When β-cells fail: lessons from dedifferentiation

Diabetes is caused by a combination of impaired responsiveness to insulin and reduced production of insulin by the pancreas. Until recently, the decline of insulin production had been ascribed to β-cell death. But recent research has shown that β-cells do not die in diabetes, but undergo a silencing process, termed "dedifferentiation." The main implication of this discovery is that β-cells can be revived by appropriate treatments. We have shown that mitochondrial abnormalities are a key step in the progression of β-cell dysfunction towards dedifferentiation. In normal β-cells, mitochondria generate energy required to sustain insulin production and its finely timed release in response to the body's nutritional status. A normal β-cell can adapt its mitochondrial fuel source based on substrate availability, a concept known as "metabolic flexibility." This capability is the first casualty in the progress of β-cell failure. β-Cells lose the ability to select the right fuel for mitochondrial energy production. Mitochondria become overloaded, and accumulate by-products derived from incomplete fuel utilization. Energy production stalls, and insulin production drops, setting the stage for dedifferentiation. The ultimate goal of these investigations is to explore novel treatment paradigms that will benefit people with diabetes.

The effects of posterior cruciate ligament deficiency on posterolateral corner structures under gait- and squat-loading conditions: A computational knee model

Objectives

The aim of the current study was to analyse the effects of posterior cruciate ligament (PCL) deficiency on forces of the posterolateral corner structure and on tibiofemoral (TF) and patellofemoral (PF) contact force under dynamic-loading conditions.

Methods

A subject-specific knee model was validated using a passive flexion experiment, electromyography data, muscle activation, and previous experimental studies. The simulation was performed on the musculoskeletal models with and without PCL deficiency using a novel force-dependent kinematics method under gait- and squat-loading conditions, followed by probabilistic analysis for material uncertain to be considered.

Results

Comparison of predicted passive flexion, posterior drawer kinematics and muscle activation with experimental measurements showed good agreement. Forces of the posterolateral corner structure, and TF and PF contact forces increased with PCL deficiency under gait- and squat-loading conditions. The rate of increase in PF contact force was the greatest during the squat-loading condition. The TF contact forces increased on both medial and lateral compartments during gait-loading conditions. However, during the squat-loading condition, the medial TF contact force tended to increase, while the lateral TF contact forces decreased. The posterolateral corner structure, which showed the greatest increase in force with deficiency of PCL under both gait- and squat-loading conditions, was the popliteus tendon (PT).

Conclusion

PCL deficiency is a factor affecting the variability of force on the PT in dynamic-loading conditions, and it could lead to degeneration of the PF joint.

Cite this article: K-T. Kang, Y-G. Koh, M. Jung, J-H. Nam, J. Son, Y.H. Lee, S-J. Kim, S-H. Kim. The effects of posterior cruciate ligament deficiency on posterolateral corner structures under gait- and squat-loading conditions: A computational knee model. Bone Joint Res 2017;6:31–42. DOI: 10.1302/2046-3758.61.BJR-2016-0184.R1.

Effects of tallow and escape protein on lactational and reproductive performance of dairy cows

Experiments were performed to determine the effect of energy source and proportion of escape protein on lactational performance, body measurements, and reproductive activity. Sixty-eight lactating Holstein cows were assigned to one of four dietary treatments during wk 2 to 12 postpartum: 1) high fat (3% tallow), high escape protein (5% feather meal:blood meal, 85:15, DM basis); 2) high fat, low escape protein (0% feather meal:blood meal); 3) low fat (0% tallow), high escape protein; and 4) low fat, low escape protein. Diets were similar in energy and CP contents. Overall mean milk yield (32.9 kg/d) was not affected by diet, but efficiency of FCM yield was highest with high fat and high escape protein. Daily DMI and net energy balance were greater for cows fed the diet low in fat and low in escape protein, but days to first ovulation were not different among groups. Total cholesterol in plasma increased as DIM increased, and concentrations were greater for cows fed the high fat diets than for cows fed the low fat diets after 35 DIM. Concentrations of luteal phase progesterone and follicular phase estradiol tended to be greater for cows fed the high fat and low escape protein, but conception rate from first AI was greatest for cows fed the high fat and high escape protein. Supplemental tallow and escape protein did not consistently affect lactational performance but did improve efficiency of FCM yield and conception rate from first AI.

Measuring the effect of femoral malrotation on knee joint biomechanics for total knee arthroplasty using computational simulation

Objectives

Malrotation of the femoral component can result in post-operative complications in total knee arthroplasty (TKA), including patellar maltracking. Therefore, we used computational simulation to investigate the influence of femoral malrotation on contact stresses on the polyethylene (PE) insert and on the patellar button as well as on the forces on the collateral ligaments.

Materials and Methods

Validated finite element (FE) models, for internal and external malrotations from 0° to 10° with regard to the neutral position, were developed to evaluate the effect of malrotation on the femoral component in TKA. Femoral malrotation in TKA on the knee joint was simulated in walking stance-phase gait and squat loading conditions.

Results

Contact stress on the medial side of the PE insert increased with internal femoral malrotation and decreased with external femoral malrotation in both stance-phase gait and squat loading conditions. There was an opposite trend in the lateral side of the PE insert case. Contact stress on the patellar button increased with internal femoral malrotation and decreased with external femoral malrotation in both stance-phase gait and squat loading conditions. In particular, contact stress on the patellar button increased by 98% with internal malrotation of 10° in the squat loading condition. The force on the medial collateral ligament (MCL) and the lateral collateral ligament (LCL) increased with internal and external femoral malrotations, respectively.

Conclusions

These findings provide support for orthopaedic surgeons to determine a more accurate femoral component alignment in order to reduce post-operative PE problems.

Cite this article: K-T. Kang, Y-G. Koh, J. Son, O-R. Kwon, C. Baek, S. H. Jung, K. K. Park. Measuring the effect of femoral malrotation on knee joint biomechanics for total knee arthroplasty using computational simulation. Bone Joint Res 2016;5:552–559. DOI: 10.1302/2046-3758.511.BJR-2016-0107.R1.

Preservation of kinematics with posterior cruciate-, bicruciate- and patient-specific bicruciate-retaining prostheses in total knee arthroplasty by using computational simulation with normal knee model

Objectives

Preservation of both anterior and posterior cruciate ligaments in total knee arthroplasty (TKA) can lead to near-normal post-operative joint mechanics and improved knee function. We hypothesised that a patient-specific bicruciate-retaining prosthesis preserves near-normal kinematics better than standard off-the-shelf posterior cruciate-retaining and bicruciate-retaining prostheses in TKA.

Methods

We developed the validated models to evaluate the post-operative kinematics in patient-specific bicruciate-retaining, standard off-the-shelf bicruciate-retaining and posterior cruciate-retaining TKA under gait and deep knee bend loading conditions using numerical simulation.

Results

Tibial posterior translation and internal rotation in patient-specific bicruciate-retaining prostheses preserved near-normal kinematics better than other standard off-the-shelf prostheses under gait loading conditions. Differences from normal kinematics were minimised for femoral rollback and internal-external rotation in patient-specific bicruciate-retaining, followed by standard off-the-shelf bicruciate-retaining and posterior cruciate-retaining TKA under deep knee bend loading conditions. Moreover, the standard off-the-shelf posterior cruciate-retaining TKA in this study showed the most abnormal performance in kinematics under gait and deep knee bend loading conditions, whereas patient-specific bicruciate-retaining TKA led to near-normal kinematics.

Conclusion

This study showed that restoration of the normal geometry of the knee joint in patient-specific bicruciate-retaining TKA and preservation of the anterior cruciate ligament can lead to improvement in kinematics compared with the standard off-the-shelf posterior cruciate-retaining and bicruciate-retaining TKA.

Cite this article: Y-G. Koh, J. Son, S-K. Kwon, H-J. Kim, O-R. Kwon, K-T. Kang. Preservation of kinematics with posterior cruciate-, bicruciate- and patient-specific bicruciate-retaining prostheses in total knee arthroplasty by using computational simulation with normal knee model. Bone Joint Res 2017;6:557–565. DOI: 10.1302/2046-3758.69.BJR-2016-0250.R1.

Enhancement of paclitaxel production by temperature shift in suspension culture of Taxus chinensis

Effect of temperature shift during culture period on cell growth and paclitaxel was investigated to optimize paclitaxel production in suspension culture of Taxus chinensis. Cell growth showed the optimum at 24 degrees C while paclitaxel synthesis showed the maximum at 29 degrees C. To minimize the inhibitory effect of higher temperature on cell growth, temperature was shifted after a certain period of culture time at 24 degrees C. Paclitaxel synthesis in plant cell culture increased dramatically during day 14 to day 21 regardless of treatment, reaching the maximum production of 137.5 mg paclitaxel/L. When the temperature was maintained at 29 degrees C after day 21, the specific productivity of paclitaxel was sustained for prolonged period of 42 days. The possible relationship between temperature and paclitaxel synthetic pathway was also suggested.

Computational study on the effect of malalignment of the tibial component on the biomechanics of total knee arthroplasty: A Finite Element Analysis

Objectives

Malalignment of the tibial component could influence the long-term survival of a total knee arthroplasty (TKA). The object of this study was to investigate the biomechanical effect of varus and valgus malalignment on the tibial component under stance-phase gait cycle loading conditions.

Methods

Validated finite element models for varus and valgus malalignment by 3° and 5° were developed to evaluate the effect of malalignment on the tibial component in TKA. Maximum contact stress and contact area on a polyethylene insert, maximum contact stress on patellar button and the collateral ligament force were investigated.

Results

There was greater total contact stress in the varus alignment than in the valgus, with more marked difference on the medial side. An increase in ligament force was clearly demonstrated, especially in the valgus alignment and force exerted on the medial collateral ligament also increased.

Conclusion

These results highlight the importance of accurate surgical reconstruction of the coronal tibial alignment of the knee joint. Varus and valgus alignments will influence wear and ligament stability, respectively in TKA.

Cite this article: D-S. Suh, K-T. Kang, J. Son, O-R. Kwon, C. Baek, Y-G. Koh. Computational study on the effect of malalignment of the tibial component on the biomechanics of total knee arthroplasty: A Finite Element Analysis. Bone Joint Res 2017;6:623–630. DOI: 10.1302/2046-3758.611.BJR-2016-0088.R2.

Chromatin in the nuclear landscape

Chromatin affects many, if not all aspects, of nuclear organization and function. For this reason, we have focused our attention on elucidating some of the basic mechanisms regulating the formation and maintenance of chromatin, specifically concerning Polycomb repressive complex 2 (PRC2) and PR-Set7. PRC2 is responsible for catalyzing trimethylation of lysine 27 of histone H3 and thus has a critical role in the formation of facultative heterochromatin. PR-Set7 is responsible for catalyzing monomethylation of lysine 20 of histone H4 and is required for proper cell cycle progression and DNA damage response. We have also expanded our work to establish novel techniques and approaches to determine how chromatin is spatially regulated within the nuclear landscape.

A computational simulation study to determine the biomechanical influence of posterior condylar offset and tibial slope in cruciate retaining total knee arthroplasty

Objectives

Posterior condylar offset (PCO) and posterior tibial slope (PTS) are critical factors in total knee arthroplasty (TKA). A computational simulation was performed to evaluate the biomechanical effect of PCO and PTS on cruciate retaining TKA.

Methods

We generated a subject-specific computational model followed by the development of ± 1 mm, ± 2 mm and ± 3 mm PCO models in the posterior direction, and -3°, 0°, 3° and 6° PTS models with each of the PCO models. Using a validated finite element (FE) model, we investigated the influence of the changes in PCO and PTS on the contact stress in the patellar button and the forces on the posterior cruciate ligament (PCL), patellar tendon and quadriceps muscles under the deep knee-bend loading conditions.

Results

Contact stress on the patellar button increased and decreased as PCO translated to the anterior and posterior directions, respectively. In addition, contact stress on the patellar button decreased as PTS increased. These trends were consistent in the FE models with altered PCO. Higher quadriceps muscle and patellar tendon force are required as PCO translated in the anterior direction with an equivalent flexion angle. However, as PTS increased, quadriceps muscle and patellar tendon force reduced in each PCO condition. The forces exerted on the PCL increased as PCO translated to the posterior direction and decreased as PTS increased.

Conclusion

The change in PCO alternatively provided positive and negative biomechanical effects, but it led to a reduction in a negative biomechanical effect as PTS increased.

Cite this article: K-T. Kang, Y-G. Koh, J. Son, O-R. Kwon, J-S. Lee, S. K. Kwon. A computational simulation study to determine the biomechanical influence of posterior condylar offset and tibial slope in cruciate retaining total knee arthroplasty. Bone Joint Res 2018;7:69–78. DOI: 10.1302/2046-3758.71.BJR-2017-0143.R1.

Long-term outcomes of laparoscopic large hiatus hernia repair with nonabsorbable mesh

The use of mesh to augment suture repair of large hiatus hernias remains controversial. Repair with mesh may help reduce the recurrence rate of primary repair, but concerns about the potential for serious complications, such as mesh erosion or stricturing, continue to limit its use. We aim to evaluate the long-term outcome of primary hiatus hernia repair with lightweight polypropylene mesh (TiMesh) specifically looking at rates of clinical recurrence, dysphagia, and mesh-related complications. From a prospectively maintained database, 50 consecutive patients who underwent elective primary laparoscopic hiatal hernia repair with TiMesh between January 2005 and December 2007 were identified. Case notes and postoperative endoscopy reports were reviewed. Clinical outcomes were evaluated using a structured questionnaire, including a validated dysphagia score. Of the 50 patients identified, 36 (72%) were contactable for follow-up. At a median follow-up of 9 years, the majority of patients (97%) regarded their surgery as successful. Twelve patients (33%) reported a recurrence of their symptoms, but only 4 (11%) reported that their symptoms were as severe as prior to the surgery. There was no significant difference between pre- and postoperative dysphagia scores. Postoperative endoscopy reports were available for 32 patients at a median time point of 4 years postoperatively, none of which revealed any mesh-related complications. One patient had undergone a revision procedure for a recurrent hernia at another institution. In this series, primary repair of large hiatus hernia with nonabsorbable mesh was not associated with any adverse effects over time. Patient satisfaction with symptomatic outcome remained high in the long term.

Noise characterization of a self-mode-locked Ti:sapphire laser

The phase and amplitude noise spectra of a self-mode-locked Ti:sapphire laser are measured and compared with the noise characteristics of a colliding-pulse mode-locked (CPM) dye laser. The timing jitter of the Ti:sapphire laser is found to be approximately half that of the CPM laser for jitter rates above 50 Hz. The amplitude noise of both lasers is comparable for frequencies of as much as several hundred kilohertz. However, between 0.5 and 5 MHz the noise spectrum of the Ti:sapphire laser is 126-134 dB below the carrier, while the CPM laser noise is limited by the pump laser at 115-131 dB below the carrier.

A New Approach to Quantify and Grade Radiation Dermatitis Using Deep-Learning Segmentation in Skin Photographs

AIMS

Objective evaluation of radiation dermatitis is important for analysing the correlation between the severity of radiation dermatitis and dose distribution in clinical practice and for reliable reporting in clinical trials. We developed a novel radiation dermatitis segmentation system based on convolutional neural networks (CNNs) to consistently evaluate radiation dermatitis.

MATERIALS AND METHODS

The radiation dermatitis segmentation system is designed to segment the radiation dermatitis occurrence area using skin photographs and skin-dose distribution. A CNN architecture with a dilated convolution layer and skip connection was designed to estimate the radiation dermatitis area. Seventy-three skin photographs obtained from patients undergoing radiotherapy were collected for training and testing. The ground truth of radiation dermatitis segmentation is manually delineated from the skin photograph by an experienced radiation oncologist and medical physicist. We converted the skin photographs to RGB (red-green-blue) and CIELAB (lightness (L^∗), red-green (a^∗) and blue-yellow (b^∗)) colour information and trained the network to segment faint and severe radiation dermatitis using three different input combinations: RGB, RGB + CIELAB (RGBLAB) and RGB + CIELAB + skin-dose distribution (RGBLAB_D). The proposed system was evaluated using the Dice similarity coefficient (DSC), sensitivity, specificity and normalised Matthews correlation coefficient (nMCC). A paired t-test was used to compare the results of different segmentation performances.

RESULTS

Optimal data composition was observed in the network trained for radiation dermatitis segmentation using skin photographs and skin-dose distribution. The average DSC, sensitivity, specificity and nMCC values of RGBLAB_D were 0.62, 0.61, 0.91 and 0.77, respectively, in faint radiation dermatitis, and 0.69, 0.78, 0.96 and 0.83, respectively, in severe radiation dermatitis.

CONCLUSION

Our study showed that CNN-based radiation dermatitis segmentation in skin photographs of patients undergoing radiotherapy can describe radiation dermatitis severity and pattern. Our study could aid in objectifying the radiation dermatitis grading and analysing the reliable correlation between dosimetric factors and the morphology of radiation dermatitis.

Spin-Orbit Coupling and Interband Transitions in the Optical Conductivity of Sr_{2}RhO_{4}

The prototypical correlated metal Sr_{2}RhO_{4} was studied using optical and photoemission spectroscopy. At low energies and temperatures, the optical data reveal a complex, multicomponent response that on the surface points to an unconventional metallic state in this material. Via a comparison with photoemission, the anomalous optical response may be attributed to an unexpectedly strong interband transition near 180 meV between spin-orbit coupled bands that are nearly parallel along ΓX. This spin-orbit coupling effect is shown to occur in a number of related metallic ruthenates and explains the previously puzzling optical properties reported for these materials.

CRISPR/Cas9 genome editing system confirms centriolin's role in cytokinesis

Objective

In addition to its function as the microtubule organizing center of the cell, the centrosome has functions in many other cellular processes including primary cilia formation, DNA damage checkpoints, and cell cycle progression. But the role of individual components of the centrosome in these processes remains unclear. Previous studies used siRNA (small interfering RNA) to “knock down” protein levels of the centrosome component centriolin, resulting in failed cytokinesis. Since this approach was transient, only targeting centriolin at the mRNA level, we sought to confirm these findings by permanently disrupting the gene encoding centriolin using the CRISPR/Cas9 system of genome editing.

Results

This study provides evidence that the CRISPR/Cas9 system is capable of effectively reducing centriolin protein levels in the cell. Furthermore, this disruption leads to a failure of cytokinesis that is reminiscent of the phenotype previously reported for the siRNA-mediated disruption of centriolin. Furthermore, no additional defects in cell division were observed, consistent with results seen with previous siRNA studies. We conclude that the CRISPR/Cas9 system is an effective means of permanently removing the cellular pools of centriolin and that the disruption of centriolin at both the mRNA level and genomic level lead to similar cell division defects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05898-w.

Suppression of near-Fermi level electronic states at the interface in a LaNiO3/SrTiO3 superlattice

Standing-wave-excited photoemission is used to study a SrTiO3/LaNiO3 superlattice. Rocking curves of core-level and valence band spectra are used to derive layer-resolved spectral functions, revealing a suppression of electronic states near the Fermi level in the multilayer as compared to bulk LaNiO3. Further analysis shows that the suppression of these states is not homogeneously distributed over the LaNiO3 layers but is more pronounced near the interfaces. Possible origins of this effect and its relationship to a previously observed metal-insulator-transition in ultrathin LaNiO3 films are discussed.

The relationship of various measures of time urgency to indices of physical health

The degree of association with two general health indices was assessed for three separate measures of time urgency. The Speed and Impatience subscale of the Jenkins Activity Survey was found to have no significant relationships with the health indices. The Time Urgency/Perpetual Activation (TUPA) scale, as well as the Irritability and Impatience scale, did correlate in comparable ways with a majority of the health indicators. A very brief, 2-item impatience subscale of the Irritability and Impatience Scale also correlated with health indices in essentially the same manner as the complete Irritability and Impatience Scale and the TUPA Scale. It was concluded that because of its convenience of administration, the very brief 2-item impatience subscale of the Irritability and Impatience Scale may constitute the instrument of choice for assessing time urgency as it relates to noncardiovascular health. A question is raised regarding whether anger and time urgency constitute separate factors or are aspects of a single behavioral trait.

Absorption, distribution, metabolism and excretion of telmesteine, a mucolitic agent, in rat

1. The metabolism and disposition of telmesteine, a muco-active agent, have been investigated following single oral or intravenous administration of (14)C-telmesteine in the Sprague-Dawley rat. 2. (14)C-telmesteine was rapidly absorbed after oral dosing (20 and 50 mg kg(-1)) with an oral bioavailability of >90% both in male and female rats. The C(max) and area under the curve of the radioactivity in plasma increased proportionally to the administered dose and those values in female rats were 30% higher than in male rats. 3. Telmesteine was distributed over all organs except for brain and the tissue/plasma ratio of the radioactivity 30 min after dosing was relatively low with a range of 0.1-0.8 except for excretory organs. 4. Excretion of the radioactivity was 86% of the dose in the urine and 0.6% in the faeces up to 7 days after oral administration. Biliary excretion of the radioactivity in bile duct-cannulated rats was about 3% for the first 24 h. The unchanged compound mainly accounted for the radioactivity in the urine and plasma. 5. Telmesteine was hardly metabolized in microsomal incubations. A glucuronide conjugate was detected in the urine and bile, but the amount of glucuronide was less than 6% of excreted radioactivity.

Responses from new receptive fields of VPL neurones following deafferentation

Single unit recordings were made from the ventral posterior lateral thalamus of anaesthetized rats to characterize responses to the activation of new receptive fields induced by either local anaesthesia or amputation. Receptive fields confined to single digits were identified and evoked unit responses to the stimulation of single digits were quantitated before and after deafferentation. Although both methods of denervation rapidly induced similar new receptive fields from the adjacent single digit, they exhibited quite different temporal changes of the evoked unit responses from new receptive fields. This difference in the evoked unit responses from the new receptive fields may be related to either the different nature or the outcome of the two types of deafferentation.

Development of Novel Focal Irradiation Tool for High-Precision Irradiation Using Clinical Brachytherapy System

PURPOSE/OBJECTIVE(S)

Several small animals, including mice, are used to conduct research on state-of-the-art radiation therapy techniques or treatment-related toxicity. However, it is difficult to conduct the focal irradiation to a shallow depth on small animals, because irradiation using LINAC has limitations in energy and field size. The purpose of this paper was to develop a focal irradiation tool for high-precision irradiation and to evaluate beam characteristics.

MATERIALS/METHODS

We designed the collimator of 1 mm diameter consisting of tungsten material for high-precision irradiation applied to the clinical brachytherapy system and the percent depth dose and horizontal profile were measured. We compared the depth dose and horizontal profile with 4 mm diameter SRS cone for 6 MV in LINAC. We measured the PDD and horizontal profile using EBT3 film for high-precision irradiation of 1 mm diameter using Ir-192 source. In case of 4 mm diameter, the beam was measured using edge detector. In addition, all measurements were compared with the results of planning tool simulation.

RESULTS

In case of focal irradiation tool, the maximum dose showed at the surface for both measurement and simulation, and 26% and 32% doses at 1 mm depth, respectively. In addition, FWHM at a 1 mm depth showed that high-precision irradiation was possible with measurement and simulation results of 1.86 and 1.28 mm. In case of LINAC, the maximum dose was showed at a depth of 1 cm and 0.8 cm in the measurement and simulation, respectively. Even if the smallest cone is used, the FWHM at a dmax depth was 4.0 mm in both simulation and measurement.

CONCLUSION

We overcame the limitation for energy and field size through the focal irradiation tool for high-precision irradiation. The focal irradiation tool enables high dose delivery to the shallow depth. In addition, small FWHM reduced dose delivery to the periphery at a specific depth and enabled accurate dose delivery. These results mean that the focal irradiation tool can be useful in small animal experiments that require accurate doses near the shallow depth.