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PubMed1988

Allelic and ectopic recombination between Ty elements in yeast.

Allelic and nonallelic (ectopic) recombination events were analyzed in a set of isogenic strains that carry marked Ty elements. We found that allelic recombination between Ty elements occurred at normal frequencies both in meiosis and mitosis. The marked Ty elements were involved in a large variety of different types of ectopic recombination and this variety was greater in mitosis than in meiosis. Allelic and ectopic recombination events occurred at similar frequencies in mitosis, but allelic recombination predominated in meiosis. Some of the types of ectopic mitotic recombination indicated the common occurrence of concerted recombination events. The length of homology represented by a delta element (330 bp) seemed to be sufficient for some types of mitotic and meiotic recombination.

Alleles↗
PubMed1990

A defect in mismatch repair in Saccharomyces cerevisiae stimulates ectopic recombination between homeologous genes by an excision repair dependent process.

Null mutations in three recombination and DNA repair genes were studied to determine their effects on mitotic recombination between the duplicate AdoMet (S-adenosylmethionine) synthetase genes (SAM1 and SAM2) in Saccharomyces cerevisiae. SAM1 and SAM2, located on chromosomes XII and IV, respectively, encode functionally equivalent although differentially regulated AdoMet synthetases. These similar but not identical (homeologous) genes are 83% homologous at the nucleotide level and this identity is limited solely to the coding regions of the genes. Single frameshift mutations were introduced into the 5' end of SAM1 and the 3' end of SAM2 by restriction site ablation. The sequences surrounding these mutations differ significantly in their degree of homology to the corresponding area of the other gene. Mitotic ectopic recombination between the mutant sam genes occurs at a rate of 8.4 x 10(-9) in a wild-type genetic background. Gene conversion of the marker within the region of greater sequence homology occurs 20-fold more frequently than conversion of the marker within the region of relative sequence diversity. The relative orientation of the two genes prevents the recovery of translocations. Mitotic recombination between the sam genes is completely dependent on the DNA repair and recombination gene RAD52. A mutation in PMS1, a mismatch repair gene, causes a 4.5-fold increase in the rate of ectopic recombination. RAD1, an excision repair gene, is required to observe this increased rate of ectopic conversion. In addition, RAD1 is involved in modulating the pattern of coconversion during recombination between the homeologous sam genes. These results suggest that interactions between mismatch repair, excision repair and recombinational repair functions are involved in determining the ectopic gene conversion frequency between the sam genes.

Base Sequence↗
PubMed1991

Chromosome rearrangement by ectopic recombination in Drosophila melanogaster: genome structure and evolution.

Ectopic recombination between interspersed repeat sequences generates chromosomal rearrangements that have a major impact on genome structure. A survey of ectopic recombination in the region flanking the white locus of Drosophila melanogaster identified 25 transposon-mediated rearrangements from four parallel experiments. Eighteen of the 25 were generated from females carrying X chromosomes heterozygous for interspersed repeat sequences. The cytogenetic and molecular analyses of the rearrangements and the parental chromosomes show: (1) interchromosomal and intrachromosomal recombinants are generated in about equal numbers; (2) ectopic recombination appears to be a meiotic process that is stimulated by the interchromosomal effect to about the same degree as regular crossing over; (3) copies of the retrotransposon roo were involved in all of the interchromosomal exchanges; some copies were involved much more frequently than others in the target region; (4) homozygosis for interspersed repeat sequences and other sequence variations significantly reduced ectopic recombination.

Animals↗
PubMed1997

The maize transposable element Ac induces recombination between the donor site and an homologous ectopic sequence.

The prominent repair mechanism of DNA double-strand breaks formed upon excision of the maize Ac transposable element is via nonhomologous end joining. In this work we have studied the role of homologous recombination as an additional repair pathway. To this end, we developed an assay whereby beta-Glucuronidase (GUS) activity is restored upon recombination between two homologous ectopic (nonallelic) sequences in transgenic tobacco plants. One of the recombination partners carried a deletion at the 5' end of GUS and an Ac or a Ds element inserted at the deletion site. The other partner carried an intact 5' end of the GUS open reading frame and had a deletion at the 3' end of the gene. Based on GUS reactivation data, we found that the excision of Ac induced recombination between ectopic sequences by at least two orders of magnitude. Recombination events, visualized by blue staining, were detected in seedlings, in pollen and in protoplasts. DNA fragments corresponding to recombination events were recovered exclusively in crosses with Ac-carrying plants, providing physical evidence for Ac-induced ectopic recombination. The occurrence of ectopic recombination following double-strand breaks is a potentially important factor in plant genome evolution.

Base Sequence↗
PubMed1999

Double-strand break-induced recombination between ectopic homologous sequences in somatic plant cells.

Homologous recombination between ectopic sites is rare in higher eukaryotes. To test whether double-strand breaks (DSBs) can induce ectopic recombination, transgenic tobacco plants harboring two unlinked, nonfunctional homologous parts of a kanamycin resistance gene were produced. To induce homologous recombination between the recipient locus (containing an I-SceI site within homologous sequences) and the donor locus, the rare cutting restriction enzyme I-SceI was transiently expressed via Agrobacterium in these plants. Whereas without I-SceI expression no recombination events were detectable, four independent recombinants could be isolated after transient I-SceI expression, corresponding to approximately one event in 10(5) transformations. After regeneration, the F1 generation of all recombinants showed Mendelian segregation of kanamycin resistance. Molecular analysis of the recombinants revealed that the resistance gene was indeed restored via homologous recombination. Three different kinds of reaction products could be identified. In one recombinant a classical gene conversion without exchange of flanking markers occurred. In the three other cases homologous sequences were transferred only to one end of the break. Whereas in three cases the ectopic donor sequence remained unchanged, in one case rearrangements were found in recipient and donor loci. Thus, ectopic homologous recombination, which seems to be a minor repair pathway for DSBs in plants, is described best by recombination models that postulate independent roles for the break ends during the repair process.

Base Sequence↗
PubMed2001

Distribution of cyclooxygenase-2 in eutopic and ectopic endometrium in endometriosis and adenomyosis.

The objective of this study was to determine the distribution of cyclooxygenase-2 (COX-2) in eutopic and ectopic endometria in endometriosis and adenomyosis. The subjects were 35 patients with endometriosis diagnosed by laparoscopy, 33 patients with histologically confirmed adenomyosis and 50 female controls with normal fecundity. Expression of COX-2 was immunohistochemically investigated in tissues from eutopic endometrium and myometrium and ectopic endometrium of the wall of ovarian chocolate cysts using polyclonal antibody. Surface epithelial cells, endometrial glandular epithelial cells or stromal cells were assessed. Cells were semi-quantitatively assessed on a scale of 1 to 5 using a nomogram created from positive cell count and the degree of staining. COX-2 expression in surface and glandular epithelia of the control group varied markedly during the menstrual cycle. It was lowest in the early proliferative phase and gradually increased thereafter. It remained high throughout the secretory phase. However, in patients with endometriosis, expression of COX-2 in glandular epithelium was higher than that in the control group, though it varied throughout the menstrual cycle. On the other hand, there was no variation in expression of COX-2 in the adenomyosis group during the menstrual cycle, and it was lower than that in the endometriosis group in all phases. Pronounced COX-2 expression was observed in glandular cells from ectopic endometrial tissue of ovarian chocolate cyst walls in all cases regardless of the menstrual phase. In summary, increased COX-2 expression in eutopic and ectopic endometria was believed to be strongly correlated with pathological abnormalities in these disorders.

Adult↗
PubMed2006

Ectopic over-expression of the maize beta-glucosidase Zm-p60.1 perturbs cytokinin homeostasis in transgenic tobacco.

The activity of the phytohormone cytokinin depends on a complex interplay of factors such as its metabolism, transport, stability, and cellular/tissue localization. O-glucosides of zeatin-type cytokinins are postulated to be storage and/or transport forms, and are readily deglucosylated. Transgenic tobacco (Nicotiana tabacum L. cv. Petit Havana SR1) plants were constructed over-expressing Zm-p60.1, a maize beta-glucosidase capable of releasing active cytokinins from O- and N3-glucosides, to analyse its potential to perturb zeatin metabolism in planta. Zm-p60.1 in chloroplasts isolated from transgenic leaves has an apparent K(m) more than 10-fold lower than the purified enzyme in vitro. Adult transgenic plants grown in the absence of exogenous zeatin were morphologically indistinguishable from the wild type although differences in phytohormone levels were observed. When grown on medium containing zeatin, inhibition of root elongation was apparent in all seedlings 14 d after sowing (DAS). Between 14 and 21 DAS, the transgenic seedlings accumulated fresh weight leading later (28-32 DAS) to ectopic growths at the base of the hypocotyl. The development of ectopic structures correlated with the presence of the enzyme as demonstrated by histochemical staining. Cytokinin quantification showed that transgenic seedlings grown on medium containing zeatin accumulate active metabolites like zeatin riboside and zeatin riboside phosphate and this might lead to the observed changes. The presence of the enzyme around the base of the hypocotyl and later, in the ectopic structures themselves, suggests that the development of these structures is due to the perturbance in zeatin metabolism caused by the ectopic presence of Zm-p60.1.

Abscisic Acid↗
PubMed1987

Effects of sympathetic activation on ventricular ectopic beats in subjects with and without evidence of organic heart disease.

In a selected group of 10 apparently healthy subjects and 22 patients with organic heart disease, all with frequent ventricular ectopic beats on Holter monitoring, we assessed the influence of sympathetic activation by comparing the arrhythmogenic effects of a symptom-limited bicycle exercise stress test and 90 degree head up tilt. Tilting reduced ventricular arrhythmias in the normal subjects (-48 +/- 18% from 9 +/- 2 beats min-1, P less than 0.05). Exercise stress testing caused small and insignificant changes in arrhythmias during the early (50-75 W) phases and an almost complete suppression of ventricular ectopic beats in the final stages (-99 +/- 1%, P less than 0.01). In six of the 10 subjects, ventricular arrhythmias reappeared in the early recovery phase. In the 22 patients with organic heart disease, tilting increased ventricular ectopic beats (43 +/- 17% from 9 +/- 3 beats min-1, P less than 0.05); augmented repetitive forms in 12 patients (179 +/- 88% from 1.4 +/- 0.6 per 3 min) and produced repetitive forms in six of the 10 remaining patients who did not show repetitive forms during control conditions. Exercise stress testing caused a marked increase in ectopic activity in the early phase (84 +/- 35%) while the response during the maximal phase of exercise as well as during recovery was related to the effort capabilities. Arrhythmias were increased in 12 patients with limited exercise duration and were reduced in 10 patients with good exercise tolerance. These data indicate that sympathetic activation has different effects on ventricular arrhythmias depending on the clinical setting and that tilting is a useful maneuver to evaluate the arrhythmogenic effects of increased sympathetic activity.

Adult↗
PubMed1992

Immunohistochemical analysis of oestrogen and progesterone receptors of eutopic and ectopic endometrium in the rabbit model of endometriosis: the effect of pregnancy.

Oestrogen receptors (ER) and progesterone receptors (PR) were measured in the rabbit model of endometriosis in eutopic and ectopic endometrium of pregnant animals (n = 7) and controls (n = 7). Immunostaining of cryostat sections of ectopic and eutopic endometrium was performed using monoclonal antibodies against ER and PR. Levels of ER and PR were 'evaluated' in a semi-quantitative manner using a modified histoscore. The ER and PR content in stromal and glandular cells was not different in eutopic and ectopic endometrium in either pregnant or non-pregnant control animals. There was a significant difference between the PR content of the glandular epithelium of pregnant animals and controls for both eutopic (P less than 0.02) and ectopic (P less than 0.001) endometrium. The disappearance of glandular PR and the persistence of stromal PR suggest that the function of the glandular endometrium is mediated by the paracrine and autocrine action of stromal cells. The decidual cells are likely to produce substances that may be of importance in embryo implantation and early pregnancy.

Animals↗
PubMed1988

Ectopic ossification following total hip arthroplasty: is diffuse idiopathic skeletal hyperostosis a risk factor?

Total hip arthroplasty may be followed by ectopic bone formation. An increased frequency has been suspected in patients with diffuse idiopathic skeletal hyperostosis (DISH). In 204 patients we found that, of the 38 subjects with pre-existing DISH, 29% developed postoperative ossification compared with only 10% in those without DISH (p less than 0.01). DISH is therefore a risk factor for postoperative ectopic bone formation. In a separate study of 1325 patients (not analysed for spinal DISH), we looked for correlations between the severity of postoperative ectopic bone and clinical measurements. Even for the more severe ossification grades (n = 112), only 10% reported serious pain and only 26% had reduced hip flexion (less than 70 degrees). Thus, periprosthetic ectopic bone is not sufficiently important to justify the routine use of preventative drugs such as bisphosphonates in patients with DISH undergoing total hip replacement.

Adult↗
PubMed1996

A case of double fingernail and ectopic fingernail.

Congenital ectopic fingernails are extremely rare and only 22 cases were found in domestic and foreign literature during our investigation. In the 22 ectopic fingernail cases collected, small ectopic fingernails were found along side the normal fingernail (dorsal or palm side), in most cases, and extremely rare double nails, which are as large as normal nails, were found on the palm side opposite the normal fingernail in some cases. We encountered a 4-year-old boy with a double fingernail on the right fifth finger and an ectopic fingernail on the left fifth finger. The nail on the palm side, including the fingernail block and nail matrix, was excised from the right fifth finger and the defect was reconstructed with a palm skin flap.

Child, Preschool↗
PubMed2002

Sex differences in rapid auditory processing deficits in ectopic BXSB/MpJ mice.

Prior research with rodent models, performed predominantly in males, has demonstrated a significant association between focal neocortical malformations (e.g. ectopias and microgyria) and rate-specific auditory processing deficits. In the current study and consistent with prior findings, we report that ectopic male BXSB/MpJ mice exhibit impairments in detecting a two-tone oddball stimulus at short but not long inter-stimulus interval durations when compared to non-ectopic male littermates. However, ectopic female littermates showed no rapid auditory processing deficit when compared to non-ectopic females on this same task. Current results add growing support to: (1) an association between focal cortical malformations and impaired auditory processing in males; and (2) the existence of sex differences in the behavioral consequences of focal cortical malformations.

Acoustic Stimulation↗
PubMed2004

Selective activation of ectopic grey matter during motor task.

The role of ectopic grey matter in neuronal migration disorders is still a matter of debate. Using fMRI we studied the activation pattern of ectopic and regular cortical neurons in a female patient with subcortical bilateral laminar heterotopia (double cortex syndrome) performing a simple motor task. We demonstrate a synchronous activation pattern of the motor cortex and the adjacent subcortical ectopic grey matter layer during finger-tapping. We also observed activation in the cerebellum ipsilaterally and in the basal ganglia contralaterally. The present findings are consistent with the hypothesis that ectopic neurons may be functionally integrated in motor circuits during repetitive voluntary movements.

Adult↗
PubMed1999

Ectopic orbital meningioma: a case report and review.

PURPOSE: To describe a well-documented case of ectopic orbital meningioma, to review the literature on the subject, and to recommend treatment. METHODS: Neuroradiologic investigations were suggestive of orbital meningioma. The patient underwent total excision of the mass, which was subsequently examined by light microscopy and immunohistochemistry. RESULTS: The patient was diagnosed with ectopic orbital meningioma which was locally invasive. The tumor was surgically excised, and did not recur during a 42-month follow-up interval. CONCLUSIONS: Ectopic orbital meningiomas are rare tumors that develop from ectopic arachnoid tissue. Although locally invasive, the prognosis is favorable if the tumor is completely removed.

Biomarkers, Tumor↗
PubMed2001

Ectopic parathyroid adenomas located at the carotid bifurcation: the role of preoperative Tc-99m MIBI scintigraphy and the intraoperative gamma probe procedure in surgical treatment planning.

PURPOSE: The prevalence of ectopic parathyroid adenoma (PA) is relatively low, despite some studies in which it has been reported to be as high as 20%. Ectopic PA is a frequent cause of surgical failure, and therefore some authors recommend preoperative imaging to localize the condition in patients with primary hyperparathyroid (HPT) disease before initial surgery. METHODS: Two unusual cases of primary HPT caused by an ectopic PA located at the carotid bifurcation are reported. The patients were examined before operation using Tc-99m MIBI scintigraphy and then underwent radioguided surgery using the intraoperative gamma probe technique with injection of a low dose (37 MBq; 1 mCi) of Tc-99m MIBI. RESULTS: The first patient had a history of primary HPT and coexisting multinodular goiter. She had undergone total thyroidectomy in another center, but no enlarged parathyroid gland was found at bilateral neck exploration and serum calcium and parathyroid hormone levels remained elevated after intervention. The patient was referred to our center. A Tc-99m MIBI scan showed a focus of abnormal tracer uptake in the superior left laterocervical region that was thought to be a PA. The next day she underwent radioguided surgery and an 18-mm PA located at the left carotid bifurcation was easily removed through a 2.5-cm skin incision. The second patient was examined in our center before surgery. A neck ultrasound showed a multinodular goiter but no enlarged parathyroid glands. A pertechnectate-MIBI subtraction scan revealed a focus of abnormal Tc-99m MIBI uptake in the right superior laterocervical region that was thought to be a PA. One week later, at radioguided surgery, a 25-mm PA was identified at the right carotid bifurcation and removed successfully. CONCLUSIONS: These data strongly support the utility of preoperative imaging with Tc-99m MIBI in patients with primary HPT before initial neck exploration with the aim of avoiding surgical failure. Furthermore, the intraoperative gamma probe technique seems to be useful to reduce surgical trauma and, possibly, complications in patients with ectopic PA.

Adenoma↗
PubMed2002

Ectopic ureteroceles in infants with prenatal hydronephrosis: use of renal cortical scintigraphy.

PURPOSE: This study assesses the contribution of renal cortical scintigraphy in the diagnostic evaluation of infants with ectopic ureteroceles. METHODS: The records of 20 infants (age range, 3 weeks to 4 months) who were referred for renal cortical scintigraphy after an ectopic ureterocele associated with a duplex kidney was found during follow-up of prenatal hydronephrosis were reviewed retrospectively. All infants underwent voiding cystourethrography, ultrasonography, and Tc-99m DMSA scintigraphy. RESULTS: All upper moieties showed absent or depressed Tc-99m DMSA uptake. Upper moiety functional impairment was associated with structural abnormalities shown by ultrasonography. The degree of functional impairment was reflective of ultrasonographically defined cortical thickness relative to pelvic diameter, but this relation varied. Eight of 20 (40%) lower moieties had diffusely depressed relative Tc-99m DMSA uptake. Focal defects were also present in three of these eight (38%) lower moieties. Lower moiety functional impairment was associated with higher degrees of pelvic dilatation and with vesicoureteral reflux. Ultrasonography revealed diffuse parenchymal thinning in four of the eight (50%) lower moieties with depressed uptake. Ultrasonography did not define focal parenchymal loss in any lower moiety. CONCLUSIONS: The degree to which function is impaired in the upper moieties of duplex kidneys with ureters terminating in ectopic ureteroceles is not highly predictable by ultrasonography. Lower moiety functional impairment and cortical defects are frequently present in these kidneys and often occur without ultrasonographic evidence of parenchymal damage. Use of renal cortical scintigraphy in the diagnostic evaluation of infants with ectopic ureteroceles is supported.

Female↗
PubMed1989

Histopathologic findings in ectopic tubal pregnancy.

In 141 consecutive cases of tubal ectopic pregnancy at Hermann Hospital in Houston, Texas, the histologic appearance of 129 surgically removed fallopian tubes containing ectopic pregnancies was reviewed and compared with an age- and race-matched control population. There was a higher incidence of chronic salpingitis (88 versus 2%) and salpingitis isthmica nodosa (SIN) (43 versus 5%). The ectopic pregnancy patients had a higher incidence of pelvic inflammatory disease, gonorrhea, previous abortions, bitubal ligation, intrauterine device use, and previous abdominal surgery. In our population, chronic salpingitis was the most commonly associated finding. The increase in SIN was associated with postinflammatory changes (89%). We also found that ectopic tubal pregnancies may grow either intratubally or extratubally by villous invasion into the wall and blood vessels; therefore, surgical salvage of the fallopian tube by extracting the products of conception will not always be curative.

Adolescent↗
PubMed2001

Ectopic bone formation in titanium mesh loaded with bone morphogenetic protein and coated with calcium phosphate.

The osteoinductive properties of porous titanium fiber mesh, with or without a calcium phosphate coating and loaded with recombinant human bone morphogenic protein-2 (rhBMP-2) or rhBMP-2 and native bovine BMP (S-300) were investigated in a rat ectopic assay model. A total of 112 calcium phosphate-coated and 112 noncoated porous titanium implants, either loaded with rhBMP-2 and S-300 or loaded with rhBMP-2 alone, were subcutaneously placed in 56 Wistar-King rats. The rats were killed 5, 10, 20, and 40 days postoperatively, and the implants were retrieved. Histologic analysis demonstrated that all growth factor and carrier combinations induced ectopic cartilage and bone formation at 5 and 10 days, respectively. At 20 days, bone formation increased and was characterized by trabecular bone and bone marrow-like tissue. At 40 days, more lamellar bone and hemopoietic bone marrow-like tissue were present. At both times, more bone had been formed in calcium phosphate-coated implants than in noncoated samples. Further, in rhBMP-2 and S-300-loaded specimens, bone formation was higher than in rhBMP-2 only-loaded specimens. In rhBMP-2 only-loaded specimens, bone formation was mainly localized inside the mesh material, whereas in specimens loaded with both rhBMP-2 and S-300, the bone was localized inside and surrounding the titanium mesh. The histological findings were confirmed by calcium content and alkaline phosphatase activity measurements. In addition, all specimens showed osteocalcin expression as early as 5 days postoperatively. Our results show that the combination of titanium mesh with BMPs can induce ectopic bone formation and that this bone formation seems to be similar to "enchondral" ossification. In addition, a thin calcium phosphate coating can have a beneficial effect on the bone-inducing properties of a scaffold material. Finally, rhBMP-2 and native BMP act synergistically in ectopic bone induction.

Alkaline Phosphatase↗