A cross-sectional study of the association between frequency of telecommuting and unhealthy dietary habits among Japanese workers during the COVID-19 pandemic.

OBJECTIVE: Due to the COVID-19 pandemic, telecommuting has become a new way of working that has not only changed individuals' work, but also their health and lifestyle. We examined the relationship between telecommuting frequency and unhealthy dietary habits among Japanese workers. METHODS: A total of 33,302 workers completed an Internet survey about telecommuting and dietary habits. Data from 13,468 office workers who telecommuted were analyzed. Telecommuting frequency during the COVID-19 pandemic was extracted from a questionnaire. The odds ratios (ORs) of four types of dietary habits, namely, skipping breakfast, solitary eating, lower meal frequency, and meal substitution associated with telecommuting frequency were estimated using multilevel logistic regression nested in the prefecture of residence to control for differences in residential area. RESULTS: The multivariate OR of skipping breakfast was 1.15 (95% CI: 1.03-1.29, p = .013) for participants who telecommuted in excess of four days per week compared to those who rarely telecommuted. Similarly, the OR of solitary eating, lower meal frequency and meal substitution were 1.44 (95% CI: 1.28-1.63, p < .001), 2.39 (95% CI: 1.66-3.44, p < .001), and 1.26 (95% CI: 1.04-1.51, p = .015) for those who telecommuted in excess of four days per week compared to those who rarely telecommuted. There was a statistically significant increase in the dose-response trend in ORs of solitary eating (p for trend <.001), lower meal frequency (p for trend <.001), and meal substitution (p for trend = .001) with increasing telecommuting frequency. CONCLUSION: Telecommuters may develop unhealthy dietary habits, indicating the need for strategies to help telecommuters manage their nutrition and diet.

Fate Decision Between Group 3 Innate Lymphoid and Conventional NK Cell Lineages by Notch Signaling in Human Circulating Hematopoietic Progenitors.

The role of Notch signaling in human innate lymphoid cell (ILC) differentiation is unclear, although IL-7 and IL-15 promote differentiation of natural cytotoxicity receptor (NCR) NKp44+ group 3 ILCs (NCR+ILC3s) and conventional NK (cNK) cells from CD34+ hematopoietic progenitor cells (HPCs) ex vivo. In this study, we analyzed the functions of Notch in the differentiation of NCR+ILC3s and cNK cells from human HPC subpopulations circulating in peripheral blood by limiting dilution and clonal assays using high-throughput flow cytometry. We demonstrated that Notch signaling in combination with IL-7 induced NCR+ILC3 differentiation, but conversely suppressed IL-15-dependent cNK cell generation in CD45RA+Flt-3-c-Kitlow, a novel innate lymphocyte-committed HPC subpopulation. In contrast, Notch signaling induced CD45RA-Flt-3+c-Kithigh multipotent HPCs to generate CD34+CD7+CD62Lhigh, the earliest thymic progenitor-like cells, which preserved high cNK/T cell potential, but lost NCR+ILC3 potential. These findings implicate the countervailing functions of Notch signaling in the fate decision between NCR+ILC3 and cNK cell lineages at different maturational stages of human HPCs. Inhibition of Notch functions by Abs specific for either the Notch1 or Notch2 negative regulatory region suggested that both Notch1 and Notch2 signals were involved in the fate decision of innate lymphocyte-committed HPCs and in the generation of earliest thymic progenitor-like cells from multipotent HPCs. Furthermore, the synergistic interaction between Notch and IL-7 in NCR+ILC3 commitment was primarily explicable by the induction of IL-7 receptor expression in the innate lymphocyte-committed HPCs by Notch stimulation, suggesting the pivotal role of Notch in the transcriptional control required for human NCR+ILC3 commitment.

Skeletal muscle loss and prognosis of breast cancer patients.

PURPOSE: The aim of this study was to clarify the changes in the cross-sectional area of skeletal muscle and muscle attenuation (MA) during 12-month period before death in breast cancer patients. METHODS: Breast cancer patients who received treatment between September 2002 and July 2014 at Shizuoka Cancer Center or between December 2005 and July 2014 at Teikyo University Hospital were identified. Computed tomography (CT) scans during the 12-month period before death of consecutive female patients who died of breast cancer were reviewed. Skeletal muscle quantity and quality were evaluated by a cross-sectional area of skeletal muscle and MA, respectively, on CT scans taken 10-12 months (T1), 7-9 months (T2), 4-6 months (T3), and within 3 months (T4) prior to death. Wilcoxon signed rank test was used to compare the differences between the two-time points with Bonferroni correction (p = 0.0083). RESULTS: The medical records of 99 patients (median age at death, 57 years; range, 40-83 years) were retrospectively analyzed. Both the cross-sectional area and MA continued to decrease during 12-month period before death. Statistically significant differences were observed in the cross-sectional areas between T1 and T4 (p = 0.0011), T2 and T4 (p = 0.0019), and T3 and T4 (p = 0.0026), as well as in MA between T2 and T4 (p = 0.0012) and T3 and T4 (p = 0.0061). CONCLUSIONS: These results suggest that both quantity and quality of the skeletal muscle continued to decrease during 12-month period before death in breast cancer patients.

Exploring career anchors among occupational health nurses in Japan: A qualitative study.

AIM: This study examined the career anchor characteristics that are possessed by Japanese occupational health nurses. METHOD: Sixteen occupational health nurses participated in the semistructured interview. Data analyses were conducted using descriptive qualitative methods. RESULTS: The data showed the following five categories: practices concerning relationships and positions; development of occupational health practices; management skills for effective work; practices that are approved inside and outside the organization; and work and private life considerations. CONCLUSIONS: This study described the career anchors among occupational health nurses in Japan. The participants emphasized the following: the importance of maintaining good cooperative relationships with workers and supervisors; balancing professional and organized labor; and practicing effective occupational health services. Moreover, the occupational health nurses emphasized receiving approval from inside and outside of the organization. These results were consistent with the actual practices of occupational health nursing.

Development of the Career Anchors Scale among Occupational Health Nurses in Japan.

OBJECTIVES: This study aimed to develop the Career Anchors Scale among Occupational Health Nurses (CASOHN) and evaluate its reliability and validity. METHODS: Scale items were developed through a qualitative inductive analysis of interview data, and items were revised following an examination of content validity by experts and occupational health nurses (OHNs), resulting in a provisional scale of 41 items. A total of 745 OHNs (response rate 45.2%) affiliated with the Japan Society for Occupational Health participated in the self-administered questionnaire survey. RESULTS: Two items were deleted based on item-total correlations. Factor analysis was then conducted on the remaining 39 items to examine construct validity. An exploratory factor analysis with a main factor method and promax rotation resulted in the extraction of six factors. The variance contribution ratios of the six factors were 37.45, 7.01, 5.86, 4.95, 4.16, and 3.19%. The cumulative contribution ratio was 62.62%. The factors were named as follows: Demonstrating expertise and considering position in work (Factor 1); Management skills for effective work (Factor 2); Supporting health improvement in groups and organizations (Factor 3); Providing employee-focused support (Factor 4); Collaborating with occupational health team members and personnel (Factor 5); and Compatibility of work and private life (Factor 6). The confidence coefficient determined by the split-half method was 0.85. Cronbach's alpha coefficient for the overall scale was 0.95, whereas those of the six subscales were 0.88, 0.90, 0.91, 0.80, 0.85, and 0.79, respectively. CONCLUSIONS: CASOHN was found to be valid and reliable for measuring career anchors among OHNs in Japan.

Long-Term Effects of Radiation Exposure and Metabolic Status on Telomere Length of Peripheral Blood T Cells in Atomic Bomb Survivors.

In a series of studies of atomic bomb survivors, radiation-dose-dependent alterations in peripheral T-cell populations have been reported. For example, reduced size in naïve T-cell pools and impaired proliferation ability of T cells were observed. Because these alterations are also generally observed with human aging, we hypothesized that radiation exposure may accelerate the aging process of the T-cell immune system. To further test this hypothesis, we conducted cross-sectional analyses of telomere length, a hallmark of cellular aging, of naïve and memory CD4 T cells and total CD8 T cells in the peripheral blood of 620 atomic bomb survivors as it relates to age and radiation dose, using fluorescence in situ hybridization with flow cytometry. Since telomere shortening has been recently demonstrated in obesity-related metabolic abnormalities and diseases, the modifying effects of metabolic status were also examined. Our results indicated nonlinear relationships between T-cell telomere length and prior radiation exposure, i.e., longer telomeres with lower dose exposure and a decreasing trend of telomere length with individuals exposed to doses higher than 0.5 Gy. There were associations between shorter T-cell telomeres and higher hemoglobin Alc levels or fatty liver development. In naïve and memory CD4 T cells, radiation dose and high-density lipoprotein (HDL) cholesterol were found to positively interact with telomere length, suggesting that the decreasing trend of telomere length from a higher radiation dose was less conspicuous in individuals with a higher HDL cholesterol. It is therefore likely that radiation exposure perturbs T-cell homeostasis involving telomere length maintenance by multiple biological mechanisms, depending on dose, and that long-term-radiation-induced effects on the maintenance of T-cell telomeres may be modified by the subsequent metabolic conditions of individuals.

Fatigue and Sleep Among Employees With Prospective Increase in Work Time Control: A 1-Year Observational Study With Objective Assessment.

OBJECTIVES: This observational study aimed to determine how 1-year changes in work time control (WTC) have an impact upon objectively measured fatigue and sleep among employees. METHODS: Thirty-nine employees were divided into two groups according to whether or not their WTC increased from baseline to 1 year later. Psychomotor vigilance task (PVT) and wrist actigraphy were used to objectively measure fatigue and sleep, respectively. Self-reported outcomes were also measured. RESULTS: The increased WTC group showed gradual improvements in PVT performance and sleep quality over the course of the follow-up period compared with the not-increased WTC group. Between-group differences were statistically significant for PVT lapses and tended to be significant for PVT speed after 1 year. CONCLUSIONS: A progressive increase in WTC could play a crucial role in reducing fatigue and promoting sleep among employees.

Relationship between spontaneous γH2AX foci formation and progenitor functions in circulating hematopoietic stem and progenitor cells among atomic-bomb survivors.

Accumulated DNA damage in hematopoietic stem cells is a primary mechanism of aging-associated dysfunction in human hematopoiesis. About 70 years ago, atomic-bomb (A-bomb) radiation induced DNA damage and functional decreases in the hematopoietic system of A-bomb survivors in a radiation dose-dependent manner. The peripheral blood cell populations then recovered to a normal range, but accompanying cells derived from hematopoietic stem cells still remain that bear molecular changes possibly caused by past radiation exposure and aging. In the present study, we evaluated radiation-related changes in the frequency of phosphorylated (Ser-139) H2AX (γH2AX) foci formation in circulating CD34-positive/lineage marker-negative (CD34+Lin-) hematopoietic stem and progenitor cells (HSPCs) among 226Hiroshima A-bomb survivors. An association between the frequency of γH2AX foci formation in HSPCs and the radiation dose was observed, but the γH2AX foci frequency was not significantly elevated by past radiation. We found a negative correlation between the frequency of γH2AX foci formation and the length of granulocyte telomeres. A negative interaction effect between the radiation dose and the frequency of γH2AX foci was suggested in a proportion of a subset of HSPCs as assessed by the cobblestone area-forming cell assay (CAFC), indicating that the self-renewability of HSPCs may decrease in survivors who were exposed to a higher radiation dose and who had more DNA damage in their HSPCs. Thus, although many years after radiation exposure and with advancing age, the effect of DNA damage on the self-renewability of HSPCs may be modified by A-bomb radiation exposure.

Circulating Hematopoietic Stem and Progenitor Cells in Aging Atomic Bomb Survivors.

It is not yet known whether hematopoietic stem and progenitor cells (HSPCs) are compromised in the aging population of atomic bomb (A-bomb) survivors after their exposure nearly 70 years ago. To address this, we evaluated age- and radiation-related changes in different subtypes of circulating HSPCs among the CD34-positive/lineage marker-negative (CD34(+)Lin(-)) cell population in 231 Hiroshima A-bomb survivors. We enumerated functional HSPC subtypes, including: cobblestone area-forming cells; long-term culture-initiating cells; erythroid burst-forming units; granulocyte and macrophage colony-forming units; and T-cell and natural killer cell progenitors using cell culture. We obtained the count of each HSPC subtype per unit volume of blood and the proportion of each HSPC subtype in CD34(+)Lin(-) cells to represent the lineage commitment trend. Multivariate analyses, using sex, age and radiation dose as variables, showed significantly decreased counts with age in the total CD34(+)Lin(-) cell population and all HSPC subtypes. As for the proportion, only T-cell progenitors decreased significantly with age, suggesting that the commitment to the T-cell lineage in HSPCs continuously declines with age throughout the lifetime. However, neither the CD34(+)Lin(-) cell population, nor HSPC subtypes showed significant radiation-induced dose-dependent changes in counts or proportions. Moreover, the correlations of the proportions among HSPC subtypes in the survivors properly revealed the hierarchy of lineage commitments. Taken together, our findings suggest that many years after exposure to radiation and with advancing age, the number and function of HSPCs in living survivors as a whole may have recovered to normal levels.

Metastatic breast carcinoma of the abdominal wall muscle: a case report.

Metastasis from breast carcinoma is an uncommon occurrence in skeletal muscle, compared to local invasion into muscle from direct tumor spread. A 49-year-old woman was referred to our hospital with an 8.5-cm mass in the right breast. Core needle biopsy revealed metaplastic carcinoma with squamous metaplasia. The mass was rapidly growing and metaplastic, so mastectomy with dissection of axillary lymph nodes was performed. Pathological examination showed metaplastic carcinoma, histological grade 3, triple negative, and a MIB-1 labeling index of 80%. Six months postoperatively, during adjuvant chemotherapy treatment, she reported numbness and pain in the right lateral thigh and a mass in the right lower abdomen. Computed tomography revealed multiple lined masses in the abdominal wall and iliac muscle. Core needle biopsy showed metastatic breast carcinoma. Radio- and chemotherapy were administered, but the mass in the muscle became enlarged. To control her pain, a combined treatment with morphine, fentanyl, ketamine, antiepilepsy drug, and NSAIDs was administered. Liver metastasis appeared 9 months (15 months postoperatively) after recognition of muscle metastasis, and the patient died 16 months postoperatively. Skeletal muscle metastasis is uncommon, and therapeutic intervention is mainly palliative. The most common symptom of skeletal muscle metastasis is pain; thus, pain control is a pivotal goal of treatment.

Linkage between dendritic and T cell commitments in human circulating hematopoietic progenitors.

The relationships between commitments of dendritic cells (DCs) and T cells in human hematopoietic stem cells are not well understood. In this study, we enumerate and characterize conventional DC and plasmacytoid DC precursors in association with T cell and thymus-derived types of NK cell precursors among CD34(+) hematopoietic progenitor cells (HPCs) circulating in human peripheral blood. By limiting-dilution analyses using coculture with stroma cells expressing Notch1 ligand, the precursor frequencies (PFs) of DCs in HPCs were found to significantly correlate with T cell PFs, but not with NK cell PFs, among healthy donors. Clonal analyses showed that the majority of T/NK dual- and T single-lineage precursors-but only a minority of NK single-lineage precursors-were associated with the generation of DC progenies. All clones producing both DC and T cell progenies were found with monocyte and/or granulocyte progenies, suggesting DC differentiation via myeloid DC pathways. Analyses of peripheral blood HPC subpopulations revealed that the lineage split between DC and T/NK cell progenitor occurs at the stage prior to bifurcation into T and NK cell lineages. The findings suggest a strong linkage between DC and T cell commitments, which may be imprinted in circulating lymphoid-primed multipotent progenitors or in more upstream HPCs.

Inverse associations between obesity indicators and thymic T-cell production levels in aging atomic-bomb survivors.

Reduction of the naive T-cell population represents a deteriorating state in the immune system that occurs with advancing age. In animal model studies, obesity compromises the T-cell immune system as a result of enhanced adipogenesis in primary lymphoid organs and systemic inflammation. In this study, to test the hypothesis that obesity may contribute to the aging of human T-cell immunity, a thousand atomic-bomb survivors were examined for obesity status and ability to produce naive T cells, i.e., T-cell receptor excision circle (TREC) numbers in CD4 and CD8 T cells. The number of TRECs showed a strong positive correlation with naive T cell numbers, and lower TREC numbers were associated with higher age. We found that the TREC number was inversely associated with levels of obesity indicators (BMI, hemoglobin A1c) and serum CRP levels. Development of type-2 diabetes and fatty liver was also associated with lower TREC numbers. This population study suggests that obesity with enhanced inflammation is involved in aging of the human T-cell immune system. Given the fact that obesity increases the risk of numerous age-related diseases, attenuated immune competence is a possible mechanistic link between obesity and disease development among the elderly.

Age-associated changes in the differentiation potentials of human circulating hematopoietic progenitors to T- or NK-lineage cells.

Age-associated changes of T and NK cell (T/NK) potential of human hematopoietic stem cells are unknown. In this study, we enumerate and characterize T/NK precursors among CD34(+)Lin(-) cell populations circulating in normal human adult peripheral blood (PB) by a limiting-dilution assay using coculture with OP9-DL1 stroma cells expressing Notch 1 ligand, Delta-like 1. The frequency of T cell precursors in CD34(+)Lin(-) cells was found to decrease with donor age, whereas the ratio of NK to T cell precursor frequency (NK/T ratio) increased with age, suggesting that lymphoid differentiation potential of PB progenitors shifts from T to NK cell lineage with aging. Clonal analyses of CD34(+)Lin(-) cells showed that differences in the NK/T ratio were attributable to different distributions of single- and dual-lineage T/NK precursor clones. Because nearly all of the clones retained monocyte and/or granulocyte differentiation potentials in coculture with OP9-DL1 cells, T/NK precursors in PB are considered to be contained in the pool of T/NK/myeloid multipotent progenitors. The age-associated increase in NK over T cell commitment might occur in precursor cells with T/NK/myeloid potential.

[How are leisure activity and shiftwork schedule associated with recovery from fatigue in shiftwork nurses?].

OBJECTIVES: The period of leisure is an appropriate time to recover from work-induced fatigue, though some recovery takes place during rest breaks at work. Recently, much attention has been paid to the critical role of leisure activity in recovery. However, the findings relevant to shiftwork nurses who cannot take a day-off regularly are limited. This study explored how leisure activity during days off and shift work schedule are associated with recovery from fatigue in nurses working rotating shifts. METHODS: A total of 426 nurses working rotating shifts at a university hospital returned a questionnaire regarding leisure activity and fatigue (response rate: 81.5%). Nurses were eligible for this study if they were female, worked 2 or 3 shifts, and had no missing data. A total of 390 respondents satisfied the inclusion criteria. A factor analysis classified their responses on how to spend an assumed period of two consecutive days off into three activity types: outdoor-, sleep-, and indoor-oriented. Fatigue (recovery from fatigue, accumulated fatigue, burnout), work conditions (working time, overtime, nightshift napping), sleep (sleep duration before day shift or day off, sleepiness) were measured. These data were analyzed using a two-way mixed model analysis of covariance (type [outdoor, sleep, indoor], shift schedule [two or three-shift system]). Covariates included age, length of career, partner, children, and hospital ward. Multiple regression analyses were performed to examine the factors determining the level of fatigue. RESULTS: Outdoor-oriented nurses showed significantly faster fatigue recovery, lower accumulated fatigue and less burnout symptoms than others, regardless of the shiftwork schedule. In contrast, sleep-oriented nurses showed significantly slower recovery from fatigue. Besides, their level of fatigue deteriorated more when they worked under a 3-shift system (counter-clockwise) compared with under 2-shift system (with mainly 16-hour nightshift). Multiple regression analysis indicated that sleep-oriented type of leisure activity, workload perception of working time, work-induced insomnia and length of nightshift naps were significantly related to fatigue-related outcomes. CONCLUSIONS: The primary finding of this study suggests that the level of fatigue is associated with the type of leisure activity, especially sleep-oriented activity, during shiftwork nurses' days off. Also, ensuring sufficient nightshift nap time may be one of the most important nightshift-related factors for recovery from fatigue. The present findings may have implications for appropriate activities during days off as factors facilitating recovery from work, though further investigations are needed to examine the causal links.

T-cell immunosenescence and inflammatory response in atomic bomb survivors.

In this paper we summarize the long-term effects of A-bomb radiation on the T-cell system and discuss the possible involvement of attenuated T-cell immunity in the disease development observed in A-bomb survivors. Our previous observations on such effects include impaired mitogen-dependent proliferation and IL-2 production, decreases in naive T-cell populations, and increased proportions of anergic and functionally weak memory CD4 T-cell subsets. In addition, we recently found a radiation dose-dependent increase in the percentages of CD25(+)/CD127(-) regulatory T cells in the CD4 T-cell population of the survivors. All these effects of radiation on T-cell immunity resemble effects of aging on the immune system, suggesting that ionizing radiation might direct the T-cell system toward a compromised phenotype and thereby might contribute to an enhanced immunosenescence. Furthermore, there are inverse, significant associations between plasma levels of inflammatory cytokines and the relative number of naïve CD4 T cells, also suggesting that the elevated levels of inflammatory markers found in A-bomb survivors can be ascribed in part to T-cell immunosenescence. We suggest that radiation-induced T-cell immunosenescence may result in activation of inflammatory responses and may be partly involved in the development of aging-associated and inflammation-related diseases frequently observed in A-bomb survivors.

[A case of advanced rectal cancer with multiple liver metastases successfully treated by perioperative administration of UFT and oral leucovorin].

The patient was a sixty-five-year-old man who had an advanced rectal cancer (Ra, type 2) with liver metastases. Low anterior resection with lymphnode dissection (D3) was done, but hepatectomy was not performed because of the multiple metastases besides the five tumors detected preoperatively. The pathological finding was moderately-differentiated adenocarcinoma. He was treated with 5-FU via the hepatic artery, but the therapy failed due to catheter infection after 3 postoperative months. Then, he received general 5-FU/l-LV therapy intravenously from 3 to 8 months after the operation, and oral UFT/LV (Uzel®) from 9 to 22 months. Next, we switched to single UFT therapy at 23 months because CT findings showed remarkable calcification in the liver metastases. But only one tumor of the liver (S6) among liver metastases enlarged at 27 months. We switched the chemotherapy again to UFT/Uzel and mFOLFOX6, but decided to perform hepatectomy of S6/7 at 39 months since it proved ineffective. The pathological finding was 90% necrosis and calcification of the tumor. Metastasis of the right 10th rib was newly found and was removed at 63 months after the first operation. Now, NC in the liver is continued 67 months after the first operation, and the patient is doing well.

Memory CD4 T-cell subsets discriminated by CD43 expression level in A-bomb survivors.

PURPOSE: Our previous study showed that radiation exposure reduced the diversity of repertoires of memory thymus-derived cells (T cells) with cluster of differentiation (CD)- 4 among atomic-bomb (A-bomb) survivors. To evaluate the maintenance of T-cell memory within A-bomb survivors 60 years after radiation exposure, we examined functionally distinct memory CD4 T-cell subsets in the peripheral blood lymphocytes of the survivors. METHODS: Three functionally different subsets of memory CD4 T cells were identified by differential CD43 expression levels and measured using flow cytometry. These subsets consist of functionally mature memory cells, cells weakly responsive to antigenic stimulation, and those cells functionally anergic and prone to spontaneous apoptosis. RESULTS: The percentages of these subsets within the peripheral blood CD4 T-cell pool all significantly increased with age. Percentages of functionally weak and anergic subsets were also found to increase with radiation dose, fitting to a log linear model. Within the memory CD4 T-cell pool, however, there was an inverse association between radiation dose and the percentage of functionally mature memory cells. CONCLUSION: These results suggest that the steady state of T cell memory, which is regulated by cell activation and/or cell survival processes in subsets, may have been perturbed by prior radiation exposure among A-bomb survivors.

Caspase-independent cell death without generation of reactive oxygen species in irradiated MOLT-4 human leukemia cells.

To improve our understanding of ionizing radiation effects on immune cells, we investigated steps leading to radiation-induced cell death in MOLT-4, a thymus-derived human leukemia cell. After exposure of MOLT-4 cells to 4 Gy of X-rays, irradiated cells sequentially showed increase in intracellular reactive oxygen species (ROS), decrease in mitochondrial membrane potential, and eventually apoptotic cell death. In the presence of the caspase inhibitor z-VAD-fmk, irradiated cells exhibited necrotic characteristics such as mitochondrial swelling instead of apoptosis. ROS generation was not detected during this necrotic cell death process. These results indicate that radiation-induced apoptosis in MOLT-4 cells requires elevation of intracellular ROS as well as activation of a series of caspases, whereas the cryptic necrosis program--which is independent of intracellular ROS generation and caspase activation--is activated when the apoptosis pathway is blocked.

Optimization of evanescent-field fluorescence-assisted lectin microarray for high-sensitivity detection of monovalent oligosaccharides and glycoproteins.

Lectin microarray is an emerging technique, which will accelerate glycan profiling and discovery of glycan-related biomarkers. One of the most important stages in realizing the potential of the technique is to achieve sufficiently high sensitivity to detect even the low concentrations of some target glycoproteins which occur in sera or tissues. Previously, we developed a lectin microarray based on an evanescent-field fluorescence-assisted detection principle that allows rapid profiling of glycoproteins. Here, we report optimization of procedures for lectin spotting and immobilization to improve the sensitivity and reproducibility of the lectin microarray. The improved microarray allows high-sensitivity detection of even monovalent oligosaccharides that generally have a low affinity with lectins (K(d)>10(-6) M). The LOD observed for RCA120, a representative plant lectin, with asialofetuin, and an asialo-biantennary N-glycan probe were determined to be 100 pg/mL and 100 pM, respectively. With the improved lectin microarray system, closely related structural isomers, i.e., Le(a) and Le(x), were clearly differentiated by the difference in signal patterns on relevant multiple lectins, even though specific lectins to detect these glycan structures were not available. The result proved a previously proposed concept of lectin-based glycan profiling.