Abdominal wall and labial edema presenting in a girl with Henoch-Schönlein purpura: a case report

Introduction

We report a rare case of gastrointestinal perforation following dacarbazine infusion for metastatic melanoma. The condition is attributed to a responding malignant melanoma in the gastrointestinal tract.

Case presentation

A 52-year-old Caucasian man presented with abdominal pain and distension, malaise, night sweats, dysphagia and early satiety. A computed tomography scan showed massive ascites, lymphadenopathy and liver lesions suspect for metastases. An upper gastrointestinal endoscopy was performed and revealed multiple dark lesions of 5 mm to 10 mm in his stomach and duodenum. When his skin was re-examined, an irregular pigmented lesion over the left clavicle measuring 15 mm × 8 mm with partial depigmentation was found. Histological examination of a duodenal lesion was consistent with a diagnosis of metastatic melanoma. The patient deteriorated and his level of lactate dehydrogenase rapidly increased. The patient was started on systemic treatment with dacarbazine 800 mg/m² every three weeks and he was discharged one day after the first dose. On the sixth day he was readmitted with severe abdominal pain. A chest X-ray showed the presence of free intraperitoneal air that was consistent with gastrointestinal perforation. His lactate dehydrogenase level had fallen from 6969U/L to 1827U/L, supporting the conclusion that the response of gastrointestinal metastases to dacarbazine had resulted in the perforation of the patient's bowel wall. A laparotomy was discussed with the patient and his family but he decided to go home with symptomatic treatment. He died 11 days later.

Conclusion

Melanoma can originate in, as well as metastasize to, the gastrointestinal tract. Gastrointestinal perforations due to responding tumors are a well-known complication of systemic treatment of gastrointestinal lymphomas. However, as the response rate of metastatic melanoma to dacarbazine is only 10% to 20%, and responses are usually only partial, perforation due to treatment response in metastatic melanoma is rare. Medical oncologists should be aware of the risk of bowel perforation after starting cytotoxic chemotherapy on patients with gastrointestinal metastases.     

Deciphering protein function during mitosis in PtK cells using RNAi

Background  

Studying mitosis requires a system in which the dramatic movements of chromosomes and spindle microtubules can be visualized. PtK cells, due to their flat morphology and their small number of large chromosomes, allow microscopic visualizations to be readily performed.     

K-ras4B and prenylated proteins lacking "second signals" associate dynamically with cellular membranes

We have used fluorescence microscopy and the technique of rapamycin-regulated protein heterodimerization to examine the dynamics of the subcellular localizations of fluorescent proteins fused to lipid-modified protein sequences and to wild-type and mutated forms of full-length K-ras4B. Singly prenylated or myristoylated fluorescent protein derivatives lacking a "second signal" to direct them to specific subcellular destinations, but incorporating a rapamycin-dependent heterodimerization module, rapidly translocate to mitochondria upon rapamycin addition to bind to a mitochondrial outer membrane protein incorporating a complementary heterodimerization module. Under the same conditions analogous constructs anchored to the plasma membrane by multiply lipid-modified sequences, or by a transmembrane helix, show very slow or no transfer to mitochondria, respectively. Interestingly, however, fluorescent protein constructs incorporating either full-length K-ras4B or its plasma membrane-targeting sequence alone undergo rapamycin-induced transfer from the plasma membrane to mitochondria on a time scale of minutes, demonstrating the rapidly reversible nature of K-ras4B binding to the plasma membrane. The dynamic nature of the plasma membrane targeting of K-ras4B could contribute to K-ras4B function by facilitating redistribution of the protein between subcellular compartments under particular conditions.     

Reproduction of the salamander Siren intermedia le conte with especial reference to oviducal anatomy and mode of fertilization

Reproduction was studied in a South Carolina population of the paedomorphic salamander Siren intermedia with emphasis on anatomy of the female oviduct. The oviduct forms 67–79% of the snout-vent length in this elongate species and can be divided into three portions. The atrium, 7–13% of oviducal length, is the narrow anteriormost portion, with the ostial opening immediately caudad of the transverse septum. The ampulla, 63–75% of oviducal length, is the highly convoluted, middle portion in which gelatinous coverings are added to the eggs during their passage. Hypertrophy of the oviducal glands in the ampulla causes the ampulla to increase in diameter during the ovipository season. The secretion of the eosinophilic oviducal glands is intensely positive following staining with the periodic acid-Schiff procedure and does not react with alcian blue at pH 2.5. This staining reaction, coupled with the presence of abundant rough endoplasmic reticulum and Golgi complexes, indicates that the secretion contains a glycoprotein. The ovisac, 16–25% of oviducal length, is the most posterior portion of the oviduct and holds up to 10–11 eggs prior to oviposition. Oviducal glands similar to those in the ampulla are absent in the ovisac. Oviposition in female sirens occurs during February-April in this population, and male spermiation is concurrent. Entire oviducts were sectioned from three females collected during the ovipository season and from two collected prior to the breeding season, and sperm were not found in the oviducts of these specimens. Thus no evidence was found for internal fertilization or sperm storage in the oviducts of sirens. © 1996 Wiley-Liss, Inc.     

Association of ABCA1 with syntaxin 13 and flotillin-1 and enhanced phagocytosis in tangier cells

The ATP-binding cassette transporter A1 (ABCA1) facilitates the cellular release of cholesterol and choline-phospholipids to apolipoprotein A-I (apoA-I) and several studies indicate that vesicular transport is associated with ABCA1 function. Syntaxins play a major role in vesicular fusion and have also been demonstrated to interact with members of the ABC-transporter family. Therefore, we focused on the identification of syntaxins that directly interact with ABCA1. The expression of syntaxins and ABCA1 in cultured human monocytes during M-CSF differentiation and cholesterol loading was investigated and syntaxins 3, 6, and 13 were found induced in foam cells together with ABCA1. Immunoprecipitation experiments revealed a direct association of syntaxin 13 and full-length ABCA1, whereas syntaxin 3 and 6 failed to interact with ABCA1. The colocalization of ABCA1 and syntaxin 13 was also shown by immunofluorescence microscopy. Silencing of syntaxin 13 by small interfering RNA (siRNA) led to reduced ABCA1 protein levels and hence to a significant decrease in apoA-I-dependent choline-phospholipid efflux. ABCA1 is localized in Lubrol WX-insoluble raft microdomains in macrophages and syntaxin 13 and flotillin-1 were also detected in these detergent resistant microdomains along with ABCA1. Syntaxin 13, flotillin-1, and ABCA1 were identified as phagosomal proteins, indicating the involvement of the phagosomal compartment in ABCA1-mediated lipid efflux. In addition, the uptake of latex phagobeads by fibroblasts with mutated ABCA1 was enhanced when compared with control cells and the recombinant expression of functional ABCA1 normalized the phagocytosis rate in Tangier fibroblasts. It is concluded that ABCA1 forms a complex with syntaxin 13 and flotillin-1, residing at the plasma membrane and in phagosomes that are partially located in raft microdomains.     

Artificially lipid-anchored proteins can elicit clustering-induced intracellular signaling events in Jurkat T-lymphocytes independent of lipid raft association

We have incorporated artificial lipid-anchored streptavidin conjugates with fully saturated or polyunsaturated lipid anchors into the plasma membranes of Jurkat T-lymphocytes to assess previous conclusions that the activation of signaling processes induced in these cells by clustering of endogenous glycosylphosphatidylinositol-anchored proteins or ganglioside GM1 depends specifically on the association of these membrane components with lipid rafts. Lipid-anchored streptavidin conjugates could be incorporated into Jurkat or other mammalian cell surfaces by inserting biotinylated phosphatidylethanolamine-polyethyleneglycols (PE-PEGs) and subsequently binding streptavidin to the cell-incorporated PE-PEGs. Saturated dipalmitoyl-PE-PEG-streptavidin conjugates prepared in this manner partitioned substantially into the detergent-insoluble membrane fraction isolated from Jurkat or fibroblast cells, whereas polyunsaturated dilinoleoyl-PE-PEG-anchored conjugates were wholly excluded from this fraction, consistent with the differences in the affinities of the two types of lipid anchors for liquid-ordered membrane domains. Remarkably, however, antibody-mediated cross-linking of either dipalmitoyl- or dilinoleoyl-PE-PEG-anchored streptavidin conjugates in Jurkat cells induced elevation of cytoplasmic calcium levels and tyrosine phosphorylation of the scaf-folding protein linker of T-cell activation in a manner similar to that observed upon cross-linking of endogenous CD59 or ganglioside GM1. The amplitude of the cross-linking-stimulated elevation of cytoplasmic calcium moreover showed an essentially identical dependence on the level of incorporated streptavidin conjugate for either type of lipid anchor. Confocal fluorescence microscopy revealed that PE-PEG-streptavidin conjugates with saturated versus polyunsaturated anchors showed very similar surface distributions vis à vis GM1 or CD59 under conditions where one or both species were cross-linked. These results indicate that cross-linking of diverse proteins anchored only to the outer leaflet of the plasma membrane can induce activation of Jurkat T-cell-signaling responses, but they appear to contradict previous suggestions that this phenomenon rests specifically on the association of such species with lipid rafts.     

Phosphorylated osteopontin promotes migration of human choriocarcinoma cells via a p70 S6 kinase-dependent pathway

This study examined the role of osteopontin (OPN), a phosphorylated secreted glycoprotein, in the promotion of trophoblastic cell migration, an early event in the embryo implantation process. Three human choriocarcinoma cell lines, namely JAR, BeWo, and JEG-3, were treated with variants of OPN differing in the extent of phosphorylation following sequential dephosphorylation with tartrate-resistant acid phosphatase (TRAP), and their migratory response was measured. The highly phosphorylated human milk form of OPN (OPN-1) strongly triggered migration in all three cell lines, whereas the less phosphorylated variants, OPN-2a and OPN-2b, failed to stimulate migration. JAR cell migration in response to OPN-1 was accompanied by a rapid rearrangement of actin filaments to the cellular membrane. Using broad spectrum protein kinase profiling, we identified p70 S6 kinase as a major signal transduction pathway activated by OPN-1 during the migratory response in JAR cells. Activation was blocked completely by rapamycin and LY294002, thus demonstrating that OPN-1-stimulated migration occurs through mTOR and PI3K pathways, respectively. Conversely, PD98059 did not affect the activation of p70 S6 kinase by OPN-1, therefore, this response does not involve the Ras/ MAPK signaling cascade. Together, these data show that the highly phosphorylated human OPN-1 can stimulate trophoblastic cell migration and provides evidence for the involvement of the PI3K/mTOR/p70 S6 kinase pathway in the JAR cells response. Because both OPN and TRAP are expressed in the uterus during early pregnancy, it is conceivable that extracellular phosphatases such as TRAP may modify OPN charge state and thus modulate cell migration.     

Synthesis of novel pyrroles and fused pyrroles as antifungal and antibacterial agents

Pyrroles and its fused forms possess antimicrobial activities, they can easily interact with biomolecules of living systems. A series of substituted pyrroles, and its fused pyrimidines and triazines forms have been synthesised, all newly synthesised compound structures were confirmed by spectroscopic analysis. Generally, the compounds inhibited growth of some important human pathogens, the best effect was given by: 2a, 3c, 4d on Gram-positive bacteria and was higher on yeast (C. albicans), by 5c on Gram-negative bacteria and by 5a then 3c on filamentous fungi (A. fumigatus and F. oxysporum). Such results present good antibacterial and antifungal potential candidates to help overcome the global problem of antibiotic resistance and opportunistic infections outbreak. Compound 3c gave the best anti-phytopathogenic effect at a 50-fold lower concentration than Kocide 2000, introducing a safe commercial candidate for agricultural use. The effect of the compounds on DNA was monitored to detect the mode of action.