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PubMed1993

Mechanisms of flagellar excision. I. The role of intracellular acidification.

It has previously been shown that exposure of Chlamydomonas to low pH induces the cells to shed their flagella. In the present paper we report that a 30-s treatment with 20 mM acetic, carbonic, formic, or benzoic acid at pH 4.0 will induce flagellar excision. In contrast, 20 mM concentrations of the stronger aspartic, phosphoric, citric, and tartaric acids (pH 4) do not induce excision. Further, the excision efficacy of acetate is a function of the concentration of protonated acetate. Thus, excision correlates with the presence of a protonated, membrane-permeant species of acid. Relative to acetate, the more permeant benzoate induces excision at a much lower concentration of protonated acid. We conclude that a flux of acid into the cell is the signal for excision. Previous work has shown that detergent-permeabilized cells excise their flagella in response to calcium but not in response to low pH. This suggests that the acidification of intact cells triggers excision by stimulating an increase in intracellular calcium. We have previously reported that the source of this calcium might be IP3-sensitive. In our model for the mechanism of pH-induced flagellar excision, a flux of acid into the cell activates phospholipase C, leading to IP3 production, the activation of an IP3-gated calcium channel (located on either an intracellular or surface membrane), and an increase in cytosolic calcium, which is the trigger of flagellar excision.

Acids↗

PubMed2005

Intraoperative ultrasound-guided excision of nonpalpable breast lesions.

The methods commonly used to guide surgical excision of impalpable breast lesions include preoperative placement of hookwires, carbon injections, and, more recently, radioisotope injections. However, all of these techniques have disadvantages, not the least of which is subjecting the patient to an additional stressful and often traumatic procedure preoperatively. The use of intraoperative ultrasound to guide the excision of sonographically visible impalpable lesions is a new technique that avoids the need for a preoperative localization procedure. This report describes one of the author's (I.B.) personal series of ultrasound-guided breast excisions, collating data collected prospectively, and reviews the efficacy of this technique. Data in relation to 115 ultrasound guided breast excisions performed in 103 patients were reviewed. The technique of using a high-frequency real-time ultrasound probe intraoperatively to localize and guide excision of breast abnormalities is described. There were no failed excisions, as confirmed by specimen sonography, pathology findings, and/or follow-up ultrasound. Breast malignancies comprised 42% of all excised lesions, and of these, adequate margins of excision were achieved at the first operation in 93% of cases. Direct ultrasound localization of the lesion at the time of surgery allowed optimal placement of the incision and eliminated delays in operating time because specimens did not have to be sent to the Radiology Department for confirmation of excision. Intraoperative ultrasound-guided excision is a safe and efficient technique in the management of impalpable, sonographically visible breast lesions, and early reports in the world literature support the findings of this series, which show it to have significant advantages over other current methods, particularly with respect to a reduction in patient anxiety and improved surgical resection margins.

Adolescent↗

PubMed2002

Excision of laparoscopic port sites increases the likelihood of wound metastases in an experimental model.

BACKGROUND: Case reports of patients developing tumor metastases at port sites following laparoscopic surgery have prompted the development of preventive strategies to address this potential problem, including local excision of the port sites. While it has been suggested that this strategy could be used clinically, its efficacy has not been established. METHODS: Twenty four immune-competent Dark Agouti rats underwent laparoscopy and standardized intraperitoneal laceration of an implanted abdominal flank tumor, using an established laparoscopic cancer model. Rats were randomized to either control (n = 12) or wound excision (n = 12) groups. Both groups underwent laparoscopy using carbon dioxide (CO2) insufflation and two mini-laparoscopy ports. In the wound excision group, one of the port site wounds was excised following desufflation of the abdominal cavity. One week later, the port site wounds were excised for histological examination. RESULTS: Wound involvement with tumor was significantly more common following wound excision than with untreated control wounds (nine of 12 vs two of 12, p = 0.002). In the wound excision group, tumor metastases arose preferentially in the excised port site wound. CONCLUSION: This study suggests that excision of laparoscopy port site wounds following laparoscopic surgery for cancer does not prevent the subsequent development of port site tumors. Furthermore, the excision of port sites may actually increase the risk of tumor metastases arising in port sites, suggesting that the clinical application of this strategy should be avoided pending further evaluation.

Abdominal Neoplasms↗

PubMed1996

Loop electrosurgical excision procedure for squamous intraepithelial lesions of the cervix: advantages and potential pitfalls.

OBJECTIVE: to evaluate the advantages and pitfalls of the loop electrosurgical excision procedure as applied to the diagnosis and treatment of cervical cancer precursors. METHODS: Loop electrosurgical excision procedure using local anesthesia and colposcopic guidance was performed in an outpatient clinical setting in 1189 consecutive patients referred for colposcopy for an abnormal Papanicolaou smear during a period of 4 years. RESULTS: Of the 1189 patients, 915 (77%) were managed in one sitting with the "see and treat" approach, and in 274 patients endocervical curettage and cervical biopsies preceded loop electrosurgical excision procedure. One hundred nineteen (10%) patients were lost to follow-up. Twenty-one patients had either adenocarcinoma in situ (15) or microinvasive squamous cell carcinoma (six) in the loop electrosurgical excision procedure specimen, whereas the electroexcised specimens contained no lesional tissue in 166 (14%) patients. Cure (ie, disease-free at 6 months or longer) was observed in 92% of the 883 evaluable patients after a single treatment and 95% after a repeat loop electrosurgical excision procedure. High-grade squamous intraepithelial lesion was successfully treated with loop electrosurgical excision procedure in 287 (93%) of 309 patients. Complications, mainly intra- and postoperative bleeding, occurred in 7% of the patients. In most loop electrosurgical excision procedure-negative cases, the referral cytologic diagnosis or colposcopy and/or history were false-positive on review, or the biopsies performed before loop electrosurgical excision procedure removed smaller areas of abnormal tissue. CONCLUSION: Loop electrosurgical excision procedure using the see and treat approach should be limited to cytologically and colposcopically unequivocal intraepithelial lesions, and depth of excision should be controlled by colposcopy using loop electrodes of appropriate size. In doubtful cases, particularly in the young patient, disease should be ascertained by expert histology and colposcopy before definite therapy. Loop electroexcision represents an attractive means of diagnosing and treating cervical cancer precursors.

Adenocarcinoma↗

PubMed1981

Three Tn10-associated excision events: relationship to transposition and role of direct and inverted repeats.

We describe three related DNA alterations associated with transposon Tn10: precise excision of Tn10, nearly precise excision of Tn10 and precise excision of the nearly precise excision remnant. DNA sequence analysis shows that each of these alterations results in excision of all or part of the Tn10 element, and each involves specific repeat sequences at or near the ends of the element. Furthermore, all three events are structurally analogous: in each case, excision occurs between two short direct-repeat sequences, with resulting deletion of all intervening material plus one copy of the direct repeat; and in all three cases, the direct repeats involved occur at either end of an inverted repeat. Analysis of mutant Tn10 elements and characterization of bacterial host mutations suggest that all three types of excision events occur by pathways that are fundamentally distinct from the pathway(s) for Tn10-promoted transposition and other DNA rearrangements (deletions and inversions) actively promoted by the element. In addition, precise excision and nearly precise excision appear to occur by very closely related or identical pathways; and several lines of evidence suggest that the 1400 bp inverted repeats at the ends of Tn10 may play a structural role in both of these events. The third excision event appears to occur by yet another pathway.

Base Sequence↗

PubMed2006

Wound healing after excision of mantle tissue from the Akoya pearl oyster, Pinctada fucata.

Pearl oysters are usually sacrificed to donate mantle tissue for pearl production. However, if oysters are anaesthetized, they are able to survive mantle excision and regenerate this tissue. Mantle excision causes a large wound and severs the pallial artery that necessitates rapid wound repair to avoid death by bleeding. This study was undertaken to assess the wound healing process in the mantle of the Akoya pearl oyster, Pinctada fucata, following mantle excision. Forty-seven P. fucata were relaxed with 2.5 mL L(-1) propylene phenoxetol before mantle tissue was excised. Oysters were relaxed and sacrificed 1, 3, 6, 12, 25, 36, 48, 66, 80 and 105 h after excision to assess mantle healing using histological techniques. Muscular contraction that effectively reduced the size of the wound was observed within 1 h after mantle excision. Accumulation of haemocytes and connective tissue occurred 3-6 h after excision and wound plugging was achieved within 6 h of excision. Proliferation of epithelial cells to cover the wound site was observed within the first 25 h after mantle excision and growth of connective tissue and formation of the pallial artery were observed within 105 h after mantle excision.

Animals↗

PubMed2005

The efficiency of hypoxanthine excision by alkyladenine DNA glycosylase is altered by changes in nearest neighbor bases.

Alkyladenine DNA glycosylase (AAG) excises a structurally diverse group of damaged purines including hypoxanthine, 1,N(6)-ethenoadenine, 3-methyladenine, and 7-methylguanine from DNA to initiate base excision repair at these sites. Excision occurs in an enzyme.DNA complex in which the damaged base is flipped out of the DNA helix into the enzyme active site. To determine whether local DNA sequence could affect the overall efficiency of excision of hypoxanthine from DNA, single-turnover kinetics of excision, AAG.DNA binding, and melting temperatures were measured for DNA substrates that differed in the base pairs immediately 5' and 3' to hypoxanthine. When Hx was flanked by a 5'G and a 3'C, the efficiency of excision was reduced dramatically in comparison to a duplex containing a 5'T and 3'A. The reduction in excision efficiency was largely due to a decrease in binding affinity of AAG for DNA. The overall effect of GC versus TA nearest neighbors was to magnify the difference in the efficiencies of excision of Hx from pairs with thymine and difluorotoluene from a factor of 5 to a factor of about 100. In general, DNA substrates that were more stable as indicated by higher melting temperatures gave reduced efficiencies of excision of Hx. These results are discussed in terms of a model in which the relative stabilities of base-flipped versus unflipped complexes contribute the overall efficiency of excision and substrate specificity of AAG.

Base Pairing↗

PubMed2005

Comparative analysis of minimally invasive microductectomy versus major duct excision in patients with pathologic nipple discharge.

BACKGROUND: Minimally invasive techniques are being used increasingly in patients with benign and malignant breast diseases. The purpose of this study was to compare the diagnostic yield of 2 groups of patients who underwent either minimally invasive microductectomy or major duct excision for pathologic nipple discharge. METHODS: Two hundred thirty-five patients who underwent nipple exploration and duct excision and were part of an institutional review board-approved database were included in this retrospective analysis. Preoperative imaging, ductal washing cytology, surgical specimen size, and final histopathology were compared among 95 patients who underwent microductectomy by using intraoperative ductoscopy and 140 patients undergoing standard major duct excision. RESULTS: Mean age of patients undergoing microductectomy was 53 versus 55 years in patients undergoing major duct excision. Preoperative mammogram was negative or benign in 92% and suspicious in 8% of patients in both the microductectomy group and the major duct excision group. A ductal abnormality was identified by preoperative ductography in 43 of 56 (77%) patients in the microductectomy group versus 74 of 92 (80%) patients in the major duct excision group. Ductal cytology was benign in 81% and 80% of patients tested, respectively. Mean specimen size was significantly smaller in patients who underwent microductectomy (9.2 cm3) as compared with major duct excision (12.6 cm3). Although the percentage of patients with atypical ductal hyperplasia or lobular carcinoma in situ was similar among the 2 groups (9% vs 10%), only 3 of 95 (3%) patients within the microductectomy group were found to have carcinoma within the resection specimen as compared with 12 of 140 (9%) within the major duct excision group (P = .03). Mean specimen size of the patients diagnosed with carcinoma was 8.6 cm(3) in the microductectomy group as compared with 15.5 cm3 in the major duct excision group (P = .014). CONCLUSIONS: These data confirm that patients who present with single duct pathologic nipple discharge usually have benign pathology as the etiology. However, in a small percentage of patients an occult carcinoma might be present. Major duct excision appears to detect a higher percentage of occult carcinoma when compared with minimally invasive microductectomy, which might be related to the larger sample size of the resection specimen.

Aged↗

PubMed1996

Risk of cervical stenosis after large loop excision or laser conization.

OBJECTIVE: To assess the frequency of cervical stenosis in patients treated by laser conization or the loop electrosurgical excision procedure and to determine the preoperative and therapeutic factors associated with its occurrence. METHODS: Two hundred fifty-five women treated by laser conization and 277 treated by loop electrosurgical excision procedure were followed regularly by postoperative colposcopy for mean periods of 38 and 16 months, respectively. Stenosis was defined as cervical narrowing that prevented insertion of a 2.5-mm Hegar dilator. RESULTS: Thirty-eight cases of cervical stenosis, of which seven were complete, were diagnosed up to 28 months after treatment. The risk of postoperative cervical stenosis was higher for patients over 50 years of age (relative risk [RR] 3.07, 95% confidence interval [95% CI] 1.30, 7.26; P = .031), for those with a totally endocervical lesion (RR 3.79, 95% CI 1.88, 7.62; P = .001), for those with an excision 20 mm high or greater (RR 2.96, 95% CI 1.63, 5.38; P = .005), and for those with laser conization (RR 2.35, 95% CI 1.24, 4.46; P = .009). Parity, menopause, previous treatment for cervical intraepithelial neoplasia, satisfactory colposcopy, size of the lesion, its histologic diagnosis, and the extent of excision did not increase the risk for cervical stenosis. Excision was not as high with loop electrosurgical excision as with laser conization (14.3 +/- 5.0 mm versus 20.2 +/- 6.0 mm). The height of excision (RR 1.95, 95% CI 1.02, 3.76; P = .04) and a totally endocervical lesion (RR 5.07, 95% CI 1.96, 14.44; P = .001) were the only independent factors associated with postoperative stenosis identified by a multivariate analysis using logistic regression. CONCLUSION: The height of excision and a totally endocervical lesion were the main factors associated with cervical stenosis. The decreased risk associated with the loop electrosurgical excision procedure seems to be due to a shorter endocervical excision.

Adolescent↗

PubMed1997

Photoreversal of UV-potentiated glutamine tRNA suppressor mutations in excision proficient Escherichia coli.

UV-irradiated excision proficient Escherichia coli were exposed to light for photoenzymatic reversal (PR) of cyclobutane pyrimidine dimers (CPD) and assayed for reversion mutation (glutamine tRNA suppressor mutations) on semi-enriched medium or on the same medium containing acriflavine to inhibit excision repair. The initial mutation frequency without PR was relatively greater when assayed with acriflavine, and this difference increased as larger UV fluences were used. The PR kinetics were first order and about the same or slightly faster when cells were assayed with acriflavine (after 15, 30 or 45 J/m2, respectively). The results indicated mutation targeting by CPD in excision proficient cells. These results and conclusion contrast sharply with the original study of this type done several years ago. PR kinetics were considerably slower with assays containing acriflavine, sustaining the idea that PR causes repair of non-dimer targeting lesions by enhancing excision repair. To explain this contrast we devised a fluence-decrement rate for estimating the effectiveness of PR and measured PR-dependent excision repair (PER) as the difference in the fluence-decrement rate with excision proficient and deficient cells. PER was more evident when cells were prepared as in the original study but was still an insufficient factor. More importantly, the original study included a component of indirect photoreactivation or photoprotection (using unfiltered PR light) which accentuated the role of excision repair. Taking these factors into account, the original data also are consistent with the model that glutamine tRNA suppressor mutations produced by UV-mutagenesis in excision proficient E. coli result from targeting by CPD just as in excision defective cells. Thus, with regards to a common UV mutation assay, there does not appear to be two types of targeting lesion depending on excision proficiency.

DNA Repair↗

PubMed2000

Deep shave excision of macular melanocytic nevi with the razor blade biopsy technique.

BACKGROUND: Shave excision is an established surgical method for removing benign skin lesions for cosmetic and functional reasons. Usually superficial shave excision is performed with a common scalpel blade for the removal of papular nevi. However, there is little known about deep shave excision of macular melanocytic nevi with the razor blade technique. OBJECTIVE: The present study was undertaken to evaluate the cosmetic outcome of deep shave excision of macular melanocytic nevi with the razor blade technique. Moreover, its potency for sufficient removal of these lesions was investigated. METHODS: Within routine skin cancer screening 45 outpatients with a total of 77 macular melanocytic nevi were prospectively recruited. Deep shave excisions of these lesions were performed with a double-edged razor blade followed by chemical hemostasis. Histologically all specimens were processed and evaluated in a routine manner. After 6 months the physician and patients evaluated the shave sites for cosmetic outcome with a score graded from 1 to 4 (1 = excellent; 2 = good; 3 = moderate; 4 = poor). RESULTS: Histologically 88% (68 of 77) of the melanocytic lesions were described as completely excised and 60% (46 of 77) were diagnosed as atypical melanocytic nevi; 12% (9 of 77) of the nevi were incompletely excised on the depth. On average, the deep margin of the specimens (n = 77) was 0.5 mm (range 0-1.8 mm) and the lateral margin was 2 mm (range 0.3-8.2 mm). After 6 months 56 shave sites could be reassessed. We observed mild hypopigmentation in 52% (29 of 56), hyperpigmentation in 32% (18 of 56), and erythema in 23% (13 of 56). Recurrent nevi occurred in 13% (7 of 56). The evaluation of the cosmetic outcome by the patients (mean score 1.7) achieved better results than the evaluation by the physician (mean score 2.5). The cosmetic results showed no significant (P >.05) differences in various anatomic sites. CONCLUSION: Our data confirm that deep razor blade excision presents a highly useful and inexpensive method for the removal of macular melanocytic nevi that yields adequate specimens for pathologic interpretation. We consider that shave excision with the razor blade technique is potentially much less scarring than full-thickness scalpel excisions of nevi. In particular, this is of great significance for patients with multiple nevi, such as dysplastic nevi syndrome.

Adolescent↗

PubMed2002

Mismatch repair in human nuclear extracts. Time courses and ATP requirements for kinetically distinguishable steps leading to tightly controlled 5' to 3' and aphidicolin-sensitive 3' to 5' mispair-provoked excision.

Mismatch repair (MMR) systems enhance genomic stability by correcting DNA replication errors. The events in mammalian MMR pathways remain poorly understood. Using HeLa cell nuclear extracts, we analyzed correction of mispairs in circular DNA substrates with single defined nicks and measured excision in the absence of exogenous dNTPs by annealing specific oligonucleotide probes. In reactions initiated by concomitant temperature shift and addition of ATP or Mg(2+) to otherwise complete mixtures on ice, ATP-initiated excision and final error correction lagged behind Mg(2+)-initiated reactions, suggesting a very early requirement for ATP but not its hydrolysis. Subsequent stable commitment (resistance to added excess competitor substrate) began within 30 s, required hydrolyzable ATP, and plateaued after 60-70 s. This may reflect formation of hydrolysis-dependent translocating and/or pre-excision complexes. Excision along shorter nick-mispair paths began 15 s later than commitment. Both 3' to 5' and 5' to 3' excision gaps appeared at rates of approximately 0.0055 of final yields per second, respectively, 30 or 2.5 times the nonspecific excision rates. The lag between 3' to 5' excision gaps at two different positions yielded an excision progress rate of 5.2 nucleotides/s. In both substrates, corrected products appeared at fractional rates of 0.0027 of final yield per second. Aphidicolin, known to inhibit both the DNA synthesis and 3' to 5' exonuclease activities of polymerases delta and epsilon, reduced appearance of 3' to 5' excision tracts roughly 4-fold at 90 microm but had no effect on 5' to 3' excision.

Adenosine Triphosphate↗

PubMed2002

Atypical ductal hyperplasia and atypia of uncertain significance in core biopsies from mammographically detected lesions: correlation with excision diagnosis.

AIMS: To assess: (1) the prevalence of reporting of atypical ductal hyperplasia (ADH) and intraductal atypia of uncertain significance (AUS) in a series of core biopsies from mammographically detected lesions, (2) the proportion of cases where excision revealed breast carcinoma, and (3) whether any diagnoses should be revised on review. METHODS: Breast core biopsy reports from the Sir Charles Gairdner Hospital Breast Assessment Centre for the years 1999-2000 were retrieved. Slides from cases reported as ADH or AUS were reviewed as well as slides from the excision biopsies. RESULTS: There were 1048 core biopsies from 911 women. Breast carcinoma was diagnosed in 197 samples (18.8%) including 88 with invasive carcinoma (8.4%), 109 with ductal carcinoma in situ (DCIS) (10.4%). Three biopsies (0.3%) 'suspicious' of invasive carcinoma proved to be so. Of 52 samples (5.0%) with a diagnosis of ADH or AUS, 46 were excised, showing seven invasive carcinomas, 15 DCIS, 11 ADH, two lobular carcinoma in situ (LCIS), nine fibrocystic change (FCC), one mucocoele-like lesion and one fibroadenoma. The 22 malignancies represented 47.8% of the excised lesions. On review, seven of the 52 original core diagnoses were downgraded to benign hyperplasia. Five underwent excision, revealing two FCC, one complex sclerosing lesion, and two incidental lesions unrelated to the mammographic abnormality, including a microscopic tubular carcinoma and a focus of LCIS. In one case reviewed as unsatisfactory, excision showed invasive carcinoma. Lesions of particular interest included a case of high-grade DCIS with local regression in the core biopsy (so-called 'bumt out DCIS'), and one case diagnosed on excision as micropapillary ADH, where the review diagnosis was micropapillary DCIS. CONCLUSIONS: ADH and AUS were reported in 5.0% of biopsies. There was a high rate of carcinoma (47.8%) in subsequent excisions. Very few diagnoses were revised on review. Current protocols for excision of lesions with a 14-gauge core biopsy diagnosis of ADH/AUS appear justified. Literature review suggests that vacuum-assisted core sampling with 11-gauge needles will not remove the need for excision. Further study of local regression of DCIS and micropapillary lesions will be worthwhile.

Aged↗

PubMed2005

Risk factors for incomplete excision of squamous cell carcinomas.

OBJECTIVE: The aim of this study was to identify risk factors for incomplete excision of squamous cell carcinomas (SCCs). PATIENTS AND METHODS: A cross-sectional study of 369 patients who underwent a primary excision of SCCs was performed within an outpatient and a hospital plastic surgery department setting. RESULTS: Incomplete excision occurred in 25 of 369 primary excisions of SCC (6.8%). Location of the tumors on the forehead, temples, peri-auricular region, ears, cheeks, nose, lips or neck was significantly associated with incomplete excision of the tumors. In particular, high incomplete excision proportions were observed for tumors located on the ears (16.7%), neck (16.7%), temples (11.1%), nose (10.8%) or lips (7.1%). Incomplete excision of SCC was associated with the setting of the operation in the hospital as compared to ambulatory settings (p = 0.046) and was inversely associated with the specimen thickness (p = 0.002). There was no statistically significant association between incomplete excision of SCC and gender, age, clinical appearance of the lesion (suspected SCC vs other diagnoses), differentiation pattern, diameter of the tumor, length or width of the excised specimen, solar changes or ulceration. CONCLUSION: We recommend that in patients with SCCs located in the forehead, temples, periauricular region, ears, cheeks, nose, lips or neck surgeons should commence particular surgical measures to avoid inadequate excisions of the tumors. In particular, surgeons should use wider excisional margins in tumors located in the embryonic fusion planes (e.g. eyelids and naso-labial folds).

Aged↗

PubMed1985

Mismatch repair mutations of Escherichia coli K12 enhance transposon excision.

Excision of the prokaryotic transposon Tn10 is a host-mediated process that occurs in the absence of recA function or any transposon-encoded functions. To determine which host functions might play a role in transposon excision, we have isolated 40 mutants of E. coli K12, designated tex, which increase the frequency of Tn10 precise excision. Three of these mutations (texA) have been shown to qualitatively alter RecBC function. We show that 21 additional tex mutations with a mutator phenotype map to five genes previously identified as components of a methylation-directed pathway for repair of base pair mismatches: uvrD, mutH, mutL, mutS and dam. Previously identified alleles of these genes also have a Tex phenotype.--Several other E. coli mutations affecting related functions have been analyzed for their effects on Tn10 excision. Other mutations affecting the frequency of spontaneous mutations (mutT, polA, ung), different excision repair pathways (uvrA, uvrB) or the state of DNA methylation (dcm) have no effect on Tn10 excision. Mutations ssb-113 and mutD5, however, do increase Tn10 excision.--The products of the mismatch correction genes probably function in a coordinated way during DNA repair in vivo. Thus, mutations in these genes might also enhance transposon excision by a single general mechanism. Alternatively, since mutations in each gene have qualitatively and quantitatively different effects on transposon excision, defects in different mismatch repair genes may enhance excision by different mechanisms.

Bacterial Proteins↗

PubMed2001

Control of DNA excision efficiency in Paramecium.

Programmed excision of internal eliminated sequences (IESs) occurs at thousands of sites in ciliate genomes. How this is controlled is largely unknown. Here, we report the characterization of the non-efficiently excised 156psiG-11 IES from Paramecium primaurelia strain 156 and that of the efficiently excised 168psiG-11 IES, an allelic variant from strain 168. Then, we report a genetic and molecular analysis of IES excision efficiency in F(1) progeny derived from interstrain crosses and in F(2) homozygous progeny derived from F(1) autogamy. IES 168psiG-11 excision efficiency was approximately 100% in all cases. IES 156psiG-11 excision efficiency was 19 +/- 13% in F(1) progeny and 0.6 +/- 1.1% in F(2) progeny. No trans-excision event between IESs 156psiG-11 and 168psiG-11 was detected within the F(1) progeny. These data demonstrate that the excision efficiency of this IES is variable and controlled by a cis-acting element. This should encompass positions 8 and/or 9 of the right IES end, which display allele differences. Finally, the 30-fold stimulation of IES 156psiG-11 excision efficiency within F(1) progeny relative to F(2) progeny demonstrates that Paramecium IES excision efficiency is sensitive either to a conjugation-specific trans-acting factor provided by the zygotic genome, or to homologous chromosome cross-talk.

Alleles↗

PubMed2002

Circular excision of hemangioma and purse-string closure: the smallest possible scar.

Localized cutaneous infantile hemangioma acts like a tissue expander. This rapidly growing tumor can destroy elastic fibers or cause ulceration resulting in telangiectases, cutaneous laxity, scarring, and fibrofatty residuum. Although surgeons may dispute indications and timing, most would agree that the scar of resection should be minimized. For this reason, circular excision and purse-string closure is particularly applicable for hemangioma at any stage of its evolution. The purposes of this study were to: (1) analyze the results of circular excision/purse-string closure in all three phases of the life cycle of hemangioma; (2) quantify dimensional changes after resection; and (3) compare the scars after theoretical single-stage lenticular excision with those after staged circular excision/purse-string closure. The authors retrospectively analyzed their experience in 25 children with localized hemangioma who underwent circular excision/purse-string closure from 1997 to 2000. Each hemangioma was measured preoperatively and the scars were measured at most recent follow-up (minimum, 6 months). Preoperative and postoperative dimensions were analyzed using SPSS statistical software. The study included 22 girls and three boys, with an average time to follow-up evaluation of 13.1 months. Twenty-one lesions were in the face and scalp, and five were in the extremity. Five tumors were resected in the proliferative phase (either because of ulceration, bleeding, or visual complications) and 21 were excised in the involuting or involuted phase. Six patients had a second-stage procedure: three had another circular excision and three had later lenticular excision. After single circular excision/purse-string closure, the mean long-axial diameter (length) decreased by 45 percent, the mean short-axial width (width) decreased by 73 percent, and the mean scar area was only 15 percent of the original area. All these differences were statistically significant (p = 0.001). The average width/length ratio decreased by 50 percent, indicating a tendency for scars to linearize. There was no difference in linearization for the three phases of hemangioma (p > 0.05); extremity scars became more linear that those on the face (p = 0.01). The authors devised a formula for scar length after lenticular excision/linear closure, assuming a conventional excisional ratio of 3:1 for a circular lesion. Using this equation, the authors predicted that mean scar length after circular excision, followed by lenticular excision, would be 72 percent shorter than the calculated scar that would result from conventional lenticular excision. In three patients who underwent this two-stage approach, the resultant scar was 69 percent shorter. Circular excision of hemangioma and purse-string closure reduces both the longitudinal and transverse dimensions and converts a large circular lesion into a small ellipsoid scar. If subsequent revision to a linear scar is desirable, its length will be the same or slightly less than the diameter of the original lesion. No other excision and closure technique results in a smaller scar. Another advantage of this method is minimal distortion of surrounding structures.

Child↗

PubMed2003

Excision margins for nonmelanotic skin cancer.

Scientific evidence for advisable excision margins for nonmelanotic skin carcinoma is poorly documented. Recommended excision margins vary from 2 to 15 mm. A prospective study was performed on 150 skin lesions excised over a 9-month period in an outpatient facility at the authors' institution. Primary nonmelanotic skin lesions were clinically diagnosed as either basal cell carcinoma (nodular, superficial, infiltrating, or sclerosing) or squamous cell carcinoma (well, moderately, or poorly differentiated). Macroscopic surgical excision margins were individually assessed, measured, and excised. Histopathologic analysis was then independently performed to determine the correct diagnosis and to measure the actual microscopic lateral and deep excision margins.Sixty-one percent of lesions were basal cell carcinoma, 25 percent were squamous cell carcinoma, and 15 percent were benign or premalignant. Diagnostic accuracy was 81 percent for basal cell and 59 percent for squamous cell carcinoma. The average diameter of the basal cell carcinoma was 12.1 mm; 47 percent of these lesions had a diameter of less than 10 mm. The average diameter of the squamous cell carcinoma was 16.9 mm; 26 percent of these lesions had a diameter of less than 10 mm. The mean surgical margin was 4.2 mm (3.2 mm adjusted for shrinkage), whereas the mean microscopic lateral margin was 3.4 mm. Overall, complete excision was achieved for 98 percent of basal cell carcinoma and 100 percent of squamous cell carcinoma. The raw data were analyzed to assess the suitability of 1-, 2-, 3-, or 4-mm surgical excision margins. A 4-mm surgical margin would give a microscopic lateral margin beyond one microscopic high-power field (0.5 mm) in 96 percent of cases of basal cell carcinoma and in 97 percent of cases of squamous cell carcinoma. The authors recommend a 4-mm surgical margin as the optimal treatment for skin lesions clinically diagnosed as basal cell or squamous cell carcinoma that are suitable for excision in an outpatient facility. Well-demarcated lesions, such as a nodular basal cell carcinoma, may be excised with a 3-mm margin.

Adult↗