Common inflammatory markers in the screening of knee arthroprosthesis infections

Aim To evaluate the sensitivity and specificity of serum C-reactive protein (CRP) in early and late total knee arthroplasty (TKA) infections. Methods Blood tests to determine CRP levels (cut-off 10 mg/L)were conducted before surgery, at 1st day, 7th day and 15th day after surgery and at 1, 3, 6,12, 24 and 36 months. Patients had routine follow-up visits and radiological evaluations at 14 days and at 1, 3, 6, 12, 24 and 36 months. Infections were recorded and classified according to Widmer classification. The χ2 test or Fisher (in subgroups smaller than 10 patients) exact test was used to compare categorical variables. The statistical significance was set at p <0.05. Results A total of 19 infections were diagnosed during the followup. According to Widmer, five were classified as early post-operative and 14 as late chronic. All patients with early infections had suspected symptoms such as fever, swelling and pain. During the first month, 59 patients who had high CRP level but negative microbiological culture were considered as false positive representing a CRP sensitivity of 80% and a specificity of 67.6%. Fourteen patients had late chronic infection. Conclusion This study suggests that a synovial fluid aspiration should be performed in patients with persistent inflammation symptoms with or without radiographic signs of loosening. Moreover, it recommends the use of different serum and synovial tests for periprosthetic joint infection (PJI) diagnosis.

Platet Rich Plasma or Hyperbaric Oxygen Therapy as callus accellerator in aseptic tibial non union. Evaluate of outcomes

Background and aim of the work:

The incidence of long bone non-unions has been estimated to range between 5-10%. Nonunion of fracture is a delayed complication of fracture. A large bone resection, associated with Ilizarov’s osteo-distraction technique, is commonly used in these cases. The war experience was very important for dealing with these injuries. The purpose of this study is to report whether the use of Platelet Rich of Plasma(PRP) or Hyperbric Oxygen Therapy(HOT) as an adjuvant to the osteogenic distraction of Ilizarov with respect to the classical method has advantages.

Methods:

From 183 tibial non union, we enrolled 50 patients suffering by Type B according ASAMI non union classification. We divided the patients into two groups. The first group was a retrospective group of patient treated by Ilizarov Tecnique plus PRP. Instead the second group, patients were treated by Ilizarov Tecnique associated with HOT. The chosen criteria to evaluate the two groups during the clinical and radiological follow-up were: the complication after the surgery in the two groups; the duration of surgery; the objective quality Bone results and functional results were evaluated according to ASAMI classification while the subjective quality of life correlated with Ilizarov frame function by the Short Form 12 Health Survey (SF-12); The correlation between bone regenerate/bone healing and X-rays. The evaluation endpoint was set at 12 months from the remotion of Ilizarov’s frame for both groups.

Results:

In comparing the complications of the two populations, there were a significant statistically difference(p<0.05) in the local skin inflammation and Dockin Point Skin retraction for HOT group while in refracture p<0.05 was for group PRP. From the SF-12 we discovered not statistically differences p<0.05. The average correlation between Bone Regenerate-Bone Healing/ X-rays is absolutely in the PRP as in the HOT, p>0.05. The average Time for remove Ilizarov’s Frame in months was 15.37(±7.34; range 9–32) in PRP while in HOT was15.22(± 7.83; range 9–31), p>0.05.

Conclusions:

From our study we can conclude that the association of HOT and PRP with the Ilizarov technique does not improve the functional outcomes but allows a more rapid healing of the regenerated bone and therefore an early removal of the device and a corresponding improvement in the quality of life. (www.actabiomedica.it)

Reliability of S.A.R.A. (sterilization and reimplantation autograft) technique in long bone open fractures

The reimplantation of small or large extruded bone segments is one of the most complex clinical management scenarios in the treatment of open fractures. No consensus exists regarding the efficiency of this technique. The aim of the study was to analyse the clinical and radiological outcomes of Sterilization and Reimplantation Autograft (S.A.R.A.) technique in open fractures. Therefore, fifteen skeletally mature patients with Gustilo-Anderson -IIIB type fractures treated with autograft reimplantation, were included in this study. The sample size was divided in two groups: patients with a loss of small segments (Group A - less than 5 cm) and those with large segments (Group B - greater than 5 cm). Eight patients belonged to Group A and seven to Group B. The treatment of contaminated bone may be performed by the following protocols: saline rinse, povidone-iodine scrub and saline rinse, retain periosteum, immersion in antibiotic solution (clindamycin and gentamicin and metronidazole), washing with physiological solution, acute reimplantation in Group A or reimplantation after 21 days in Group B after a bone freezing at -80°C. The Radiographic Union Score (RUS), pain visual analogic score (VAS), patient satisfaction and return to work were assessed at a mean follow-up of 24 months. No cases of superficial or deep infection were reported at 2-year follow-up. The fractures achieved a complete union in 14 patients; one patient belonging to Group A had a malabsorption of the replanted bone. Furthermore, povidone-iodine scrub, antibiotic solution immersion, and washing with physiological solution preserved the articular surface morphology. This study suggests that reimplantation of extruded short or long segments may represent a reliable alternative to amputation in open long bone fractures. Further studies are needed to define the most efficient technique for sterilizing the bone autograft to reduce the complication rate.

Bone grafiting combined with Sauvé-Kapandji Procedures for the treatment of aseptic distal radius non-union

Distal radius fractures are the most common type of upper limb fractures in adults. Non-union after distal radius fracture is rare, serious and unpredictable. The aim of our paper is to analyse the clinical and radiological outcomes of bone grafting and Sauvé-Kapandji Procedures for the treatment of aseptic distal radius non-union. We enrolled 13 patients with distal radius aseptic non-union. The following parameters were evaluated: The surgical time, elbow, forearm and wrist range of motion, the subjective quality of life and the wrist function measured by Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH), Pain Visual Analogic Score (VAS) and the complication rate. Bone union was measured using the radiographic union score as described by Radiographic Union Score (RUS). The evaluation endpoint was set at 24 months after surgery. All patients achieved fracture union. Grip strength improved by 12.4 kg. There was also improvement in wrist flexion, in wrist extension, and forearm pronosupination. These ranges of motion and grip strength improvements were statistically significant. Only 6 patients returned to full activity. This surgical technique represents a reliable alternative for treatment of distal radius aseptic non-unions. Further studies are needed to assess the long-term clinical results of this surgical procedure.

Grafting and fixation after aseptic non-union of the humeral shaft: A case series

PURPOSE

Non-unions after humeral shaft fractures are seen frequently in clinical practice at about 2-10% after conservative management and 30% after surgical treatment. Non-union, displacement of structures and fixation failure can be hazardous complications. The purpose of our study was to evaluate the outcomes of an on-lay bone graft strut construction with bone chips as grafting augmentation in the management of aseptic non-unions of the humeral shaft.

METHODS

From 124 eligible patients with a humeral shaft non-union, we included 48 patients. In all cases an anterolateral humeral approach was used, with an on-lay bone graft using an allograft strut construction and with bone substitute augmentation in the non-union gap. To assess the bone healing on radiographs, we used the non-union scoring system according to Whelan. Patients were followed with objective and subjective scores.

RESULTS

In all 48 patients we achieved full bone healing without major complications. The average period of union was 124 days. In 40 cases after healing the alignment was neutral, valgus deformation occurred in 6 cases a varus deformation in 2 cases. At twelve months after surgery, all patients recovered with satisfactory range of motion of shoulder and elbow and a good quality of life, without any radial nerve palsies or other major complications.

CONCLUSION

Given the satisfactory results of full bone healing, recovery of the range of motion and the lack of major complications as seen in this study, we find that plating with supporting allograft as a good choice of treatment in the cases of aseptic non-union of the humeral shaft.

A new plate design to treat displaced 3-4 parts proximal humeral fractures in comparison to the most tested and used plate: clinical and radiographic study

Aim Proximal humeral fractures are common and most complex patterns currently represent a challenge for surgeons. Difficulties in obtaining good anatomical reduction (particularly of great tuberosity) often lead to unsatisfactory results; choices often fall onto prosthesis implantation against fixation options. The aim of this study was to compare a new design of proximal humeral plate with the most used plates in the treatment of these injures by analysing outcomes and complications. Methods Two hundred patients with proximal 3 or 4 parts humeral fracture were enrolled (Neer 3-4). First group treated with PGR Plate composed of 98 patients. Second group treated with Philos Plate composed of 102 patients. Evaluation criteria were Non-Union Scoring System, duration of surgery, complications, objective quality of life and elbow function (Constant Shoulder Score), subjective quality of life and elbow function (Oxford Shoulder Score), post-op radiographs, centrum collum diaphyseal angle. Evaluation endpoint was 12 months. Results There was no statistically significant difference between the groups with regard to the selected evaluation parameters. Achievement of good shoulder range of motion and ability to perform normal daily living activities was obtained in both groups. The PGR had a positive impact on treatment results of varuspattern of proximal humeral fractures. Conclusions The PGR allowed good clinical and radiographic results in the treatment of proximal humeral fractures, comparable to those obtained with Philos. Also, PGR had the advantage to aid and keep the anatomical reduction of patterns of fracture involving the greater tuberosity.

Challenges in the management of floating knee injuries: Results of treatment and outcomes of 224 consecutive cases in 10 years

INTRODUCTION

Floating knee is a flail knee joint resulting from fractures of the shafts or adjacent metaphyses of the femur and the ipsilateral tibia. It is usually associated with several complications and mortality. This study was designed to present our experience with the treatment of this injury.

MATERIAL AND METHOD

This study was performed between January 2004 and December 2014. 224 cases of floating knee injuries gathered from the 34,480 lower extremities trauma files were studied, and the target information recorded. The injuries most frequently occurred in subjects between 16 and 35 years of age (60.71%), and in male subjects (85.71%). The most frequent mechanism of injury was traffic accident (92.85%). External fixation was the common type of treatment (82.14%) in emergency or as a definitive treatment. The treatment was performed within 24 h of the trauma. We performed a 36-month follow up with clinical examination, radiographs, assessing the complications, and using the Modified Cincinnati Rating System Questionnaire (MCRSQ) and the Karlström/Olerud Score (KOS) to evaluate the progression of the outcomes.

RESULTS

Early complications included 8 cases of compartment syndrome, 60 open fractures and 24 partially amputated limbs. A total amputation was performed in 3 patients. The most common late complication was heterotopic calcifications of the knee (n = 68, 30.6%). Good scores for MCRSQ and KOS were obtained only after patients were sent to a reference center for knee surgery.

CONCLUSIONS

Our experience revealed that the complication rate associated with floatingknee injuries remains high, regardless of the performed treatment. Surgeons should focus on reducing complications while treating these severe injuries.

The Advantages of Type III Scaphoid Nonunion Advanced Collapse (SNAC) Treatment With Partial Carpal Arthrodesis in the Dominant Hand: Results of 5-year Follow-up

Introduction:

The SNAC wrist (Scaphoid nonunion advanced collapse) is one of the complications following scaphoid fractures treated conservatively and one of the causes of wrist arthritis that the hand surgeon has to face most frequently. In these cases surgical management is usually warranted.

Materials and Methods:

In the set time frame of 6 years we treated 15 SNAC wrist cases. On average patients underwent surgery five years after the trauma. All patients were treated via dorsal incision with partial carpal arthrodesis and total scaphoidectomy, associated with denervation of the posterior interosseous nerves. A plaster cast was applied to all patients for 3 weeks postoperatively. In the preoperative stage, X-rays of the healthy contralateral limb were taken for the measurement of the normal radiocarpal joint space. Clinical and radiographic follow-ups were conducted at 1,3, 6 and 12 months from the trauma; then every 12 months. Criteria for the evaluation of patients: visual analog pain scale (VAS), average time of radiographic fusion of wrist bones, Active Range of Wrist Motion (WAROM), subjective Mayo Wrist Score (MWS) and The Short Form ( 36) Health Survey (SF-36), return to the main tasks and complications. The evaluation endpoint was set at 60 months. Average time of surgery: 48.3 minutes. Average time of arthrodesis consolidation: 67.8 days. The VAS and WAROM showed a gradual improvement in seriated controls, returning to values almost identical to pre-trauma at a 5-year follow-up. By this time, the MWS and SF-36 scores were similar to pre-trauma. On average, the return to pre-injury daily activities occurred in 12.5 months after surgery. There were no complications.

Conclusions:

The partial carpal arthrodesis is a safe and effective procedure for the treatment of SNAC wrist cases. Our results show a progressive and significant improvement in ROM, VAS and great satisfaction from the patient.

WITHDRAWN: Challenges in the management of floating knee injuries: Results of treatment and outcomes of 224 consecutive cases in 10 years

The Publisher regrets that this article is an accidental duplication of an article that has already been published in Injury, 50(2) (2019) 453–461, https://doi.org/https://doi.org/10.1016/j.injury.2018.12.009. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Efficacy of the "Salento technique", a modified two-incision approach in distal biceps brachii tendon repair. Surgical description and outcomes analysis

INTRODUCTION

The biceps brachii lesion needs to be treated surgically. A modified two incisions technique is proposed and reviewed. Material and Methods: All patients were treated with the same technique. The outcomes were measured with the Quick-DASH Score (QDS), and the Mayo Elbow Performance Score (MEPS). Postoperative complications and distal biceps tendon strength were registered also.

RESULTS

At one year from the trauma, the QDS and the MEPS were excellent in all patients. 72.97% fully recovered and returned to work after 6 months from the trauma.

DISCUSSION

This technique, thanks to its preservation of anatomical structures, provides great outcomes.

Effect of trochleocapitellar index on adult patient-reported outcomes after noncomminuted intra-articular distal humeral fractures

BACKGROUND

Anatomic surgical reduction of intra-articular fractures of the distal humerus is important to achieve the best long-term outcomes and prevent post-traumatic arthritis. In this study we compared the radiographic reduction using the trochleocapitellar index. We also correlated the trochleocapitellar index to the functional outcomes next to the comparison of the triceps brachii lifting approach and olecranon osteotomy approach, 2 common approaches for distal humeral fractures.

METHODS

From January 2006 to June 2016, patients with elbow fractures were registered in 4 centers. The trochleocapitellar index, a ratio between the angle of the capitellum and the trochlea to the midline of the distal humerus on anterior-posterior radiographs, was calculated for included patients. Functional outcomes were measured using the Oxford Elbow Score and the Mayo Elbow Performance Score. Bone healing was measured using radiographic union scoring.

RESULTS

There were 86 patients enrolled: 46 in the olecranon osteotomy group and 40 in the triceps lifting group. Functional outcomes and bone healing did not differ between the approaches. Functional results had a medium correlation with the trochleocapitellar index, which did not differ between the 2 approaches (olecranon osteotomy group, κ = 0.56; triceps lifting group, κ = 0.57; P = .7932).

CONCLUSIONS

The trochleocapitellar index has a moderate predictive value on the functional results after 12 months after open reduction and internal fixation of intra-articular distal humeral factures. There is no difference in reduction, as measured by trochlear index and functional outcome scores, between the olecranon osteotomy approach and the triceps brachii lifting approach groups.

Grafting and fixation of proximal humeral aseptic non union: a prospective case series

Background

Fractures of the proximal part of the humerus represent almost 4-5% of all fractures. The rate of non union is estimated to be 1.1 to 10%. Non union, displacement, and fixation failure can be hazardous complications for these injuries. The purpose of our study was to evaluate the outcomes of plate and bone strut allograft with bone chips grafting augmentation in the management of proximal humeral aseptic non union.

Methods

We treated 16 aseptic non union proximal humeral fractures by the medial humeral shaft bone strut allograft and lateral plate and screws with bone chips grafting. The patients' ages were between 55 and 70 years. The chosen criteria to evaluate the group during the clinical and radiological follow-up were the quality of life measured by The Short Form (12) Health Survey (SF-12), shoulder function and related quality of life measured by the Constant Shoulder Score (CSS) compared with healthy side, bone healing measured by X-rays, and postoperative complications. The follow-up was perfor med with clinical and radiographic controls at 1, 3, 6 and 12 months. Surgical time and international units of red blood cells transfused were also calculated. The evaluation endpoint was set at 12 months.

Results

The X-rays bone healing occurred in our group on average of 126.4 days after surgery. The surgical time and blood loss were consistent with standard surgical procedures. The quality of life and functional recovery were excellent after plate and bone strut allograft.

Conclusions

Surgical techniques that increase mechanical stability, while incorporating bone biology, are effective aids for treating problematic fractural patterns.

The challenge of nonunion after osteosynthesis of the clavicle: is it a biomechanical or infection problem?

Introduction

The nonunion rate has been reported between 0.1% and 15%. There are also several predisposing factors for the onset of complications: general factors connected with the patient and specific factors related to the fracture site. The purpose of our study is to review the etiology of nonunion of the clavicle in its atrophic form and investigate the outcomes of the revision treatment in a single step.

Materials and methods

Retrospective study on 71 patients suffering from nonunions due to the following treatments: conservative in 13 patients; plate fixation in 12; closed reduction and fixation with K-wire in 24; open reduction and fixation with K-wire. All patients were operated on in beach chair position and classic approach to the clavicle by incising the previous surgical scar. The clinical and radiographic criteria for evaluating the outcomes were: the Short Form (12) Health Survey (SF-12), the Constant Shoulder Score (CSS) and the Disability Disabilities of the Arm, Shoulder and Score (DASH) and radiographic Union Score (RUS) for bone healing. The evaluation endpoint was set at 12 months.

Results

Blood and culture tests showed 22 infected nonunions and 49 atrophic or oligoatrophic. In only 10 cases, before surgery, the inflammatory markers were positive. The isolated microorganisms were resistant to common antibiotics. In 70 out of 71 cases, plates and screws on the upper side and fibula allogenic splints at the bottom, associated with cancellous bone grafts taken from the patients' iliac crests, were implanted. In one case, however, it was decided to implant the plate on the front edge of the clavicle and the fibula allogeneic splint on the posterior margin, also associated with a cancellous bone graft taken from the patient's iliac crest. The radiographic bone healing was observed in 107.8 (range 82-160) days for the aseptic nonunions, while in 118.4 (range 82-203) days for the septic ones. The non-healing case was a serious failure that led to asubtotal excision of the clavicle.

Conclusions

The importance of classification and study of nonunions are essential to achieve positive outcomes. The guiding principle of our work is that aseptic nonunions heal in the operating room, while infected nonunions can be challenged and defeated on the operating table. Restoring the correct length of the clavicle interconnection between the sternum and the shoulder cingulum is indispensable to avoid functional deficits of the upper limb. The fibula splint and the tricorticale bone graft have both mechanical and strong biological values to quickly heal the nonunion. The return to pre-injury quality of life has to be our main goal.

The challenge of non-union in subtrochanteric fractures with breakage of intramedullary nail: evaluation of outcomes in surgery revision with angled blade plate and allograft bone strut

PURPOSE

Subtrochanteric fractures have a bimodal age distribution. They usually require open reduction and internal fixation. Closed reduction and intramedullary nail fixation rate are increased for this type of fracture. As a result, the hardware breakage and non-union rate is high among such patients. Our purpose is to evaluate the outcomes of the role of blade plate and bone strut allograft in the management of subtrochanteric non-union by femoral nailing.

MATERIALS AND METHODS

We reported a group of 22 patients with subtrochanteric non-union, associated with breakage of the intramedullary nail with medial femoral allograft bone and lateral blade plate and wire (PS) s; and a group of 13 patients with subtrochanteric non-union, associated with breakage of the intramedullary nail treated with lateral blade plate and screws (CG). The chosen criteria to evaluate the two group during the clinical and radiological follow-up were the quality of life, measured by The Short Form (12) Health Survey (SF-12), the hip function and quality of life related to it, measured by the Harris Hip Score (HHS), bone healing, measured by Radiographic Union Score (RUS) by XR and CT at 1 year after the surgery, and postoperative complications. The evaluation endpoint was set at 12 months.

RESULTS

The Bone healing measured by RUS occurred and also the full recovery before the first trauma measured by SF-12 and HHS are better in PS group. We only had three unimportant complications in PS while four breakage hardware in CG.

CONCLUSION

We conclude that in complicated non-unions, the use of blade plate and bone strut allograft has a definite positive role in the management of such cases.

Percutaneous screws CT guided to fix sacroiliac joint in tile C pelvic injury. Outcomes at 5 years of follow-up

Introduction: The treatment of the sacroiliac joint (SIJ) vertical instability is a matter of current discussions and remains controversial. The aim of our study is the evaluation of the surgical management of SIJ vertical instability involving the use of cannulated screws introduced under CT guidance and local anesthesia.

Materials and methods: In the set time frame of 7 years, 96 poly-trauma patients with Tile's type C fracture of the pelvis with vertical instability of the SIJ were treated. The average distance between the two stumps was 73.4 mm (range: 43–100 mm). All patients were treated with anterior stabilization and subsequent stabilization with cannulated screws (Asnis^® Stryker^® 6 mm, an average length of 70 mm; range from 55 to 85 mm) of the sacroiliac fracture. The clinical and radiological follow-up was performed with follow-up plain radiograph and Majeed score (from 1 to 60 months after injury).

Results: The consolidation of pelvic fractures was obtained after an average of 63 days. The average Majeed score was as follows: 96 points at 1 month, 84 points at 3 months, 62 points at 6 months, 44 points at 12 months, 42 points at 24 months, 32 points at 36 months, 28 points at 48 months and 28 points at 60 months. Complications were as follows: not fatal deep vein thrombosis in five cases, skin infection at the entry point of the screws in six cases, screw breakage in one case and loosening of the screws in one case. Radiological evidence of fracture consolidation was achieved on average at 63 days. Forty-seven patients managed to get back to their pre-trauma employment at the end of the convalescence period.

Conclusions: Our results suggest that the stabilization of SI Tile type C fracture/dislocations with CT-guided percutaneous cannulated screws is a valid and feasible management option and associated with a low complication rate.

Percutaneous hallux valgus surgery: strengths and weakness in our clinical experience

BACKGROUND AND AIM OF THE WORK

The Reverdin-Isham percutaneous osteotomy is indicated in the treatment of mild to moderate hallux valgus deformity. The aim of the work is the evaluation of the technique itself as a possible future landmark in the hallux valgus treatment.

METHODS

Between January 2010 and January 2011 we have performed 138 percutaneous osteotomies. The patients were assessed with a clinical and radiological control after a median five months follow up. The score proposed by the American Orthopaedic Foot and Ankle Society was used for the clinical evaluation.

RESULTS

The average score has improved from a preoperative median of 45 points to a postoperative median of 91 points. The technique has been largely accepted by the patients because of the speed of the procedure itself, the minimal invasiveness, the short pain and the immediate functional recovery.

CONCLUSIONS

The results we have obtained with the Reverdin-Isham procedure have confirmed that this technique is a valid alternative to other percutaneous techniques and open surgical procedures. However the technique is not simple, it needs the strict indications observance and it needs a steep learning curve, those are features that impose further future studies.

Orbital metastasis associated with primary breast carcinoma in a man detected during peribulbar anesthesia for cataract surgery

PURPOSE

A case of orbital infiltration by breast carcinoma in a male patient causing mild enophthalmos and subcutaneous mass detected accidentally during peribulbar anesthesia for cataract surgery is discussed.

METHODS

The authors report a case of a 65-year-old man who came to the Ophthalmology Department for cataract surgery. During the presurgery peribulbar injection, a hard palpable mass located under the inferior left eyelid was noted, together with mild enophthalmos. A historical clinical screening revealed that 5 years previously the patient had undergone a right radical mastectomy to treat a ductal carcinoma of the breast.

RESULTS

The patient underwent an incisional biopsy of the orbital mass that confirmed the clinical hypothesis of a metastasis.

DISCUSSION

This case highlights the importance of the collection and screening of detailed clinical information on the patient before every ophthalmic operation including cataract surgery. The occurrence of progressive enophthalmos can represent an unusual symptom of orbital metastasis, commonly presenting with proptosis and diplopia.

Hypersensitivity to camptothecin in MSH2 deficient cells is correlated with a role for MSH2 protein in recombinational repair

DNA mismatch repair (MMR) corrects DNA polymerase insertion errors that have escaped proofreading in order to avoid the accumulation of deleterious mutations. While the role of MMR in the correction of replication errors is well established, its involvement in the processing of DNA damage induced by chemical and physical agents is less clear. A role for some of the MMR proteins, such as MSH2, in the repair of double strand break (DSBs) through recombination has also been envisaged. Why MMR- deficient cells are sensitive to agents causing replication fork stalling and thus DSBs remains unclear. To verify a possible role of MSH2 in homologous recombinational repair, we have treated cells from knockout mice for the MSH2 gene and mouse colorectal carcinoma cells also defective for MSH2 with different doses of camptothecin, an agent known to interfere with DNA replication. In the absence of MSH2, we found a reduced survival rate accompanied by higher levels of chromosomal damage and SCE induction. Furthermore, MSH2(-/-) cells displayed an elevated spontaneous RAD51 focus-forming activity and a higher induction of RAD51 foci following camptothecin treatment. Thus, the absence of MSH2 could result in both spontaneous DNA damage and uncontrolled recombination events leading to the observed higher yield of chromosomal damage and the higher induction of RAD51 foci following CPT treatment. Therefore, our results suggest an involvement of MSH2 in the early events leading to correct RAD51 relocalization after the formation of DSBs specifically produced at the blocked replication fork.

Werner's syndrome protein is required for correct recovery after replication arrest and DNA damage induced in S-phase of cell cycle

Werner's syndrome (WS) is a rare autosomal recessive disorder that arises as a consequence of mutations in a gene coding for a protein that is a member of RecQ family of DNA helicases, WRN. The cellular function of WRN is still unclear, but on the basis of the cellular phenotypes of WS and of RecQ yeast mutants, its possible role in controlling recombination and/or in maintenance of genomic integrity during S-phase has been envisaged. With the use of two drugs, camptothecin and hydroxyurea, which produce replication-associated DNA damage and/or inhibit replication fork progression, we find that WS cells have a slower rate of repair associated with DNA damage induced in the S-phase and a reduced induction of RAD51 foci. As a consequence, WS cells undergo apoptotic cell death more than normal cells, even if they arrest and resume DNA synthesis at an apparently normal rate. Furthermore, we report that WS cells show a higher background level of DNA strand breaks and an elevated spontaneous induction of RAD51 foci. Our findings support the hypothesis that WRN could be involved in the correct resolution of recombinational intermediates that arise from replication arrest due to either DNA damage or replication fork collapse.

Investigation of G2-phase chromosomal radiosensitivity in hereditary non-polyposis colorectal cancer cells

PURPOSE

To investigate whether cells from hereditary nonpolyposis colorectal cancer (HNPCC) patients, a genetic condition characterized by constitutional mutations in DNA mismatch repair genes and associated with predisposition to colorectal carcinoma (CRC), could present a higher G2 chromosomal radiosensitivity. It is generally hypothesized that cancer predisposition in HNPCC is associated with the loss of the wild-type allele in somatic cells, resulting in defective DNA mismatch repair but, to date, no data on G2 radiosensitivity have been reported for HNPCC.

MATERIALS AND METHODS

Lymphoblastoid cell lines derived from six HNPCC patients heterozygous for MLH1, one HNPCC patient carrying a mutant MSH2 allele and three healthy controls were treated with 50 cGy of X-rays and sampled at various harvesting times, monitoring cell-cycle progression by 5-bromo-2-deoxyuridine (BrdUrd) incorporation in order to analyse chromosomal damage in the homogeneous G2 population.

RESULTS

There were no differences between lymphoblasts derived from patients in the frequency of G2 chromosomal aberrations induced by X-rays when compared with control cell lines. However, despite the absence of G2 radiosensitivity in HNPCC cells, lymphoblasts from patients heterozygous for MLH1 mutations showed a higher induction of chromatid exchanges.

CONCLUSIONS

The observed possible incorrect rejoining of double-strand breaks in MLH1 heterozygotes would be an additional and important factor contributing to loss of heterozygosity in HNPCC patients.

Predisposition to cancer and radiosensitivity

Many cancer-prone diseases have been shown to be radiosensitive. The radiosensitivity has been attributed to pitfalls in the mechanisms of repair of induced DNA lesions or to an impaired cell cycle checkpoint response. Although discrepancies exist in the results obtained by various authors on the radiosensitivity of individuals affected by the same disease, these can be attributed to the large variability observed already in the response to radiation of normal individuals. To date three test are commonly used to assess radiosensitivity in human cells: survival, micronucleous and G2 chromosomal assay. The three tests may be performed using either fibroblasts or peripheral blood lymphocytes and all the three tests share large interindividual variability. In this regard a new approach to the G2 chromosomal assay which takes into account the eventual differences in cell cycle progression among individuals has been developed. This new approach is based on the analysis of G2 homogeneous cell populations. Cells irradiated are immediately challenged with medium containing bromodeoxyuridine (BrdUrd). Then cells are sampled at different post-irradiation times and BrdUrd incorporation detected on metaphases spread and the scoring is done only at time points showing similar incidence of labelled cells among the different donors. Using this approach it has been possible to reduce the interindividual variability of the G2 chromosomal assay.

Werner's syndrome cell lines are hypersensitive to camptothecin-induced chromosomal damage

Werner's syndrome (WS) is a recessive human genetic disorder associated with an elevated incidence of many types of cancer. The WS gene product, WRNp, belongs to the RecQ family of DNA helicases and is required for the maintenance of genomic stability in human cells. A possible interaction between helicases and topoisomerases that could co-operate in many aspects of DNA metabolism such as progression of the replication forks, recombination and repair has been recently suggested. In addition, sgs1 gene product in yeast, homologous to WS gene, has been shown to physically interact with topoisomerase types I and II. Earlier data from our laboratory suggested that WRN helicase might play a role in a G2 recombinational pathway of double strand breaks (DSBs) repair, co-operating with topoisomerase II. In this work, the effect of the topoisomerase I inhibitor camptothecin in WS cells has been investigated at the chromosomal level. The data from the present work suggest that the inhibition of topoisomerase I activity by camptothecin results in a higher induction of chromosomal damage in WS cell lines in the G2-phase and in the S-phase of the cell cycle compared to normal cells, perhaps associated with the defects in DNA replication synthesis.

Evidence that camptothecin-induced aberrations in the G(2) phase of cell cycle of Chinese hamster ovary (CHO) cell lines is associated with transcription

It is widely accepted that camptothecin (CPT) is an S-dependent genotoxin. In this study, we aimed to elucidate the 'puzzling' induction of chromosomal damage by CPT in the G(2) phase of CHO cells, where no DNA synthesis is expected, focusing the attention on the possible role of the ongoing RNA synthesis, supposed to cause the conversion of CPT-single stranded cleavage complexes spaced closely on opposite DNA strands into DNA double strand breaks (DSB's) by the action of traversing RNA polymerase.CHO AA8 and its parental mutant EM9 cell lines were pre-treated with alpha-amanitin, which prevents transcription to pre-m-RNA and challenged cells with CPT for the last hour in culture to evaluate whether G(2)-CPT-induced aberrations would have been reduced or abolished in the absence of RNA synthesis compared with G(2)-CPT treatment alone. The results obtained indicated a marked and significant reduction of aberration yields, to almost the control values (alpha-amanitin alone) when inhibition of RNA synthesis was substantial (3h total alpha-amanitin). Partial inhibition of RNA synthesis (2h total alpha-amanitin) slightly reduced the CPT-induced aberrations yield only at the high dose-level employed of CPT (20mM). This finding strongly supports the hypothesis that CPT-single stranded cleavages complexes spaced closely on opposite DNA strands are converted into DNA double strand breaks by the action of traversing RNA polymerase.

Catalytic inhibition of topoisomerase II in Werner's syndrome cell lines enhances chromosomal damage induced by X-rays in the G2 phase of the cell cycle

PURPOSE

To investigate whether catalytic topoisomerase II activity by ICRF187, a compound that interferes with the catalytic cycle of topoisomerase II without causing DNA damage, could result in a modulation of X-ray-induced chromosomal damage in Werner's syndrome (WS) cell lines.

MATERIALS AND METHODS

Two WS (KO375, DJG) and one normal lymphoblastoid cell line (SNW646) were exposed to X-rays, post-treated with ICRF187 and harvested after various recovery times. Cell progression to mitosis was monitored by 5-bromo-2'-deoxyuridine (BrdUrd) and fluorescent immmunodetection to analyse chromosomal damage in homogeneous treated cell populations in the G1, S or G2 phase of the cell cycle.

RESULTS

In WS cell lines, catalytic inhibition of topoisomerase II activity by ICRF187 resulted in potentiation of X-ray- induced chromosomal damage in the G2 phase of the cell cycle. This potentiation was not observed in the G1 or S phases of the cell cycle, neither in WS nor normal cells.

CONCLUSION

These results point out the possibility that Werner's syndrome protein (WRNp) might play a role in a G2 recombinational pathway of double-strand break repair, cooperating with topoisomerase II and thus contributing to maintain genomic integrity.

Werner's syndrome lymphoblastoid cells are hypersensitive to topoisomerase II inhibitors in the G2 phase of the cell cycle

Werner's syndrome (WS) is a rare autosomal recessive human disorder and the patients exhibit many symptoms of accelerated ageing in their early adulthood. The gene (WRN) responsible for WS has been biochemically characterised as a 3'-5' helicase and is homologous to a number of RecQ superfamily of helicases. The yeast SGS1 helicase is considered as a human WRN homologue and SGS1 physically interacts with topoisomerases II and III. In view of this, it has been hypothesised that the WRN gene may also interact with topoisomerases II and III. The purpose of this study is to determine whether the loss of function of WRN protein alters the sensitivity of WS cells to agents that block the action of topoisomerase II. This study deals with the comparison of the chromosomal damage induced by the two anti-topoisomerase II drugs, VP-16 and amsacrine, in both G1 and G2 phases of the cell cycle, in lymphoblastoid cells from WS patients and from a healthy donor. Our results show that the WS cell lines are hypersensitive to chromosome damage induced by VP-16 and amsacrine only in the G2 phase of the cell cycle. No difference either in the yield of the induced aberrations or SCEs was found after treatment of cells at G1 stage. These data might suggest that in WS cells, because of the mutation of the WRN protein, the inhibition of topoisomerase II activity results in a higher rate of misrepair, probably due to some compromised G2 phase processes involving the WRN protein.

Lack of effect of caffeine post-treatment on X-ray-induced chromosomal aberrations in Werner's syndrome lymphoblastoid cell lines: a preliminary report

PURPOSE

To investigate whether in Werner's syndrome cells the G2 phase of the cell cycle has some abnormal response to post-treatment with agents such as caffeine and hydroxyurea known to interfere with cellular response to DNA damage.

MATERIALS AND METHODS

Two Werner's syndrome lymphoblastoid cell lines (KO375 and DJG) and the normal cell line SNW646 were exposed to 50 cGy of X-rays or mitomycin-C and posttreated with caffeine or hydroxyurea in the G2 phase of the cell cycle.

RESULTS

Hydroxyurea post-treatment potentiated the X-ray-induced aberration levels both in the normal and Werner's syndrome (KO375 and DJG) cell lines; in contrast caffeine was only effective in the normal cell line. Similar results were observed when Werner's syndrome cells were treated in the G1 phase with the S-dependent agent mitomycin-C and post-treated with caffeine in G2, extending the observation that Werner's syndrome cells are unaffected by caffeine G2 post-treatment.

CONCLUSIONS

These results show a lack of caffeine effect in Werner's syndrome cells, suggesting an involvement of the Werner's syndrome protein in the signal transduction pathway by which caffeine could override the DNA damage induced G2 checkpoint.

Chromosome radiosensitivity in human G2 lymphocytes and cell-cycle progression

PURPOSE

To investigate the possibility that the differential G2-phase radiosensitivity of human peripheral blood lymphocytes, found in normal individuals using the 'G2-phase chromosome radiosensitivity assay', could be attributed to heterogeneity in cellular progression to mitosis rather than differences in radiosensitivity.

MATERIALS AND METHODS

Human peripheral blood lymphocytes, from four different donors, were exposed to 50 cGy X-rays and sampled at different times. The progression of cells into mitosis was monitored by 5-bromo 2'-deoxyuridine (BrdUrd) incorporation.

RESULTS

The heterogeneous G2-phase chromosome radiosensitivity among different donors was abolished when homogeneous G2-phase cell populations were scored; they contained similar frequencies of cells in early or late G2-phase.

CONCLUSIONS

The heterogeneous G2-phase chromosome radiosensitivity, usually found in different normal donors, is caused by the analysis of different cell populations rather than reflecting intrinsic differences in radiosensitivity.

Caffeine effect on the mitotic delay induced by G2 treatment with UVC or mitomycin C

It is well established that DNA lesions trigger cell cycle check-points causing a mitotic delay that is required for their repair before cells enter the mitotic phase. Caffeine, in some cases, can remove this delay and consequently potentiates the yield of induced chromosome aberrations. The objective of this study was to test the effect of a G2 treatment with S-dependent agents (UV light and mitomycin C) on the cell kinetics of a G2 cell population and evaluate whether post-treatments with caffeine could modulate removal of the expected cell cycle delay. Cell kinetics were monitored by analysing the mitotic index (MI) values in combination with the 5-bromo-2'-deoxyuridine (BrdUrd) labelling technique. Chinese hamster fibroblast cultures (AA8) were treated in G2 phase of the cell cycle with 8 and 15 J/m2 UV light or 0.1 and 0.6 microgram/ml mitomycin C for 1.5 h. Post-treatments with caffeine were performed at dose levels and recovery times where the mitotic indices were substantially reduced. The results obtained showed that both UV light and mitomycin C induced a G2 arrest, as indicated by MI values and the absence of BrdUrd-labelled metaphases. For UV light the G2 block was observed at lower and higher dose levels after 1.5 h, while for mitomycin C it was observed only at the higher dose level after 1 h. However, in both cases the block lasted approximately 1 h, after which, even though slowed down, the cell population entered mitosis, as indicated by increased MI values. This block was not removed by caffeine post-treatment. In contrast, caffeine G2 post-treatment was able to remove G2 arrest induced by G1-S treatments. Accordingly, our results suggest that both UV light- and mitomycin C-induced damage must be processed during S phase to allow caffeine to remove induced G2 blocks.