Dynamic left ventricular outflow tract obstruction in apical ballooning syndrome (Takotsubo cardiomyopathy).

Patients with apical ballooning syndrome may develop dynamic left ventricular outflow obstruction due to systolic anterior motion of the mitral valve leaflet and secondary functional mitral regurgitation, causing decreased cardiac output and hypotension. If suspected, bedside echocardiography will quickly confirm this complication. Positive inotropic/chronotropic agents should be avoided as they may exacerbate outflow tract obstruction, resulting in further hemodynamic compromise.

Mer22-related sequence elements form pericentric repetitive DNA families in primates.

We describe a novel repetitive DNA element isolated from three primate species belonging to the family Cercopithecidae. The unusually long 2.6-kb repeat unit of this DNA element is present in high copy number in the pericentromeric region of one pair of chromosomes in both baboon and macaque, forming chromosome-specific satellite-like DNA families. Besides these two very closely related species, the novel DNA element was also detected in the more distantly related African green monkey. However, the copy number of the repeat unit in this species is significantly lower than in macaque and baboon. Sequence analysis revealed that the repeat units of the new repetitive element show similarity to the human MER22 repeat and the Y chromosome-specific TTY2 element, which also exhibits retroelement-like features. Database searches indicate that tandemly arranged MER22-related DNA sequences can also be found in human, raising the possibility that these DNA elements may correspond to a novel primate-specific repetitive DNA group. Recent studies indicate that chromosome-specific pericentric repetitive elements, besides their potential involvement in centromere function, also facilitate homolog recognition during meiosis. In addition, rapid expansion of retroelements in the pericentric regions of chromosomes during interspecific hybridization has been described. In light of these data, we hypothesize that the novel repetitive element described here might have been involved in the speciation of the family Cercopithecidae.

Cytogenetic and fertility studies of a rheboon, rhesus macaque (Macaca mulatta) x baboon (Papio hamadryas) cross: further support for a single karyotype nomenclature.

Historically, two different numbering systems have been used to describe the baboon and macaque karyotypes. However, G-banding studies and, more recently, fluorescence in situ hybridization results have shown that the two karyotypes are virtually identical. To confirm this hypothesis, cytogenetic analysis of an unusual animal, a rheboon, was undertaken. The rheboon reported here, an 18-year-old male, is the only long-term survivor of 26 pregnancies resulting from matings between female baboons (Papio hamadryas) and male rhesus macaques (Macaca mulatta). A G-banded karyotype was prepared from the rheboon and compared with the karyotypes of the two parental species. Spectral karyotyping (SKY) was carried out on the rheboon chromosomes, and the results were compared with SKY studies reported for the baboon and with CISS (chromosome in situ suppression) studies in the rhesus macaque. No differences were detected in any of the rheboon's pairs of autosomes, reinforcing the apparent identity of the two parental karyotypes. Based on these results, we argue that a single karyotyping system should be adopted for the two species. Fertility studies were initiated to determine if the rheboon is sterile, as are most hybrid animals. Two semen ejaculates were devoid of sperm. A testicular biopsy revealed hypoplasia of the seminiferous tubules with few Leydig cells and large lumena. Meiotic arrest occurred during meiosis I, resulting in absence of mature spermatozoa. Thus, the testicular and meiotic findings in the rheboon were similar to those observed in other hybrids, even though the parental karyotypes appear identical.

Cytogenetic changes in radiation-induced tumors of the thyroid.

Thyroid carcinoma incidence is increased significantly after ionizing irradiation; however, the possible mechanisms have not yet been identified. To provide clues for an understanding of the radiation-induced transformation of thyroid epithelium, we analyzed the karyotypes of 56 childhood thyroid tumors that appeared in Belarus after the Chernobyl nuclear accident in 1986. We also studied eight secondary thyroid tumors that developed after radiotherapy. Metaphase preparations obtained from primary cultures were analyzed by G-banding. Clonal structural aberrations were found in 13 of 56 Belarussian cases and in 6 of 8 secondary tumors that developed after radiotherapy. Furthermore, we detected multiple chromosomal aberrations as well as complex rearrangements in some of these tumors and performed a detailed analysis of marker chromosomes from a single case using spectral karyotyping and comparative genomic hybridization in a childhood tumor from Belarus with a near-triploid karyotype. Both comparative genomic hybridization and spectral karyotyping analysis revealed structural alterations affecting identical chromosomes 1, 2, 9, and 13, among others. In addition to the known hot spots of alterations in papillary thyroid carcinomas on chromosomes 1q and 10q, a comprehensive breakpoint analysis in the pooled data set revealed novel breakpoints on chromosomes 4q, 5q, 6p, 12q, 13q, and 14q. The chromosomal aberrations in these tumors may provide suitable starting points for the positional cloning of genes involved in radiation-induced tumorigenesis.

3-Bromoacetylamino benzoylurea (3-BAABU), a new antimicrotubule cancericidal agent applied in cytogenetic analysis in hematology.

3-Bromoacetylamino benzoylurea (3-BAABU) is a newly synthesized antimicrotubule cancericidal compound. In the present study, we investigated the possibility of using 3-BAABU as a mitotic blocking agent for hematologic karyotyping. Treatment with 3-BAABU caused scattering of metaphase chromosomes throughout the cytoplasm both in phytohemagglutinine (PHA)-stimulated human lymphocytes and in human leukemic cells. Kinetic showed a rapid uptake of 3-BAABU by treated cells and irreversibility of its effect. Using 3-BAABU in routine procedure, a karyotype of lymphocytes from a normal male was 46, XY, with normal structure and CEM leukemic line was 85, XX, in a representative spread with abnormalities similar to reports using other blocking agents. Using 3-BAABU in spectral karyotyping, details of translocations in CEM leukemic cells were readily detected in several chromosomes, such as 7 [t(7;11)], 8 [t(8;9)], 9 [t(8;9) & t(9;19)], 11 [t(7;11)], 16 [t(16;18;20)] and 20 [t(1;20)]. 3-BAABU displayed two important characters in cytogenetics, 1) it caused dispersion of chromosomes, avoiding chance of overlap; 2) compared to the conventional mitotic blocking agent, vinblastine sulfate, 3-BAABU exhibited much gentle effect on chromosomes, thus providing more flexibility in time to perform karyotyping.

Baboon/human homologies examined by spectral karyotyping (SKY): a visual comparison.

Baboon (Papio hamadryas) metaphase chromosomes were analyzed using spectral karyotyping (SKY), a technique combining fluorescence microscopy, CCD-imaging, and Fourier spectroscopy. Results from a comparison of SKY analyses using probes derived from human chromosomes on baboon metaphases were consistent with the majority of comparative gene mapping data between the two species. These data were also compatible with earlier studies comparing macaque and human chromosomes. Human (HSA) chromosome 2 was homologous to baboon (PHA) chromosomes 12 (HSA 2q) and 13 (HSA 2p), whereas three baboon chromosomes corresponded to two different human chromosomes: PHA 3 to HSA 7 and HSA 21, PHA 7 to HSA 14 and HSA 15, and PHA 10 to HSA 20 and HSA 22. These results support the retained synteny between the Hominidae and Cercopithecidae genomes.