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Biomedical subjects

A Senn

Publications and source records attributed to A Senn.

At least 37 records · Page 2Linked to original sources
PubMed1995

Microdissection of mouse and human zona pellucida using a 1.48-microns diode laser beam: efficacy and safety of the procedure.

OBJECTIVE: To investigate the efficacy and safety of a small and affordable 1.48-microns continuous wave diode laser for zona pellucida (ZP) microdissection. DESIGN: Mouse and human oocytes and zygotes were submitted to ZP drilling. The hole characteristics and possible laser-induced structural alterations of the neighboring cytoplasm were investigated with scanning and transmission electron microscopy. The safety of the procedure was checked on control and drilled zygotes by determining their ability to develop in vitro and in vivo. SETTING: Collaborative study between three Swiss academic centers. INTERVENTIONS: The collimated diode laser beam was delivered through a 45x objective of an inverted microscope and focused through the culture dish and culture medium in 1- to 3-microns spots. MAIN OUTCOME MEASURE: Safety assessment of the laser drilling procedure. RESULTS: The 1.48-microns radiation achieves a rapid, precise, and easily controlled lysis of the ZP without any micromanipulative handling of the eggs. Different shapes of holes can be produced by varying the laser beam intersection site on the ZP, laser power, and irradiation time. The energy needed to drill holes of a given diameter is greater for zygotes than for oocytes. Safety of the drilling procedure is confirmed by the lack of damage at the ultrastructural and biologic levels. CONCLUSIONS: The low-cost 1.48-microns diode laser allows an easy, objective-driven, nontouch microdissection of the ZP. The procedure is safe, as drilled embryos give rise to normal and fertile offspring.

Animals↗
PubMed1995

Timing of hCG administration in cycles stimulated for in vitro fertilization: specific impact of heterogeneous follicle sizes and steroid concentrations in plasma and follicle fluid on decision procedures.

The timing of ovulation induction is usually decided according to estradiol plasma concentrations and follicle size. We administered human chorionic gonadotropin (hCG) when at least three follicles of 16 mm or more in diameter and adequate estradiol plasma concentrations were detected. We studied the percentage of mature oocyte-cumulus-corona radiata complexes, estradiol and progesterone concentrations in a heterogeneous sized follicle population (range 10-20 mm, n = 90) to perform a retrospective analysis of the adequacy of criteria adopted for the timing of ovulation induction. Plasma and follicular fluid were obtained from 20 normo-ovulating women (aged 28-37 years) treated with gonadotropin releasing hormone analogs (GnRH-a) and human menopausal gonadotropin (hMG) for in vitro fertilization (IVF). No correlation was found between the mean individual follicular fluid estradiol concentration (500-5640 nmol/l) and the respective maximum concentration in plasma (2-16 nmol/l). The estradiol concentration was similar in all follicles. Total follicular fluid estradiol concentration was found to be correlated with follicular fluid volume (r = 0.771, p < 0.01). On the day of hCG administration, the concentration of estradiol in the plasma but not the follicular fluid was correlated with the number of oocyte-cumulus-corona radiata complexes collected (p < 0.01) and the number of mature complexes (p < 0.01). At oocyte pick-up, the plasma concentration of progesterone was correlated (p < 0.01) with number of complexes collected and the number of mature complexes. The percentage of mature complexes collected (77.5%) was higher than suggested by the number of leading follicles. This indicates that our criteria for administering hCG were adequate and that heterogeneous follicle size does not exclude a high rate of mature oocyte-cumulus-corona radiata complexes.

Adult↗
PubMed1994

[Visit to Oxford].

Explore the source record for details and available documents.

Education, Nursing↗
PubMed1993

[Ovulation induction by pulsatile intravenous administration of Gn-RH to patients with hypothalamic amenorrhea].

Intravenous pump administration (Zyklomat, Ferring) of GnRH (Lutrelef, Ferring) has been used to induce ovulation in 16 patients suffering from hypothalamic amenorrhea between January 1989 and December 1991. One to 6 cycles were performed for a total of 47 cycles. GnRH pulses were set at 20 micrograms/pulse every 90 min up during the follicular phase and decreased to 1 pulse/120 min during the 3-5 days following ovulation. Thereafter, the luteal phase was supported by 1000 IU HCG/48 h up to the end of the 5th week. Response to the treatment was monitored with seriC E2, P and LH and vaginal echography. Cycles (N = 3) were cancelled when E2 did not reach at least 0.25 nmol/l after 30 days. An E2 level > 0.8 nmol/l, associated with a mature follicle (> 20 mm), and the presence of a LH peak or an increased progesterone level were used to determine the day of ovulation. In case of normozoospermy (N = 9), sexual intercourse was recommended to the patients (27 cycles), whereas an intrauterine insemination was performed in case of a male factor (N = 7, 20 cycles). Results can be summarized as follows: 39 (83%) cycles were ovulatory and led to 9 (19%) clinical and 6 (13%) biochemical pregnancies. Five (8.5%) pregnancies aborted and 5 (11%) came to full term. After exclusion of the male factors, the pregnancy rate reaches 26%/initiated cycle, 28%/ovulatory cycle and 56%/patient. No patient developed a hyperstimulation syndrome or a multiple pregnancy. Three cycles (6.3%) were interrupted due to 2 superficial phlebitis and 1 pump failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Follicle-stimulating hormone bioactivity in idiopathic normogonadotropic oligoasthenozoospermia: double-blind trial with gonadotropin-releasing hormone.

OBJECTIVE: To identify, among patients with idiopathic normogonadotropic oligoasthenozoospermia, those with low bioactive follicle-stimulating hormone (FSH), possibly because of inadequate gonadotropin-releasing hormone (GnRH) pulsatility, whose bioactive FSH and sperm could be improved by GnRH treatment. DESIGN: Randomized, double-blind, placebo-controlled trial with intranasal (IN) GnRH, followed by open GnRH treatment. SETTING: Outpatient endocrinology clinic. PATIENTS: Twenty-eight infertile men with idiopathic normogonadotropic oligoasthenozoospermia. INTERVENTIONS: Gonadotropin-releasing hormone or placebo was self-administered IN every 2 hours. MAIN OUTCOME MEASURES: Serum immunoreactive and bioactive FSH and semen analyses. RESULTS: Ten men showed a low basal FSH bioactive/immunoreactive ratio, which increased in 5 of them under GnRH without parallel sperm modification. Sperm improvements were observed in 10 patients with no parallel evolution of FSH bioactive/immunoreactive ratio. Unpredicted by sperm changes, three pregnancies developed on placebo and 5 on GnRH. CONCLUSIONS: Low bioactive FSH was not the cause of idiopathic normogonadotropic oligoasthenozoospermia in our patients and could not predict response to GnRH. Pulsatile GnRH did not improve sperm beyond random fluctuations.

Administration, Intranasal↗
PubMed1992

Immunofluorescence study of actin, acrosin, dynein, tubulin and hyaluronidase and their impact on in-vitro fertilization.

Using polyclonal antibodies, the distribution of actin, acrosin, dynein, tubulin and hyaluronidase has been examined by indirect immunofluorescence in sperm preparations from fertile donors and in-vitro fertilization (IVF) patients. After recording sperm parameters in native semen, spermatozoa were washed free of seminal plasma using either the swim-up or the Percoll filtration technique. Prior to insemination, aliquots of the washed sperm suspensions were prepared for antibody staining. Spermatozoa from fertile donors were analysed in order to establish the specific fluorescence patterns of each antibody and the threshold scores of normality. Immunofluorescence scores obtained from IVF patients were then analysed with respect to IVF outcome. For each tested protein, the number of normal samples were significantly lower in the group which did not fertilize and fertilization rates were significantly reduced when any of the tested proteins were scored as pathological. Normal fluorescence scores were correlated with morphology, motility, velocity and to a lesser extent with sperm concentration in native semen. On the basis of receiver-operating characteristic curves, likelihood ratios and Cohen's kappa values, the presence of acrosin and tubulin yields the most useful information on sperm functional and structural status and on its fertilizing ability.

Acrosin↗
PubMed1990

[Fertilization in vitro and embryo transfer].

After a brief historical survey and review of the main Swiss centres engaged in medically assisted procreation, the indications for in vitro fertilization and embryo transfer (IVF-ET) are discussed. This technique offers the sterility specialist a new approach in allowing separate investigation of the two gametes and study of their interactions. This therapeutic approach to infertility is thus supplemented by biological data which may modify or highlight some of the etiologic aspects and promote new treatments. The techniques employed at our centre and the results obtained over the past four years are presented. Analysis of IVF pregnancies shows that the obstetric risks can be associated with the characteristics of the groups treated rather than with the IVF technique.

Corpus Luteum Maintenance↗
PubMed1990

Why lose an in vitro fertilization cycle when stimulation fails?

Different protocols using agonists of GnRH-a have been proposed for the ovarian stimulation in IVF cycles. In case of stimulation failure with the flare-up protocol, we have investigated whether an immediate switch to pituitary blockade by the long-acting analog may avoid the cycle to be canceled. This procedure allows a rescue of cycles among poor responders and does not have any deleterious effect on the recruitment of follicles, oocyte quality, fertilization, and pregnancy rates.

Adult↗
PubMed1989

[The syndrome of ovarian hyperstimulation].

The ovarian hyperstimulation syndrome (SHO) can be defined as an iatrogenic pathology induced by active substances administered for controlling follicular maturation and ovulation. The etiology, the physiopathology, the diagnostic and therapeutic methods available are discussed. A theoretical model, based on clinical data, allows identification of a set of criteria which should help determining prospectively the chances of development of such a pathology.

Chorionic Gonadotropin↗
PubMed1984

Early phlebographic results after iliofemoral venous thrombectomy.

The results of conventional venous thrombectomy performed in 37 patients with acute iliofemoral thrombosis were evaluated with special reference to early postoperative phlebography. In all patients thrombosis was verified preoperatively by angiography. No mortality was encountered, but the leg of one patient with phlegmasia coerulea dolens and advanced venous gangrene had to be amputated at the above-knee level. Four patients had pulmonary embolism in relation to surgery. Based upon postoperative phlebography, complete clearance of all obstructed segments was achieved in 5 patients only (13.5%), and subtotal or partial restoration resulted in 9 patients (24%). In 16 cases (43%) postoperative phlebograms appeared equivalent to the preoperative study, and in 7 cases (20%) additional vein segments were occluded. Despite the relatively high incidence of recurrent thrombosis, prompt relief of symptoms occurred in the great majority of patients. The more favorable angiographic results were obtained in the ilio-femoral segment; in contrast, new occlusions were predominantly found in the popliteal-crural segments. Restoration of a venous passage was not correlated with the duration of symptoms; in most instances, the removed clots appeared organized and adherent to the vein intima, even in patients with a short clinical history. With regard to probable etiological factors, somewhat better results were achieved for patients exposed to previous surgery or trauma and for patients with severe medical illness. In our view indications for venous thrombectomy should be rather restrictive; successful clearance and long-term patency can be expected mainly in patients with clots lying in the ilio-femoral segment surrounded by contrast medium in the distal portion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Antithrombin III and related parameters in surgical patients receiving blood components.

We examined the intra- and postoperative behavior of antithrombin III (AT), factor V, VIII, and fibrinogen in 27 elective surgical patients without evidence of disseminated intravascular coagulation (DIC) and treated according to the concept of blood component therapy inaugurated at our hospital in 1975. The intraoperative depletions of AT and fibrinogen were proportional to the transfusion volumes and correlated significantly. AT, fibrinogen, and especially factor V and VIII were significantly mobilized during surgery. A greater intraoperative depletion of AT was significantly associated with a faster recovery during the first 24 postoperative h. The AT activity was virtually stable over a period of 4 weeks in CPD-adenine red cell concentrates; fresh frozen plasma and whole blood are thus not essential as a source of AT. The application of our concept did not increase the frequency of thromboembolic complications, despite the fact that the intraoperative AT values fell below the presumed 'critical' level of 60-70% in some patients. The probable reasons are the brief duration of such levels, the simultaneous depletion of coagulation-promoting plasma constituents (e.g. fibrinogen), and the use of antithrombotic prophylaxis. Our results suggest no reasons for a routine use of fresh frozen plasma in patients with a loss and replacement of less than about 75% of their blood volume.

Antithrombin III↗
PubMed1981

Influence of a blood component program on postoperative complication rates: a retrospective study in 372 patients.

We did a retrospective study of 372 thoracic and cardiovascular surgery patients, except open heart cases, which were treated by the same senior staff during the last year before (N = 197) and the first year after (N = 175) the introduction of a blood component program. There were no other basic changes of therapeutic policies. The two populations were comparable with respect to various basic characteristics. During the period 'before' the large majority of red cell units was 'deplasmatized' blood with a plasma deficit of 100 ml and a hematocrit of 40%. During the period 'after' it was red cell concentrates with a plasma deficit of 200 ml and a hematocrit of 70%. The usage pattern of red cell units did not change. The only statistically significant (and deliberate) quantitative difference between the transfusion regimens 'before' and 'after' was a more extensive intraoperative use of a gelatin plasma substitute to balance the plasma deficit of the red cell concentrates. As judged by various criteria, the postoperative courses of the patients 'before' and 'after' were virtually indistinguishable. We conclude that the blood component program practised at our hospital has no adverse effects on the postoperative course.

Adult↗