Incision Defect Research Articles

A Review of the Use of Buccal Fat Pad in Cleft Palate Repair.

To review the available evidence on the use of the Buccal Fat Pad in primary and secondary Cleft Palate repair. This is a narrative review. A computerized literature search was conducted for articles published till February 2022 using the Mesh phrases buccal fat pad AND cleft palate, Bichat's Fat pad AND cleft palate, buccal fat pad OR Bichats Fat pad AND cleft palate. A total of 35 articles were included in this review based on the set eligibility criteria. Most of the studies were retrospective case reviews (n = 16, 45.7%), and the aggregate number of patients from all included studies was 666. Reported uses of the buccal fat pad (BFP) in association with cleft palate repair include the closure of central cleft palate defect and nasal floor in primary cleft palate repair, oronasal fistula repair following primary repair of cleft palate, and closure of relieving incision defect in primary repair of cleft palate. Complications reported were 24 cases of Oronasal Fistula (ONF), 2 dehiscences, and 4 transient mucosal defects. The high success rate, vascularity, ease of tissue harvest, and low donor site morbidity all support its use as an adjunct flap in cleft palate repair, especially in the closure of wide palatal clefts, to prevent post-palatal repair fistula, wound contracture, and subsequently velopharyngeal insufficiency and possibly midface hypoplasia.

The effects of hysteroscopy and laparoscopy for scar diverticulum resection and suture on blood loss, operation time and antibiotic time

To evaluate the effect of hysteroscopy and suture on uterine scar diverticulum (CSD) after caesarean section and its influence on blood loss, operation time and antibiotic time. Eighty-nine patients with CSD were divided into observation group (n = 41 cases) and control group (n = 48 cases). Control group received laparoscopic scar diverticulum resection and suture, while the observation group received hysteroscopic resection of scar diverticulum. The operation time of the observation group was longer, while the bleeding volume and antibiotic administration time were significantly lower. The surgical treatment efficiency of the observation group (97.56%) was significantly higher. After treatment, the observation group’s diverticulum repair indexes (width, depth and lower uterine muscular layer thickness) were better than those of the control group (p<.05). Hysteroscopic resection of scar diverticulum in CSD reduces intraoperative blood loss and the risk of complications, shortens time of antibiotic administration, and promotes diverticulum repair. Impact Statement What is already known on this subject? Uterine scar diverticulum (CSD) after caesarean section, also called postoperative uterine incision defect (PCSD), is due to poor healing of the uterine incision after caesarean section. What do the results of this study add? Hysteroscopic resection of scar diverticulum in CSD has a significant clinical effect, which can effectively reduce intraoperative blood loss and the risk of complications, shorten the time of antibiotic administration, and promote diverticulum repair. What are the implications of these findings for clinical practice and/or further research? Clinical effect of hysteroscopic resection of scar diverticulum in CSD is significant.

Medium-long-term outcomes of saphenous vein graft in Peyronie surgery: Is there a need for new graft material?

AimWe present our results of tunical incision and saphenous graft surgery for men with short penis and who cannot have sexual relations due to curvature linked to chronic Peyronie plaques. IntroductionPeyronie disease is a chronic process where fibrotic plaques form in the tunica albuginea. The plaques cause pain in the acute period and cause the penis to bend after inflammation ends. Surgical procedures are required for curvature>30°. Saphenous vein graft (SVG) replacement is an alternative method for tunical plaque incision defect. Material-methodThe outcomes for 71 patients with TI+SVG surgery were retrospectively assessed. Plaque features (curvature angle, location, direction of curve and tunical defect diameter), operative and postoperative properties (surgery duration, recurrent curvature, penis shortening, glans hypoesthesia, satisfaction score, follow-up duration), preoperative–postoperative penis length and IIEF-5 score differences were assessed. ResultsMean age was 61.12±7.9 (45–75) years, mean curvature angle was 62.0±14.7 (50–90), location was mid-penile for 46 (65%), with angulation direction toward the dorsal for 37 (52%), and the defect area after tunical incision was 15.5±3.9 (10–23) cm2. With mean follow-up duration of 37±9.4 months, 9 patients had re-curvature (13.2%), 8 had short penis (11.3%) and 7 had ED identified (9.4%). Total penis straightening was present for 86.8%, with patient satisfaction score of 21.1±4.4 (8–25). ConclusionThe TI+SVG method is an effective method for Peyronie surgery in the medium-long term.

Abdominal incision defect following AAA-surgery (AIDA): 2-year results of prophylactic onlay-mesh augmentation in a multicentre, double-blind, randomised controlled trial

The reported incidence of incisional hernia following repair of abdominal aortic aneurysm (AAA) via midline laparotomy is up to 69%. This prospective, multicenter, double-blind, randomised controlled trial was conducted at eleven hospitals in Germany. Patients aged 18 years or older undergoing elective AAA-repair via midline incision were randomly assigned using a computer-generated randomisation sequence to one of three groups for fascial closure: with long-term absorbable suture (MonoPlus®, group I), long-term absorbable suture and onlay mesh reinforcement (group II) or extra long-term absorbable suture (MonoMax®, group III). The primary endpoint was the incidence of incisional hernia within 24 months of follow-up, analysed by intention to treat. Physicians conducting the postoperative visits and the patients were blinded. Between February 2011 and July 2013, 104 patients (69.8 ± 7.7 years) were randomised, 99 of them received a study intervention. The rate of incisional hernia within 24 months was not significantly reduced with onlay mesh augmentation compared to primary suture (p = 0.290). Furthermore, the rate of incisional hernia did not differ significantly between fascial closure with slow and extra long-term absorbable suture (p = 0.111). Serious adverse events related to study intervention occurred in five patients (5.1%) from treatment groups II and III. Wound healing disorders were more frequently seen after onlay mesh implantation on the day of discharge (p = 0.010) and three (p = 0.009) and six (p = 0.023) months postoperatively. The existing evidence on prophylactic mesh augmentation in patients undergoing AAA-repair via midline laparotomy probably needs critical review. As the implementation of new RCTs is considered difficult due to the increasing number of endovascular AAA treated, registry studies could help to collect and evaluate data in cases of open AAA-repair. Comparisons between prophylactic mesh implantation and the small bite technique are also required. Trial registration: ClinicalTrials.gov Identifier: NCT01353443. Funding Sources: Aesculap AG, Tuttlingen, Germany.

Application of Color Doppler Ultrasound in the Clinical Diagnosis of Uterine Incision Infection

Objective: To observe the early changes of uterine incision defects after cesarean section by transvaginal color Doppler ultrasound, and to analyze the risk factors of their formation. Methods: A total of 181 women who underwent cesarean section from September 2016 to June 2018 and who underwent transvaginal ultrasound examination at 6 weeks, 3 months, and 6 months after birth were divided into two groups. (142 cases) and incision defect group (39 cases). The incision changes and the risk factors of incision defect in different periods of postpartum were analyzed. Results: Compared with the group with good incision healing, the length of the incision defect in the cesarean section at 6 months after delivery was shorter than that at 6 weeks after delivery (P &lt; 0.05). The results of non-conditional logistic regression showed that the number of cesarean sections increased and the number of operators was lower. Seniority, postoperative infection, posterior uterine position, and incision close to the cervix are risk factors for poor healing of uterine scars. Conclusion: As the postpartum time increases, the length of the cesarean section incision defect shortens; multiple cesarean sections, puerperal infections, posterior uterus, low incision position and inexperience of the operator are the risk factors for the formation of uterine incision defects and increase uterine scars. Risk of poor healing.

Lower Uterine Section Transverse Incision Defect and Ectopic in the Cesarean Section Scar: A Case Presentation and Review of The Literature

Lower Uterine Section Transverse Incision Defect and Ectopic in the Cesarean Section Scar: A Case Presentation and Review of The Literature

Clinical analysis of the preoperative condition and operative prognosis of post-cesarean section scar diverticulum: a case series.

Objectives Post-cesarean section scar diverticulum (PCSD) is a long-term sequela of cesarean section (CS). The aim of this study was to evaluate the clinical utility of PCSD scoring criteria, and also retrospectively investigate the efficacy and fertility of two different surgical methods in 304 patients with PCSD. Methods A total of 304 PCSD patients who underwent hysteroscopy or combined hysteroscopy and laparoscopy (referred to as laparoscopy) in our hospital from 2016 to 2018 were retrospectively analyzed. Preoperative condition was analyzed by the PCSD scoring criteria and its influencing factors were explored. The efficacy, its influencing factors and pregnancy success rate of the two different surgical methods on PCSD was also analyzed after 6- and 12-months follow-up. Results PCSD was more severe (high score) in patients who experienced caesarean section with one of the following conditions: age>30 years old, without medical indications or retroflexed uterus. The postoperative efficacy of patients subjected to hysteroscopy or laparoscopy was 81.25 and 89.47% (after 6 months), and 79.53 and 87.50% (after 12months), respectively. Hysteroscopic surgery was better for PCSD patients who had fewer CS and thicker residual muscle layer and worse for PCSD patients with a longer distance of incision defect to the end of the cervix. Postoperative fertilization showed that pregnancy success rate of patients subjected to hysteroscopy or laparoscopy was 56.2 and 50%, respectively. Conclusions The PCSD scoring is an effective method for assessing the severity of PCSD, and hysteroscopy and laparoscopy are effective modalities for PCSD. Hysteroscopy is also an option for patients with fertility needs.

Reduced Nuclease Activity of Apurinic/Apyrimidinic Endonuclease (APE1) Variants on Nucleosomes: IDENTIFICATION OF ACCESS RESIDUES

Non-coding apurinic/apyrimidinic (AP) sites are generated at high frequency in genomic DNA via spontaneous hydrolytic, damage-induced or enzyme-mediated base release. AP endonuclease 1 (APE1) is the predominant mammalian enzyme responsible for initiating removal of mutagenic and cytotoxic abasic lesions as part of the base excision repair (BER) pathway. We have examined here the ability of wild-type (WT) and a collection of variant/mutant APE1 proteins to cleave at an AP site within a nucleosome core particle. Our studies indicate that, in comparison to the WT protein and other variant/mutant enzymes, the incision activity of the tumor-associated variant R237C and the rare population variant G241R are uniquely hypersensitive to nucleosome complexes in the vicinity of the AP site. This defect appears to stem from an abnormal interaction of R237C and G241R with abasic DNA substrates, but is not simply due to a DNA binding defect, as the site-specific APE1 mutant Y128A, which displays markedly reduced AP-DNA complex stability, did not exhibit a similar hypersensitivity to nucleosome structures. Notably, this incision defect of R237C and G241R was observed on a pre-assembled DNA glycosylase·AP-DNA complex as well. Our results suggest that the BER enzyme, APE1, has acquired distinct surface residues that permit efficient processing of AP sites within the context of protein-DNA complexes independent of classic chromatin remodeling mechanisms.

Papilla Base Incision: An Evaluation of Post-Operative Healing of Interdental Papilla after Endodontic Surgery

Aims and objectives: The purpose of this study was to describe and evaluate a novel marginal incision technique –the papilla base incision, which preserves the integrity of the interdental papilla during and after endodontic surgery in cases where there is no evidence of marginal periodontitis. Methodology: Fifteen patients in general good health referred to the department of endodontics with periradicular pathology where endodontic surgery was indicated were selected for the study irrespective of age, sex and socioeconomic status. Results: The visual observation of the incisions at one month recall demonstrated one site with visible defects (grade 1), five sites with partially detectable incision defect (grade 2) and nine sites with perfect healing (grade 3). Conclusion: Papilla based incision is an excellent method of elevating the mucoperiosteal flap with excellent esthetics and without any postoperative loss of papilla height or gingival recession.

Five-year clinical performance of a HEMA-free one-step self-etch adhesive in noncarious cervical lesions

The objective of this randomized controlled trial was to evaluate the clinical performance of a 2-hydroxyethyl methacrylate (HEMA)-free one-step adhesive. Two hundred sixty-seven cervical lesions in 52 patients were restored with the composite Gradia Direct (GC), bonded with either the one-step self-etch adhesive G-Bond (GC) or the three-step etch-and-rinse adhesive Optibond FL (Kerr) in a random order. The restorations were evaluated for retention, marginal integrity, marginal discoloration, and caries occurrence after 5 years. Specific statistics were used to account for the clustered data (multiple restorations per patient). The clinical success rate for G-Bond (87.4 %) was not significantly different from that of Optibond FL (90.9 %). Both adhesives showed progressive marginal deterioration, but G-Bond exhibited more small enamel defects and marginal discoloration, and unlike previous recalls, several restorations failed because of deep microleakage. Large sclerotic lesions were a significant risk factor for retention loss with G-Bond. Irrespective of the adhesive, almost all restorations with retention loss were located in the lower jaw. After 5 years of clinical service, restorations bonded with the HEMA-free one-step adhesive did not need repair or replacement more often than those with the three-step etch-and-rinse adhesive, and both adhesives had a high retention rate (>90 %). There were indications that G-Bond did not (self-)etch enough in some clinical situations, as G-Bond exhibited more incisal defects and marginal discolorations, and sclerotic lesions were at higher risk of retention loss. The clinical performance of the HEMA-free one-step adhesive was clinically acceptable after 5 years.

Local Morphological Response of the Distal Femoral Articular–Epiphyseal Cartilage Complex of Young Foals to Surgical Stab Incision and Potential Relevance to Cartilage Injury and Repair in Children

Objective: Describe the local morphological response of the articular–epiphyseal cartilage complex to surgical stab incision in the distal femur of foals, with emphasis on the relationship between growth cartilage injury, enchondral ossification, and repair. Design: Nine foals were induced into general anesthesia at the age of 13 to 15 days. Four full-thickness stab incision defects were created in the cartilage on the lateral aspect of the lateral trochlear ridge of the left distal femur. Follow-up examination was carried out from 1 to 49 days postoperatively, including examination of intact bones, sawed slabs, and histological sections. Results: Incision defects filled with cells displaying fibroblast-, chondrocyte-, and osteoblast-like characteristics, potentially validating the rationale behind the drilling of stable juvenile osteochondritis dissecans lesions in children. Incisions induced necrosis within the cartilage on the margins at all depths of the defects. Sharp dissection may therefore be contraindicated in cartilage repair in young individuals. Incisions caused a focal delay in enchondral ossification in 2 foals, apparently related to the orientation of the incision defect relative to the direction of ossification. Defects became progressively surrounded by subchondral bone, in which granulation tissue containing clasts and foci of osteoblast-like cells was observed. Continued enchondral ossification was therefore likely to result in healing of uncomplicated defects to morphologically normal bone. Conclusions: Epiphyseal growth cartilage injury had the potential to exert a negative effect on enchondral ossification. Enchondral ossification exerted a beneficial effect on repair. This relationship warrants consideration in future studies of cartilage injury and repair within the articular–epiphyseal cartilage complex of all species.

Enamel defects of human primary dentition as virtual memory of early developmental events.

Background and aims The objectives of the present study were to investigate the prevalence and the position of enamel defects of primary teeth and hence to estimate the approximate time of an insult. Materials and methods 121 children aged 3 to 5 years were included in the study. The Modified Developmental De-fects of Enamel Index was used to diagnose and classify the defects. The defects were categorized as hypoplasia, hypocalcification or a combination of them. Each tooth was investigated for occlusal/incisal, middle, cervical, incisomiddle, cervicomiddle and complete crown defects. Results 55.37% of the children were affected by enamel defects, 23.96% being categorized as hypocalcification and 22.31% as hypoplasia. The enamel defects were more abundant in maxillary primary incisors and mandibular primary canines. Minimum involvement was seen in maxillary primary second molars and mandibular primary lateral incisors. The prevalence of cervical defects in maxillary primary incisors was significantly more than the middle or incisal defects (P < 0.05). The prevalence of incisal defects in mandibular primary incisors was significantly more than the middle or cervical defects (P < 0.05). Conclusion The results revealed a considerable number of enamel defects which are multiple, symmetric and chrono-logically accordant with the estimated neonatal line in primary teeth of healthy children.

A New Approach on Reconstruction of Frontonasal Encephalomeningocele Assisted With Medpor

The frontoethmoidal encephalomeningocele, which is a congenital brain herniation through skull defect at the frontoethmoidal region, is a common problem in Southeast Asia. Patients usually present with perinasal mass(es), and its pressure affects facial structures resulting to conditions such as telecanthus, medial canthal dystopia, long nose, and elevated medial eyebrows. Currently 1-stage surgical correction is widely accepted. Facial incision is routinely made for accessing the facial structures, removing the mass as well as resecting the covering skin which is usually expanded and redundant. Resultant facial scar is usually extensive and becomes a stigma of the disease even after a surgical correction. This study demonstrates the possibility of doing definitive surgery with minimal facial incision and bone defect reconstruction with the alloplastic material. In this study, we used the porous polyethylene implant for bone defect. This can be an alternative approach to autogenous reconstruction of frontoethmoidal encephalomeningocele.

Three‐year clinical effectiveness of a two‐step self‐etch adhesive in cervical lesions

A 3-yr randomized, controlled prospective study evaluated the clinical effectiveness of a mild two-step self-etch adhesive, Clearfil SE, in Class-V non-carious lesions. The hypothesis tested was that prior selective etching of enamel with phosphoric acid does not affect the 3-yr clinical performance of this adhesive. A total of 100 lesions in 29 patients were randomly restored in one or two pairs, according to two experimental protocols: (i) application of Clearfil SE according to the instructions of the manufacturer (C-SE non-etch); and (ii) similar application of Clearfil SE with prior etching of enamel cavity margins with phosphoric acid (C-SE etch). Clearfil AP-X was used as a restorative material. At 3 yr, 90% of the restorations were examined for retention, marginal integrity, marginal discoloration, caries recurrence, postoperative sensitivity, and preservation of tooth vitality. An excellent retention rate (100%) was noted after 3 yr of clinical functioning. Only one restoration of the C-SE etch group was clinically unacceptable owing to the presence of a severe cervical marginal defect. A pairwise comparison between both groups showed a significant difference only in the number of small marginal defects at the enamel side, which was higher in the C-SE non-etch group. These incisal defects were small and clinically irrelevant. Superficial marginal discoloration increased slightly in the C-SE non-etch group and was related to the higher frequency of small incisal marginal defects. In this latter group, localized marginal discoloration was observed significantly more in smokers. In conclusion, the clinical performance of the mild two-step self-etch adhesive, Clearfil SE, remained excellent after 3 yr of clinical functioning. Additional etching of the enamel cavity margins was not critical for its clinical performance.

Fanconi anemia, complementation group A, cells are defective in ability to produce incisions at sites of psoralen interstrand cross-links.

The hypersensitivity of Fanconi anemia, complementation group A, (FA-A) cells to agents which produce DNA interstrand cross-links correlates with a defect in their ability to repair this type of damage. In order to more clearly elucidate this repair defect, chromatin-associated protein extracts from FA-A cells were examined for ability to endonucleolytically produce incisions in DNA at sites of interstrand cross-links. A defined 140 bp DNA substrate was constructed with a single site-specific monoadduct or interstrand cross-link produced by 4,5',8-trimethylpsoralen (TMP) plus long wavelength (UVA) light. Our results show that FA-A cells are defective in ability to produce dual incisions in DNA at sites of interstrand cross-links. Specifically, there is defective incision on the 3'- and 5'-sides of both the furan and pyrone sides of the cross-link. This defect is corrected in FA-A cells transduced with a retroviral vector expressing FANCA cDNA. At the site of a TMP monoadduct, FA-A cells can introduce incisions on both the 3'- and 5'-sides of the furan side monoadduct, but are defective in ability to produce these incisions on the pyrone side monoadduct. These studies also indicate that XPF is involved in production of the 5' incision by the normal extracts on these substrates. These results correlate with our previous work, which showed that FA-A cells are mainly defective in ability to repair psoralen interstrand cross-links with a lesser defect in ability to repair psoralen monoadducts. This defect in endonucleolytic incision at sites of TMP interstrand cross-links could be related to reduced levels of non-erythroid alpha spectrin (alphaSpIISigma*) in the extracts from FA-A cells. alphaSpIISigma* could act as a scaffold to align proteins involved in cross-link repair and enhance their interactions; a deficiency in alphaSpIISigma* could thus lead to reduced efficiency of repair and the decreased levels of incisions we observe at sites of interstrand cross-links in FA-A cells.

A murine AP-endonuclease gene-targeted deficiency with post-implantation embryonic progression and ionizing radiation sensitivity

Apurinic/apyrimidinic endonuclease (here designated APE/REF) carries out repair incision at abasic or single-strand break damages in mammals. This multifunctional protein also has putative role(s) as a cysteine `reducing factor' (REF) in cell-stress transcriptional responses. To assess the significance of APE/REF for embryonic teratogenesis we constructed a more precisely targeted Ape/Ref-deficient genotype in mice. Ape/Ref gene replacement in ES cells eliminated the potential of APE/REF protein synthesis while retaining the Ape/Ref bi-directional promoter that avoided potential inactivation of an upstream gene. Chimeric animals crossed into Tac:N:NIHS-BC produced germline transmission. Homozygous null Ape/Ref-embryos exhibited successful implantation and nearly normal developmental progression until embryonic day 7.5 followed by morphogenetic failure and adsorption of embryos by day 9.5. We characterized the cellular events proceeding to embryonic lethality and examined ionizing radiation sensitivity of pre-implantation Ape/Ref-null embryos. After intermating of heterozygotes, Mendelian numbers of putative Ape/Ref-null progeny embryos at day 6.5 displayed a several-fold elevation of pycnotic, fragmenting cell nuclei within the embryo proper—the epiblast. Increased cell-nucleus degeneration occurred within epiblast cells while mitosis continued and before obvious morphogenetic disruption. Mitogenic response to epiblast cell death, if any, was ineffective for replacement of lost cells. Extra-embryonic yolk sac, a trophectoderm derived lineage retained normal appearance to day 9. Explanted homozygous Ape/Ref-null blastocysts displayed increased sensitivity to γ-irradiation, most likely a manifestation of APE/REF incision defect. Our study establishes that this new Ape/Ref deficiency genotype is definitely capable of post-implantation developmental progression to the onset of gastrulation. Function(s) of APE/REF in base damage incision and also conceivably in mitogenic responses towards epiblast cell death are critical for transit through the gastrulation stage of embryonic growth and development.

Mechanism of open complex and dual incision formation by human nucleotide excision repair factors.

During nucleotide excision repair in human cells, a damaged DNA strand is cleaved by two endonucleases, XPG on the 3' side of the lesion and ERCC1-XPF on the 5' side. These structure-specific enzymes act at junctions between duplex and single-stranded DNA. ATP-dependent formation of an open DNA structure of approximately 25 nt around the adduct precedes this dual incision. We investigated the mechanism of open complex formation and find that mutations in XPB or XPD, the DNA helicase subunits of the transcription and repair factor TFIIH, can completely prevent opening and dual incision in cell-free extracts. A deficiency in XPC protein also prevents opening. The absence of RPA, XPA or XPG activities leads to an intermediate level of strand separation. In contrast, XPF or ERCC1-defective extracts open normally and generate a 3' incision, but fail to form the 5' incision. This same repair defect was observed in extracts from human xeroderma pigmentosum cells with an alteration in the C-terminal domain of XPB, suggesting that XPB has an additional role in facilitating 5' incision by ERCC1-XPF nuclease. These data support a mechanism in which TFIIH-associated helicase activity and XPC protein catalyze initial formation of the key open intermediate, with full extension to the cleavage sites promoted by the other core nucleotide excision repair factors. Opening is followed by dual incision, with the 3' cleavage made first.

UV-C sensitivity of unstimulated and stimulated human lymphocytes from normal and xeroderma pigmentosum donors in the comet assay: A potential diagnostic technique

We have studied incision-break formation in unstimulated and stimulated populations of human T-lymphocytes using the comet (single-cell microgel electrophoresis) assay. The frequency of strand breaks 1 h after UV-irradiation appears to be far greater in unstimulated than in stimulated lymphocytes from normal donors and the excess of strand breaks was observed for a far longer time after irradiation. This result corroborates the greater sensitivity to UV-C irradiation observed in a colony-forming assay but suggests that the defect may relate to a defect in strand rejoining rather than a defect in incision. Few strand breaks were seen in either unstimulated or stimulated lymphocytes of four xeroderma pigmentosum donors, suggesting that the method may offer a rapid diagnostic assay for XP.

YeastRAD14 and human xeroderma pigmentosum group A DNA-repair genes encode homologous proteins

Xeroderma pigmentosum (XP), a human autosomal recessive disorder, is characterized by extreme sensitivity to sunlight and high incidence of skin cancers. XP cells are defective in the incision step of excision repair of DNA damaged by ultraviolet light. Cell fusion studies have defined seven XP complementation groups, XP-A to XP-G. Similar genetic complexity of excision repair is observed in the yeast Saccharomyces cerevisiae. Mutations in any one of five yeast genes, RAD1, RAD2, RAD3, RAD4, and RAD10, cause a total defect in incision and an extreme sensitivity to ultraviolet light. Here we report the characterization of the yeast RAD14 gene. The available rad14 point mutant is only moderately ultraviolet-sensitive, and it performs a substantial amount of incision of damaged DNA. Our studies with the rad14 deletion (delta) mutation indicate an absolute requirement of RAD14 in incision. RAD14 encodes a highly hydrophilic protein of 247 amino acids containing zinc-finger motifs, and it is similar to the protein encoded by the human XPAC gene that complements XP group A cell lines.

Complementation of the xeroderma pigmentosum DNA repair synthesis defect withEscherichia coliUvrABC proteins in a cell-free system

A newly developed cell-free system was used to study DNA repair synthesis carried out by extracts from human cell lines in vitro. Extracts from a normal human lymphoid cell line and from cell lines established from individuals with hereditary dysplastic nevus syndrome perform damage-dependent repair synthesis in plasmid DNA treated with cis- or trans-diamminedichloro-platinum(II) or irradiated with ultraviolet light. Cell extracts of xeroderma pigmentosum origin (complementation groups A, C, D, and G) are deficient in DNA repair synthesis. When damaged plasmid DNA was pretreated with purified Escherichia coli UvrABC proteins, xeroderma pigmentosum cell extracts were able to carry out DNA repair synthesis. The ability of E. coli UvrABC proteins to complement xeroderma pigmentosum cell extracts indicates that the extracts are deficient in incision, but can carry out later steps of repair. Thus the in vitro system provides results that are in agreement with the incision defect found from studies of xeroderma pigmentosum cells.