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Ting Chen

Publications and source records attributed to Ting Chen.

At least 37 records · Page 2Linked to original sources

Role of four major components in the effect of Si-Ni-San, a traditional Chinese prescription, against contact sensitivity in mice.

Previously, we demonstrated the inhibitory effects of Si-Ni-San, a traditional Chinese prescription, on picryl chloride-induced ear contact sensitivity (PCl-CS). This study aimed to evaluate the role of the four major constituents contained in the prescription (saikosaponins, paeoniflorin, naringin and glycyrrhizin) in the inhibitory effect. When administered during the induction phase, saikosaponin a and glycyrrhizin showed significant inhibitory effects, while paeoniflorin and naringin did not. These components in Si-Ni-San also inhibited the activation and proliferation of T lymphocytes as well as the production of cytokines such as tumour necrosis factor-alpha and interferon-gamma to different extents. Saikosaponin a and paeoniflorin dose-dependently reduced the splenocyte adhesion to type I collagen, while glycyrrhizin only showed a slight tendency. Furthermore, treatment with glycyrrhizin or saikosaponin a, rather than paeoniflorin or naringin, moderately inhibited the matrix metalloproteinase (MMP)-2 activity of the splenocytes from PCl-CS mice, and the combination of all four components showed a strong inhibition against MMP-2. Moreover, the components markedly decreased the serum level of nitric oxide in PCl-sensitized mice. The results indicated that saikosaponin a and glycyrrhizin may be the major contributors in the alleviation effect of Si-Ni-San on contact sensitivity, and paeoniflorin and naringin may exhibit a co-operative effect.

Animals↗

Electrochemistry of xanthine oxidase and its interaction with nitric oxide.

With the help of nanocrystalline TiO2, the direct electrochemistry of xanthine oxidase (XOD) was achieved and two pairs of redox waves were observed. The interaction between XOD and nitric oxide (NO) was also investigated. The experimental results reveal that NO can be reduced at a XOD-nano TiO2 film modified electrode. When the NO concentration was low, the reduced product, HNO, would inactivate the protein. However, when the NO concentration was high, HNO would continue to react with NO to form N2O2- and N3O3-, which would not inhibit XOD, and thus the amount of active protein did not decrease any further.

Animals↗

[Combination of growing culture transformation and resting cells transformation of Pseudomonas putida NA-1 for production of 6-hydroxynicotinic acid].

The current technology for microbial hydroxylation of nicotinic acid is a procedure of resting cells transformation. Here it was reported that non-degradation of 6-hydroxynicotinic acid during hydroxylation of nicotinic acid by resting cells was due to existing of nicotinic acid in the transformation mixture, not the death of cells. Therefore it was attempted that the induced cultivation of Pseudomonas putida NA-1 for hydroxylation activity by nicotinic acid was used for accumulation of 6-hydroxynicotinic acid to establish a new technology, a combined technology of growing culture transformation and resting cells transformation. In the combination technology, when 1% of nicotinic acid was kept in cultivation medium by supplement of nicotinic acid at intervals during cultivation of Pseudomonas putida NA-1, the growing culture could consistently hydroxylate nicotinic acid without degradation of its product which was accumulated linearly in the cultivation medium with progress of cultivation; the resting cells obtained from cultivation broth after growing culture transformation still processed a very high hydroxylation activity and could be used to next resting transformation of nicotinic acid. By using of the combined technology, the inducer was saved and the production yield of 6-hydroxynicotinic acid increased above 65%.

Nicotinic Acids↗

Ethanol extract from Artemisia vestita, a traditional Tibetan medicine, exerts anti-sepsis action through down-regulating the MAPK and NF-kappaB pathways.

Artemisia vestita Wall., a traditional Tibetan medicine, has wide clinical application for inflammatory diseases. However, its molecular mechanism of anti-inflammatory effect is poorly understood. In the present study, we investigated the anti-inflammatory activity and underlying mechanism of the ethanol extract from Artemisia vestita (AV-ext) on lipopolysaccharide (LPS)-induced sepsis. Pretreatment with AV-ext significantly decreased the levels of tumor necrosis factor-alpha (TNF-alpha) in serum and liver and lung tissues, and improved the survival of mice with experimental sepsis. AV-ext also remarkably reduced the expression levels of TNF-alpha, interleukin-1beta and cyclooxygenase-2 in LPS-stimulated RAW 264.7 macrophages and dose dependently suppressed the activation of mitogen-activated protein kinases (MAPKs), such as p38, extracellular signal-regulated kinase (ERK1/2) and c-Jun NH2-terminal kinase (JNK). Furthermore, pretreatment with AV-ext dose dependently inhibited the activation of nuclear factor-kappaB (NF-kappaB), as well as the degradation and phosphorylation of inhibitory kappaB (IkappaB) in LPS-activated RAW 264.7 macrophages. These results collectively reveal that AV-ext inhibits TNF-alpha release from macrophages by suppressing MAPK and NF-kappaB signaling pathways and suggest that AV-ext may be beneficial for the treatment of endotoxin shock or sepsis.

Animals↗

[Effectiveness of combined surgery for treating severe obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To explore the efficiency of a comprehensive surgical approach of genioglossus advancement and hyoid suspension (GAHM) plus uvulopalatopharyngoplasty (UPPP) for treating severe obstructive sleep apnea hypopnea syndrome (OSAHS) and to evaluate related factors on surgery outcomes. METHODS: Eighteen patients with severe OSAHS (apnea hypopnea index, AHI > 40/h) confirmed with polysomnography received genioglossus advancement and hyoid suspension plus uvulopalatopharyngoplasty. The obstruction in both the oropharynx and the hypopharynx were evaluated by preoperative physical examination, fiberoptic pharyngolaryngoscopy, cephalometry, and computed tomography of the upper airway. The follow up was at least 6 months postoperatively. The Wilcoxon signed rank test was used to compare the preoperative and postoperative results by SPSS 11.0 for windows. The Mann-Whitney test was used to analyze the difference between responders and nonresponders. RESULTS: The follow up time ranges from 6 to 24 months, there were statistically significance in all but body mass index (BMI) between preoperative and postoperative measurements. Mean AHI was reduced from preoperative (x +/- s, 63.8 +/- 16.3)/h to postoperative (23.6 +/- 19.5)/h, lowest mean oxygen saturation increased from 0.72 +/- 0.07 to 0.81 +/- 0.13(x +/- s). According to criterion at home, the 6-month rate of responder is 83%, if AHI <20/h and decreased by at least 50% as success, the rate of success is 67%. The age, posterior airway space (PAS) and percentage of time with oxyhemoglobin saturation below 0.90 (CT90) were (39.1 +/- 7.4) years, (8.3 +/- 0.9) mm, (18.5 +/- 10.9)% in responder, while (52.5 +/- 9.4) years, (6.8 +/- 1.3) mm, (37.7 +/- 23.6) % in nonresponder, and there are statistically significant between responder and nonresponder. CONCLUSIONS: GAHM plus UPPP is effective surgical approach for patients with severe OSAHS who suffer from oropharyngeal and hypopharyngeal obstruction. Age, PAS and CT90 were possible affective factors on surgical outcomes.

Adult↗

Arrhythmogenic action of endothelin-1(1-31) through conversion to endothelin-1(1-21).

Endothelin (ET)-1(1-21) is known to play an important role in the pathogenesis of acute ischemic arrhythmia. In the present study, we attempted to determine whether administration of ET-1(1-31) would result in arrhythmia in perfused isolated rat hearts. Forty-eight Sprague-Dawley rats weighing approximately 250-350 g were randomized into 6 groups. Heart was isolated and perfused in a Langendorff mode. The effects of ET-1(1-31) on arrhythmia, heart rate, coronary flow, and heart function were analyzed. Perfusion with 1 nM ET-1(1-31) resulted in frequent ventricular ectopic beats (VEBs) and ventricular tachycardia (VT). Overall VEB was 128.0 (approximately 66.0-1015.0), and the arrhythmia score (AS) was 2.18 +/- 0.87; both were significantly higher than those of the control group (P < 0.01). Pretreatment with perfusion of 10 nM of the ETA-receptor antagonist BQ(123) markedly attenuated the occurrence of VEB and VT induced by ET-1(1-31). AS in 10 nM BQ123 group was significantly lower than that in 1 nM ET-1(1-31) group (P < 0.01). The arrhythmia induced by 1 nM ET-1(1-31) was partially but significantly reduced by phosphoramidon (1 microM), a neutral endopeptidase/ET-converting enzyme inhibitor. ET-1(1-31) per se caused arrhythmia in perfused isolated rat hearts. This arrhythmogenic action is in part mediated by ET(A) receptor and may be attributed mainly to the conversion of ET-1(1-31) to ET-1(1-21.).

Animals↗

[Specific depletion of naringin from Si-Ni-San, a traditional Chinese prescription, by an immunoaffinity chromatography].

To specifically deplete the compound naringin from Si-Ni-San, a traditional Chinese prescription, an immunoaffinity chromatography column was prepared. The naringin bovine serum albumin (BSA) complex (naringin-BSA) was synthesized to make the complete antigen naringin-BSA. Polyclonal antibody was prepared from the serum of rabbit immunized with naringin-BSA. Then, an immunoaffinity column was made by covalently coupling the polyclonal antibody to CNBr-activated Sepharose 4B and used for depleting naringin from Si-Ni-San. The polyclonal antibody obtained from the rabbit serum was found through enzyme linked immunosorbent assay (ELISA) to show the titer of 1:30,000, the purity of 94% and low cross-reaction rate. The coupling rate of the polyclonal antibody to Sepharose 4B was 87%. By using this column, naringin in Si-Ni-San was selectively depleted from the whole extract. This immunoaffinity column of anti-naringin antibody could be used for specifically depleting naringin from Si-Ni-San and other samples.

Animals↗

[Identification of a strain NJ2 hydroxylating imidacloprid and the transformed product].

A strain named NJ2 was isolated from the soils in Nanjing area, and its resting cells transformed IMI into a polar product. The strain was identified as Stenotrophomonas maltophilia based on BioMerieux Vitek system and the analysis of 16S rDNA sequence. Mass spectrometry of the product extracted with an organic solvent and re-crystallization gave m/z value of 272 for the molecular ion while 256 for substrate IMI. It demonstrated that the transformed product was the hydroxylated derivate of IMI or hydroxy IMI. NMR analysis further indicated that the hydroxyl moiety located at the ring of imidazolidine and the transformed product was 5-hydroxy IMI. Kinetics of transformation IMI showed that the content of IMI decreased 1.15 mmol/L and the content of transformed product 5-hydroxy IMI increased 1.10 mmol/L after transformation for 10 days. The molar conversion yield was 95.9%. The S. maltophilia NJ2 strain, with the characterization of strong transformation ability and high molar conversion yield, can be used in industrial production of 5-hydroxy IMI for synthesis of highly insecticidal olefin IMI.

DNA, Ribosomal↗

[Evaluation of the relationship between IL-18 levels in urine and parameters of renal pathological changes in patients with lupus nephritis].

AIM: To evaluate the relationship between IL-18 levels in urine and parameters of renal pathological changes in patients with lupus nephritis (LN). METHODS: IL-18 levels in morning free urine and 24-hour's urine in 19 normal persons and 55 patients with LN were measured by ELISA. The correlation between IL-18 levels and parameters of renal pathological changes, namely activity index (AI) and chronicity index (CI), were analyzed by liner correlation analysis method. RESULTS: IL-18 levels in morning free urine and 24-hour's urine in LN group were elevated significantly compared with control group. In both groups IL-18 levels in morning free urine were (247.1+/-317.5) ng/L and (20.3+/-14.5) ng/L, respectively, P<0.001; those in 24-hour's urine were (192.1+/-170.1) ng/d and (21.0+/-3.8) ng/d, respectively, (P<0.001). There was close positive correlation between IL-18 levels in morning free urine and 24-hour's urine and LN patient's AI (for morning free urine: r=0.602, P<0.001; for 24-hour's urine: r=0.461, P<0.005) but there was no correlation between IL-18 levels in morning urine and 24-hour's urine and CI (P>0.05). Patients with LN were divided into three groups (high, moderate and low) according to AI value. There was distinct difference of IL-18 levels in urine among the three groups: IL-18 levels in morning urine were (69.2+/-82.7) ng/L, (193.5+/-106.1) ng/L and (580.7+/-453.1) ng/L, respectively, (P<0.001); those in 24-hour's urine were (103.5+/-141.4) ng/d, (188.8+/-124.0) ng/d and (333.1+/-183.2) ng/d, respectively. CONCLUSION: It is very simple and convenient to detect IL-18 levels in morning free urine, so it is a good method for evaluating renal pathological activity of LN.

Chronic Disease↗

Self-assembly of patchy particles into diamond structures through molecular mimicry.

Fabrication of diamond structures by self-assembly is a fundamental challenge in making three-dimensional photonic crystals. We simulate a system of model hard particles with attractive patches and show that they can self-assemble into a diamond structure from an initially disordered state. We quantify the extent to which the formation of the diamond structure can be facilitated by "seeding" the system with small diamond crystallites or by introducing a rotation interaction to mimic a carbon-carbon antibonding interaction. Our results suggest patchy particles may serve as colloidal "atoms" and "molecules" for the bottom-up self-assembly of three-dimensional crystals.

Journal Article↗

Microbial hydroxylation of imidacloprid for the synthesis of highly insecticidal olefin imidacloprid.

Microorganisms that bring about the aerobic transformation of imidacloprid (IMI) were isolated and screened, and the microbial regio- and stereoselective hydroxylation of IMI was studied. Some bacteria and fungi transformed IMI to 5-hydroxyl IMI. Bacterium Stenotrophomonas maltophilia CGMCC 1.1788 resting cells transformed IMI into R-5-hydroxyl IMI at the highest conversion rate. The enzyme catalyzed the stereoselective hydroxylation at position C12 of IMI in the imidazolidine ring. Under acidic conditions, 5-hydroxyl IMI was converted into olefin IMI in high molar conversion yield. The olefin IMI exhibited about 19 and 2.2 times more insecticidal efficacy than IMI against horsebean aphid imago and nymph, respectively, and about 1.4 times more active than IMI against brown planthopper imago. The transformation rate of IMI by resting cells of S. maltophilia CGMCC 1.1788 was promoted significantly by some carbohydrates and organic acids. The reaction medium with 5% sucrose resulted in 8.3 times greater biotransformation yield as compared with that without sucrose.

Bacteria↗

SRC tyrosine kinase and multidrug resistance protein-1 inhibitions act independently but cooperatively to restore paclitaxel sensitivity to paclitaxel-resistant ovarian cancer cells.

Src tyrosine kinase has been found to be overexpressed in both mouse and human ovarian cancer cells as well as in human primary ovarian cancers. Furthermore, Src inhibition sensitizes ovarian cancer cells to chemotherapeutic agents such as paclitaxel and cisplatin. Interestingly, Src inhibition has also been shown to resensitize paclitaxel-resistant cells to the cytotoxic effects of paclitaxel. The current study was undertaken in an effort to determine the mechanism by which Src resensitizes drug-resistant ovarian cancer cells. The paclitaxel-resistant human (CaOV3TaxR) and mouse (ID8TaxR) ovarian cancer cell lines express large amounts of the multidrug resistance-1 (MDR-1) protein compared with the paclitaxel-sensitive parent cell lines. Src inhibition had no effect on MDR-1 protein expression. Furthermore, Src inhibition did not affect MDR-1 function as determined by rhodamine 123 and paclitaxel uptake or retention. Coinhibition of both Src and MDR-1 synergistically enhanced paclitaxel-induced cytotoxicity in paclitaxel-resistant ovarian cancer cell lines. Inhibition of Src enhanced microtubule stabilization in paclitaxel-resistant ovarian cancer cells treated with paclitaxel without affecting expression of beta-tubulin isotypes and resulted in multipolar spindle formation and apoptosis. These results show that Src inhibition restores paclitaxel sensitivity to paclitaxel-resistant ovarian cancer cells by an MDR-independent mechanism, possibly by decreasing the critical intracellular concentration at which paclitaxel induces tubulin stabilization and bundling. Src tyrosine kinase may provide a viable target for therapeutic intervention in drug-resistant ovarian cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Selecting additional tag SNPs for tolerating missing data in genotyping.

BACKGROUND: Recent studies have shown that the patterns of linkage disequilibrium observed in human populations have a block-like structure, and a small subset of SNPs (called tag SNPs) is sufficient to distinguish each pair of haplotype patterns in the block. In reality, some tag SNPs may be missing, and we may fail to distinguish two distinct haplotypes due to the ambiguity caused by missing data. RESULTS: We show there exists a subset of SNPs (referred to as robust tag SNPs) which can still distinguish all distinct haplotypes even when some SNPs are missing. The problem of finding minimum robust tag SNPs is shown to be NP-hard. To find robust tag SNPs efficiently, we propose two greedy algorithms and one linear programming relaxation algorithm. The experimental results indicate that (1) the solutions found by these algorithms are quite close to the optimal solution; (2) the genotyping cost saved by using tag SNPs can be as high as 80%; and (3) genotyping additional tag SNPs for tolerating missing data is still cost-effective. CONCLUSION: Genotyping robust tag SNPs is more practical than just genotyping the minimum tag SNPs if we can not avoid the occurrence of missing data. Our theoretical analysis and experimental results show that the performance of our algorithms is not only efficient but the solution found is also close to the optimal solution.

Algorithms↗

Direct electrochemistry and electrocatalysis of heme proteins entrapped in agarose hydrogel films in room-temperature ionic liquids.

The electrochemistry and electrocatalysis of a number of heme proteins entrapped in agarose hydrogel films in the room-temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) have been investigated. UV-vis and FTIR spectroscopy show that the heme proteins retain their native structure in agarose film. The uniform distribution of hemoglobin in agarose-dimethylformamide film was demonstrated by atomic force microscopy. Cyclic voltammetry shows that direct electron transfer between the heme proteins and glassy carbon electrode is quasi-reversible in [bmim][PF(6)]. The redox potentials for hemoglobin, myoglobin, horseradish peroxidase, cytochrome c, and catalase were found to be more negative than those in aqueous solution. The charge-transfer coefficient and the apparent electron-transfer rate constant for these heme proteins in [bmim][PF(6)] were calculated from the peak-to-peak separation as a function of scan rate. The heme proteins catalyze the electroreduction of trichloroacetic acid and tert-butyl hydroperoxide in [bmim][PF(6)]. The kinetic parameter I(max) (maximum current at saturation concentration of substrate) and the apparent K(m) (Michaelis-Menten constant) for the electrocatalytic reactions were evaluated.

Biosensing Techniques↗

Reproducible preparation and effective separation of PEGylated recombinant human granulocyte colony-stimulating factor with novel "PEG-pellet" PEGylation mode and ion-exchange chromatography.

A novel preparation for polyethylene glycol (PEG) derivatives and chromatographic separation procedure of the PEGylated recombinant human granulocyte colony-stimulating factor (rhG-CSF) were designed to evaluate the reproducibility and scalability at large laboratory-scale level. The new "PEG-pellet" PEGylation mode was successfully applied to control the pH fluctuation during the conjugation reaction, a general problem in traditional liquid-phase conjugation mode. Moreover, two consecutive ion-exchange chromatography steps were successfully used to separate and purify the PEGylated rhG-CSF. Cation-exchange chromatography was firstly applied to separate PEGylated rhG-CSF from intact rhG-CSF, followed by anion-exchange chromatography to obtain individual PEG-rhG-CSF species (mono-, di- and tri-PEGylated rhG-CSF) and remove the excess free PEG. Furthermore, the molecular weight of individual PEGylated rhG-CSF was identified by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry and SDS-PAGE, and cell proliferation activity in vitro was detected by MTT assay using NFS-60 cell.

Animals↗

Induction of apoptosis in mouse liver by microcystin-LR: a combined transcriptomic, proteomic, and simulation strategy.

Microcystins (MCs) are a family of cyclic heptapeptide hepatotoxins produced by freshwater species of cyanobacteria that have been implicated in the development of liver cancer, necrosis, and even deadly intrahepatic bleeding. MC-LR, the most toxic MC variant, is also the most commonly encountered in a contaminated aquatic system. This study presents the first data in the toxicological research of MCs that combines the use of standard apoptotic assays with transcriptomics, proteomic technologies, and computer simulations. By using histochemistry, DNA fragmentation assays, and flow cytometry analysis, we determined that MC-LR causes rapid, dose-dependent apoptosis in mouse liver when BALB/c mice are treated with MC-LR for 24 h at doses of either 50, 60, or 70 microg/kg of body weight. We then used gene expression profiling to demonstrate differential expressions (>2-fold) of 61 apoptosis-related genes in cells treated with MC-LR. Further proteomic analysis identified a total of 383 proteins of which 35 proteins were up-regulated and 30 proteins were down-regulated more than 2.5-fold when compared with controls. Combining computer simulations with the transcriptomic and proteomic data, we found that low doses (50 microg/kg) of MC-LR lead to apoptosis primarily through the BID-BAX-BCL-2 pathway, whereas high doses of MC-LR (70 microg/kg) caused apoptosis via a reactive oxygen species pathway. These results indicated that MC-LR exposure can cause apoptosis in mouse liver and revealed two independent pathways playing a major regulatory role in MC-LR-induced apoptosis, thereby contributing to a better understanding of the hepatotoxicity and the tumor-promoting mechanisms of MCs.

Animals↗

Selective depletion of glycyrrhizin from Si-Ni-San, a traditional Chinese prescription, blocks its effect on contact sensitivity in mice and recovers adhesion and metalloproteinases production of T lymphocytes.

In the present study, we performed to selectively deplete glycyrrhizin from Si-Ni-San, a traditional Chinese prescription that consists of 4 Chinese herbs including Radix Glycyrrhizae Uralensis, and examined its influence on the suppressing activity of Si-Ni-San against contact sensitivity in mice. An immunoaffinity column was made by covalently coupling the polyclonal antibody, obtained by the immunization with glycyrrhizin-BSA conjugate, to CNBr-activated Sepharose 4B. By using this column, glycyrrhizin in Si-Ni-San was selectively and almost completely depleted from the whole extract, which was confirmed by high-performance liquid chromatography (HPLC). Both 200 mg/kg of Si-Ni-San and 10 mg/kg of glycyrrhizin, the dose corresponding to its proportion contained in Si-Ni-San, significantly reduced the ear swelling of picryl chloride (PCl)-induced ear contact sensitivity in mice and the inhibition by Si-Ni-San was stronger than that by glycyrrhizin. The adhesion activity to type IV collagen of the isolated spleen cells from PCl-sensitized mice was significantly decreased by both Si-Ni-San and glycyrrhizin. However, the glycyrrhizin-depleted sample of Si-Ni-San (Si-Ni-San(GL-)) only showed a slight inhibition on the cell adhesion. Furthermore, the spleen cells from PCl-sensitized mice produced more matrix metalloproteinase (MMP)-2 and -9 than naive spleen cells did, and both Si-Ni-San and glycyrrhizin remarkably reduced MMP-2 and MMP-9 production. In contrast, Si-Ni-San(GL-) only showed a slight inhibition. These results suggest that glycyrrhizin may act as one of the active constituents of Si-Ni-San in inhibiting delayed-type hypersensitivity reaction via down-regulating the MMP production and the cell adhesion to extracellular matrix. The present study also provides a new approach to recognize and validate an active constituent in traditional prescription through a selective depletion.

Animals↗

Inference of missing SNPs and information quantity measurements for haplotype blocks.

MOTIVATION: Missing data in genotyping single nucleotide polymorphism (SNP) spots are common. High-throughput genotyping methods usually have a high rate of missing data. For example, the published human chromosome 21 data by Patil et al. contains about 20% missing SNPs. Inferring missing SNPs using the haplotype block structure is promising but difficult because the haplotype block boundaries are not well defined. Here we propose a global algorithm to overcome this difficulty. RESULTS: First, we propose to use entropy as a measure of haplotype diversity. We show that the entropy measure combined with a dynamic programming algorithm produces better haplotype block partitions than other measures. Second, based on the entropy measure, we propose a two-step iterative partition-inference algorithm for the inference of missing SNPs. At the first step, we apply the dynamic programming algorithm to partition haplotypes into blocks. At the second step, we use an iterative process similar to the expectation-maximization algorithm to infer missing SNPs in each haplotype block so as to minimize the block entropy. The algorithm iterates these two steps until the total block entropy is minimized. We test our algorithm in several experimental data sets. The results show that the global approach significantly improves the accuracy of the inference. AVAILABILITY: Upon request.

Algorithms↗