Biomedical subjects

K Sterzik

Publications and source records attributed to K Sterzik.

At least 55 records · Page 3Linked to original sources

PubMed1994

[Do preparation techniques induce ultrastructural sperm damage? An electron microscopic study].

We investigated the possibility of ultrastructural damage to human spermatozoa induced by different sperm preparation techniques. Ejaculates from 20 normozoospermic men were divided into equal aliquots and processed by glass wool filtration, Percoll density gradient centrifugation, and a simple two-step centrifugation procedure which served as a control. Ultrastructural damage was assessed by scanning electron microscopy. Compared with Percoll density gradient centrifugation, glass wool filtration yielded a significantly increased proportion of intact acrosomes (p < 0.05). However, both preparations gave significantly better results than control (p < 0.001 and p < 0.01 for glass wool filtration and Percoll centrifugation, respectively). The significance of the conspicuous bending of sperm tails after Percoll centrifugation is not yet known. In conclusion, both glass wool filtration and Percoll centrifugation are efficient techniques for the accumulation of spermatozoa with intact acrosomes. Because of the higher sperm recovery rate, glass wool filtration appears to be the more appropriate method.

Acrosome↗

PubMed1994

[Initial pregnancies after intravaginal transport and partial zona dissection of human ova].

We report on 72 couples with previous failure of fertilisation during several trials of conventional in-vitro fertilisation (IVF). In the present study part of the aspirated oocytes was subjected to partial zona dissection (PZD) before insemination, thereby achieving 7 pregnancies during 104 cycles. Normal in-vitro insemination of the remaining zona-intact oocytes was again unsuccessful. Since microinsemination techniques, in contrast to conventional IVF, are not yet being offered by many clinics, we developed the following new concept: hormonal stimulation, sonographic control of follicular growth, aspiration of oocytes, and sperm preparation were performed at the usual place (Munich) whereas PZD and control IVF were accomplished in another laboratory (Ulm). In order to transport the gametes between these two institutes, we modified the previously reported intravaginal culture (IVC) of inseminated oocytes by transferring oocytes and spermatozoa into separate plastic capsules. In our view, this procedure offers a suitable opportunity for infertile couples living too far away from a microinsemination centre to afford long daily journeys or even several overnight stays for superovulation treatment. The fertilisation and pregnancy rates in our study are comparable to those reported in the literature.

Adult↗

PubMed1994

[Effect of different follicle puncture methods on hormone homeostasis in the woman. Studies within the scope of an in vitro fertilization-embryo transfer program].

Different methods for follicular puncture which were used in an in vitro fertilization-embryo transfer program have been analyzed in order to determine their influence on plasma levels of estradiol, progesterone, prolactin and beta-endorphins. Thirty-eight patients awaiting oocyte aspiration were randomized into a laparoscopic (n = 20) and an ultrasound-guided oocyte aspiration group (n = 18). No differences were observed as far as estradiol and progesterone levels and embryo transfer rates were concerned. When using the laparoscopic technique, prolactin levels were found to be elevated 1.5 times in comparison with the ultrasound-guided aspiration procedure, which is highly significant (p < 0.001). Also, beta-endorphins peaked at a significantly higher level during laparoscopy (27.8 vs. 20.7 mol/l, p < 0.001). The enhanced prolactin and beta-endorphin levels reflect an increased stress response during laparoscopy. With respect to less trauma and shorter duration of the procedure, we now perform the sonographically guided transvaginal aspiration technique in our program almost exclusively.

Adult↗

PubMed1994

Cytogenetics of human spermatozoa. The frequency of various chromosome aberrations and their relationship to clinical and biological parameters.

Human sperm chromosomes can be visualized after their fusion with zona-free hamster eggs. We analyzed a total of 867 metaphases from 33 men that had been classified into three different groups. We present a detailed summary of the kind and frequency of chromosome aberrations we encountered. A comparison of our results with previous studies demonstrates considerable variations in numerical and structural chromosome anomalies in spermatozoa from normal, healthy men. The possible reasons for this are discussed. We reviewed some factors which are supposed to correlate with the occurrence of sperm chromosome aberrations; the effect of paternal age is still uncertain.

Adult↗

PubMed1993

Chromosomal analysis of unfertilized human oocytes prepared by a gradual fixation-air drying method.

Two hundred and sixty-five unfertilized human metaphase II (M II) oocytes from an in vitro fertilization program were studied cytogenetically using our chromosomal technique, a gradual fixation-air drying method. Of the 265 oocytes, 185 (70%) were successfully karyotyped. There were 21 aneuploids (11.4%) consisting of 8 hyperhaploids (4.3%), 11 hypohaploids (5.9%) and 2 complex cases (1.1%). There were also 9 structural anomalies (4.9%) and 18 diploids (9.7%). In aneuploidy, the loss or gain of dyads (so-called nondisjunction) occurred more frequently than the loss or gain of monads (so-called predivision). The frequency of abnormally behaved chromosomes (segregation errors) due to nondisjunction, anaphase lag and predivision was studied among the seven chromosomal groups (A-G) and compared with the frequency expected from an equal probability of segregation errors in each of the 23 chromosomes. The observed frequency was somewhat higher than the expected frequency in groups E and G but the difference was not statistically significant in either group. These results were discussed in relation to previous studies on human M II oocyte chromosomes.

Adult↗

PubMed1993

Scanning electron microscopy of human sperms after preparation of semen for in-vitro fertilization.

Ultrastructural changes of human sperms after routine preparation for in-vitro fertilization were examined by scanning electron microscopy. Studies were performed with freshly ejaculated semen of 21 normozoospermic patients. Spermatozoa were analysed at 10000-fold (sperm head with acrosome, postacrosomal border and postnuclear cap) and 2500-fold (midpiece and endpiece of sperm tail) magnification. Compared with untreated specimens, slight membrane damage was found after routine washing and centrifugation procedures in swim-up preparations. However, on the basis of a score system for quantification of morphologic data, no statistically significant differences existed between untreated semen and swim-up preparations. We conclude that, with normozoospermic semen, the rate of ultrastructural damage attributable to sperm-washing procedures is too low to be of clinical consequence.

Acrosome↗

PubMed1993

Tamoxifen treatment of oligozoospermia: a re-evaluation of its effects including additional sperm function tests.

Because of previous contradictory results, we reevaluated the effects of tamoxifen on 29 men presenting with idiopathic oligozoospermia. To determine whether a possible increase in sperm concentration might be correlated with an improvement of sperm quality, the hamster ovum penetration (HOP) test and the hypo-osmotic swelling (HOS) test were included as additional tests of sperm function. Patients were treated with tamoxifen (20 mg/day) for 3 months. From 4 weeks until the end of the study, tamoxifen had a significant effect (P < 0.001) on blood levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), and estradiol (E2). Prolactin (PRL) concentrations were not altered significantly (P > 0.05). There was no significant improvement (P > 0.05) of conventional semen parameters (volume, concentration, motility, morphology), and of HOP and HOS test results. The lack of correlation between a rise in hormone levels and improvement of sperm quality suggests that tamoxifen is of questionable value in men with idiopathic oligozoospermia.

Adult↗

PubMed1993

First pregnancies after intravaginal transport and partial zona dissection of human oocytes.

We report on 72 couples with previous failure of fertilization during several trials of conventional IVF. For the present study, a part of the aspirated oocytes was subjected to partial zona dissection before insemination, thereby achieving 7 pregnancies during 104 cycles. Normal in vitro insemination of the remaining zona-intact oocytes was unsuccessful again. Because microinsemination techniques, in contrast to routine IVF, are not yet offered by many clinics, we developed the following new concept: hormonal stimulation, sonographic control of follicular growth, aspiration of oocytes, and sperm preparation were performed at the usual place (Munich), whereas partial zona dissection and control IVF were accomplished in another laboratory (Ulm). To transport the gametes between these two institutes, we modified the previously reported intravaginal culture of inseminated oocytes by transferring oocytes and spermatozoa into separate plastic capsules. In our view, this procedure offers an opportunity for infertile couples living too far away from a microinsemination center to afford long daily journeys or even several overnight stays just for superovulation treatment. The fertilization and PRs in our study are comparable with those reported in the literature.

Capsules↗

PubMed1993

[Discordant growth in twin pregnancy--value of Doppler ultrasound].

A 4 MHz continuous-wave Doppler device was used to study uterine and umbilical arterial wave forms in 91 pairs of twins between 18th and 40th week of gestation. Biometry and cord localisation were effected by real-time ultrasound. The results of 182 Doppler flow examinations showed that umbilical flow velocimetry may prove relevant for early identification of twin pregnancies with discordant growth. Depending on the interval between examination and delivery, sensitivity and specificity values between 44% and 66%, and 66% and 73%, respectively, were obtained. A high resistance index in umbilical arteries was indicative of intrauterine growth retardation, at a specificity of 69% and a sensitivity of 44%. For uteroplacental as well as foetoplacental flow velocity waveform assessment, singleton reference values may be used, whereas, by reason of its low sensitivity, Doppler flow velocimetry does not lend itself as a primary diagnostic tool for intrauterine growth retardation. It can signal pathologic blood flow profiles, which are often associated with added risks, such as pregnancy-induced hypertension, foetal acidosis and stillbirth and can contribute to early detection of twin pregnancies that require close clinical and cardiotocographic surveillance.

Blood Flow Velocity↗

PubMed1993

[Cytogenetics of unfertilized or uncleaved oocytes within the scope of in vitro fertilization: correlation with maternal age].

A cytogenetic analysis could be performed on 343 out of 566 oocytes, which remained unfertilized or uncleaved during our IVF programme. The results were analysed with relation to the women's age by classifying the patients into two age groups (< or = 35 years and > 35 years). There was no significant difference for the corresponding total rates of abnormal oocytes (27.7% vs. 42.4%), the rates of aneuploidy (14.5% vs. 18.2%), and the rates of hyperhaploidy (4.8% vs. 3.0%). These results do not support the assumption of an increase in (numerically) abnormal gametes with increasing maternal age, which is of special interest in cases of trisomy 21. However, it is not possible to draw any definite conclusions, because of the low number of gametes, which were analysed in the upper age group.

Adult↗

PubMed1993

Polynomial analysis of placental flow patterns in growth-retarded fetuses.

Correct interpretation of conspicuous blood flow velocity waveforms cannot rely solely on the evaluation of uteroplacental vascular Doppler flow patterns by means of angle-independent indices such as the resistance or pulsatility index. In addition to the degree of pulsatility, the waveform shape between the systolic and diastolic peak values is of considerable consequence. A subdivision of the total flow waveform into orthogonal polynomial components allows both pulsatility evaluation and notching to be registered, providing a higher sensitivity in identification of pathological vascular resistance. Accurate recording and assessment of the flow waveform is therefore an important qualitative criterion for the classification of Doppler flow patterns in pregnancies with reduced uteroplacental perfusion.

Blood Flow Velocity↗

PubMed1993

Concerted action of human chorionic gonadotropin and norepinephrine on intracellular-free calcium in human granulosa-lutein cells: evidence for the presence of a functional alpha-adrenergic receptor.

Luteal cells are known to possess receptors for LH/hCG and receptors of the beta-adrenergic type. Interactions of specific agonists with either receptor lead to the activation of adenylate cyclase and subsequently to an increase of cAMP. Since in the human there is also evidence for the presence of alpha-adrenergic receptors, we have investigated whether activation of these receptors is linked to calcium as a second messenger and performed measurement of intracellular free calcium (Ca2+) with Fura-2 in single human granulosa-lutein cells. Addition of either hCG (100, 1,000, 25,000 IU/L) or norepinephrine (NE; known to interact with both alpha- and beta-adrenergic receptors), beta-adrenergic receptor agonist isoproterenol (ISO), or alpha-adrenergic receptor agonist phenylephrine (PHE; all at 10 and 100 mumol/L) did not increase free intracellular Ca2+. However, the addition of combinations of NE/hCG, PHE/hCG, but not the combination ISO/hCG, induced a transient increase in cytosolic free Ca2+. The NE/hCG-evoked calcium signal was not abolished in the presence of the beta-adrenergic receptor antagonist propranolol and was not affected by removal of extracellular Ca2+. Furthermore, we tested whether catecholamines affected the release of progesterone in the presence or absence of hCG. As expected, hCG (10,000 IU/L) stimulated progesterone release by cultured granulosa-lutein cells. When these cells were incubated with NE, PHE, or ISO (at 10 mumol/L), production of progesterone by these cells was not affected. However, the combinations of NE and PHE with hCG abolished the hCG-induced progesterone accumulation, but ISO coincubated with hCG did not. Taken together, our results indicate: 1) the presence of functional alpha-adrenergic receptors on human granulosa-lutein cells; 2) simultaneous activation of two different receptors (for hCG and alpha-agonists) are able to evoke intracellular Ca2+ elevation, implicating postreceptor interactions in human granulosa lutein cells; 3) this process occurs even in the absence of extracellular Ca2+, indicating the involvement of intracellular Ca2+ stores, most likely due to activation of phosphoinositide pathway; 4) catecholamines most likely acting via alpha-adrenergic receptors, inhibit the LH/hCG-induced release of progesterone.

Calcium↗

PubMed1993

Effect of oxytocin on free intracellular Ca2+ levels and progesterone release by human granulosa-lutein cells.

Oxytocin and its receptor are found in the corpus luteum in a variety of species, including the human. In the present study we used fura-2 microfluorimetry to investigate whether activation of the oxytocin receptor of cultured human granulosa-lutein cells causes intracellular calcium (Ca2+) signals and affects progesterone release. Although after 1 day in culture, cells were not responsive to oxytocin, the number of responsive cells increased steadily during the first 3 days in culture, reaching a maximum on days 4 and 5 (59-66%) and then declined again until day 8. Effective oxytocin concentrations were apparently independent of the culture day, and concentrations as low as 10 nmol/L increased intracellular free Ca2+ levels from 70-140 nmol/L (basal levels) to maximal peak levels of 800 nmol/L. The oxytocin-induced Ca2+ signal was not affected by removal of extracellular Ca2+ with EGTA. Moreover, depletion of intracellular Ca2+ stores by ionomycin treatment rendered the cells unresponsive to oxytocin, pointing also at the intracellular source of the oxytocin-inducible Ca2+ signal. Interestingly, after one single stimulation with oxytocin, cells became refractory to additional stimuli, and only extremely high concentrations of oxytocin induced a second increase in intracellular free Ca2+. To examine the possible effects of oxytocin on progesterone release by cultured cells, we incubated cells on culture day 2 (20% responsive cells in the fura measurements) and culture day 5 (66% responsive cells in the fura measurements) for 24 h with oxytocin (10 nmol/L) and hCG (10,000 IU/L). Although hCG significantly stimulated progesterone release, oxytocin alone was without a stimulatory effect on either day. However, a significant augmentation of the effect of hCG on progesterone release was found in incubations of cells on day 5. Interestingly, the effects of hCG also included stimulation of oxytocin release by cultured granulosa-lutein cells into the culture medium, as determined by RIA. In summary, our data indicate the presence of a functional oxytocin receptor on human granulosa-lutein cells that is linked to Ca2+ as a second messenger released from intracellular Ca2+ stores. The number of oxytocin-responsive cells increases during differentiation in culture. Moreover, oxytocin release induced by hCG and a stimulatory effect of oxytocin on the hCG-induced progesterone production during the period of maximal responsiveness of cultured cells were found. We, therefore, propose that oxytocin may have autocrine and/or paracrine functions in human granulosa-lutein cells, including fine-tuning of progesterone release.

Calcium↗

PubMed1993

[Correlation between cytogenetic anomalies of human spermatozoa and sperm morphology as well as age of patients studied].

Sperm chromosomes from 15 fertile men were analyzed after fusion of their spermatozoa with zona-free hamster eggs. The total proportion of abnormal metaphases as well as the proportions of aneuploidy and structural aberrations were calculated for every man and examined for linear correlations with sperm morphology and the age of the persons studied. A positive correlation between the cytogenetic parameters and the percentage of abnormal sperm morphology was not evident, suggesting that assessment of sperm morphology cannot be used as an indicator of chromosomal damage in human spermatozoa. In contrast, there was a more distinct positive correlation between the age of donors and the three cytogenetic parameters studied. Analogous calculations for two other study groups (group S: male subfertility; group HA: habitual abortions of the wives with unknown etiology) provided less clear results that may be attributed to the lower number of patients or to the existence of special indications as mentioned above.

Abortion, Habitual↗

PubMed1993

[Cytogenetics of unfertilized or undivided oocytes within the scope of in vitro fertilization: relation to the kind of hormonal stimulation].

A cytogenetic analysis could be performed on 343 out of 566 oocytes which remained unfertilized or uncleaved during our in vitro fertilization (IVF) programme. The results were analyzed in relation to the kind of ovarian stimulation by classification of the patients into two groups: treatment with human menopausal gonadotropin (hMG) or treatment with clomiphene citrate (CC). There was no significant difference for the total rates of abnormal oocytes (hMG: 28.6%, CC: 32.2%), the rates of aneuploidy (hMG: 14.4%, CC: 16.9%), and the rates of hyperhaploidy (hMG: 3.9%, CC: 8.5%). These results suggest that the kind of medication for induction of multiple follicular growth does not influence the rate of cytogenetic anomalies in human oocytes.

Chromosome Aberrations↗

PubMed1992

Numerical chromosome anomalies after fertilization of freeze-thawed mouse oocytes.

The chromosome complement of first cleavage stage mouse embryos was analyzed to investigate the effect of slow freezing-fast thawing cryopreservation on chromosome numbers by comparing these numbers with those found fresh after fertilization of control oocytes. Fewer frozen-thawed (34.1%) than control oocytes (75.0%) cleaved to the 2-cell stage after in vitro fertilization. The incidence of hyperploidy was significantly increased by freezing (4.5% vs. 0% in controls). Polyploidy was not significantly affected (17.0% for freeze-thaw embryos vs. 26.2% for controls).

Aneuploidy↗

PubMed1992

Is there any correlation between follicular fluid hormone concentrations, fertilizability, and cytogenetic analysis of human oocytes recovered for in vitro fertilization?

Constituents of FF have been suspected to influence fertilizability and cytogenetic constitution of human oocytes. We therefore analyzed the FF concentrations of E2, P, T, and PRL for 114 oocytes recovered for IVF. Forty-six of these oocytes were fertilized and transferred to the maternal uterus. Among the unfertilized gametes, 27 were not analyzable, 30 were normal haploid, and 11 were classified as abnormal. There was no significant difference between fertilized and unfertilized oocytes for FF concentrations of E2, P, T, and PRL and for the E2:P ratios. Similarly, we detected no significant difference between normal and abnormal oocytes for these parameters.

Body Fluids↗

PubMed1992

Cytogenetics of human spermatozoa: correlations with sperm morphology and age of fertile men.

Sperm chromosomes from 15 fertile men were analyzed after fusion of their spermatozoa with zona-free hamster eggs. The total proportion of abnormal metaphases as well as the proportions of aneuploidy and structural aberrations were calculated for every man and examined for linear correlations with [1] sperm morphology and [2] the age of the persons studied. A positive correlation between the cytogenetic parameters and the percentage of abnormal sperm morphology was not evident, suggesting that assessment of sperm morphology cannot be used as an indicator of chromosomal damage in human spermatozoa. In contrast, there was a more distinct positive correlation between the age of donors and the three cytogenetic parameters studied.

Adult↗