Comparison between the LMA Classic™ and New I-gel™ Supraglottic Airway Device: A Manikin Study

Objective

It is nowadays well established that the laryngeal mask airway (LMA) is an alternative airway to endotracheal intubation for prehospital environment. However, problems have been reported and many other kinds of supraglottic airway devices (SGDs) were introduced. The I-gel™ is one of the latest SGD, and it has been designed for easy and fast insertion with non-inflatable cuff. We compared the efficacy between LMA Classic™ and I-gel™ by using both normal and difficult airway conditioned manikin.

Methods

One hundred and two non-experienced volunteers made out of students and nurses participated in the airway management educational program that was held in the emergency medical center of Gwangmyeong Sungae Hospital. After finishing the program, the participants were tested on their performance skills (insertion time) on using the two devices in both normal and difficult airway conditioned manikin. A structured questionnaire was used to measure the knowledge, attitude and preference about each device on a 5-point scale.

Results

In the LMA Classic™ and I-gel™ groups, it took 28.3±8.3 and 10.0±3.7 seconds with normal airway conditioned manikin (p<0.001), and 29.1±8.2 and 10.3±3.0 seconds elapsed with difficult airway conditioned manikin to achieve adequate airway management (p<0.001) in the corresponding order. The attitude and preference scale of the I-gel™ was higher than those of the LMA Classic™ (p<0.001).

Conclusions

The insertion time of the I-gel™ was shorter than that of the LMA Classic™ in both normal and difficult airway conditioned manikin, and I-gel™ had a higher positive response for attitude and preference.

Infectious complications following allogeneic stem cell transplantation: reduced-intensity vs. myeloablative conditioning regimens

BACKGROUND

In allogeneic stem cell transplantation (allo-SCT), reduced-intensity conditioning (RIC) is known for producing less regimen-related toxicity. However, whether or not RIC reduces the risk for infection and infection-related mortality (IRM) remains controversial.

METHODS

We retrospectively analyzed infectious episodes and IRMs after allo-SCTs by time period and by the intensity of the conditioning regimen (RIC [n = 81] vs. myeloablative conditioning, MAC [n = 150]).

RESULTS

The cumulative incidence of any kind of infection was lower in the RIC group through the entire period (72% vs. 87%; P = 0.007). The onset of infections was deferred in the RIC group as compared with the MAC group (P = 0.012). Bacteremia occurred less frequently in the RIC group through the entire period (5% vs. 14%; P = 0.044). However, the incidences of cytomegalovirus reactivation and disease, herpes zoster, virus-associated hemorrhagic cystitis, and invasive fungal infection were not different between the two groups. Furthermore, there was no difference in relapse-free survival and IRM between the two conditioning regimens.

CONCLUSION

Careful monitoring and appropriate preventive/therapeutic strategies for infectious complications, comparable to those for allo-SCT recipients with MAC, should also be applied to those with RIC, especially after engraftment.

PET/CT and MRI of intra-osseous haemangioma of the tibia

Intra-osseous haemangioma is a rare, benign neoplasm that usually involves the vertebrae and craniofacial bones. Furthermore, its occurrence in the long bones is extremely rare. We report the findings of fluorine-18-fludeoxyglucose ((18)F-FDG) positron emission tomography (PET)/CT and MRI in a patient with intra-osseous haemangioma in the proximal tibia, who was initially misdiagnosed as having a malignancy based on (18)F-FDG PET/CT. (18)F-FDG PET/CT showed a well-marginated osteolytic lesion with abnormal FDG uptake. The mass demonstrated low signal intensity on T(1) weighted MRI. On T(2) weighted images, the lesion appeared as a cluster of high signal intensity lobules and showed strong enhancement on contrast-enhanced T(1) weighted images. Surgical curettage was performed and histopathological examination of the excised tissue confirmed a cavernous haemangioma.

Kikuchi disease: differentiation from tuberculous lymphadenitis based on patterns of nodal necrosis on CT

BACKGROUND AND PURPOSE

KD, also known as histiocytic necrotizing lymphadenitis, is often mimicked by TL, especially when KD is accompanied by gross necrosis on CT. We analyzed the nodal necrosis patterns on CT in patients with KD and TL to identify the predictive features that differentiate these 2 entities.

MATERIALS AND METHODS

We included 24 patients with KD (14 females, 10 males; mean age, 25.1 years) and 45 with TL (36 women, 9 men; mean age, 39.9 years) having nodal necrosis on CT. The extent, number, location, and margins of nodal necrosis; the presence of perinodal infiltration; and nodal calcification were analyzed. Two attenuation indices for nodal necrosis were derived: CTN and CTN/M. The CT features of the 2 diseases were compared, and multivariate logistic regression analysis was performed to identify predictive features that would aid in differentiating KD from TL.

RESULTS

Mild or moderate extent of nodal necrosis (P = .000), multiple necrotic foci (P = .002), indistinct margins of necrotic foci (P = .000), CTN of >44.5 (P = .000), CTN/M of >0.7 (P = .000), and absence of nodal calcification (P = .012) were associated with KD. Multivariate logistic regression analysis revealed that indistinct margins of necrotic foci were independent predictors, with 80% accuracy.

CONCLUSIONS

The presence of indistinct margins of necrotic foci was an independent predictor in differentiating KD from TL with high diagnostic accuracy.

Early-onset Charcot-Marie-Tooth patients with mitofusin 2 mutations and brain involvement

Mutations of the mitofusin 2 (MFN2) gene have been reported to be the most common cause of the axonal form of Charcot-Marie-Tooth disease (CMT). A prospective brain MRI study was performed on 18 early-onset CMT patients with MFN2 mutations, and a high frequency (39%) of brain abnormalities was found. Early-onset patients showed multiple scattered or confluent brain lesions that involved gray matter as well as white matter. Patterns of brain involvement in early-onset patients differed from those of late-onset patients and other hereditary peripheral neuropathies. In addition, one CMT patient demonstrated a brain lesion before the development of peripheral neuropathy.

A computerized tomography scan method for calculating the hernia sac and abdominal cavity volume in complex large incisional hernia with loss of domain

Preoperative progressive pneumoperitoneum (PPP) is a safe and effective procedure in the treatment of large incisional hernia (size > 10 cm in width or length) with loss of domain (LIHLD). There is no consensus in the literature on the amount of gas that must be insufflated in a PPP program or even how long it should be maintained. We describe a technique for calculating the hernia sac volume (HSV) and abdominal cavity volume (ACV) based on abdominal computerized tomography (ACT) scanning that eliminates the need for subjective criteria for inclusion in a PPP program and shows the amount of gas that must be insufflated into the abdominal cavity in the PPP program. Our technique is indicated for all patients with large or recurrent incisional hernias evaluated by a senior surgeon with suspected LIHLD. We reviewed our experience from 2001 to 2008 of 23 consecutive hernia surgical procedures of LIHLD undergoing preoperative evaluation with CT scanning and PPP. An ACT was required in all patients with suspected LIHLD in order to determine HSV and ACV. The PPP was performed only if the volume ratio HSV/ACV (VR = HSV/ACV) was >or=25% (VR >or= 25%). We have performed this procedure on 23 patients, with a mean age of 55.6 years (range 31-83). There were 16 women and 7 men with an average age of 55.6 years (range 31-83), and a mean BMI of 38.5 kg/m(2) (range 23-55.2). Almost all patients (21 of 23 patients-91.30%) were overweight; 43.5% (10 patients) were severely obese (obese class III). The mean calculated volumes for ACV and HSV were 9,410 ml (range 6,060-19,230 ml) and 4,500 ml (range 1,850-6,600 ml), respectively. The PPP is performed by permanent catheter placed in a minor surgical procedure. The total amount of CO(2) insufflated ranged from 2,000 to 7,000 ml (mean 4,000 ml). Patients required a mean of 10 PPP sessions (range 4-18) to achieve the desired volume of gas (that is the same volume that was calculated for the hernia sac). Since PPP sessions were performed once a day, 4-18 days were needed for preoperative preparation with PPP. The mean VR was 36% (ranged from 26 to 73%). We conclude that ACT provides objective data for volume calculation of both hernia sac and abdominal cavity and also for estimation of the volume of gas that should be insufflated into the abdominal cavity in PPP.

Decrease of D2 receptor binding but increase in D2-stimulated G-protein activation, dopamine transporter binding and behavioural sensitization in brains of mice treated with a chronic escalating dose 'binge' cocaine administration paradigm

Understanding the neurobiology of the transition from initial drug use to excessive drug use has been a challenge in drug addiction. We examined the effect of chronic 'binge' escalating dose cocaine administration, which mimics human compulsive drug use, on behavioural responses and the dopaminergic system of mice and compared it with a chronic steady dose (3 x 15 mg/kg/day) 'binge' cocaine administration paradigm. Male C57BL/6J mice were injected with saline or cocaine in an escalating dose paradigm for 14 days. Locomotor and stereotypy activity were measured and quantitative autoradiographic mapping of D(1) and D(2) receptors, dopamine transporters and D(2)-stimulated [(35)S]GTPgammaS binding was performed in the brains of mice treated with this escalating and steady dose paradigm. An initial sensitization to the locomotor effects of cocaine followed by a dose-dependent increase in the duration of the locomotor effect of cocaine was observed in the escalating but not the steady dose paradigm. Sensitization to the stereotypy effect of cocaine and an increase in cocaine-induced stereotypy score was observed from 3 x 20 to 3 x 25 mg/kg/day cocaine. There was a significant decrease in D(2) receptor density, but an increase in D(2)-stimulated G-protein activity and dopamine transporter density in the striatum of cocaine-treated mice, which was not observed in our steady dose paradigm. Our results document that chronic 'binge' escalating dose cocaine treatment triggers profound behavioural and neurochemical changes in the dopaminergic system, which might underlie the transition from drug use to compulsive drug use associated with addiction, which is a process of escalation.

Different clinical and magnetic resonance imaging features between Charcot-Marie-Tooth disease type 1A and 2A

Charcot-Marie-Tooth disease type 1A (CMT1A) is the more frequent cause of demyelinating CMT, and CMT2A is the most common cause of axonal CMT. We conducted a magnetic resonance imaging (MRI) study on 39 CMT1A and 21 CMT2A patients to compare their neuroimaging patterns and correlate with clinical features. CMT1A patients showed selective fatty infiltration with a preference for anterior and lateral compartment muscles, whereas CMT2A patients showed a preference for superficial posterior compartment muscles. Early-onset CMT2A patients showed more severe leg fatty atrophy than late-onset CMT2A patients. In late-onset CMT2A, soleus muscle was the earliest, and most severely affected than the other leg muscles. Selective involvement of intrinsic foot muscles is a characteristic pattern of minimal CMT1A and CMT2A. Our MRI study demonstrates different patterns of fatty infiltration involving superficial posterior compartment muscles in CMT2A (partial T-type), and peroneal nerve innervated muscles in CMT1A (P-type).

The relationship of the medially-offset stem of the tibial component to the medial tibial cortex in total knee replacements in Korean patients

We examined the placement of the stem in relation to the medial tibial cortex when using total knee replacements (TKRs) with medially-offset tibial stems in Korean patients. Measurements were performed on the pre- and post-operative radiographs of 246 osteoarthritic knees replaced between January 2005 and May 2006 using the Genesis II or E-motion TKR with a medially-offset stem. Pre-operatively, we measured the distance between the mechanical axis and that of the tibial shaft and post-operatively, that between the midline of the tibial stem and the axis of the shaft. Knees were identified in which there was radiological contact between the tip of the stem and the medial tibial cortex. The mechanical axis was located medial to the axis of the shaft in 203 knees (82.5%). Post-operatively, the midline of the tibial stem was located medial to the tibial shaft axis in 196 knees (79.7%). In 16 knees (6.5%) there was radiological contact between the tibial stem or cement mantle and the medial tibial cortex. Our study has shown that the medially-offset stem in the tibial component may not be a good option for knees undergoing replacement for advanced osteoarthritis in some Korean patients.

The determination of sensation-dependent bladder emptying time in patients with complete spinal cord injury above T11

STUDY DESIGN

Retrospective investigation using urodynamic studies and medical records.

OBJECTIVE

To evaluate the safety of sensation-dependent bladder emptying in complete spinal cord injury (SCI) patients, based on the preservation of the desire to void.

SETTING

Spinal Cord Injury Unit, Yonsei Rehabilitation Hospital, Seoul, Korea.

METHODS

This study was performed retrospectively on 79 complete SCI patients with lesions above T11, who had preserved the desire to void during conventional urodynamic studies. Patients were classified according to detrusor compliance and maximal bladder capacity. The clinical and urodynamic characteristics of each group were analyzed.

RESULTS

Forty-five (57.0%) patients were classified as group A and 34 (43.0%) patients were classified as group B. There were no significant differences in clinical features, such as voiding methods and the presence of autonomic dysreflexia between the two groups. Compared with group B, there were significantly more areflexic neurogenic bladder cases in group A (P<0.05). There were significantly higher maximal detrusor pressures in group B (P<0.05). There were significantly more cases with the preservation of the strong desire to void in group B (P<0.05).

CONCLUSION

Not all patients with discomplete SCIs accepted the use of sensation-dependent bladder emptying. The safe use of sensation-dependent bladder emptying will be determined based on the results of urodynamic studies.

Preprodynorphin mediates locomotion and D2 dopamine and mu-opioid receptor changes induced by chronic 'binge' cocaine administration

Evidence suggests that the kappa-opioid receptor (KOP-r) system plays an important role in cocaine addiction. Indeed, cocaine induces endogenous KOP activity, which is a mechanism that opposes alterations in behaviour and brain function resulting from repeated cocaine use. In this study, we have examined the influence of deletion of preprodynorphin (ppDYN) on cocaine-induced behavioural effects and on hypothalamic-pituitary-adrenal axis activity. Furthermore, we have measured mu-opioid receptor (MOP-r) agonist-stimulated [(35)S]GTPgammaS, dopamine D(1), D(2) receptor and dopamine transporter (DAT) binding. Male wild-type (WT) and ppDYN knockout (KO) mice were injected with saline or cocaine (45 mg/kg/day) in a 'binge' administration paradigm for 14 days. Chronic cocaine produced an enhancement of locomotor sensitisation in KO. No genotype effect was found on stereotypy behaviour. Cocaine-enhanced MOP-r activation in WT but not in KO. There was an overall decrease in D(2) receptor binding in cocaine-treated KO but not in WT mice. No changes were observed in D(1) and DAT binding. Cocaine increased plasma corticosterone levels in WT but not in KO. The data confirms that the endogenous KOP system inhibits dopamine neurotransmission and that ppDYN may mediate the enhancement of MOP-r activity and the activation of the hypothalamic-pituitary-adrenal axis after chronic cocaine treatment.

Inhibitory effects of berberine against morphine-induced locomotor sensitization and analgesic tolerance in mice

We previously reported that a methanolic extract of Coptis japonica, which is a well-known traditional oriental medicine, inhibits morphine-induced conditioned place preference (CPP) in mice. Berberine is a major component of Coptis japonica extract, and it has been established that the adverse effects of morphine on the brain involve dopamine (DA) receptors. However, to our knowledge, no study has investigated the inhibitory effects of berberine on morphine-induced locomotor sensitization and analgesic tolerance in mice. Here, we investigated the effects of berberine on morphine-induced locomotor sensitization and on the development of analgesic tolerance. Furthermore, we examined the effects of berberine treatment on N-methyl-D-aspartate (NMDA) receptor channel activity expressed in Xenopus laevis oocytes. Berberine was found to completely block both morphine-induced locomotor sensitization and analgesic tolerance, and reduce D(1) and NMDA receptor bindings in the cortex. Moreover, berberine markedly inhibited NMDA current in Xenopus laevis oocytes expressing NMDA receptor subunits. Our results suggest that the inhibitory effects of berberine on morphine-induced locomotor sensitization and analgesic tolerance are closely related to the modulation of D1 and NMDA receptors, and that berberine should be viewed as a potential novel means of attenuating morphine-induced sensitization and analgesic tolerance.

Long-term outcome of per anum intersphincteric rectal dissection with direct coloanal anastomosis for lower rectal cancer

OBJECTIVE

The authors have performed per anum intersphincteric rectal dissection. With direct coloanal anastomosis for cases of lower rectal cancer in which the distal surgical margin is difficult to secure by the double stapling technique. The aim of this study was to evaluate the long-term outcome and to clarify the surgical indications for this operation.

PATIENTS AND METHODS

Between 1993 and 2002, 31 patients underwent per anum intersphincteric rectal dissection with direct coloanal anastomosis. Of these, two patients (one stage 0 and one stage IV) were excluded from the analysis of oncological outcome. The remaining 29 patients formed the basis of this study. The median follow-up was 57 months (range 6-106 months).

RESULTS

Local recurrence and distant metastasis developed in 9 and 3 patients, respectively. Local recurrence rate for pT1 was significantly lower than that for pT2/T3 disease. The local recurrence rate cases with tumours less than 3 cm was significantly lower than that for tumours sized 3 cm or more. The distant metastasis rate for cases with lymph node metastasis was significantly higher than that for cases without lymph node metastasis. There was an association between distant metastasis and TNM or pT stage. The overall survival rates for stage I, II and III were 85%, 80% and 89%, respectively. No significant difference was seen in total Cleveland Clinic incontinence score between per anum intersphincteric rectal dissection with direct coloanal anastomosis and the double stapling technique.

CONCLUSION

The surgical indications of this operation should be limited to patients with T1 rectal cancer or tumours less than 3 cm.

Infectious complications and outcomes after allogeneic hematopoietic stem cell transplantation in Korea

We reviewed 242 allogeneic hematopoietic stem cell transplantation (HSCT) recipients retrospectively over a 2-year period (January 1998-December 1999) in order to analyze the characteristics and assess the outcomes of infectious complications in patients after HSCT in Korea. Bacteria were the major pathogens before engraftment, and viral and fungal infections predominated during the post-engraftment period. Varicella zoster virus was the most common viral pathogen after engraftment. Cytomegalovirus disease occurred mainly in the late-recovery phase. The frequency of mold infection was higher than that of yeast. There was a relatively high incidence of tuberculosis (3.0%) and Pneumocystis carinii pneumonia (6.5%). One case of death by measles confirmed by autopsy was also noted. Overall, cumulative mortality was 43% (104/242), and 59.6% of these deaths (62/104) were infection-related. Allogeneic HSCT recipients from unrelated donors were prone to infectious complication and higher mortality than those from matched sibling (17/39 (43.6%) vs 45/203 (22.2%), respectively; P<0.01; odd ratio 2.5; 95% confidence interval 1.2-5.1). As infection was the main post-HSCT complication in our data, more attention should be given to the management of infections in HSCT recipients.

Interaction of separated ferromagnetic domains in a hole-doped manganite achieved by a magnetic field

We report the change in the magnetic microstructure with the application of a magnetic field to a hole-doped manganite La0.81Sr0.19MnO3 in the mixed-phase state, in which ferromagnetic and paramagnetic phases coexist. In situ observations by electron holography have revealed that the applied magnetic field generates a "channel" of the magnetic flux in the paramagnetic phase region, thereby connecting the separated ferromagnetic domains. The magnetic flux density of this channel is estimated at 0.33 T, which is comparable with that of the ferromagnetic domains. The connection of the separated ferromagnetic domains appears to promote the conduction in the mixed-phase state as predicted for many manganites exhibiting the magnetoresistance effect.

Nanocomposite magneto-rheological fluids with uniformly dispersed Fe nanoparticles

A systematic study of the magnetic and rheological properties of magneto-rheological (MR) fluids containing micron-size and nano-size iron particles is presented. The MR fluids were prepared with hydraulic oil as the carrier liquid and lecithin as an effective surfactant medium that promotes uniform particle dispersion. Magnetic measurements on micron-, hybrid-(nano + micron), and nano-MR fluids clearly indicate that the partial replacement of the micro-size particles by nanoparticles results in a better suspension and robust chain formation under applied external magnetic fields. For nano-MR fluids, the measured yield stress was found to be lower than micron-MR fluids. However, better flow properties and sharper magnetic switching make nanoparticle-based MR fluids appealing for microfluidics device applications where higher yield stress is not required.

Computed tomographic findings of the fractured mandibular condyle after open reduction

The purpose of this study was to evaluate the long-term radiological results obtained with open reduction and fixation of unilateral mandibular condyle fractures in 10 patients. CT images taken at the end of the follow-up period (average of 22 months, range 7 to 33 months), were traced and digitized, and the position and morphology of the fractured condylar process was statistically compared with those of the contralateral non-fractured condylar process in the coronal, transverse and sagittal planes. Little difference was observed in the position or morphology of the condylar process in the operated and non-fractured joints. This study shows that it is possible to anatomically reduce fractured condyles, and thereby to avoid postoperative disadvantageous joint changes.

Magnetization distribution in the mixed-phase state of hole-doped manganites

The effect of 'colossal magnetoresistance' (CMR) in hole-doped manganites--an abnormal decrease of resistivity when a magnetic field is applied--has attracted significant interest from researchers in the past decade. But the underlying mechanism for the CMR phenomenon is not yet fully understood. It has become clear that a phase-separated state, where magnetic and non-magnetic phases coexist, is important, but the detailed magnetic microstructure of this mixed-phase state is so far unclear. Here we use electron microscopy to study the magnetic microstructure and development of ferromagnetic domains in the mixed-phase state of La(1-x)Sr(x)MnO3 (x = 0.54, 0.56). Our measurements show that, in the absence of a magnetic field, the magnetic flux is closed within ferromagnetic regions, indicating a negligible magnetic interaction between separated ferromagnetic domains. However, we also find that the domains start to combine with only very small changes in temperature. We propose that the delicate nature of the magnetic microstructure in the mixed-phase state of hole-doped manganites is responsible for the CMR effect, in which significant conduction paths form between the ferromagnetic domains upon application of a magnetic field.

Experimental salivary pellicles formed on the surface of self-curing resin

The aim of this study was to identify the salivary components present in the pellicles formed on self-curing resin and to investigate the qualitative variations in adsorbed salivary pellicle compositions according to different exposure time to saliva. Experimental pellicles were formed by the incubation of polymerized resin particles with fresh human parotid or submandibular-sublingual saliva for either 20 min or 2 h. Pellicles were extracted using formic acid and lyophilized, they were then subjected to sodium dodecyl sulphate-polyacrylamide gel electrophoresis and immunoblotting to identify the adsorbed salivary components. The amino acid profiles of the 2 h-pellicles were analysed and compared with those of fresh glandular salivas. There was a difference in the 2 h-pellicle components on the self-curing resin compared with those of other dental materials as well as tooth enamel. The amino acid profiles of the 2 h-pellicles were also different from those of fresh glandular salivas. In the case of submandibular-sublingual saliva, the components of the 2 h-pellicle showed a different pattern compared with those of the 20 min-pellicle. However, there was no significant difference between the components of the 2 h- and 20 min-pellicles in the case of parotid saliva. A distinct difference was found in the surface binding affinities of immunoglobulin (IgA) from different glandular salivas. The findings of this study provide information concerning the initial bacterial adhesion on the surfaces of self-curing resin.

Aortobronchial fistula presenting as recurrent hemoptysis and successfully treated with an endovascular stent graft

Aortobronchial fistula (ABF) (aortopulmonary fistula) may cause a massive fatal hemoptysis. We have recently seen a patient with ABF presenting with recurrent, massive hemoptysis. She was successfully treated with an endovascular stent graft. The endovascular stent graft may provide an alternative treatment of in patients considered to be poor surgical candidates.

Determination of the native form of FadD, the Escherichia coli fatty acyl-CoA synthetase, and characterization of limited proteolysis by outer membrane protease OmpT

Several studies have described FadD, the Escherichia coli fatty acyl-CoA synthetase [also known as fatty acid:CoA ligase (AMP-forming); EC 6.2.1.3], as a 42-50 kDa enzyme. Based on sequencing and expression data from the fadD gene, other reports have suggested that FadD is a 62 kDa protein and represents the sole fatty acyl-CoA synthetase in E. coli. We report that the 62 kDa FadD enzyme is a substrate for the outer membrane protease OmpT in vitro, producing a 43 kDa C-terminal fragment and a 19 kDa N-terminal fragment. Immunoblotting with a FadD antibody revealed that only the 62 kDa form of the enzyme is present in vivo, but we utilized the proteolytic sensitivity of FadD to investigate its structure. Photoaffinity labelling experiments revealed that both intact FadD and the 43 kDa fragment bound a long-chain fatty acid. Intact and cleaved FadD were also purified to determine the effect of cleavage on function. When using oleate as a substrate, cleaved FadD displayed 2-fold higher K(m) and V(max) values compared with intact FadD, but the catalytic efficiencies (k(cat)/K(m)) of the two forms were similar. This indicated that cleavage did not adversely affect enzyme activity. Proteolysis of FadD by OmpT was altered by the presence of oleate or ATP, both of which are ligands for the fatty acyl-CoA synthetase. This suggested that FadD undergoes ligand-induced conformational changes and implies that the region surrounding the cleavage site is mobile, a common characteristic of linker domains.