[Distribution and reference intervals of daytime intraocular pressure in the eye health screening population of Handan].

Objective: To describe the distribution and establish reference intervals (RI) of daytime intraocular pressure (IOP) in the eye health screening population of Handan. Methods: This cross-sectional study included subjects who participated in eye health screening at the Physical Examination Center of Handan First Hospital from May 2021 to June 2022. A complete general and ocular examination was performed, including measurements of visual acuity and IOP (using Goldmann tonometry), slit lamp microscopy, fundus photography, and anterior and posterior segment optical coherence tomography. Subjects with factors that could cause significant changes in IOP or affect the accuracy of IOP measurement, or with an inability to measure IOP were excluded. Simple random sampling was used to select participants, who were grouped by gender and age (18 to <30, 30 to <40, 40 to <50, 50 to <60, 60 to <70, and ≥70 years). Central corneal thickness and IOP at 8 to 11 o'clock in one eye of each participant were recorded. The independent sample t test and ANOVA were used for statistical analysis, and the RI of IOP values was calculated by x¯±1.96s. Results: A total of 9 310 subjects had their IOP measured, and 3 491 participants (3 491 eyes) were randomly selected from 7 886 healthy subjects. The age of the participants was (47.74±14.47) years old, ranging from 18 to 90 years old. There were 1 694 males and 1 797 females. The central corneal thickness of all participants was (525.56±49.39) µm. The daytime IOP of all participants was (15.40±2.54) mmHg (1 mmHg=0.133 kPa), and the RI was 10.42 to 20.39 mmHg. The IOP was (15.49±2.58) mmHg for males and (15.29±2.49) mmHg for females, and the gender difference was statistically significant (P<0.05). The RI of daytime IOP values was 10.43 to 20.54 mmHg for males and 10.41 to 20.18 mmHg for females. There were significant differences in daytime IOP [(15.13±2.58), (15.33±2.53), (15.49±2.50), (15.53±2.55), (15.39±2.62), and (15.28±2.52) mmHg] among 6 age groups (P<0.05). Conclusions: The distribution of daytime IOP in different gender and age groups in the eye health screening population of Handan and the RIs derived from the distribution were roughly the same as the international normal IOP RI (10 to 21 mmHg). It is recommended to refer to the RI of daytime IOP values of different genders and ages for clinical decision.

Structural responses of metallic glasses under neutron irradiation.

Seeking nuclear materials that possess a high resistance to particle irradiation damage is a long-standing issue. Permanent defects, induced by irradiation, are primary structural changes, the accumulation of which will lead to structural damage and performance degradation in crystalline materials served in nuclear plants. In this work, structural responses of neutron irradiation in metallic glasses (MGs) have been investigated by making a series of experimental measurements, coupled with simulations in ZrCu amorphous alloys. It is found that, compared with crystalline alloys, MGs have some specific structural responses to neutron irradiation. Although neutron irradiation can induce transient vacancy-like defects in MGs, they are fully annihilated after structural relaxation by rearrangement of free volumes. In addition, the rearrangement of free volumes depends strongly on constituent elements. In particular, the change in free volumes occurs around the Zr atoms, rather than the Cu centers. This implies that there is a feasible strategy for identifying glassy materials with high structural stability against neutron irradiation by tailoring the microstructures, the systems, or the compositions in alloys. This work will shed light on the development of materials with high irradiation resistance.

Staphylococcus aureus interaction with Pseudomonas aeruginosa biofilm enhances tobramycin resistance.

Antimicrobial resistance is a significant threat to the treatment of infectious disease. Multiple mechanisms of resistance to different classes of antibiotics have been identified and well-studied. However, these mechanisms are studied with bacteria in isolation, whereas often, infections have a polymicrobial basis. Using a biofilm slide chamber model, we visualized the formation and development of clinical Pseudomonas aeruginosa biofilms in the presence of secreted Staphylococcus aureus exoproducts, two bacteria that commonly co-infect pediatric patients with cystic fibrosis. We showed that, over time, certain isolates of P. aeruginosa can form different biofilm architecture in the presence of S. aureus exoproducts. We further determined that this interaction was dependent on Psl produced by P. aeruginosa and staphylococcal protein A from S. aureus. Importantly, we identified a mechanism of antibiotic resistance to tobramycin that is dependent on the polymicrobial interactions between these two bacteria. This interaction occurred in isolates of P. aeruginosa recovered from children with cystic fibrosis who failed to clear P. aeruginosa following inhaled tobramycin treatment.

The adaptive decision-making, risky decision, and decision-making style of Internet gaming disorder.

BACKGROUND: Persistent gaming, despite acknowledgment of its negative consequences, is a major criterion for individuals with Internet gaming disorder (IGD). This study evaluated the adaptive decision-making, risky decision, and decision-making style of individuals with IGD. METHODS: We recruited 87 individuals with IGD and 87 without IGD (matched controls). All participants underwent an interview based on the Diagnostic and Statistical Manual of Mental Disorders (5th Edition) diagnostic criteria for IGD and completed an adaptive decision-making task; the Preference for Intuition and Deliberation Scale, Chen Internet Addiction Scale, and Barratt Impulsivity Scale were also assessed on the basis of the information from the diagnostic interviews. RESULTS: The results demonstrated that the participants in both groups tend to make more risky choices in advantage trials where their expected value (EV) was more favorable than those of the riskless choice. The tendency to make a risky choice in advantage trials was stronger among IGD group than that among controls. Participants of both groups made more risky choices in the loss domain, a risky option to loss more versus sure loss option, than they did in the gain domain, a risky option to gain more versus sure gain. Furthermore, the participants with IGD made more risky choices in the gain domain than did the controls. Participants with IGD showed higher and lower preferences for intuitive and deliberative decision-making styles, respectively, than controls and their preferences for intuition and deliberation were positively and negatively associated with IGD severity, respectively. CONCLUSIONS: These results suggested that individuals with IGD have elevated EV sensitivity for decision-making. However, they demonstrated risky preferences in the gain domain and preferred an intuitive rather than deliberative decision-making style. This might explain why they continue Internet gaming despite negative consequences. Thus, therapists should focus more on decision-making styles and promote deliberative thinking processes to mitigate the long-term negative consequences of IGD.

Mitochondrial DNA variants as genetic risk factors for Parkinson disease.

BACKGROUND AND PURPOSE: Investigation of the relationship between mitochondrial DNA (mtDNA) variants and Parkinson disease (PD) remains an issue awaiting more supportive evidence. Moreover, an affirming cellular model study is also lacking. METHODS: The index mtDNA variants and their defining mitochondrial haplogroup were determined in 725 PD patients and 744 non-PD controls. Full-length mtDNA sequences were also conducted in 110 cases harboring various haplogroups. Cybrid cellular models, composed by fusion of mitochondria-depleted rho-zero cells and donor mitochondria, were used for a rotenone-induced PD simulation study. RESULTS: Multivariate logistic regression analysis revealed that subjects harboring the mitochondrial haplogroup B5 have resistance against PD (odds ratio 0.50, 95% confidence interval 0.32-0.78; P = 0.002). Furthermore, a composite mtDNA variant group consisting of A10398G and G8584A at the coding region was found to have resistance against PD (odds ratio 0.50, 95% confidence interval 0.33-0.78; P = 0.001). In cellular studies, B4 and B5 cybrids were selected according to their higher resistance to rotenone, in comparison with cybrids harboring other haplogroups. The B5 cybrid, containing G8584A/A10398G variants, showed more resistance to rotenone than the B4 cybrid not harboring these variants. This is supported by findings of low reactive oxygen species generation and a low apoptosis rate in the B5 cybrid, whereas a higher expression of autophagy was observed in the B4 cybrid particularly under medium dosage and longer treatment time with rotenone. CONCLUSIONS: Our studies, offering positive results from clinical investigations and cybrid experiments, provide data supporting the role of variant mtDNA in the risk of PD.

More inclusive bipolar mixed depression definition by permitting overlapping and non-overlapping mood elevation symptoms.

OBJECTIVE: The objective of this study was to assess the strengths and limitations of a mixed bipolar depression definition made more inclusive than that of the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) by counting not only 'non-overlapping' mood elevation symptoms (NOMES) as in DSM-5, but also 'overlapping' mood elevation symptoms (OMES, psychomotor agitation, distractibility, and irritability). METHODS: Among bipolar disorder (BD) out-patients assessed with the Systematic Treatment Enhancement Program for BD (STEP-BD) Affective Disorders Evaluation, we assessed prevalence, demographics, and clinical correlates of mixed vs. pure depression, using more inclusive (≥3 NOMES/OMES) and less inclusive DSM-5 (≥3 NOMES) definitions. RESULTS: Among 153 depressed BD, counting not only NOMES but also OMES yielded a three-fold higher mixed depression rate (22.9% vs. 7.2%) and important statistically significant clinical correlates for mixed compared to pure depression (more lifetime anxiety disorder comorbidity, more current irritability, and less current antidepressant use), which were not significant using the DSM-5 threshold. CONCLUSION: To conclude, further studies with larger numbers of patients with DSM-5 bipolar mixed depression assessing strengths and limitations of more inclusive mixed depression definitions are warranted, including efforts to ascertain whether or not OMES should count toward mixed depression.

Agrobacterium-mediated transformation of the ß-subunit gene in 7S globulin protein in soybean using RNAi technology.

The objective of this study was to use RNA interference (RNAi) to improve protein quality and decrease anti-nutritional effects in soybean. Agrobacterium tumefaciens-mediated transformation was conducted using RNAi and an expression vector containing the 7S globulin ß-subunit gene. The BAR gene was used as the selective marker and cotyledonary nodes of soybean genotype Jinong 27 were chosen as explant material. Regenerated plants were detected by molecular biology techniques. Transformation of the ß-subunit gene in the 7S protein was detected by PCR, Southern blot, and q-PCR. Positive plants (10 T0, and 6 T1, and 13 T2) were tested by PCR. Hybridization bands were detected by Southern blot analysis in two of the T1 transgenic plants. RNAi expression vectors containing the soybean 7S protein ß-subunit gene were successfully integrated into the genome of transgenic plants. qRT-PCR analysis in soybean seeds showed a clear decrease in expression of the soybean ß-subunit gene. The level of 7S protein ß-subunit expression in transgenic plants decreased by 77.5% as compared to that of the wild-type plants. This study has established a basis for the application of RNAi to improve the anti-nutritional effects of soybean.

More inclusive bipolar mixed depression definitions by requiring fewer non-overlapping mood elevation symptoms.

OBJECTIVE: Assess strengths and limitations of mixed bipolar depression definitions made more inclusive than that of the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) by requiring fewer than three 'non-overlapping' mood elevation symptoms (NOMES). METHOD: Among bipolar disorder (BD) out-patients assessed with Systematic Treatment Enhancement Program for BD (STEP-BD) Affective Disorders Evaluation, we assessed prevalence, demographics, and clinical correlates of mixed vs. pure depression, using less inclusive (≥3 NOMES, DSM-5), more inclusive (≥2 NOMES), and most inclusive (≥1 NOMES) definitions. RESULTS: Among 153 depressed BD, compared to less inclusive DSM-5 threshold, our more and most inclusive thresholds, yielded approximately two- and five-fold higher mixed depression rates (7.2%, 15.0%, and 34.6% respectively), and important statistically significant clinical correlates for mixed compared to pure depression (e.g. more lifetime anxiety disorder comorbidity, more current irritability), which were not significant using the DSM-5 threshold. CONCLUSION: Further studies assessing strengths and limitations of more inclusive mixed depression definitions are warranted, including assessing the extent to which enhanced statistical power vs. other factors contributes to more vs. less inclusive mixed bipolar depression thresholds having more statistically significant clinical correlates, and whether 'overlapping' mood elevation symptoms should be counted.

Analysis of quantitative trait loci for main plant traits in soybean.

Plant traits are important indices for regulating and controlling yield ability in soybean varieties. It is important to comprehensively study the quantitative trait locus (QTL) mapping for soybean plant traits, cloning related genes, and marker assistant breeding. In this study, 236 F2 generation plants and a derivative group were constructed by using Jiyu50 and Jinong18, obtained from Jilin Province. A total of 102 simple sequence repeat markers were used to construct a genetic linkage map. With 2 years of molecular and phenotypic data, QTL analyses and mapping were conducted for soybean maturity, plant height, main stem node, main stem branch, seed weight per plant, and more. Five main plant traits were analyzed via inclusive composite interval mapping using QTL IciMapping v2.2. Using one-dimensional scanning, a total of 30 QTLs were detected and distributed across 1 (A1), 4 (C2), and 12 (G). There were 9 linkage groups, including 16 major QTLs. Using two-dimensional scanning, 7 pairs of epistatic QTL interactions for maturity and plant height were detected in the soybean.

Expression of high-mobility group box protein 1 in diabetic foot atherogenesis.

The role of high mobility group box 1 (HMGB1) has been demonstrated in stroke and coronary artery disease but not in peripheral arterial occlusive disease (PAOD). The pathogenesis of HMGB1 in acute and chronic vascular injury is also not well understood. We hypothesized that HMGB1 induces inflammatory markers in diabetic PAOD patients. We studied 36 diabetic patients, including 29 patients with PAOD, who had undergone amputation for diabetic foot and 7 nondiabetic patients who had undergone amputation after traumatic injury. Expression of HMGB1 and inflammatory markers were quantified using immunohistochemical staining. Mitochondrial DNA copy number was quantified using real-time polymerase chain reaction. Compared with that in the traumatic amputation group, HMGB1 expression in vessels was significantly higher in the diabetes and diabetic PAOD groups. In all subjects, arterial stenosis grade was positively correlated with the expression levels of HMGB1, 8-hydroxyguanosine, malondialdehyde, vascular cell adhesion molecule 1, and inflammatory markers CD3, and CD68 in both the intima and the media of vessels. Furthermore, HMGB1 expression level was positively correlated with 8-hydroxyguanosine, vascular cell adhesion molecule 1, nuclear factor-kB, CD3, and CD68 expression. Within the PAOD subgroup, subjects with HMGB1 expression had higher expression of the autophagy marker LC3A/B and higher mitochondrial DNA copy number. HMGB1 may be an inflammatory mediator with roles in oxidative damage and proinflammatory and inflammatory processes in diabetic atherogenesis. Moreover, it may have dual effects by compensating for increased mitochondrial DNA copy number and increased autophagy marker expression.

Identification of genes associated with the increased number of four-seed pods in soybean (Glycine max L.) using transcriptome analysis.

Seed number per pod is an important component of yield traits in soybean (Glycine max L.). In 2010, we identified a natural mutant with an increased number of four-seed pods from a soybean variety named 'Jinong 18' (JN18). Subsequent observations indicated that the trait was stably inherited. To identify and understand the function of genes associated with this mutant trait, we analyzed the genetic differences between the mutant (JN18MT01) and source variety (JN18) by transcriptome sequencing. Three types of tissues, axillary buds, unfertilized ovaries, and young pods at three different growth stages, V6, R1, and R3, were analyzed, respectively. The sequencing results yielded 55,582 expressed genes and 4183 differentially expressed genes (DEGs). Among these, the log2 ratio value of 162 DEGs was >10, and 13 DEGs had overlapping expression at three different growth stages. Comparisons of DEGs among three different growth stages yielded similar results in terms of the percentage of genes classified into each gene ontology (GO) category. DEGs were classified into 25 different functional groups in clusters of orthologous groups analysis. Proportions of the main functional genes differed significantly over developmental stages. A comparison of enriched pathways among the three developmental stages revealed that 646 unigenes were involved in 103 metabolic pathways. These results show that the development of four-seed pods is associated with a complex network involving multiple physiological and metabolic pathways. This study lays the foundation for further research on cloning and on the molecular regulation of genes related to the four-seed pod mutation.

Cloning of flanking sequence in transgenic plants by restriction site-anchored single-primer polymerase chain reaction.

Determining the insertion position of an exogenous gene in the target plant genome is one of the main issues in the transgenic plant field. This study introduced a simple, rapid, and accurate method to clone the flanking sequences of the transgenic bar gene as the anchoring gene in the transgenic maize genome using single-primer polymerase chain reaction (PCR). This method was based on the distribution of restriction sites in the maize genome and adopted the single-primer PCR method. Cloning the flanking sequences with the restriction site-anchored single-primer PCR simplified the experimental procedures by about 70% and reduced the experimental time by more than 80%. In conclusion, the restriction site-anchored single-primer PCR was a simple, rapid method to obtain the unknown flanking sequences in the transgenic plants.

Cloning flanking sequence by single-primer PCR in transgenic plants.

The insertion position of exogenous genes in plant genomes is usually identified by adapter ligation-mediated polymerase chain reaction (PCR), thermal asymmetric interlaced PCR, and restriction site extension PCR in transgenic plant research. However, these methods have various limitations, such as the complexity of designing primers and time-consuming and multiple-step procedures. The goal of this study was to establish an easier, more rapid, and more accurate method to clone flanking sequence using single-primer PCR in transgenic plants. Unknown flanking genome sequences in transgenic plants, including those in tobacco, soybean, rice, and maize, were cloned using the single-primer PCR method established in this study, with the Bar gene as the anchor gene. The primer 1 (P1), P2, and P3 PCRs obtained 4 sequences, and the completely correct flanking sequence of 508 bp that was obtained in the P3 PCR was verified by sequencing analysis. The single-primer PCR is more rapid and accurate than conventional methods, justifying its application widely in cloning flanking sequences in transgenic plants.

Genetic analysis of the major gene plus polygene model in soybean resistance to Leguminivora glycinivorella.

In order to investigate the genetic characteristics of soybean Leguminivora glycinivorella resistance and to improve soybean resistance insectivorous breeding efficiency by applying the multi-generation joint analysis method of the major gene plus polygene model, 5 pedigrees and generations (P1, F1, P2, F2, and F2:3) were used as the materials to perform the soybean L. glycinivorella resistance multi-generation joint analysis. The results showed that soybean resistance to L. glycinivorella was controlled and inherited by an additive major gene plus additive, dominant polygene. The major gene had a negative additive effect (d = -0.1633). The combination of the anti-L. glycinivorella genes showed negative heterosis. Because the polygene additive effects were positive, the polygene effects would increase the insect herbivory rate in the F1 generation. This hybrid combination showed an insect herbivory rate polygenic heritability of 21.9556 and 54.3490% in the F2 and F2:3 pedigrees, which presented a high heritability. Therefore, it was appropriate to perform the selective breeding of the insect herbivory rate in the late generation.

Role of mitochondrial DNA variants and copy number in diabetic atherogenesis.

Hyperglycemia-induced reactive oxygen species production can cause diabetes and its complications, including atherosclerosis. The role of mitochondrial DNA variants and mitochondrial copy number in the pathogenesis of diabetic atherogenesis is not well understood. We examined 36 diabetic patients who had undergone amputation for diabetic foot and seven non-diabetic patients who had undergone amputation after traumatic injury. Mitochondrial DNA was extracted and used for sequencing. Single nucleotide polymorphisms (SNPs) relative to the Cambridge reference sequence were analyzed. Mitochondrial DNA copy number was quantified by real-time PCR. Twenty-one novel variants were detected in 29 diabetic patients with arterial stenosis; six of the variants were heteroplasmic, and most occurred in highly evolutionarily conserved residues. These variants were more prevalent in patients with arterial stenosis than in those without stenosis. The novel variants included four in complex I (ND1: C3477A/C, A3523A/G; ND5: C13028A/C, C13060A/C), one in complex IV (COX1: T6090A/T), and one in rRNA (12srRNA: G857G/T). Compared with non-diabetic patients, the diabetic patients had significantly less mitochondrial DNA. Furthermore, among diabetic patients with arterial stenosis, there was a significant positive correlation between mitochondrial DNA copy number and the number of total SNPs. In conclusion, we identified six novel heteroplasmic mitochondrial DNA variants among diabetic patients with arterial stenosis, and we found that diabetic atherogenesis is associated with decreased amounts of mitochondrial DNA.

Single- and double-SSR primer combined analyses in rice.

Polymerase chain reaction (PCR) is the foundation of SSR molecular marker technology. We used sib rice varieties J518, XD1 and SD23 as experimental materials, selecting 30 pairs of SSR primers, including RM127, RM337 and RM5172, covering the rice genome, and performed single- and double-SSR primer combined analyses. We found that under the same PCR system and conditions, a single primer of the SSR primer pairs could amplify the same fragments as double primers do. The sequencing results demonstrated that some amplified fragments that we previously believed to come from double primers were actually produced by a single primer. The use of this kind of primer, such as the RM127 primer pair, for marker-assisted breeding will therefore be misleading. Additionally, using the same PCR system and conditions, some single primers that are part of SSR primer pairs can amplify many more specific fragments than double-SSR primers. For instance, in the case of the RM5172 primer pair, a single primer P1 amplified approximately three times the number of fragments as the double primer. This information can contribute to research on genetic diversity of species, understanding of genetic relationships and identification of germplasm resources. Accordingly, combined analyses of single- and double-primer amplification products not only can remove single-primer amplification fragments and false-positives from double-primer amplification products in order to improve test accuracy, but also can facilitate research on genetic diversity, exploration of phylogenetic relationships and identification of germplasm resources. We define this method as "single- and double-SSR primer combined analyses".

Problems with and a system to eliminate single-primer PCR product contamination in simple sequence repeat molecular marker-assisted selection in soybean.

Polymerase chain reaction (PCR) provides a foundation for simple sequence repeat molecular marker-assisted selection (SSR MAS) in soybean. This PCR system and its various conditions have been optimized by many researchers. However, current research on the optimization of the PCR system focuses on double-primer PCR products. We compared single- and double-SSR primer PCR products from 50 soybean samples and found that the use of single-PCR primers in the reaction system can lead to amplified fragments of portions of the SSR primers in the PCR process, resulting in both false-positives and fragment impurity of double-primer PCR amplification, inconvenient for subsequent analysis. We used "single-primer PCR correction" to eliminate interference caused by single-primer nonspecific PCR amplification and improve PCR quality. Using this method, the precision and success rates of SSR MAS in soybean can be increased.

Single-primer PCR correction: a strategy for false-positive exclusion.

Polymerase chain reaction (PCR) technology plays an important role in molecular biology research, but false-positive and nonspecific PCR amplification have plagued many researchers. Currently, research on the optimization of the PCR system focuses on double-primer-based PCR products. This research has shown that PCR amplification based on single-primer binding to the DNA template is an important contributing factor to obtaining false-positive results, fragment impurity, and nonspecific fragment amplification, when the PCR conditions are highly restricted during PCR-based target gene cloning, detection of transgenic plants, simple-sequence repeat marker-assisted selection, and mRNA differential display. Here, we compared single- and double-primer amplification and proposed "single-primer PCR correction"; improvements in PCR that eliminate interference caused by single-primer-based nonspecific PCR amplification were demonstrated and the precision and success rates of experiments were increased. Although for some kinds of experiments, the improvement effect of single-primer PCR correction was variable, the precision and success rate could be elevated at 12-50% in our experiment by this way.

Treatments for bipolar disorder: can number needed to treat/harm help inform clinical decisions?

OBJECTIVE: To compare bipolar treatment interventions, using number needed to treat (NNT) and number needed to harm (NNH). METHOD: Results of randomized controlled clinical trials were used to assess efficacy (NNT for response and relapse/recurrence prevention vs. placebo) and tolerability (e.g. NNH for weight gain and sedation vs. placebo). RESULTS: United States Food and Drug Administration-approved bipolar disorder pharmacotherapies all have single-digit NNTs (i.e. > 10% advantage over placebo), but NNHs for adverse effects that vary widely. Some highly efficacious agents are as likely to yield adverse effects as therapeutic benefit, but may be interventions of choice in more acute severe illness. In contrast, some less efficacious agents with better tolerability may be interventions of choice in more chronic mild-moderate illness. CONCLUSION: Clinical trials can help inform clinical decision making by quantifying the likelihood of benefit vs. harm. Integrating such data with individual patient circumstances, values, and preferences can help optimize treatment choices.

Association between a common mitochondrial DNA D-loop polycytosine variant and alteration of mitochondrial copy number in human peripheral blood cells.

BACKGROUND: A T-to-C transition at mitochondrial DNA (mtDNA) nucleotide position 16189 can generate a variable length polycytosine tract (poly-C). This tract variance has been associated with disease. A suggested pathogenesis is that it interferes with the replication process of mtDNA, which in turn decreases the mtDNA copy number and generates disease. METHODS: In this study, 837 healthy adults' blood samples were collected and determined for their mtDNA D-loop sequence. The mtDNA copy number in the leucocytes and serum levels of oxidative thiobarbituric acid reactive substance (TBARS) and antioxidative thiols were measured. All subjects were then categorised into three groups: wild type or variant mtDNA with presence of an interrupted/uninterrupted poly-C at 16180-16195 segment. RESULTS: A step-wise multiple linear regression analysis identified factors affecting expression of mtDNA copy number including TBARS, thiols, age, body mass index and the mtDNA poly-C variant. Subjects harbouring a variant uninterrupted poly-C showed lowest mean (SD) mtDNA copy number (330 (178)), whereas an increased copy number was noted in subjects harbouring variant, interrupted poly-C (420 (273)) in comparison with wild type (358 (215)). The difference between the three groups and between the uninterrupted poly-C and the composite data from the interrupted poly-C and wild type remained consistent after adjustment for TBARS, thiols, age and body mass index (p=0.001 and p=0.011, respectively). A trend for decreased mtDNA copy number in association with increased number of continuous cytosine within the 16180-16195 segment was noted (p(trend)<0.006). CONCLUSIONS: Our results substantiate a previous suggestion that the mtDNA 16189 variant can cause alteration of mtDNA copy number in human blood cells.