The induction of acute ileitis by a single microbial antigen of Toxoplasma gondii

The role of specific microbial Ags in the induction of experimental inflammatory bowel disease is poorly understood. Oral infection of susceptible C57BL/6 mice with Toxoplasma gondii results in a lethal ileitis within 7-9 days postinfection. An immunodominant Ag of T. gondii (surface Ag 1 (SAG1)) that induces a robust B and T cell-specific response has been identified and a SAG1-deficient parasite (Deltasag1) engineered. We investigated the ability of Deltasag1 parasite to induce a lethal intestinal inflammatory response in susceptible mice. C57BL/6 mice orally infected with Deltasag1 parasites failed to develop ileitis. In vitro, the mutant parasites replicate in both enterocytes and dendritic cells. In vivo, infection with the mutant parasites was associated with a decrease in the chemokine and cytokine production within several compartments of the gut-associated cell population. RAG-deficient (RAG1(-/-)) mice are resistant to the development of the ileitis after T. gondii infection. Adoptive transfer of Ag-specific CD4(+) effector T lymphocytes isolated from C57BL/6-infected mice into RAG(-/-) mice conferred susceptibility to the development of the intestinal disease. In contrast, CD4(+) effector T lymphocytes from mice infected with the mutant Deltasag1 strain failed to transfer the pathology. In addition, resistant mice (BALB/c) that fail to develop ileitis following oral infection with T. gondii were rendered susceptible following intranasal presensitization with the SAG1 protein. This process was associated with a shift toward a Th1 response. These findings demonstrate that a single Ag (SAG1) of T. gondii can elicit a lethal inflammatory process in this experimental model of pathogen-driven ileitis.     

Trace elemental analysis of cancer-afflicted intestine by PIXE technique

Trace elemental analysis was carried out in the biological samples of cancer-afflicted intestine using the particle-induced X-ray emission technique (PIXE). A 2-MeV proton beam was employed to excite the samples. From the present results, it can be seen that the concentration of the elements Cr, Fe, and Ni are higher in the cancerous tissue of the intestine than those observed in the normal tissue, whereas the concentration levels of the element Zn is slightly lower in the cancer tissue of intestine than that observed in the normal tissue. The concentrations of S, Cl, K, Ca, Ti, Mn, Co, and Cu in the cancer tissue of the intestine are in agreement with those observed in the normal tissues within standard deviations. The present results support the previous observations that Ni and Cr are carcinogenic agents. The observed slightly low levels of zinc in the cancer tissue of the intestine suggest that zinc could possibly inhibit the tumor growth and development of neoplastic transformation. For correctly assessing the role played by the trace elements in initiating, promoting, or inhibiting cancer in various organs, there is a need for the acquisition of more data by trace elemental analysis from several investigations of this type undertaken in different regions.     

Large macromolecular complexes in the Protein Data Bank: a status report

The growing number of large macromolecular complexes in the Protein Data Bank (PDB) has warranted a closer look at these structures. An overview of the types of molecules that form these large complexes is presented here. Some of the challenges at the PDB in representing, archiving, visualizing, and analyzing these structures are discussed along with possible means to overcome them.     

Terahertz vibrational signature of bacterial spores arising from nanostructure decorated endospore surface

This theoretical effort is the first to explore the possible hypothesis that terahertz optical activity of Bacillus spores arises from normal vibrational modes of spore coat subcomponents in the terahertz frequency range. Bacterial strains like Bacillus and Clostridium form spores with a hardened coating made of peptidoglycan to protect its genetic material in harsh conditions. In recent years, electron microscopy and atomic force microscopy has revealed that bacterial spore surfaces are decorated with nanocylinders and honeycomb nanostructures. In this article, a simple elastic continuum model is used to describe the vibration of these nanocylinders mainly in Bacillus subtilis, which also leads to the conclusion that the terahertz signature of these spores arises from the vibration of these nanostructures. Three vibrating modes: radial/longitudinal, torsional and flexural, have been identified and discussed for the nanocylinders. The effect of bound water, which shifts the vibration frequency, is also discussed. The peptidoglycan molecule consists of polar and charged amino acids; hence, the sporal surface local vibrations interact strongly with the terahertz radiation.      

Characterization of lipopolysaccharide heterogeneity in Salmonella enteritidis by an improved gel electrophoresis method.

Salmonella enteritidis field isolates of different phage types and pathogenicities were assessed for changes in lipopolysaccharide (LPS) structure, using an improved method of polyacrylamide gel electrophoresis (PAGE) that revealed the same degree of structural detail as mass spectroscopy. The method allowed characterization of an LPS chemotype that may be associated, regardless of phage type, with increased virulence of S. enteritidis. The virulent variant SE6-E21, which efficiently contaminates eggs and yields high numbers of organisms from chick spleens, had an O-antigen/core ratio of 2.8, as determined from gels by densitometry, and 1.67 micrograms of mannose per microgram of 2-keto-3-deoxy-octulosonic acid (KDO), while the avirulent variant SE6-E5 had O-antigen/core ratios of 1.2 and 1.00. The association between O antigen and virulence was also seen on analysis of five new field isolates. One of the new field isolates generated a mixed population of smooth and semismooth variants in agreement with its mixed virulence in chicks. When LPS was purified from large-volume cultures, only the most virulent isolate yielded high amounts of O antigen (1.6 micrograms of mannose per microgram of KDO), while the other isolates had ratios characteristic of semismooth variants (< or = 1.0 microgram of mannose per microgram of KDO), including the isolate of mixed virulence. These results indicate that the improved PAGE method might provide a rapid, sensitive, in vitro assessment of field isolate virulence prior to the performance of definitive infectivity trials.     

Direct somatic embryogenesis and plantlet regeneration from cotyledonary leaves of safflower

Somatic embryos were induced directly on adaxial surface of cotyledonary leaves within 8–10 days of culture on Murashige and Skoog medium containing 5.37 to 10.74 M 1 — napthaleneacetic acid and 2.22 M benzyl adenine. Germinated embryos with shoot axes developed into complete plants after transfer onto half stength Murashige and Skoog medium containing 1.07 M 1 — napthaleneacetic acid. Histological studies suggested direct origin of somatic embryos with broad-base attachment.Abbreviations BA benzyl adenine - MS Murashige and Skoog - NAA 1-napthaleneacetic acid - RH relative humidity     

Monoterpenoid furanocoumarin lactones from clausena anisata

A reinvestigation of Clausena anisata has yielded imperatorin, xanthotoxol, lansamide-I and three new furanocoumarin lactone derivatives: indicolactone, anisolactone and 2′,3′-epoxyanisolactone. The structures of these compounds have been elucidated by a combination of spectroscopic and chemical methods.     

Potent cyclic peptide inhibitors of VLA-4 (alpha4beta1 integrin)-mediated cell adhesion. Discovery of compounds like cyclo(MePhe-Leu-Asp-Val-D-Arg-D-Arg) (ZD7349) compatible with depot formulation.

Additional structure-activity relationship studies on potent cyclic peptide inhibitors of very late antigen-4 (VLA-4) are reported. The new N- to C-terminal cyclic hexa-, hepta- and octapeptide inhibitors like cyclo(MeIle/MePhe-Leu-Asp-Val-X) (X = 2-4 amino acids containing hydrophobic and/or basic side chains) were synthesized using solid phase peptide synthesis methods. The peptides were evaluated in in vitro cell adhesion assays and in in vivo inflammation models. Many of the peptides like cyclo(MePhe-Leu-Asp-Val-D-Arg-D-Arg) (ZD7349) (17), cyclo(MeIle-Leu-Asp-Val-D-Arg-D-Arg-D-Phe) (20), cyclo(MeIle-Leu-Asp-Val-D-Arg-D-Arg-MePhe) (21) and cyclo(MePhe-Leu-Asp-Val-D-Arg-D-Arg-D-Ala-D-Ala) (23) were potent inhibitors of VLA-4-mediated cell adhesion and inhibited ovalbumin-induced delayed type hypersensitivity (DTH) response in mice. The more potent compounds were highly selective and did not affect U937 cell adhesion to fibronectin (VLA-5), phorbolmyristate acetate or PMA-differentiated U937 cell adhesion to intercellular cell adhesion molecule-1 (ICAM-1)-expressing Chinese hamster ovary cells (LFA-1) and adenosine diphosphate (ADP)-induced platelet aggregation (GPIIb/IIIa). In contrast to the inhibitors like Ac-cyclo(D-Lys-D-Ile-Leu-Asp-Val) and cyclo(CH2CO-Ile-Leu-Asp-Val-Pip-CH2CO-Ile-Leu-Asp-Val-Pip) described earlier, the new compounds were much more compatible with the depot formulations based on poly(DL-lactide-co-glycolide) polymers. The hexapeptide cyclo(MePhe-Leu-Asp-Val-D-Arg-D-Arg) (ZD7349) (17) inhibited MOLT-4 cell adhesion to fibronectin and vascular cell adhesion molecule-1 (VCAM-1) with IC50 values of 260 and 330 nM, respectively, and did not show any significant effect against other integrins (IC50 > 300 microM). ZD7349 inhibited ovalbumin-induced DTH response in mice when administered continuously using a mini-pump (ED50 0.01 mg/kg/day) or when given as an s.c. or i.v. bolus injection at a dose of 1-10 mg/kg. ZD7349 was also active in type II collagen-induced arthritis (CIA) and experimental autoimmune encephalomyelitis (EAE) tests at a dose of 3-10 mg/kg. The peptide was released from some formulations over a period of 10-20 days. ZD7349 is currently undergoing pre-clinical investigation.     

Relevance of plant lectins in human cell biology and immunology.

Protein-carbohydrate interactions are used for intercellular communication. Mammalian cells are known to bear a variety of glycoconjugates. Lectins, first discovered in plants, are proteins which can specifically bind carbohydrates. Given the high affinity of plant lectins for carbohydrates, they have always been important as molecular tools in the identification, purification and stimulation of specific glycoproteins on human cells. Lectins have provided important clues to the repertoire of carbohydrate structures in animal cells. The discovery of plant lectins gave a great impulse to modern glycobiology. They represent important biochemical reagents for numerous applications in the biomedical field and in research. Sequence determinations and structural characterization helped to understand the mechanism of action in many biologic systems. Plant lectins have been fundamental in human immunological studies because some of them are mitogenic/activating to lymphocytes. Understanding the molecular basis of lectin-carbohydrate interactions and of the intracellular signalling evoked holds promise for the design of novel drugs for the treatment of infectious, inflammatory and malignant diseases. It may also be of help for the structural and functional investigation of glycoconjugates and their changes during physiological and pathological processes.