Muscle strength, motor performance, cardiac and muscle biomarkers in detection of muscle side effects during and after acute lymphoblastic leukemia treatment in children

Identifying causes of balance impairment and exploring sensory contributions to balance in pediatric oncology: A scoping review

PURPOSE

To identify causes of balance impairment in children undergoing treatment for cancer and childhood cancer survivors.

METHODS

A systematic search was performed according to PRISMA guidelines. Studies were included if participants were 0-19 years of age with a current/past diagnosis of cancer, an objective balance measure was reported, and a cause of balance impairment was either stated or implied.

RESULTS

The 64 full text studies included identified balance impairments as sequelae secondary to CNS tumors, and/or as an effect of medical treatment including chemotherapy, radiation, and/or surgery. Cancer treatment can result in damage to the visual, vestibular and/or somatosensory systems which in turn can contribute to balance dysfunction.

CONCLUSIONS

Balance impairments were caused by the cancer itself or the result of medical treatment. Oncology professionals are integral in recognition and treatment of factors affecting balance impairments in childhood cancer; however, further research is needed to identify interventions targeting specific causes of balance impairment.

Physical impairments, activity limitations, and participation restrictions of childhood acute lymphoblastic leukemia survivors with and without hip osteonecrosis: a PETALE cohort study

PURPOSE

Long-term musculoskeletal complications represent a growing burden for survivors of childhood acute lymphoblastic leukemia (cALL). This study aimed to describe physical impairments, activity limitations, and participation restrictions in a high-risk subgroup of cALL survivors of the PETALE cohort.

METHODS

This cross-sectional study, using observational data from the PETALE cohort, included a subgroup of survivors who presented high-risk criteria for late effects. Outcomes measures consisted of hip magnetic resonance imaging, maximal isometric muscle strength (MIMS) or torque (MIMT), range of motion (ROM), Near Tandem Balance (NTB), 6-Minute Walk Test (6MWT), Five Time Sit-to-Stand Test (FTSST), and health-related quality of life. Descriptive statistics and regression analyses were performed.

RESULTS

Survivors (n = 97, 24.2 ± 6.7 years old) showed limited grip strength, FTSST, and NTB performance compared to reference values (p < 0.001). Thirteen participants (14.6%, 18 hips) had hip osteonecrosis (ON) (53.8% male). Higher severity hip ON was found in female survivors (66.7% vs. 22.2%). Survivors with hip ON had reduced hip external rotation ROM compared to those without (p < 0.05). Relationships were found between MIMS and ROM outcomes (r = 0.32, p < 0.01) and with 6MWT (r = 0.39-0.41, p < 0.001). Our multiple linear regression model explained 27.6% of the variance of the 6MWT.

CONCLUSIONS

Survivors in our subgroup had clinically significant physical impairments and activity limitations, and those with hip ON showed worst hip impairment outcomes.

IMPLICATIONS FOR CANCER SURVIVORS

These findings emphasize the importance of long-term follow-up including physical therapy assessment to help early identification and management of physical impairments and activity limitations in survivors of cALL.

Physical Activity Levels and Factors Affecting Them in Hospitalized Children With Leukemia

BACKGROUND

Physical activity promotes healthy physical and mental development in children with leukemia. However, the level of physical activity in hospitalized children with leukemia and the factors that influence it are unknown.

OBJECTIVES

The aims of this study were to understand the physical activity level of hospitalized children with leukemia and to explore the factors influencing it to provide a reference for physical activity assessment and intervention in such children.

METHODS

A total of 133 hospitalized children with leukemia completed a general information questionnaire, the Chinese University of Hong Kong Physical Activity Rating for Children and Youth, and the Children's Social Anxiety Scale. A cross-sectional study was used to explore the effects of different variables on the children's activity levels.

RESULTS

Among the study participants, 44.4% had a low-intensity activity level, 35.3% had a moderate-intensity activity level, and 20.3% had a high-intensity activity level, with a total physical activity rating of 3 (1, 6). Chemotherapy phase (P = .007), screen time (P = .001), and social anxiety (P = .012) were identified as influential factors.

CONCLUSIONS

Our results showed that children with hospitalized leukemia had lower-intensity physical activity levels, especially in the chemotherapy phase of induction remission. Furthermore, screen time and social anxiety had negative effects on the children's activity levels.

IMPLICATIONS FOR PRACTICE

According to the physical activity level of the children and the influencing factors, healthcare professionals should gradually improve children's mobility and promote their physical and mental health development through guidance and encouragement, and the development of personalized activity intervention programs.

Physical capacity in children and adolescents with newly diagnosed cancer: A systematic review and meta-analysis

OBJECTIVE

To review the body of evidence on cardiorespiratory fitness, muscle strength, and physical performance in children with newly diagnosed cancer, five databases (MEDLINE, Embase, CINAHL, CENTRAL, and Web of Science) were searched on December 19, 2022.

METHODS

Thirteen studies, embodying 594 participants within 1 month of cancer diagnosis and 3674 healthy controls were included. Eighteen different outcomes on cardiorespiratory fitness (n = 2), muscle strength (n = 5), physical performance (n = 10), and adverse events (n = 1) were analyzed.

RESULTS

Fifteen out of 17 outcomes on physical capacity showed severe impairments compared with healthy controls. Where possible, random-effects meta-analysis was conducted to synthesize the results. No adverse events were reported related to testing.

CONCLUSION

Children with cancer have impaired cardiorespiratory fitness, muscle strength, and physical performance within the first month after diagnosis. However, the evidence is based on a small number of studies with large clinical heterogeneity, limiting the certainty of evidence.

Supervised Exercise Interventions in Childhood Cancer Survivors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Childhood cancer survivors (CCSs) may suffer from a multitude of health impairments, resulting in a compromised quality of life (QoL). This review’s objective was to examine CCSs’ adherence to supervised exercise training interventions and the impact of these interventions on health outcomes. Methods: The following databases were searched in May 2022: PubMed, Embase, Cochrane Library, and Web of Science. The included studies were limited to randomized controlled trials (RCTs), published in English involving CCSs aged 18 years and below. Results: Nine RCTs (n = 642 participants) were included in the systematic review, and seven of them (n = 551 participants) were included in the meta-analysis. Both the mean retention rate and adherence to the supervised exercise interventions were 87%. Supervised exercise interventions significantly improved muscle strength (standardized mean difference (SMD) = 1.42, p = 0.03), level of daily physical activity (SMD = 1.05, p < 0.001), body mass index (BMI) (mean difference (MD) = 1.06, p = 0.03), and fatigue (SMD = −0.44, p < 0.001), while there was no statistical significance in the quality of life (QoL) (SMD = 0.21, p = 0.20). Conclusions: The adherence of CCSs to supervised exercise interventions is high, and supervised exercise interventions are safe and effective.

Gut Microbiome Suffers from Hematopoietic Stem Cell Transplantation in Childhood and Its Characteristics Are Positively Associated with Intra-Hospital Physical Exercise

Gut microbiome impairment is a serious side effect of cancer treatment. The aim of this study was to identify the effects of hematopoietic stem cell transplantation (HSCT) treatment on gut microbiota composition in children with acute lymphoblastic leukemia (ALL). Fecal microbiotas were categorized using specific primers targeting the V1-V3 region of 16S rDNA in eligible pediatric ALL patients after HSCT (n = 16) and in healthy controls (Ctrl, n = 13). An intra-hospital exercise program was also organized for child patients during HSCT treatment. Significant differences in gut microbiota composition were observed between ALL HSCT and Ctrl with further negative effects. Plasma C-reactive protein correlated positively with the pathogenic bacteria Enterococcus spp. and negatively with beneficial bacteria Butyriccocus spp. or Akkermansia spp., respectively (rs = 0.511, p = 0.05; rs = -0.541, p = 0.04; rs = -0.738, p = 0.02). Bacterial alpha diversity correlated with the exercise training characteristics. Therefore, specific changes in the microbiota of children were associated with systemic inflammation or the ability to exercise physically during HSCT treatment.

Physical and functional performance assessment in pediatric oncology: a systematic review

BACKGROUND

Research indicates reduced physical performance from diagnosis into survivorship of pediatric cancer patients. However, there is no systematic information or guideline available on the methods to assess physical performance and function in this population. The purpose was to systematically compile and describe assessments of physical performance and function in patients and survivors of pediatric cancer, including cardiorespiratory fitness, muscle strength, speed, balance, flexibility, functional mobility, gait and motor performance test batteries.

METHODS

We searched the databases PubMed, SPORTDiscus, and Cochrane Database and performed abstract and full-text selection of 2619 articles according to the Cochrane Handbook of Systematic Reviews. Information on patients characteristics, assessments, information on validity and reliability, and relevant references was extracted.

RESULTS

In summary, 63 different assessments were found in 149 studies including 11639 participants. Most studies evaluated cardiorespiratory fitness and muscle strength with the majority conducted off treatment. Some outcomes (e.g. speed) and diagnoses (e.g. neuroblastoma) were severely underrepresented. With the exception of gait, leukemia patients represented the largest group of individuals tested.

CONCLUSIONS

Insufficient data and patient heterogeneity complicate uniform recommendations for assessments. Our results support researchers and practitioners in selecting appropriate assessment to meet their specific research questions or individual daily practice needs.

IMPACT

This systematic review includes 149 studies and provides a comprehensive summary of 63 assessments to evaluate cardiorespiratory fitness, muscle strength, speed, balance, flexibility, functional mobility, gait or motor performance test batteries in patients and survivors of pediatric cancer. We present the most studied fields within the pediatric cancer population, which are cardiorespiratory fitness and muscle strength, off treatment phase, and leukemia patients. We propose research priorities by identification of subgroups in terms of cancer type, phase of treatment, and outcome of interest that are underrepresented in studies currently available.

The Impact of a Precision-Based Exercise Intervention in Childhood Hematological Malignancies Evaluated by an Adapted Yo-Yo Intermittent Recovery Test

During cancer treatments in childhood hematological malignancies, reduced exercise tolerance is one of the main hardships. Precision-based training programs help children, adolescents, and young adults and their families to resume regular physical activity, exercise, and sports once they return to their communities after the intensive phases spent in hospital. This study was aimed at verifying whether an intermittent recovery test, the Yo-Yo AD, could provide a simple and valid way to evaluate an individual’s capacity to perform repeated intense exercise and to follow up on the impact of tailored exercise in children, adolescents, and young adults with hematological malignancies. The Yo-Yo AD involved the repetition of several shuttles to muscle exhaustion, at pre-established speeds (walking and slow running). The heart rate (HR) and oxygen saturation (SaO2) were monitored during the test. The total distance and the walking/running ability, measured as the slope of the HR vs. distance correlation, were investigated before (T0) and after 11 weeks (T1) of precision exercise intervention. The Yo-Yo AD was also performed by healthy children (CTRL). Ninety-seven patients (10.58 ± 4.5 years, 46% female) were enrolled. The Yo-Yo AD showed the positive impact of the exercise intervention by increasing the distance covered by the individuals (T0 = 946.6 ± 438.2 vs. T1 = 1352.3 ± 600.6 m, p < 0.001) with a more efficient walking/running ability (T0 = 2.17 ± 0.84 vs. T1 = 1.73 ± 0.89 slope, p < 0.0164). CTRLs performed better (1754.0 ± 444.0 m, p = 0.010). They were equally skillful (1.71 ± 0.27 slope) when compared to the patients after they received the precision-based intervention. No adverse events occurred during the Yo-Yo AD and it proved to be an accurate way of correctly depicting the changes in performance in childhood hematological malignancies.

Osteopathic Treatment and Evaluation in the Clinical Setting of Childhood Hematological Malignancies

Simple Summary

Children: adolescents, and young adults who are affected by hematological malignancies and who are undergoing intensive phases of cancer treatment including hematopoietic stem cell transplantation, experience diminished functional ability. This study was aimed at assessing if osteopathic treatment and evaluation can be used when an 11-week precision-based exercise program is run inside the hospital. Our results support that osteopathy plus precision-based intervention could be a desirable support in the clinical prise en charge of these children and adolescents. Osteopathy is a safe method for the evaluation of clinical conditions and requires strong multidisciplinary synergy between pediatricians and exercise physiologists.

Abstract

Children: adolescents, and young who are adults affected with hematological malignancies (CAYA-H) and who are undergoing intensive phases of cancer treatment, including hematopoietic stem cell transplantation (HSCT), experience diminished functional ability. This study was aimed at assessing the feasibility, efficacy, safety, and satisfaction of an osteopathic intervention in CAYA-H attending an 11-week precision-based exercise program (PEx). All of the participants were given 4–10 treatments according to the prescription ordered by the sports medicine doctor in charge of the PEx, and the following outcomes were assessed: (1) spinal column range of motion (ROM) by palpation; (2) lower and upper limb joints ROM by a goniometer; (3) orthostatic posture by plumb line assessment; (4) chest and abdomen mobility by inspection and palpation; (5) cranial-sacral rhythmic impulse (CRI) by palpation; and (6) adverse effects. Goal attainment scaling (GAS) was used to identify the accomplishment of a desired clinical result. Moreover, HSCT patients who were affected with graft-versus-host disease and/or osteonecrosis had their joints assessed in terms of ROM as tools to monitor the effectiveness of immunosuppressive treatment. A total of 231 CAYA-H were identified, and 104 participated in the study (age 10.66 ± 4.51 yrs; 43% F). PEx plus osteopathy reached positive GAS scores by improving the ROMs of the spinal column and/or limbs (81% and 78%, respectively), chest and abdomen mobility (82%), and CRI (76%). Only minor reversible adverse effects were noticed during the study. Together, our data seem to initiate a new course where osteopathy could be useful in evaluating structural edges due to the clinical history of each CAYA-H. Given the contributions that were obtained by the GAS scores, osteopathic treatment seems to reveal interesting potential that can be targeted in the future.

Skeletal Muscle and Childhood Cancer: Where are we now and where we go from here

Skeletal muscle (muscle) is essential for physical health and for metabolic integrity, with sarcopenia (progressive muscle mass loss and weakness), a pre-curser of aging and chronic disease. Loss of lean mass and muscle quality (force generation per unit of muscle) in the general population are associated with fatigue, weakness, and slowed walking speed, eventually interfering with the ability to maintain physical independence, and impacting participation in social roles and quality of life. Muscle mass and strength impairments are also documented during childhood cancer treatment, which often persist into adult survivorship, and contribute to an aging phenotype in this vulnerable population. Although several treatment exposures appear to confer increased risk for loss of mass and strength that persists after therapy, the pathophysiology responsible for poor muscle quantity and quality is not well understood in the childhood cancer survivor population. This is partly due to limited access to both pediatric and adult survivor muscle tissue samples, and to difficulties surrounding non-invasive investigative approaches for muscle assessment. Because muscle accounts for just under half of the body's mass, and is essential for movement, metabolism and metabolic health, understanding mechanisms of injury responsible for both initial and persistent dysfunction is important, and will provide a foundation for intervention. The purpose of this review is to provide an overview of the available evidence describing associations between childhood cancer, its treatment, and muscle outcomes, identifying gaps in current knowledge.

Neuromuscular mechanisms that contribute to gross motor performance in survivors of childhood acute lymphoblastic leukemia

PURPOSE

This study explored neuromuscular mechanisms and clinical measures that contribute to countermovement jump performance in survivors of childhood acute lymphoblastic leukemia (ALL CCS) compared to age- and sex-matched peers.

METHODS

This exploratory cross-sectional observational study examined 12 participants, six ALL CCS and six age- and sex-matched peers (7-16 years). During a countermovement jump, rates of muscle activation of lower leg muscles were measured with electromyography, and joint torques and peak jump height with force plates and a motion capture system. Clinical measures included muscle extensibility, balance, and mobility measured by active ankle dorsiflexion, Bruininks-Oseretsky Motor Proficiency (BOT-2), and Timed Up and Go (TUG) tests.

RESULTS

Compared to peers, ALL CCS demonstrated reduced gastrocnemius muscle extensibility and tibialis anterior rate of muscle activation, decreased jump height, and poorer performance on the BOT-2 and TUG. Jump height was significantly correlated with clinical measures of the BOT-2 and TUG.

CONCLUSION

These ALL CCS demonstrated neuromuscular impairments that may impact jump performance, an essential childhood physical activity. Further research is needed to explore intervention strategies to improve the neuromuscular mechanisms that contribute to high-level gross motor skills in ALL CCS.

Precision-based exercise as a new therapeutic option for children and adolescents with haematological malignancies

Children and adolescents with haematological malignancies (PedHM) are characterized by a severe loss of exercise ability during cancer treatment, lasting throughout their lives once healed and impacting their social inclusion prospects. The investigation of the effect of a precision-based exercise program on the connections between systems of the body in PedHM patients is the new frontier in clinical exercise physiology. This study is aimed at evaluating the effects of 11 weeks (3 times weekly) of combined training (cardiorespiratory, resistance, balance and flexibility) on the exercise intolerance in PedHM patients. Two-hundred twenty-six PedHM patients were recruited (47% F). High or medium frequency participation (HAd and MAd) was considered when a participant joined; > 65% or between 30% and < 64% of training sessions, respectively. The “up and down stairs'' test (TUDS), “6 min walking” test (6MWT), the “5 Repetition Maximum strength” leg extension and arm lateral raise test (5RM-LE and 5RM-ALR), flexibility (stand and reach), and balance (stabilometry), were performed and evaluated before and after training. The TUDS, the 5RM-LE and 5RM-ALR, and the flexibility exercises showed an increase in HAd and MAd groups (P < 0.05), while the 6MWT and balance tests showed improvement only in HAd group (P < 0.0001). These results support the ever-growing theory that, in the case of the treatment of PedHM, ‘exercise is medicine’ and it has the potential to increase the patient’s chances of social inclusion.

Is health status impaired in childhood cancer survivors? A systematic review and meta-analysis

BACKGROUND

An increase in survival rates of childhood cancer is associated with long-term health issues in survivors.

METHODS

We conducted a systematic review and meta-analysis comparing health status-related endpoints in childhood cancer survivors (CCS) versus controls.

RESULTS

Eighty-six studies (n = 98,480 participants, 62% CCS) were included in the review. Of these, 73 studies (n = 96,550, 63% CCS) could be meta-analyzed. CCS showed a lower left ventricular ejection and fractional shortening (SMD=-0.59 and -0.55, respectively, both p < 0.01 [n=1,824 and 1,880]), a lower HDL-cholesterol concentration (SMD=-0.48, p<0.001, n=1,378) and a higher waist-to-hip ratio (SMD=0.61, p < 0.01, n=229) than their healthy peers. No significant differences were found for the remaining endpoints.

CONCLUSIONS

CCS is associated with a lower left ventricular function and HDL-cholesterol level, and a higher waist-to-hip ratio than healthy controls. These findings support the need to closely monitor the cardiometabolic health status of CCS and to implement preventive lifestyle interventions for this population.

Identification of genetic variants associated with skeletal muscle function deficit in childhood acute lymphoblastic leukemia survivors

Background: Although 80% of childhood acute lymphoblastic leukemia (ALL) cases are cured with current treatment protocols, exposure to chemotherapeutics or radiation therapy during a vulnerable period of child development has been associated with a high frequency of late adverse effects (LAE). Previous observations suggest important skeletal muscle size, density and function deficits in ALL survivors.

Purpose: Given that only a fraction of all patients will suffer from this particular complication, we investigated whether it could be predicted by genetic markers. 

Patients and methods: We analysed associations between skeletal muscle force (Fmax) and power (Pmax) and germline genetic variants from 1039 genes derived through whole-exome sequencing. Top-ranking association signals retained after correction for multiple testing were confirmed through genotyping, and further analysed through stratified analyses and multivariate models. 

Results: Our results show that skeletal muscle function deficit is associated with two common single nucleotide polymorphisms (SNPs) (rs2001616DUOX2, P=0.0002 (Pmax) and rs41270041ADAMTS4, P=0.02 (Fmax)) and two rare ones located in the ALOX15 gene (P=0.001 (Pmax)). These associations were further modulated by sex, body mass index and risk groups, which reflected glucocorticoid dose and radiation therapy (P≤0.02). 

Conclusion: Occurrence of muscle function deficit in childhood ALL is thus strongly modulated by variations in the DUOX2, ADAMTS4 and ALOX15 genes, which could lead to personalized prevention strategies in childhood ALL survivors.

Motor function in survivors of pediatric acute lymphoblastic leukemia treated with chemotherapy-only

BACKGROUND

Up to 43% of survivors of pediatric acute lymphoblastic leukemia (ALL) may exhibit fine-motor problems. Information on manual dexterity in this cohort is still limited.

OBJECTIVES

We tested survivors of childhood ALL treated with chemotherapy-only for fine-motor function in terms of drawing and handwriting abilities using a Digitizing Tablet (DT) with three tasks for drawing and handwriting of varying complexity, for ataxia using the International Cooperative Ataxia Rating Scale (ICARS), and for tremor and hand-eye coordination using the Nine Hole Steadiness Tester (NHST).

RESULTS

We examined a cohort of non-irradiated survivors (n = 31) after a median time of 3.5 years after end of therapy. In all tasks of the DT the cohort demonstrated significant (p < 0.05) impairment of speed, automation, and variability in at least two tasks and significantly more pressure. Impaired speed (SPV) inversely correlated with lag time since end of therapy. Dexterity performance of six survivors (19%) lay below the 5th percentile. No survivor exhibited ataxia, tremor, or impaired hand-steadiness.

CONCLUSION

Despite the absence of gross ataxia, tremor, and impaired hand-eye coordination, we nevertheless detected significant fine-motor impairment in a relevant number of survivors of childhood ALL. Prospective studies are needed to reveal the pathophysiological underpinnings and genetic risk factors for development of such deficits due to ALL and its treatment.

Exercise program for children and adolescents with leukemia and lymphoma during treatment: A comprehensive review

An exercise program (EP) during cancer treatment seems to be a valid strategy against physiological and quality-of-life impairments, but scientific evidence of benefits among pediatric patients is still limited. This review summarizes the literature focused on randomized controlled trials of EP offered to patients during leukemia and lymphoma treatment. Studies published up to June 2017 were selected from multiple databases and assessed by three independent reviewers for methodological validity. The review identified eight studies, but several types of bias have to be avoided to provide evidence-based recommendations accessible to patients, families, and professionals.

Physical training interventions for children and teenagers affected by acute lymphoblastic leukemia and related treatment impairments

A decreased physical fitness has been reported in patients and survivors of acute lymphoblastic leukemia (ALL). This is influenced by the negative effects of the disease and by the treatments of childhood cancer.

In the past, children were advised to recover in bed, and to take as much relax as possible. Nowadays, it is considered that too much immobility may result in a further decrease of physical fitness and functioning. Exercise training for ALL children has frequently been reported to improve physical fitness and the well-being of the children, since it prevents the negative effects of a sedentary life-style, such as obesity and a poor skeletal health. In recent years, different studies and protocols on this subject has become available for children and young adults with cancer, both during and after treatment.

The efficacy of recent physical exercise training interventions, that act on several ALL impairments in children such as skeletal, musculoskeletal, neuromuscular, cardiopulmonary and cardiovascular systems, fatigue, body balance disorders and metabolism alterations have been examined.

These side effects might be prevented or significantly reduced by introducing a physical exercise program during or shortly after cancer treatment. Several interventions are discussed and presented for each impairment, reducing their level caused by the disease and thus suggesting the importance of physical training activity in ameliorating the children quality of life.

Muscle strength and quality of life in patients with childhood cancer at early phase of primary treatment

Cancer- and treatment-related side effects in patients with childhood cancer may cause limitations in motor performance affecting activities of daily living (ADLs). Data focusing on long-term effects are available, but little is known with regard to the short-term perspective. Therefore, the purpose of this study was to assess muscle strength performance and quality of life (QoL) in children and adolescents with cancer at the beginning of primary treatment. Forty children and adolescents aged 5-18 years (mean: 11.39 ± 4.08 years) with different types of childhood cancer were enrolled. On average 36 ± 20.5 days after diagnosis, strength performance in 7 muscle groups was assessed by handheld dynamometry. KINDL questionnaires were completed to evaluate QoL (children's self-report and parents' report). All parameters were compared with age- and gender-matched reference values. Patients with childhood cancer showed significantly lower strength values in all muscle groups (P < .01) compared with age- and gender-matched controls. Most affected were the lower extremities, with a -57.1% ± 10.4%, median: -59.2%, minimum: -75.4%, maximum: -41.4% percentage deviation in knee flexion from healthy peers. Children themselves and parents assessed total QoL significantly below age- and gender-matched reference values (P < .01). Correlation between elbow flexion and self-reported QoL was detected. Broader correlations were found for the parents' report. Muscle weakness and decreased QoL in children and adolescents seem to persist already at the beginning of anticancer treatment. This underlines the need of counteracting measures, such as exercise intervention programs, starting as early as possible during the treatment process. Efforts on this topic are currently being carried out by our group.