Vitamin D as an intervention for improving quadriceps muscle strength in patients after anterior cruciate ligament reconstruction: study protocol for a randomized double-blinded, placebo-controlled clinical trial

BACKGROUND

The goal of anterior cruciate ligament reconstruction (ACLR) is to restore the preinjury level of knee function to return to play (RTP). However, even after completing the rehabilitation programme, some patients may have persistent quadriceps muscle weakness affecting knee function which ultimately leads to a failure in returning to play. Vitamin D has been long recognized for its musculoskeletal effects. Vitamin D deficiency may impair muscle strength recovery after ACLR. Correcting vitamin D levels may improve muscle strength.

METHODS

This is a double-blinded, randomized controlled trial to investigate the effects of vitamin D supplementation during the post-operative period on quadriceps muscle strength in anterior cruciate ligament (ACL)-injured patients. Patients aged 18-50 with serum vitamin D < 20 ng/ml, unilateral ACL injury, > 90% deficit in total quadriceps muscle volume on the involved leg compared with uninvolved leg, Tegner score 7 + , and no previous knee injury/surgery will be recruited. To assess patient improvement, we will perform isokinetic and isometric muscle assessments, ultrasound imaging for quadriceps thickness, self-reported outcomes, KT-1000 for knee laxity, biomechanical analysis, and Xtreme CT for bone mineral density. To investigate the effect of vitamin D status on quadriceps strength, blood serum samples will be taken before and after intervention.

DISCUSSION

Patients with low vitamin D levels had greater quadriceps fibre cross-sectional area loss and impaired muscle strength recovery after ACL. The proposed study will provide scientific support for using vitamin D supplementation to improve quadriceps strength recovery after ACLR.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05174611. Registered on 28 November 2021.

Serum vitamin D insufficiency is correlated with quadriceps neuromuscular functions in patients with anterior cruciate ligament injury: A preliminary study

Background

This study aimed to investigate the correlations of serum vitamin D insufficiency with quadriceps neuromuscular function in patients with anterior cruciate ligament (ACL) injury.

Methods

A cross-sectional study was conducted. Eighteen patients with a primary, unilateral ACL injury who had insufficient serum vitamin D concentrations (<30 ng/ml) were recruited for the study. Bilateral quadriceps neuromuscular function, including maximal strength, the speed of rapid contraction, and inhibition, were measured on an isokinetic dynamometer with the hip and the knee joint flexion at 90° and 45°, respectively. Quadriceps strength was measured by maximal voluntary isometric contractions (MVIC); the speed of rapid contraction was quantified by the rate of torque development (RTD), which was divided into the early (RTD0-50) and the late phase (RTD100-200); quadriceps inhibition was quantified by the central activation ratio (CAR). Serum vitamin D concentration was quantitatively determined by serum 25(OH)D concentration measured by the 25(OH)D ELISA kit. The Spearman rank correlation analysis was used to examine the correlation between the vitamin D concentration and bilateral quadriceps MVIC, RTD0-50, RTD100-200, and CAR, respectively.

Results

The results of Spearman rank correlation analyses showed that the serum 25(OH)D concentration was significantly correlated with bilateral quadriceps MVIC (injured: r = 0.574, p = 0.013; uninjured: r = 0.650, p = 0.003) and RTD0-50 (r = 0.651, p = 0.003), and CAR (r = 0.662, p = 0.003) on the uninjured limb. However, no significant correlations were found between the serum 25(OH)D concentration and the other outcomes.

Conclusions

The serum vitamin D concentration correlates with quadriceps neuromuscular function in patients with ACL injury who had vitamin D insufficiency.

Surgical accuracy of image-free versus image-based robotic-assisted total knee arthroplasty

BACKGROUND

This study investigated the accuracy in achieving proper lower limb alignment and component positions after total knee replacement (TKR) with image-free and image-based robotic-assisted TKR.

METHODS

A total of 129 patients (166 knees) suffering from end-stage knee arthritis who underwent TKA operated by robotic-assisted surgery between the years 2018 and mid-2021 were recruited. Radiological outcomes were compared between image-free and image-based robotic-assisted surgical systems.

RESULTS

There were significant differences between the two robotic systems when comparing the mean planned component alignment and the mean measured alignment on radiographs, in which the image-free robotic-assisted system was more varus, whereas the image-based robotic-assisted system was more valgus for both the mean femoral and tibial component coronal alignment (p < 0.001). For tibial component sagittal alignment, the image-based group had a larger deviation from the planned posterior slope (p < 0.001).

CONCLUSION

Image-free and image-based robotic assisted TKR had differing accuracy in femoral and tibial alignment.

Assessments of early patellofemoral joint osteoarthritis features after anterior cruciate ligament reconstruction: a cross-sectional study

BACKGROUND

Persistent anterior knee pain and subsequent patellofemoral joint (PFJ) osteoarthritis (OA) are common symptoms after anterior cruciate ligament reconstruction (ACLR). Quadriceps weakness and atrophy is also common after ACLR. This can be contributed by arthrogenic muscle inhibition and disuse, caused by joint swelling, pain, and inflammation after surgery. With quadriceps atrophy and weakness are associated with PFJ pain, this can cause further disuse exacerbating muscle atrophy. Herein, this study aims to identify early changes in musculoskeletal, functional and quality of health parameters for knee OA after 5 years of ACLR.

METHODS

Patients treated with arthroscopically assisted single-bundle ACLR using hamstrings graft for more than 5 years were identified and recruited from our clinic registry. Those with persistent anterior knee pain were invited back for our follow-up study. For all participants, basic clinical demography and standard knee X-ray were taken. Likewise, clinical history, symptomatology, and physical examination were performed to confirm isolated PFJ pain. Outcome measures including leg quadriceps quality using ultrasound, functional performance using pressure mat and pain using self-reported questionnaires (KOOS, Kujala and IKDC) were assessed. Interobserver reproducibility was assessed by two reviewers.

RESULTS

A total of 19 patients with unilateral injury who had undergone ACLR 5-years ago with persistent anterior knee pain participated in this present study. Toward the muscle quality, thinner vastus medialis and more stiffness in vastus lateralis were found in post-ACLR knees (p < 0.05). Functionally, patients with more anterior knee pain tended to shift more of their body weight towards the non-injured limb with increasing knee flexion. In accordance, rectus femoris muscle stiffness in the ACLR knee was significantly correlated with pain (p < 0.05).

CONCLUSION

In this study, it was found that patients having higher degree of anterior knee pain were associated with higher vastus medialis muscle stiffness and thinner vastus lateralis muscle thickness. Similarly, patients with more anterior knee pain tended to shift more of their body weight towards the non-injured limb leading to an abnormal PFJ loading. Taken together, this current study helped to indicate that persistent quadriceps muscle weakness is potential contributing factor to the early development of PFJ pain.

Melatonin in Endometriosis: Mechanistic Understanding and Clinical Insight

Endometriosis is defined as the development of endometrial glands and stroma outside the uterine cavity. Pathophysiology of this disease includes abnormal hormone profiles, cell survival, migration, invasion, angiogenesis, oxidative stress, immunology, and inflammation. Melatonin is a neuroendocrine hormone that is synthesized and released primarily at night from the mammalian pineal gland. Increasing evidence has revealed that melatonin can be synthesized and secreted from multiple extra-pineal tissues where it regulates immune response, inflammation, and angiogenesis locally. Melatonin receptors are expressed in the uterus, and the therapeutic effects of melatonin on endometriosis and other reproductive disorders have been reported. In this review, key information related to the metabolism of melatonin and its biological effects is summarized. Furthermore, the latest in vitro and in vivo findings are highlighted to evaluate the pleiotropic functions of melatonin, as well as to summarize its physiological and pathological effects and treatment potential in endometriosis. Moreover, the pharmacological and therapeutic benefits derived from the administration of exogenous melatonin on reproductive system-related disease are discussed to support the potential of melatonin supplements toward the development of endometriosis. More clinical trials are needed to confirm its therapeutic effects and safety.

Effect of pulsed electromagnetic field as an intervention for patients with quadriceps weakness after anterior cruciate ligament reconstruction: a double-blinded, randomized-controlled trial

Background

The ultimate goal of anterior cruciate ligament reconstructions (ACLR) is to fulfil the return-to-play (RTP) criteria. Quadriceps muscle strength is one of the key determinants for a patient’s successful return-to-play after ACLR. Quadriceps muscle atrophy can persist beyond the completion of the rehabilitation program in almost half the patients and the reason behind this is still unknown. There are emerging evidences showing that pulsed electromagnetic field (PEMF) can modulate mitochondrial activities for muscle gain. PEMF exposure on top of regular exercise training may promote muscle regeneration and tissue healing.

Methods

This is a double-blinded, randomized controlled trial to investigate the effects of PEMF treatment during the postoperative period on quadriceps muscle strength in ACL injured patient. Adult patients (aged 18–30) with a unilateral ACL injury, total quadriceps muscle volume is equal or more than 7% deficit on involved leg compared with uninvolved leg, sporting injury with a Tegner score of 7+, and both knees without a history of injury/prior surgery will be recruited. To estimate the improvement of patients, isokinetic muscle assessment, ultrasound imaging and MRI for quadriceps muscle thickness, self-reported outcomes with questionnaires, KT-1000 for knee laxity and biomechanical analysis, and Xtreme CT for bone mineral density will be performed. To investigate the mechanism of PEMF therapy on increasing quadriceps strength, samples of blood serum will be drawn before and after intervention.

Discussion

This is the first trial evaluating the effects of PEMF on quadriceps muscle recovery after ACLR. The proposed study addresses a huge research gap by evaluating practical use of PEMF as part of rehabilitation. The proposed study will provide much needed scientific support in the use of this noninvasive treatment modality to facilitate recovery of quadriceps strength after PEMF.

Trial registration

ClinicalTrials.gov NCT05184023. Registered on 5 January 2022

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06674-2.

Simultaneous Measurement of Patellofemoral Joint Kinematics and Contact Mechanics in Intact Knees: A Cadaveric Study

Objective

Patellofemoral kinematics and contact mechanics are important measurements for the assessment of patellofemoral joint (PFJ) problems. Simultaneously measuring PFJ contact pressures and kinematics is a challenging task. The purpose of this study was to simultaneously measure the kinematics and mean/peak contact pressures in the PFJs of cadaveric knees.

Methods

This was a comparative study performed on fresh cadaveric knees. The kinematic data was acquired for nine cadaveric knees using an optical tracking system. Data about the contact pressure and contact area in the PFJ was obtained at knee flexion angles of 0°, 30°, 60°, 90°, and 120° using a pressure sensor. Intraclass correlation coefficients (ICCs) and minimal detectable differences (MDDs) of six degrees of freedom (6 DOF) in the PFJs were calculated. ICCs and the MDDs of contact pressure, peak pressure, and contact area in the PFJs were also analyzed. We also compared the kinematics of the cadaveric knees before and after the insertion of the pressure sensor.

Results

All ICC values of 6 DOF in the PFJs were found to be greater than or equal to 0.924. Regarding medial–lateral rotation, the patellar showed a simplified movement pattern that demonstrated progressive lateral rotation of 4.8° ± 3.4° at 120° of knee flexion. While for patellar tilting, the patella showed medial tilting that peaked at 7.2 ± 2.5° at 30° of knee flexion. Whereas no significant differences in PFJ kinematics were found between with and without the placement of the pressure sensor at all knee flexions (P > 0.05). Most of the ICC values for contact pressure, peak contact pressure, and contact area ranged from 0.8 to 0.9. The MDDs for rotational displacement were 0.9° and 0.6 mm for translational displacement. No statistical differences in patellar kinematics were found before and after the insertion of the pressure sensor.

Conclusions

The setup in the present study enables researchers to simultaneously and synchronously collect real‐time PFJ kinematics and tibiofemoral joint (TFJ) biomechanical kinematic data with high reliability. The low MDDs enabled the researchers to obtain an accurate interpretation of the kinematic and contact mechanics measurement using the experimental setting used in the present study.

Green Tea Epigallocatechin-3-Gallate Regulates Autophagy in Male and Female Reproductive Cancer

With a rich abundance of natural polyphenols, green tea has become one of the most popular and healthiest nonalcoholic beverages being consumed worldwide. Epigallocatechin-3-gallate (EGCG) is the predominant catechin found in green tea, which has been shown to promote numerous health benefits, including metabolic regulation, antioxidant, anti-inflammatory, and anticancer. Clinical studies have also shown the inhibitory effects of EGCG on cancers of the male and female reproductive system, including ovarian, cervical, endometrial, breast, testicular, and prostate cancers. Autophagy is a natural, self-degradation process that serves important functions in both tumor suppression and tumor cell survival. Naturally derived products have the potential to be an effective and safe alternative in balancing autophagy and maintaining homeostasis during tumor development. Although EGCG has been shown to play a critical role in the suppression of multiple cancers, its role as autophagy modulator in cancers of the male and female reproductive system remains to be fully discussed. Herein, we aim to provide an overview of the current knowledge of EGCG in targeting autophagy and its related signaling mechanism in reproductive cancers. Effects of EGCG on regulating autophagy toward reproductive cancers as a single therapy or cotreatment with other chemotherapies will be reviewed and compared. Additionally, the underlying mechanisms and crosstalk of EGCG between autophagy and other cellular processes, such as reactive oxidative stress, ER stress, angiogenesis, and apoptosis, will be summarized. The present review will help to shed light on the significance of green tea as a potential therapeutic treatment for reproductive cancers through regulating autophagy.

Risk of surgery and epidemiological profile of athletes presenting to a single sports injury clinic in Hong Kong

Background

Although participation in sports and exercise is promoted widely due to its health benefits, sports-related injuries can also be a detriment to an individual's health and a burden for the healthcare system. Herein, the aim of this study is to provide a comprehensive review on the epidemiological profile and the risk for surgery of athletes presented to a sports injuries clinic in Hong Kong.

Methods

A total of 566 patients attending the sports injuries clinic at a local hospital between October 2017 and September 2018 were reviewed. Only 271 patients sustaining injuries from sports activities were included. These patients attended a survey-based data collection session, which recorded their demographic, injury site, events leading to injury, exercise details (type, level-of-play, frequency, experience), and functional score according to the injury site.

Results

The highest proportion of injuries was observed in amateur athletes (45.4%) than in recreational (28.8%) and professional (25.8%). Those patients aged between 18–29 years old (50.2%) had the most injuries. Both soccer (25.1%) and basketball (25.1%) were the two most common sports to incurred injuries. Whereas, the lower extremities being the most common injured sites. Based on our logistic model, athletes with less experience were more prone to required surgeries with injuries in the lower extremities.

Conclusion

Preventive measures should be targeted at less experience athletes, focusing on strengthening the knee region, to reduce sports-related injuries and surgeries. Importantly, this study demonstrates the need to further identify factors to develop effective sports injury prevention programmes for tailoring athletes at different levels-of-play.

The role of paraspinal muscle degeneration in coronal imbalance in patients with degenerative scoliosis

Background

Coronal imbalance in degenerative scoliosis is common and is highly correlated with health-related quality of life. Paraspinal muscle is critical to spine stability, but little is known about its contribution to coronal imbalance in degenerative scoliosis. This study aims to investigate the relationship between paraspinal muscle (PSM) degeneration and coronal imbalance in patients with degenerative scoliosis (DS).

Methods

This is a retrospective cohort study. A total of 117 patients with DS were retrospectively reviewed. Parameters of PSM (bilateral cross-sectional area, CSA; fat infiltration rate, FI%) at the apical disc and adjacent levels were quantitatively evaluated using MRI. Standing whole-spine radiograph was used to evaluate the coronal (Cobb angle, CA; coronal balance distance, CBD) and sagittal (thoracic kyphosis, TK; lumbar lordosis, LL; sagittal vertical axis, SVA) parameters. Patients were divided into 3 groups: coronal balanced (Type A), coronal imbalanced shifting to concavity (Type B), and coronal imbalanced shifting to convexity (Type C).

Results

Based on our criteria, 56 patients were assigned to Type A, 34 patients to Type B, and 27 patients to Type C. There was no significant difference on the sagittal profiles and CSA between the groups. However, Type A showed significantly lower FI% than Type B and Type C on both concavity and convexity (Concave side: Type A vs. Type B vs. Type C, 30.8±8.1 vs. 45.1±7.7 vs. 38.7±12.5, P=0.001; Convex side: Type A vs. Type B vs. Type C, 32.6±10.9 vs. 46.3±7.3 vs. 40.7±11.8, P=0.004). Specifically, Cobb angle was negatively correlated with CSA, mainly at convexity (R=−0.415, P=0.008). Similarly, the increase of CBD significantly correlated with FI% at concavity (R=0.491, P=0.001) and convexity (R=0.354, P=0.025).

Conclusions

DS patients with coronal imbalance demonstrated a worse PSM degeneration when compared with those without coronal imbalance. Besides, PSM degeneration strongly correlated with coronal imbalance, which implies that PSM degeneration may contribute to the coronal imbalance in patients with DS.

Injury epidemiology of Ultimate Frisbee in Hong Kong

Background

Ultimate Frisbee is a non-contact, self-refereed team sport that is rapidly gaining popularity in Hong Kong. As it is a physically demanding competition, it can result in substantial injury risk. However, the injury epidemiology data in Hong Kong remains lacking. The aim of this study is to identify and analyse the injury prevalence and risk factors for Ultimate Frisbee players in Hong Kong.

Methods

Online self-reported surveys were collected from participants through the Hong Kong Flying Disc Federation for the 2019 season. Data was collected on injury type, location, nature, severity and onset. Injury incidence rates (IRs) were calculated as injuries per 1000 h of athlete-exposures (AEs). Incidence rate ratios were determined to compare IRs with 95% confidence intervals, which were used to calculate differences. In addition, analysis on IR will be made on comparing between training and tournament.

Results

Response rate of 75.6% was achieved, of which 59 entries were included for analysis. We observed 54 injuries over 9412 AEs for a total IR of 5.74 per 1000 h of AEs. The injury prevalence is 62.7%, with both men and women having similar incidence (IRR = 1.161, 95% CI = 0.63, 2.14, p = 0.63). The most common injuries were in the lower limb (61.1%). Cutting was the most frequent injury mechanism (23.7%). The risk of injury during training is 3 times less compared to during tournament (IRR = 0.03, 95% CI = 0.18, 0.60, p < 0.01).

Conclusion

Our preliminary findings provide evidence that majority of Ultimate injuries in Hong Kong players involved the lower extremity with injuries occurring more in tournaments than training. This study is an important first step to provide the groundwork for tailoring prevention strategies to minimize injuries in Ultimate Frisbee.

Posterior Tibial Loading Results in Significant Increase of Peak Contact Pressure in the Patellofemoral Joint During Anterior Cruciate Ligament Reconstruction: A Cadaveric Study

BACKGROUND

Inappropriate posterior tibial loading and initial graft tension during anterior cruciate ligament (ACL) reconstruction may cause altered patellofemoral joint (PFJ) contact mechanics, potentially resulting in pain and joint degeneration.

HYPOTHESIS

PFJ contact pressure would increase with the increases in posterior tibial loading and graft tension during ACL reconstruction.

STUDY DESIGN

Controlled laboratory study.

METHODS

Nine fresh-frozen, nonpaired human cadaveric knees were tested in a customized jig from 0° to 120° of knee flexion. First, the knee was tested in the ACL-intact state. Second, reconstruction of the ACLs using different posterior tibial loadings and graft tensions were performed. The posterior tibial loading was evaluated at 2 levels: 33.5 and 67 N. Graft tension was assessed at 3 levels: low tension (20 N), medium tension (60 N), and high tension (80 N). Maximum values of peak contact pressure in the medial and lateral patellar facets were compared between ACL-intact and ACL-reconstructed knees. The PFJ kinematics between ACL-intact knees and ACL-reconstructed knees were compared during knee flexion at 30°, 60°, 90°, and 120°.

RESULTS

Reconstruction of ACLs with both low and high posterior tibial loading resulted in significant increases of peak contact pressure in the medial (range of differences, 0.46-0.92 MPa; P < .05) and lateral (range of differences, 0.51-0.83 MPa; P < .05) PFJ compared with the ACL-intact condition. However, no significant differences in PFJ kinematics were identified between ACL-reconstructed knees and ACL-intact knees. In ACL-reconstructed knees, it was found that a high posterior tibial loading resulted in high peak contact pressure on the medial patellar side (range of differences, 0.37-0.46 MPa; P < .05). No significant difference in peak contact pressure was observed among the differing graft tensions.

CONCLUSION

In this cadaveric model, ACL reconstruction resulted in significant increases of peak contact pressure in the PFJ facet when compared with the ACL-intact condition. A high posterior tibial loading can lead to high medial PFJ peak contact pressure. Graft tension was found to not significantly affect PFJ contact pressure during ACL reconstruction.

CLINICAL RELEVANCE

An excessive posterior tibial loading during ACL reconstruction resulted in increased PFJ contact pressures at time of surgery. These data suggest that a low posterior tibial loading might be preferred during ACL reconstruction surgery to reduce the PFJ contact pressure close to that of the ACL-intact condition.

Abnormal Osteoblastic Response to Leptin in Patients with Adolescent Idiopathic Scoliosis

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional structural deformity of the spine with unknown etiology. Although leptin has been postulated as one of the etiologic factors in AIS, its effects on osteoblastic activity remain unknown. Herein, we conducted this study to investigate whether there are abnormal functional responses to leptin and abnormal expression of leptin receptor in AIS osteoblasts. In vitro assays were performed with osteoblasts isolated from 12 severe AIS girls and 6 non-AIS controls. The osteoblasts were exposed to different concentrations of leptin (0, 10, 100, 1000 ng/mL). The effects of leptin on cell proliferation, differentiation and mineralization were determined. Protein expressions of leptin receptor (LEP-R) under basal and osteogenic conditions were also evaluated by Western blot. Our results showed that leptin significantly stimulated osteoblasts from non-AIS subjects to proliferate, differentiate and mineralized. However, in the AIS group, the stimulatory effects of leptin on cell proliferation, differentiation, and mineralization were not observed. In addition, no statistically significant difference in the expression of leptin receptor under both basal and osteogenic conditions was found between AIS and control group. In conclusion, these findings might help to explain the low bone mass and deranged bone quality that is clinically associated with AIS girls.

Abstract 1232: Paclitaxel induces immunogenic cell death in ovarian cancer via TLR4-independent and dependent pathways

Immunogenic cell death refers to a phenomenon in which some of the cytotoxic chemotherapeutics kills the tumor cells and induces these dying cells to be immunogenic. The aim of this study is to investigate if the standard-of-care chemotherapy (carboplatin and paclitaxel) induces immunogenic cell death in ovarian cancer. We found that paclitaxel, but not carboplatin, induces multiple molecular determinants of immunogenic cell death (namely calreticulin exposure, ATP secretion, HMGB1 release, ANXA1 expression, and upregulation of CXCL10) in ID8 mouse ovarian cancer cells. By tumor vaccination assay in immunocompetent syngeneic mice, our results showed paclitaxel induces immunogenic cell death in the mice with ID8 ovarian tumor. Since toll-like receptor 4 (TLR4) is a receptor for paclitaxel, we generated isogenic derivatives of ID8 cells with Tlr4 knockout (KO) to investigate if paclitaxel induces immunogenic cell death is dependent on TLR4. Our results showed that the paclitaxel-induced molecular determinants of immunogenic cell death were diminished in the TLR4 KO clones when compared to wild-type controls. Moreover, the tumor vaccination assay showed that paclitaxel was not able to induce immunogenic cell death in mice with ovarian tumor with TLR4 KO. These results indicated that the paclitaxel requires TLR4 to induce immunogenic cell death. To explore the mechanisms of how paclitaxel induces immunogenic cell death through TLR4, we investigated the activation of PERK and phosphorylation of eIF2a in ER stress since they are the first two enumerate elements of the pathways that mediated calreticulin exposure in response to immunogenic anticancer chemotherapeutics. Our results, however, showed that paclitaxel induces activation of PERK and phosphorylation of eIF2a in ovarian cancer cells is independent on TLR4. We then investigate if paclitaxel induces SNARE-dependent exocytosis in mouse ovarian cancer cells because SNARE-dependent exocytosis is the final step of the pathways that mediated calreticulin exposure in immunogenic cell death. Our results showed that paclitaxel induces SNARE-dependent exocytosis of ATP-containing vesicles in mouse ovarian cancer cells via TLR4-mediated IKK2 activation. In summary, our results showed that paclitaxel induces immunogenic cell death in ovarian cancer through TLR4-independent and dependent pathways, in which paclitaxel-induced exocytosis is essential for the release of multiple molecular determinants of immunogenic cell death. Our results provide new evidence that the antitumor effect of paclitaxel occurs in part via activation of an immune response against cancer by inducing immunogenic cell death and provide a rationale for a new combination of paclitaxel and immunotherapies as an anticancer treatment.

Citation Format: Tat-San Lau, Loucia Kit-Ying Chan, Gene Chi-Wai Man, Joseph Kwong. Paclitaxel induces immunogenic cell death in ovarian cancer via TLR4-independent and dependent pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1232.

Abnormal melatonin receptor 1B expression in osteoblasts from girls with adolescent idiopathic scoliosis

Melatonin signaling dysfunction has been associated with the etiology of adolescent idiopathic scoliosis (AIS). Genetic analysis has also associated the occurrence of AIS with the MT2 gene. Thus, we determined whether there is abnormality in the protein expression of melatonin receptors (MT) in AIS osteoblasts. In this study, we recruited 11 girls with severe AIS and eight normal subjects for intraoperative bone biopsies. MT1 and MT2 receptor protein expressions in the isolated osteoblasts were detected. Also, cell proliferation assay using different melatonin concentrations (0, 10(-9), 10(-5), 10(-4) m) was carried out. The results showed that both MT1 and MT2 receptors are expressed in osteoblasts of the controls. While MT1 receptors were expressed in osteoblasts of all AIS subjects, osteoblasts of only 7 of 11 AIS showed expression of MT2 receptors. Melatonin stimulated control osteoblasts to proliferate. However, proliferation of AIS osteoblasts without expression of MT2 receptor, after treatment with melatonin, was minimal when compared with control and AIS osteoblasts with MT2 receptor expression. The proliferation of AIS osteoblasts with MT2 receptor was greater than those without. This is the first report demonstrating a difference between AIS and normal osteoblasts in the protein expression of MT2 receptor. The results suggest that there is a possible functional effect of MT2 receptor on osteoblast proliferation. AIS osteoblasts without expression of MT2 receptor showed the lowest percentage of viable cells after melatonin treatment. This possibly indicates the modulating role of melatonin through MT2 receptor on the proliferation of osteoblasts.

Color quantification for evaluation of stained tissues

The objective evaluation of the color and shade in stained images remains unsolved and is frequently and extensively encountered in biomedical studies. Most of the evaluations on the color and shade in the stained images are currently performed by subjective grading, which is prone to be affected by inter-reader variation. This paper introduces a novel approach to automatically quantify the color and shade in the stained histological image based on its similarity map in the CIELAB color space with respect to a user specified reference color. The proposed algorithm was applied on three datasets, i.e., a phantom image, the Prussian blue staining of human osteosarcoma cell culture, and histological sections of the Prussian blue stained rat kidney, liver and spleen. The result shows that our method is able to represent the color and shade as a numerical value that correlated well with human perception.

Abnormal proliferation and differentiation of osteoblasts from girls with adolescent idiopathic scoliosis to melatonin

Melatonin deficiency has been postulated as an etiologic factors in adolescent idiopathic scoliosis (AIS). In previous studies, melatonin was shown to regulate skeletal growth and bone formation in both humans and rats. Although it remains controversial whether there are differences in serum melatonin level between AIS and control subjects, melatonin signaling pathway dysfunction in osteoblasts has been reported in patients with AIS. Recently, our group found that melatonin receptor 1B (MT2) gene polymorphism was associated with the occurrence of AIS. Hence, the present study investigated the effect of melatonin on AIS osteoblasts. In vitro assays were performed with osteoblasts isolated from 17 severe AIS girls and nine control subjects. The osteoblasts were exposed to different concentrations of melatonin for 3 days. The effects of melatonin on cell proliferation (as evidenced by MTT assay) and differentiation (demonstrated by alkaline phosphatase activity) were determined. In the control group, melatonin significantly stimulated osteoblasts to proliferate and differentiate. However, in the AIS group, the stimulatory effects of melatonin were not discernible. Importantly, this finding demonstrated that there is a significant difference between AIS and control osteoblasts in functional response toward melatonin. Melatonin-stimulated proliferation of control osteoblasts was inhibited by the MT2 antagonist, 4-phenyl-2-propionamidotetraline, as well as by luzindole, a nonselective melatonin receptor antagonist, suggesting that MT2 is associated with the proliferative action of melatonin. The lack of response in AIS osteoblasts might be because of dysfunction of the melatonin signaling pathway, which may contribute to the low bone mineral density and abnormal skeletal growth observed in patients with AIS.