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E Ko

Publications and source records attributed to E Ko.

45 records · Page 3Linked to original sources
PubMed1992

Analysis of sperm chromosome complements from a man heterozygous for a robertsonian translocation 45,XY,t(15q;22q).

Chromosome complements were studied in 118 sperm from a man heterozygous for a 15;22 Robertsonian translocation using the human sperm/hamster oocyte fusion technique. Alternate segregation occurred in most spreads (89.6%) and the proportion of normal (42.6%) and balanced complements (47%) was approximately equal. The frequency of sperm that were unbalanced with respect to the translocation was 10.4% and all categories of unbalanced sperm were observed (-15, -22, +15, +22). The frequency of chromosome abnormalities unrelated to the translocation was 7.6%. Since the frequencies of both numerical (3.4%) and structural abnormalities (3.4%) were within the normal range of control donors, there was no evidence for an interchromosomal effect. The frequencies of X-chromosome bearing (48%) and Y-chromosome bearing (52%) sperm were not significantly different from 50%. Data on this translocation were compared to the 4 other reports of cytogenetic analysis in sperm of Robertsonian translocation carriers.

Adult↗
PubMed1992

A comparison of the frequency and type of chromosomal abnormalities in human sperm after different sperm capacitation conditions.

Human sperm karyotypes can be prepared after fusion of human sperm with Golden hamster oocytes. Most laboratories use one of two methods of sperm capacitation: incubation of freshly-ejaculated sperm in Biggers, Whitten, and Whittingham (BWW) medium for 5-7 h at 37 degrees C or sperm storage in (N-tris [hydroxymethyl]methyl-2-aminoethanesulfonic acid; 2-([2-hydroxy-1,1-bis(hydroxymethyl)ethyl]amino)ethanesulfonic acid) (TES)-Tris yolk buffer (TYB) for 1-3 days at 4 degrees C. Since there have been conflicting reports as to whether there is a difference in the frequency of structural chromosomal abnormalities between BWW capacitation and storage in TYB for 2 days, we analyzed a larger number of karyotypes (8974) from 136 donors to determine if there was any difference in the frequency or type of chromosomal abnormalities in sperm treated by fresh BWW capacitation, storage in TYB for 1 day (TYB-1), or storage in TYB for 2 days (TYB-2). There was no difference in the frequency of numerical chromosomal abnormalities or sex ratio in any of the three treatment groups. However, there was a significantly increased frequency of structural chromosomal abnormalities after storage in TYB-1 and TYB-2. There was no difference in the frequency or type of structural chromosomal abnormalities after sperm storage in TYB-1 compared to TYB-2.

Adult↗
PubMed1991

Distribution of aneuploidy in human gametes: comparison between human sperm and oocytes.

The frequency and distribution of aneuploidy was compared in 11,615 karyotyped human sperm and 772 karyotyped human oocytes to determine if all chromosomes are equally likely to be involved in aneuploid events or if some chromosomes are particularly susceptible to nondisjunction. The frequency of hypohaploidy and hyperhaploidy was compared among different chromosome groups and individual chromosomes for human sperm and oocytes. In general, hypohaploid chromosome complements were more frequent than hyperhaploid complements, in sperm and oocytes. The distribution of chromosome loss in the hypohaploid complements indicated that significantly fewer of the large chromosomes and significantly more of the small chromosomes were lost, suggesting that technical loss predominantly affects small chromosomes. A conservative estimate of aneuploidy (2 X hyperhaploidy) was approximately 3-4% in the human sperm and 18-19% in human oocytes. All chromosome groups were represented among hyperhaploid human sperm and oocytes. For human sperm, the observed frequency of hyperhaploidy equaled the expected frequency based on the assumption that the frequency of nondisjunction is equal for all chromosome groups, with two exceptions: group G and the sex chromosomes. Among individual chromosomes in human sperm, chromosomes 1 and 21 and the sex chromosomes had a significant excess of hyperhaploidy. For human oocytes, there were fewer hyperhaploid oocytes than expected for chromosome groups C and F and more than expected for chromosome groups D and G. Among individual chromosomes there was a significant excess for chromosome 21. These results indicate that all chromosomes are susceptible to nondisjunction but that chromosome 21 is particularly prone to aneuploidy in both human sperm and oocytes. They also demonstrate that sex chromosome aneuploidy is common in human sperm but not in human oocytes.

Aneuploidy↗
PubMed1990

Effect of culture conditions and media on the frequency of chromosomal abnormalities in human sperm chromosome complements.

Human sperm chromosomes can be visualized after fusion with hamster eggs. Most laboratories use one of two methods of sperm treatment for capacitation: incubation in a modified Krebs-Ringer medium (BWW) for 5-7 h at 37 degrees C or storage in a TES-Tris yolk buffer (TYB) for 24-72 h at 4 degrees C. To determine whether data from the two methods were comparable, we performed a series of controlled experiments on one normal donor in which ejaculates were split and one aliquot of sperm was capacitated in BWW for 5-7 h at 37 degrees C (fresh) and the second aliquot was capacitated in TYB for 48 h at 4 degrees C (TYB). After capacitation, the technique used to obtain human sperm chromosome complements was identical for both aliquots. Both fresh and TYB sperm were further subdivided into two groups, which were subjected to either a short (1 h) or a long (3 h) gamete coincubation in BWW. This experiment was performed to determine if the longer incubation in BWW might induce chromosomal fragile sites and breaks because of nutritional depletion of the medium. A total of 458 human sperm chromosome complements was analysed. There was no significant difference in the frequency of sperm chromosomal abnormalities or in the sex ratio in the sperm coincubated with eggs for a short (1 h) or long (3 h) time in BWW. When sperm pretreatments were compared, there was a significant increase in the frequency of total sperm chromosomal abnormalities after TYB storage compared to fresh treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Cytogenetic analysis of 400 sperm from three translocation heterozygotes.

Sperm chromosome complements were studied in three men who carried reciprocal translocations. A total of 400 sperm were karyotyped after in vitro penetration of hamster eggs: 217 sperm from t(2;9) (q21;p22), 164 from t(4;6)(q28;p23) and 19 from t(7;14) (q21;q13). All possible 2:2 and 3:1 meiotic segregations were observed for t(2;9) and t(4;6); for t(7;14) only 2:2 segregations were observed. For alternate segregations, the number of normal sperm was not significantly different from the number of sperm carrying a balanced form of the translocation in any of the translocations, as theoretically expected. The percentage of sperm with an unbalanced form of the translocation was 57% for t(2;9), 54% for t(4;6) and 47% for t(7;14). There was no evidence for an interchromosomal effect in any of the translocations since the frequencies of numerical abnormalities (unrelated to the translocation) were within the normal range of control donors. The frequencies of X- and Y-bearing sperm did not differ significantly from 50%. Results from a total of 17 reciprocal translocations studied by sperm chromosomal analysis were reviewed.

Adult↗
PubMed1990

Sperm chromosome analysis in a man heterozygous for a reciprocal translocation 46,XY t(12;20)(q24.3;q11).

Sperm chromosome complements were studied in a man who carried a reciprocal translocation t(12;20)(q24.3;q11). A total of 113 spermatozoa were karyotyped after in-vitro penetration of hamster eggs. 2:2 and 3:1 meiotic segregations were observed with the following frequencies: alternate 47%, adjacent 1 42%, adjacent 2 10%, 3:1 2%. For alternate segregations, the number of normal spermatozoa (25) was not significantly different from the number of spermatozoa carrying a balanced form of the translocation (28), as theoretically expected. The proportion of spermatozoa with an unbalanced form of the translocation was 53%. There was no evidence for an interchromosomal effect since the frequencies of numerical and structural abnormalities (unrelated to the translocation) were within the normal range of control donors.

Adult↗
PubMed1990

[Surgical treatment of hypoplastic left heart syndrome: a successful case report].

A successful case of Norwood operation for a 5-day-old infant with hypoplastic left heart syndrome is reported. Norwood procedure and central shunting with a 4 mm PTFE tube was performed. Cerebral and coronary artery were perfused independently during reconstruction of aorta in order to shorten the time of circulatory arrest. Post operative UCG documented un-obstructive systemic output from the right ventricle, well regulated pulmonary arterial blood flow and widely patent interatrial communication. This baby was discharged the hospital 66 days after surgery. He has been clinically well for six month after the operation.

Anastomosis, Surgical↗
PubMed1988

Human sperm chromosome complements after microinjection of hamster eggs.

A technique was developed for microinjection of human spermatozoa into golden hamster (Mesocricetus auratus) eggs to obtain human pronuclear chromosome complements. Before microinjection the spermatozoa were treated by brief sonication or incubation in TEST-yolk buffer to reduce motility. Very few sperm chromosome complements developed after sperm treatment with sonication and the frequency of spermatozoa with structural chromosomal abnormalities was exceedingly high (91%). The majority of sperm chromosome complements analysed had multiple breaks and rearrangements. Sperm incubation in TEST-yolk buffer before microinjection provided more analysable sperm karyotypes with a significantly lower frequency of structural chromosomal abnormalities (39%, P less than 0.001). Our results therefore suggest that sonication induces structural chromosomal abnormalities in spermatozoa. Since the frequency of chromosomal abnormalities after microinjection was higher than after sperm fertilization of hamster eggs, it appears that microinjection per se may also increase the frequency of chromosomal abnormalities in spermatozoa. These results are based on small numbers and must be confirmed on larger sample sizes, but our study suggests that microinjection of spermatozoa into eggs should not be recommended for clinical use until fully evaluated.

Animals↗