MXene Nanosheets-Decorated Paper as a Green Electronics Material for Biosensing.

This research delves into the development and optimization of MXene nanosheet-based paper electrodes, emphasizing their adaptability in green electronics and diverse applications. Xuan paper, a cellulose-based material, was identified as an ideal substrate for its mechanical attributes and capacity to accommodate MXene, further yielding outstanding electrical conductivity. The MXene paper electrode demonstrated consistent performance under various conditions, showing its potential in the field of wearable electronics and medical devices. Notably, its impressive electrothermal capabilities and environmentally conscious decomposition mechanism make it a promising candidate for future green electronic applications. Overall, this study underscores the electrode's harmonization of performance and environmental sustainability, paving the way for its integration into futuristic electronic solutions.

Formation history of Dao-di herbs in Dabie Mountains / 中国中药杂志

Dabie Mountains, a unique transition area of subtropical and warm temperate zone, span Anhui, Hubei and Henan pro-vinces with a humid and suitable climate. It is rich in traditional Chinese medicine resources including many Dao-di herbs, and has a profound culture of traditional Chinese medicine with many herbalists in the past. This paper combed the historical geography of Dabie Mountains and development vein of medicinal materials recorded in history, and a textual research on the historical evolution of Dao-di herbs and special herbs in Dabie Mountains was carried out. The administrative region of Dabie Mountains has been changing constantly in history, which includes 25 counties and districts of six cities in Anhui, Henan and Hubei provinces at present. Dabie Mountains abound in a variety of Chinese herbal medicines, which have been recorded in herbal works in the past dynasties and local chronicles in detail. The recorded Dao-di herbs Dendrobium huoshanense, Artemisia argyi, and Poria cocos are well-known in China, and the output of Gastrodia elata, Ganoderma lucidum, and P. cocos is in the forefront of the country. Additionally, there are still many local special herbs emerging in modern times. In a word, this paper reviewed development of historical geography and ancient records of medicinal materials in Dabie Mountains, and made a textual research on the Dao-di herbs and special herbs, will provide a reference for the mo-dern research and intellectual property protection of Dao-di herbs in Dabie Mountains.

Textual Research on Illustrations of Medicinal Materials Named After Geographical Names of Jiangsu Province in Illustrated Classic of Materia Medica / 中国实验方剂学杂志

Illustrated Classic of Materia Medica （Ben Cao Tu Jing）， compiled in 1061， is regarded as the crystallization of the second national survey of Chinese medicinal resources in the history of China after the Newly Revised Materia Medica （Xin Xiu Ben Cao）， which serves as a precious source for exploring the Chinese medicinal resources in the Song Dynasty. The Illustrated Classic of Materia Medica （Ben Cao Tu Jing） covers 50 illustrations for Chinese medicinal materials named after geographical names of Jiangsu Province， 39 of which have been verified in today's Jiangsu Province. To be specific， Chinese medicinal materials in 32 illustrations can be traced back to their species， those in four illustrations to genera， and those in three illustrations to family. The remaining 12 illustrations remain to be further verified. The origins of most Chinese medicinal materials in the illustrations can be traced， which is attributed to their exquisiteness and lifelikeness as well as the detailed descriptions of the characters of the original plants and animals. In the textual research of these illustrations， we have noticed that there are inconsistencies between pictures and texts， and different illustrations may be derived from the same origin. This is believed to be related to SU Song's principle of collation that "for all Chinese medicinal materials presented as examples， if their shapes and categories recorded are not consistent with those in the literature， they will be retained. If there is any connection with the literature， they will be annotated according to literature to make their origins clear". As revealed by the distribution of Chinese medical materials in Jiangsu Province reported in the Illustrated Classic of Materia Medica （Ben Cao Tu Jing）， the utilization and development of Jiangsu medicinal materials during the Northern Song Dynasty were mainly concentrated in the low-altitude valleys and coastal areas. It could be seen from the illustrations of Chinese medicinal materials named after geographical names of today's Jiangsu Province that the production areas with a large number of illustrations were relatively developed in politics， economy， and transportation at that time， which enabled the medicinal resources to be fully utilized.

The efficacy of repetitive transcranial magnetic stimulation for Parkinson disease patients with depression.

Objective: To evaluate the efficacy of repetitive transcranial magnetic stimulation for Parkinson disease (PD) patients with depression.Methods: A meta-analysis was performed using relevant randomized controlled trials (RCTs) from online databases such as PubMed, Embase, Cochrane Online Library, and Clinicaltrials.gov. Studies were selected according to pre-defined inclusion and exclusion criteria, and the quality of the studies was evaluated using the Jadad Scale. All data were pooled by RevMan 5.2 software for meta-analysis.Results: The review covered 528 articles, and 7 articles with Jadad score ≥4 were included in the analysis. The meta-analysis showed that, compared to sham repetitive transcranial magnetic stimulation (sham-rTMS), repetitive transcranial magnetic stimulation (rTMS) over dorsolateral prefrontal cortex (DLPFC) improved depression, but that there was no significant difference in depression improvement between rTMS and selective serotonin reuptake inhibitor (SSRI) treatment. In contrast, rTMS over DLPFC did not improve motor function compared to sham-rTMS or SSRI, and the studies that included neurocognitive measures showed no significant difference between rTMS and sham-rTMS.Conclusion: This meta-analysis provides evidence that rTMS over DLPFC can improve depression similar to SSRI treatment, has no effect on the motor function and cognition of PD patients with depression.

Anticancer effect of Psidium guajava (Guava) leaf extracts against colorectal cancer through inhibition of angiogenesis

Objective: To evaluate the anti-angiogenic and anticancer activities of Psidium guajava leaf extracts against angiogenesis-dependent colorectal cancer. Methods: Three extracts were produced using distilled water, ethanol, and n-hexane as solvents. The extracts were physically characterised through gas chromatography-mass spectrometry, ultraviolet-visible spectroscopy, and Fourier transform infrared spectroscopy. Their antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl, total phenolic content, and total flavonoid content assays. To assess their anti-angiogenic activity, cell viability and rat aortic ring assays were conducted, while cell migration, tube formation, colony formation, and VEGF ELISA assays were conducted to elucidate their effects on different aspects of angiogenesis. Molecular docking was used to assess the anti-angiogenic potential of some possible compounds in the extracts. Tumour spheroid assay was used to assess the extracts' potential as a treatment for colorectal cancer. Results: The ethanol extract showed the best antioxidant activity. The distilled water and ethanol extracts exhibited more inhibitory activity against EA.hy926 cell viability and aortic ring microvessel growth. In addition, the ethanol extract performed significantly better than the distilled water extract against cell migration and colony formation, and VEGF expression of the cells was suppressed by the ethanol extract. Both the distilled water and ethanol extracts showed significant inhibitory effect on EA.hy926 tube formation and tumour spheroids consisting of EA.hy926 and HCT116 cells. The ethanol extract contained β-caryophyllene and β-elemene by phytochemical analysis and subsequent docking studies, which may contribute to its anti-angiogenic activity. Conclusions: The ethanol extract of Psidium guajava has potential in the treatment of colorectal cancer through the inhibition of angiogenesis.

Linguistic Characteristics of Mandarin-Speaking Huntington's Disease Patients / 中国医学科学杂志(英文版)

Objective Linguistic problem is common in Huntington's disease (HD) patients. It has been studied before in native speakers of alphabetic languages, such as English. As a hieroglyphic language, Chinese differs from alphabetic languages in terms of phonology, morphology, semantics and syntax. We aimed to investigate the linguistic characteristics of manifest HD in native speakers of Mandarin. Meanwhile, we expected to explore the linguistic differences associated with cortical or subcortical pathology.Methods Five HD patients and five Alzheimer's disease (AD) patients matched in age, gender, disease course and educational level were enrolled. All the participants were Mandarin native speakers. All finished history inquiry, physical examination, basic test, genetic test and neuropsychological assessment. Language evaluation was performed by Aphasia Battery of Chinese.Results HD patients had a mean disease course of 5.4±2.97 (range, 2-10) years. They showed a linguistic disorder close to transcortical motor aphasia. They exhibited prominent phonological impairment, as well as slight semantic and syntactic abnormality. Tonic errors were found in speech. Character structural errors and substitutions were detected in writing. In comparison, AD patients showed a more severe linguistic impairment, characterized by global aphasia with more semantic errors. Conclusion Mandarin-speaking HD patients have a transcortical motor aphasia-like disturbance with prominent phonological impairment, whereas AD patients have a more severe global aphasia with salient semantic impairment.

Characterization and antioxidant activity of pectin from Indonesian mangosteen (Garcinia mangostana L.) rind.

Pectin, a natural polysaccharide, has gained increasing attention due to not only its biomaterial properties but also its biomedical activities. One of the abundant sources of pectin is mangosteen (Garcinia mangostana L.) rind. In this study, we characterized the pectin from Indonesian mangosteen rind extract and evaluated its antioxidant activity. Pectin was extracted in acid condition and evaluated its physicochemical properties by fourier transform infrared (FTIR), powder X-ray diffractometer (PXRD), water content, ash content, equivalent weight, methoxyl level and of galacturonic acid content. Furthermore, the antioxidant activity of pectin was also observed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Pectin was successfully extracted from dry weight of Indonesian mangosten rind with yield about 1,16 ± 0,17%, fine powder, brownish and odorless. FTIR and PXRD results showed that pectin from mangosteen rind extract was amorphous and similar characteristic with a commercial pectin. The chemical properties of pectin such as water content, ash content, equivalent weight, methoxyl level and of galacturonic acid level were 9.85 ± 0.12%, 3.91 ± 0.17%, 6330.76 ± 220.43 g/mol, 2.86 ± 0.05% and 75.98 ± 0.88%, respectively. In addition, pectin showed an antioxidant activity with the IC50 about 161.94 ± 31.57 ppm. These results suggest that pectin from Indonesian mangosteen rind has the potential properties as biopolymers for biomedical applications with a low-methylated pectin and a moderate antioxidant activity.

Identification of Corydalis yanhusuo,C. turtschaninovii,C. decumbens by allele-specific PCR / 中国中药杂志

To establish a DNA molecular markers method for identification of Corydalis yanhusuo,C. turtschaninovii and C. decumbens,the mat K,trn G and psb A-trn H sequences of 56 samples from 14 species of C. yanhusuo,C. turtschaninovii,C. decumbens and their related species were obtained by sequencing. The SNP loci were obtained by Bio Edit 7. 2. 2 software. The primers for AS-PCR identification were designed based on the mutation sites,and the conditions of PCR were optimized to identify C. yanhusuo,C. turtschaninovii,and C. decumbens according to the specific bands. The results showed that the amount of template( 0. 6-1 200 ng)and annealing temperature( 42-60 ℃) had little influence on the amplification results,and the number of cycles had much influence on the amplification results. When the number of cycles was 20,the specific bands of 297 bp( mat K),353 bp( trn G) and 544 bp( mat K) were amplified from C. yanhusuo,C. turtschaninovii and C. decumbens,respectively. The method established in this study had a minimum detection limit of 6 ng for C. yanhusuo,60 ng for C. decumbens and less than 0. 6 ng for C. turtschaninovii. Thus,the allelespecific PCR method established in the research can specifically identify C. yanhusuo,C. turtschaninovii,and C. decumbens.

Preparation and bioIogicaI properties of TiN/Ag composite coating on pure titanium surface / 中国组织工程研究

BACKGROUND: It is of vital importance to fabricate an interface on the titanium implant surface which can promote early cell adhesion, proliferation, and differentiation, and exert better antibacterial effects with no cytotoxicity. OBJECTIVE: To prepare a TiN/Ag composite coating on the surface of pure titanium implant, and to explore its antibacterial properties and effects on MC3T3-E1 biobehaviors. METHODS: Acid etching blasting and multi-arc ion plating were adopted to prepare TiN/Ag composite coating on the smooth surface of pure titanium. Then, MC3T3-E1 cells that grew well were inoculated onto pure titanium plate, sandblasted and acid-etched titanium plate, and TiN/Ag-coated titanium plate. Twenty-four hours later, cell adhesion and viability were observed under confocal laser scanning microscope, and cell morphology was observed under scanning electron microscope. Cell counting kit-8 was used to detect cell proliferation and cytotoxicity at 24,48,72 hours after inoculation.In addition,Staphylococus aureus solution was dropped onto the smooth titanium plated, acid-etched and sandblasted titanium and TiN/Ag-coated titanium plate, and the growth of bacteria was observed by the laser confocal scanning microscope at 16 hours. RESULTS AND CONCLUSION: Under the confocal laser scanning microscope, spindle cells with bipolar or three poles were observed on the smooth titanium surface, and there was less F-actin and filopodia expression; cells on the TiN/Ag-coated titanium surface and sandblasted and acid-etched titanium surface were scattered with a large amount of interconnected filopodia that were fully stretched and adhered to the titanium surface, highly expressed F-actin was detected, and actin fibers were thickened. Under the scanning electron microscope, the cells on the smooth titanium surface were not fully adhered and stretched, and those on the TiN/Ag-coated titanium surface or the sandblasted and acid-etched titanium surface exhibited better adhesion and extension. Findings from the cell counting kit-8 showed that after 72 hours of inoculation,the cells on the smooth titanium surface grew well,with cytotoxicity level 1.In addition,Staphylococus aureus grew well on the smooth titanium surface under the confocal laser scanning microscope,while a large amount of Staphylococus aureus died on the TiN/Ag-coated titanium surface or on the sandblasted and acid-etched titanium surface. These findings indicated that TiN/Ag coating has good biocompatibility and antibacterial properties.

Growth rings in roots of seven Sect. Paeonia species and its application on identification of Paeoniae Radix Rubra / 中国中药杂志

The growth years of medicinal materials are closely related to their quality, and "Herb-chronology" has been used to determine the growth years of perennial dicotyledonous plants in recent years. On the basis of conventional paraffin section and freehand section, the anatomical study on roots of seven Sect. Paeonia species and main roots of cultivated Paeonia lactiflora was conducted in this paper. The results showed that, there existed some differences in microstructure of the seven species such as P. lactiflora, P. obovata, P. veitchii, P. mairei, P. anomala, P. sinjiangensis and P. anomala var. intermedia, and this could be used to distinguish different species. In the roots of seven Sect. Paeonia species, distinct growth rings were formed because that the different diameters or density of xylem vessels in the secondary xylem formed clusters and arranged interrupted rings in tangential direction. There were growth rings in the main roots of P. lactiflora cultivated 1-4 years in Siping, Jilin, which were all consistent with their growth years. Due to the similar growth characteristics between wild Sect. Paeonia species and cultivated P. lactiflora, the growth rings can provide a basis for the age identification and lay the foundation for the quality evaluation of Paeoniae Radix Rubra.

Stress among First and Third Year Medical Students at University Kebangsaan Malaysia.

OBJECTIVE: To identify the stress-prevalence and coping-strategies among University Kebangsaan Malaysia (UKM) medical students. METHODS: This was an observational study conducted among 234 UKM first and third year medical students. Standardized questionnaire on stress and coping strategies was used. Stress data was related to subjective experiences on some positive and negative adjectives such as tense, relaxed etc. Positive adjectives were measured by sign "++" and "+" scoring "1" while stress-negative adjectives were measured by sign "?" and "-" scoring "0". Forty-eight coping items under task, emotion and avoidance strategies were measured using 5-point Likert-scale. RESULTS: Overall stress-prevalence was 49%. Female and Malay respondents were more stressed. Significant differences of stress-level was observed between Malays and non Malays in first year (p=0.04) and in third year (p=0.01). Most common strategies used to cope stress was task-oriented while emotion oriented was least. CONCLUSION: Stress-prevalence and stress-level in UKM medical students was high. Most of the respondents coped stress using task-oriented strategies. Stressor and its effective management must be ensured. Educational institutions should act as a creative designer of learning environment to get relieve from educational stressor.

Distribution laws of 5 compounds in rhizome and root of Polygonum cuspidate / 中国中药杂志

To understand the distribution and accumulation rules of polydatin, resveratrol, anthraglycoside B, emodin and physicion in different tissue structure of rhizome and root of Polygonum cospidatum, the content of 5 active compounds were analyzed simultaneously by HPLC, based on plant anatomy and histochemistry. The rhizome and root consist of different tissues, with an increased diameter, the proportions of the secondary xylem and phloem have increased. Resveratrol and polydatin mainly distributed in the pith, the secondary phloem and periderm of rhizome, and the secondary phloem and periderm of the root, while emodin and anthraglycoside B concentrated in the secondary structure and pith of rhizome mostly. In different thickness of the measured samples, the total contents of 5 compounds were correspondingly higher in thinner rhizome and root than those in the coarse ones.

Selected pharmaceutical excipient prevent isoniazid and rifampicin induced hepatotoxicity.

BACKGROUND & AIMS: The incidence of isoniazid (INH)- and rifampicin (RIF)-induced abnormal liver enzyme activity is 27% but only 19% with INH alone. Cytochrome P450 2E1 (CYP2E1) is thought to contribute to the synergistic effects of RIF and INH. Pharmaceutical excipients are inactive ingredients that are added to a pharmaceutical compound. The purpose of this study was to screen excipients for CYP2E1 inhibition and identify whether the screened excipients prevented INH/RIF-induced hepatotoxicity. METHODS: Fifty-five known pharmaceutical excipients were screened for CYP2E1 inhibition. The hepatotoxic doses of INH and RIF were 50 and 100 mg/kg/day, respectively. Hepatotoxicity was assessed by the galactose single point (GSP) method (a US Food and Drug Administration (FDA) recommended quantitative liver function test), liver histopathology, malondialdehyde (MDA) assay, and measurement of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity. We chose the CYP2E1-specific substrate chlorzoxazone to assess CYP2E1 activity in animal and human. RESULTS: Mannitol inhibited CYP2E1 activity by 54% in mice with INH/RIF-induced hepatotoxicity (p < 0.005). Serum AST, ALT and GSP levels were significantly increased 3.8- to 7.8-fold in these mice (p < 0.005), and these levels could be lowered by mannitol. Mannitol significantly alleviated the depletion of hepatic glutathione (GSH) and partially reversed the increase in MDA formation in mice treated with INH/RIF (p < 0.005). Mannitol also decreased CYP2E1 activity by 58% in humans (p < 0.005). Furthermore, an antituberculosis (TB) efficacy assay revealed that mannitol did not affect the anti-TB effects of INH/RIF. CONCLUSIONS: Mannitol, an FDA-approved excipient, was found to be a CYP2E1 inhibitor. Mannitol may be a useful adjuvant for drugs that induce hepatotoxicity through CYP2E1, such as INH and RIF.

Comparative kinetics of thiol oxidation in two distinct free-radical generating systems: SIN-1 versus AAPH.

To study oxidative stress in biological systems, chemical compounds capable of producing free radicals have been widely used. Here, we compared two free-radical generators, 3-morpholinosydnonimine (SIN-1) and 2,2'-azo-bis(2-amidinopropane) hydrochloride (AAPH), by measuring the thiol oxidation kinetics of various thiols. We found that SIN-1 is > 30 times potent in causing thiol oxidation than AAPH. Kinetic simulations revealed that in the SIN-1 system (0.1 mM), superoxide, nitrogen dioxide and carbonate radicals are the major reactive species which, in combination, induce ∼50% of thiol molecules to undergo one-electron oxidation, thereby forming the thiyl radical which propagates further thiol oxidation by direct coupling with thiolates. Similarly, the alkyl peroxyl radical derived from AAPH (3 mM) initiates comparable extent of one-electron oxidation and formation of the thiyl radical. In conclusion, our study provides experimental and theoretical evidence that SIN-1 is mainly an one-electron oxidizing agent that can be functionally mimicked by AAPH.

Similarity and dissimilarity of thiols as anti-nitrosative agents in the nitric oxide-superoxide system.

Concomitant production of nitric oxide and superoxide in biological systems has been proposed to generate numerous reactive oxygen and nitrogen species that cause oxidative and nitrosative stress. Thiols, especially glutathione, play an important role in cellular defense against radical species. In the present study, we investigated and compared the anti-nitrosative activity of a wide range of thiols in a simplified chemical system of co-generated nitric oxide and superoxide. Of the 13 thiols studied, three groups of thiols are distinguishable: (i) Group I includes cysteine and its four congeners (cysteine methyl ester, cysteine ethyl ester, homocysteine, cysteamine); they are subject to rapid oxidative decomposition and have the least anti-nitrosative activity. (ii) Group II consists of glutathione, penicillamine, tiopronin and mesna; they have the greatest effect on delaying the nitrosation reaction. (iii) Group III comprises N-acetylcysteine, N-acetylpenicillamine, captopril, and thioglycolate; they all have high pK(a) for the mercapto group and show the strongest inhibitory effect on the rate and extent of nitrosation in the system studied.

Echocardiographic mapping of left ventricular resynchronization during cardiac resynchronization therapy procedures / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cardiac resynchronization therapy (CRT) is an effective electrical therapy for patients with moderate to severe heart failure and cardiac dyssynchrony. This study aimed to investigate the degree of acute left ventricular (LV) resynchronization with biventricular pacing (BVP) at different LV sites and to examine the feasibility of performing transthoracic echocardiography (TTE) to quantify acute LV resynchronization during CRT procedure.</p><p><b>METHODS</b>Fourteen patients with NYHA Class III-IV heart failure, LV ejection fraction < or = 35%, QRS duration > or = 120 ms and septal-lateral delay (SLD) > or = 60 ms on tissue Doppler imaging (TDI), underwent CRT implant. TDI was obtained from three apical views during BVP at each accessible LV site and SLD during BVP was derived. Synchronicity gain index (Sg) by SLD was defined as (1 + (SLD at baseline--SLD at BVP)/SLD at baseline).</p><p><b>RESULTS</b>Seventy-two sites were studied. Positive resynchronization (R+, Sg > 1) was found in 42 (58%) sites. R+ was more likely in posterior or lateral than anterior LV sites (66% vs. 36%, P < 0.001). Concordance of empirical LV lead implantation sites and sites with R+ was 50% (7/14).</p><p><b>CONCLUSIONS</b>The degree of acute LV resynchronization by BVP depends on LV lead location and empirical implantation of LV lead results in only 50% concordance with R+. Performing TTE during CRT implantation is feasible to identify LV sites with positive resynchronization.</p>

Calpain I inhibition prevents atrial structural remodeling in a canine model with atrial fibrillation / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Atrial fibrillation (AF) is accompanied by atrial structural remodeling. Calpain activity is induced during AF. To test a causal relationship between calpain activation and atrial structural changes, N-acetyl-Leu-Leu-Met (ALLM), a calpain inhibitor, was utilized in a canine AF model.</p><p><b>METHODS</b>Fifteen dogs were randomly divided into 3 groups: sham-operated group, control group and calpain inhibitor group; each with 5 dogs. Sustained AF was induced by rapid right atrium pacing at 600 beats per minute for 3 weeks. ALLM was administered at a dosage of 1.0 mg x kg(-1) x d(-1) in the calpain inhibitor group. Three weeks later, the proteolysis, protein expression of TnT and myosin, calpain I localization and expression and structural changes were examined in left atrial free walls, right atrial free walls and the interatrial septum respectively. Atrial size and contractile function were also measured by echocardiography.</p><p><b>RESULTS</b>Long-term rapid atrial pacing induced marked structural changes such as enlarged atrial volume, myolysis, degradation of TnT and myosin, accumulation of glycogen and changes in mitochondrial shape and size, which were paralleled by an increase in calpain activity. The positive correlation between calpain activity and the degree of myolysis (r(s) = 0.90 961, P < 0.0001) was demonstrated. In addition to structural abnormalities, pacing-induced atrial contractile dysfunction was observed in this study. The pacing-induced atrial structural alterations and loss of contractility were partially prevented by the calpain inhibitor ALLM.</p><p><b>CONCLUSIONS</b>Activation of calpain represents key features in the progression towards overt structural remodeling. Calpain inhibitor, ALLM, suppressed the increased calpain activity and reversed structural remodeling caused by sustained atrial fibrillation in the present model. Calpain inhibition may therefore provide a possibility for therapeutic intervention in AF.</p>

Calpain I inhibition prevents pacing-induced structural remodeling for atrial fibrillation in canine / 中华心血管病杂志

<p><b>OBJECTIVE</b>To study the relation of the structural remodeling processes and activation of calpain I.</p><p><b>METHODS</b>Fifteen dogs were randomly divided into three groups. The dogs in pacing group (n=5) and inhibitor group (n=5) were subjected to 3 weeks of rapid atrial pacing at 600 beats/min, control dogs (n=5) were in sham-operated group. The dogs in inhibitor group were administered intravenous N-Acetyl-Leu-Leu-Met (ALLM), a calpain inhibitor, and in pacing group and sham-operated group were administered intravenous DMSO. The activity of calpain I was measured by hydrolyzing Suc-Leu-Leu-Val-Tyr-7-amino-4-methyl-coumarin. The ultrastructure of atrium was examined by light and electron microscopy. TnT expression was assessed by Western blot. Echocardiography examination was performed in all the three groups.</p><p><b>RESULTS</b>Calpain I activity was significantly increased in pacing group (2.3-fold, P<0.01), and decreased in inhibitor group (1.1-fold, P>0.05), compared to sham-operated group respectively. The percentages of myolysis were (76.7 +/- 5.9)% and (20.8 +/- 8.1)% in pacing group and inhibitor group respectively (P<0.01). TnT expression decreased in the rapid pacing-induced persistent atrial fibrillation, and these effects were inhibited by calpain I inhibitor ALLM. The area and volume of left atrium tended to increase after 3 weeks ALLM treatment in inhibitor group, but the change was not as prominent as in pacing group (P<0.05).</p><p><b>CONCLUSIONS</b>ALLM can decrease calpain I activity, and prevent canine atrial cardiomyocyte structural remodeling during atrial fibrillation. This study provided a capacity of atrial cardiomyocyte protection.</p>