This study aimed to examine the effect of individual dietary intervention on nutrition and oxidative stress of patients with type 2 diabetes mellitus (T2DM) complicated by pulmonary tuberculosis (PTB) in Xinjiang.
Methods
A total of 164 patients with T2DM and PTB from January 2018 to December 2018 in the Chest Hospital of Xinjiang Uyghur Autonomous Region were included. According to the random number table method, the patients were divided into an experimental group (n = 82) and control group (n = 82). The original treatments of PTB and T2DM were maintained. The control group was treated with a self-controlled diet, while the experimental group was treated with an individual quantitative dietary intervention. All patients included in our study were closely followed up for 3 months and the serum levels of variables related to nutrition, oxidative stress, and blood glucose were measured to compare each patient’s nutritional and oxidative stress after the intervention. Proportions of patients with sputum testing positive for bacteria before and after the intervention were also recorded and compared between the two groups.
Results
There were no significant differences between the two groups with regard to age, sex, labor intensity, marital status, course and treatment of diabetes, and proportion of patients with sputum positive for bacteria before the intervention (P > 0.05). There were statistically significant differences between the two groups in variables to related nutrition and oxidative stress, especially SOD which was increased by 13.2% in the experimental group and 2.5% in the control group after intervention (P < 0.05). The proportion of patients with sputum positive for bacteria in the experimental group was significantly lower than that in the control group, and the difference was statistically significant (P < 0.05).
Conclusion
A combination of individual quantitative dietary interventions can improve the nutritional status of patients with T2DM–PTB and adjust the oxidative stress. This method provides a theoretical basis for a reasonable diet in patients with T2DM–PTB.
Trial Registration
ChiCTR900025477 (Retrospectively registered).
Hinweise
Liyun He and Guoming Zhang are the co-first authors.
Diabetes is a metabolic endocrine disease. Latest data from the World Diabetes Foundation (WDF) (2015) show that the number of adult patients with diabetes worldwide is expected to increase from 415 million to 642 million by 2040, with the majority of patients in developing countries [1]. The prevalence of type 2 diabetes mellitus (T2DM) among Xinjiang residents was 14%; this is much higher than the average prevalence in China [2]. Pulmonary tuberculosis (PTB) is a chronic pulmonary infectious disease caused by Mycobacterium tuberculosis (MTB) complex flora and is often accompanied by varying degrees of malnutrition. Latest data show that tuberculosis prevalence is still very high in China, ranking third in the world behind India and Indonesia [3]. At present, approximately 500 million people are infected with MTB in China, and approximately 1.5 million new cases are reported every year [4]. Tuberculosis shows the characteristics of high infection, morbidity, and drug resistance rates in China [5].
Patients with T2DM are at high risk of PTB infection [6]. PTB is a common complication of T2DM [7], and it can aggravate the glucose metabolism disorder in patients with T2DM, increase the incidence of ketoacidosis, and the prognosis is poor. Patients with T2DM have increased glucose levels in blood and tissues, impairing protein and fat metabolism, which is conducive to the growth and reproduction of MTB, and more susceptible to multiple drug-resistant strains, which worsens the condition of patients with PTB [8]. In patients with T2DM–PTB, there are often systemic metabolic disorders, acid–base imbalance, negative nitrogen balance, and malnutrition; protein catabolism is increased significantly, resulting in excessive protein consumption, reduced nutritional intake, reduced protein synthesis and metabolism, and protein-energy malnutrition (PEM) is prone to occur. The incidence of PEM is 42.1–86.3% [9]. The prognosis of PEM depends first on whether T2DM is controlled, and secondly on the severity of PTB. There are homogeneity and differences in dietary treatment. Dietary control of patients with T2DM should take into account the nutritional needs of PTB. On the contrary, the nutritional conditions of PTB should be adjusted under the conditions of caloric balance of T2DM.
Anzeige
This prospective controlled study aimed to examine the nutritional and oxidative stress status of patients with T2DM–PTB in Xinjiang. It will assist nutritionists in formulating personalized diets for patients according to patients’ preferences. The purpose is to achieve the goal of enhancing patients’ resistance and immunity, reducing adverse outcomes, and improving survival rate and quality of life.
Methods
Ethics
A total of 164 patients with T2DM–PTB were enrolled in this study in the Thoracic Hospital of Xinjiang Uyghur Autonomous Region from January 2018 to December 2018. All selected patients voluntarily participated in the study. The study was examined and approved by the Ethics Committee of the First Affiliated Hospital of Xinjiang Medical University. All procedures performed in studies involving human participants were in accordance with the ethical standards of our local ethics committee (the Ethics Committee of the First Affiliated Hospital of Xinjiang Medical University) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study. Prior to providing informed consent, all subjects were informed of the study objectives and the risks and benefits of the study. All subjects were given sufficient time to decide whether they would like to participate in the trial.
Inclusion and Exclusion Criteria
The inclusion criteria are (1) those who met the diagnostic criteria of the Chinese Guidelines for the Prevention and Treatment of Type 2 Diabetes Mellitus (2017 edition) [10] (fasting venous blood glucose > 7.0 mmoL/L, or postprandial oral glucose tolerance 2 h venous blood glucose > 11.1 mmol/L, or random venous blood glucose > 11.1 mmol/L; if no symptoms of diabetes mellitus, above mentioned tests have to be repeated in the same day); (2) those who met the diagnostic criteria of PTB (met the diagnostic criteria of WS288-2017 of China Health Planning Commission [11]; chest X-ray and computed tomography (CT) showed typical tuberculosis lesions; or sputum smear tested positive for acid-fast bacilli); (3) diabetes was diagnosed prior to PTB detection; (4) patients are actively on oral hypoglycemic treatment and/or insulin injections with anti-TB medication (isoniazid (H), rifampicin (R), pyrazinamide (Z), and ethambutol (E) (2H R Z E/4H R [12]; a combination of H, R, Z, and E for the first 2 months, followed by a combination of H and R for the next 4 months); (5) patients aged 18–70 years with full consciousness and voluntarily participated in the study, and who signed informed consent; (6) patients who cooperated with and insisted on the study duration and to provide complete dietary records, and who had no previous history of mental illness.
Study Design
A total of 164 patients with T2DM–PTB were randomly divided into control group and experimental group with 82 cases in each group. The two groups were on the same anti-TB regimen and asked to insist on daily anti-TB medication. Sputum smear, chest X-ray, and liver and kidney functions were regularly checked. The control group adopted a self-controlled diet and the experimental group received individualized dietary interventions; both groups were on their diet for 3 months.
Anzeige
All enrolled patients were instructed and guided by professional trained medical stuff to complete the informed consent forms, demographic data questionnaires, NRS (nutrition risk screening) 2002 assessment forms, 3-day dietary diaries, and food frequency questionnaires, and given further explanation if the patients had any doubts. Patients in the experimental group received routine dietary nursing and health education once a week about dietary nutrition and a detail-oriented handbook.
Total daily calorie intake and proportions of three nutritional elements (sugar, protein, and fat) were calculated on the basis of individual body shape and labor strength. The conventional diabetic diet (non- individualized) was used in the control group and an individualized dietary recipe was applied in the experimental group. A detailed study algorithm is shown in Fig. 1.
Fig. 1
Study algorithm
×
Intervention Program of Control Group
The intervention program of the control group includes calculating each patient’s standard weight, total daily calories, and formulating recipes. Patients can formulate specific recipes according to their own dietary preferences and they were educated about alternative dietary choices and instructed by professionally trained medical stuff.
Intervention Program of Experimental Group
Investigation of Patients’ Dietary Status
Using food frequency surveys, patients in the experimental group were asked about their daily-life dietary patterns and structures; unreasonable and unhealthy dietary habits were corrected, the Dietary Health Education Manual for Type 2 Diabetes Mellitus with Tuberculosis” was delivered to each patient, and they were educated about basic knowledge of the disease. The food frequency questionnaire used in this study basically covered the types of food that Xinjiang residents usually consume and incorporated the local characteristics of Xinjiang. Uyghur foods such as steamed bread, soup rice, Naren, mixed noodles, grabbing rice, barbecue, and so on were added to the original questionnaire.
Maintenance of Dietary Diary by Patient or Their Family Members
Study participants were asked for dietary records of three consecutive days prior to intervention; the patients and their relatives were also trained how to record their own diets. The accuracy of these records was checked by professionally trained medical stuff. A 3-day dietary diary was used for recording (once in the week and once at the weekend). The results were averaged to reflect the daily dietary levels of the patients and to lay a foundation for individualized dietary plans for these patients.
On the basis of the patient’s physical measurements, nutritional and economic status, blood sugar level, individual comprehensive situation, etc., a “nutrition calculator” was used to calculate the 24-h energy intake and nutrient levels; these values were then compared with the reference dietary nutrient intake values in Chinese residents to formulate a scientific combination for each individual—a rational dietary intervention program. According to the nutritional requirements of the program, a weekly personalized quantitative diet is listed to facilitate patients’ choice at home, and the diet is adjusted step by step according to the results of blood sugar monitoring.
According to TB status, the total calorie intake is slightly higher than about 10% of the diabetic calorie balance, and the amount of food exchanged daily is calculated. Carbohydrates and fats accounted for 55–65% and 20–25% of the total energy intake, respectively; an appropriate increase was observed in protein intake, accounting for more than 15% of the total energy intake (1.5–2.0 g/kg protein per person per day, of which high-quality protein accounted for half to two-thirds of the total protein). In order to supplement extra energy consumption due to fever and night sweats, intake of vegetables (300–500 g/day) and fruits (100–200 g/day) was suggested; to increase antioxidant and trace element intake, we suggested ingestion of fresh vegetables that are rich in various vitamins and yellow-green foods that are rich in chromium and calcium (calcium intake was higher than the recommended 800 mg/day). While choosing food, we also referred to the glycogenesis index and load of each food item and chose some foods with lower glycemic index (GI) and glycemic load (GL), which is easier to grasp.
Evaluation Indicators
1.
Oxidative stress indicators: superoxide dismutase (SOD), malondialdehyde (MDA), vitamin C, and vitamin E. Human Superoxide Dismutase (SOD) ELISA Kit, catalogue number JYM2065Hu.
Human MDA ELISA Kit, catalogue number JYM0375Hu. For the quantitative in vitro determination of active SOD in human serum, plasma, culture media, or any biological fluid. The SOD is total superoxide dismutase.
Fasting peripheral venous blood was collected in the morning and centrifuged at 1500×g for 15 min within 60 min of collection. The separated serum was stored in a refrigerator at − 80 °C. SOD, MDA, vitamin C, and vitamin E detection kits were purchased from Xinjiang Yingjie Leading Biotechnology Co. Ltd.; enzyme-linked immunosorbent assays (ELISAs) were performed by strictly referring to the kit instructions. The kit involved a double-antibody one-step sandwich ELISA technique. Pre-coated antibodies that captured human SOD were coated on the micropore base; samples, standards, and horseradish peroxidase (HRP)-labeled antibodies were added in turn, after incubation and thorough washing. Tetramethylbenzidine (TMB) was used as the substrate; reaction of peroxidase with TMB produced a blue-colored compound that turned yellow on reaction with acid. The depth of color was positively correlated with human superoxide dismutase levels in the samples. Absorbance (OD) was measured at a wavelength of 450 nm with the enzyme-labeling instrument and sample concentrations were calculated.
2.
Nutritional indicators: serum albumin, hemoglobin, total lymphocyte count (TLC), and body mass index (BMI).
Tuberculosis control index: positive bacterial counts in the sputum.
5.
C-peptide: radioimmunoassay was used to test the plasma level of C-peptide
Statistical Analysis
Statistical analysis was carried out using the SPSS 17.0 software. Continuous variables were expressed as mean ± standard deviation. Statistical data conforming to normal distribution were tested using t test of two independent samples and chi-square test. The significance level was set as P < 0.05.
Results
A total of 164 patients completed the study. Ten patients (five in each group) were lost to follow-up and excluded from the study. The mean (SD) age was 58.94 ± 12.12 years in the experiment group and 60.62 ± 12.26 years in the control group. There were no significant differences between the two groups with regard to age, sex, labor intensity, marital status, and course and treatment of diabetes. At baseline there were no differences between the groups in any of the study variables (Table 1).
Table 1
Comparison of demographic data between the two groups (n = 164)
Index
Group
Control group (n = 82)
Experimental group (n = 82)
χ2
P
n
%
n
%
Age (years)
18–40
18
56.3
14
43.8
1.672
0.433
41–59
31
44.3
39
55.7
≥ 60
33
53.2
29
46.8
Sex
Male
49
52.1
45
47.9
0.399
0.528
Female
33
47.1
37
52.9
Labor intensity
Light
45
46.9
51
53.1
0.995
0.608
Medium
25
53.2
22
46.8
Heavy
12
57.1
9
42.9
Marital status
Married
65
80.0
70
85.4
0.837
0.360
Unmarried
17
20.0
12
14.6
Diabetes treatment
Hypoglycemic drug
21
46.7
24
53.3
1.106
0.575
Insulin injection
35
47.9
38
52.1
Hypoglycemic drug + insulin injection
26
56.5
20
43.5
Disease course (years)
≤ 5
20
24.4
23
28.0
0.470
0.791
6–10
27
32.9
28
34.1
≥ 11
35
42.7
31
37.8
All variables related to nutrition and oxidative stress were comparable between the two groups before intervention. We observed a significant elevation in ALB, Hb, TLC, BMI, SOD, VC, VE, and TCI (P < 0.05) and decrease in MDA, FPG, 2hPG, and HbA1c (P < 0.05) (Table 2).
Table 2
Comparison of variables related to nutrition and oxidative stress between the two groups before and after intervention (\( \bar{x} \pm s \), n = 164)
Control group (n = 82)
Experimental group (n = 82)
t
P
ALB (mg/dL)
Before intervention
3627.00 ± 465
3533.00 ± 478
1.28
0.20
After intervention
3829.00 ± 371
4007.00 ± 426
− 2.85
0.01
Hb (mg/dL)
Before intervention
11,487.00 ± 906
11,524.00 ± 1185
− 0.23
0.82
After intervention
12,038.00 ± 1134
12,474.00 ± 1272
− 2.32
0.02
TLC (× 109/L)
Before intervention
1.47 ± 0.51
1.53 ± 0.38
− 0.73
0.47
After intervention
1.61 ± 0.53
1.78 ± 0.45
− 2.35
0.02
BMI
Before intervention
22.08 ± 0.97
22.45 ± 1.61
− 1.79
0.08
After intervention
22.63 ± 0.99
23.05 ± 1.25
− 2.40
0.02
SOD (U/ml)
Before intervention
315.03 ± 93.42
303.28 ± 76.02
0.88
0.38
After intervention
323.40 ± 57.34
343.82 ± 53.32
− 2.36
0.02
MDA (nmol/ml)
Before intervention
6.45 ± 1.77
6.00 ± 1.45
1.77
0.08
After intervention
5.85 ± 1.70
5.34 ± 1.42
2.09
0.04
VC (μmol/L)
Before intervention
39.24 ± 6.09
38.97 ± 7.10
0.26
0.80
After intervention
41.45 ± 4.85
43.30 ± 6.39
− 2.08
0.04
VE (μmol/L)
Before intervention
17.23 ± 6.51
17.56 ± 5.98
− 0.34
0.74
After intervention
19.19 ± 4.74
20.86 ± 5.34
− 2.11
0.04
FPG (mmol/L)
Before intervention
10.82 ± 1.64
10.35 ± 1.70
1.83
0.07
After intervention
8.89 ± 1.98
8.09 ± 1.64
2.82
0.01
2hPG (mmol/L)
Before intervention
14.53 ± 2.72
14.74 ± 2.63
− 0.51
0.61
After intervention
11.43 ± 1.94
10.61 ± 1.77
2.84
0.01
HbA1c (%)
Before intervention
10.50 ± 2.19
10.38 ± 2.05
0.34
0.74
After intervention
8.87 ± 1.96
8.13 ± 1.83
2.51
0.01
C-peptide (ng/ml)
Before intervention
1.49 ± 0.93
1.61 ± 0.85
0.86
0.39
After intervention
1.32 ± 0.94
1.03 ± 0.57
2.39
0.01
TCI [kcal/(kg day)]
Before intervention
1494.71 ± 212.18
1535.02 ± 228.27
1.17
0.24
After intervention
1691.12 ± 245.25
1784.76 ± 252.08
2.41
0.01
ALB albumin, Hb hemoglobin, TLC total lymphocyte count, BMI body mass index, SOD superoxide dismutase, MDA malondialdehyde, VC vitamin C, VE vitamin E, FPG fasting plasma glucose, 2hPG 2-h plasma glucose, HbA1c glycated hemoglobin, TCI total calorie intake
The proportion of patients with sputum positive for bacteria was significantly lower in the experimental group than that in the control group after intervention (Table 3).
Table 3
Comparison of proportion of patients with sputum positive for bacteria between the two groups before and after intervention, n (%)
Group
n
Before intervention
After intervention
Control group
82
34 (41.5%)
23 (28%)
Experimental group
82
27 (32.9%)
12 (14.6%)
χ2
1.28
4.4
P
0.26
0.04
Anzeige
Discussion
In this study, the incidence of hypoproteinemia and lymphopenia was higher in the two groups before intervention, suggesting that patients with T2DM–PTB have more severe visceral protein consumption. Studies have found that the degree of nutritional deficiencies gradually increases and albumin deficiency becomes more serious as the disease progresses [13]. The overall albumin level is low because of insufficient insulin secretion in patients with diabetes, so they cannot fully utilize glucose and need to break down proteins and fats to provide calories [14]. Tuberculosis is a chronic nutrient-consumption disease; patients with TB usually experience gastrointestinal dysfunction which results in less nutrient intake and insufficient anabolism [13], but patients with TB usually also experience consumptive symptoms such as fever and night sweats which result in increased catabolism [15]. Therefore, the synthesis of albumin is reduced. Patients with T2DM–PTB experience long-term nutritional overconsumption status and loss of appetite which leads to malnutrition in the body, malnutrition causes damage to cellular immune function, which can cause a decrease in TLC and an increase in the number of T cells, and a decrease in the ratio of helper T cells to suppressor T cells [16]. TB lesions in the lung tissue can lead to the occurrence of infectious anemia [17]. The dietary plan formulated in this study considers not only maintaining the stability of the patient’s glucose level but also ensuring adequate nutrition and correcting the possible anemia. After 3 months of individual quantitative dietary intervention and intensive health education, serum albumin, total lymphocyte count, hemoglobin, and body mass index of the experimental group were significantly higher than those in the control group, indicating that individual quantitative dietary intake can improve serum albumin level and promote lymphocyte proliferation, significantly improve nutritional status, and improve treatment effect. In addition, the proportion of patients with sputum positive for bacteria in the experimental group was significantly lower than that in the control group, indicating that individualized dietary intervention and intensive health education have a positive impact on disease control in patients with T2DM–PTB.
This study showed that after the intervention, the antioxidant enzyme activity in the experimental group such as SOD, VC, and VE were higher than that in the control group. Oxidative stress responses in the body are more intense as the condition of T2DM–PTB progresses and the nutritional status declines. Reasonable dietary intervention for patients with T2DM–PTB can enhance their nutritional status and reduce or avoid oxidative stress and reduce complications. As the ability of antioxidative stress is enhanced, the MDA content is significantly lower in the experimental group than that in the control group, which can remarkably improve the ability of scavenging free radicals in the body. It is fully proved that antagonizing oxidative stress is of great significance for the prevention and treatment of chronic complications of diabetes. Oxidative stress intervention is expected to become one of the new means of preventing diseases.
The level of oxidative stress in patients with pulmonary tuberculosis may increase the production of reactive oxygen species (ROS) due to the inflammatory reaction in the body [18], leading to an imbalance of oxidative stress and aggravation of oxidative damage. High-glucose environments can induce the production of ROS, which increases the oxidative stress of the body and aggravates the condition of DM [19]. The level of oxidative stress may be higher in patients with T2DM–PTB. The free radicals and lipids in the organism undergo peroxidation, and the final product is MDA, which can cause cross-linking polymerization of macromolecules such as proteins and nucleic acids which is cytotoxic [20]. Excessive MDA can attack DNA, protein, glycolipids, etc., causing damage and inducing various diseases [21]. This imbalance can exacerbate oxidative damage, which can lead to increased intracellular oxidative stress. It has been confirmed in human and animal experiments [22] that elevated levels of intercellular and intracellular blood glucose will lead to increased levels of oxidative stress. As pancreatic beta cells are exposed to high glucose concentrations, the islet secretion is destroyed gradually.
Studies [22, 23] have confirmed that blood glucose fluctuations in patients with diabetes are significantly associated with oxidative stress, and lowering blood glucose can enhance the ability of antioxidant systems in the body. Protection of cells can be achieved through SOD by removing excess superoxide anion radical (O2·−), so that they will not be destroyed under the influence of external circumstances. Fresh vegetables and fruits contain VE and VC which have antioxidant effects [24]. SOD, VE, and VC constitute an antioxidant network and these antioxidants can be regenerated and recycled through interaction, and this antioxidant network is usually activated by VE.
Anzeige
Compared with the control group, the fasting blood glucose, the 2-h postprandial blood glucose, and glycated hemoglobin level were significantly reduced in the experiment group after 3 months of dietary intervention which achieved our therapeutic goal. In the experimental group, dietary intervention fully considered the dual effects of drugs and food on the patient’s blood glucose level. By controlling and adjusting the quality and quantity of food intake, the effect of drug interaction on blood glucose, and the intake of three nutrients were strictly calculated. Dietary intervention therapy plays an important role in controlling body mass index, improvement of islet function, regulating blood glucose and lipid levels, and can control blood glucose level by regulating genes associated with obesity. Intake of a low GI and GL diet can improve blood glucose level which rises slowly and decreases demand for insulin; long-term intake of a low GI and GL diet can reduce post-prandial intestinal hormone and insulin, slow down the rate of carbohydrate absorption [25], inhibit blood free fatty acid levels, antagonize the response of hormones, and accelerate the clearance of glucose in the blood, thereby reducing the burden of beta cells. In addition, in order to prolong the absorption time of glucose in the small intestine, it is necessary to follow a low GI and low GL diet for a long period of time, and the continuous inhibition of blood free fatty acid level and reaction to hormones can produce significant antagonism and reduce blood glucose level [26]. The results of the study confirmed that [25] a reasonable diet structure, especially after increasing the proportion of protein (average 3–5% higher than in normal people), has little effect on blood glucose level, but improves insulin sensitivity and glucose tolerance.
There was no significant difference in plasma level of C-peptide values between the two groups before intervention, and there was a significant decrease after intervention. At the same time, the plasma level of C-peptide in the experimental group was significantly lower than that of the control group. C-peptide has an anti-inflammatory effect and reduces the expression of cell adhesion molecules on the surface of vascular endothelial cells under inflammatory conditions. The combination of C-peptide and insulin can inhibit endothelial cell apoptosis induced by high glucose and improve vascular endothelium [27]. After a 3-month personalized diet intervention program, total energy intake was increased in the experimental group, which improved the patient’s dietary structure and the total energy intake, and achieved the principle of the balanced diet.
Conclusion
By including a special group of patients with T2DM–PTB in Xinjiang, China, as the study population, this study examines the effects of individual dietary intervention combined with intensified health education intervention strategy; this method can integrate the language and cultural background of patients of all ethnic groups in Xinjiang as well as the psychological states of all patients and guide them in improving their dietary intake structure reasonably. Improving the level of dietary diversification and long-term quality of life of patients is of certain clinical value. In addition, patients with T2DM–PTB have better prognoses and quality of life if they receive adequate health education with proper dietary intervention and if the intervention follow-up is longer. Because of the short observation time in this study, it is impossible to further evaluate the effect of dietary intervention on the overall survival rate of the patients. Therefore, in future studies, we need to further analyze whether any other factors affect oxidant–antioxidant imbalance and malnutrition in these patients and adopt more individualized and targeted measures.
Acknowledgements
We are very grateful to our study participants for their participation.
Anzeige
Funding
Sponsorship for this study and the Journal’s Rapid Service Fee were funded by a grant from the Natural Science Foundation of Xinjiang Uygur Autonomous Region (2015211C061).
Authorship
All named authors meet the International Committee of Medical Journal. Editors (ICMJE) criteria for authorship for this article, take responsibility for the integrity of the work as a whole, and have given their approval for this version to be published.
Disclosures
Liyun He, Guoming Zhang, Meng Wei, Yanjun Zhao, Weixing Chen, Qiaojun Peng, and Guiyun Meng have nothing to disclose.
Compliance with Ethics Guidelines
All procedures performed in studies involving human participants were in accordance with the ethical standards of our local ethics committee (the Ethics Committee of the First Affiliated Hospital of Xinjiang Medical University) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.
Data Availability
The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.
Open Access
This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
