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Biomedical subjects

W Feichtinger

Publications and source records attributed to W Feichtinger.

At least 73 records · Page 4Linked to original sources
PubMed1993

Chromosome banding in Amphibia. XVIII. Karyotype evolution and genomic size variation in Pleurodema (Anura, Leptodactylidae).

DNA flow cytophotometric measurements demonstrate that the quantity of nuclear DNA of the South American leptodactylid frog Pleurodema brachyops is 3.4 times greater than that of P. thaul. Nevertheless, the conventionally stained karyotypes of both species are nearly identical. In the metaphase chromosomes of P. brachyops, the chromatin has a distinctly higher degree of packaging than in those of P. thaul. C-banding reveals that almost 6 times the constitutive heterochromatin is present in the karyotype of P. brachyops than in the karyotype of P. thaul. Analysis of fluorescence banding patterns shows that the chromosomes of P. brachyops contain AT- and GC-rich heterochromatin, whereas the karyotype of P. thaul is devoid of brightly fluorescing heterochromatin. The substantial differences in the genome sizes of Pleurodema is explained by homogeneous, symmetrical changes in the amounts of all DNA sequence classes along all chromosomes, which preserved the ancestral morphology of the chromosomes.

Animals↗
PubMed1993

[Micromanipulation of human gametes within the scope of assisted reproduction].

Poor function of spermatozoa accounts for half of all human infertility. Micromanipulation methods within the framework of in vitro fertilization treatment may enhance fertilization of the egg and may allow the establishment of an ongoing pregnancy in cases of severe male infertility. This review presents different methods of micromanipulation which are routinely applied in male factor infertility and for preimplantation diagnosis.

Embryo Implantation↗
PubMed1993

[Ovarian hyperstimulation syndrome].

The ovarian hyperstimulation syndrome (OHSS) is caused iatrogenically by the application of agents for ovulation induction. The syndrome may be characterized by different symptoms sometimes including an increase in blood viscosity, changes in coagulation parameters as well as renal perfusion. Although the incidence of the severe forms of the syndrome is very low, there is a general increase due to the wide spread use of ovulation induction. The only treatment of the syndrome is prevention by close monitoring of serum oestradiol levels and follicular development.

Ascites↗
PubMed1992

Fragile site (16) (q22). III. Segregation analysis.

The rare autosomal fragile site, fra (16) (q22), is the most common of all rare autosomal fragile sites and has a heterozygote frequency of about 5%. Evidence for it was found following the segregation expected from a simple codominant trait with complete penetrance; this is in contrast to a variety of other rare autosomal fragile sites. Based on the analysis of 12 families in which fra (16) (q22) is segregating, we found that, whereas complete penetrance could be confirmed, the transmitting parent was significantly more likely to be of the female sex. On the other hand, there was no evidence for preferential transmission to offspring of either sex.

Chromosome Fragile Sites↗
PubMed1992

Chromosome banding in Amphibia. XVII. First demonstration of multiple sex chromosomes in amphibians: Eleutherodactylus maussi (Anura, leptodactylidae).

A cytogenetic study performed on a population of the South American leptodactylid frog Eleutherodactylus maussi revealed multiple sex chromosomes of the X1X1X2X2 female/X1X2Y male (= XXAA female/XXAY male) type. The diploid chromosome number is 2n = 36 in all females and 2n = 35 in most males. The multiple sex chromosomes originated by a centric fusion between the original Y chromosome and a large autosome. In male meiosis the X1X2Y (= XXAY) multiple sex chromosomes form a classical trivalent configuration. E. maussi is the first species discovered in the class Amphibia that is distinguished by a system of multiple sex chromosomes. Only one single male was found in the population with 2n = 36 chromosomes and lacking the Y-autosomal fusion. This karyotype (XYAA male) is interpreted as the ancestral condition, preceding the occurrence of the Y-autosome fusion.

Animals↗
PubMed1992

Early stages of sex chromosome differentiation in fish as analysed by simple repetitive DNA sequences.

Animal sex chromosome evolution has started on different occasions with a homologous pair of autosomes leading to morphologically differentiated gonosomes. In contrast to other vertebrate classes, among fishes cytologically demonstrable sex chromosomes are rare. In reptiles, certain motifs of simple tandemly repeated DNA sequences like (gata)n/(gaca)m are associated with the constitutive heterochromatin of sex chromosomes. In this study a panel of simple repetitive sequence probes was hybridized to restriction enzyme digested genomic DNA of poeciliid fishes. Apparent male heterogamety previously established by genetic experiments in Poecilia reticulata (guppy) was correlated with male-specific hybridization using the (GACA)4 probe. The (GATA)4 oligonucleotide identifies certain male guppies by a Y chromosomal polymorphism in the outbred population. In contrast none of the genetically defined heterogametic situations in Xiphophorus could be verified consistently using the collection of simple repetitive sequence probes. Only individuals from particular populations produced sex-specific patterns of hybridization with (GATA)4. Additional poeciliid species (P. sphenops, P. velifera) harbour different sex-specifically organized simple repeat motifs. The observed sex-specific hybridization patterns were substantiated by banding analyses of the karyotypes and by in situ hybridization using the (GACA)4 probe.

Animals↗
PubMed1992

Successful clinical application of laser for micromanipulation in an in vitro fertilization program.

This is a report of our preliminary experience with assisted hatching by laser with a case of an ongoing twin pregnancy. We used an erbium laser to create a 20 to 30-micrometer opening in the zona pellucida of human embryos to facilitate the embryonic hatching after the embryo transfer. Our report proves that it is possible to obtain a pregnancy using a simple and quick laser method instead of mechanical or chemical procedures within the scope of micromanipulation.

Adult↗
PubMed1992

[Transvaginal Doppler study of embryonic heart action in early pregnancy].

Embryonic cardiac activity was observed by means of transvaginal Doppler ultrasound in a period from the 28th through the 78th day after conception (p. c.). We were able to detect a correlation between the embryonic heart rate and the stage of pregnancy as well as a correlation to the crown-rump length. The maternal age did not seem to have any effect on the appearance of embryonic heart activity. The number of registered Doppler echoes did not yield information on embryonic heart development.

Adult↗
PubMed1992

The use of fibrin sealant for embryo transfer: development and clinical studies.

Many embryo transfers after in-vitro fertilization may fail because of expulsion of the embryos from the uterus. Approximately 5-8% of pregnancies resulting from embryo transfer are ectopic. The aim of our study was to find a technique to avoid ectopic pregnancies and to improve the pregnancy rate. We used a two-component fibrin sealant which also contains a fibrinolysis inhibitor (aprotinin) at various concentrations. After gaining experience with mouse embryos, the sealant was used in human embryo transfer with great success. The results of a pilot study encouraged us to perform a prospective randomized study on 546 patients (270 with fibrin sealant, 276 conventional embryo transfers). There were 47 (17.0%) orthotopic pregnancies and 6 (2.2%) ectopic pregnancies in the control group, whereas there were 51 (18.9%) intrauterine and no ectopic pregnancies in the treatment group. The difference in ectopic pregnancies was statistically significant (P less than 0.05). With regard to the aprotinin concentration, there was a trend towards better results with 100-150 kIU (28.5% clinical pregnancies) in comparison to 250-300 kIU (19.2%) or no aprotinin (20.4%) (not significant). Further improvements of the technique may raise the pregnancy rate when fibrin sealant is used. As shown in our prospective randomized study, ectopic pregnancies may be completely avoided.

Adult↗
PubMed1992

'Chemical curettage' using intrauterine methotrexate injection.

A 22-year-old woman with multiple urogenital anomalies presented for the second time with a blighted ovum situated in the rudimentary right horn of a uterus communicans bicornis. A dilatation and curettage was not possible owing to the inaccessibility of this horn. The first blighted ovum was aborted in 1989 (at age 21 years) following the use of intramuscular prostaglandin therapy. On this occasion, therapy was by the transvaginal, intrauterine (intra-amniotic) instillation of 100 mg methotrexate and a complete abortion of the products of conception occurred. Similar to the treatment of ectopic pregnancy, in certain cases, termination of intrauterine pregnancies using local methotrexate injection may be considered.

Abortion, Therapeutic↗
PubMed1992

An intriguing Y chromosome in Heteromys anomalus (Rodentia, Heteromyidae).

The mitotic chromosomes of the pocket mouse Heteromys anomalus (Rodentia, Heteromyidae) from Venezuela were analyzed by means of conventional staining and various banding techniques. The karyotype of this species is distinguished by a Y chromosome with exceptional banding properties. The very large heterochromatic Y long arm shows a remarkable bright quinacrine fluorescence, but only moderate or dull fluorescence when labeled with other AT base pair-specific fluorochromes. The implications of these findings are discussed.

Animals↗
PubMed1992

Current technology of oocyte retrieval.

Transvaginal follicle puncture under sonographic control has become the method of choice for ovum retrieval worldwide. Because it is the current technology of the 1990s, there are very few reports in the literature on other methods of oocyte retrieval. Furthermore, perhaps because of the simplicity of transvaginal follicle puncture under sonographic control, there are only a few reports on the technique itself in the current literature. This review classifies the papers on hand according to general studies of the subject, appropriate anesthesia, necessity of follicle flushing for oocyte retrieval, vaginal disinfection and the evaluation of the risk following transvaginal oocyte retrieval, and new techniques in connection with the harvesting of oocytes.

Anesthesia↗
PubMed1991

Prognostic appraisal of success and failure in an in vitro fertilization program by transvaginal Doppler ultrasound at the time of ovulation induction.

In 323 stimulated cycles of women participating in in vitro fertilization treatment, a transvaginal Doppler examination was performed on the day of ovulation induction to investigate the value of blood flow velocimetry of the uterine artery. The results showed a significantly lower pulsatility index in patients who conceived (n = 42) compared with those who did not become pregnant (n = 272). The differences were especially marked during the first cycles. These results suggest that studies of the uterine hemodynamic response are useful in appraising the likelihood of success of implantation after embryo transfer.

Journal Article↗