Mid-term outcomes and complications of total knee arthroplasty in haemophilic arthropathy: A review of consecutive 131 knees between 2006 and 2015 in a single institute.

INTRODUCTION: Although total knee arthroplasty (TKA) in haemophilic arthropathy can reduce severe joint pain and improve functional disability, it is technically demanding. AIM: To evaluate mid-term outcomes and complications of TKA in haemophilic arthropathy. METHODS: This study retrospectively reviewed 131 consecutive primary TKAs in a single institute. The mean age was 41.0 years old, and the mean follow-up period was 6.8 years. Clinical and radiographic results were evaluated. Complications were categorized according to the classification system of the Knee Society for TKA complications. RESULTS: The average Western Ontario and McMaster Universities Arthritis Index (WOMAC) score improved from 66.0 to 24.2. The average flexion contracture significantly decreased from 17.3° to 4.7°, but the average pre- and postoperative maximum flexion did not differ (80.9° vs 85.6°, respectively). The average mechanical axis was varus 5.2° preoperatively and valgus 0.3° postoperatively. The coronal positions of the femoral and tibial components and the sagittal positions of these components were within ±3° in 83.2%, 89.3%, 63.4% and 73.3% of cases, respectively. Complications occurred in 17 knees (13.0%): hemarthrosis (n = 7), medial collateral ligament injury (n = 1), stiffness (n = 2), deep periprosthetic joint infection (PJI) (n = 3) and periprosthetic fracture (n = 4). CONCLUSIONS: The mid-term results of TKA in haemophilic arthropathy were satisfactory in pain relief, improved function and decreased flexion contracture. Bleeding and PJI continue to be major concerns for TKA in haemophilic arthropathy, and risk of periprosthetic fracture must be taken into account for patient education and appropriate prevention.

High prevalence of betanodavirus barfin flounder nervous necrosis virus as well as red-spotted grouper nervous necrosis virus genotype in shellfish.

Using two serially executed PCRs, the discriminative multiplex two-step RT-PCR (DMT-2 RT-PCR) following the detection seminested two-step RT-PCR (DSN-2 RT-PCR), we found a high frequency presence of BFNNV genotype as well as RGNNV in various domestic and imported shellfish. This was definitely different from the previous reports of outbreaks and asymptomatic infection only by the RGNNV genotype in cultured finfish in Korea. Cultivation of NNV entrapped in shellfish was performed successfully by a blind passage. Thus, in an attempt to elucidate the epidemiology of betanodavirus, experiments conducted on 969 shellfish samples concluded that (i) distribution of NNV genotype, especially BFNNV, in shellfish is clearly different from that found in finfish of the world; (ii) unlike RGNNV, which showed a high rate in summer, BFNNV showed no seasonal variation and this result suggests BFNNVs in the marine environment remain fairly constant throughout the year; and (iii) the entrapped virus in shellfish was alive and culturable in vitro. These results are the first report of high level prevalence of in vitro culturable NNV in shellfish, for both BFNNV and RGNNV, which may present a potential risk in transmitting nodaviruses to host species in a marine environment.

A natural infection by the red sea bream iridovirus-type Megalocytivirus in the golden mandarin fish Siniperca scherzeri.

An outbreak of a Megalocytivirus infection was found in the golden mandarin fish Siniperca scherzeri during September and October 2016, in Korea. Phylogeny and genetic diversity based on the major capsid protein (MCP) and adenosine triphosphatase (ATPase) genes showed a new strain. Designated as GMIV, this strain derived from the golden mandarin fish was suggested to belong to the red sea bream iridovirus (RSIV)-subgroup I. Additionally, this train clustered with the ehime-1 strain from red sea bream Pagrus major in Japan and was distinguished from circulating isolates (RSIV-type subgroup II and turbot reddish body iridovirus [TRBIV] type) in Korea. The infection level, evaluated by qPCR, ranged from 8.18 × 102 to 7.95 × 106  copies/mg of tissue individually, suggesting that the infected fish were in the disease-transmitting stage. The diseased fish showed degenerative changes associated with cytomegaly in the spleen as general sign of Megalocytivirus infection. The results confirm that the RSIV-type Megalocytivirus might have crossed the environmental and species barriers to cause widespread infection in freshwater fish.

Robot-assisted total knee arthroplasty in haemophilic arthropathy.

INTRODUCTION: Execution of total knee arthroplasty (TKA) in end-stage haemophilic arthropathy is challenging because of soft tissue fibrosis, flexion contractures, poor quality of the bone, and the altered bony anatomy. Restoring the lower limb alignment and achieving range of motion (ROM) is difficult. Robots have been used in TKA to reduce the chances of malalignment and improve accuracy and precision. However, there has been no report in literature on use of robots for TKA in haemophilic arthropathy. The aim of this study was to evaluate whether robot-assisted TKA can be successfully carried out in haemophilic arthropathy and what precision could be obtained. METHODS: Thirty-two robot-assisted TKA were evaluated in 29 haemophilia patients. The mean follow up period was 5 years (range, 3-7 years). Hip-knee-ankle (HKA) axis, component angles, and radiographic loosening were evaluated. Clinically ROM, Knee Society scores (KSS) and SF-36 were assessed. RESULTS: The HKA axis was within a range of 0 ± 3° in 30 knees (93.8%). The alignment of the components also presented satisfying results. KSS were improved from 27.1 to 82.8 postoperatively (P < 0.001). The ROM was improved from 70.7 to 84.7 postoperatively (P = 0.006). Complications included early haematoma in three knees, heterotopic ossification in three knees, periprosthetic infection in two knees. CONCLUSIONS: Though robotic TKA gives excellent accuracy of lower limb and component alignment, expensive cost, additional preparation time, longer operation time with similar clinical results in haemophilic arthropathy should be concerned.

Identification of metabolites produced by Phanerochaete chrysosporium in the presence of amlodipine orotate using metabolomics.

Pharmaceuticals are very useful in treating human diseases but they are excreted to the environment sometimes in their original form or as byproducts of human metabolism. Pharmaceuticals and their metabolites have been proven by studies to be harmful to non-target ecological species and may be persistent in different water matrices. In this regard, there is an emergent need to eliminate these compounds to prevent their adverse effects on aquatic species. Biodegradation using white-rot fungi is a promising technology for the removal of recalcitrant compounds; however, products of fungal biodegradation can also be detrimental. In this novel study, we evaluated the ability of Phanerochaete chrysosporium to degrade amlodipine, an anti-hypertensive drug which was recently found in water systems. Analysis of amlodipine metabolites was done using quadrupole time-of-flight liquid chromatography mass spectrometry after the degradation set-up of 120 hours. Pharmaceutical degradation was seen using triple quadrupole liquid chromatography tandem mass spectrometry. Ninety-two significant metabolites (P-value ≤ 0.05) were significantly expressed after false discovery rate adjustment at a significance threshold of q = 0.05. Pyridine derivatives which were identified from samples became the basis of the proposed degradation pathway of amlodipine in this study.

Efficacy and safety using autotransfusion system with postoperative shed blood following total knee arthroplasty in haemophilia.

The purpose of this study was to evaluate the efficacy and safety of postoperative wound drain salvage and autotransfusion system in haemophilic patients undergoing elective total knee arthroplasty (TKA). No literature exists on reinfusing drained blood in patient with haemophilia undergoing TKA. Eighty-eight knees of 66 patients received cemented TKA due to end-stage haemophilic arthropathy (group I; with autotransfusion in 59 knees, group II; without autotransfusion in 29 knees). In group I, the postoperative shed blood was transfused within 6 h after surgery. The amount of blood drainage and reinfused blood, rate and amount of allogenic transfusion, postoperative change of haemoglobin level, prothrombin time (PT) and activated partial thromboplastin time were analysed. The mean postoperative blood drainage was 932 ± 479 mL in group I and 830 ± 492 mL in group II (P > 0.05). The mean volume of blood reinfused was 530 ± 265 mL in group I. Allogenic transfusion was needed in six knees (10.2%) of group I and eight knees (27.6%) of group II (P = 0.036). The mean volume of allogenic transfusion was 480 ± 49 mL in group I and 1041 ± 691 mL in group II (P > 0.05). Changes of all the laboratory results before and after TKA showed no statistically significant difference except PT was prolonged in group I (P = 0.008) at postoperative day 1. Moreover, there was no significant complication related to either reinfusion or allogenic transfusion in both groups. This study showed that reinfusion of drained blood is a simple, safe and efficacious method in patients with haemophilia undergoing TKA.

Phenotypic traits, virulence-associated gene profile and genetic relatedness of Edwardsiella tarda isolates from Japanese eel Anguilla japonica in Korea.

UNLABELLED: Edwardsiella tarda is the predominant bacterium in farm-cultured eel in Korea. Here, we evaluated the heterogeneity of 37 E. tarda isolates derived from Japanese eel with various origins (olive flounder, common carp and ornamental fish) between 2003 and 2010. Regardless of origins, the biochemical characteristics of E. tarda isolates were homogenous except hydrogen sulfide production, citrate utilization and mannitol fermentation. Based on the phylogenetic analysis of 16S rRNA, E. tarda isolates could be classified into two subgroups and displayed a close relation with Edwardsiella ictaluri and Edwardsiella hosinae lineages, suggesting that the subgroup I has been a predominant type in the Jeonnam and Jeonbuk provinces. I-CeuI-based pulsed-field gel electrophoresis (PFGE) typing showed that the isolates from Japanese eels belonged to 11 pulsotypes, indicating that the presence of highly genomic diversity. Additionally, two isolates, ET-060 and ET-191, showed a high frequency of virulence genes (100%) and caused 90% and 60% mortality in Japanese eel, respectively. This finding suggests a substantial congruence of virulence gene profiles and pathogenicity. Our results demonstrate that the intraspecific diversity within E. tarda strains from Japanese eel has been in prior existence. SIGNIFICANCE AND IMPACT OF THE STUDY: Based on the biochemical characteristics, the phylogenetic property of the 16S rRNA gene and PFGE types of Edwardsiella tarda, we could identify the intraspecific diversity of isolates from Japanese eel, Anguilla japonica in Korea. In addition, this study describes the strong congruence of virulence-related genes and pathogenicity, suggesting that the virulence profile may be useful tool for prediction of pathogenicity.

Treatment of distal femur fractures with locking plates: Comparison of periprosthetic fractures above total knee arthroplasty and non-periprosthetic fractures.

The purpose of the present study was to compare the results and plate fit of periprosthetic and non-periprosthetic distal femur fractures fixed with locking plates. Twenty-one periprosthetic fractures above a TKA and 27 non-periprosthetic fractures were retrospectively reviewed. The primary healing rate, bone union time, clinical and radiographic results, complications, and additional surgeries were compared between the two groups. The quality of the plate fit on the bone was also compared. There were no differences in the primary healing rate, bone union time, clinical and radiographic results between the two groups. The incidence of overall complication and additional surgeries did not differ (3/21 vs. 5/27, 1/21 vs. 4/27). Plate fit trouble was observed more frequently in periprosthetic fractures (10/21 vs. 1/27, p = 0.004). Fixation of distal femur fractures with locking plates provided satisfactory results with a low risk of complications and additional surgeries in both periprosthetic and non-periprosthetic fractures.

Computer-navigated total knee arthroplasty in haemophilic arthropathy.

Total knee arthroplasty (TKA) in end-stage haemophilic arthropathy is complex and challenging due to the altered bony anatomy, arthrofibrosis and muscle contractures. Computer navigation is especially advocated in patients with deformity or altered anatomy to improve alignment and to assist in ligament balancing. The objective of this study was to evaluate the results of computer-navigated TKA in haemophilic arthropathy. A consecutive series of computer-assisted TKA for the end-stage haemophilic arthropathy between February 2007 and December 2009 were evaluated. A total of 27 TKA were performed in 25 patients. Pre- and postoperative full-length weight-bearing radiographs were assessed for the axial limb alignment. The orientation of the components was measured on anteroposterior radiographs. Clinically, Knee Society score and Short Form-36 were evaluated. The mechanical axis of the leg was within a range of ±3° varus/valgus in 92% of the TKA. The coronal alignment of the femoral and tibial components was within a range of ±3 degrees in 96% of the knees. The clinical outcomes were significantly improved after the operation. There were no complications specific to the computer navigation. Computer-navigated TKA helps in restoring the mechanical axis and improves accuracy of orientation of the components in patients with end-stage haemophilic arthropathy. Potential benefits in long-term outcome require further investigation.

Environmental lung diseases: clinical and imaging findings.

Environmental lung diseases are caused by exposure to adverse environmental conditions, such as atmospheric pressure changes or the ingestion or inhalation of toxic agents. The development of environmental lung diseases depends on the intensity and duration of exposure, the physiological and biological susceptibility of the host, and the toxic effects of the adverse environmental conditions encountered. A combination of clinical features, related exposure history, imaging findings, and a review of previous reports that support an association between exposure and the disease process is required for diagnosis.

Comparison of chest digital tomosynthesis and chest radiography for detection of asbestos-related pleuropulmonary disease.

AIM: To compare chest digital tomosynthesis (DTS) with digital radiography for the detection of asbestos-related pleuropulmonary disease. MATERIALS AND METHODS: The institutional review board approved this study and all participants gave informed consent. Forty-five participants with a history of asbestos exposure were examined with DTS and radiography. Low-dose multidetector computed tomography (CT) in the prone position served as the reference. Two observers evaluated all images for the presence of pleural abnormalities and asbestosis. Interobserver agreement was analysed by using the k statistic. Diagnostic performance of the two imaging methods was compared using McNemar's test. RESULTS: Interobserver agreement regarding DTS findings was moderate to very good (k = 0.544-0.846) and superior to the radiographic findings (k = 0.236-1.000). Overall, the diagnostic accuracy of DTS for the lesion detection was significantly better than with radiography (all p < 0.05, except that for the comparison of diagnostic accuracy of DTS versus radiographic detection of left diaphragmatic plaques and asbestosis). DTS was more sensitive than radiography for the detection of asbestosis (82% versus 27%, p = 0.031). CONCLUSION: DTS is more accurate than radiography in the detection of pleural plaques and more sensitive than radiography in the detection of asbestosis. Interobserver agreements with respect to the DTS findings were superior to the radiographic findings.

Radioisotope synoviorthesis with Holmium-166-chitosan complex in haemophilic arthropathy.

Radiosynoviorthesis is a safe and easy method for synovectomy in haemophilic arthropathy. Various agents have been used in radiosynoviorthesis, especially newly developed agent Holmium-166-chitosan complex has good clinical outcome. This study analysed clinical results and radiologic evaluation of radioisotope synoviorthesis using Holmium-166-chitosan complex in haemophilic arthropathy. From March 2001 to December 2003, 58 radiosynoviorthesis were performed in 53 haemophiliacs. The average age at procedure was 13.8 years. The Arnold and Hilgartner stage of the patients was from I to IV. Holmium-166-chitosan complex was injected in 31 ankle joints, 19 elbow joints and 8 knee joints. Average follow-up was 33 months since primary procedure. The range of motion of each joint, frequency of intra-articular bleeding and factor dose used were analysed for clinical assessment. There was no significant improvement of range of motion in affected joints. After procedure, the average frequency of bleeding of the elbow joint has decreased from 3.76 to 0.47 times per month, the knee joint from 5.87 to 1.12 times per month, and the ankle joint from 3.62 to 0.73 times per month respectively (P < 0.05). After treatment, the average coagulation factor dose injected was significantly decreased to 779.3 units per month from 2814.8 units per month before treatment (P < 0.001). Radioisotope synoviorthesis with Holmium-166-chitosan complex in haemophilic arthropathy is a very safe and simple procedure with the expectation of a satisfactory outcome without serious complication. It has excellent bleeding control effect on target joint and the need for substitution of coagulation factor concentrate can be reduced.

The outcome of cementless total hip arthroplasty in haemophilic hip arthropathy.

Total hip arthroplasty (THA) in haemophilic arthropathy is reported to be less successful than in non-haemophilic indications. Although preliminary results are encouraging, the survival and functional outcome of cementless THA in haemophilia are not known. The aim of this study was to analyse mid-term results of cementless THA in haemophilia. Twenty-seven consecutive cementless THAs with 23 patients performed between June 1995 and June 2003 were reviewed. Mean age at time of operation was 36 years and mean follow-up period was 92 months (range, 60-156). Radiographic assessment was done for fixation of components, loosening, osteolysis, wear and bone responses around the implants. The factor requirements, amount of transfusion and complications associated with bleeding were studied. The mean preoperative Harris hip score changed from 57 to 95.9 at the latest follow-up. The survival at mean follow-up was 95.2%. One patient with osteolysis around acetabular cup was re-operated with bone-grafting and change of polyethylene liner. One loose cup was revised with a cemented cup. All other components were deemed stable at the latest follow-up. A standardized management protocol and dedicated team approach comprising of haematologist, physicians, physical therapist, nurses and coordinators is needed for excellent results. The present retrospective study shows that the functional results of cementless THA in haemophilia are satisfactory as it happens in osteoarthritic patients according to the current literature, mainly the younger. Thus, taking into account that the majority of haemophilia patients requiring a THA are relatively young, cementless THA is currently recommended.

Relationship between Within-Visit Blood Pressure Variability and Skeletal Muscle Mass.

Sarcopenia, defined as loss of skeletal muscle mass and function with age, is an important health issue in aging society. We tried to investigate the relationship between blood pressure variability and skeletal muscle mass in nation-wide large population cohort. This cross-sectional study was based on data acquired in the Korea National Health and Nutrition Examination Survey (KNHANES), conducted from 2009 to 2011 by the Korean Centers for Disease Control and Prevention. We included 14,481 participants (age ≥ 20 years, male 6,302) for the analysis who had both blood pressure and whole-body dual energy X-ray absorptiometry (DXA) scan data. As an intra-individual within-visit blood pressure variability index, we calculated standard deviation (SD), coefficient of variation (CV), and maximum minus minimum BP difference (MMD) of systolic and diastolic blood pressure, which was measured 3 times. Appendicular skeletal muscle mass (ASM) was the sum of lean masses of both arms and legs. We adjusted ASM by body mass index. Significant inverse relationship was observed between blood pressure variability index (SD, CV, and MMD) and adjusted ASM. Blood pressure variability index were significantly higher in the lowest ASM quintile group both in male and female participants (p<0.001). In multivariate analysis, blood pressure variability index were significantly associated with ASM, even after adjusting confounding factors (p<0.001). In conclusion, hemodynamic influence may play an important role in the development of sarcopenia.

Comparison of mode of failure between primary and revision total knee arthroplasties.

INTRODUCTION: Cognizance of common reasons for failure in primary and revision TKA, together with their time course, facilitates prevention. However, there have been few reports specifically comparing modes of failure for primary vs. revision TKA using a single prosthesis. The goal of the study was to compare the survival rates, modes of failure, and time periods associated with each mode of failure, of primary vs. revision TKA. HYPOTHESIS: The survival rates, modes of failure, time period for each mode of failure, and risk factors would differ between primary and revision TKA. MATERIAL AND METHODS: Data from a consecutive cohort comprising 1606 knees (1174 patients) of primary TKA patients, and 258 knees (224 patients) of revision TKA patients, in all of whom surgery involved a P.F.C® prosthesis (Depuy, Johnson & Johnson, Warsaw, IN), was retrospectively reviewed. The mean follow-up periods of primary and revision TKAs were 9.2 and 9.8 years, respectively. RESULTS: The average 10- and 15-year survival rates for primary TKA were 96.7% (CI 95%,±0.7%) and 85.4% (CI 95%,±2.0%), and for revision TKA 91.4% (CI 95%,±2.5%) and 80.5% (CI 95%,±4.5%). Common modes of failure included polyethylene wear, loosening, and infection. The most common mode of failure was polyethylene wear in primary TKA, and infection in revision TKA. The mean periods (i.e., latencies) of polyethylene wear and loosening did not differ between primary and revision TKAs, but the mean period of infection was significantly longer for revision TKA (1.2 vs. 4.8 years, P=0.003). DISCUSSION: Survival rates decreased with time, particularly more than 10 years post-surgery, for both primary and revision TKAs. Continuous efforts are required to prevent and detect the various modes of failure during long-term follow-up. Greater attention is necessary to detect late infection-induced failure following revision TKA. LEVEL OF EVIDENCE: Case-control study, Level III.

Low Hemoglobin A1c Increases the Risk of Disability in Community-dwelling Older Non-diabetics Adults.

OBJECTIVE: To describe the health characteristics of individuals with low HbA1c levels and evaluate the association between HbA1c level and disability or all-cause mortality in non-diabetic older adults. DESIGN: Prospective observational cohort study. SETTING: Seongnam, Gyeongi Province, Korea. PARTICIPANTS: Among the 1,000 community-dwelling Koreans ≥ 65 years of age who were followed for 5 years, 760 non-diabetic individuals were analyzed. MEASUREMENTS: Activities of Daily Living (ADL) and Instrumental ADL (IADL) were evaluated and mortality data were obtained from the National Statistics Office of Korea. RESULTS: The mean age was 76.3 (SD 9.0) years, and 319 subjects (42.0%) were male. Lower level of HbA1c was associated with less frequent hypertension and less frequent use of aspirin or statin, and lower values of body mass index, hematocrit, total iron-binding capacity, albumin, and cholesterol level. The participants were categorized into 3 groups according to their HbA1c (group I, < 5.5%; group II, 5.5~5.9%; and group III, 6.0 ~ 6.4%). Although, there was no significant difference in functional status according to baseline HbA1c level, disability was more frequently observed as the HbA1c level decrease (18.3% in group I, 12.5% in group II, and 5.3% in group III, p=0.029) at the 5-year follow-up evaluation. There were 172 deaths (22.6%) during the follow-up period. There was no significant difference in mortality among the groups, however, group I had a 2.071-fold higher risk for the incident disability or mortality over group III after adjusting age, gender, and possible confounder (95% CI: 1.040 ~ 4.124, p=0.038). CONCLUSIONS: Lower level of HbA1c was associated with an increased risk of disability in non-diabetic older adults.

Selective degradation of unfolded proteins by the self-compartmentalizing HtrA protease, a periplasmic heat shock protein in Escherichia coli.

HtrA, which has a high molecular mass of about 500 kDa, is a periplasmic heat shock protein whose proteolytic activity is essential for the survival of Escherichia coli at high temperatures. To determine the structural organization of HtrA, we have used electron microscopy and chemical cross-linking analysis. The averaged image of HtrA with end-on orientation revealed a six-membered, ring-shaped structure with a central cavity, and its side-on view showed a two-layered structure. Thus, HtrA behaves as a dodecamer consisting of two stacks of hexameric ring. HtrA can degrade thermally unfolded citrate synthase and malate dehydrogenase but cannot when in their native form. HtrA degraded partially unfolded casein more rapidly upon increasing the incubation temperature. However, it hydrolyzed oxidized insulin B-chain, which is fully unfolded, at nearly the same rate at all of the temperatures tested. HtrA also rapidly degraded reduced insulin B-chain generated by treatment of insulin with dithiothreitol but not A-chain or intact insulin. Moreover, HtrA degraded fully unfolded alpha-lactalbumin, of which all four disulfide bonds were reduced, but not the native alpha-lactalbumin and its unfolded intermediates containing two or three disulfide bonds. These results indicate that unfolding of the protein substrates, such as by exposure to high temperatures or reduction of disulfide bonds, is essential for their access into the inner chamber of the double ring-shaped HtrA, where cleavage of peptide bonds may occur. Thus, HtrA with a self-compartmentalizing structure may play an important role in elimination of unfolded proteins in the periplasm of Escherichia coli.

Heptameric ring structure of the heat-shock protein ClpB, a protein-activated ATPase in Escherichia coli.

The heat-shock protein ClpB is a protein-activated ATPase that is essential for survival of Escherichia coli at high temperatures. ClpB has also recently been suggested to function as a chaperone in reactivation of aggregated proteins. In addition, the clpB gene has been shown to contain two translational initiation sites and therefore encode two polypeptides of different size. To determine the structural organization of ClpB, the ClpB proteins were subjected to chemical cross-linking analysis and electron microscopy. The average images of the ClpB proteins with end-on orientation revealed a seven-membered, ring-shaped structure with a central cavity. Their side-on view showed a two-layered structure with an equal distribution of mass across the equatorial plane of the complex. Since the ClpB subunit has two large regions containing consensus sequences for nucleotide binding, each layer of the ClpB heptamer appears to represent the side projection of one of the major domains arranged on a ring. In the absence of salt and ATP, the ClpB proteins showed a high tendency to form a heptamer. However, they dissociated into various species of oligomers with smaller sizes, depending on salt concentration. Above 0.2 M NaCl, the ClpB proteins behaved most likely as a monomer in the absence of ATP, but assembled into a heptamer in its presence. Furthermore, mutations of the first ATP-binding site, but not the second site, prevented the ATP-dependent oligomerization of the ClpB proteins in the presence of 0.3 M NaCl. These results indicate that ClpB has a heptameric ring-shaped structure with a central cavity and this structural organization requires ATP binding to the first nucleotide-binding site localized to the N-terminal half of the ATPase.