RESUMO
It was theoretically predicted earlier that if a periodic force without constant component is applied to a particle, then the particle can produce a directed drift in some direction. The effect is named nonlinear electrofrictiophoresis, because it is crucial for its appearance that the friction force depends on the particle's velocity in a nonlinear manner. We test a possibility to observe this effect when a mixture of fragments of DNA (the DNA ladder) moves in the agarose gel. For this purpose, we study the nonlinear characteristics of a DNA ladder movement in the gel. The gels with the ladder were run under various electric field strengths. It was found that the friction coefficient for each DNA fragment in the ladder depends on the migration velocity, suggesting that energy dissipation during migration is a nonlinear function of velocity. This nonlinearity makes the system under consideration suitable for observing nonlinear electrofrictiophoresis. A possible velocity of directed drift under periodic electric drive without constant component was estimated numerically for experimentally observed dependencies. The velocity appeared to be comparable with that of migration under a constant field of moderate strength. A possible mechanism of energy dissipation during movement of DNA through the gel is discussed.
Assuntos
Eletroforese em Gel de Ágar/métodos , Raios UltravioletaRESUMO
Recent sibling-pair linkage analyses have indicated possible linkage of noninsulin dependent diabetes mellitus (NIDDM) with a number of markers on the long arm of chromosome 7. A coincidental and recent discovery is that specific genetic anomalies identified on chromosome 7 in uterine leiomyoma tumor cells in many cases correspond, cytogenetically, to the same region where genetic linkage to insulin resistance has been identified. In the present study, 15 closely spaced microsatellite markers were used to finely map deletion breakpoints and to test for allelic loss of 7q markers in 12 uterine leiomyoma tumor samples with cytogenetically defined deletions. Of the 9 informative tumor samples, three exhibited breakpoints in the same region where genetic linkage to insulin resistance has been identified (between PON and UT901). Because breakpoints in neoplasias often occur within or adjacent to expressed sequences, these breakpoints may provide a molecular tool to aid in the identification of candidate genes for insulin resistance.
Assuntos
Cromossomos Humanos Par 7 , Ligação Genética , Resistência à Insulina/genética , Leiomioma/genética , Neoplasias Uterinas/genética , Diabetes Mellitus Tipo 2/genética , Feminino , Marcadores Genéticos , Humanos , Perda de HeterozigosidadeRESUMO
We report the cytogenetic findings in three mixed liposarcoma following short-term cultures. During the course of cytogenetic investigation of various types of liposarcomas, we observed an interstitial deletion of the long arm of chromosome 6 together with the translocation (12;16)(q13;p11) in three tumors. Translocation (12;16) is associated with myxoid and mixed (myxoid/round cell) liposarcomas, although deletion of chromosome 6 has been observed in only a few of these tumors. Our findings suggest that del(6), as an additional change in myxoid liposarcoma, is probably related to tumor progression.
Assuntos
Cromossomos Humanos Par 12 , Cromossomos Humanos Par 16 , Cromossomos Humanos Par 6 , Deleção de Genes , Lipossarcoma/genética , Neoplasias de Tecidos Moles/genética , Translocação Genética , Adulto , Idoso , Feminino , Humanos , Cariotipagem , Masculino , Pessoa de Meia-IdadeRESUMO
A translocation between chromosomes 6 and 10 was observed in two uterine leiomyomas. Translocation (6;10) may be important in the pathogenesis of a subgroup of uterine leiomyomas.
Assuntos
Cromossomos Humanos Par 10 , Cromossomos Humanos Par 6 , Leiomioma/genética , Translocação Genética , Neoplasias Uterinas/genética , Adulto , Feminino , Humanos , Cariotipagem , Pessoa de Meia-IdadeRESUMO
BACKGROUND: The majority of karyotypes observed in osteosarcomas (OS) and chondrosarcomas (CS) are complex. Specific chromosomal abnormalities have not yet been characterized in either tumor except for a ring chromosome in parosteal OS. The purpose of this study was to determine recurrent chromosomal abnormalities and establish a possible correlation between the cytogenetic changes and the pathologic findings. METHODS: Ten OS and nine CS were cytogenetically analyzed. Tumor samples were obtained from patients having a resection or incisional biopsy. Cytogenetic study of short term cell cultures included harvesting and G-banding, which were performed by routine methodologies. RESULTS: Clonal abnormalities were observed in six OS and six CS. Modal chromosome numbers ranged from near diploid to near tetraploid in both types of tumors. The structural rearrangements observed in OS involved mostly chromosomes 1, 2, 6, 12, and 17. Nonreciprocal translocations were the most frequent event. Two OS had a single clonal abnormality involving 11p15 and 14q32, respectively. Double minute chromosomes were observed in three cases. In CS, the most frequent structural abnormalities were nonreciprocal translocations and deletions involving numerous chromosomes. Rearrangements of 1p together with other abnormalities were observed in four CS. CONCLUSIONS: The karyotypes were usually complex consisting of numerical and structural changes, particularly in high grade tumors. Rearrangements of 11p15 and 14q32 in OS and possibly 1p in CS were found as primary cytogenetic aberrations. Cytogenetic analysis in more cases of OS and CS together with molecular studies are necessary to characterize further the consistent genetic changes in these tumors.
Assuntos
Neoplasias Ósseas/genética , Condrossarcoma/genética , Aberrações Cromossômicas , Transtornos Cromossômicos , Osteossarcoma/genética , Adolescente , Adulto , Idoso , Neoplasias Ósseas/patologia , Criança , Condrossarcoma/patologia , Feminino , Humanos , Cariotipagem , Masculino , Pessoa de Meia-Idade , Osteossarcoma/patologia , PloidiasRESUMO
Cytogenetic analysis was performed on 21 tumor samples of malignant melanoma to identify the presence of consistent chromosome abnormalities. Four cases had a normal karyotype, and 17 were cytogenetically abnormal. Numerical chromosome alterations were observed in 15 tumors: 12 were hyperdiploid and three were hypodiploid. The most frequent losses consisted of chromosomes 5, 9, 17 and Y. The structural abnormalities were usually complex, consisting mainly of nonreciprocal translocations and deletions affecting 1p, 1q, 3p, and 9p. This study adds further data to previously reported melanoma cases, confirming that chromosomes 1, 3, 6, and 9 are nonrandomly affected.
Assuntos
Aberrações Cromossômicas , Melanoma/genética , Neoplasias Cutâneas/genética , Adulto , Idoso , Cromossomos Humanos 1-3 , Cromossomos Humanos 6-12 e X , Cromossomos Humanos Par 17 , Feminino , Humanos , Cariotipagem , Masculino , Pessoa de Meia-Idade , Cromossomo YRESUMO
A 60-year-old woman who presented with weakness, night sweats, bone pain, easy bruising and weight loss was found to have ecchymoses and hepatosplenomegaly. Blood counts showed persistent neutrophilia of mature cell type with Döhle bodies and toxic granulation. Coexistence of chronic neutrophilic leukemia and multiple myeloma of kappa light chain type was documented by bone marrow examination and immunofixation.
