The optimal cut-off value of five-time chair stand test for assessing sarcopenia among Chinese community-dwelling older adults.

BACKGROUND: The five-time chair stand test (5CST) as an indicator of muscle strength and physical function is the first step in assessing sarcopenia. We aimed to determine the optimal cut-off value of the 5CST for assessing older adults with sarcopenia in the Chinese community. METHODS: We used a stratified cluster random sampling method to recruit older adults from Chinese communities. The handgrip strength was assessed using an electronic handgrip dynamometer. The 5CST and gait speed were assessed by the trained researchers. The bioimpedance analysis device was used to evaluate the skeletal muscle index. We used the Asian Working Group for Sarcopenia diagnosis criteria as the gold standard. According to the receiver operating characteristic curve, we determine the optimal cut-off value using the Youden index. RESULTS: A total of 1027 participants were included in this analysis, including 337 men and 690 women with an average age of 70.35 ± 7.24 years. The prevalence of sarcopenia in total participants was 24.9%. The optimal cut-off value of 5CST in the total population was 10.9 s. Stratified by age and gender, for the older adults aged 60-69 years, the optimal cut-off values were 9.2 s in men and 10.8 s in women; for the older adults aged 70-79 years, cut-off values were 10.2 s in men and 10.9 s in women; and for the older adults over 80 years, cut-off values were 14.0 s in men and 11.5 s in women (all P < 0.001). The areas under the curve of 5CST were 0.632 in men and 0.650 in women (both P < 0.001). Using the newly defined cut-off values, the prevalence of sarcopenia increased significantly (P < 0.001). CONCLUSIONS: We determined the optimal cut-off value of the 5CST for assessing older adults with sarcopenia in the Chinese community, and this cut-off can significantly improve the detection rate of sarcopenia. The cut-off determined in our study will help community workers detect more people with sarcopenia and benefit from early intervention and management of sarcopenia in practice.

Examination of the role of the rotating nursing department in the training of nursing staff based on SWOT analysis.

BACKGROUND: The implementation of the rotation system in the Chinese medical industry has achieved significant results. OBJECTIVES: The present study aims to 1) explore the strengths, weaknesses, opportunities and challenges of rotational nursing department implementation and 2) provide references for developing nursing staff's competencies in leadership, performance evaluation, quality of care, communication in relationships and human resources. METHODS: A total of 16 rotational nursing department staff members from a tertiary tuberculosis specialist hospital in Beijing were interviewed, and the interview data were analysed using a strengths, weaknesses, opportunities and threats analysis and class analysis. RESULTS: The advantages of the rotational nursing department included: (1) stimulating the nursing staff's enthusiasm and creativity; (2) strengthening the communication and collaboration between departments; (3) improving the detailed management of nursing quality; and (4) enhancing the nursing staff's comprehensive abilities. The disadvantages included: (1) the design of the rotation programme focusing on practice; (2) a lack of personalisation; and (3) imperfect performance assessment of the rotating staff. Opportunities included: (1) deepening the connotation of nursing job management and (2) developing the construction of nursing discipline and the need for personal career development and value realisation. Threats included the lack of a sound rotation management model to draw on. CONCLUSION: A rotational nursing department is conducive to enhancing the competence of nursing staff in management positions and providing new ideas for hospitals to select and train nursing management talents. By taking full advantage of the benefits of vertical nursing management, designing personalised rotation training programmes, building a diversified learning and training platform and developing a positive performance incentive mechanism is recommended to fully engage the role of rotation in nursing management talent training.

Multiple domestications of Asian rice.

The origin of domesticated Asian rice (Oryza sativa L.) has been controversial for more than half a century. The debates have focused on two leading hypotheses: a single domestication event in China or multiple domestication events in geographically separate areas. These two hypotheses differ in their predicted history of genes/alleles selected during domestication. Here we amassed a dataset of 1,578 resequenced genomes, including an expanded sample of wild rice from throughout its geographic range. We identified 993 selected genes that generated phylogenetic trees on which japonica and indica formed a monophyletic group, suggesting that the domestication alleles of these genes originated only once in either japonica or indica. Importantly, the domestication alleles of most selected genes (~80%) stemmed from wild rice in China, but the domestication alleles of a substantial minority of selected genes (~20%) originated from wild rice in South and Southeast Asia, demonstrating separate domestication events of Asian rice.

Survey and analysis of willingness to use mobile medical services and influencing factors of TB patients treated at home.

INTRODUCTION: The objective of this study was to investigate the willingness of patients with tuberculosis (TB) to use mobile medical services (mHealth) and its influencing factors, so as to provide theoretical guidance for optimizing the TB mobile medical platform and improve the willingness of patients to use mHealth. METHODOLOGY: In this cross-sectional study, convenience sampling method was used to investigate patients with TB from the outpatient clinics of two TB specialized hospitals (Beijing Thoracic Tumor and Tuberculosis Hospital and Tuberculosis Prevention and Treatment Hospital of Shaanxi Province) from January to June 2021 using a self-designed questionnaire. RESULTS: Out of 231 patients, only 90 (38.96%) were aware of mHealth services, and 63 (27.27%) had used mHealth services. Among the 63 patients who had used mHealth services, the proportion of mobile medical forms based on WeChat platform was 74.89%. Patients' willingness to use mHealth was scored (11.49 ± 2.53). Univariate analysis showed that the scores of patients' willingness to use mHealth differed by gender and the different ways of affording healthcare (p < 0.05). Regression analysis showed that the influencing factors of willingness to use mHealth in patients with TB included attitude towards use (0.750), health beliefs (0.091) and social impact (0.169) (adjusted R2 = 0.781, p < 0.001). CONCLUSIONS: Patients' awareness of the advantages of the new medical model needs to be improved. Optimized design can improve the willingness of patients to use mHealth services and improve the role of mHealth in patient management.

Prevalence and diagnostic agreement of sarcopenic obesity with different definitions among Chinese community-dwelling older adults.

OBJECTIVE: this retrospective study aims to compare the prevalence and diagnostic agreement of sarcopenic obesity (SO) using different obesity diagnostic methods among Chinese community-dwelling older adults. METHODS: SO was diagnosed with sarcopenia and obesity diagnostic methods. Sarcopenia was defined using the Asian Working Group for Sarcopenia criteria 2019 (AWGS2019). Four widely used indicators were used to define obesity: body mass index (BMI), waist circumference (WC), percent of body fat (PBF) and visceral fat area (VFA). Cohen's kappa was used to analyse the diagnosis agreement of SO between different diagnostic methods. RESULTS: a total of 1,050 participants were included, including 347 men (71.3 ± 7.4 years) and 703 women (69.9 ± 7.5 years). The prevalence of sarcopenia was 25% in total participants, there was no difference between men (24.2%) and women (25.5%), (P = 0.705). With different obesity diagnostic methods, the obesity prevalence ranged from 4.1 to 42.2%, the SO prevalence was 0.1-7.9%. The diagnosis agreement of SO was poor-to-moderate (κ ranged from -0.002 to 0.682). Among the four diagnostic methods, AWGS combined with BMI had the poorest agreement (κ = -0.002 with other methods), AWGS combined with VFA had the best agreement (κ = 0.641 and 0.682 with AWGS combined with PBF and with AWGS combined with WC, respectively). CONCLUSION: the prevalence of SO vary considerably and the diagnostic agreement is poor-to-moderate with non-uniform diagnostic methods. BMI has the lowest sensitivity, whereas VFA has the highest sensitivity in diagnosis of SO, and VFA has a relatively good diagnostic agreement with other diagnostic methods.

Development and Validation of a Nomogram for Predicting Sarcopenia in Community-Dwelling Older Adults.

OBJECTIVE: To establish and validate a nomogram that predicts the risk of sarcopenia for community-dwelling older residents. DESIGN: Retrospective study. SETTING AND PARTICIPANTS: A total of 1050 community-dwelling older adults. METHODS: Data from a survey of community-dwelling older residents (≥60 years old) in Hunan, China, from June to September 2019 were retrospectively analyzed. The survey included general demographic information, diet, and exercise habits. Sarcopenia diagnosis was according to 2019 Asian Working Group for Sarcopenia criteria. Participants were randomly divided into the development group and validation groups. Independent risk factors were screened by multivariate logistic regression analysis. Based on the independent risk factors, a nomogram model was developed to predict the risk of sarcopenia for community-dwelling older adults. Both in the development and validation sets, the discrimination, calibration, and clinical practicability of the nomogram were verified using receiver operating characteristic curve analysis, Hosmer-Lemeshow test, and decision curve analysis, respectively. RESULTS: Sarcopenia was identified in 263 (25.0%) participants. Age, body mass index, marital status, regular physical activity habit, uninterrupted sedentary time, and dietary diversity score were significant contributors to sarcopenia risk. A nomogram for predicting sarcopenia in community-dwelling older adults was developed using these factors. Receiver operating characteristic curve analysis showed that the area under the curve was 0.827 (95% CI 0.792-0.860) and 0.755 (95% CI 0.680-0.837) in the development and validation sets, respectively. The Hosmer-Lemeshow test yielded P values of .609 and .565, respectively, for the 2 sets. The nomogram demonstrated a high net benefit in the clinical decision curve in both sets. CONCLUSIONS AND IMPLICATIONS: This study developed and validated a risk prediction nomogram for sarcopenia among community-dwelling older adults. Sarcopenia risk was classified as low (<11%), moderate (11%-70%), and high (>70%). This nomogram provides an accurate visual tool to medical staff, caregivers, and older adults for prediction, early intervention, and graded management of sarcopenia.

Mitochondrial Quality Control in Sarcopenia: Updated Overview of Mechanisms and Interventions.

Sarcopenia is a common geriatric disorder characterized by decreased muscle strength, low muscle mass and poor physical performance. This aging-related skeletal muscle deterioration leads to adverse outcomes and severely impairs the quality of life of patients. The accumulation of dysfunctional mitochondria with aging is an important factor in the occurrence and progression of sarcopenia. Mitochondrial quality control (MQC) fundamentally ensures the normal mitochondrial functions and is comprised of four main parts: proteostasis, biogenesis, dynamics and autophagy. Therefore, any pathophysiologic factors compromising the quality control of homeostasis in the skeletal muscle may lead to sarcopenia. However, the specific theoretical aspects of these processes have not been fully elucidated. Current therapeutic interventions using nutritional and pharmaceutical treatments show a modest therapeutic efficacy; however, only physical exercise is recommended as the first-line therapy for sarcopenia, which can ameliorate skeletal muscle deficiency by maintaining the homeostatic MQC. In this review, we summarized the known mechanisms that contribute to the pathogenesis of sarcopenia by impairing normal mitochondrial functions and described potential interventions that mitigate sarcopenia through improving MQC.

Mouse models of sarcopenia: classification and evaluation.

Sarcopenia is a progressive and widespread skeletal muscle disease that is related to an increased possibility of adverse consequences such as falls, fractures, physical disabilities and death, and its risk increases with age. With the deepening of the understanding of sarcopenia, the disease has become a major clinical disease of the elderly and a key challenge of healthy ageing. However, the exact molecular mechanism of this disease is still unclear, and the selection of treatment strategies and the evaluation of its effect are not the same. Most importantly, the early symptoms of this disease are not obvious and are easy to ignore. In addition, the clinical manifestations of each patient are not exactly the same, which makes it difficult to effectively study the progression of sarcopenia. Therefore, it is necessary to develop and use animal models to understand the pathophysiology of sarcopenia and develop therapeutic strategies. This paper reviews the mouse models that can be used in the study of sarcopenia, including ageing models, genetically engineered models, hindlimb suspension models, chemical induction models, denervation models, and immobilization models; analyses their advantages and disadvantages and application scope; and finally summarizes the evaluation of sarcopenia in mouse models.

Comparison of Three Screening Methods for Sarcopenia in Community-Dwelling Older Persons.

OBJECTIVE: The 2019 Asian Working Group on Sarcopenia in Older People (AWGS 2019) recommends using either calf circumference or the strength, assistance in walking, rising from a chair, climbing stairs, and falls (SARC-F) or SARC-F combined with calf circumference (SARC-CalF) questionnaires for sarcopenia screening. The aim of this study was to compare the ability and applicability of calf circumference, SARC-F, and SARC-CalF for screening sarcopenia among community-dwelling older adults. DESIGN: Cross-sectional study. SETTING AND PARTICIPANTS: A total of 1050 community-dwelling older people were enrolled. METHODS: Sarcopenia was diagnosed according to the AWGS 2019 criteria: bioimpedance analysis for appendicular skeletal muscle index, hand grip, and 6-m gait speed test. Participants also completed the SARC-F questionnaire and calf circumference measurement. The screening tools' performances were evaluated through receiver operating characteristic (ROC) curves, area under the ROC curves (AUC), and sensitivity/specificity analyses. RESULTS: Sarcopenia was identified in 263 (25.0%) participants by the AWGS 2019 criteria. Calf circumference had a sensitivity of 81.4% and a specificity of 77.0%. Sensitivity and specificity of SARC-F for screening sarcopenia were 17.9% and 93.7%, respectively. SARC-CalF improved the sensitivity of SARC-F (47.5%) while keeping similar specificity (92.0%). The AUCs of calf circumference, SARC-F, and SARC-CalF were 0.79 [95% confidence interval (CI), 0.77-0.82], 0.56 (95% CI, 0.52-0.59), and 0.70 (95% CI, 0.67-0.73), respectively. The differences across ROC curves were statistically significant among 3 screening tools (P < .001). CONCLUSIONS AND IMPLICATIONS: The overall screening ability of calf circumference was better than that of SARC-F and SARC-CalF for sarcopenia in community-dwelling older persons despite gender, age, and cognitive function. SARC-F and SARC-CalF have high specificity but are susceptible to the preceding factors.

The complete chloroplast genome of Pertya phylicoides (Asteraceae, Pertyeae): a shurby endemic species from China.

This study was the first report about complete chloroplast genome of Pertya phylicoides (Asteraceae: Pertyeae), a critically shurby plant. The complete chloroplast genome of Pertya phylicoides was 153,379 bp in length and a typical circular structure, which comprises a pair of inverted repeat (IR) region of 25,191 bp divided by a large single-copy (LSC) region of 84,535 bp and a small single-copy (SSC) region of 18,462 bp. The general GC content was 37.6% in the whole sequence, whereas corresponding values of 35.6%, 31.2%, and 43.1% in the LSC, SSC, and IR regions, respectively. The whole genome contained 113 unique genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 tRNA genes. The phylogenetic hypotheses obtained based on the analyses of 21 cp genomes indicates Pertya phylicoides was supported as a sister group to the tribe Carduoideae.

Divergence in flowering time is a major component contributing to reproductive isolation between two wild rice species (Oryza rufipogon and O. nivara).

It is of critical importance for our understanding of speciation process to determine the forms of reproductive isolation and their relative importance in species divergence. Oryza nivara and O. rufipogon are direct ancestors of Asian cultivated rice and a progenitor-daughter species pair. Investigating the reproductive isolation between them provides insights into plant speciation and helps understanding of the rice domestication. Here, we quantitatively measured the major components of reproductive isolation between the two species based on common garden and crossing experiments for three pairs of sympatric populations in Nepal, Cambodia and Laos. We revealed significant differences in the flowering times between species pairs, with O. nivara flowering much earlier than O. rufipogon. A very weak reduction in seed set but no reduction in F1 viability and fertility were detected for the crosses between species relative to those within species. Moreover, we detected asymmetrical compatibility between species and found that emasculation significantly decreased pollination success in O. nivara but not in O. rufipogon. Our study demonstrates that the divergence between O. nivara and O. rufipogon is maintained almost entirely by the difference in flowering times and suggests that differential flowering times contribute to both habitat preferences and reproductive isolation between species.

The complete chloroplast genome of Aster hypoleucus (Asteraceae: Astereae): an endemic species from China.

This study was the first report about complete chloroplast genome of Aster hypoleucus (Asteraceae, Astereae), an endemic species in Xizang (China). The circular whole cp genome of A. hypoleucus was 152,300 bp in length, contained a large single-copy (LSC) region of 84,031 bp and a small single-copy (SSC) region of 18,269 bp. These two regions were separated by a pair of inverted repeat regions (IRa and IRb), each of them 25,000 bp in length. A total of 134 functional genes were encoded, consisted of 89 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The overall GC content of the chloroplast genome sequence was 37.3%, and the GC contents of the LSC, SSC, and IR regions were 35.2%, 31.2%, and 43.0%, respectively.

Evidence for Cross-Species Transmission of Covert Mortality Nodavirus to New Host of Mugilogobius abei.

Viral covert mortality disease (VCMD), caused by covert mortality nodavirus (CMNV), is a newly emerging disease affecting most cultured shrimp and other crustaceans, but not fish. However, we discovered for the first time that Mugilogobius abei, a common marine fish collecting from shrimp farming ponds and surrounding coastal waters in China, was tested to be CMNV positive based on reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay. Further investigation based on the quantitative RT-LAMP assay indicated that 39% individuals of sampled M. abei were CMNV positive. Sequencing and alignment of sequences revealed that the partial RNA-dependent RNA polymerase gene of CMNV isolated from M. abei shared 98% homology with that from the original CMNV isolates. Histopathological analysis showed that CMNV infection in M. abei could induce extensive skeletal muscle necrosis, nervous tissue vacuolation in retina of eye and cerebellum of brain. Positive signals were verified in skeletal muscle, eye, brain and intestine by in situ hybridization (ISH) with CMNV probes. Under transmission electron microscope (TEM), CMNV particles were further visualized in the cytoplasm of neurogliocytes, granulocytes and myocytes in the CMNV positive samples diagnosed by ISH. All findings suggested that CMNV, a typical alphanodavirus originated from shrimp, could switch their hosts to fish by cross-species transmission. Meanwhile, the results reminded us to pay close attention to the high risk of CMNV to use fish as intermediate or new host as well as potentially spread or cause epidemic among cultured marine fish.

Characterization of a new member of Iridoviridae, Shrimp hemocyte iridescent virus (SHIV), found in white leg shrimp (Litopenaeus vannamei).

A newly discovered iridescent virus that causes severe disease and high mortality in farmed Litopenaeus vannamei in Zhejiang, China, has been verified and temporarily specified as shrimp hemocyte iridescent virus (SHIV). Histopathological examination revealed basophilic inclusions and pyknosis in hematopoietic tissue and hemocytes in gills, hepatopancreas, periopods and muscle. Using viral metagenomics sequencing, we obtained partial sequences annotated as potential iridoviridae. Phylogenetic analyses using amino acid sequences of major capsid protein (MCP) and ATPase revealed that it is a new iridescent virus but does not belong to the five known genera of Iridoviridae. Transmission electron microscopy showed that the virus exhibited a typical icosahedral structure with a mean diameter of 158.6 ± 12.5 nm (n = 30)(v-v) and 143.6 ± 10.8 nm (n = 30)(f-f), and an 85.8 ± 6.0 nm (n = 30) nucleoid. Challenge tests of L. vannamei via intermuscular injection, per os and reverse gavage all exhibited 100% cumulative mortality rates. The in situ hybridization showed that hemopoietic tissue, gills, and hepatopancreatic sinus were the positively reacting tissues. Additionally, a specific nested PCR assay was developed. PCR results revealed that L. vannamei, Fenneropenaeus chinensis, and Macrobrachium rosenbergii were SHIV-positive, indicating a new threat existing in the shrimp farming industry in China.

LncRNA HOTAIR alleviates rheumatoid arthritis by targeting miR-138 and inactivating NF-κB pathway.

Rheumatoid arthritis (RA) is a chronic and autoimmune-mediated inflammatory disease. We aimed to investigate the regulation of lncRNA HOTAIR in LPS-treated chondrocytes and RA mouse. Our results showed that HOTAIR expression was significantly reduced in LPS-treated chondrocytes. The HOTAIR was then over-expressed in chondrocytes by transfecting recombinant lentivirus carrying sequences encoding HOTAIR. The LPS-induced reduction of cell proliferation rate and production of two inflammatory factors interleukin (IL)-17, IL-23 were markedly inhibited. Enforced expression of HOTAIR also led to the upregulation of proliferation-related protein Ki67 and proliferating cell nuclear antigen (PCNA). Moreover, a negative correlation was detected between the expression of HOTAIR and microRNA (miR)-138, and the expression of miR-138 was significantly increased in LPS-induced chondrocytes. The effects of HOTAIR over-expression on the proliferation and inflammation were partly reversed by miR-138 overexpression. Furthermore, the overexpression of HOTAIR significantly inhibited the activation of nuclear transcription factor-κB (NF-κB) in LPS-treated chondrocytes by suppressing p65 to cell nucleus, resulting in the down-regulation of IL-1ß and tumor necrosis factor (TNF)-α. In addition, the in vivo experiments exhibited that overexpression of HOTAIR increased cell proliferation and inhibited inflammation in RA rats, which were demonstrated by upregulation of Ki67 and PCNA, reduced CD4+IL-17+,CD4+IL-23+ cells, and down-regulation of p-p65, IL-1ß and TNF-α. In summary, our study suggests HOTAIR plays a protective role in RA by increasing proliferation rate and inhibiting inflammation, which may be related with the regulation of miR-138 expression and NF-κB signaling pathway. These results suggest that the regulation of HOTAIR may be a promising therapeutic strategy for RA.

Type D personality negatively associated with self-care in Chinese heart failure patients.

BACKGROUND: Little is known about the association between type D personality and self-care behaviors in heart failure (HF) patients. We examined the effect of type D personality on self-care behaviors and self-efficacy among Chinese HF patients. METHODS: A cross-sectional study with a convenience sample was conducted. All participants completed the questionnaires of the self-care of HF index (V6) and type D personality scale. Demographic and clinical variables were obtained from medical records and patient interviews. The methods used for data analysis included descriptive analysis, independent-sample t-test, χ (2) test, and multiple linear regression. RESULTS: A total of 127 HF patients were included and 61.4% of them were male. The average age for this study sample was 64.9 ± 12.34 years. The majority of the participants were in a New York Heart Association class III or IV (87%), and the average length of living with HF was 38.24 ± 41.1 months. A total of 33.1% of the participants were identified as having type D personality. No significant differences were determined in the demographic and clinical variables between type D and non-type D patients, except for the mean age and the length of living with HF. Type D patients were younger and had a shorter time of living with HF than their non-type D counterparts. Multiple regression demonstrated significant associations between type D personality and self-care maintenance and self-efficacy after adjusting the demographic and clinical factors. However, type D personality was not significantly associated with self-care management behaviors. CONCLUSIONS: Type D personality was negatively related to self-care maintenance and self-efficacy in Chinese HF patients. Future study is warranted to develop a tailored intervention to improve engagement in self-care behaviors in HF patients with type D personality.

Nursing students' knowledge and attitudes toward urinary incontinence: A cross-sectional survey.

BACKGROUND: Nurses must have adequate knowledge to manage the complexities of urinary incontinence. Nursing students are the nurses of the future, yet little is known about urinary incontinence education in undergraduate nursing programs. OBJECTIVES: The aim of this study was (a) to assess the knowledge and attitudes of urinary incontinence held by undergraduate nursing students in China and (b) to explore the relationship between knowledge, attitudes and socio-demographic characteristics. DESIGN: A cross-sectional survey using cluster random sampling. SETTINGS: Undergraduate departments of Nursing within the Faculty of Health Sciences at six Universities, located in different areas of China. PARTICIPANTS: A random selection of 6 faculties with a total of 1313 full time undergraduate nursing students completed the survey. METHODS: Self-reported data were collected using two validated questionnaires, the Urinary Incontinence Knowledge Scale and the Urinary Incontinence Attitude Scale, to access students' knowledge and attitudes toward urinary incontinence. RESULTS: Overall urinary incontinence knowledge was poor (49.9%, 15.0/30) and attitudes about urinary incontinence were generally positive (71.7%, 43.0/60). A high level of interest in learning more about urinary incontinence was found. There was a weak correlation between urinary incontinence knowledge and attitudes (r=0.135, p<0.01). There was also a significant positive correlation between urinary incontinence knowledge and attitudes and nursing students' year of study, urinary incontinence education and training, and formal clinical practicum experience in urology (p<0.05). CONCLUSIONS: Chinese nursing students showed poor urinary incontinence knowledge but generally positive attitudes toward urinary incontinence. This study suggests there is a need to examine urinary incontinence content throughout undergraduate nursing curricula in China.

Sensitive fluorescence detection of lysozyme using a tris(bipyridine)ruthenium(II) complex containing multiple cyclodextrins.

A new series of photoactive metallocyclodextrins with increased fluorescence intensity upon binding with ssDNAs/aptamers has been demonstrated to sensitively and selectively detect lysozyme. The detection mechanism relies on the formation of an aptamer-lysozyme complex, which leads to reduction of fluorescence intensity.