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Sulfur is vital for primary and secondary metabolism in plant roots. To understand the molecular and morphogenetic changes associated with loss of this key macronutrient, we grew Arabidopsis (Arabidopsis thaliana) seedlings in low-sulfur conditions. These conditions induced a cascade of cellular events that converged to produce a profound intracellular phenotype defined by large cytoplasmic inclusions. The inclusions, termed low-sulfur Pox, show cell type- and developmental zone-specific localization. Transcriptome analysis suggested that low sulfur causes dysfunction of the glutathione/ascorbate cycle, which reduces flavonoids. Genetic and biochemical evidence indicated that low-sulfur Pox are the result of peroxidase-catalyzed oxidation of quercetin in roots grown under sulfur-depleted conditions. [ABSTRACT FROM AUTHOR]

Using a recently described polymerase chain reaction-based DNA typing method for Entamoeba histolytica and E. dispar, we investigated the genetic diversity of these species in a geographically restricted region of South Africa. Patterns were stable over time in the same infection, and, with few exceptions, infected family members carried the same strain. However, both species exhibited remarkable variation, with no 2 family groups being infected with the same strain of E. histolytica. Mixed infections were rare. The results indicate that this typing method will be useful in identifying epidemiological linkage between infections. [ABSTRACT FROM AUTHOR]

Studies infection and immunity mediated by the carbohydrate recognition domain (CRD) of the Entamoeba histolytica Gal/GalNAc lectin. Identification of CRD within the lectin heavy-subunit cysteine-rich region; Competition of CRD with the hepatocyte growth factor (HGF) for binding to the HGF receptor.

Four-week toxicity studies with the 21-aminosteroid tirilazad mesylate were conducted in Sprague-Dawley rats, beagle dogs, and cynomolgus monkeys to support development of the drug for use in various clinical syndromes of injury to the central nervous system of humans. As the immune system is Involved in many of the obvious side effects of glucocorticoids used currently for this indication, particular attention was directed to the lymphoid system; results were contrasted with similar data from studies with methylprednisolone, a classical glucocorticoid. Administration of tirilazad mesylate to rats, dogs and monkeys for 4 weeks had no effects at the highest doses tested on parameters assessed, including absolute peripheral blood lymphocyte counts, thymus or adrenal weights, circulating levels of cortisol, or lymphocyte proliferation response to phytohemagglutinin-P. Germinal centers in lymphoid tissues from dogs given high doses of tirilazad contained small numbers of macrophages with vacuolated cytoplasm but no other changes; lymphoid tissues in rats and monkeys given tirilazad were morphologically normal. Administration of methylprednisolone for a similar duration in rats and dogs at high dose levels was associated with increased death rates due to bacterial infections, markedly decreased peripheral blood lymphocyte counts and weights of thymus and adrenal glands, and prominent lymphoid atrophy as well as decreased circulating levels of cortisol. Female dogs infused for 10 days with a high dose of methylprednisolone had depression of the proliferation response of peripheral blood lymphocytes to phytohemagglutinin-P. [ABSTRACT FROM PUBLISHER]

The 170-kDa subunit of the galactose-inhibitable adherence lectin of Entamoeba histolytica mediates attachment to colonic mucins and host cells. The DNA fragment encoding the 170-kDa subunit was produced by polymerase chain reaction (PCR) and divided into four sections by restriction endonucleases. The third section (designated LC3, base pairs 2273–3397) encodes a cysteine-rich fusion protein that was recognized by adherence-inhibitory anti-lectin monoclonal antibodies and serum antibodies from 95% of subjects with amebic liver abscess. Immunization of gerbils with purified recombinant LC3-encoded protein (10 µg) with Titermax adjuvant elicited a high-titer serum anti-LC3 IgG antibody response and protective immunity against intrahepatic challenge with 0.5 'd7 106 virulent axenic trophozoites (strain HM1:IMSS; 71% vaccine efficacy, P < .01). In summary, a recombinant cysteine-rich portion of the 170-kDa lectin subunit was highly antigenic, immunogenic, and effectiveas a subunit vaccine in an experimental animal model of amebic liver abscess. [ABSTRACT FROM PUBLISHER]

The recognition of the Entamoeba histolytica galactose-inhibitable adherence lectin by antibodies was studied using sera obtained from subjects in South Africa with an amebic liver abscess or asymptomatically pathogenic or nonpathogenic E. histolytica infection and from uninfected regional controls. In addition, sera from healthy American controls or Americans known to be infected with other parasites were studied. Of the 95 sera containing antibodies to total parasite protein, 9596 demonstrated antibodies to the 170-kDa heavy subunit but not to the 35-kDa light lectin subunit. All sera (n = 253) were tested by ELISA for antibodies to lectin: 9996 from liver abscess patients and all 4 fromindividuals asymptomatically infected with pathogenic E. histolytica were positive; all from the 40 healthy American controls and the 29 infected with other parasites were negative (P < .01). The prevalence of serum anti-lectin antibodies was identical (2596) in asymptomatic South Africans with either a nonpathogenic infection or a negative stool culture for E. histolytica. Thus, the presence of serum antibodies to lectin seems to indicate current or prior invasive amebiasis or asymptomatic intestinal infection with pathogenic E. histolytica. [ABSTRACT FROM PUBLISHER]

Monoclonal antibodies (MAbs) directed against pathogen-specific epitopes of the galactose adhesin of Entamoeba histolytica were used in an ELISA to detect antigen from pathogenic E. histolytica. Single stool specimens from 74 patients in Bangladesh were used. The ELISA for pathogenic E. histolytica was positive in all 12 stool specimens with pathogenic amebae subsequently cultured, in no stool specimens with nonpathogenic E. histolytica and in 2 of 40 stools with other or no intestinal parasites detected. Specificity and sensitivity of the assay for pathogenic E. histolytica were 97% and 100%, respectively. These preliminary data offer promise for an ELISA using MAbs to the galactose adhesin as a rapid and sensitive means to detect the presence of pathogenic E. histolytica infection in stool specimens. [ABSTRACT FROM AUTHOR]