrium thickness (11 +/- 2 mm), and estradiol level (1686.82 +/- 1057.10 pg/mL) in 21 pregnant women on the day of hCG administration did not differ statistically differ from the respective values in 44 nonpregnant women (4.53 +/- 1.79 mL; 11 +/- 2 mm, 1883.56 +/- 1147.21 pg/mL). Receiver-operating characteristic curves showed that the area under curve (AUC) was 0.57 for endometrial volume and 0.48 for endometrial thickness. Using a cut-off value of 2.5 mL for endometrial volume to predict pregnancy, results of the Fisher exact test were statistically significant. No significant cut-off value was found for endometrial thickness. CONCLUSION(S): Endometrial volume and thickness on the day of hCG administration did not predict occurrence of pregnancy. A minimum volume of 2.5 mL appeared to favor pregnancy. The predictive value of 3D ultrasonographic measurement of endometrial volume and thickness was better than that of 2D measurement.

Austria↗
PubMed2000

Prognostic value of first polar body morphology on fertilization rate and embryo quality in intracytoplasmic sperm injection.

The association between oocyte morphology and subsequent fertilization rate and embryo quality in intracytoplasmic sperm injection (ICSI) is subject to considerable controversy. This retrospective study was carried out to investigate a possible prognostic value of first polar body morphology with regard to fertilization rate and embryo quality. A total of 70 consecutive ICSI cases was included in this study. The results showed that classification based on first polar body morphology revealed a significant correlation with fertilization rate (P < 0.025) and embryo quality (P < 0.001). Cytoplasmic criteria showed no correlation in this respect. Present data indicate that ICSI of oocytes with intact well-shaped first polar bodies yields higher fertilization rates and higher quality embryos.

Adult↗
PubMed2000

Three-dimensional endometrial volume estimation as a predictor of pituitary down-regulation in an IVF-embryo transfer programme.

To examine the role of three-dimensional (3D) volume estimation in predicting pituitary down-regulation in an IVF-embryo transfer programme, 46 women were treated with buserelin acetate for down-regulation prior to and concomitantly with ovarian stimulation. Receiver operating characteristic (ROC) curve analysis was used for statistics. The area under the curve (AUC) provides a measure to show how good (AUC close to 1) or how poor (AUC close to 0.5) a test is. If down-regulation was defined as oestradiol <40, <60 or <80 pg/ml, the AUC of 3D-ultrasound was 0.57, 0.83 and 0.97 respectively. The highest sensitivity (100%) and specificity (93.2%) of 3D-ultrasound was achieved if down-regulation was defined as oestradiol <80 pg/ml (n = 44), with an endometrial volume of 1.9 ml. If down-regulation was defined as oestradiol <60 pg/ml (n = 42) the best combination of highest sensitivity (95.2%) and specificity (75. 0%) was obtained with an endometrial volume of 1.9 ml. The comparison of 3D volume calculation with endometrial thickness measurement revealed no significant difference in predicting down-regulation. 3D volume estimation provides a new tool for diagnosing relative hypo-oestrogenism or down-regulation, but it was not superior to two-dimensional ultrasound.

Adult↗
PubMed1999

Highly sensitive gas chromatographic-tandem mass spectrometric method for the determination of morphine and codeine in serum and urine in the femtomolar range.

A sensitive and specific method was developed for the determination of codeine and morphine in human serum and for the determination of trace amounts of endogenous morphine in human urine. The analytes were recovered from serum by a simple liquid-liquid extraction method. Urine samples were hydrolyzed, and purified by two liquid-liquid extraction steps and a solid-phase extraction. Samples were derivatized to the pentafluoropropionic esters and measured by gas chromatography tandem mass spectrometry. Using the deuterated analogues as internal standards a limit of quantification of 20 fmol/ml (5.7 pg/ml) morphine and 500 fmol/ml (150 pg/ml) codeine in human serum and of 2.5 fmol/ml (0.71 pg/ml) morphine in urine was achieved. The method was suitable for the determination of morphine and codeine in pharmacokinetic studies and for the determination of the urinary excretion of endogenous morphine.

Calibration↗
PubMed1999

Elective transfer of embryos selected on the basis of first polar body morphology is associated with increased rates of implantation and pregnancy.

OBJECTIVE: To determine the relationship between first polar body morphology and implantation rate and pregnancy rate (PR), to facilitate decision making concerning elective ET. DESIGN: Prospective, randomized study. SETTING: Fertility center. PATIENT(S): One hundred fifty-eight consecutive patients (173 intracytoplasmic sperm injection cycles) resulting in embryo transfers. INTERVENTION(S): In our study group, priority in ET was given to embryos derived from well-shaped first polar bodies, whereas selection of embryos for transfer in the control group was based exclusively on the degree of embryo fragmentation. MAIN OUTCOME MEASURE(S): Total numbers of implantations and pregnancies, PR and implantation rate, and rates of multiple pregnancy and miscarriage. RESULT(S): In the study cohort, 212 embryos were transferred. In the control group, 313 embryos were transferred. The implantation rate and PR were significantly lower in the control group than in the study cohort. In addition, the rate of multiple pregnancy was significantly higher in the study group. CONCLUSION(S): Elective transfer of embryos selected on the basis of first polar body morphology results in higher implantation and pregnancy rates. Multiple pregnancy can be avoided by transferring a reduced number of embryos selected on the basis of first polar body morphology.

Adult↗
PubMed1999

Reproducibility of transvaginal three-dimensional endometrial volume measurements during ovarian stimulation.

Before estimating the clinical role of a method, the reproducibility has to be evaluated precisely. This study aimed to document the reproducibility of the endometrial volume measurement by three-dimensional (3D)-ultrasound. The volume measurements were done on 57 consecutive in-vitro fertilization (IVF) patients with either the full planar (contour) or the three distance method. A paired t-test provided no statistically significant difference between the two methods. Linear regression analysis, using the full planar method as independent and the other as dependent variables, yielded the following results: intercept = 0.348, not statistically different from 0; slope = 0.962, statistically different from 1 (P < 0.01). Interobserver reliability for the three distance method was 0.6667 and for the full planar method was 0.9565. Intra-observer reliability for the three distance method was 0.8426 and for the full planar method 0.9394. The correspondence between and within observers seemed to be good. Both methods are reliable, but the full planar method seems to provide slightly better reproducibility in regard to endometrium volume measurement.

Adult↗
PubMed1999

Activation of human cytochrome P-450 3A4-catalyzed meloxicam 5'-methylhydroxylation by quinidine and hydroquinidine in vitro.

In humans, meloxicam is metabolized mainly by cytochrome P-450 (CYP)-dependent hydroxylation of the 5'-methyl group. The predominant P-450 enzyme involved in meloxicam metabolism is CYP 2C9, with a minor contribution of CYP 3A4. Quinidine, a CYP 3A4 substrate commonly used as a selective in vitro inhibitor of CYP 2D6, was found to markedly increase the rate of meloxicam hydroxylation during in vitro experiments with human liver microsomes. A similar activation was observed with other compounds that are structurally related to quinidine. Besides quinidine, quinine and hydroquinidine were the most potent activators of meloxicam hydroxylation. Using expressed cytochrome P-450 enzymes and selective chemical inhibitors of CYP 2C9 and CYP 3A4, it was found that quinidine markedly increased the rate of CYP 3A4-mediated meloxicam hydroxylation but was virtually without effect on CYP 2C9. Kinetic analysis was performed to obtain insight into the possible mechanism of activation of CYP 3A4 and into the mutual interaction of quinidine/hydroquinidine and meloxicam. Quinidine and hydroquinidine decreased Km and increased Vmax of meloxicam hydroxylation, which was consistent with a mixed-type nonessential activation. Meloxicam, in turn, decreased both Km and Vmax of quinidine metabolism by CYP 3A4, indicating an uncompetitive inhibition mechanism. These results support the assumption that CYP 3A4 possesses at least two different substrate-binding sites. A clinically relevant effect on meloxicam drug therapy is not expected, because the most likely outcome in practice is moderately decreased meloxicam plasma concentrations.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1999

Disposition and chemical stability of telmisartan 1-O-acylglucuronide.

Telmisartan 1-O-acylglucuronide, the principal metabolite of telmisartan in humans, was characterized in terms of chemical stability and the structure of its isomerization products was elucidated. In addition, pharmacokinetics of telmisartan 1-O-acylglucuronide were assessed in rats after i.v. dosing. Similar to other acylglucuronides, telmisartan 1-O-acylglucuronide and diclofenac 1-O-acylglucuronide, which was used for comparison, showed the formation of different isomeric acylglucuronides on incubation in aqueous buffer. The isomeric acylglucuronides of telmisartan consisted of the 2-O-, 3-O-, and 4-O-acylglucuronides (alpha,beta-anomers). First order degradation half-lives of 26 and 0. 5 h were observed on incubation in buffer of pH 7.4 for the 1-O-acylglucuronides of telmisartan and diclofenac, respectively. This indicated that the 1-O-acylglucuronide of telmisartan was among the most stable acylglucuronides reported to date. The high stability of telmisartan 1-O-acylglucuronide was confirmed by in vitro experiments that indicated only very low covalent binding of telmisartan acylglucuronide to human serum albumin but a considerable amount of covalently bound radioactivity with the acylglucuronide of diclofenac. After i.v. dosing to rats, telmisartan 1-O-acylglucuronide was rapidly cleared from plasma with a clearance of 180 ml/min/kg, compared with 15.6 ml/min/kg for the parent compound. Because telmisartan 1-O-acylglucuronide exhibited a comparably high chemical stability together with a high clearance that resulted in low systemic exposure, the amount of covalent binding to proteins should be negligible compared with other frequently used drugs, such as furosemide, ibuprofen, or salicylic acid.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

Assessment of microsomal tolbutamide hydroxylation by a simple thin-layer chromatography radioactivity assay.

A radio thin-layer chromatographic method is described for in vitro measurement of tolbutamide methylhydroxylation as an alternative to the commonly used HPLC assay. After the incubation experiments of [14C]tolbutamide with human liver microsomes, the supernatants were directly spotted onto standard silica gel TLC plates and developed in a horizontal chamber using a solvent system consisting of toluene-acetone-formic acid (60:39:1, v/v). Dried TLC plates were exposed to a phosphor imager plate and quantificated by use of a phosphor imager. Reaction rates were calculated from the ratio of labelled metabolite to the total radioactivity. The correlation coefficient between HPLC and the TLC method was 0.978 (n=14). The described method provides a valuable tool for the determination of tolbutamide hydroxylation activity in human liver microsomes.

Chromatography, High Pressure Liquid↗
PubMed1995

Mechanism of cytochrome P450 2D6-catalyzed sparteine metabolism in humans.

Two different reaction mechanisms for the formation of the two human enamine-structured sparteine metabolites by cytochrome P450 2D6 have been discussed in the literature. These mechanisms are either initial one-electron oxidation of N1 of sparteine followed by deprotonation of the aminium radical cation, resulting in the formation of different carbon radicals and oxygen rebound of the carbon radicals, or oxidation of the carbon atoms adjacent to N1 by the enzyme, directly producing the respective carbon radicals. With a spectrum of deuterium-labeled isotopomers of sparteine, stereoselectivity and kinetic isotope effects of human sparteine metabolism were investigated by in vitro and in vivo experiments and were compared with chemical oxidation of 17-oxosparteine. These experiments revealed that the major human sparteine metabolite 2,3-didehydrosparteine is formed via highly stereoselective abstraction of the 2 beta-hydrogen atom; the deuterium label was completely retained during metabolism when 2R-[2H]sparteine was used as substrate. Chemical oxidation of 17-oxosparteine by Ce4+, as a model for one-electron oxidation of N1 of a sparteine-like structure, resulted in the sole formation of the 5,6-unsaturated enamine, and no 2,3-unsaturated enamine, structurally equivalent to the human major metabolite, was found. An unequivocal discrimination between the two possible reaction mechanisms was not possible by simple interpretation of the magnitude of the kinetic deuterium isotope effects. However, results of competitive and noncompetitive experiments revealed the presence of a nondissociative enzymatic mechanism for the formation of the two sparteine metabolites, i.e., the sparteine molecule that is bound to the substrate binding site of cytochrome P450 2D6 performs orientational changes without dissociating from the activated enzyme/substrate complex before the product-determining first irreversible reaction step. These results agree with the hypothesis that sparteine metabolism proceeds by direct carbon oxidation. Because electron transfer from amines to P450 may occur over some distance, the possibility of a sequential electron-proton transfer reaction during sparteine metabolism cannot be ruled out completely as an alternative reaction mechanism for sparteine metabolism.

Binding, Competitive↗
PubMed1994

Use of cloned and expressed human liver UDP-glucuronosyltransferases for analysis of drug glucuronide formation and assessment of drug toxicity.

Five cloned human hepatic UDP-glucuronosyltransferase (UGT) cDNAs were stably expressed in tissue culture cell lines. More than 100 drugs and xenobiotics were used as substrates for glucuronidation catalyzed by the cloned human transferases to determine the chemical structures accepted as substrates. UGT-HP1 exhibited a limited substrate specificity for planar phenolic compounds, whereas UGT-HP4 was more accepting of nonplanar phenols, anthraquinones, flavones, alphatic alcohols, aromatic carboxylic acids, steroids and many drugs of varied structure. UGT-HP3 (bilirubin UGT) catalyzed the glucuronidation of ethinylestradiol. UGT-H6 and UGT-H25 (steroid/bile acid UGTs) also catalyzed the glucuronidation of some xenobiotics. Levels of UGT-HP4 activity towards some substrates were sufficient to allow determination of kinetic parameters for the enzyme reaction. Further, metabolism of drugs could be studied by addition to the recombinant cell lines in culture and extraction of the media allowed analysis of glucuronide formation. The protection afforded against cytotoxic drugs was observed. The data presented here demonstrate the potential of using these recombinant cell lines for investigation of phase II metabolism by human UGTs and subtle differences in protein structure which affect their specificity.

Cell Line↗