Pyrazolone-Protein Interaction Enables Long-Term Retention Staining and Facile Artificial Biorecognition on Cell Membranes.

Cell membrane genetic engineering has been utilized to confer cell membranes with functionalities for diagnostic and therapeutic purposes but concerns over cost and variable modification results. Although nongenetic chemical modification and phospholipid insertion strategies are more convenient, they still face bottlenecks in either biosafety or stability of the modifications. Herein, we show that pyrazolone-bearing molecules can bind to proteins with high stability, which is mainly contributed to by the multiple interactions between pyrazolone and basic amino acids. This new binding model offers a simple and versatile noncovalent approach for cell membrane functionalization. By binding to cell membrane proteins, pyrazolone-bearing dyes enabled precise cell tracking in vitro (>96 h) and in vivo (>21 days) without interfering with the protein function or causing cell death. Furthermore, the convenient anchor of pyrazolone-bearing biotin on cell membranes rendered the biorecognition to avidin, showing the potential for artificially creating cell targetability.

Efficacy of salvage surgery versus re-irradiation for isolated regional lymph node recurrence in patients with nasopharyngeal carcinoma.

BACKGROUND: To compare the clinical characteristics and prognoses of patients with isolated regional lymph node recurrent nasopharyngeal carcinoma (irrNPC) who underwent surgery or re-irradiation treatment. METHODS: We retrospectively reviewed 124 irrNPC patients who underwent initial radiotherapy between January 2010 and December 2020. The staging of regional lymph node recurrence was as follows: 75.8% for rN1, 14.5% for rN2, and 9.7% for rN3. Fifty-five patients underwent regional lymph node surgery (Surgery group), and sixty-nine patients received salvage radiotherapy with or without chemotherapy (Re-irradiation group). The survival rate was compared using Kaplan‒Meier analysis and evaluated by the log-rank test. Cox proportional hazard models were used to analyze prognostic factors. RESULTS: The median follow-up time was 70 months, the 5-year overall survival (OS) was 74%, and the median survival time was 60.8 months. There were no significant differences in 5-year OS (75.6% vs. 72.4%, P = 0.973), regional recurrence-free survival (RRFS, 62.7% vs. 71.1%, P = 0.330) or distant metastasis-free survival (DMFS, 4.2% vs.78.7%, P = 0.677) between the Surgery group and Re-irradiation group. Multivariate analysis revealed age at recurrence, radiologic extra-nodal extension (rENE) status, and recurrent lymph node (rN) classification as independent prognostic factors for OS. The rENE status was an independent prognostic factor for DMFS. Subgroup analysis of the Surgery group revealed that the rN3 classification was an adverse prognostic factor for OS. Age at recurrence ≥ 50 years, GTV-N dose, and induction chemotherapy were found to be independent prognostic factors for OS, RRFS, and DMFS, respectively, in the Re-irradiation group. CONCLUSIONS: For NPC patients with isolated regional lymph node recurrence after initial radiotherapy, those who underwent surgery had survival prognosis similar to those who underwent re-radiotherapy with or without chemotherapy. A prospective study is needed to validate these findings.

Optimization of collimator angle combined island blocking with parked gap achieves superior normal tissue sparing in SBRT planning of multiple liver lesions.

PURPOSE: To propose an efficient collimator angle optimization method by combining island blocking (IB) and parked gap (PG) problem to reduce the radiotherapy dose for normal tissue. The reduction will be done with single-isocenter multi-lesion volumetric modulated arc therapy (VMAT) for the stereotactic body radiation therapy (SBRT) of liver cancer. METHODS: A novel collimator angle optimization algorithm was developed based on the two-dimensional projection of targets on a beam's eye view (BEV) plane as a function of gantry and collimator angle. This optimization algorithm minimized the sum of the combined IB and PG (IB & PG) areas from all gantry angles for each arc. For comparison, two SBRT plans were respectively generated for each of the 20 retrospective liver cancer cases with multiple lesions. One plan was optimized using the IB & PG algorithm, and the other plan was optimized with a previously reported optimization algorithm that only considered the IB area. Plans were then evaluated and compared using typical dosimetric metrics. RESULTS: With the comparable target coverage, IB & PG plans had significantly lower D500cc, D700cc, mean dose (Dmean), and V15 of normal liver tissues when compared to IB plans. The median percent reductions were 3.32% to 5.36%. The D1cc, D5cc, and Dmean for duodenum and small intestine in IB & PG plans were significantly reduced in a range from 7.60% up to 16.03%. Similarly, the median integral dose was reduced by 3.73%. Furthermore, the percentage of normal liver Dmean sparing when IB & PG plans compared to IB plans, was found to be positively correlated (ρ = 0.669, P = 0.001) with the inter-target distance. CONCLUSION: The proposed IB & PG algorithm has been demonstrated to outperform the IB algorithm in almost all normal tissue sparing, and the magnitude of liver sparing was positively correlated with inter-target distance.

A Novel Shunt Zigzag Double-Tap Low-Harmonic Multi-Pulse Rectifier Based on a Three-Stage Power Electronic Phase-Shifting Transformer.

To solve the problem of the large size of traditional industrial frequency phase-shift transformers and the harmonic distortion of multi-pulse wave rectifier systems, this paper proposes a three-stage shunt zigzag power electronic phase-shift transformer based on a double-tap multi-pulse wave rectifier, which combines the power factor correction (PFC) converter with the voltage-type SPWM inverter circuit to form a power electronic converter to realize the frequency boost and power factor correction. Through AC-DC-AC conversion, the frequency of the three-phase AC input voltage is increased, the number of core and coil turns in the transformer is reduced to reduce the size of the phase-shifter transformer, a zigzag structure of the phase-shifter transformer is used to solve the unbalanced distribution of current between the diode bridges, and a passive harmonic suppression method on the DC side is used to generate a loop current by using a group of single-phase rectifier bridges to regulate the input line current of the phase-shifter transformer. The phase-shifted voltage is input into two three-phase diode rectifier bridges to rectify and supply power to the load. Simulation and semi-physical test results show that the proposed method reduces the total harmonic distortion (THD) value of the input current of the phase-shifted transformer to 7.17%, and the THD value of the grid-side input current is further reduced to 2.49%, which meets the harmonic standard and realizes the purpose of power factor correction as well as being more suitable for high-power applications.

Theabrownins in dark tea form complexes with tea polysaccharide conjugates.

BACKGROUND: Theabrownins (TBs) are one of most important quality components in dark tea, but have not been produced industrially. In this study, the aqueous extract was obtained from Pu-erh ripe tea, one kind of dark tea. Caffeine, theaflavin, catechin and saponin were removed by trichloromethane, ethyl acetate and n-butanol in turn to obtain a TB isolate. The TB isolate was subjected to column chromatography using a macroporous resin HPD-750 and eluted with a gradient of 0-700 g kg-1 ethanol aqueous solution. Four fractions were obtained, and named as TBs-FC1, TBs-FC2, TBs-FC3 and TBs-FC4. RESULTS: These four fractions contained polysaccharides and no small molecules such as catechins, caffeine and theaflavins as well as average molecular weights of 123.000 kDa, 23.380 kDa, 89.870 kDa and 106.600 kDa. It was revealed that they were complexes of TBs and tea polysaccharide conjugates (TPCs). Ultraviolet-visible (UV-visible) and infrared (IR) spectra showed the properties of TBs and TPCs. Their zeta potentials ranged from -13.40 mV to -38.80 mV in aqueous solutions at pH 3.0-9.0. CONCLUSION: This study reveals that TBs do not exist in free state but in combined state in dark tea, which provide the theoretical basis for the industrialization of TBs. © 2024 Society of Chemical Industry.

Assessment of the response characteristics of pollution load in Huntai Basin under climate change.

This study establishes a calibrated SWAT (Soil and Water Assessment Tool) model for the Huntai Basin, driven by SSP126, SSP245, SSP585, and multi-model ensemble (MME) models in CMIP6 (Coupled Model Intercomparison Project-6), to investigate the effects of climate change on hydrological processes and pollution load in the Huntai Basin. The results show that the annual mean temperature and the annual precipitation will gradually increase. The nitrogen and phosphorus pollution loads in the basin exhibit a trend of decreasing-increasing-decreasing. The correlation between the nitrogen-phosphorus pollution load and the hydrological process strengthens with increasing radiative forcing. In the four scenarios, CO2 is a primary driving factor that contributes greatly to nitrogen and phosphorus pollution. The main differences are in the total driving factors, and SSP126 and SSP245 are less than those of other models. The total phosphorus and total nitrogen pollution in different climate models were higher than the average level during the benchmark period, except for ammonia nitrogen pollution, which was lower. The nitrogen and phosphorus pollution in SSP126 and SSP245 modes will reach the maximum in 2040s, and the pollution in other periods will be lower than that in SSP585 and MME scenarios. In the long run, the development state between SSP126 and SSP245 may be better appropriate for the Huntai Basin's future sustainable development. This paper analyzes the occurrence and influencing factors of nitrogen and phosphorus pollution under climate change to provide reference to the protection of water environment under changing environments.

Spatiotemporal variability and environmental effects of greenhouse gases, nutrients, and dissolved carbons in an ice-covered reservoir.

Ice cover restructures the distribution of substances in ice and underlying water and poses non-negligible environmental effects. This study aimed to clarify the spatiotemporal variability and environmental effects of methane (CH4), nitrous oxide (N2O), total nitrogen (TN), total phosphorus (TP), dissolved organic carbon (DOC), and dissolved inorganic carbon (DIC) in ice and water columns during different ice-covered periods. We surveyed the ice-growth, ice-stability, and ice-melt periods in an ice-covered reservoir located in Northeast China. The results showed that underlying water (CH4: 1218.9 ± 2678.9 nmol L-1 and N2O: 19.3 ± 7.3 nmol L-1) and ice (CH4: 535.2 ± 2373.1 nmol L-1 and N2O: 9.9 ± 1.5 nmol L-1) were sources of atmospheric greenhouse gases. N2O concentrations were the highest in the bottom water of the reservoir while CH4 accumulated the most below the ice in the riverine zone. These can be attributed to differences in the solubilities and relative molecular masses of the two gases. Higher concentrations of N2O, TN, TP, DOC, and DIC were recorded in the underlying water than those in the ice due to the preferential redistribution of these substances in the aqueous phase during ice formation. Additionally, we distinguished between bubble and no-bubble areas in the riverine zone and found that the higher CH4 concentrations in the underlying water than those in the ice were due to CH4 bubbles. In addition, we reviewed various substances in ice-water systems and found that the substances in ice-water systems can be divided into solute exclusion and particle entrapment, which are attributed to differences between dissolved and particulate states. These findings are important for a comprehensive understanding of substances dynamics during ice-covered periods.

Effect of the bonding layer and multigrading layers on the performance of a wafer-bonded InGaAs/Si single-photon detector.

A wafer-bonded InGaAs/Si avalanche photodiode (APD) at a wavelength of 1550 nm was theoretically simulated. We focused on the effect of the I n 1-x G a x A s multigrading layers and bonding layers on the electric fields, electron and hole concentrations, recombination rates, and energy bands. In this work, I n 1-x G a x A s multigrading layers inserted between Si and InGaAs were adopted to reduce the discontinuity of the conduction band between Si and InGaAs. A bonding layer was introduced at the InGaAs/Si interface to isolate the mismatched lattices to achieve a high-quality InGaAs film. In addition, the bonding layer can further regulate the electric field distribution in the absorption and multiplication layers. The wafer-bonded InGaAs/Si APD, structured by a polycrystalline silicon (poly-Si) bonding layer and I n 1-x G a x A s multigrading layers (x changes from 0.5 to 0.85), displayed the highest gain-bandwidth product (GBP). When the APD operates in Geiger mode, the single-photon detection efficiency (SPDE) of the photodiode is 20%, and the dark count rate (DCR) is 1 MHz at 300 K. Moreover, one finds that the DCR is lower than 1 kHz at 200 K. These results indicate that high-performance InGaAs/Si SPAD can be achieved through a wafer-bonded platform.

Number of positive lymph nodes combined with the logarithmic ratio of positive lymph nodes predicts long-term survival for patients with node-positive parotid gland carcinoma after surgery: a SEER population-based study.

PURPOSE: To evaluate the prognostic value of the number of positive lymph nodes (NPLN), the ratio of positive lymph nodes (pLNR), and the logarithmic ratio of positive lymph nodes (LODDS) in patients with parotid gland carcinoma. On this basis, establishing and validating an optimal nomogram. METHODS: A total of 895 patients with T1-4N1-3M0 parotid gland carcinoma were included in our study from the Surveillance, Epidemiology, and End Results (SEER) database. Patients' data were randomly assigned to the training cohort and the validation cohort by a ratio of 7:3. Univariate and multivariate COX regression analysis were used to explore the relationship between the study factors and the prognosis of parotid gland carcinoma, including overall survival (OS) and cause-specific survival (CSS). The Akaike Information Criterion (AIC) was used to evaluate model fit. Harrell's concordance index (C-index), integrated discrimination improvement (IDI), and net reclassification index (NRI) were used to evaluate the predictive ability of these models. The decision curve analysis was used to evaluate the clinical benefit of the nomograms compared with the TNM stage. RESULTS: NPLN, pLNR, and LODDS are independent risk factors for the prognostic of PGC. According to the AIC, C index, IDI, and NRI, the models combined with NPLN and LODDS were the best. The decision curves suggested that our nomograms had good predictive abilities for the prognosis of parotid gland carcinoma. CONCLUSION: The two nomograms which contained NPLN and LODDS had the potential to predict OS and CSS in patients with parotid gland carcinoma.

Development, Validation and Application of a Bridging ELISA for Detection of Antibodies against GQ1001 in Cynomolgus Monkey Serum.

Immunogenicity is a major issue associated with the PK, efficacy, and safety evaluation of therapeutic protein products during pre-clinical and clinical studies. A multi-tiered approach consisting of screening, confirmatory, and titration assays has been widely adopted for anti-drug antibody testing. GQ1001, a recombinant humanized anti-human epidermal growth factor receptor 2 monoclonal antibody covalently linked to a cytotoxin of DM1, possesses a novel format of antibody-drug conjugates. In this study, we reported the development, validation, and application of an acid-dissociation bridging enzyme-linked immunosorbent assay for the detection of antibodies against GQ1001 in cynomolgus monkey serum. The sensitivity of the screening assay was 126.141 ng/mL in undiluted serum. The screening assay and confirmatory assay were neither affected by the naïve monkey serum nor by 2% and 5% (v/v) erythrocyte hemolysates. Moreover, the assay was not subject to interference by 2500 ng/mL of human IgG1 in the samples. Drug interference at low positive control (150 ng/mL) and high positive control (8000 ng/mL) of anti-GQ1001 antibodies was not observed when GQ1001 concentrations were below 3.125 µg/mL and 100 µg/mL, respectively. Furthermore, no hook effect was observed for the positive antibodies in the concentration range of 8 to 64 µg/mL. The validated assay was, thereafter, successfully applied to a single-dose toxicity study of GQ1001. Anti-drug antibody positive rates among dosing animals and testing samples were reported, and no significant impact was found on toxicokinetic outcomes.

Interactions between tea polyphenols and nutrients in food.

Tea polyphenols (TPs) are important secondary metabolites in tea and are active in the food and drug industry because of their rich biological activities. In diet and food production, TPs are often in contact with other food nutrients, affecting their respective physicochemical properties and functional activity. Therefore, the interaction between TPs and food nutrients is a very important topic. In this review, we describe the interactions between TPs and food nutrients such as proteins, polysaccharides, and lipids, highlight the forms of their interactions, and discuss the changes in structure, function, and activity resulting from their interactions.

Transoral CO2 laser-modified posterior cordotomy combined with plasma ablation subtotal arytenoidectomy for bilateral vocal fold paralysis: A retrospective study.

OBJECTIVES: To investigate the effect of transoral CO2 laser-modified posterior cordotomy combined with plasma ablation subtotal arytenoidectomy for bilateral vocal fold paralysis (BVFP). DESIGN: A retrospective study with medical records from 2017 to 2021 in our hospital. SETTING: A single-centre study. PARTICIPANTS: This retrospective study included 22 patients with BVFP. They underwent transoral CO2 laser-modified posterior cordotomy combined with plasma ablation subtotal arytenoidectomy in our hospital from 2017 to 2021. MAIN OUTCOME MEASURES: Preoperative and postoperative swallowing and phonation functions were evaluated in all patients. RESULTS: All 22 patients with a tracheostomy were successfully decannulated within 6 months after surgery without subsequent revision operations, and the width of the posterior glottis was more than 3.9 mm in all patients when they inspired. The statistical analysis showed that there was no difference in vocal function and swallowing function in all patients compared to preoperative (p > .05). CONCLUSION: Transoral CO2 laser-modified posterior cordotomy combined with plasma ablation subtotal arytenoidectomy enlarges the posterior glottis in patients with BVFP, which maintains airway patency without significant worsening in voice and swallowing function.

ESIPT-Inspired Dual-Mode Photoswitches with Fast Molecular Isomerization in the Solid State.

Photoswitchable materials have attracted considerable attention in various fields. Developing excellent solid-state dual-mode photoswitches is an important but challenging task. Herein, we propose a new strategy to construct an excited-state intramolecular proton transfer (ESIPT) inspired photoswitch (DiAH-pht) that possesses aggregation-induced emission (AIE) features and displays a fast molecular isomerization process characterized by dual-mode behavior in the solid state. Mechanistic studies indicate that introduction of a bulky group can create a folded molecular conformation that provides adequate volume to facilitate photoisomerization and the enhanced ESIPT effect can boost the isomerization process. The feasibility of our strategy was further demonstrated by the activated photoisomerization performance of the Schiff base derivatives. Furthermore, DiAH-pht shows good performance in the fields of dual-mode information encryption and high-density data storage.

Janus-Type ESIPT Chromophores with Distinctive Intramolecular Hydrogen-bonding Selectivity.

Excited-state intramolecular proton transfer (ESIPT)-based solid luminescent materials with multiple hydrogen bond acceptors (HBAs) remain unexplored. Herein, we introduced a family of Janus-type ESIPT chromophores featuring distinctive hydrogen bond (H-bond) selectivity between competitive HBAs in a single molecule. Our investigations showed that the central hydroxyl group preferentially forms intramolecular H-bonds with imines in imine-modified 2-hydroxyphenyl benzothiazole (HBT) chromophores but tethers the benzothiazole moiety in hydrazone-modified HBT chromophores. Imine-derived HBTs generally exhibit higher fluorescence efficiency, while hydrazone-derived HBTs show a reduced overlap between the absorption and fluorescence bands. Quantum chemical calculations unveiled the molecular origins of the biased intramolecular H-bonds and their impact on the ESIPT process. This Janus-type ESIPT chromophore skeleton provides new opportunities for the design of solid luminescent materials.

ANLN and UBE2T are prognostic biomarkers associated with immune regulation in breast cancer: a bioinformatics analysis.

OBJECTIVES: To screen and verify differential genes affecting the prognosis of breast cancer. METHODS: Breast cancer gene expression datasets were downloaded from the GEO database, and original data were analyzed in R. The TIMER database was used to analyze the relationship between ANLN and UBE2T and immune cell infiltration. RESULTS: Ten hub-key genes were identified, and survival analysis showed that UBE2T and ANLN were upregulated in breast cancer and their upregulation was associated with a poor prognosis. ANLN and UBE2T upregulation was associated with the prevalence of Th1 and Th2 cells, shifting the Th1/Th2 balance to Th2 in Basal and Luminal-B breast cancers, which indicates a poor prognosis (P < 0.05). CONCLUSION: ANLN and UBE2T are potential biomarkers for predicting the prognosis of breast cancer.

A retrospective study of 44 patients with head and neck Castleman's disease.

PURPOSE: To explore the clinical and pathological features, therapy and prognosis of Castleman's disease (CD) in the head and neck. METHODS: We retrospectively analyzed the clinical and pathological data of 44 patients with head and neck CD who were diagnosed in the Fujian Medical University Union hospital (Fujian, China) between May 2008 and June 2021. According to the clinical classification, they were divided into two groups, the unicentric CD (UCD, n = 20) and the multicentric CD (MCD, n = 24). Their clinical features, imaging findings, laboratory examination, and treatment results were, respectively, analyzed. RESULTS: The age of UCD patients was younger than that of MCD patients. Most of the UCD patients (80%) were female, with asymptomatic single lymphadenectasis, and the prognosis was favorable; while 70.8% of the MCD patients were male, with multiple lymph nodes throughout the body, and more prone to hepatosplenomegaly, pneumonia, serous effusion, anemia, hypoalbuminemia, elevated globulin, coagulation disorders, etc., the prognosis was bleak. Two cases of MCD patients were with systemic lupus erythematosus (SLE). CONCLUSIONS: UCD usually manifests as asymptomatic single lymph node enlargement, complete surgical resection was the mainstay of treatment modality. MCD has relatively complicated clinical symptoms and poor prognosis, and anti-IL-6 therapy may be effective.

Physicochemical and Colon Cancer Cell Inhibitory Properties of Theabrownins Prepared by Weak Alkali Oxidation of Tea Polyphenols.

Existing studies on the biological activity of theabrownins are not based on their free state but on the complexes of theabrownins, polysaccharides, proteins, and flavonoids. In this study, theabrownins (TBs-C) were prepared by weak alkali oxidation of tea polyphenols. The ultraviolet-visible scanning spectrum of TBs-C showed two characteristic absorption peaks at 203 and 270 nm. The zeta potential of the TBs-C aqueous solution was negative, and the values varied from - 6.26 to -19.55 mV with a solution pH of 3-9. Storage conditions of pH 5.0-7.0 and around 25 °C were beneficial for the physical and chemical stability of the TBS-C solution. Cells were treated with series concentrations and examined by MTT, HE staining, PI immunofluorescence staining, flow cytometry, and real-time PCR to investigate the antiproliferative effect of TBs-C on human colon cancer HT-29 cells. The results showed that TBs-C, particularly at 500 µg/mL, inhibited cell growth. TBs-C induced HT-29 cell apoptosis, as confirmed by morphological changes, nucleus propidium iodide staining, and distributions of the cell cycle. The apoptotic mechanism may be due to the intracellular redox imbalance induced by TBs-C.

Design of a Metallacycle-Based Supramolecular Photosensitizer for In Vivo Image-Guided Photodynamic Inactivation of Bacteria.

Bacterial infection is one of the greatest threats to public health. In vivo real-time monitoring and effective treatment of infected sites through non-invasive techniques, remain a challenge. Herein, we designed a PtII metallacycle-based supramolecular photosensitizer through the host-guest interaction between a pillar[5]arene-modified metallacycle and 1-butyl-4-[4-(diphenylamino)styryl]pyridinium. Leveraging the aggregation-induced emission supramolecular photosensitizer, we improved fluorescence performance and antimicrobial photodynamic inactivation. In vivo studies revealed that it displayed precise fluorescence tracking of S. aureus-infected sites, and in situ performed image-guided efficient PDI of S. aureus without noticeable side effects. These results demonstrated that metallacycle combined with host-guest chemistry could provide a paradigm for the development of powerful photosensitizers for biomedicine.

Photostimulated Spiropyran for Instantaneous Visualization of Thermal Field Distribution and Flow Pattern.

The study of thermocapillary convection has attracted the attention of researchers due to the importance in both fundamental and industrial aspects. To trace the state of flows in real time during thermocapillary convection, the development of imaging methods and tools is essential. Here we use a benzothiazole unit-bearing spiropyran (BS1-SP) as a photostimulated indicator to visualize the details of instantaneous temperature distribution and flow pattern on the surface of volatile solvent simultaneously with a high spatial and temporal resolution during convection. This work provides insights into dynamic self-organization and thermo-hydrodynamics taking place in evaporating systems, and a useful tool to study these behaviors.

Sanger's Reagent Sensitized Photocleavage of Amide Bond for Constructing Photocages and Regulation of Biological Functions.

Photolabile groups offer promising tools to study biological processes with high spatial and temporal control. In the investigation, we designed and prepared several new glycine amide derivatives of Sanger's reagent and demonstrated that they serve as a new class of photocages for Zn2+ and an acetylcholinesterase (AChE) inhibitor. We showed that the mechanism for photocleavage of these substances involves initial light-driven cyclization between the 2,4-dinitrophenyl and glycine methylene groups to form acyl benzimidazole N-oxides, which undergo secondary photoinduced decarboxylation in association with rupture of an amide bond. The cleavage reactions proceed with modest to high quantum yields. We demonstrated that these derivatives can be used in targeted intracellular delivery of Zn2+, fluorescent imaging by light-triggered Zn2+ release, and regulation of biological processes including the enzymatic activity of carbonic anhydrase (CA), negative regulation of N-methyl-d-aspartate receptors (NMDARs), and pulse rate of cardiomyocytes. The successful proof-of-concept examples described above open a new avenue for using Sanger's reagent-based glycine amides as photocages for the exploration of complex cellular functions and signaling pathways.