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PubMed1987

Water Relations in Pulvini from Samanea saman: II. Effects of Excision of Motor Tissues.

Pulvinar motor tissues of Samanea saman are often excised for in vitro studies of ion transport. Because ion transport may be regulated in part by hydrostatic pressure (P), this study explores how P and water potential (Psi) change when motor tissues are excised. Water potential (Psi) of excised extensor and flexor tissues was measured by the Chardakov method and compared with Psi measurements made on extensor and flexor tissues of intact pulvini (HL Gorton 1987 Plant Physiol 83: 945-950). Psi values for excised extensor and flexor tissues were always substantially more negative than for the same tissues in intact pulvini. Extensor tissues excised from open pulvini had slightly more negative Psi than excised flexor tissues, and the opposite was true for closed pulvini. Extensor and flexor tissues elongate immediately when excised from open or closed pulvini, suggesting that in intact pulvini they are constrained from elongating by the nonextensible vascular core. In addition, both tissues in both open and closed pulvini are under compression imposed by oppositely positioned motor tissue. Excision relieves constraint and compression, decreasing P, and thus decreasing Psi. This finding may explain, at least in part, the difference between Psi measurements on intact and excised motor tissues. Implications of these data for the planning and interpretation of in vitro experiments requiring excised strips of extensor and flexor tissues are discussed.

Journal Article↗

PubMed2001

Somatic and germinal excision activities of the Arabidopsis transposon Tag1 are controlled by distinct regulatory sequences within Tag1.

Various sequences within Tag1, the endogenous transposon of Arabidopsis, were examined to determine how Tag1 excision and expression are regulated. The 5' intron for the major 2.3-kb Tag1 transcript was found to be critical for the accumulation of Tag1 transcripts and for high rates of somatic excision. This was true for the autonomous element in cauliflower mosaic virus 35S-Tag1-beta-glucuronidase constructs and for a two-component system using the 35S promoter to produce Tag1 transposase and a beta-glucuronidase::dTag1 marker construct to score for excision. The 3' introns of Tag1, although not needed for high transposase expression in primary transgenic plants, were important for maintaining high levels of somatic excision and accumulation of the major but not the minor Tag1 transcripts in subsequent generations. With both 5' and 3' introns present, exchanging the 5' promoter region of Tag1 with the 35S promoter did not affect the timing of Tag1 excision significantly, but it did disrupt germinal excision. Removal of the 5' intron did not abolish germinal excision activity, however. These results indicate that somatic and germinal excision of Tag1 are differentially controlled, with the 5' promoter region being critical for germinal excision activity and the 5' intron playing an important role for somatic excision, possibly via intron-mediated enhancement.

Arabidopsis↗

PubMed1992

Re-excisions of scar in primary cutaneous melanoma: a histopathological study.

In many centres the wide excision and split-skin grafting remains the standard therapy for primary cutaneous melanoma. One-hundred and thirty-seven primary cutaneous melanomas were seen in our department during a 3-year period; 25 patients were subsequently subjected to re-excision of scar following the initial excision biopsy. Lymphatic permeation, field change in the epidermal melanocytes and micrometastases were sought in the re-excision specimens in order to examine the pathological basis for this therapy. Two of the 25 primary melanomas included in this study were known to have been incompletely excised at the time of initial biopsy and both re-excision specimens included a few nests of atypical melanocytes adjacent to one edge of the biopsy wound. Examination of the re-excision specimens failed to demonstrate evidence of direct lymphatic permeation by melanoma, or of a field change in the epidermal melanocytes adjacent to the melanomas, although five specimens from sun-exposed sites showed slight melanocyte atypia. One re-excision specimen did include a single small group of melanocytes, less than 120 microns in size, in the dermis within 2 mm of the initial excision biopsy site of a melanoma 8.4 mm in thickness. These results support the view that more extensive local therapy than complete excision of primary cutaneous melanoma with a narrow margin of adjacent normal skin, is unlikely to benefit the patient.

Cicatrix↗

PubMed1999

Novel organization of genes involved in prophage excision identified in the temperate lactococcal bacteriophage TP901-1.

In this work, the phage-encoded proteins involved in site-specific excision of the prophage genome of the temperate lactococcal bacteriophage TP901-1 were identified. The phage integrase is required for the process, and a low but significant frequency of excision is observed when the integrase is the only phage protein present. However, 100% excision is observed when the phage protein Orf7 is provided as well as the integrase. Thus, Orf7 is the TP901-1 excisionase, and it is the first excisionase identified that is used during excisive recombination catalyzed by an integrase belonging to the family of extended resolvases. Orf7 is a basic protein of 64 amino acids, and the corresponding gene (orf7) is the third gene in the early lytic operon. This location of an excisionase gene of a temperate bacteriophage has never been described before. The experiments are based on in vivo excision of specifically designed excision vectors carrying the TP901-1 attP site which are integrated into attB on the chromosome of Lactococcus lactis. Excision of the vectors was investigated in the presence of different TP901-1 genes. In order to detect very low frequencies of excision, a method for positive selection of loss of genetic material based upon the upp gene (encoding uracil phosphoribosyltransferase) was designed, since upp mutants are resistant to fluorouracil. By using this system, frequencies of excision on the order of 10(-5) per cell could easily be measured. The described selection principle may be of general use for many organisms and also for types of deletion events other than excision.

Bacteriophages↗

PubMed2002

Nucleoside analog resistance caused by insertions in the fingers of human immunodeficiency virus type 1 reverse transcriptase involves ATP-mediated excision.

Although anti-human immunodeficiency virus type 1 (HIV-1) therapy has prolonged the lives of patients, drug resistance is a significant problem. Of particular concern are mutations that cause cross-resistance to a particular class of drugs. Among the mutations that cause resistance to several nucleoside analogs are the insertion of amino acids in the fingers subdomain of HIV-1 reverse transcriptase (RT) at positions 69 and 70. These insertions are usually associated with changes in the flanking amino acids and with a change to F or Y at position 215. We have proposed that the T215F/Y mutation makes the binding of ATP to HIV-1 RT more effective, which increases the excision of 3-azido-3'-deoxythymidine-5'-monophosphate (AZTMP) in vitro and increases zidovudine (AZT) resistance in vivo. Although the mechanism of AZT resistance involves enhanced excision, resistance to 3TC involves a block to incorporation of the analog. We measured the effects of fingers insertion mutations on the misincorporation and excision of several nucleoside analogs. RT variants with the amino acid insertions in the fingers and T215Y have a decreased level of misincorporation of ddATP and 3TCTP. These mutants also have the ability to excise AZTMP by ATP-dependent pyrophosphorylysis. However, unlike the classic AZT resistance mutations (M41L/D67N/K70R/T215Y or F/K219E or Q), the combination of the amino acid insertions in the fingers and the T215Y mutation allows efficient excision of ddTMP and d4TMP, even when relatively high levels of deoxynucleoside triphosphates are present in the reaction. Although the dideoxynucleoside analogs of other nucleosides were excised more slowly than AZTMP, ddTMP, and d4TMP, the mutants with the fingers insertion and T215Y excised all of the nucleoside analogs that were tested more efficiently than wild-type RT or a mutant RT carrying the classical AZT resistance mutations. In the ternary complex (RT/template-primer/dNTP), the presence of the bound dNTP prevents the end of the primer from gaining access to the nucleotide binding site (N site) where excision occurs. Gel shift analysis showed that the amino acid insertions in the fingers destabilized the ternary complex compared to wild-type HIV-1 RT. If the ternary complex is unstable, the end of the primer can gain access to the N site and excision can occur. This could explain the enhanced excision of the nucleoside analogs.

Adenosine Triphosphate↗

PubMed1998

Extensive, nonrandom diversity of excision footprints generated by Ds-like transposon Ascot-1 suggests new parallels with V(D)J recombination.

Upon insertion, transposable elements can disrupt or alter gene function in various ways. Transposons moving through a cut-and-paste mechanism are in addition often mutagenic when excising because repair of the empty site seldom restores the original sequence. The characterization of numerous excision events in many eukaryotes indicates that transposon excision from a given site can generate a high degree of DNA sequence and phenotypic variation. Whether such variation is generated randomly remains largely to be determined. To this end, we have exploited a well-characterized system of genetic instability in the fungus Ascobolus immersus to perform an extensive study of excision events. We show that this system, which produces many phenotypically and genetically distinct derivatives, results from the excision of a novel Ds-like transposon, Ascot-1, from the spore color gene b2. A unique set of 48 molecularly distinct excision products were readily identified from a representative sample of excision derivatives. Products varied in their frequency of occurrence over 4 orders of magnitude, yet most showed small palindromic nucleotide additions. Based on these and other observations, compelling evidence was obtained for intermediate hairpin formation during the excision reaction and for strong biases in the subsequent processing steps at the empty site. Factors likely to be involved in these biases suggest new parallels between the excision reaction performed by transposons of the hAT family and V(D)J recombination. An evaluation of the contribution of small palindromic nucleotide additions produced by transposon excision to the spectrum of spontaneous mutations is also presented.

Ascomycota↗

PubMed2004

Small margin excision of periocular basal cell carcinoma: 5 year results.

BACKGROUND: The traditional surgical management of nodular adnexal basal cell carcinomas (BCC) involves excision with 3-4 mm margins and primary repair. This may remove a significant area of healthy tissue, often necessitating a complicated reconstruction, without the confirmation that tumour excision is complete. METHODS: Nodular adnexal BCCs were excised with 2 mm margins, and the repair delayed for 2 days, providing time for histological confirmation of complete excision with formal paraffin sections. Any incompletely excised tumours underwent further resection, which was facilitated by the undisturbed wound edges. Repair was again delayed until further histological examination had confirmed complete excision. RESULTS: 5 year follow up data were available for 55 patients who had undergone small margin BCC excision with delayed repair. 10 patients required more than one excision to achieve clear margins. There were no recurrences. CONCLUSION: Small margin excision of nodular adnexal BCCs with delayed repair is a safe and efficient method. Delayed repair allows histological confirmation of complete excision and assists further resection if required. Preservation of healthy tissue is maximised allowing less radical reconstructive surgery without resorting to Mohs' labour intensive technique.

Adult↗

PubMed2001

Evaluation of simultaneous excision of pancreatic cancer and the surrounding blood vessels.

Of the 139 patients who underwent excision for invasive cancer in the pancreatic duct at Kurume University Hospital between January 1965 and December 1998, the subjects were 38 patients in whom blood vessels around the cancer were simultaneously excised. The surgical methods were pancreatoduodenectomy (PD) in 31 patients, distal pancreatectomy (DP) in 5, and total pancreatectomy (TP) in 2. The excised blood vessels were the portal vein alone in 32 patients, the artery alone in 1, and both portal vein and artery in 5. Excision of the portal vein was performed by circumcision in 25 patients and by segmentectomy in 12. The range of circumcision was 1.0-7.0 cm (mean, 3.5 +/- 1.4 cm), and the blocking time of the portal vein was 8-36 min (mean, 19.5 +/- 8.8 min). Of the 25 patients who underwent circumcision, reconstruction was performed by end-to-end anastomosis in 23 and by transplantation of the autologous vein between the ends in 2. Of the 12 patients who underwent segmentectomy, direct suture was performed in 10, and transplantation of an autologous vein patch was performed in 2. Postoperative complications occurred in 14 of the 32 patients. In 5 of the 6 patients who underwent excision of the artery, reconstruction was performed by end-to-end anastomosis in 3 and by transplantation of the autologous vein between the ends in 2. Postoperative complications did not occur in the patient who had undergone excision of the artery alone, but 4 of the 5 patients who had undergone simultaneous excision of the portal vein and artery had postoperative complications, of whom 2 died during the period of hospitalization. Three patients with pv0, pv1 or pv2 survived for more than 3 years. Because some of the patients who had undergone excision of the portal vein alone survived for a long time and this method is relatively safe, this surgery can be generally applied, but simultaneous excision of the portal vein and artery should be carefully applied because the incidences of postoperative complications and death during the period of hospitalization are high. With the development of surgical techniques and postoperative control, simultaneous excision of pancreatic cancer and the surrounding blood vessels has become safe, but this method should only be applied to patients who have the potential to recover completely.

Hepatic Artery↗

PubMedDate not supplied

Secondary excision of choledochal cysts after previous cyst-enterostomies.

BACKGROUND/AIMS: Patients with a choledochal cyst previously treated by internal drainage should undergo secondary cyst excision. The results of such secondary excisions have not yet been reported. METHODOLOGY: Over a 27-year period, 121 patients underwent excision of a choledochal cyst at our hospitals. Of these, 14 patients underwent secondary cyst excision following internal drainage. These patients were compared retrospectively with the remaining 107 patients who underwent primary cyst excision. RESULTS: Blood loss and operative time were greater, and early and late post-operative complications were significantly more frequent in the secondary excision group. Wound infection (early complication), pancreatic stones (late complication), and hepatolithiasis (late complication) were significantly more common in the secondary excision group. Histologically, inflammation and biliary glands were more frequently seen in the resected bile ducts in the secondary excision group. CONCLUSIONS: The long-term results of secondary excision of choledochal cysts are worse than after primary excision. The frequent late complications may be related to the development of biliary glands as a consequence of cyst-enterostomy.

Adolescent↗

PubMed2000

Risk factors for cervical stenosis after loop electrocautery excision procedure.

OBJECTIVE: To assess frequency of and identify risk factors for the development of cervical stenosis after loop electrosurgical excision procedure. METHODS: We reviewed outpatient charts of women treated by loop excision for cervical dysplasia between August 1996 and January 1998 in the colposcopy clinic at Massachusetts General Hospital. One hundred sixty-four women were evaluated for cervical stenosis during follow-up. Stenosis was considered present if manual dilation was required to allow endocervical sampling with an endocervical currette 3 mm wide. Multivariable analysis with stepwise logistic regression was used to evaluate age, parity, tobacco use, hormonal status, use of oral contraceptives, pathology, previous loop excision, performance of additional endocervical excision, and dimensions of excision specimens as predictors of cervical stenosis. RESULTS: The average age was 32 years. Cervical stenosis occurred in ten of 164 women (6%, 95% CI 3%, 11%). Among factors analyzed, previous loop excision and volume of excision specimen were the only independent predictors of stenosis. CONCLUSION: Cervical stenosis correlated with history of loop excision and volume of tissue removed, suggesting that women who have second excisions or large excisions should be counseled that their risk of stenosis might be higher.

Adolescent↗

PubMed2003

Optimal excision margins for primary cutaneous melanoma: a systematic review and meta-analysis.

OBJECTIVE: To determine in patients with localized primary melanoma of the trunk or extremities the optimal excision margin that achieves the highest disease-free survival and overall survival and the lowest local recurrence rate. DATA SOURCES: Trials comparing 2 different excision margins were identified by searching MEDLINE from 1966 to May 2002 using the term "melanoma," subheading "surgery," and limiting the search to human studies and randomized controlled trials (RCTs). Additional studies were found using the MeSH term "surgical procedures, operative," combining with "melanoma," and limiting to human studies. We searched EMBASE and the Cochrane Library in May 2002 using similar terminology. No language restriction was applied. STUDY SELECTION: We selected studies for the overview using the following inclusion criteria: design--an RCT with wide excision versus narrower excision (margin width was not specified a priori); population--adult patients (> 18 yr) with cutaneous melanoma of the trunk or extremities without evidence of metastasis; intervention--surgical excision of the primary melanoma; and outcomes--at least 1 of overall survival, disease-free survival, local recurrence, wound complications and necessity for skin grafting. DATA EXTRACTION: Information was abstracted for each outcome reported in the studies, and results were pooled by consensus. Statistical analysis was performed using RevMan 4.1 (The Cochrane Collaboration) software program. Relative risk and risk difference were reported with 95% confidence intervals. The number needed to harm was calculated for the need for skin grafting by taking the inverse of the risk difference. DATA SYNTHESIS: Three trials and their follow-up studies met the inclusion criteria and included 2087 adults with localized cutaneous melanoma of the trunk or extremities. No statistically significant differences were found between wide surgical excision (margins ranging from 3-5 cm) and narrower surgical excision (margins ranging from 1-2 cm) with respect to mortality, disease-free survival or local recurrence rate. CONCLUSIONS: Surgical excision margins no more than 2 cm around a melanoma of the trunk or extremities are adequate; overall survival, disease-free survival and recurrence rate are not adversely affected compared with a wider excision. There is more data to support a 2-cm margin than a 1-cm margin as the minimum margin of excision. Surgical margins should be no less than 1 cm around the primary melanoma.

Biopsy↗

PubMed2004

Comparison of completely versus incompletely excised cutaneous squamous cell carcinomas.

INTRODUCTION: This is a retrospective case series of cutaneous squamous cell carcinomas (SCCs) which were incompletely excised in National Skin Centre, Singapore from 1991 to 1995. This study compared the characteristics of completely excised versus incompletely excised cutaneous SCCs. MATERIALS AND METHODS: All patients with histologically confirmed SCCs were traced from computerised medical database and information regarding patient profile, tumour characteristics, surgical treatment and outcome were collated. All patients were recalled for clinical examination and documentation of cure. Completely excised and incompletely excised SCCs were compared with regards to the patient and tumour characteristics. RESULTS: There were 57 patients with 63 SCCs who were treated with surgical excision over the 5-year period. Fifty were recalled for physical examination. There were 30 males and 27 females and their mean age was 83.3 years. All except 1 were Chinese of Fitzpatrick skin type 4. One-third of patients had daily or weekly sun exposure in the past and 21.1% had occupational sun exposure; 3.5% had prior arsenic exposure and 3.5% were previously treated with radiotherapy for other malignancies. The mean duration of SCCs was 18.7 months; 7.9% of patients had multiple SCCs and 15.9% had underlying actinic keratoses. The mean diameter of the tumours was 1.97 cm and nearly half were located on the head and neck. All the SCCs were primary and localised to the skin; 84.1% of them were completely excised with a 4 to 6 mm margin. Incompletely excised SCCs were associated with the male sex, larger tumours and tumours on the genitals and lower limbs. CONCLUSION: In our experience, the tumour clearance rate is 84.1% following conventional excision. Incomplete excision is associated with male sex, larger tumours and those on the genitals and lower limbs.

Aged↗

PubMed1996

Surgical excision of large rectal villous adenomas.

Large villous tumors occur most frequently in the rectosigmoid and have a significant incidence of harboring a malignancy. The presence or absence of malignancy may be determined only by complete excision. Presence of invasive carcinoma on pathologic examination requires surgical intervention appropriate for that diagnosis. Recurrence depends on the technique used for tumor removal. It is highest for fulguration and local excision and lowest for operations that excise all or part of the rectum. Because most recurrences can be managed with local measures and the risk of malignancy in recurrences is relatively low, the procedure with which the tumor can be completely excised with the least morbidity should be used. Local excision with or without mucosal closure should be used as first-line surgical therapy whenever possible. It should be possible to manage most tumors in the mid and low rectum with this technique. For larger tumors and those tumors more proximal, it may be necessary to use snare cautery in combination with local excision or fulguration. Alternately, for some proximal rectal lesions the two-scope technique mentioned earlier may allow local excision. For circumferential or near circumferential tumors in the low to mid rectum, circumferential mucosectomy should be used. It has been used successfully for tumors involving the entire rectum down to the dentate line. Although this technique has a low recurrence rate, the rate of incontinence associated with it precludes its use in smaller tumors that are amenable to local excision. Transanal endoscopic microsurgery described by Beuss et al can produce good results. The authors have no experience with this technique. However, because of its expense, the need for specialized training, and the infrequency with which other transanal techniques are insufficient, we fail to see a significant role for its use. If use of this technique becomes more widespread, additional data regarding its value will become available. Posterior approaches offer no advantage for removal of tumors that can be excised by transanal techniques. Most tumors that require partial or complete rectal excision should be amenable to anterior or low anterior resection. Low anterior resection is a less morbid procedure with which most surgeons have a fairly extensive experience. For extremely large tumors that extend to the dentate line, coloanal anastomosis is appropriate. The functional results are acceptable compared with the alternative of abdominoperineal resection. Abdominoperineal resection should be reserved for those patients with a diagnosis of invasive carcinoma in whom a lesser procedure would not constitute adequate treatment.

Adenoma, Villous↗

PubMedDate not supplied

Nasal base narrowing: the combined alar base excision technique.

OBJECTIVE: To evaluate the role of the combined alar base excision technique in narrowing the nasal base and correcting excessive alar flare. METHODS: The study included 60 cases presenting with a wide nasal base and excessive alar flaring. The surgical procedure combined an external alar wedge resection with an internal vestibular floor excision. All cases were followed up for a mean of 32 (range, 12-144) months. Nasal tip modification and correction of any preexisting caudal septal deformities were always completed before the nasal base narrowing. RESULTS: The mean width of the external alar wedge excised was 7.2 (range, 4-11) mm, whereas the mean width of the sill excision was 3.1 (range, 2-7) mm. Completing the internal excision first resulted in a more conservative external resection, thus avoiding any blunting of the alar-facial crease. No cases of postoperative bleeding, infection, or keloid formation were encountered, and the external alar wedge excision healed with an inconspicuous scar that was well hidden in the depth of the alar-facial crease. Finally, the risk of notching of the alar rim, which can occur at the junction of the external and internal excisions, was significantly reduced by adopting a 2-layered closure of the vestibular floor (P = .01). CONCLUSIONS: The combined alar base excision resulted in effective narrowing of the nasal base with elimination of excessive alar flare. Commonly feared complications, such as blunting of the alar-facial crease or notching of the alar rim, were avoided by using simple modifications in the technique of excision and closure.

Esthetics↗

PubMed1992

Breast cancer. Importance of adequate surgical excision prior to radiotherapy in the local control of breast cancer in patients treated conservatively.

The extent of excision performed for mammary carcinoma prior to radiotherapy as a risk factor for local recurrence was studied in 503 patients. Three hundred twenty-three tumors (62%) were excised with a minimal rim of tissue (tumorectomy). One hundred forty-two patients (27%) had wide excision and 56 (11%) had quadrantectomy. Tumor stage, size, and radiation treatment were similar for all groups. Forty-one percent of tumorectomies had involved margins, and only 14% and 7% were involved in the wide excision and quadrantectomy groups, respectively. Local failure was 15% for tumorectomy, 7% for wide excision, and 5% for quadrantectomy. In T1 ductal carcinoma, only 4% of those with excisions greater than 5 cm had recurrences. Lesser excision had 20% recurrence. Extent of excision before radiotherapy is an important risk factor for recurrence. Failure was inversely proportional to the amount of breast tissue resected. Narrow excision should be discouraged since a larger tumor burden remains that may not be sterilized by radiation.

Adult↗

PubMed2006

Testing excision models for responses of mismatch-repair systems to UV photoproducts in DNA.

Mismatch-repair (MMR) systems correct DNA replication errors and respond to a variety of DNA lesions. Previous observations that MMR antagonizes UV mutagenesis, and that the mismatch-recognition protein heterodimer MSH2*MSH6 (MutSalpha) selectively binds DNA containing "mismatched" photoproducts (T[CPD]T/AG, T[6-4]T/AG) but not "matched" photoproducts (T[CPD]T/AA, T[6-4]T/AA), suggested that mismatched photoproducts would provoke MMR excision similar to mismatched bases. Excision of incorrect nucleotides inserted opposite template photoproducts might then prevent UV-induced mutation. We tested T[CPD]T/AG DNA, in a sequence context in which it is bound substantially by hMutSalpha and in three other contexts, for stimulation of 3' MMR excision in mammalian nuclear extracts. T[CPD]T/AG was inactive in HeLa extracts, or in extracts deficient in the photoproduct-binding proteins DDB or XPC* hHR23B, arguing against interference from the nucleotide excision repair pathway. Prior incubation with hMutSalpha and MLH2.PMS2 (hMutLalpha) did not increase excision relative to homoduplex controls. T[6-4]T/AG also failed to provoke excision. T/G, C/A, and T/T substrates, even though bound by hMutSalpha no better than T[CPD]T/AG substrates, efficiently provoked excision. Even a substrate containing three T[CPD]T/AG photoproducts (in different contexts) did not significantly provoke excision. Thus, MMR may suppress UV mutagenesis by non-excisive mechanisms.

Animals↗

PubMed2004

Excision of Sleeping Beauty transposons: parameters and applications to gene therapy.

A major problem in gene therapy is the determination of the rates at which gene transfer has occurred. Our work has focused on applications of the Sleeping Beauty (SB) transposon system as a non-viral vector for gene therapy. Excision of a transposon from a donor molecule and its integration into a cellular chromosome are catalyzed by SB transposase. In this study, we used a plasmid-based excision assay to study the excision step of transposition. We used the excision assay to evaluate the importance of various sequences that border the sites of excision inside and outside the transposon in order to determine the most active sequences for transposition from a donor plasmid. These findings together with our previous results in transposase binding to the terminal repeats suggest that the sequences in the transposon-junction of SB are involved in steps subsequent to DNA binding but before excision, and that they may have a role in transposase-transposon interaction. We found that SB transposons leave characteristically different footprints at excision sites in different cell types, suggesting that alternative repair machineries operate in concert with transposition. Most importantly, we found that the rates of excision correlate with the rates of transposition. We used this finding to assess transposition in livers of mice that were injected with the SB transposon and transposase. The excision assay appears to be a relatively quick and easy method to optimize protocols for delivery of genes in SB transposons to mammalian chromosomes in living animals.

Animals↗

PubMed2005

Is local excision of T2/T3 rectal cancers adequate?

In selected patients, local excision of rectal cancer may be an alternative to radical surgery such as abdominoperineal excision of the rectum or anterior resection. Local excision carries lower mortality and morbidity, without the functional disturbance or alteration in body image that can be associated with radical surgery. There are several techniques of local therapy for rectal cancer, with most experience being available in transanal excision. Transanal endoscopic microsurgery is also used but experience with this newer technique is limited. Patient selection is the most important factor in successful local excision; however, specific criteria for selecting patients have not been universally accepted. Review of the published literature is difficult because of the variation in adjuvant therapy regimes and follow-up strategies, as well as results reported in terms of local recurrence and survival rates. There is increasing evidence to suggest that local excision should be restricted to patients with T1-stage rectal cancer without high-risk factors. The place for local excision in patients with T2 or high-risk T1 tumours requires prospective, randomised multicentre trials comparing radical surgery with local excision, with or without adjuvant therapy. Local excision for T3 tumours should be restricted to the palliative setting or patients unfit for radical surgery.

Colorectal Neoplasms↗