Enzyme-Directed and Organelle-Specific Sphere-to-Fiber Nanotransformation Enhances Photodynamic Therapy in Cancer Cells

Employing responsive nanoplatforms as carriers for photosensitizers represents an effective strategy to overcome the challenges associated with photodynamic therapy (PDT), including poor solubility, low bioavailability, and high systemic toxicity. Drawing inspiration from the morphology transitions in biological systems, a general approach to enhance PDT that utilizes enzyme-responsive nanoplatforms is developed. The transformation of phosphopeptide/photosensitizer co-assembled nanoparticles is first demonstrated into nanofibers when exposed to cytoplasmic enzyme alkaline phosphatase. This transition is primarily driven by alkaline phosphatase-induced changes of the nanoparticles in the hydrophilic and hydrophobic balance, and intermolecular electrostatic interactions within the nanoparticles. The resulting nanofibers exhibit improved ability of generating reactive oxygen species (ROS), intracellular accumulation, and retention in cancer cells. Furthermore, the enzyme-responsive nanoplatform is expanded to selectively target mitochondria by mitochondria-specific enzyme sirtuin 5 (SIRT5). Under the catalysis of SIRT5, the succinylated peptide/photosensitizer co-assembled nanoparticles can be transformed into nanofibers specifically within the mitochondria. The resulting nanofibers exhibit excellent capability of modulating mitochondrial activity, enhanced ROS formation, and significant anticancer efficacy via PDT. Consequently, the enzyme-instructed in situ fibrillar transformation of peptide/photosensitizers co-assembled nanoparticles provides an efficient pathway to address the challenges associated with photosensitizers. It is envisaged that this approach will further expand the toolbox for enzyme-responsive biomaterials for cancer therapy.

HDAC6-Activatable Multifunctional Near-Infrared Probe for Glioma Cell Detection and Elimination

Glioblastoma multiforme (GBM) is a highly aggressive primary brain tumor associated with limited treatment options and high drug resistance, presenting significant challenges in the pursuit of effective treatment strategies. Epigenetic modifications have emerged as promising diagnostic biomarkers and therapeutic targets for GBM. For instance, histone deacetylase 6 (HDAC6) has been identified as a potential pharmacological target for GBM. Furthermore, the overexpression of monoamine oxidase A (MAO A) in glioma has been linked to tumor progression, making it an attractive target for therapy. In this study, we successfully engineered HDAC-MB, an activatable multifunctional small-molecule probe with the goal of efficiently detecting and killing glioma cells. HDAC-MB can be selectively activated by HDAC6, leading to the "turn on" of near-infrared fluorescence and effective inhibition of MAO A, along with potent photodynamic therapy (PDT) effects. Consequently, HDAC-MB not only enables the imaging of HDAC6 in live glioma cells but also exhibits the synergistic effect of MAO A inhibition and PDT, effectively inhibiting glioma invasion and inducing cellular apoptosis. The distinctive combination of features displayed by HDAC-MB positions it as a versatile and highly effective tool for the accurate diagnosis and treatment of glioma cells. This opens up opportunities to enhance therapy outcomes and explore future applications in glioma theranostics.

Rational Design of Self-Reporting Photosensitizers for Cell Membrane-Targeted Photodynamic Therapy

Organelle-targeted photosensitizers (PSs) have demonstrated enhanced phototherapeutic effect by specifically destroying subcellular organelle. As a critical cellular organelle, the cell membrane plays crucial roles in maintaining cell integrity and regulating cellular communications. To date, a variety of membrane-targeted PSs have been developed and shown exceptional therapeutic effects. However, functional PSs that can achieve membrane-targeted photodynamic therapy (PDT) and real-time monitor the therapeutic process have rarely been reported. In particular, the development of self-reporting PS with near-infrared (NIR) absorption is highly desirable but remains a challenge. Herein, we presented two molecular rotor-based self-reporting PSs. One of the PSs, MRMP-2, possesses NIR absorption property, making it a promising candidate for clinical applications. These PSs could not only enable membrane-targeted PDT but also demonstrate selective fluorescence response toward viscosity. In this regard, the fluorescence variation of these PSs could be utilized to indicate the disruption of membrane structure during PDT process. By leveraging the feedback of the fluorescence signal, we could make intuitive judgement about the phototherapeutic results. As a result, these two PSs possess significant potential in the field of imaging-guided PDT.

Smart "Thrombus": Self-Localizing UCST-Type Microcage

Embolization is often used to block blood supply for controlling the growth of fibroids and malignant tumors, but limited by embolic agents lacking spontaneous targeting and post-treatment removal. So we first adopted nonionic poly(acrylamide-co-acrylonitrile) with an upper critical solution temperature (UCST) to build up self-localizing microcages by inverse emulsification. The results showed that these UCST-type microcages behaved with the appropriate phase-transition threshold value around 40 °C, and spontaneously underwent an expansion-fusion-fission cycle under the stimulus of mild temperature hyperthermia. Given the simultaneous local release of cargoes, this simple but smart microcage is expected to act as a multifunctional embolic agent for tumorous starving therapy, tumor chemotherapy, and imaging.

De Novo Designed Self-Assembling Rhodamine Probe for Real-Time, Long-Term and Quantitative Live-Cell Nanoscopy

Super-resolution imaging provides a powerful approach to image dynamic biomolecule events at nanoscale resolution. An ingenious method involving tuning intramolecular spirocyclization in rhodamine offers an appealing strategy to design cell-permeable fluorogenic probes for super-resolution imaging. Nevertheless, precise control of rhodamine spirocyclization presents a significant challenge. Through detailed study of the structure-activity relationship, we identified that multiple key factors control rhodamime spirocyclization. The findings provide opportunities to create fluorogenic probes with tailored properties. On the basis of our findings, we constructed self-assembling rhodamine probes for no-wash live-cell confocal and super-resolution imaging. The designed self-assembling probe Rho-2CF3 specifically labeled its target proteins and displayed high ring-opening ability, fast labeling kinetics (<1 min), and large turn-on fold (>80 folds), which is very difficult to be realized by the existing methods. Using the probe, we achieved high-contrast super-resolution imaging of nuclei and mitochondria with a spatial resolution of up to 42 nm. The probe also showed excellent photostability and proved ideal for real-time and long-term tracking of mitochondrial fission and fusion events with high spatiotemporal resolution. Furthermore, Rho-2CF3 could resolve the ultrastructure of mitochondrial cristae and quantify their morphological changes under drug treatment at nanoscale. Our strategy thus demonstrates its usefulness in designing self-assembling probes for super-resolution imaging.

Synergistic effect of oxygen vacancies and Ni particles over ZnWO4/CdS heterostructure for enhancing photocatalytic reduction and oxidation activities

Optimization of charge transfer pathway is of great significance in a capable photocatalytic system with heterostructure for the excellent reducibility and oxidizability. Here we synthesize a well-built photocatalysts of oxygen...

A NIR molecular rotor photosensitizer for efficient PDT and synchronous mitochondrial viscosity imaging

Herein, two mitochondria-targeting photosensitizers (PSs, CCVJ-Mito-1 and CCVJ-Mito-2) that exhibit a turn-on fluorescence response towards increasing viscosity are reported. Notably, CCVJ-Mito-2 exhibits absorption in the near-infrared (NIR) region, and can be employed as a NIR PS targeting mitochondria and a fluorescent probe for tracking mitochondrial viscosity changes during photodynamic therapy (PDT). This dual functional PS can help to shed light on the dynamic changes of the cellular microenvironment during PDT and further guide the PDT process.

A258 ROSAI-DORFMAN0-DESTOMBES DISEASE: A RARE CAUSE OF OBSTRUCTIVE JAUNDICE

Background

Rosai-Dorfman-Destombes Disease (RDD) is rare histiocytic disorder that is most frequently seen in children and young adults. Gastrointestinal involvement is reported in <1% of cases and typically involves the small bowel and colon. Pancreatic and hepatic involvement has been previously reported but is extremely rare.

Aims

To describe a case of obstructive jaundice in the setting of a very rare histiocytic disorder known as RDD.

Methods

Case Report

Results

A 59-year old previously healthy male of Asian descent presented with obstructive jaundice. Initial imaging demonstrated intra and extrahepatic biliary duct dilation with concurrent diffuse enlargement of the pancreas compatible with autoimmune pancreatitis. Endoscopic retrograde cholangiopancreatography (ERCP) was performed with stenting and biopsy. ERCP demonstrated a distal common bile duct stricture with biopsies suggestive of low grade reactive changes and inflammation. Subsequent endoscopic ultrasound (EUS) guided biopsy of the pancreas showed active and chronic inflammation, necrosis, and atrophic pancreatic tissue, with no definitive evidence of autoimmune pancreatitis (Figure 1). Ca-19-9 and IgG4 were normal. He was treated with a course of prednisone and responded well, with repeat CT imaging showing almost complete resolution of the previously demonstrated pancreatic changes. A diagnosis of autoimmune pancreatitis was made. He re-presented 6-months later, however, with fatigue and repeat imaging now displayed lymphadenopathy in the neck, chest, and abdomen, and a bulky pancreatic head with associated hepatomegaly. Lymph node excisional biopsy confirmed the diagnosis of RDD with the presence of scattered histiocytic cells showing emperipolesis with a low number of IgG4 positive cells (Figure 1). The patient was promptly initiated on prednisone and rituximab and has since then had excellent clinical response.

Conclusions

RDD is a rare non-Langerhans cell histiocytosis of unknown etiology that has a prevalence of 1:200 000. RDD clinically presents with painless bilateral cervical lymphadenopathy and can manifest with both nodal and extra nodal involvement. The most common sites of extra nodal disease are the skin and central nervous system, but rarely, can also present with pancreatic involvement. The use of fine needle guided biopsy in diagnosing RDD with extra nodal disease can be limited by low yield, sclerotic tissue, or non-diagnostic findings. For this reason, RDD with pancreatic involvement can masquerade as autoimmune pancreatitis, pancreatic malignancy and IgG4-related disease.This case report raises awareness about RDD with pancreatic and biliary involvement, a rare entity, that can present with obstructive jaundice.

Figure 1: Histological sections of lymph node(left) with hystiocytic cells showing emperipolesis(arrow) and pancreas(right) showing active and chronic inflamation, necrosis and atrophy

Funding Agencies

None

A113 ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY IN PATIENTS WITH SURGICALLY ALTERED ANATOMY IN A CANADIAN TERTIARY REFERRAL CENTRE

Background

Endoscopic retrograde cholangiopancreatography (ERCP) has become a mainstay of diagnosis and treatment of pancreatobiliary conditions. Surgically altered anatomy presents unique challenges in the procedure, necessitating creative solutions such as different types of endoscopes and tools. Distinct from regular anatomy, forward viewing scopes are often required for successful cannulation and therapy of the pancreaticobiliary system. To our knowledge, there is limited data on the practice of ERCP in altered anatomy in Canada.

Aims

Our aim is to present outcomes from a large series of patients with surgically altered anatomy who underwent ERCP at a large Canadian referral centre.

Methods

All ERCP procedures at a tertiary referral centre in Vancouver, Canada from Oct 2020 to Oct 2021 were reviewed retrospectively. Inclusion criteria required surgically altered anatomy and attempted ERCP. Liver transplant patients with duct-to-duct anastomosis were not included in the series. Patients with incomplete procedure documentation were excluded. Demographic, procedural and outcome data were collected. Results are presented descriptively and as median + IQR for quantitative data. Procedural success was defined as cannulation and performance of a cholangiogram and/or pancreatogram

Results

A total of 34 procedures met the inclusion criteria during the study period. Twenty-four procedures were on male patients (71%). Nineteen patients (56%) had had previous ERCP. Sixteen patients (47%) had choledocholithasis as the indication for the procedure, 9 patients (26%) had cholangitis and 5 patients (15%) had concerns of neoplasia. Some patients had multiple indications. Seventeen patients (50%) had roux-en-Y anatomy, 8 patients (24%) were post Whipple’s and 6 patients (18%) had Billroth II type anatomy. Other altered anatomy included duodenal switch, and post gastrojejunostomy bypass. The most commonly used endoscope was the adult or pediatric colonoscope (74% of cases). Single balloon enteroscope was used in 5 cases (15%). Overall success rate was 74%. The breakdown of success rate by anatomy is shown in Table 1. One (3%) complication was noted in the form of mild cholangitis, requiring only outpatient antibiotics.

Conclusions

Experience in ERCP in patients with altered anatomy is becoming more pertinent in tertiary care. Cannulation and therapy is more difficult in this cohort, but still successful in the majority of cases. Adverse events remain uncommon. Knowledge of forward viewing ERCP techniques is critical in surgically altered anatomy. Future studies will aim to expand the retrospective cohort for more quantitative analysis.

Funding Agencies

None

A125 SNARE TIP SPRAY COAGULATION FOR NON-CONTACT HEMOSTASIS: A SINGLE OPERATOR RETROSPECTIVE STUDY OF CLINICAL OUTCOMES

Background

An emerging non-contact endoscopic method for hemostasis is the use of spray coagulation (SC) using a polypectomy snare tip. Other non-contact options, such as argon plasma coagulation (APC), can be inconvenient and costly. Our current practice includes using SC where APC would be traditionally indicated.

Aims

The aim of this study was to characterize the clinical outcomes, including rates of successful hemostasis, rebleeding, and complications, for snare tip SC in hemostasis.

Methods

We conducted a retrospective chart review of all patients who underwent therapeutic endoscopy for hemostasis using snare tip SC by a single operator at a large Canadian tertiary care centre between January 2018 and September 2020.

Results

14 patients, including 10 males and 4 females, were included. 5 (35%) patients received SC during an EGD, 5 (35%) patients during a colonoscopy, and 4 (29%) patients during a small bowel enteroscopy. Mean age was 74.4 (±11). All patients were referred for work-up of gastrointestinal bleeding or anemia. 5 (35%) patients were treated for vascular lesions including AVMs or angioectasias, 4 (29%) patients for GAVE, 3 (21%) patients for radiation proctitis, and 2 (14%) patients for bleeding ulcers. Adequate hemostasis, defined by cessation of bleeding symptoms, lack of a 10g/L or more decrease in hemoglobin post-procedure, and no further endoscopic therapies in the subsequent 28 days, was achieved in 11 patients (79%). 2 of the 3 patients in which adequate hemostasis was not achieved had additional investigations in which a second source of bleeding was found and treated. 1 patient with colonic AVMs and 1 patient with radiation proctitis required a repeat treatment in 2 weeks and 6 months, respectively. There were no incidence of prolonged abdominal pain, perforations or deaths.

Conclusions

Snare tip spray coagulation appears to be a safe and effective modality for non-contact hemostasis. Larger studies will help solidify its use in daily practice.

Funding Agencies

None

An in situ shearing x-ray measurement system for exploring structures and dynamics at the solid-liquid interface

Revealing interfacial structure and dynamics has been one of the essential thematic topics in material science and condensed matter physics. Synchrotron-based x-ray scattering techniques can deliver unique and insightful probing of interfacial structures and dynamics, in particular, in reflection geometries with higher surface and interfacial sensitivity than transmission geometries. We demonstrate the design and implementation of an in situ shearing x-ray measurement system, equipped with both inline parallel-plate and cone-and-plate shearing setups and operated at the advanced photon source at Argonne National Laboratory, to investigate the structures and dynamics of end-tethered polymers at the solid-liquid interface. With a precise lifting motor, a micrometer-scale gap can be produced by aligning two surfaces of a rotating upper shaft and a lower sample substrate. A torsional shear flow forms in the gap and applies tangential shear forces on the sample surface. The technical combination with nanoscale rheology and the utilization of in situ x-ray scattering allow us to gain fundamental insights into the complex dynamics in soft interfaces under shearing. In this work, we demonstrate the technical scope and experimental capability of the in situ shearing x-ray system through the measurements of charged polymers at both flat and curved interfaces upon shearing. Through the in situ shearing x-ray scattering experiments integrated with theoretical simulations, we aim to develop a detailed understanding of the short-range molecular structure and mesoscale ionic aggregate morphology, as well as ion transport and dynamics in soft interfaces, thereby providing fundamental insight into a long-standing challenge in ionic polymer brushes with a significant technological impact.

Enrichment and Distribution of Pb2+ Ions in Zwitterionic Poly(cysteine methacrylate) Brushes at the Solid-Liquid Interface

Cysteine-based polyzwitterionic brushes have been prepared via a two-step route. First, poly(allyl methacrylate) (PAMA) brushes have been grown from the surface of silicon substrates using surface-initiated atom transfer radical polymerization. The obtained PAMA brushes with free pendant vinyl groups were further modified via radical thiol-ene addition reaction to attach l-cysteine moieties. Surface ζ potential investigations on pH-responsiveness of these poly(cysteine methacrylate) (PCysMA) brushes confirm their zwitterionic character at intermediate pH range, while at pH values either below pH 3.50 or above pH 8.59, they exhibit polyelectrolyte character. Under acid (pH < 3.50) or base (pH > 8.59) conditions, they possess either cationic or anionic character, respectively. In the zwitterionic region, these PCysMA brushes show positive surface ζ potential in the presence of Pb(CH₃COO)₂ solutions of various concentrations. The results are in line with microscopic investigations using anomalous X-ray reflectivity (AXRR) carried out along the absorption edge of Pb²⁺ ions. When the photon energies were varied around the absorption L3 edge of lead (13037 eV), the Pb²⁺ concentration normal to the silicon substrates, as a function of depth inside PCysMA brushes, could be revealed at the nanoscale. Both ζ potential and AXRR measurements confirm the enrichment of Pb²⁺ ions inside PCysMA brushes, indicating the potential of PCysMA to be used as a water purification material.

Stimulus-responsive vesicular polymer nano-integrators for drug and gene delivery

Over the past two decades, nano-sized biosystems have increasingly been utilized to deliver various pharmaceutical agents to a specific region, organ or tissue for controllable precision therapy. Whether solid nanohydrogel, nanosphere, nanoparticle, nanosheet, micelles and lipoproteins, or "hollow" nanobubble, liposome, nanocapsule, and nanovesicle, all of them can exhibit outstanding loading and releasing capability as a drug vehicle - in particular polymeric nanovesicle, a microscopic hollow sphere that encloses a water core with a thin polymer membrane. Besides excellent stability, toughness and liposome-like compatibility, polymeric nanovesicles offer considerable scope for tailoring properties by changing their chemical structure, block lengths, stimulus-responsiveness and even conjugation with biomolecules. In this review, we summarize the latest advances in stimulus-responsive polymeric nanovesicles for biomedical applications. Different functionalized polymers are in development to construct more complex multiple responsive nanovesicles in delivery systems, medical imaging, biosensors and so on.

Nano-sized Ultrasound Contrast Agents for Cancer Therapy and Theranostics

Ultrasound contrast agents (UCA) represented by gas-filled microbubble, can provide simultaneous and co-localized enhancement on image contrast to help disease diagnosis by highlighting tissue borders. Nowadays, Some UCAs (e.g. Levovist®, Optison®, Definity®, and Sonovue®) are commercially available, and have been clinically utilized for enhanced ultrasonography in the US, Canada, Europe, Asia and so on. However, their large diameters (1~10 µm) mainly hinder more precise and deeper applications in the imaging of capillaryabundant organs or tissues (e.g. tumor), and undersized nanoscale UCAs also lack enough backscattering echo intensity to distinguish abnormal distribution of vessels. So novel shapes, structures and materials of nano-sized UCAs are constantly emerging for cancer ultrasonic imaging. Particularly, the cavitation effect of diagnostic ultrasound can accelerate effusion of loaded contents from UCAs, following cellular uptake. This will inevitably contribute to develop other potential applications of nano-sized UCAs towards cancer therapy and theranostics.

Protonation-induced molecular permeation at the oil/water interface in an electric field

As a common physicochemical phenomenon, protonation can cause molecules, atoms or ions with lone-pair electrons to become charged, and can further cause some changes in their physical and chemical properties. Our study first focused on the molecular protonation process and accompanying transitions of the oil/water interface properties in an electric field. The relationship between the protonation degree increment and applied voltage was proposed as a guide for controlling the protonation via applying an electric field. Besides the protonation degree, the water solubility of the oily target molecule obviously increased at 30 V for 600 s along with electric field-driven protonation. At the same time, the electrical conductivity and the underwater interface wettability of oil phase transitioned. These property transitions are anticipated to guide the further improvement and updating of promising protonation functions.

Magnetic polymeric nanoassemblies for magnetic resonance imaging-combined cancer theranostics

Cancer has become one of the primary causes of death worldwide. Current cancer-therapy schemes are progressing relatively slowly in terms of reducing mortality, prolonging survival, time and enhancing cure rate, owing to the enormous obstacles of cancer pathophysiology. Therefore, specific diagnosis and therapy for malignant tumors are becoming more and more crucial and urgent, especially for early cancer diagnosis and cancer-targeted therapy. Derived theranostics that combine several functions into one "package" could further overcome undesirable differences in biodistribution and selectivity between distinct imaging and therapeutic agents. In this article, we discuss a chief clinical diagnosis tool - MRI - focusing on recent progress in magnetic agents or systems in multifunctional polymer nanoassemblies for combing cancer theranostics. We describe abundant polymeric MRI-contrast agents integrated with chemotherapy, gene therapy, thermotherapy, and radiotherapy, as well as other developing directions.

Application of vegetable oils in the treatment of polycyclic aromatic hydrocarbons-contaminated soils

A brief review is conducted on the application of vegetable oils in the treatment of PAH-contaminated soils. Three main scopes of treatment strategies are discussed in this work including soil washing by oil, integrated oil-biological treatment and integrated oil-non-biological treatment. For each of these, the arguments supporting vegetable oil application, the applied treatment techniques and their efficiencies, associated factors, as well as the feasibility of the techniques are detailed. Additionally, oil regeneration, the environmental impacts of oil residues in soil and comparison with other commonly employed techniques are also discussed.

Remediation of soils contaminated with polycyclic aromatic hydrocarbons (PAHs)

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic micropollutants which are resistant to environmental degradation due to their highly hydrophobic nature. Concerns over their adverse health effects have resulted in extensive studies on the remediation of soils contaminated with PAHs. This paper aims to provide a review of the remediation technologies specifically for PAH-contaminated soils. The technologies discussed here include solvent extraction, bioremediation, phytoremediation, chemical oxidation, photocatalytic degradation, electrokinetic remediation, thermal treatment and integrated remediation technologies. For each of these, the theories are discussed in conjunction with comparative evaluation of studies reported in the specialised literature.

Effects of cytokinin production under two SAG promoters on senescence and development of tomato plants

Two promoters of senescence-associated ARABIDOPSIS genes, SAG12 and SAG13, were used in tomato plants to express IPT that catalyzes the rate-limiting step in cytokinin biosynthesis. Expression of these heterologous promoters in tomato plants was analyzed using the reporter gene beta-glucuronidase. Both promoters are expressed in tomato leaves in a manner similar to their expression in ARABIDOPSIS plants. The SAG12 promoter is very specific to senescing leaves, whereas the SAG13 promoter is expressed in mature leaves prior to the onset of visible senescence and its expression increases in senescing leaves. Expression of both promoters in tomato tissues other than leaves was very low . IPT expressed under the control of SAG12 and SAG13 promoters ( PSAG12::IPT and PSAG13::IPT, respectively) resulted in suppression of leaf senescence and advanced flowering, as well as in a slight increase in fruit weight and fruit total soluble solids (TSS). However, expression of PSAG13::IPT also led to stem thickening, short internodal distances and loss of apical dominance. In contrast to the autoregulation of PSAG12::IPT, PSAG13::IPT is expressed at higher levels in mature leaves. This difference is likely due to PSAG13::IPT exhibiting two phases of expression - a senescence-independent expression prior to the onset of senescence that is not subjected to autoregulation by cytokinin, and enhanced expression throughout senescence which is autoregualted by cytokinin. This moderate different autoregulated behavior of PSAG12::IPT and PSAG13::IPT markedly influenced plant development, emphasizing the biological effects of cytokinin in addition to senescence inhibition.

MRI findings of eosinophilic myelomeningoencephalitis due to Angiostrongylus cantonensis

AIM

To study the imaging characteristics of eosinophilic myelomeningoencephalitis due to Angiostrongylus cantonensis using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Seventeen MRI examinations of the brain and spinal cord in five patients with angiostrongyliasis cantonensis of the central nervous system were performed. The final diagnosis was based on typical clinical symptoms, results of blood and cerebrospinal fluid (CSF) tests, and the presence of nematode larvae in the CSF. The sequential MRI follow-up examinations were carried out at a different stage for every patient from 1 to 28 weeks after the onset of symptoms. The features of the lesions in the brain, spinal cord, meninges and nerve roots on MRI were studied, moreover, the development of the lesions was analysed on follow-up MRI.

RESULTS

Abnormalities were demonstrated on MRI in all five cases. They included three cases of meningoencephalitis, one case of encephalitis and one myelomeningitis. The locations and appearances of the lesions were as follows: (1) brain involvement in four cases (including cerebrum in four, cerebellum in two and brain stem in three), and spinal cord involvement in one case. These lesions were diffuse or scattered and appeared as similar or slightly reduced signal intensity on T1-weighted images (T1WI), high signal intensity on T2-weighted images (T2WI) and turbo fluid attenuated inversion recovery pulse sequence (FLAIR) images. After administration of gadolinium chelate (Gd-DTPA), multiple round or oval enhancing nodules, with diameters ranging from 3 to 10 mm, were seen on T1WI, a few lesions appeared as stick-shaped enhancement whose longest measurement was 14 mm. Diffuse or local oedema around the lesion could be seen. (2) Meningeal involvement in four cases, a case of ependymal involvement and a case of nerve root involvement were among them. These lesions appeared as linear or nodular enhancement of the leptomeninges and ependyma, as well as nerve root enhancement. (3) There was a mild ventricular enlargement in two cases. On follow-up MRI lesions were most severe from the 5th week to the 8th week and it took at least 4-8 weeks (1-2 months) for a lesion to resolve completely, the resolution of larger lesion needed more than 22 weeks.

CONCLUSION

Multiple enhancing nodules in the brain and linear enhancement in the leptomeninges were the main features; stick-shaped enhancement was the characteristic sign of the disease on Gd-DTPA enhanced-T1 weighted images.

Identical promoter elements are involved in regulation of the OPR1 gene by senescence and jasmonic acid in Arabidopsis

Like other developmental processes, the terminal phase of leaf development, generally referred to as leaf senescence. regulates a subset of genes whose transcript abundances are increased during senescence. Jasmonic acid (JA), a plant growth regulator, also regulates the expression of subsets of genes in many aspects of plant growth and development, including leaf senescence. However, the underlying molecular mechanisms by which senescence and JA modulate gene expression are poorly understood. During an effort to isolate senescence-associated genes, we identified an Arabidopsis enhancer trap line in which the reporter gene GUS is up-regulated by both senescence and JA. The T-DNA tagged gene was subsequently cloned using thermal asymmetric interlaced PCR (TAIL-PCR). This gene encodes a 12-oxo-phytodienoic acid-10,11-reductase (OPR1). Consistent with the GUS expression data, RNA gel blot analysis showed that OPR1 was indeed up-regulated by both senescence and JA. Promoter deletion analysis and linker-scanning mutagenesis assays were employed to unveil the molecular bases of OPR1 regulation by senescence and JA. Two regulatory cis elements, namely JASE1 (5'-CGTCAATGAA-3') and JASE2 (5'-CATACGTCGTCAA-3'), in the promoter region of the gene, were identified. While JASE2 contains a mixed A/C box-like motif, JASE1 represents a new motif without any signature sequence so far reported. Both elements were required for the up-regulation of OPR1 by leaf senescence and JA. suggesting that leaf senescence and JA may share a common molecular mechanism for modulating OPR1.

Bidirectionalization of polar promoters in plants

A typical eukaryotic promoter consists of a minimal promoter and other upstream cis elements. The minimal promoter is essentially a TATA box region where RNA polymerase II, TATA-binding protein (TBP), and TBP-associated factors (TAFs) bind to initiate transcription, but minimal promoters alone have no transcriptional activity. The cis elements, to which tissue-specific or development-specific transcription factors bind, individually or in combination, determine the spatio-temporal expression pattern of a promoter at the transcriptional level. The arrangement of upstream cis elements followed by a minimal promoter sets the polarity of the promoter. Promoters in plants that have been cloned and widely used for both basic research and biotechnological application are generally unidirectional, directing only one gene that has been fused at its 3' end (downstream). It is often necessary to introduce multiple genes into plants for metabolic engineering and trait stacking. It is also desirable to minimize or avoid repeated use of a single promoter that may cause transcriptional gene silencing. Here we describe a strategy to make polar promoters bidirectional so that one promoter can direct the expression of two genes, one on each end of the promoter.

Networking senescence-regulating pathways by using Arabidopsis enhancer trap lines

The last phase of leaf development, generally referred to as leaf senescence, is an integral part of plant development that involves massive programmed cell death. Due to a sharp decline of photosynthetic capacity in a leaf, senescence limits crop yield and forest plant biomass production. However, the biochemical components and regulatory mechanisms underlying leaf senescence are poorly characterized. Although several approaches such as differential cDNA screening, differential display, and cDNA subtraction have been employed to isolate senescence-associated genes (SAGs), only a limited number of SAGs have been identified, and information regarding the regulation of these genes is fragmentary. Here we report on the utilization of enhancer trap approach toward the identification and analysis of SAGs. We have developed a sensitive large-scale screening method and have screened 1,300 Arabidopsis enhancer trap lines and have identified 147 lines in which the reporter gene GUS (beta-glucuronidase) is expressed in senescing leaves but not in non-senescing ones. We have systematically analyzed the regulation of beta-glucuronidase expression in 125 lines (genetically, each contains single T-DNA insertion) by six senescence-promoting factors, namely abscisic acid, ethylene, jasmonic acid, brassinosteroid, darkness, and dehydration. This analysis not only reveals the complexity of the regulatory circuitry but also allows us to postulate the existence of a network of senescence-promoting pathways. We have also cloned three SAGs from randomly selected enhancer trap lines, demonstrating that reporter expression pattern reflects the expression pattern of the endogenous gene.

Suppression of a P450 hydroxylase gene in plant trichome glands enhances natural-product-based aphid resistance

Trichome glands on the surface of many higher plants produce and secrete exudates affecting insects, microbes, and herbivores. Metabolic engineering of gland exudation has potential for improving pest/disease resistance, and for facilitating molecular farming. We identified a cytochrome P450 hydroxylase gene specific to the trichome gland and used both antisense and sense co-suppression strategies to investigate its function. P450-suppressed transgenic tobacco plants showed a > or =41% decrease in the predominant exudate component, cembratriene-diol (CBT-diol), and a > or =19-fold increase in its precursor, cembratriene-ol (CBT-ol). Thus, the level of CBT-ol was raised from 0.2 to > or =4.3% of leaf dry weight. Exudate from antisense-expressing plants had higher aphidicidal activity, and transgenic plants with exudate containing high concentrations of CBT-ol showed greatly diminished aphid colonization responses. Our results demonstrate the feasibility of significantly modifying the natural-product chemical composition and aphid-interactive properties of gland exudates using metabolic engineering. The results also have implications for molecular farming.

Markers for hypersensitive response and senescence show distinct patterns of expression

Controlled cellular suicide is an important process that can be observed in various organs during plant development. From the generation of proper sexual organs in monoecious plants to the hypersensitive response (HR) that occurs during incompatible pathogen interactions, programmed cell death (PCD) can be readily observed. Although several biochemical and morphological parameters have been described for various types of cell death in plants, the relationships existing between those different types of PCD events remain unclear. In this work, we set out to examine if two early molecular markers of HR cell death (HIN1 and HSR203J) as well as a senescence marker (SAG12) are coordinately induced during these processes. Our result indicates that although there is evidence of some cross-talk between both cell death pathways, spatial and temporal characteristics of activation for these markers during hypersensitive response and senescence are distinct. These observations indicate that these markers are relatively specific for different cell death programs. Interestingly, they also revealed that a senescence-like process seems to be triggered at the periphery of the HR necrotic lesion. This suggests that cells committed to die during the HR might release a signal able to induce senescence in the neighboring cells. This phenomenon could correspond to the establishment of a second barrier against pathogens. Lastly, we used those cell death markers to better characterize cell death induced by copper and we showed that this abiotic induced cell death presents similarities with HR cell death.

A comparison of the expression patterns of several senescence-associated genes in response to stress and hormone treatment

The expression of several Arabidopsis thaliana senescence-associated genes (SAGs) in attached and/or detached leaves was compared in response to age, dehydration, darkness, abscisic acid, cytokinin, and ethylene treatments. Most of the SAGs responded to most of the treatments in a similar fashion. Detachment in darkness and ethylene were the strongest inducers of both SAGs and visible yellowing. Detachment in light was also a strong inducer of SAGs, but not of visible yellowing. The other treatments varied more in their effects on individual SAGs. Responses were examined in both older and younger leaves, and generally were much stronger in the older ones. Individual SAGs differed from the norms in different ways, however, suggesting that their gene products play a role in overlapping but not identical circumstances. Some SAGs responded quickly to treatments, which may indicate a direct response. Others responded more slowly, which may indicate an indirect response via treatment-induced senescence. Four new SAGs were isolated as part of this work, one of which shows strong similarity to late embryogenesis-abundant (Lea) genes.

Inhibition of leaf senescence by autoregulated production of cytokinin

Controlling expression of IPT, a gene encoding isopentenyltransferase (the enzyme that catalyzes the rate-limiting step in cytokinin biosynthesis), with a senescence-specific promoter results in the suppression of leaf senescence. Transgenic tobacco plants expressing this chimeric gene do not exhibit the developmental abnormalities usually associated with IPT expression because the system is autoregulatory. Because sufficient cytokinin is produced to retard senescence, the activity of the senescence-specific promoter is attenulated. Senescence-retarded leaves exhibit a prolonged, photosythetically active life-span. This result demonstrates that endogenously produced cytokinin can regulate senescence and provides a system to specifically manipulate the senescence program.

Effect of various cytokine combinations on induction of non-MHC-restricted cytotoxicity

Efforts were directed to achieve an increased lymphokine-activated non-MHC-restricted killing (LAK) activity greater than that induced by rIL-2 alone. Human peripheral blood (PB) and bone marrow (BM)-derived mononuclear cells (MC) were exposed in vitro to multiple cytokine combinations, including rIL-6, rIL-7, rIFN-alpha and rIFN-gamma in the presence of either suboptimal or optimal doses of rIL-2. Our results have shown that BMMC are a potential source for induction of increased LAK activity upon exposure to multiple cytokine combinations, whereas PBMC could not be successfully stimulated under the same conditions. Fifty-five to 62% of BM-derived samples stimulated with high dose rIL-2 + rIL-7 or rIL-2 + rIL-7 + rIL-6 + rIFN-gamma exhibited a higher degree of cytotoxicity than BM samples stimulated with rIL-2 alone. Exposure of PB-derived large granular lymphocytes (LGL) to various cytokine combinations led to increased proliferation after stimulation with suboptimal dose of rIL-2 in the presence of rIL-6 and rIL-7. This increase was not observed in induction of cytotoxicity. We suggest that BMMC activated by multiple cytokine combinations could play an active role in improving antitumor response in vivo by contributing to the control of minimal residual tumor cell growth, particularly post-BM transplantation.

Normal hematopoietic reconstitution following ASTA-Z 7557-purged grafts in the absence of in vitro CFU-GM colony growth

Hematopoietic reconstitution was assessed in 26 consecutive patients who underwent autologous bone marrow transplantation (ABMT) with ASTA-Z 7557 purged bone marrows. Of the 26, 17 had acute non-lymphoblastic leukemia (ANLL), 7 had acute lymphoblastic leukemia (ALL), 1 had non-Hodgkin's lymphoma (NHL) and 1 had multiple myeloma (MM). Twelve patients had practically no CFU-GM growth after ASTA-Z treatment. No statistical difference was observed in hematopoietic reconstitution between patients with or without in vitro CFU-GM colony growth. No significant linear correlation was observed between CFU-GM content in the treated graft and day of engraftment. In vitro CFU-GM growth has no predictive value in assessing hematopoietic recovery in vivo. Patients with no CFU-GM growth demonstrated normal engraftment.

[Use of monoclonal antibodies for differentiating strains of the virus causing the hemorrhagic fever with renal syndrome]

Using monoclonal antibody and animal immune sera the experiment confirmed the existence of antigenic relationships between the strains of virus of hemorrhagic fever with renal syndrome (HFRS) isolated in the USSR from Clethrionomys glareolus and members of all known serotypes of HFRS virus. Clear-cut differentiation was made from serotypes Apodemus and Rattus, and cross-relationships were shown between the strains isolated in the USSR and Prospect Hill virus (PHV), a member of the serotype Microtus isolated in the USA.