Phenalenone-type phytoalexins mediate resistance of banana plants (Musa spp.) to the burrowing nematode Radopholus similis

The global yield of bananas—one of the most important food crops—is severely hampered by parasites, such as nematodes, which cause yield losses up to 75%. Plant–nematode interactions of two banana cultivars differing in susceptibility to Radopholus similis were investigated by combining the conventional and spatially resolved analytical techniques ¹H NMR spectroscopy, matrix-free UV-laser desorption/ionization mass spectrometric imaging, and Raman microspectroscopy. This innovative combination of analytical techniques was applied to isolate, identify, and locate the banana-specific type of phytoalexins, phenylphenalenones, in the R. similis-caused lesions of the plants. The striking antinematode activity of the phenylphenalenone anigorufone, its ingestion by the nematode, and its subsequent localization in lipid droplets within the nematode is reported. The importance of varying local concentrations of these specialized metabolites in infected plant tissues, their involvement in the plant’s defense system, and derived strategies for improving banana resistance are highlighted.Bananas and plantains (Musa spp.) are among the world’s most important food and cash crops, with a global production of about 138 million tons in 2010. These crops are part of a well-balanced human diet and are a major food staple for more than 400 million people in the tropics (1, 2). About 82% of the world’s banana production is consumed locally, particularly in India, China, and many African countries (Table S1) (1, 2). Export of bananas to the northern hemisphere represents an important source of employment in countries such as Costa Rica, Ecuador, Colombia, and the Philippines (Table S2) (1, 2). Banana yields are severely hampered by fungi, insects, and plant-parasitic nematodes. The burrowing nematode, Radopholus similis (Cobb, 1893) Thorne, 1949, is the key nematode pathogen, causing yield losses up to 75% (3). R. similis is found in all major banana-producing regions of the world; its best-known hosts are bananas, black pepper, Citrus spp. (4), and coffee (5). R. similis causes extensive root lesions that can lead to toppling of banana plants (6).Plant-parasitic nematodes have been effectively managed through the use of nematicides. However, their high toxicity has adverse effects on humans and their toxic residues are known to accumulate through nontarget organisms in the food chain (7). After the withdrawal of many effective nematicides, such as methyl bromide, from the market (8), organophosphate and carbamate nematicides are still intensively applied to banana and therefore continue to threaten the health of agricultural workers and the environment (9). Although several biological control approaches, including the application of both single and multiple control organisms—such as Fusarium oxysporum, Paecilomyces lilacinus, Trichoderma atroviride isolates, and Bacillus firmus—have proved promising under greenhouse conditions, the control they confer to banana plants most probably does not protect plants for more than one cycle in the field, and most of these organisms have yet to be tested under field conditions (10).The in-depth investigation of the plant–nematode interactions at the cellular and molecular level could lead to the development of more rational and efficient control strategies (11). The production of toxic, herbivore-deterrent or -repellent secondary metabolites, which is typical for many plant defense systems, is particularly interesting in this context. Musa cultivars resistant to R. similis have been identified, especially the cultivar Yangambi km5 (Ykm5) (12). Histochemical and ultrastructural investigations of lesions caused by R. similis in Ykm5 revealed the accumulation of phenolic compounds in response to infection (13). Unfortunately, many of these studies were based solely on histochemical staining methods and did not identify the chemical structures of nematicidal secondary metabolites (7, 14, 15). Initial phytochemical analyses of R. similis-infected roots of the Musa cultivar Pisang sipulu identified the phenylphenalenone anigorufone (1) as a phytoalexin produced in response to nematode damage and confirmed earlier suggestions of the significant role of phytoalexins in the plant defense system (16). Phenylphenalenones are a group of special phenylpropanoid-derived natural products (17), which are known as Musaceae phytoalexins (18). The activity of phenylalanine ammonia lyase (EC 4.3.15), the entry-point enzyme of the phenylpropanoid pathway, is correlated to the biosynthesis of specific phenylpropanoids involved in defense and was substantially induced in nematode infected roots of Ykm5 (19). Phenylphenalenone-related compounds show biological activity against bacteria, fungi, algae, and diatoms (18, 20–22). The formation of these compounds has been elicited in banana leaves by Mycosphaerella fijiensis (Black Sigatoka leaf streak disease), in the fruit peels by Colletotrichum musae (anthracnose disease), and in roots and rhizomes by F. oxysporum f. sp. cubense (Panama disease) and R. similis (16, 18, 21, 23).     

Laparoscopic transperitoneal dismembered pyeloplasty for ureteropelvic junction obstruction

PURPOSE: To review the outcome of transperitoneal laparoscopic dismembered pyeloplasty (LDP) in our institution. PATIENTS AND METHODS: From April 2001 to April 2005, 36 men and 34 women underwent LDP for symptomatic and radiologically proved ureteropelvic junction (UPJ) obstruction. A successful outcome was defined clinically by improvement in symptoms and objectively by improvement in the diuretic renography study performed at 3 and 12 months after reconstruction. RESULTS: The mean operative time was 160.5 +/- 45 minutes with a mean blood loss of 77.8 +/- 52.8 mL. There were no conversions to open surgery. Lower-pole vessels were observed in 38 patients (54.3%). In all cases, the ureter was transposed anteriorly. The mean hospital stay was 3.3 +/- 2.1 days. Postoperative complications were recorded in 4 patients (5.7%). One patient developed an anastomotic stricture. A successful outcome was achieved in 68 of the 70 patients (97.1%) at a mean follow-up of 27.6 +/- 13.2 months. CONCLUSION: Our results further strengthen the evidence that LDP has a reliable medium-term outcome with the added benefit of being minimally invasive.     

Hepatic hemangioendothelioma: CT,MR, and FDG-PET-CT in 67 patients—a bi-institutional comprehensive cancer center review

European Radiology - To evaluate the imaging features of hepatic epithelioid hemangioendothelioma (HEH) on multiphasic CT, MR, and FDG-PET-CT. Bi-institutional review identified 67 adults (mean...     

Current update on imaging for pancreatic neuroendocrine neoplasms

Pancreatic neuroendocrine neoplasms (panNEN) are a heterogeneous group of tumors with differing pathological, genetic, and clinical features. Based on clinical findings, they may be categorized into functioning and nonfunctioning tumors. Adoption of the 2017 World Health Organization classification system, particularly its differentiation between grade 3, well-differentiated pancreatic neuroendocrine tumors (panNET) and grade 3, poorly-differentiated pancreatic neuroendocrine carcinomas (panNEC) has emphasized the role imaging plays in characterizing these lesions. Endoscopic ultrasound can help obtain biopsy specimen and assess tumor margins and local spread. Enhancement patterns on computed tomography (CT) and magnetic resonance imaging (MRI) may be used to classify panNEN. Contrast enhanced MRI and diffusion-weighted imaging have been reported to be useful for characterization of panNEN and quantifying metastatic burden. Current and emerging radiotracers have broadened the utility of functional imaging in evaluating panNEN. Fluorine-18 fluorodeoxyglucose positron emission tomography (PET)/CT and somatostatin receptor imaging such as Gallium-68 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid–octreotate PET/CT may be useful for improved identification of panNEN in comparison to anatomic modalities. These new techniques can also play a direct role in optimizing the selection of treatment for individuals and predicting tumor response based on somatostatin receptor expression. In addition, emerging methods of radiomics such as texture analysis may be a potential tool for staging and outcome prediction in panNEN, however further investigation is required before clinical implementation.     

Iron Oxide Nanoparticles Induces Cell Cycle-Dependent Neuronal Apoptosis in Mice

Iron oxide (Fe₂O₃) nanoparticles (NPs) with its unique magnetic and paramagnetic properties are popular in biomedical applications. Some of their neurotoxic mechanisms due to repeated administration are proven. However, we speculate that the neuronal damage might be due to apoptosis resulting from unusual cell cycle entry. Moreover, iron accumulation has been shown to be closely associated with most of the neurodegenerative disorders. Thus, in the current study, mice were orally (po) treated with the Fe₂O₃-NPs to investigate cell cycle-associated events/components and occurrence of apoptosis. A subsequent increase in oxidant levels was observed with the iron accumulation due to Fe₂O₃-NPs exposure. The accumulated β-amyloid and reduced level of cdk5 seem to aid in the cell cycle entry and forcing progression towards apoptosis. Expression of Cyclin D1 and pRb (Ser 795) indicate the cell cycle re-entry of neurons. Overexpression of RNA Pol II and PARP cleavage suggests DNA damage due to Fe₂O₃-NPs exposure. Further, hyperphosphorylation of p38 (Thr 180/Tyr 182) confirms the activation of DNA damage-dependent checkpoint. Expression patterns of pro- and anti-apoptotic markers, TUNEL and TEM indicate the occurrences of apoptosis.     

Beyond adenocarcinoma: MRI of uncommon rectal neoplasms and mimickers

Abdominal Radiology - To provide a review of rare rectal tumors beyond adenocarcinoma. Rectal cancer is a common malignancy, both in the United States and abroad. In addition to adenocarcinoma,...     

Features of primary pancreatic lymphoma: A bi-institutional review with an emphasis on typical and atypical imaging features

BACKGROUNDPrimary pancreatic lymphoma (PPL) is a rare neoplasm. Being able to distinguish it from other pancreatic malignancies such as pancreatic ductal adenocarcinoma (PDAC) is important for appropriate management. Unlike PDAC, PPL is highly sensitive to chemotherapy and usually does not require surgery. Therefore, being able to identify PPL preoperatively will not only direct physicians towards the correct avenue of treatment, it will also avoid unnecessary surgical intervention.AIMTo evaluate the typical and atypical multi-phasic computed tomography (CT) imaging features of PPL.METHODSA retrospective review was conducted of the clinical, radiological, and pathological records of all subjects with pathologically proven PPL who presented to our institutions between January 2000 and December 2020. Institutional review board approval was obtained for this investigation. The collected data were analyzed for subject demographics, clinical presentation, laboratory values, CT imaging features, and the treatment received. Presence of all CT imaging findings including size, site, morphology and imaging characteristics of PPL such as the presence or absence of nodal, vascular and ductal involvement in these subjects were recorded. Only those subjects who had a pre-treatment multiphasic CT of the abdomen were included in the study.RESULTSTwenty-nine cases of PPL were diagnosed between January 2000 and December 2020 (mean age 66 years; 13 males/16 females). All twenty-nine subjects were symptomatic but only 4 of the 29 subjects (14%) had B symptoms. Obstructive jaundice occurred in 24% of subjects. Elevated lactate dehydrogenase was seen in 81% of cases, whereas elevated cancer antigen 19-9 levels were present in only 10% of cases for which levels were recorded. The vast majority (90%) of tumors involved the pancreatic head and uncinate process. Mean tumor size was 7.8 cm (range, 4.0-13.8 cm). PPL presented homogenous hypoenhancement on CT in 72% of cases. Small volume peripancreatic lymphadenopathy was seen in 28% of subjects. Tumors demonstrated encasement of superior mesenteric vessels in 69% of cases but vascular stenosis or occlusion only manifested in 5 out of the twenty-nine individuals (17%). Mild pancreatic duct dilatation was also infrequent and seen in only 17% of cases, whereas common bile duct (CBD) dilation was seen in 41% of subjects. Necrosis occurred in 10% of cases. Size did not impact the prevalence of pancreatic and CBD dilation, necrosis, or mesenteric root infiltration (P = 0.525, P = 0.294, P = 0.543, and P = 0.097, respectively). Pancreatic atrophy was not present in any of the subjects.CONCLUSIONPPL is an uncommon diagnosis best made preoperatively to avoid unnecessary surgery and ensure adequate treatment. In addition to the typical CT findings of PPL, such as homogeneous hypoenhancement, absence of vascular stenosis and occlusion despite encasement, and peripancreatic lymphadenopathy, this study highlighted many less typical findings, including small volume necrosis and pancreatic and bile duct dilation.     

Neurobehavioural Toxicity of Iron Oxide Nanoparticles in Mice

Postnatal development of the cerebellar cortex was studied in rats administered with a single dose (2 mg/g) of the cytotoxic agent hydroxyurea (HU) on postnatal day (P) 9 and collected at appropriate times ranging from 6 h to 45 days. Quantification of several parameters such as the density of pyknotic, mitotic, BrdU-positive, and vimentin-stained cells revealed that HU compromises the survival of the external granular layer (EGL) cells. Moreover, vimentin immunocytochemistry revealed overexpression and thicker immunoreactive glial processes in HU-treated rats. On the other hand, we also show that HU leads to the activation of apoptotic cellular events, resulting in a substantial number of dying EGL cells, as revealed by TUNEL staining and at the electron microscope level. Additionally, we quantified several features of the cerebellar cortex of rats exposed to HU in early postnatal life and collected in adulthood. Data analysis indicated that the analyzed parameters were less pronounced in rats administered with this agent. Moreover, we observed several alterations in the cerebellar cortex cytoarchitecture of rats injected with HU. Anomalies included ectopic placement of Purkinje cells and abnormities in the dendritic arbor of these macroneurons. Ectopic granule cells were also found in the molecular layer. These findings provide a clue for investigating the mechanisms of HU-induced toxicity during the development of the central nervous system. Our results also suggest that it is essential to avoid underestimating the adverse effects of this hydroxylated analog of urea when administered during early postnatal life.