Cellular senescence imaging and senolysis monitoring in cancer therapy based on a β-galactosidase-activated aggregation-induced emission luminogen

Cellular senescence is a permanent state of cell cycle arrest characterized by increased activity of senescence associated β-galactosidase (SA-β-gal). Notably, cancer cells have been also observed to exhibit the senescence response and are being considered for sequential treatment with pro-senescence therapy followed by senolytic therapy. However, there is currently no effective agent targeting β-galactosidase (β-Gal) for imaging cellular senescence and monitoring senolysis in cancer therapy. Aggregation-induced emission luminogen (AIEgen) demonstrates strong fluorescence, good photostability, and biocompatibility, making it a potential candidate for imaging cellular senescence and monitoring senolysis in cancer therapy when endowed with β-Gal-responsive capabilities. In this study, we introduced a β-Gal-activated AIEgen named QM-β-gal for cellular senescence imaging and senolysis monitoring in cancer therapy. QM-β-gal exhibited good amphiphilic properties and formed aggregates that emitted a fluorescence signal upon β-Gal activation. It showed high specificity towards the activity of β-Gal in lysosomes and successfully visualized DOX-induced senescent cancer cells with intense fluorescence both in vitro and in vivo. Encouragingly, QM-β-gal could image senescent cancer cells in vivo for over 14 days with excellent biocompatibility. Moreover, it allowed for the monitoring of senescent cancer cell clearance during senolytic therapy with ABT263. This investigation indicated the potential of the β-Gal-activated AIEgen, QM-β-gal, as an in vivo approach for imaging cellular senescence and monitoring senolysis in cancer therapy via highly specific and long-term fluorescence imaging. STATEMENT OF SIGNIFICANCE: This work reported a β-galactosidase-activated AIEgen called QM-β-gal, which effectively imaged DOX-induced senescent cancer cells both in vitro and in vivo. QM-β-gal specifically targeted the increased expression and activity of β-galactosidase in senescent cancer cells, localized within lysosomes. It was cleared rapidly before activation but maintained stability after activation in the DOX-induced senescent tumor. The AIEgen exhibited a remarkable long-term imaging capability for senescent cancer cells, lasting over 14 days and enabled monitoring of senescent cancer cell clearance through ABT263-induced apoptosis. This approach held promise for researchers seeking to achieve prolonged imaging of senescent cells in vivo.

Therapeutic potential of tumor treating fields for malignant brain tumors

BACKGROUND

Malignant brain tumors are among the most threatening diseases of the central nervous system, and despite increasingly updated treatments, the prognosis has not been improved. Tumor treating fields (TTFields) are an emerging approach in cancer treatment using intermediate-frequency and low-intensity electric field and can lead to the development of novel therapeutic options.

RECENT FINDINGS

A series of biological processes induced by TTFields to exert anti-cancer effects have been identified. Recent studies have shown that TTFields can alter the bioelectrical state of macromolecules and organelles involved in cancer biology. Massive alterations in cancer cell proteomics and transcriptomics caused by TTFields were related to cell biological processes as well as multiple organelle structures and activities. This review addresses the mechanisms of TTFields and recent advances in the application of TTFields therapy in malignant brain tumors, especially in glioblastoma (GBM).

CONCLUSIONS

As a novel therapeutic strategy, TTFields have shown promising results in many clinical trials, especially in GBM, and continue to evolve. A growing number of patients with malignant brain tumors are being enrolled in ongoing clinical studies demonstrating that TTFields-based combination therapies can improve treatment outcomes.

Visualization of Mitochondria During Embryogenesis in Zebrafish by Aggregation-Induced Emission Molecules

PURPOSE

Aggregation-induced emission (AIE) molecules have been widely utilized for fluorescence imaging in many biomedical applications, benefited from large Stokes shift, high quantum yield, good biocompatibility, and resistance to photobleaching. And visualization of mitochondria is almost investigated in vitro and ex vivo, but in vivo study of mitochondria is more essential for systematic biological research, especially during embryogenesis. Therefore, suitable and time-saving alternatives with simple operation based on AIE molecules are urgently needed compared with traditional transgenic approach.

PROCEDURES

Five tetraphenylethylene isoquinolinium (TPE-IQ)-based molecules with AIE characteristics and their ability of mitochondrial visualization in vitro and in vivo and mitochondrial tracking during embryogenesis on zebrafish model were investigated. The biosafety of these AIE molecules was also evaluated systematically in vitro and in vivo.

RESULTS

All these five AIE molecules could image mitochondria in vitro with good biocompatibility. In them, TPE-IQ1 exhibited excellent imaging quality for in vivo visualization and tracking of mitochondria during the 4-day embryogenesis in zebrafish, in comparison with the conventional transgenic fluorescent protein. Furthermore, TPE-IQ1 could visualize mitochondrial damage induced by chemicals in real time on 24-h post fertilization (hpf) embryos.

CONCLUSIONS

This study indicated TPE-IQ-based AIE molecules had the potential for mitochondrial imaging and tracking during embryogenesis and mitochondrial damage visualization in vivo.

Evaluation of medical services from the perspective of COVID-19 vaccine demand satisfaction in Hangzhou, China

The outbreak of COVID-19 has had a huge global impact, and it continues to test the resilience of medical services to emergencies worldwide. In the current post-epidemic era, vaccination has become a highly effective strategy to prevent the spread of COVID-19. However, using conventional mathematical models to evaluate the spatial distribution of medical resources, including vaccination, ignore people's behaviors and choices and make simplifications to the real world. In this study, we use an enhanced model based on the Theory of People Behavior (TPB) to perform a macro analysis of the satisfaction ability of medical resources for vaccination in Hangzhou, China, and attribute the city to a three-level structure. According to the allocation, the supply capacity of vaccination sites is calculated and divided into four categories (good, normal, not bad, and bad). Meanwhile, we raise an assumption based on the result and the general development law of the city and analyze the reasons for the impact of personal behavior on the spatial distribution of medical resources, as well as the relationship between the demand distribution and spatial distribution of medical resources and future development strategies. It is considered that the overall medical resources, especially vaccination in Hangzhou, feature the situation of central supply overflow, and are found to hardly meet the needs of population points in surrounding areas, requiring a more flexible strategy to allocate facilities in these areas.

Highly efficient radiosynthesis and biological evaluation of [18F]safinamide, a radiolabelled anti-parkinsonian drug for PET imaging

As an add-on drug approved for Parkinson's disease treatment, safinamide has multiple functions, such as selective and reversible monoamine oxidase-B inhibition, voltage-sensitive sodium/potassium channel blockage, and glutamate release inhibition. Meanwhile, safinamide shows tremendous therapeutic potential in the context of other central nervous system diseases (e.g., ischaemic stroke, amyotrophic lateral sclerosis, depression, etc.).  In this work, [18F]safinamide, which is safinamide labelled by the positron-emitting radionuclide [18F]fluorine, was synthesized automatically based on iodonium ylide precursors with high radiochemical yield and high molar activity. Density functional theory was applied to calculate the Gibbs free energy change during iodonium ylide-mediated fluorination and to interpret the effect of tetraethylammonium (TEA+) as the counter cation in these reactions to improve the nucleophilicity of [18F/19F]fluoride. In addition, positron emission tomography studies on Sprague Dawley rats were carried out to determine the imaging characteristics, pharmacokinetics, and metabolism of the [18F]safinamide radiotracer. The results displayed the complete biodistribution of the radiotracer, especially in rat brains, and revealed that [18F]safinamide has moderate brain uptake, rapid and reversible binding kinetics, and good stability.

Gene profile identifies zinc transporters differentially expressed in normal human organs and human pancreatic cancer

Deregulated expression of zinc transporters was linked to several cancers. However, the detailed expression profile of all human zinc transporters in normal human organs and in human cancer, especially in pancreatic cancer is not available. The objectives of this study are to investigate the complete expression patterns of 14 ZIP and 10 ZnT transporters in a large number of normal human organs and in human pancreatic cancer tissues and cell lines. We examined the expression patterns of ZIP and ZnT transporters in 22 different human organs and tissues, 11 pairs of clinical human pancreatic cancer specimens and surrounding normal/benign tissues, as well as 10 established human pancreatic cancer cell lines plus normal human pancreatic ductal epithelium (HPDE) cells, using real time RT-PCR and immunohistochemistry. The results indicate that human zinc transporters have tissue specific expression patterns, and may play different roles in different organs or tissues. Almost all the ZIPs except for ZIP4, and most ZnTs were down-regulated in human pancreatic cancer tissues compared to the surrounding benign tissues. The expression patterns of individual ZIPs and ZnTs are similar among different pancreatic cancer lines. Those results and our previous studies suggest that ZIP4 is the only zinc transporter that is significantly up-regulated in human pancreatic cancer and might be the major zinc transporter that plays an important role in pancreatic cancer growth. ZIP4 might serve as a novel molecular target for pancreatic cancer diagnosis and therapy.

MicroRNA-34b inhibits pancreatic cancer metastasis through repressing Smad3

Pancreatic cancer is characterized by extremely poor prognosis because of early recurrence and metastasis, and increasing evidence supports the critical role of microRNA in cancer progression. Here we identified that microRNA-34b functioned as a tumor-suppressing microRNA by targeting oncogenic Smad3 in pancreatic cancer. As a hypovascular tumor with a potential endoplasmic reticulum stress microenvironment, miR-34b was silenced after ER stress inducer thapsigargin (Tg) treatment and negatively regulated by ER stress chaperone glucose regulated protein 78 (GRP78) in pancreatic cancer cells. In human specimens, we found that miR-34b was down-regulated in pancreatic cancer tissues and low level of miR-34b expression was positively correlated with tumor-node-metastasis (TNM) stage, lymph-node metastasis and overall survival. Functional assays showed that over-expression of miR-34b inhibited pancreatic cancer progression in vitro and in vivo. In addition, Smad3 was demonstrated as a direct target of miR-34b and negatively regulated by miR- 34b at mRNA and protein levels. Luciferase assays confirmed that miR-34b could directly bind to the 3'untranslated region of Smad3. An inverse correlation between miR-34b and Smad3 was observed in 64 pancreatic cancer tissues. Our findings indicate that miR-34b acts as a tumor metastasis suppressor through negatively modulating Smad3, which may provide a potential therapeutic strategy for pancreatic cancer.

Population-based analysis of multimodality treatment of gastric cancer

124

Background: Limited data is available for the role of multimodality management for gastric adenocarcinoma and its outcome in the community.

Methods: We retrospectively reviewed the outcomes for 341 patients (pts) who were diagnosed with gastric cancer in a community-based health-care system, including 9 hospitals, from 2000 to 2009.

Results: 148/341 pts had undergone surgery and were included in the analysis. Median age at diagnosis was 68 year (range: 32-96), 56% were male, 55% were Caucasian and 25% were black. The stage distribution was as follows: 27% (40 pts) localized, 61% (90 pts) locally advanced and 12% (18 pts) with distant metastasis. 98 pts (66%) received surgery alone, 22 pts (15%) received perioperative chemotherapy, and 28 pts (19%) received perioperative chemo-radiation. After a median follow-up time of 5.2 yrs, the median OS for the entire group was 1.9 years, and 88 deaths had occurred at the last follow up. By stage, the median OS was 7 yrs, 2.3 yrs, and 0.3 yrs for localized stage, regional stage, and metastatic disease, respectively. The 5-yr survival was significantly better in pts who received perioperative chemo-radiation (68%), compared to those who received with surgery alone (33%) or perioperative chemotherapy (0%) (p=0.002). The 5-yr survivals by stage and treatment are shown in the table.

Conclusions: Perioperative chemo-radiation was associated with a significantly better OS compared to surgery alone. Trimodality therapy for gastric cancer appears to be underutilized in the community setting described here. The survival advantage of surgery plus chemoradiation compared to surgery plus chemotherapy remains controversial and should be investigated in clinical trials.

[Table: see text]

No significant financial relationships to disclose.

Radioembolization of unresectable primary and secondary hepatic malignancies using yttrium-90: The University of Texas at Houston experience

311

Background: Few effective treatments exist for unresectable hepatic malignant lesions. The objective of this study was to analyze the patient outcomes and toxicities of yttrium-90 (Y90) radioembolization in patients with unresectable primary and secondary hepatic malignancies.

Methods: A retrospective review from 3/03 to11/09 of pts with liver malignancies who received Y-90 (TheraSphere and SIR-Spheres) was conducted. Pretreatment CT scans characterized the liver lesions. Hepatic arterial Tc-99m MAA scans showed % lung shunt and liver flow. Postprocedure toxicities (including pt symptoms, lab values) were recorded. CT/MRI scans at 1-, 3-, and 6-month intervals measured tumor response as per RECIST 1.0. The Kaplan-Meier method was used for survival analyses.

Results: 50 pts were initially screened, of which 44 pts received 63 Y90 treatments. Mean age was 62y (24 male, 20 female). Of the 44 pts, 15 had hepatocellular cancer (HCC), 2 had intrahepatic cholangiocarcinoma and 27 had liver metastases (10 colorectal, 8 breast, 4 carcinoid, 1 esophagus, 1 lung, 1 gallbladder, 1 pancreas, 1 gastric). Mean tumor size was 10.6 cm (range 2.2-23.5cm), mean tumor absorbed dose was 30.8 mCi (range 7.1-63.5 mCi). Post-procedure symptoms included fatigue (n=21, 47.7%), abdominal pain (n=35, 79.5%), nausea/vomiting (n=12, 27.2%). At 1 month, 20 pts (45.5%) had SD, 14 (31.8%) had PR, and 10 (22.7%) had PD. At 3 months, 25 patients had SD, 10 had PD and 9 pts were in hospice or were deceased. At 6 months, 11 pts had SD. Per RECIST, PD at 1, 3, 6- months were significant predictors of mortality (OR 25, p<0.0002) as was the preprocedure MELD (OR 1.208, p=0.0160). Caucasian pts had a lower overall mortality (OR 1.238, p=0.0363). Survival analyses will be updated. One pt with HCC was successfully downstaged after Y90 and listed for liver transplant; 26 patients were alive at 6-month follow-up.

Conclusions: Y90 radioembolization represents a pragmatic option for hepatic lesions malignancies not amenable to resection. With an acceptable safety profile and the promising response on imaging, Y90 warrants further trials into its ideal use in the therapeutic algorithm for unresectable liver lesions.

No significant financial relationships to disclose.

A phase I study of everolimus plus sorafenib in patients with metastatic renal cell carcinoma (mRCC)

e16056

Background: Everolimus, a mTOR inhibitor and Sorafenib, a Raf kinase inhibitor had shown their efficacy in RCC, as single agents. Combining these two active agents could have potential additive or synergistic effects. We conducted a phase I study to evaluate the maximum tolerated dose (MTD) of this combination in patients with progressive mRCC. Methods: Patients predominantly had clear cell RCC, and progressive measurable diseases on prior treatments including immunotherapy, TKI and/or Everolimus. Patients were evaluated weekly for toxicities and every 8 weeks for radiological response, including at least both PET/CT and CT scans at baseline and 1st staging. Patients received daily Everolimus and twice daily sorafenib both orally at escalating dose levels of 2.5mg/400mg (dose level 0), 5mg/400mg (+1), and 10mg/400mg (+2). Results: 18 patients with mRCC were enrolled and 15 patients were evaluable. 6 patients were treated on dose level 0, dose- limited toxicity (DLT) was found in 2/6 patients, one with thrombocytopenia/leukopenia, the other with pneumonitis; 6 patients were treated on dose level +1, DLT of pulmonary embolism was found in 1/6 patient; and 3 patients were treated on dose level +2, without DLT. The most common side effect was grade 1/2 hand-foot syndrome (4/15, 27%). The MTD was dose level +2. Overall response by RECIST was 27% (4/15 patients): pathological complete response (CR) was 6% (1/15); radiographic CR was 6% (1/5); surgical CR after resection was 6% (1/15). 47% (7/15) of the patients had stable disease. Decreased FDG uptake was found in 67% (10/15) of the patients. The median PFS was 5.53 months (range, 1.4–14.7), and OS was 7.9 months (range, 2.3–23). Conclusions: The MTD of combining daily Everolimus 10mg and twice daily sorafenib 400mg are safe and effective for progressive metastatic RCC. The phase II trial is planned to start in early 2009.

[Table: see text]

Granulocyte macrophage: Colony stimulating factor (GM-CSF), ketoconazole, and mitoxantrone as second-line therapy in patients (Pts) with progressive hormone refractory prostate cancer (HRPC)

e16033

Background: A variety of docetaxel regimens have been tested in HRPC pts, yielding response rates between 38% - 69%. Docetaxel therapy has been widely used as first line therapy. Second line therapies, which are non - taxane based with comparable activities do not exist. This trial is built on the significant body of work which has demonstrated anti-tumor activity of GM-CSF, Ketoconazole and Mitoxantrone alone and in combination in pts with HRPC. The trial is designed to assess the combination of all three agents. Methods: No more than two prior chemotherapy regimens (one which contained docetaxel), progressive disease, and adequate marrow / organ function. Treatment consisted of: Ketoconazole daily 400mg po tid, GM-CSF subcutaneous 250mcg / m2 (14 days on/ 7 days off) and Mitoxantrone 12mg / m2 every 3 weeks (maximum cumulative dose of 140mg / m2), until either the completion of Mitoxantrone or maximum anti-tumor benefit. Pts continued Ketoconazole/ GM-CSF until disease progression. PSA was evaluated every 3 weeks and radiographic studies were performed every 9 weeks. Results: 31 pts were enrolled; 4 pts with PSA only, 9 bone only, 5 soft tissue only, and 13 bone and soft tissue. 2 pts withdrew from study due to toxicity. 8 pts had a PSA response of ≥ 50%, 5 pts had a PSA response of ≥ 80%, and 7 pts had a PSA response of ≥ 90%. 9 pts progressed. The majority of pts had stabilization of their bone and soft tissue involvement and 2 pts with nodal involvement demonstrated a radiographic CR. Significant adverse events included grade III/IV neutropenia, thrombocytopenia, and nausea. Median duration of treatment was 6.22 months (range 2 months - 20.5 months). Conclusions: GM-CSF, Ketoconazole and Mitoxantrone in combination demonstrate significant anti-tumor activity and reversible toxicity in pts who have failed prior docetaxel therapy. Information regarding PSA response, radiographic outcome and adverse event data will be presented. This data warrants further investigation such as a randomized phase II study.

[Table: see text]

Vaccination of renal cell cancer (RCC) patients with modified vaccinia Ankara (MVA) delivering tumor antigen 5T4 administered alone or with interleukin 2 (IL-2) or interferon-alpha (IFN)

3026

Background: The attenuated vaccinia virus (MVA) has been engineered to deliver the tumor antigen 5T4 (TroVax). More than 90% of RCCs overexpress the 5T4 antigen. A series of clinical trials were conducted to evaluate the effectiveness of MVA 5T4 as a single agent or in combination with either IL-2 or IFN. Methods: Eligibility: Pathologic diagnosis of clear cell or papillary RCC, progressive measurable metastases, any prior therapy, adequate physiological parameters, Karnofsky performance status ≥ 80%, and no active CNS involvement. A regimen of MVA 5T4 alone or in combination with IL-2 or IFN was given. Results: A total of 53 pts received MVA 5T4 alone or in combination with IL-2 or IFN. 13 pts received MVA 5T4 alone, 25 pts received low dose subcutaneous IL-2, and 15 pts received IFN. Clinical responses were assessed by measuring changes in tumor burden via computed tomography or magnetic resonance imaging scan. 5T4-specific cellular and humoral responses were monitored throughout the study. 5T4 was well tolerated with no serious adverse events attributed to vaccination. Of 48 intention-to-treat pts, 43 mounted 5T4-specific antibody responses. 2 pts showed a complete response for > 36 months and 2 other pts had a partial response for > 24 months and 12 months respectively. 20 pts demonstrated disease stabilization for ≥ 3 months. Median progression-free survival and overall survival for all pts was 3.6 months (range 0.8–29.7) and 13.2 months (range 1–38) respectively. A significant relationship was detected between the magnitude of 5T4-specific antibody response and overall survival. Conclusions: 5T4, whether administered alone or in combination, was well tolerated. High frequency of 5T4-specific immune responses and associated enhanced patient survival is encouraging and warrants further investigation.

[Table: see text]

Adenocarcinoma of the lower esophagus with Barrett's esophagus or without Barrett's esophagus: differences in patients' survival after preoperative chemoradiation

It remains unclear whether the overall survival (OS) of patients with localized esophageal adenocarcinoma (LEA) with Barrett's esophagus (BE) (Barrett's-positive) and those with LEA without BE (Barrett's-negative) following preoperative chemoradiation is different. Based on the published differences in the molecular biology of the two entities, we hypothesized that the two groups will have a different clinical biology (and OS). In this retrospective analysis, all patients with LEA had surgery following preoperative chemoradiation. Apart from age, gender, baseline clinical stage, location, class of cytotoxics, post-therapy stage, and OS, LEAs were divided up into Barrett's-positive and Barrett's-negative groups based on histologic documentation of BE. The Kaplan-Meier and Cox regression analytic methods were used. We analyzed 362 patients with LEA (137 Barrett's-positive and 225 Barrett's-negative). A higher proportion of Barrett's-positive patients had (EUS)T2 cancers (27%) than those with Barrett's-negative cancer (17%). More Barrett's-negative LEAs involved gastroesophageal junction than Barrett's-positive ones (P = 0.001). The OS was significantly shorter for Barrett's-positive patients than that for Barrett's-negative patients (32 months vs. 51 months; P = 0.04). In a multivariate analysis for OS, Barrett's-positive LEA (P = 0.006), old age (P = 0.016), baseline positive nodes (P = 0.005), more than 2 positive (yp)N (P = 0.0001), higher (yp)T (P = 0.003), and the use of a taxane (0.04) were the independent prognosticators. Our data demonstrate that the clinical biology (reflected in OS) is less favorable for patients with Barrett's-positive LEA than for patients with Barrett's-negative LEA. Our intriguing findings need confirmation followed by in-depth molecular study to explain these differences.

[L-lactic acid fermentation by immobilized Rhizopus oryzae in a three-phase fluidized-bed]

L-lactic acid fermentation in a three-phase fluidized-bed bioreactor was studied by using immobilized Rhizopus oryzae cells with polyurethane particles as supporter. The results indicated that the immobilized cells were stable after used for 8 batches repeatedly. The rate and the yield of lactic acid fermentation with glucose as carbon source were 19.1 g h-1.L (bead)-1 and 82.5%, respectively. With the hydrolyzate of corn cob residue from xylose manufacturer by cellulase hydrolysis, the yield of lactic acid reached 71.9%.

[Saccharification of corn stover by immobilized Trichoderma reesei cells]

The mycelia of Trichoderma reesei Rut C30 were adsorbed and immobilized within the porous polyurethane supporter. It was found that the synthesis of cellulase by the immobilized cells and the enzymatic hydrolysis of corn stover were able to be carried out in a nitrogen source-limiting medium. Under repeated batch processes with 60 g/L corn stover pretreated by 2% NaOH at 85 degrees C, the average cellulase activity (FPA) was 0.70 IU/ml, the concentration and yield of the reducing sugar were 26.41 g/L and 89.11% respectively after shaking culture at 150 r/min, 30 degrees C, pH 4.8 for 108 h. Total of 12 repeated batches were performed in 54 days. The immobilized cells kept the weight around 10 g/L. The fed-batch process was also studied with the same immobilized cells. Total of 120 g/L corn stover was added in different feeding manners. The reducing sugar of 52.8 g/L was produced after 7 days and the saccharification efficiency (89.2%) was almost the same as the batch process. The results indicated that the cellulase production and cellulosic material saccharification in situs by the immobilized Trichoderma reesei cells is an convenient and effective process for conversion and utilization of renewable biomass.

Extractive L-lactic acid fermentation with immobilized Rhizopus oryzae in a three-phase fluidized bed

The Rhizopus oryzae was immobilized by the calcium alginate entrapment method. A three-phase fluidized-bed bioreactor was designed to perform the immobilized-cell L-lactic acid fermentation. A solvent extraction column was coupled with the bioreactor to remove L-lactic acid from the fermentation broth. The TRPO was selected as solvent and sulfonated kerosene as diluent. The results indicated that the pH value in the broth was regulated above pH 3.5 and the fermentation rate was as high as 11 g L-lactic acid per hour per liter of beads. A mathematical model was proposed to describe the concentration of L-lactic acid in the extractive fermentation.

Kinetics of simultaneous saccharification and lactic acid fermentation processes

After pretreatment of corn cob by dilute acid, the lignocellulosic residue was used as raw materials for the simultaneous saccharification and lactic acid fermentation (SSLF). Because of the same optimal temperature and pH requirement as well as the anaerobic condition, the lactic acid fermentation is perfectly compatible with enzymatic hydrolysis of cellulosic materials. In the SSLF processes, the final concentration of lactic acid reached 33.97 g/L with a conversion ratio of 79% based on the consumed cellulose. A mathematical model is suggested to simulate the SSLF process with good agreement.

[Studies on the induction of L-phenylalanine ammonia lyase(PAL) in Rhodotorula glutinis and transformation of phenylalanine from trans-cinnamic acid]

The induction of PAL in Rhodotorula glutinis and transformation of L-phenylalanine from trans-cinnamic acid were studied. The optimum medium for PAL induction was composed of (g/L) 10.0 yeast extract, 10.0 peptone, 5.0 NaCl, 0.5 KH2 PO4, 0.5 phenylalanine 1.0 (NH4)2SO4 and 5.0 glucose, pH 6.0-6.5. The cultivation temperature was 30.0 degrees C. In the process of transformation, the effect of [NH4]+ on initial velocity was in accordance with Michaelis-Menten rate expression in which Km and Vmax were 16.85 mol/L and 5.96 g.L-1.h-1 for ammonia and the optimum pH was 10.0. Substrate activation and inhibition were observed at low and high concentration of cinnamic acid. The yield of phenylalanine from cinnamic acid reached more than 60.0%.