Complete In Vitro Reconstitution of the Apramycin Biosynthetic Pathway Demonstrates the Unusual Incorporation of a ß-d-Sugar Nucleotide in the Final Glycosylation Step.

Apramycin is a widely used aminoglycoside antibiotic with applications in veterinary medicine. It is composed of a 4-amino-4-deoxy-d-glucose moiety and the pseudodisaccharide aprosamine, which is an adduct of 2-deoxystreptamine and an unusual eight-carbon bicyclic dialdose. Despite its extensive study and relevance to medical practice, the biosynthetic pathway of this complex aminoglycoside nevertheless remains incomplete. Herein, the remaining unknown steps of apramycin biosynthesis are reconstituted in vitro, thereby leading to a comprehensive picture of its biological assembly. In particular, phosphomutase AprJ and nucleotide transferase AprK are found to catalyze the conversion of glucose 6-phosphate to NDP-ß-d-glucose as a critical biosynthetic intermediate. Moreover, the dehydrogenase AprD5 and transaminase AprL are identified as modifying this intermediate via introduction of an amino group at the 4″ position without requiring prior 6″-deoxygenation as is typically encountered in aminosugar biosynthesis. Finally, the glycoside hydrolase family 65 protein AprO is shown to utilize NDP-ß-d-glucose or NDP-4"-amino-4"-deoxy-ß-d-glucose to form the 8',1″-O-glycosidic linkage of saccharocin or apramycin, respectively. As the activated sugar nucleotides in all known natural glycosylation reactions involve either NDP-α-d-hexoses or NDP-ß-l-hexoses, the reported chemistry expands the scope of known biological glycosylation reactions to NDP-ß-d-hexoses, with important implications for the understanding and repurposing of aminoglycoside biosynthesis.

Reconstitution of the Final Steps in the Biosynthesis of Valanimycin Reveals the Origin of Its Characteristic Azoxy Moiety.

Valanimycin is an azoxy-containing natural product isolated from the fermentation broth of Streptomyces viridifaciens MG456-hF10. While the biosynthesis of valanimycin has been partially characterized, how the azoxy group is constructed remains obscure. Herein, the membrane protein VlmO and the putative hydrazine synthetase ForJ from the formycin biosynthetic pathway are demonstrated to catalyze N-N bond formation converting O-(l-seryl)-isobutyl hydroxylamine into N-(isobutylamino)-l-serine. Subsequent installation of the azoxy group is shown to be catalyzed by the non-heme diiron enzyme VlmB in a reaction in which the N-N single bond in the VlmO/ForJ product is oxidized by four electrons to yield the azoxy group. The catalytic cycle of VlmB appears to begin with a resting µ-oxo diferric complex in VlmB, as supported by Mössbauer spectroscopy. This study also identifies N-(isobutylamino)-d-serine as an alternative substrate for VlmB leading to two azoxy regioisomers. The reactions catalyzed by the kinase VlmJ and the lyase VlmK during the final steps of valanimycin biosynthesis are established as well. The biosynthesis of valanimycin was thus fully reconstituted in vitro using the enzymes VlmO/ForJ, VlmB, VlmJ and VlmK. Importantly, the VlmB-catalyzed reaction represents the first example of enzyme-catalyzed azoxy formation and is expected to proceed by an atypical mechanism.

The impact of over-distraction on adjacent segment pathology and cage subsidence in anterior cervical discectomy and fusion.

Over-distraction has been shown to be a risk factor for cage subsidence and postoperative neck pain after anterior cervical discectomy and fusion (ACDF). Biomechanical studies have demonstrated increased adjacent segment intradiscal pressure after ACDF. The purpose of this study is to determine if over-distraction of the index disc has an effect on adjacent segment pathology. A consecutive series of 145 patients who received primary ACDF for cervical degenerative pathologies from January 2010 to December 2017 were retrospectively reviewed. The patients were divided into: (1) Over-distraction group (postoperative-preoperative index disc height ≥ 2 mm), and (2) No-distraction group (postoperative-preoperative index disc height < 2 mm). Outcome measures included radiographic parameters, Japanese Orthopaedic Association (JOA) score, and incidences of cage subsidence, radiological and clinical adjacent segment pathologies (RASP and CASP) were compared between the two groups preoperatively, postoperatively, and at the final follow-up. The two groups were comparable with respect to age, follow-up length, JOA score, incidence of CASP, and radiographic parameters. The Over-distraction group (83 patients; 115 levels) had smaller preoperative index disc height (4.5 vs. 5.2 mm, p < 0.001), but taller postoperative index disc height (7.7 vs. 6.6 mm, p < 0.001) than No-distraction group (62 patients; 90 levels) Furthermore, significantly higher incidences of cage subsidence (47% vs. 31%, p = 0.04) and RASP (any progression: 48% vs. 15%, p < 0.001; progress ≥ 2 grades: 25% vs. 7%, p = 0.001) were observed in the Over-distraction group. The multivariate analysis indicated that over-distraction and multilevel fusion were independent risk factors for RASP. There were no clinical outcome differences between the Over-distraction group and the No-distraction group in ACDF. Over-distraction of the index level of ≥ 2 mm should be avoided because it significantly increases the incidences of RASP and cage subsidence.

Biosynthetic Origin of the Octose Core and Its Mechanism of Assembly during Apramycin Biosynthesis.

Apramycin is an aminoglycoside antibiotic isolated from Streptoalloteichus tenebrarius and S. hindustanus that has found clinical use in veterinary medicine. The apramycin structure is notable for its atypical eight-carbon bicyclic dialdose (octose) moiety. While the apramycin biosynthetic gene cluster (apr) has been identified and several of the encoded genes functionally characterized, how the octose core itself is assembled has remained elusive. Nevertheless, recent gene deletion studies have hinted at an N-acetyl aminosugar being a key precursor to the octose, and this hypothesis is consistent with the additional feeding experiments described in the present report. Moreover, bioinformatic analysis indicates that AprG may be structurally similar to GlcNAc-2-epimerase and hence recognize GlcNAc or a structurally similar substrate suggesting a potential role in octose formation. AprG with an extended N-terminal sequence was therefore expressed, purified, and assayed in vitro demonstrating that it does indeed catalyze a transaldolation reaction between GlcNAc or GalNAc and 6'-oxo-lividamine to afford 7'-N-acetyldemethylaprosamine with the same 6'-R and 7'-S stereochemistry as those observed in the apramycin product. Biosynthesis of the octose core in apramycin thus proceeds in the [6 + 2] manner with GlcNAc or GalNAc as the two-carbon donor, which has not been previously reported for biological octose formation, as well as novel inverting stereochemistry of the transferred fragment. Consequently, AprG appears to be a new transaldolase that lacks any apparent sequence similarity to the currently known aldolases and catalyzes a transaldolation for which there is no established biological precedent.

Changing Fates of the Substrate Radicals Generated in the Active Sites of the B12-Dependent Radical SAM Enzymes OxsB and AlsB.

OxsB is a B12-dependent radical SAM enzyme that catalyzes the oxidative ring contraction of 2'-deoxyadenosine 5'-phosphate to the dehydrogenated, oxetane containing precursor of oxetanocin A phosphate. AlsB is a homologue of OxsB that participates in a similar reaction during the biosynthesis of albucidin. Herein, OxsB and AlsB are shown to also catalyze radical mediated, stereoselective C2'-methylation of 2'-deoxyadenosine monophosphate. This reaction proceeds with inversion of configuration such that the resulting product also possesses a C2' hydrogen atom available for abstraction. However, in contrast to methylation, subsequent rounds of catalysis result in C-C dehydrogenation of the newly added methyl group to yield a 2'-methylidene followed by radical addition of a 5'-deoxyadenosyl moiety to produce a heterodimer. These observations expand the scope of reactions catalyzed by B12-dependent radical SAM enzymes and emphasize the susceptibility of radical intermediates to bifurcation along different reaction pathways even within the highly organized active site of an enzyme.

Two Radical SAM Enzymes Are Necessary and Sufficient for the In Vitro Production of the Oxetane Nucleoside Antiviral Agent Albucidin.

Oxetanocin A and albucidin are two oxetane natural products. While the biosynthesis of oxetanocin A has been described, less is known about albucidin. In this work, the albucidin biosynthetic gene cluster is identified in Streptomyces. Heterologous expression in a nonproducing strain demonstrates that the genes alsA and alsB are necessary and sufficient for albucidin biosynthesis confirming a previous study (Myronovskyi et al. Microorganisms 2020, 8, 237). A two-step construction of albucidin 4'-phosphate from 2'-deoxyadenosine monophosphate (2'-dAMP) is shown to be catalyzed in vitro by the cobalamin dependent radical S-adenosyl-l-methionine (SAM) enzyme AlsB, which catalyzes a ring contraction, and the radical SAM enzyme AlsA, which catalyzes elimination of a one-carbon fragment. Isotope labelling studies show that AlsB catalysis begins with stereospecific H-atom transfer of the C2'-pro-R hydrogen from 2'-dAMP to 5'-deoxyadenosine, and that the eliminated one-carbon fragment originates from C3' of 2'-dAMP.

Simultaneous Hypercorrection of Lowest Instrumented Vertebral Tilt and Main Thoracic Curve is Associated With Progression of Residual Lumbar Curve in Adolescent Idiopathic Scoliosis.

STUDY DESIGN: A retrospective cohort study. OBJECTIVE: To determine radiographic parameters, including the lowest instrumented vertebral (LIV) tilt, related to the postoperative magnitude and progression of residual lumbar curves (LCs) in adolescent idiopathic scoliosis patients who underwent posterior spinal fusion with LIV at or above L1. SUMMARY OF BACKGROUND DATA: Although several guidelines have been proposed for thoracic curve fusion, factors related to the postoperative magnitude and potential progression of unfused LCs remained undetermined. The effect of the LIV tilt on residual LCs is also unclear. MATERIALS AND METHODS: Patients with Lenke type 1 to 4 curves who underwent posterior spinal fusion with LIV at or above L1 with a minimum follow-up period of 2 years were evaluated. Prediction models for residual LCs were developed using multivariate linear regressions with selected radiographic parameters. Subgroup analyses, followed by sensitivity tests, were then performed for variables best predicting the progression of residual LCs. RESULTS: A total of 130 patients were included. Multivariate linear regression analysis showed that the immediate postoperative LIV-tilt angle was associated with the immediate postoperative LCs and the prediction model for residual LCs, with high accuracy ( R =0.93 and 0.77, respectively). Sensitivity tests revealed immediate postoperative LIV-tilt angle <10° and correction rate of main thoracic curve Cobb angle >53% as predictors for progression of residual LCs, and they reached moderate discrimination when combined together as one criterion (odds ratio=16.3, 95% confidence interval=5.3-50.1; sensitivity=89%, specificity=67%, positive predicted value=51%, negative predicted value=94%). CONCLUSION: The current study revealed that LIV tilt, as an operable factor during surgery, is not only a determinant in prediction models showing high correlation with the magnitude of postoperative LCs but a predictor for progression of residual LCs. "Immediate postoperative LIV-tilt angle <10° and correction rate of main thoracic curve Cobb angle >53%," as a united criterion, could serve as a predictor for progression of residual LCs.

Novel MRI-based vertebral bone quality score as a predictor of cage subsidence following transforaminal lumbar interbody fusion.

OBJECTIVE: Decreased bone mineral density as measured by dual-energy x-ray absorptiometry (DEXA) has been reported to be associated with cage subsidence following transforaminal lumbar interbody fusion (TLIF). However, DEXA is not often available or routinely performed before surgery. A novel MRI-based vertebral bone quality (VBQ) score has been developed and reported to be correlated with DEXA T-scores. The authors investigated the ability of the VBQ score to predict cage subsidence and other risk factors associated with this complication. METHODS: In this retrospective study, the authors reviewed the records of patients who had undergone single-level TLIF from March 2014 to October 2015 and had a follow-up of more than 2 years. Cage subsidence was measured as postoperative disc height loss and was graded according to the system proposed by Marchi et al. The MRI-based VBQ score was measured on T1-weighted images. Univariable analysis and multivariable binary logistic regression analysis were performed. Ad hoc analysis with receiver operating characteristic curve analysis was performed to assess the predictive ability of the significant continuous variables. Additional analyses were used to determine the correlations between the VBQ score and T-scores and between the significant continuous variables and the amount of cage subsidence. RESULTS: Among 242 patients eligible for study inclusion, 111 (45.87%) had cage subsidence after the index operation. Multivariable logistic regression analyses demonstrated that an increased VBQ score (OR 14.615 ± 0.377, p < 0.001), decreased depth ratio (OR 0.011 ± 1.796, p = 0.013), and the use of kidney-shaped cages instead of bullet-shaped cages (OR 2.766 ± 0.358, p = 0.008) were associated with increased cage subsidence. The VBQ score was shown to significantly predict cage subsidence with an accuracy of 85.6%. The VBQ score was found to be moderately correlated with DEXA T-scores of the total hip (r = -0.540, p < 0.001) and the lumbar spine (r = -0.546, p < 0.001). The amount of cage subsidence was moderately correlated with the VBQ score (r = 0.512, p < 0.001). CONCLUSIONS: Increased VBQ scores, posteriorly placed cages, and kidney-shaped cages were risk factors for cage subsidence. The VBQ score was shown to be a good predictor of cage subsidence, was moderately correlated with DEXA T-scores for the total hip and lumbar spine, and also had a moderate correlation with the amount of cage subsidence.

Automatic recognition of whole-spine sagittal alignment and curvature analysis through a deep learning technique.

PURPOSE: Artificial intelligence based on deep learning (DL) approaches enables the automatic recognition of anatomic landmarks and subsequent estimation of various spinopelvic parameters. The locations of inflection points (IPs) and apices (APs) in whole-spine lateral radiographs could be mathematically determined by a fully automatic spinal sagittal curvature analysis system. METHODS: We developed a DL model for automatic spinal curvature analysis of whole-spine lateral plain radiographs by using 1800 annotated images of various spinal disease etiologies. The DL model comprised a landmark localizer to detect 25 vertebral landmarks and a numerical algorithm for the generation of an individualized spinal sagittal curvature. The characteristics of the spinal curvature, including the IPs, APs, and curvature angle, could thus be analyzed using mathematical definitions. The localization error of each landmark was calculated from the predictions of 300 test images to evaluate the performance of the landmark localizer. The interrater reliability among a senior orthopedic surgeon, a radiologist, and the DL model was assessed using the intraclass correlation coefficient (ICC). RESULTS: The accuracy of the landmark localizer was within an acceptable range (median error: 1.7-4.1 mm), and the interrater reliabilities between the proposed DL model and each expert were good to excellent (all ICCs > 0.85) for the measurement of spinal curvature characteristics. CONCLUSION: The interrater reliability between the proposed DL model and human experts was good to excellent in predicting the locations of IPs, APs, and curvature angles. Future applications should be explored to validate this system and improve its clinical efficiency.

Automatic prosthetic-parameter estimation from anteroposterior pelvic radiographs after total hip arthroplasty using deep learning-based keypoint detection.

BACKGROUND: X-ray is a necessary tool for post-total hip arthroplasty (THA) check-ups; however, parameter measurements are time-consuming. We proposed a deep learning tool, BKNet that automates localization of landmarks with parameter measurements. METHODS: About 3072 radiographs from 3021 patients who underwent THA at our institute between 2013 and 2017 were used. We employed BKNet to perform landmark localization with parameter measurements in these radiographs. The performance of BKNet was assessed and compared with that of human observers. RESULTS: The 75-percentile cut-off errors were <0.5 cm in all key points. The Bland-Altman methods show the agreement between the predicted and ground truth parameters. Human and BKNet comparison revealed the model could match the repeatability for 7/10 of the parameters. CONCLUSIONS: The accuracy of BKNet is equivalent to that of human observers, and BKNet was able to perform prosthetic-parameter estimation from keypoint detection with superior cost-effectiveness, repeatability, and timesaving compared to human observers.

Improved Characteristics of CdSe/CdS/ZnS Core-Shell Quantum Dots Using an Oleylamine-Modified Process.

CdSe/CdS with ZnS/ZnO shell quantum dots (QDs) are synthesized by a one-pot method with various oleylamine (OLA) contents. The crystal structures of the QDs were analyzed by X-ray diffractometry, which showed ZnS diffraction peaks. It was represented that the ZnS shell was formed on the surface of the CdSe/CdS core. Interestingly, QDs with a high OLA concentration exhibit diffraction peaks of ZnS/ZnO. As a result, the thermal stability of QDs with ZnS/ZnO shells exhibits better performance than those with ZnS shells. In addition, the photoluminescence intensity of QDs with ZnS/ZnO shells shows a relatively slow decay of 7.1% compared with ZnS shells at 85 °C/85% relative humidity aging test for 500 h. These indicate that QDs with different OLA modifications can form ZnS/ZnO shells and have good stability in a harsh environment. The emission wavelength of QDs can be tuned from 505 to 610 nm, suitable for micro-LED display applications.

Effect of Extraction Procedures with Ultrasound and Cellulolytic Enzymes on the Structural and Functional Properties of Citrus grandis Osbeck Seed Mucilage.

The structural and functional properties of Citrus grandis Osbeck (CGO) seed mucilage by different extraction practices, including conventional citrate buffer, ultrasonic-assisted (UAE), enzymatic-assisted extraction (EAE) with cellulase or Celluclast® 1.5 L and various ultrasonic-assisted enzymatic extraction (UAEE) procedures were investigated. It was found that CGO seed from agricultural and processing byproducts is an excellent new source of high methoxyl pectin with quite high intrinsic viscosity (about 108.64 dL/g) and molecular weight (about 1.9 × 106) as compared with other pectin sources. UAEE with Celluclast® 1.5 L enhanced the extraction yield most pronouncedly (about 2.3 times). Moreover, the monosaccharide composition of CGO seed mucilage is least affected by EAE with Celluclast® 1.5 L. In contrast, EAE with cellulase dramatically reduces the galacturonic acid (GalA) content to less than 60 molar%, and increases the glucose (Glc) content pronouncedly (to about 40 molar%), which may be considered as an adverse effect in terms of pectin purity. Though extraction procedures involved with ultrasound and cellulolytic enzymes generally show a decrease in GalA contents, weight average molar mass and intrinsic viscosity, EAE with Celluclast® 1.5 L is least affected, followed by UAE and UAEE with Celluclast® 1.5 L. These features can be leveraged in favor of diversified applications.

Deep learning approach for automatic landmark detection and alignment analysis in whole-spine lateral radiographs.

Human spinal balance assessment relies considerably on sagittal radiographic parameter measurement. Deep learning could be applied for automatic landmark detection and alignment analysis, with mild to moderate standard errors and favourable correlations with manual measurement. In this study, based on 2210 annotated images of various spinal disease aetiologies, we developed deep learning models capable of automatically locating 45 anatomic landmarks and subsequently generating 18 radiographic parameters on a whole-spine lateral radiograph. In the assessment of model performance, the localisation accuracy and learning speed were the highest for landmarks in the cervical area, followed by those in the lumbosacral, thoracic, and femoral areas. All the predicted radiographic parameters were significantly correlated with ground truth values (all p < 0.001). The human and artificial intelligence comparison revealed that the deep learning model was capable of matching the reliability of doctors for 15/18 of the parameters. The proposed automatic alignment analysis system was able to localise spinal anatomic landmarks with high accuracy and to generate various radiographic parameters with favourable correlations with manual measurements.

Mechanistic Investigation of 1,2-Diol Dehydration of Paromamine Catalyzed by the Radical S-Adenosyl-l-methionine Enzyme AprD4.

AprD4 is a radical S-adenosyl-l-methionine (SAM) enzyme catalyzing C3'-deoxygenation of paromamine to form 4'-oxo-lividamine. It is the only 1,2-diol dehydratase in the radical SAM enzyme superfamily that has been identified and characterized in vitro. The AprD4 catalyzed 1,2-diol dehydration is a key step in the biosynthesis of several C3'-deoxy-aminoglycosides. While the regiochemistry of the hydrogen atom abstraction catalyzed by AprD4 has been established, the mechanism of the subsequent chemical transformation remains not fully understood. To investigate the mechanism, several substrate analogues were synthesized and their fates upon incubation with AprD4 were analyzed. The results support a mechanism involving formation of a ketyl radical intermediate followed by direct elimination of the C3'-hydroxyl group rather than that of a gem-diol intermediate generated via 1,2-migration of the C3'-hydroxyl group to C4'. The stereochemistry of hydrogen atom incorporation after radical-mediated dehydration was also established.

Artificial Intelligence for Automatic Measurement of Sagittal Vertical Axis Using ResUNet Framework.

We present an automated method for measuring the sagittal vertical axis (SVA) from lateral radiography of whole spine using a convolutional neural network for keypoint detection (ResUNet) with our improved localization method. The algorithm is robust to various clinical conditions, such as degenerative changes or deformities. The ResUNet was trained and evaluated on 990 standing lateral radiographs taken at Chang Gung Memorial Hospital, Linkou and performs SVA measurement with median absolute error of 1.183 ± 0.166 mm. The 5-mm detection rate of the C7 body and the sacrum are 91% and 87%, respectively. The SVA calculation takes approximately 0.2 s per image. The intra-class correlation coefficient of the SVA estimates between the algorithm and physicians of different years of experience ranges from 0.946 to 0.993, indicating an excellent consistency. The superior performance of the proposed method and its high consistency with physicians proved its usefulness for automatic measurement of SVA in clinical settings.

The correlations between the anchor density and the curve correction of adolescent idiopathic scoliosis surgery.

BACKGROUND: The optimal anchor density in adolescent idiopathic scoliosis (AIS) surgery to achieve good curve correction remains unclear. The purpose of the study is to analyze the correlations between three-dimensional curve correction and anchor density in the pedicle screw-based posterior fusion of AIS. METHODS: One hundred and twenty-seven AIS patients receiving primary posterior fusion with pedicle screw instrumentation were retrospectively reviewed. Anchor density (AD) was defined as the screws number per fused spinal segment. The correlations between three-dimensional curve correction radiographic parameters and anchor density were analyzed with subgroup analysis based on different curve types, curve magnitudes, and curve flexibilities. The differences of curve correction parameters between the low-density (AD ≤1.4), middle-density (1.4 < AD ≤1.7) and high-density (AD > 1.7) groups were also calculated. Independent t-test, analysis of variance (ANOVA), and Pearson's correlation coefficient were used for statistical analysis. RESULTS: There were no correlations between the anchor density and the coronal curve correction or apical vertebral rotation (AVR) correction. In the sagittal plane, mild positive correlations existed between anchor density and thoracic kyphosis correction in all patients (r = 0.27, p = 0.002). Subgroup analysis revealed similar mild positive correlations in Lenke 1 (r = 0.31, p = 0.02), Lenke 1-3 (r = 0.27, p = 0.01), small curves (40°-60°, r = 0.38, p <  0.001), and flexible curves (flexibility > 40%, r = 0.34, p = 0.01). There were no differences between low-density (mean 1.31), middle-density (mean 1.55), and high-density (mean 1.83) in terms of coronal or axial curve correction parameters. Low-density group has longer fused level (mean difference 2.14, p = 0.001) and smaller thoracic kyphosis correction (mean difference 9.25°, p = 0.004) than high-density group. CONCLUSION: In our study, the anchor density was not related to coronal or axial curve corrections. Mild positive correlations with anchor density were found in thoracic kyphosis correction, especially in patients with smaller and flexible curves. Low anchor density with longer fusion level achieves similar curve corrections with middle or high anchor density in adolescent idiopathic scoliosis surgery.

Reliability of the michigan state university (msu) classification of lumbar disc herniation / Confiabilidade da universidade do estado de michigan (msu) classificação da herniação de disco lombar

ABSTRACT Objective: The Michigan State University (MSU) classification of lumbar disc herniation (LDH) is periodically used by various authors to classify disc herniation. We assessed the reliability of this classification system among orthopedic residents at our institute. Methods: Fifty T2 axial-cut magnetic resonance images (MRI) corresponding to the level of maximal disc herniation from patients diagnosed with a single LDH were selected and distributed to six orthopedic residents. All six residents gave a specific rating for each image based on the MSU classification; in addition, three residents gave ratings on two different occasions. The degree of agreement among residents was analyzed by calculating inter-observer and intra-observer reliability using the Kappa statistic. Results: The inter-observer reliability among the six residents calculated as the Fleiss' Kappa was 0.422, which indicates moderate reliability. The intra-observer reliability of three selected residents calculated by Cohen's Kappa was 0.750, 0.772, and 0.859, which indicates substantial to almost perfect reliability. Variations in ratings were frequent in images portraying a broad-based disc herniation with spinal canal stenosis. Conclusion: Our findings demonstrate moderate homogeneity of ratings given by residents; however, test-retest results proved the ratings to be consistent. Level of Evidence II, Diagnostic studies - investigating a diagnostic examination.

RESUMO Objetivo: A classificação da hérnia de disco lombar (LDH) da Michigan State University (MSU) é usada periodicamente por vários autores para classificar as hérnias discais. Pretendemos avaliar a confiabilidade deste sistema de classificação entre os residentes de ortopedia em nosso instituto. Métodos: Cinqüenta imagens de RM axial do corte T2 correspondendo ao nível de hérnia discal máxima de pacientes que foram diagnosticados com uma única LDH foram selecionadas e distribuídas para seis residentes ortopédicos. Todos os seis residentes deram uma classificação específica para cada imagem com base na classificação MSU; Além disso, três residentes deram notas em duas ocasiões diferentes. O grau de concordância entre os residentes foi analisado calculando-se a confiabilidade interobservador e intraobservador pela estatística Kappa. Resultados: Descobrimos que a confiabilidade interobservador entre seis residentes, calculando o Kappa de Fleiss, foi de 0,422; isso indica confiabilidade moderada. No entanto, a confiabilidade intra-observador de três residentes selecionados mostrou-se substancial (Kappa de Cohen = 0,750, 0,772 e 0,859 em três residentes, respectivamente). Variações na observação foram frequentes se houvesse hérnia discal ampla com estenose do canal vertebral. Conclusão: Nossos achados demonstram homogeneidade moderada das avaliações dadas pelos residentes; no entanto, teste-reteste provou que as classificações eram consistentes. Nível de Evidencia II, Estudos diagnósticos - investigação de um exame para diagnóstico.

Is Convex Derotation Equally Effective as Concave Derotation for Achieving Adequate Correction of Selective Lenke's Type- 1 Scoliosis?

BACKGROUND: Correcting the scoliosis and stabilizing the spine in the corrected position is the basis of treatment for adolescent idiopathic scoliosis (AIS). Spinal instrumentation and derotation are the principle steps of surgery for any type of AIS. A perspicuous understanding needs to be attained regarding derotation maneuvers in practice; therefore, we intend to compare radiological outcomes following concave and convex rod derotation maneuvers to analyze their efficacy to correct selective Lenke's Type-1 scoliosis. MATERIALS AND METHODS: Retrospectively, 88 patients with Lenke's Type-1 scoliosis who were operated with selective thoracic instrumentation were divided into two groups depending on the derotation side. Preoperative radiographs were analyzed for curve angles, thoracic apical vertebral translation, apical vertebral rotation, and coronal/sagittal balance. Postoperative and followup assessment was focused on curve correction. Correction rate of main thoracic (MT) curve and its corresponding loss of correction at final followup are calculated. RESULTS: Concave group (n = 40; age 13.8 ± 1.9) and the convex group (n = 48; Age 14.3 ± 2.4) showed similar demographic characteristics. Postoperative and followup parameters showed no significant difference. Correction rate of MT curve between both groups (concave group = 69.2 ± 10.5%; convex group = 66 ± 12.8%; P = 0.20) was similar. There was minimal loss of correction at final followup among both groups (concave group = 2.2° ±5.4°; Convex group = 1.5° ± 4.8°; P = 0.52). CONCLUSION: The study results showed similar sustained satisfactory correction of flexible Lenke's type 1 scoliotic curves irrespective of the derotation maneuver used. Adequate correction, thereby restoring balance was predominantly perceived among the entire sample. Hence, convex derotation can be considered equally effective as that of concave derotation for achieving adequate correction of selective Lenke's Type-1 scoliosis.

RELIABILITY OF THE MICHIGAN STATE UNIVERSITY (MSU) CLASSIFICATION OF LUMBAR DISC HERNIATION.

OBJECTIVE: The Michigan State University (MSU) classification of lumbar disc herniation (LDH) is periodically used by various authors to classify disc herniation. We assessed the reliability of this classification system among orthopedic residents at our institute. METHODS: Fifty T2 axial-cut magnetic resonance images (MRI) corresponding to the level of maximal disc herniation from patients diagnosed with a single LDH were selected and distributed to six orthopedic residents. All six residents gave a specific rating for each image based on the MSU classification; in addition, three residents gave ratings on two different occasions. The degree of agreement among residents was analyzed by calculating inter-observer and intra-observer reliability using the Kappa statistic. RESULTS: The inter-observer reliability among the six residents calculated as the Fleiss' Kappa was 0.422, which indicates moderate reliability. The intra-observer reliability of three selected residents calculated by Cohen's Kappa was 0.750, 0.772, and 0.859, which indicates substantial to almost perfect reliability. Variations in ratings were frequent in images portraying a broad-based disc herniation with spinal canal stenosis. CONCLUSION: Our findings demonstrate moderate homogeneity of ratings given by residents; however, test-retest results proved the ratings to be consistent. Level of Evidence II, Diagnostic studies - investigating a diagnostic examination.

OBJETIVO: A classificação da hérnia de disco lombar (LDH) da Michigan State University (MSU) é usada periodicamente por vários autores para classificar as hérnias discais. Pretendemos avaliar a confiabilidade deste sistema de classificação entre os residentes de ortopedia em nosso instituto. MÉTODOS: Cinqüenta imagens de RM axial do corte T2 correspondendo ao nível de hérnia discal máxima de pacientes que foram diagnosticados com uma única LDH foram selecionadas e distribuídas para seis residentes ortopédicos. Todos os seis residentes deram uma classificação específica para cada imagem com base na classificação MSU; Além disso, três residentes deram notas em duas ocasiões diferentes. O grau de concordância entre os residentes foi analisado calculando-se a confiabilidade interobservador e intraobservador pela estatística Kappa. RESULTADOS: Descobrimos que a confiabilidade interobservador entre seis residentes, calculando o Kappa de Fleiss, foi de 0,422; isso indica confiabilidade moderada. No entanto, a confiabilidade intra-observador de três residentes selecionados mostrou-se substancial (Kappa de Cohen = 0,750, 0,772 e 0,859 em três residentes, respectivamente). Variações na observação foram frequentes se houvesse hérnia discal ampla com estenose do canal vertebral. CONCLUSÃO: Nossos achados demonstram homogeneidade moderada das avaliações dadas pelos residentes; no entanto, teste-reteste provou que as classificações eram consistentes. Nível de Evidencia II, Estudos diagnósticos - investigação de um exame para diagnóstico.

Targeting Tumor Associated Phosphatidylserine with New Zinc Dipicolylamine-Based Drug Conjugates.

A series of zinc(II) dipicolylamine (ZnDPA)-based drug conjugates have been synthesized to probe the potential of phosphatidylserine (PS) as a new antigen for small molecule drug conjugate (SMDC) development. Using in vitro cytotoxicity and plasma stability studies, PS-binding assay, in vivo pharmacokinetic studies, and maximum tolerated dose profiles, we provided a roadmap and the key parameters required for the development of the ZnDPA based drug conjugate. In particular, conjugate 24 induced tumor regression in the COLO 205 xenograft model and exhibited a more potent antitumor effect with a 70% reduction of cytotoxic payload compared to that of the marketed irinotecan when dosed at the same regimen. In addition to the validation of PS as an effective pharmacodelivery target for SMDC, our work also provided the foundation that, if applicable, a variety of therapeutic agents could be conjugated in the same manner to treat other PS-associated diseases.