Search

Results of previous immunological studies suggested that Borrelia burgdorferi regulates synthesis of the IpLA7 lipoprotein during mammalian infection. Through combined use of quantitative reverse transcription PCR, immunofluorescence analyses, ELISA and immunoblotting, it is now demonstrated that IpLA7 is actually expressed throughout mammalian infection, as well as during transmission both from feeding ticks to naive mice and from infected mice to naive, feeding ticks. However, proportions of IpLA7-expressing B. burgdorferi within tick midguts declined significantly with time following completion of blood feeding. Cultured bacteria differentially expressed IpLA7 in response to changes in temperature, pH and concentration of 4,5-dihydroxy-2,3-pentanedione, the precursor of autoinducer 2, indicative of mechanisms governing IpLA7 expression. Previous studies also reported mixed results as to the cellular localization of IpLAT. It is now demonstrated that IpLA7 localizes primarily to the borrelial inner membrane and is not surface-exposed, consistent with the ability of these bacteria to produce IpLA7 throughout mammalian infection despite being the target of a robust immune response. DOI 10.1099/mic.02006/003350-0

Surgeons may use laboratory tests, including erythrocyte sedimentation rate, C-reactive protein (CRP), and white blood cell count, as well as joint aspirations to diagnose prosthetic joint infections. There is a paucity of literature correlating preoperative inflammatory markers with risk of infection in the setting of salvage total hip arthroplasty (THA). This retrospective case analysis included patients who underwent a THA salvage procedure a minimum of 3 months after a failed fixation of a proximal femur or acetabulum, with a goal of assessing the utility of inflammatory markers as a screening tool in preoperative evaluation of salvage THA. Eighty-five patients met inclusion criteria. Thirteen patients were diagnosed with an infection preoperatively or intraoperatively during salvage THA. An elevated preoperative CRP level was a significant marker for infection. A CRP of 7.1 produced 80% sensitivity, 88% specificity, and a receiver operating characteristic curve of 0.840. There was a high rate of perioperative complications (17.6%) in salvage THA regardless of the presence of infection. In conclusion, CRP levels are useful in the preoperative evaluation for periprosthetic joint infection before salvage THA. [ABSTRACT FROM AUTHOR]

Predicting tissue outcome early after stroke is an important goal. MRI >3 h accurately predicts infarction but is insensitive to selective neuronal loss (SNL). Previous studies suggest that chronic-stage 11 C-flumazenil PET (FMZ-PET) is a validated marker of SNL in rats, while early-stage FMZ-PET may predict infarction. Whether early FMZ-PET also predicts SNL is unknown. Following 45-min distal MCA occlusion, adult rats underwent FMZ-PET at 1 h and 48 h post-reperfusion to map distribution volume (VT), which reflects GABA-A receptor binding. NeuN immunohistochemistry was performed at Day 14. In each rat, VT and %NeuN loss were determined in 44 ROIs spanning the hemisphere. NeuN revealed isolated SNL and cortical infarction in five and one rats, respectively. In the SNL subgroup, VT-1 h was mildly reduced and only weakly predicted SNL, while VT-48 h was significantly increased and predicted SNL both individually (p < 0.01, Kendall) and across the group (p < 0.001), i.e. the higher the VT, the stronger the SNL. Similar correlations were found in the rat with infarction. Our findings suggest GABA-A receptors are still present on injured neurons at the 48 h timepoint, and the increased 48 h VT observed here is consistent with earlier rat studies showing early GABA-A receptor upregulation. That FMZ binding at 48 h was predictive of SNL may have clinical implications. [ABSTRACT FROM AUTHOR]

In acute stroke, the target of therapy is the severely hypoxic but salvageable tissue. Previous human studies using 18F-fluoromisonidazole and positron emission tomography (18F-FMISO PET) have shown high tracer retention indicative of tissue hypoxia, which had normalized at repeat scan >48 h later. In the only validation study of 18F-FMISO, using ex vivo autoradiography in thread middle cerebral artery occluded (MCAo) rats, there was unexpected high uptake as late as 22 h after reperfusion, raising questions about the use of 18F-FMISO as a hypoxia tracer. Here we report a pilot study of 18F-FMISO PET in experimental stroke. Spontaneous hypertensive rats were subjected to distal clip MCAo. Three-hour dynamic PET was performed in 7 rats: 3 normals, 1 with permanent MCAo (two sessions: 30 mins and 48 h after clip), and 3 with temporary MCAo (45 mins, n=1; 120 mins, n=2; scanning started 30 mins after clip removal). Experiments were terminated by perfusion–fixation for standard histopathology. Late tracer retention was assessed by both compartmental modelling and simple side-to-side ratios. In the initial PET session of the permanent MCAo rat, striking trapping of 18F-FMISO was observed in the affected cortex, which had normalized 48 h later; histopathology revealed pannecrosis. In contrast, there was no demonstrable tracer retention in either temporary MCAo models, and histopathology showed ischemic changes only. These results document elevated 18F-FMISO uptake in the stroke area only in the early phase of MCAo, but not after early reperfusion nor when tissue necrosis has developed. These findings strongly support the validity of 18F-FMISO as a marker of viable hypoxic tissue/penumbra after stroke.Journal of Cerebral Blood Flow & Metabolism (2007) 27, 679–689. doi:10.1038/sj.jcbfm.9600405; published online 11 October 2006 [ABSTRACT FROM AUTHOR]

Intraarticular radial head (IARH) fractures are uncommon pediatric injuries with unpredictable yet poor outcomes. The aim of this study was to evaluate clinical outcomes of IARH fractures in pediatric and adolescent patients, by testing our hypothesis that surgically managed fractures would have less risk for an unplanned second surgery and better elbow range of motion at the final follow-up. A retrospective review of 53 IARH fractures was performed. Demographic and clinical data were recorded. Concomitant and associated injuries were documented. Initial management and any attempted reduction in the emergency room were documented. The primary outcome was the need for an unplanned second procedure. Motion at final follow-up, presence of pain and need for physical therapy were reviewed. Radiographs were carefully reviewed and analyzed for physeal status, displacement, angulation and percent of radial head involved. We rejected our hypothesis, however, because it was displaced fractures that tended to require an unplanned change in treatment at a higher rate than nondisplaced fractures, regardless of index management with or without surgery. Fracture displacement on the lateral radiograph was a significant risk factor compared to the anterior-posterior images, and younger patients, particularly those with open physis, were at higher risk of an unplanned second procedure. Moreover, 80% of displaced fractures had asymmetric elbow motion after healing was achieved. It is important to counsel patients and families regarding the potential for suboptimal outcomes and elbow stiffness regardless of treatment choice, in the setting of an initially displaced IARH fracture. Level of evidence: Level III., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

We aimed to assess the risk of conversion to surgical intervention in children initially managed with casting for an isolated scaphoid fracture with a secondary aim of assessing the incidence and management of occult scaphoid fractures without signs of fracture on initial radiographs. A retrospective review was performed. Our primary outcome was conversion to surgery. Subsequent evidence of fracture in those with only initial snuffbox tenderness was recorded for the secondary aim. Three hundred and eighty-four wrists with radiographic evidence of a scaphoid fracture were included. Twenty-one scaphoid fractures failed conservative treatment. Subjects that failed cast treatment were older than those that did not (15.9 years vs. 14.0 years; P < 0.001). Subjects with a delay in treatment of at least 6 weeks from injury were 8× more likely to require surgery than those with prompt treatment ( P < 0.001). Surgical conversion varied based on fracture location: distal pole 0.7%, waist 7.4%, and proximal pole 23.5% of the time ( P < 0.001). A total of 14% of wrists managed in a cast without radiographic evidence of fracture at presentation subsequently demonstrated a fracture on follow-up films. The primary predictor of failed conservative treatment is a delay in presentation. We found that the sequelae of delay in presentation or diagnosis of a scaphoid fracture increased the likelihood of requiring surgery. Therefore, clinical suspicion should dictate early management and these factors should play a role in determining when to initiate casting in the setting of pediatric scaphoid fractures. Level of evidence: III., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

The ideal technique to measure medial epicondyle humerus fracture displacement minimizes radiation exposure while maximizing measurement accuracy and reliability. This study compares the radiation exposure and accuracy of displacement measurements of the four-view X-ray examination (XR), computed tomography (CT) and in-clinic cone-beam CT (CBCT). A cadaveric humerus underwent medial epicondyle osteotomy. The fragment was fixed to the humerus at clinically relevant displacements (6 to 18 mm). Dosimeters were placed around the distal humerus and simulating thyroid location. XR, CT and CBCT were performed at each displacement. Four pediatric orthopedists measured the maximum linear displacement on each XR and 3D reconstruction of the CT and CBCT images. Focal (elbow location) and thyroid radiation exposure was compared between modalities. Intra- and interclass correlation coefficients (ICC) for displacement measurements were determined. Mean focal radiation exposures for XR, CT and CBCT were 0.008, 2.061 and 0.478 rad, respectively (P = 0.001). Exposures 10 inches from the elbow for XR, CT and CBCT were 0.001, 0.066 and 0.010 rad, respectively (P = 0.006). At 12 inches, there was no significant difference in exposure between XR and CBCT ( P  = 0.114). Intra- and interobserver reliabilities were excellent for all measures, except lateral x-ray. CBCT and CT had significantly less deviation from the actual displacement compared to XR ( P  < 0.05). In-office CBCT of the elbow exposes patients to significantly less radiation than conventional CT. All X-ray images (except lateral), CT and CBCT had equal reliability in evaluating medial epicondyle fractures, which contrasts with previous evidence., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)