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Chiasma counts and non-disjunction frequencies in a normal ram and in rams carrying the Massey I (t1) Robertsonian translocation.

Testicular material from a normal ram (54XY), three rams heterozygous (53XYt1) and one ram homozygous (52XYt1t1) for the Massey I (t1) translocation was examined. The autosomal non-disjunction in the normal ram was 2.0% compared to a mean of 6.1% in the heterozygous animals. In the homozygous animal there were adhesions of the tunica vaginalis to the cauda epididymidis and extensive spermatogenic arrest.

Animals↗

Consanguinity, non-disjunction, parental age and Down's syndrome.

The effect of consanguinity on the non-disjunction mechanism in Down's syndrome, was examined in 417 cytogenetically confirmed Down's syndrome patients. The incidence of parental and grandparental consanguinity was 17.5% (n = 73), while that of only parental consanguinity was 17.2% (n = 71). First cousin marriages occurred more frequently, than uncle-niece and 2nd cousin marriages. With regard to parental age, only the mean age difference between consanguineous couples significantly differed from non-consanguineous couples. The inbreeding coefficient did not differ between trisomy 21 and translocation Down's families. From this study, it is concluded that consanguinity does not predispose to Down's syndrome.

Adult↗

Two sibs with duplication of 4q31-->qter due to 3:1 meiotic disjunction and mild phenotype.

Two sibs with duplication of 4q31-->qter due to 3:1 meiotic disjunction and mild phenotype: Clinical and cytogenetic findings in two sibs with partial duplication of 4q31.3-->qter and 21q11.2-->pter are reported. These patients are rare cases of reoccurrence of those partial trisomies due to 3:1 segregation of a maternal balanced translocation. A review of the literature reporting cases of trisomy of the 4q31-->qter segment is also made; previously reported cases mostly in addition have deletions of other chromosomes resulting from adjacent segregation of balanced translocation. The findings of our study confirm the high risk for offspring with unbalanced rearrangements in women with reciprocal translocation involving acrocentric and short chromosome segments. The study also points out that duplication of 4q31-->qter may go along with only mild phenotypic findings if there is no significant additional aneuploidy of the other chromosome involved in the rearrangement.

Chromosomes, Human, Pair 21↗

Osteomyelitis of the pubic symphysis, abscess and late disjunction after delivery. A case report.

Infection of the pubic symphysis after delivery is rare, and probably occurs through a small vaginal laceration and is usually silent in the early phase: as the disease progresses, bone infection, sequestra formation and septicemia man occur. This report presents one case of staphylococcal osteomyelitis of the symphysis in a twenty five years old woman, with onset of symptoms 2 months after delivery. Staphylococcus Aureus was collected from pus and blood. Bone sequestra and a large abscess extending in the rectus abdominis fascia were present. Drainage and curettage resolved infection, but sourapubic pain persisted because of symphysis disjunction, and was treated by external pelvic fixation.

Abscess↗

Medico-legal knowledge of general practitioners: disjunctions, errors and uncertainties.

This article discusses a survey of Victorian general practitioners which investigated doctors' legal knowledge, the impact of law on clinical practice, doctors' current medico-legal information sources and their legal education needs and preferences. Knowledge of legal standards was investigated in relation to three areas: disclosure of risk; ownership of, and access to, medical records; and proxy decision-making. Additionally, the impact of statutory reform in relation to proxy decision-making was explored. Further, doctors' past experience of medico-legal education, current sources of medico-legal information and preferences concerning future medico-legal information were explored. Results indicated that overall, respondents had a very inadequate understanding of relevant law and that relevant statutory standards have had little impact on clinical practice. Professional bulletins and journals were identified as major current legal information sources, whilst printed materials, seminars and conferences were preferred sources of legal information. The authors conclude that there is a significant disjunction between legal standards and doctors' awareness of those standards, thereby creating a significant source of liability for doctors. Results highlight an urgent need to develop legal education programs for general practitioners based on doctors' identified needs and preferences.

Adult↗

Role of acrocentric cen-pter satellite DNA in Robertsonian translocation and chromosomal non-disjunction.

The centromeres and short arms of the human acrocentric chromosomes have in common several families of tandemly repeated DNA. Recent analyses have revealed that, within some of these families, clearly distinct subfamilies have evolved that are unique to one or a subset of the different acrocentric chromosomes. The existence and maintenance of subfamilies common to different chromosomes entail a process of regular exchange between the non-homologous chromosomes. This process is suggested for the evolution of an alpha satellite subfamily recently found on chromosomes 13, 14 and 21. The presence of this alpha subfamily may allow pairing between these chromosomes leading to the observed non-random participation of these chromosomes in t(13q14q) and t(14q21q) Robertsonian translocations. The available data also indicate a very similar molecular organisation of the cen-pter region for chromosomes 13 and 21. This latter feature may further allow the two chromosomes to undergo a relatively extensive degree of meiotic pairing (in a manner analogous to that seen in the pseudoautosomal regions of the X and Y chromosomes), thus predisposing these two chromosomes to errors in meiotic segregation and non-disjunction.

Centromere↗

[Modifications of Lefort I osteotomy. Pterygomaxillary disjunction by an inferior rotation of the maxilla].

This article reviews some of the complications associated with the use of a chisel to achieve separation of the pterygomaxillary region during the Lefort I osteotomy. A modification of this surgical procedure is proposed whereby no chisel is used to complete the maxillary disjunction. A series of more than 200 consecutive Lefort I osteotomies using this technique confirms the value of this modification.

Humans↗

[Preferential segregation of chromosome 21p- in 3 generations. Ultimate role in non-disjunction (apropos of a case of trisomy 21 in this family)].

A chromosome 21p- was observed in double dose in a trisomic 21 patient; the mother and other members of her family, in three generations, were carriers of this marker chromosome. After the analysis of similar families reported in the literature, the possible role of this marker in non disjunction and its segregation during meiosis is discussed.

Adult↗

[Occlusion of the common femoral artery by traumatic disjunction of the pubic bones. A case of late diagnois].

A case of tight but limited stenosis of the common femoral artery resulting from traumatic injury to the pelvis with disjunction of the pubic bones is reported. The lesion was initially overlooked and was only diagnosed 13 year later. Repair consisted of limited resection of the occluded arterial segment which was replaced by a Dacron graft. Such lesions of the external iliac/common femoral arteries appear to be rarely associated with traumas of the pelvis. In this particular case, the artery had probably been sheared by the iliopubic tract.

Adult↗

Solution structure of two molecular motor domains: nonclaret disjunctional and kinesin.

The effects of selected ligands on the structure of the truncated heavy-chain chemomechanical motor domains of Drosophila ncd and human kinesin were compared using the technique of transient electric birefringence. The 366-amino acid C-terminal motor domain of Drosophila nonclaret disjunctional, ncd(335-700), and the 349-amino acid N-terminal motor domain of human kinesin, kinesin(349), were studied at 4 degrees C in neutral buffers with ionic strength of 100 mM to form complexes with either MgADP or MgADP.Vi. The rotational diffusion time adjusted to 20 degrees C and water, tau 20,W, for ncd(335-700).MgADP is 32.8 ns, and for ncd(335-700).MgADP.Vi is 34.8 ns, suggesting prolate ellipsoids with dimensions 9.40 x 3.77 nm and 9.73 x 3.70 nm, respectively. The specific Kerr constant, Ksp, of ncd is -1.65 x 10(-12) cm2V-2 for the MgADP complex and -1.15 x 10(-12) cm2V-2 for the MgADP.Vi complex. The large negative Ksp for a prolate protein suggests an unusual charge distribution with two long surfaces with opposite charge. The tau 20,W for kinesin(349).MgADP is longer than the corresponding ncd motor and shows a decrease with increased electric field. The kinesin(349).MgADP.Vi complex has a longer tau 20,W. The Ksp for kinesin(349) is 0.36 x 10(-12) cm2V-2 for each complex.

Animals↗

Singular case of tardive anastomotic disjunction in a Dacron R vascular graft.

We investigated a case of anastomotic disjunction of the termino-lateral insertion of a bifurcate aortic graft in the right external iliac artery. The graft in woven Dacron R n. 19, was implanted in 1977 and the left femoral insertion became infected shortly after surgery. The infection was treated according to standard procedures with removal of the infected branch, reconstruction with the transobturatory by-pass and antibiotics. For antibiotic treatment of local and general sepsis the approach was completely new as regards dose regimen and duration. In 1993 a pseudoaneurysm developed through weakening of the right iliac anastomosis. In view of the anamnesis we were surprised to find that the origin was of a mechanical nature.

Aged↗

Anastomotic disjunction in long-term patent vascular synthetic grafts in Dacron.

This study follows the recently published paper on the in vivo behaviour of patent Dacron vascular prostheses and focuses in particular on anastomotic disjunction. The question of the evolution of anastomoses was tackled by examining its three basic components: prosthetic tissue, suture thread and arterial wall. The authors' observations were based on material taken from reoperations performed between 7 and 18 years after the first graft. These data enable the authors to affirm that the prosthesis undergoes a general physical and chemical deterioration which varies in intensity according to the type of weaving. On the contrary, in the anastomotic zone this phenomenon is not intense enough to jeopardize the anchorage of the suture thread since the original weft does not show any loss of compactness. In spite of surface morphological deterioration of various intensity, the suture threads maintain satisfactory mechanical properties and structural integrity. The artery wall in the anastomotic zone shows a massive degeneration in terms of its true anatomic structure responsible for the rupture of the suture rima. On the basis of these results the authors conclude that this phenomenon represents the "Achilles' heel" of anastomotic junction.

Aged↗

Cribra orbitalia in two temporally disjunct population samples from the Dakhleh Oasis, Egypt.

Cribra orbitalia (CO), an osseous sign of anemic stress, occurs in 67% (n = 296) of the pre-Roman (n = 153) and Roman (n = 143) period crania from the Dakhleh Oasis, Egypt. CO is primarily a childhood condition in these samples, and its prevalence is significantly higher in virtually all cohorts in the pre-Roman group, including among females, who display higher rates of active lesions. This temporal trend suggests that the underlying causative factors (i.e., synergism between disease and nutrition) were less pervasive in the Roman period. In both population samples, anemic stress develops in some perinates prior to the expected minimum age for the development of iron deficiency anemia. This suggests additional causes of anemic stress in the Dakhleh population. A strong candidate is folic acid deficiency and its concomitant, megaloblastic anemia, which results from weaning of infants on goat's milk, a known practice in ancient Egypt. The putative incorporation of other food items in the weanling diet, particularly honey, a confirmed source of C. botulinum, represents yet another retrospective data source to help understand the epidemiological profile of cribra orbitalia in this population. Comparative data from other Egyptian populations, though limited, show similar patterns, however, they display a lower prevalence than the data from Dakhleh.

Adolescent↗

Site-specific reciprocal translocation, t(11;22) (q23;q11), in several unrelated families with 3:1 meiotic disjunction.

We have studied 32 unrelated families with a site-specific reciprocal translocation between chromosomes 11 and 22 [t(11;22) (q23;q11)]. In translocation heterozygotes 3:1 meiotic segregation occurs and results in abnormal progeny who carry the der(22) as a supernumerary chromosome. Phenotypic findings consistent with 47,XX (or XY), +der(22), t(11;22) include mental retardation, preauricular skin tag and/or sinus, ear anomaly, palate anomaly, micrognathia, congenital heart disease, and genital anomalies in males. The frequency of abortions among offspring of male and female heterozygotes is increased. Segregation analysis shows that the risk of unbalanced offspring to be born to female heterozygotes may be as high as 10%, and that there may be a significant risk to male heterozygotes as well. The overall carrier frequency among progeny of 11;22 translocation carriers is 70.6%. The occurrence of multiple 11;22 translocation events is supported by de novo occurrence of translocation, familial heteromorphic variants of the der(22), and varied racial and ethnic backgrounds of the families. To our knowledge, with the exclusion of centric fusion translocations, this represents the only example of nonrandom exchange in a constitutional chromosomal rearrangement.

Abnormalities, Multiple↗

Complex karyotypic mosaicism as a result of non-disjunction and subsequent centromere fission.

Karyotypic discrepancy among four different cell types is described in tissues derived from a pregnancy terminated because of chromosomal anomalies. Chorionic villus cells demonstrated 46,XX (direct preparation) and 46,XX/47,XX,+mar1 (cultured cells) karyotypes, while fetal skin fibroblasts had a karyotype of 47,XX,+18 and the placenta showed a triple mosaicism of 47,XX,+18/47,XX,+mar1/48,XX,+18,+mar2. The origin of this complex chromosomal distribution and its significance are discussed in comparison with findings in similar cases.

Abortion, Induced↗