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Biomedical subjects

R Hauser

Publications and source records attributed to R Hauser.

207 records · Page 12Linked to original sources
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Oral immunization of wildlife against rabies: concept and first field experiments.

The possibility of immunizing carnivores against rabies with live attenuated vaccine administered by the oral route was raised by North American scientists in the 1960s. Subsequently, several American and European teams tested different vaccine strains in the laboratory for efficacy and safety and studied vaccine stabilization, vaccine delivery systems, bait acceptance by wild animals, and bait distribution schemes. The first field trial of a cloned SAD (Street Alabama Dufferin) strain in baits designed to immunize foxes orally was conducted in an Alpine valley in Switzerland in 1978. A population containing approximately 60% immune foxes at the valley entrance stopped the spread of the disease into untreated upper parts of the valley. The strategic use of oral vaccination of foxes in additional regions of Switzerland resulted in freedom from the zoonosis in four-fifths of the country.

Administration, Oral↗
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Varicocele: effect on sperm functions.

Despite the numerous studies published over the past decade, the role of varicocele in male infertility is still controversial. Although more frequent in infertile men, its influence on sperm production or function has not, as yet, been determined. Moreover, the exact mechanism of varicocele action is not clear. We have surveyed the literature, the correlation of varicocele to sperm parameters and to sperm function tests, such as binding capacity, hypo-osmotic swelling test, presence of reactive oxygen species, and in particular, the correlation to fertility potential. Almost every subject examined had contradictory results. Larger control studies may possibly elucidate and clarify the cases in which varicocele is associated to sperm function, and where treatment may improve fertility.

Acrosome Reaction↗
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Advanced methods for evaluation of sperm quality.

Routine semen analysis includes measurements of sperm concentration, motility, and morphology. In our study, three additional tests were evaluated in relation to fertilization rate in an in vitro fertilization program: the freezing and hypo-osmotic swelling tests that evaluate the functional integrity and stability of the sperm membrane under extreme osmotic conditions, and migration sedimentation test that isolates high-quality motile sperm cells. The study was performed on semen delivered by men of couples treated at the In Vitro Fertilization Unit, and men who served as semen donors (fresh or cryopreserved semen). No correlation was found between the sperm fertilization rate, and the decrease in motility percent following the freezing-thawing process. Thus, the freezing test cannot be used to predict semen fertilization capacity. The hypo-osmotic swelling test was applied on semen given by a similar population of men. While the hypo-osmotic swelling test values carried out with fresh semen was found to have good correlation with fertilization, no correlation was found when frozen thawed semen was used. Post-migration sedimentation test sperm characteristics, and especially the recovery rate of the motile sperm, were significantly better in in vitro fertilization cycles with fertilizations. Both the hypo-osmotic swelling test and migration sedimentation test can assist in evaluating semen quality, judged by the fertilization rate in an in vitro fertilization program.

Female↗
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Separation of sperm cells by sedimentation technique is not suitable for in vitro fertilization purposes.

Two methods of sperm preparation for in vitro fertilization were compared: the swim-up technique vs. the migration-sedimentation technique. The study comprised fresh semen samples obtained from 25 couples treated in the In Vitro Fertilization Unit. Oocytes aspirated in a single cycle were divided into two groups, each inseminated by sperm prepared by one of these techniques. Motility, degree of motility, and normal morphology were improved by both methods. The improvement was greater when the migration-sedimentation technique was applied. However, fertilization rate was significantly higher after the swim-up technique. In order to clarify this contradiction, an additional group of 26 semen samples was divided and then prepared by the swim-up or migration-sedimentation techniques. Sperm quality was examined up to 72 h after separation. Compared with the swim-up technique, sperm characteristics were better after separation by the migration-sedimentation technique. However, this difference abated after 24 h. The better results of the swim-up technique in the "survival experiment' may explain its improved performance in in vitro fertilization, despite lower separation capacity. Thus, the migration-sedimentation technique is not recommended for sperm preparation in in vitro fertilization.

Cell Separation↗
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Sperm binding and ultrasound changes after operative repair of varicocele: correlation with fecundity.

The study was conducted to evaluate the changes in sperm binding capacity and ultrasound measurements of the internal spermatic vein, after operative repair of a varicocele. In order to clarify the effect of a varicocele on fertility, these changes were correlated to pregnancy achievement. Twelve infertile males with subnormal semen parameters and varicocele, underwent operative repair. Pre- and post-operatively, all had semen analysis, hemizona assay and ultrasound of the internal spermatic veins. The patients were divided into three subgroups according to pregnancy outcome, and the changes in the different evaluation tests after the operation were compared. Sperm concentration and motility improved post-operatively in all three subgroups, whereas the hemizona index and ultrasonographic measurements improved significantly only in the subgroup that achieved early pregnancies (the mean post-operative percentage of normal morphology was significantly higher), compared to the subgroup without pregnancies. Unlike sperm parameters which improve after operative repair of the varicocele, but have no correlation to conception, sperm binding and ultrasound measurements of the internal spermatic veins improve significantly in cases that achieve early pregnancies. The use of these tests, as well as measuring the percentage of normal morphology, are recommended in all cases of infertility-related varicocele.

Female↗
PubMedDate not supplied

Correlation between sperm penetration into the human zona pellucida and in vitro fertilization rates.

Sperm penetration into the zona pellucida of unfertilized oocytes, and its correlation with in vitro fertilization rates of the sibling oocytes, were assessed. This was performed in order to evaluate the prediction rate of the sperm penetration test into the zona pellucida. Unfertilized oocytes (n = 1872) from 371 cycles were pipetted through a microcapillary, and the remaining sperm cells penetrating the zona pellucida were counted. The mean (+/- SD) number of spermatozoa that penetrated the zona pellucida of unfertilized oocytes was 12.9 +/- 16.37. A significant correlation was found between the fertilization rate and the mean number of spermatozoa that penetrated into the zona pellucida of the unfertilized sibling oocytes (r = 0.48; P < 0.001), or the percent of unpenetrated zonae pellucidae in a cohort (r = -0.43; P < 0.001). However, a distinct variation in the number of spermatozoa that penetrated into the zona pellucida was detected. A step-wise regression analysis proved the number of spermatozoa penetrating the zona pellucida to be more predictive for fertilization rates than the variable of percent of unpenetrated zonae pellucidae. The results imply that although there is interdependence between penetration into the zona pellucida and fertilization rate, the predictive value of sperm penetration test for prognosis and future management after the first in vitro fertilization attempt, is limited.

Cohort Studies↗
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Three-generation evaluation of Y-chromosome microdeletion.

Sperm cells can be retrieved directly from the testis (testicular sperm extraction [TESE] procedure) and used for intracytoplasmic sperm injection (ICSI), circumventing underlying spermatogenetic defects. Thus, it is important that added information be available on the genetic defects in men undergoing TESE for the ICSI procedure and on the transmission of genetic factors associated with infertility to the offspring. We report a three-generation genetic analysis of a family with a case of male factor infertility. The proband, previously diagnosed as infertile, was physically examined and laboratory tested for gonadotrophic hormones, semen analysis, karyotype and Y-chromosome microdeletion screening in the blood and testis. The Y-chromosome microdeletion screening was performed by multiplex polymerase chain reaction with 20 Y-chromosome sequenced, tagged sites located at the Y chromosome. A microdeletion including the AZF-c region was detected in the azoospermic patient. His father, four brothers, and three offspring born after ICSI also underwent Y-chromosome microdeletion screening. The genetic analysis of the male members of the patient's family did not reveal similar microdeletions. The newborn male was found to bear a Y-chromosome microdeletion similar to that of his father. The fertilization capacity of the proband testicular microdeleted spermatozoa by the ICSI procedure is described. The transfer of the genetic defect raises the possibility that the son will have the same fertility problem as his father.

Adult↗
PubMedDate not supplied

Morphology of testicular spermatozoa obtained by testicular sperm extraction in obstructive and nonobstructive azoospermic men and its relation to fertilization success in the in vitro fertilization-intracytoplasmic sperm injection system.

The aim of the present study was to evaluate the morphology of testicular spermatozoa by 3 different determinants. Sperm cells were obtained and their morphology was evaluated from 27 testicular sperm extraction (TESE) operations, of which 20 men had nonobstructive azoospermia and 7 had obstructive azoospermia. In 17 cases, 2 biopsies were obtained from 2 different locations of the testis. Only mature spermatozoa presenting full-grown tail (tail dimension about 10-fold greater than the head dimension) were counted. Three characteristics of sperm morphology were evaluated: head dimensions, and acrosome and midpiece irregularities. The percentage of sperm cells with normal morphology (considering the 3 characteristics) in specimens from patients with obstructive and nonobstructive azoospermia were 47% +/- 4.6% and 29 +/- 1.8%, respectively (P < .01). The percentage of spermatozoa with normal head dimensions were 76% +/- 3.2% and 63% +/- 2.6% (P > .05), those with normal acrosome were 58% +/- 4.6% and 41% +/- 3.4% (P < .05), and those with normal midpiece were 74% +/- 4.1% and 67% +/- 1.6% (P > .05), in obstructive and nonobstructive azoospermia, respectively. No significant differences were observed in sperm morphology between different locations of the testis. Sperm morphological characteristics were not associated with fertilization rate in intracytoplasmic sperm injection (ICSI). Follicle-stimulation hormone and luteinizing hormone were inversely correlated with normal morphology of testicular spermatozoa (r = -0.49 and r = -0.47, respectively; P < .05). It can be concluded that a relatively high portion of testicular sperm are morphologically normal. The higher rate of normal spermatozoa in obstructive azoospermia compared with nonobstructive spermatozoa suggests that the factors leading to azoospermia may affect testicular sperm morphology. The morphological characteristics of testicular sperm do not affect fertilization rate in ICSI.

Adult↗