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At least 811 records · Page 45Linked to original sources

PubMed2000

Mohs micrographic excision of melanoma using immunostains.

BACKGROUND: Mohs excision of melanoma remains controversial, in part because of concerns regarding evaluation of frozen section margins. Several immunohistochemical stains are available for melanoma that can be used on frozen sections. OBJECTIVE: To review our experience with Mohs micrographic excision of melanoma using immunostains. METHODS: Sixty-eight patients were treated, including 46 with melanoma in situ and 22 with invasive melanoma, 62 of which were on the head or neck. HMB-45, MEL-5, Melan-A (A-103), and S-100 stains were employed. RESULTS: Sixty-seven of 68 tumors were excised to clear margins, requiring an average of 2.0 layers. Immunostains greatly enhanced detection of melanoma on frozen sections. The average margin required for clearance of in situ melanoma was 8.3 mm and of invasive melanoma was 11.1 mm. Only 23 of 46 (50%) in situ melanomas were clear with < or =6 mm margins; 15 mm margins were required to clear 96% of the tumors. Eleven of 22 (50%) invasive melanomas were clear with < or =6 mm margins; 26 mm margins were required to clear 95% of the tumors. Melan-A (A-103) was the most consistently crisp and easily interpreted immunostain. CONCLUSIONS: Mohs excision of melanoma using immunostains can be useful, especially for tumors on the head and neck. For routine excision, margins wider than those currently recommended may be required to ensure tumor clearance. We recommend that (1) biopsies be stained preoperatively for Melan-A and/or HMB-45, (2) a debulking layer be obtained for permanent sections prior to Mohs layers, and positive and negative control specimens from the tumor and distant skin should be employed for comparison of staining patterns. Large-scale prospective studies of in situ and invasive melanoma on the head and neck are necessary.

Adult↗

PubMed2001

The efficacy of electrosurgery and excision in treating patients with multiple apocrine hidrocystomas.

BACKGROUND: Apocrine hidrocystomas are adenomatous cystic proliferations of the apocrine glands. They typically occur as solitary lesions, though rarely may occur as multiple lesions. Management of multiple hidrocystomas can be difficult, particularly if they are large. Surgical modalities may be required for effective therapy. OBJECTIVE: To compare the results of electrosurgery and excision in treating multiple apocrine hidrocystomas. METHODS: A 50-year-old man presented with multiple apocrine hidrocystomas ranging in size from 1 to 12 mm. The lesions were located over the periorbital skin, cheeks, and pinnae. Excision and electrodessication were utilized for therapy. At a 1-year follow-up, the patient was evaluated for recurrences and cosmetic result. RESULTS: There were no recurrences until 1 year after surgery. In the areas treated with electrodessication, no visible scars were identified. In the areas treated with excision, localized scars were observed. CONCLUSIONS: Both electrodessiation and excision are effective therapies for multiple apocrine hidrocystomas. We suggest that tumors less than 1 cm be treated with electrodessication and lesions greater than 1 cm with excision.

Adenoma, Sweat Gland↗

PubMed2001

Artificial skin for closure and healing of wounds created by skin cancer excisions.

BACKGROUND: A dermal regeneration template indicated for life-threatening third-degree burn injuries is a product with potential application to smaller wounds to aid in healing and closure of complex excision sites. OBJECTIVE: To assess the effectiveness of dermal regeneration template for closure of skin cancer excision sites that would have otherwise required complicated closures. METHODS: Five patients, 61-84 years old, with skin cancer surgery yielding a total of six wounds were treated with the dermal regeneration template to close and heal their wounds. RESULTS: Four of five patients had complete healing (five of six wounds) with cosmetically acceptable results. The one treatment failure was application of the dermal regeneration template over exposed skull where inadequate neodermis formed. Successful healing was observed in five complex skin cancer excision sites including two wounds in previously irradiated grafted skin, a large and deep temporal defect, a wide excision in the supraclavicular region, and an excision down to cartilage on the antihelix of the ear. No infections were noted, although in four of five patients prophylactic oral antibiotics (either erythromycin or cephalexin) were prescribed postoperatively for 1-2 weeks. CONCLUSION: The product simplified wound care, subjectively appeared to decrease pain and postoperative bleeding, and yielded cosmetically acceptable wound repair. Autografting was not necessary; wounds healed in 2-4 months by epithelialization over neodermis after removal of the silicone layer. Furthermore, the product was a convenient long-term dressing and healing device for wounds where complex repairs, autografts, and/or flaps would otherwise be considered for closure.

Aged↗

PubMed1999

Feasibility of partial A2 and A4 pulley excision: effect on finger flexor tendon biomechanics.

We investigated the effect of partial excision of the A2 and A4 digital pulleys, separately and in combination, on finger angular rotation and the energy for finger flexion. Statistically significant decreases in angular rotation resulted only after 50% and 75% excision of A2, A4, or A2 and A4 in combination. Work of flexion trends were weak and none of the changes were statistically significant. Although optimal finger function relies on the integrity of the A2 and A4 pulleys to maintain the efficiency of the digital flexor system, these data suggest that the A2 and A4 pulleys can be excised up to 25%, either separately or in combination, without significant effects on angular rotation. Decreases in total angular range of motion after 50% and 75% pulley excision were small, even for combined pulley excision (9 degrees +/- 3 degrees and 15 degrees +/- 5 degrees [mean +/- SD], respectively), and may be clinically acceptable.

Biomechanical Phenomena↗

PubMed2003

[Block excision of epithelial ingrowth after cataract surgery--report on 15 patients].

BACKGROUND: Cystic or diffuse epithelial ingrowth into the anterior chamber after cataract surgery is a rare complication. It can lead to painful secondary glaucomas or in case of fistulation to persisting ocular hypotony or atrophy of the globe due to wrong or inadequate therapy. PATIENTS AND METHODS: The cause of epithelial ingrowth was a previous cataract surgery in 15 of 59 patients (25 %, Erlangen Block-Excision Registry for epithelial ingrowth). Eleven patients were females. Mean age was 65 +/- 13 years. RESULTS: Ten patients underwent block excision of epithelium, adjacent iris, ciliary body, sclera or cornea due to epithelial ingrowth following intracapsular cataract extraction between 1980 and 1987 and five patients since 1987 because of epithelial ingrowth following extracapsular cataract extraction (4 with and 1 without intraocular lens implantation); all primary cataract surgeries had been performed in external hospitals. We found a diffuse invasion in 3 eyes (all following icCE) and a cystic epithelial invasion in 12 eyes histologically. Mean time interval between cataract surgery and block excision was 7 +/- 8 years (range: 1 to 33 years). The excisional defect in the globes wall was covered using a tectonic corneoscleral graft (diameter: 8.0 +/- 1.8 mm). Postoperative astigmatism was 3.6 +/- 3.4 dpt. Six eyes had postoperatively a visual acuity of 20/200 or better. No recurrence of epithelial downgrowth was observed, nor was an enucleation needed. CONCLUSION: Surgical procedures with opening of the cyst (e.g. laser) are contraindicated and may lead to a transformation from cystic into diffuse epithelial invasion with potential blindness. The therapy of first choice in eyes with cystic epithelial ingrowth and an extension less than five clock hours is the curative block-excision technique combined with tectonic corneoscleral graft. Surgical results are excellent in order to regard a curative excision and the survival of the eye with acceptable achieved function in consideration of the difficult primary situation with intra- and postoperative complications due to previous cataract surgery.

Aged↗

PubMed2001

Preoperative radiotherapy combined with total mesorectal excision for resectable rectal cancer.

BACKGROUND: Short-term preoperative radiotherapy and total mesorectal excision have each been shown to improve local control of disease in patients with resectable rectal cancer. We conducted a multicenter, randomized trial to determine whether the addition of preoperative radiotherapy increases the benefit of total mesorectal excision. METHODS: We randomly assigned 1861 patients with resectable rectal cancer either to preoperative radiotherapy (5 Gy on each of five days) followed by total mesorectal excision (924 patients) or to total mesorectal excision alone (937 patients). The trial was conducted with the use of standardization and quality-control measures to ensure the consistency of the radiotherapy, surgery, and pathological techniques. RESULTS: Of the 1861 patients randomly assigned to one of the two treatment groups, 1805 were eligible to participate. The overall rate of survival at two years among the eligible patients was 82.0 percent in the group assigned to both radiotherapy and surgery and 81.8 percent in the group assigned to surgery alone (P=0.84). Among the 1748 patients who underwent a macroscopically complete local resection, the rate of local recurrence at two years was 5.3 percent. The rate of local recurrence at two years was 2.4 percent in the radiotherapy-plus-surgery group and 8.2 percent in the surgery-only group (P<0.001). CONCLUSIONS: Short-term preoperative radiotherapy reduces the risk of local recurrence in patients with rectal cancer who undergo a standardized total mesorectal excision.

Adenocarcinoma↗

PubMed2001

Recurrence of dysplasia after loop electrosurgical excision procedures with long-term follow-up.

OBJECTIVE: The aim of this study was to determine the rates of recurrent dysplasia with longer follow-up durations and to determine whether margin status and other variables were associated with recurrence. STUDY DESIGN: A retrospective chart review was performed for all women who underwent a loop electrosurgical excision procedure at Wilford Hall Medical Center, Lackland Air Force Base, Texas, between January 1993 and December 1994. Extracted information included age, parity, indication for the loop electrosurgical excision procedure, histologic classification of the loop electrosurgical excision procedure specimen, margin status, and whether a "deep" (endocervical) pass had been performed. Follow-up data included findings of repeated cytologic examination, colposcopy, and biopsy if performed. RESULTS: The mean duration of follow-up for all women was 24 months. Margins were positive in 28%, with 73% of these being endocervical. The overall recurrent dysplasia rate was 31%, with a mean time to recurrence of 11.9 months. Participants with any positive margins had a higher recurrence rate than did those with negative margins (47% vs 26%; P = .009). High-grade lesions at the margin were more commonly associated with recurrence than were low-grade lesions relative to those with clear margins (high-grade lesion vs negative margins, 55% vs 26%; P = .003; low-grade lesion vs negative margins, 36% vs 26%; P = .34). Recurrence was not associated either with the performance of an endocervical pass or with the histologic diagnosis of the loop electrosurgical excision procedure specimen. CONCLUSION: With comprehensive long-term follow-up, positive margins on loop electrosurgical excision procedure specimens were shown to be a risk factor for recurrence of cervical dysplasia, particularly when high-grade lesions were seen at the margin. Recurrence was also considerable among women with negative margins. Women should be counseled regarding this risk, and the importance of follow-up should be emphasized.

Adolescent↗

PubMed2002

Baseline inaccuracy rates for the comparison of cervical biopsy to loop electrosurgical excision histopathologic diagnoses.

OBJECTIVE: The purpose of this study was to quantify the baseline inaccuracies in histopathologic diagnosis between colposcopically directed cervical biopsies and loop electrosurgical excision procedure specimens. STUDY DESIGN: A retrospective review was made of cervical biopsies and loop electrosurgical excision procedure pairs (n = 448) that were performed at the University of Arizona between 1992 and 2000. Agreement was assessed by kappa statistics and Spearman rho coefficients. Subgroup analysis was performed (n = 139) to assess pairs with significant inaccuracy between biopsy and loop electrosurgical excision procedure, when these were performed within 28 days of each other. RESULTS: Eighty-one percent agreement was found between cervical biopsy and loop electrosurgical excision procedure histopathologic diagnoses, when compared to within 1 degree (kappa, 0.73; P <.0001). A discrepancy that would be attributed to regression or progression was found: mild biopsy (regression, none by definition; progression, 4%), moderate biopsy (regression, 9%; progression, 0%), and severe biopsy (regression, 26%; progression, 0%). CONCLUSION: Even when colposcopically directed cervical biopsy correlates strongly with loop electrosurgical excision procedure histopathologic diagnosis, there is a definable percentage of patients for whom there is a discrepancy between these 2 diagnoses. This discrepancy represents an inherent inaccuracy of the diagnostic testing modality and should not be interpreted as progression or regression of disease.

Biopsy↗

PubMed1984

Escherichia coli DNA photolyase stimulates uvrABC excision nuclease in vitro.

Pyrimidine dimers are the major photoproducts produced in cellular DNA upon UV irradiation. In Escherichia coli there are dark and photorepair mechanisms that eliminate the dimers from DNA and prevent their lethal and mutagenic effects. To determine whether these repair mechanisms act cooperatively or competitively in repairing DNA, we investigated the effects upon one another of DNA photolyase, which mediates photorepair, and uvrABC excision nuclease, an enzyme complex of the uvrABC gene products, which catalyzes nucleotide excision repair. We found that photolyase stimulates the removal of pyrimidine dimers but not other DNA adducts by uvrABC excision nuclease. The two subunits of uvrABC excision nuclease, the uvrA and uvrB proteins which together bind to the dimer region of DNA, had no effect on the activity of photolyase. T4 endonuclease V, which like photolyase is specific for pyrimidine dimers, was inhibited by photolyase, suggesting that these two proteins recognize the same or similar chemical structures in UV-irradiated DNA that are different from those recognized by uvrABC excision nuclease.

Cisplatin↗

PubMed1989

Extent of N-terminal methionine excision from Escherichia coli proteins is governed by the side-chain length of the penultimate amino acid.

In a significant fraction of the Escherichia coli cytosolic proteins, the N-terminal methionine residue incorporated during the translation initiation step is excised. The N-terminal methionine excision is catalyzed by methionyl-aminopeptidase (MAP). Previous studies have suggested that the action of this enzyme could depend mainly on the nature of the second amino acid residue in the polypeptide chain. In this study, to achieve a systematic analysis of the specificity of MAP action, each of the 20 amino acids was introduced at the penultimate position of methionyl-tRNA synthetase of E. coli and the extent of in vivo methionine excision was measured. To facilitate variant protein purification and N-terminal sequence determination, an expression shuttle vector based on protein fusion with beta-galactosidase was used. From our results, methionine excision catalyzed by MAP is shown to obey the following rule: the catalytic efficiency of MAP, and therefore the extent of cleavage, decreases in parallel with the increasing of the maximal side-chain length of the amino acid in the penultimate position. This molecular model accounts for the rate of N-terminal methionine excision in E. coli, as deduced from the analysis of 100 protein N-terminal sequences.

Amino Acid Sequence↗

PubMed1992

Excision repair at individual bases of the Escherichia coli lacI gene: relation to mutation hot spots and transcription coupling activity.

To determine whether base-to-base variations in the rate of excision repair influence the distribution of mutations, we have developed a method to measure UV photoproducts at individual nucleotides in the Escherichia coli chromosome. Specific gene fragments are 3' end-labeled using a sequence-specific oligonucleotide to direct the site of labeling, and photoproducts are identified by enzymatic incision. On the nontranscribed strand of the E. coli lacI gene, the cyclobutane pyrimidine dimer frequency was 2- to 8-fold higher in chromosomal DNA than in a cloned DNA fragment. The chromosomal lesion frequency corresponded to the frequency of UV-induced mutations at mutation hot spots reported in the literature. Only 0-30% of cyclobutane dimers at various sites on this strand were excised in 20 min. In contrast, repair on the transcribed strand was 80-90% complete in 20 min. However, the transcribed strand contained an excision repair "slow spot" at the site of its single mutation hot spot: At this site, no repair occurred for the first 10 min, after which repair proceeded more slowly than typical of that strand. In an mfd strain, deficient in a factor that couples repair to transcription in cell extracts, the excision rate at individual nucleotides on the transcribed strand was minimal at most sites for at least 30 min. Wild-type E. coli's bias for producing mutations at photoproducts on the nontranscribed strand, reported to require the mfd gene, therefore appears to be due to an excision repair system specific for the transcribed strand of chromosomal DNA.

Base Sequence↗

PubMed1997

Interaction of human apurinic endonuclease and DNA polymerase beta in the base excision repair pathway.

Mutagenic abasic (AP) sites are generated directly by DNA-damaging agents or by DNA glycosylases acting in base excision repair. AP sites are corrected via incision by AP endonucleases, removal of deoxyribose 5-phosphate, repair synthesis, and ligation. Mammalian DNA polymerase beta (Polbeta) carries out most base excision repair synthesis and also can excise deoxyribose 5-phosphate after AP endonuclease incision. Yeast two-hybrid analysis now indicates protein-protein contact between Polbeta and human AP endonuclease (Ape protein). In vitro, binding of Ape protein to uncleaved AP sites loads Polbeta into a ternary complex with Ape and the AP-DNA. After incision by Ape, only Polbeta exhibits stable DNA binding. Kinetic experiments indicated that Ape accelerates the excision of 5'-terminal deoxyribose 5-phosphate by Polbeta. Thus, the two central players of the base excision repair pathway are coordinated in sequential reactions.

DNA Polymerase I↗

PubMed1995

Inhibition of nucleotide excision repair by the cyclin-dependent kinase inhibitor p21.

p21, a p53-induced gene product that blocks cell cycle progression at the G1 phase, interacts with both cyclin-dependent kinases and proliferating cell nuclear antigen (PCNA). PCNA functions as a processivity factor for DNA polymerases delta and epsilon and is required for both DNA replication and nucleotide excision repair. Previous studies have shown that p21 inhibits simian virus 40 (SV40) DNA replication in HeLa cell extracts by interacting with PCNA. In this report we show that p21 blocks nucleotide excision repair of DNA that has been damaged by either ultraviolet radiation or alkylating agents, and that this inhibition can be reversed following addition of PCNA. We have determined that p21 is more effective in blocking DNA resynthesis than in inhibiting the excision step. We further show that a peptide derived from the carboxyl terminus of p21, which specifically interacts with PCNA, inhibits polymerase delta-catalyzed elongation of DNA chains almost stoichiometrically relative to the concentration of PCNA. When added at higher levels, this peptide also blocks both SV40 DNA replication and nucleotide excision repair in HeLa cell extracts. These results indicate that p21 interferes with the function of PCNA in both in vitro DNA replication and nucleotide excision repair.

Amino Acid Sequence↗

PubMed1996

Overproduction, purification, and characterization of the XPC subunit of the human DNA repair excision nuclease.

Xeroderma pigmentosum complementation group C gene (XPC) encodes a protein of 125 kDa which is present in a tight complex with a 58-kDa protein encoded by the human homolog of the yeast RAD23 gene, HHR23B (Masutani, C., Sugasawa, K., Yanagisawa, J., Sonoyama, T., Ui, M., Enomoto, T., Takio, K., Tanaka, K., van der Spek, P. J., Bootsma, D., Hoeijmakers, J. H. J., and Hanaoka, F.(1994) EMBO J. 13, 1831-1843). The XPC-HHR23B complex is required for excision of thymine dimers from DNA in a human excision nuclease system reconstituted from purified proteins. In order to understand the role of the XPC-HHR23B complex in excision repair, we have overexpressed each subunit alone and the heterodimer in heterologous systems, purified them, and characterized their biochemical properties. We find that both XPC and the heterodimer bind DNA with high affinity and UV-damaged DNA with slightly higher preference. Surprisingly, we find that the XPC subunit alone is sufficient for reconstitution of the human excision nuclease and that the HHR23B subunit has no detectable effect on the excision activity of the reconstituted system.

Animals↗

PubMed1998

Excision of C-4'-oxidized deoxyribose lesions from double-stranded DNA by human apurinic/apyrimidinic endonuclease (Ape1 protein) and DNA polymerase beta.

Oxidative damage to DNA deoxyribose generates oxidized abasic sites (OAS) that may constitute one-third of ionizing radiation damage. The antitumor drug bleomycin produces exclusively OAS in the form of C-4-keto-C-1-aldehydes in unbroken DNA strands and 3'-phosphoglycolate esters terminating strand breaks. We investigated whether two human DNA repair enzymes can mediate OAS excision in vitro: Ape1 protein (the main human abasic endonuclease (also called Hap1, Apex, or Ref1)) and DNA polymerase beta, which carries out both the abasic excision and the resynthesis steps. We used a duplex oligonucleotide substrate with one main target for bleomycin-induced damage. Ape1 catalyzed effective incision at the C-4-keto-C-1-aldehyde sites at a rate that may be only a few-fold lower than incision of hydrolytic abasic sites at the same location. Consistent with several previous studies, Ape1 hydrolyzed 3'-phosphoglycolates 25-fold more slowly than C-4-keto-C-1-aldehydes. DNA polymerase beta excised the 5'-terminal OAS formed by Ape1 incision at a rate similar to its removal of unmodified abasic residues. Polymerase beta-mediated excision of 5'-terminal OAS was stimulated by Ape1 as it is for unmodified abasic sites. Escherichia coli Fpg (MutM) protein also excised 5'-terminal OAS, but in our hands, the RecJ protein did not. These observations help define mammalian pathways of OAS repair, point to interactions that might coordinate functional steps, and suggest that still unknown factors may contribute to removal of 3'-phosphoglycolate esters.

Base Sequence↗

PubMed2001

Damaged DNA-binding protein DDB stimulates the excision of cyclobutane pyrimidine dimers in vitro in concert with XPA and replication protein A.

Human cells contain a protein that binds to UV-irradiated DNA with high affinity. This protein, damaged DNA-binding protein (DDB), is a heterodimer of two polypeptides, p127 and p48. Recent in vivo studies suggested that DDB is involved in global genome repair of cyclobutane pyrimidine dimers (CPDs), but the mechanism remains unclear. Here, we show that in vitro DDB directly stimulates the excision of CPDs but not (6-4)photoproducts. The excision activity of cell-free extracts from Chinese hamster AA8 cell line that lacks DDB activity was increased 3-4-fold by recombinant DDB heterodimer but not p127 subunit alone. Moreover, the addition of XPA or XPA + replication protein A (RPA), which themselves enhanced excision, also enhanced the excision in the presence of DDB. DDB was found to elevate the binding of XPA to damaged DNA and to make a complex with damaged DNA and XPA or XPA + RPA as judged by both electrophoretic mobility shift assays and DNase I protection assays. These results suggest that DDB assists in the recognition of CPDs by core NER factors, possibly through the efficient recruitment of XPA or XPA.RPA, and thus stimulates the excision reaction of CPDs.

Base Sequence↗

PubMed2001

Treatment of primary lymphoma of the lacrimal gland by surgical excision alone: A 5-year follow-up study.

PURPOSE. To evaluate the long-term efficacy of surgical excision alone in the treatment of non-Hodgkin(1)s lymphoma localized to the lacrimal gland. MATERIALS AND METHODS. Thirteen patients with primary lacrimal gland lymphoma were included. The presumptive diagnosis was based on: (1) The painless and relatively slow onset of unilateral lacrimal gland swelling, mostly in elderly adults; (2) The CT pattern of a soft tissue mass in the lacrimal gland region with defined margins and molds to the globe; (3) The negative results of systemic work-up. The involved lacrimal gland was excised via an anterior trans-septal approach in 12 cases and by lateral canthotomy, upper cantholysis, and a trans-periosteal approach in one case. Following histopathologic confirmation of the diagnosis, no supplemental therapy was given. The patients were followed for a minimum of 5 years (5-8 years). RESULTS. In all patients, the excised lacrimal gland lymphoma was firm, nodular and appeared encapsulated. The histologic subtypes of the excised masses were: low-grade lymphomas in 11 cases (7 small lymphocytic, 3 plasmacytoid lymphocytic, 1 follicular small cleaved) and intermediate grade in 2 cases (1 follicular large cell and 1 diffuse small cleaved). No evidence of local recurrence or systemic dissemination was reported during the follow-up period in any of the patients. CONCLUSIONS. Surgical excision of the tumor is a new curative technique for lymphoma localized to the lacrimal gland without any other orbital or systemic involvement. By this technique, orbital radiotherapy and its potential ocular complications can be avoided. However, more study is recommended.

Journal Article↗

PubMed2003

A randomized study comparing DCR with and without excision of the posterior mucosal flap.

AIM: A prospective randomized study was carried out to compare the success rate of external dacryocystorhinostomy (DCR) with and without excision of the posterior sac mucosal flap. METHODS: Forty patients (Group A) underwent DCR without excision of the posterior sac mucosal flap, and the results obtained were compared with those of another series of 40 patients (Group B) where DCR was performed with excision of the posterior sac flap. A large posterior flap was excised from the lacrimal sac and a large, mobile, anteriorly-hinged, nasal mucosal flap was fashioned. The latter was joined to the anterior sac flap using a 6/0 double-armed polyglycolic acid suture. RESULTS: Four patients in Group B had signs and symptoms of tearing (90% success rate) at the end of the follow-up period (mean 11.05 months, range 9-14 months). Group A had six patients with recurrent signs and symptoms (85% success rate) by the end of a mean follow-up period of 11.3 months (range 9-14 months). CONCLUSION: Excision of the posterior sac mucosa may improve the success rate of external DCR.

Adult↗