LDEF impact craters formed by carbon-rich impactors: A preliminary report

Two impact craters found in Al from the Long Duration Exposure Facility (LDEF) experiment tray have residues concentrated in the bottoms, along the walls, and on top of overturned rims. Analyses indicate a 'chondritic' compositional signature (Si, S, Ca, Fe, Mg, and Ni) for the bulk residue. In one crater (number 74), round to irregular silicate grains are overlain by carbon. In addition, carbon also partially covers the crater walls, the top of the raised overturned rim, and extends outward from the crater. The second crater (number 31) also contains carbon with similar distribution in and about the crater, although the silicate residue appears to be glassy. Silver, I, K, and F (possibly some of the Ca, S, and Cl) appear to be contaminants as well as analyzed aromatic carbonaceous species associated with the raised rim and the area surrounding the crater. The origin of the impactors is assumed to be extraterrestrial. The existence of impactor residue in two craters implies impact velocities less than or equal to 6 km, based on experimental hypervelocity studies

Rituximab as an immunosuppressant in antineutrophil cytoplasmic antibody-associated vasculitis

Rituximab has been used in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) since 2003. Our objective was to describe outcomes and adverse events following rituximab since that time in an inception cohort

Concentrations of thiocyanate and goitrin in human plasma, their precursor concentrations in brassica vegetables, and associated potential risk for hypothyroidism

Brassica vegetables are common components of the diet and have beneficial as well as potentially adverse health effects. Following enzymatic breakdown, some glucosinolates in brassica vegetables produce sulforaphane, phenethyl, and indolylic isothiocyanates that possess anticarcinogenic activity. In contrast, progoitrin and indolylic glucosinolates degrade to goitrin and thiocyanate, respectively, and may decrease thyroid hormone production. Radioiodine uptake to the thyroid is inhibited by 194 μmol of goitrin, but not by 77 μmol of goitrin. Collards, Brussels sprouts, and some Russian kale (Brassica napus) contain sufficient goitrin to potentially decrease iodine uptake by the thyroid. However, turnip tops, commercial broccoli, broccoli rabe, and kale belonging to Brassica oleracae contain less than 10 μmol of goitrin per 100-g serving and can be considered of minimal risk. Using sulforaphane plasma levels following glucoraphanin ingestion as a surrogate for thiocyanate plasma concentrations after indole glucosinolate ingestion, the maximum thiocyanate contribution from indole glucosinolate degradation is estimated to be 10 μM, which is significantly lower than background plasma thiocyanate concentrations (40–69 μM). Thiocyanate generated from consumption of indole glucosinolate can be assumed to have minimal adverse risks for thyroid health

Biology and chemistry of an Umbravirus like 2989 bp single stranded RNA as a possible causal agent for Opuntia stunting disease (engrosamiento de cladodios)-A Review.

Perhaps the most economically important disease of Opuntia ficus indica fruit cacti in Mexico is the “engrosamiento de cladodios” or macho disease. The symptoms of this disease, which has been suggested to be caused by a phytoplasma, are severe stunting of cladodes, flowers and fruits. In the mid-1980s this disease appeared in commercial cactus fruit orchards of D’Arrigo Bros near Gonzalez, California. It was performed more than 30 PCR-based tests for viruses as well as various extraction methods and polymerase chain reaction (PCR) tests for phytoplasmas but were unable to find any of the known viruses or mycoplasmas in the strongly symptomatic cactus with this disease. As almost all plant viruses go through a replication phase involving double stranded RNA (dsRNA), a dsRNA extraction was performed and a dsRNA species of about 600 bp identified. Then, reverse-transcribed the dsRNA, amplified the resultant cDNA by PCR, and cloned and sequenced the 600 bp fragment that were identified in symptomatic tissue. When this sequence was compared to translated DNA in the National Center for Biotechnology Information (NCBI) nucleotide data base (BLAST analysis) it was most similar to the Tobacco bushy top virus (E score of 2e-39), which is a single stranded RNA virus with no DNA intermediate. Primers made from this 630 bp fragment were used to extend this sequence to 2989 sequence. This sequence appears to be a full-length sequence with three open reading frames (ORF) and is shorter than the closest class of viruses, the Umbraviruses that can be spread by mechanical transmission and by aphids. It was not possible to transmit the virus or symptoms mechanically. Over a six-year period using traditional PCR, this virus was found in hundreds of symptomatic cacti but not in non-symptomatic pads. RT-PCR has found low levels of this virus on nonsymptomatic cladodes (3.7 fg) on a symptomatic plant and much higher concentrations (1x102 to 1x105 fg) on symptomatic cladodes from the same plant. Black bean aphids (Aphis Felker et al., 2019. JPACD (2019) 21:1-31 2 fabae), that are the vector for a closely related Umbravirus known as groundnut rosetta virus, have been routinely found on the unopened flowers of cactus. This Umbravirus was found in aphids feeding on symptomatic cladodes. As Umbraviruses cannot infect plants without a companion Luteovirus, that provides the protein coat for the Umbravirus, degenerate Luteovirus primers were used and a probable incomplete Luteovirus-like 4797 bp sequence was found on aphids feeding on symptomatic cactus. This Luteovirus was not found in Opuntia cladodes using PCR. A micro RNA assembly of six pooled symptomatic Opuntias did not find a contig that spanned the 4797 putative Luteovirus sequence, but some fragments as large as 44 bp were exact matches to the Luteovirus. As Umbraviruses occur throughout the plant but Luteoviruses only occur in the phloem, lower Luteovirus concentrations would be expected. Two successive one hour 60°C heat treatments eliminated these symptoms on new growth that was also PCR negative. A 5839 bp Potexvirus was found in some of these cladodes but its presence was not correlated with any symptoms. Similar symptomatic cacti in Italy, South Africa and Mexico should be examined with these primers and dsRNA to see if similar correlations between presence/absence of this fragment and symptomatic plants can be obtained. It is suggested that this disease be known as OSD (Opuntia Stunting Disease)

Maintenance of Tolerance by Regulation of Anti-myeloperoxidase B Cells

Anti-neutrophil cytoplasmic autoantibodies directed toward myeloperoxidase or proteinase 3 are detected in sera of patients with small vessel vasculitis and participate in the pathogenesis of this disease. Autoantibodies develop when self-reactive B cells escape the regulation that ensures self-tolerance. In this study, regulation of anti-myeloperoxidase B cells was examined in mice that express an anti-myeloperoxidase Vκ1C-Jκ5 light-chain transgene, which confers anti-myeloperoxidase specificity when combined with a variety of heavy chains. Vκ1C-Jκ5 transgenic mice have splenic anti-myeloperoxidase B cells but do not produce circulating anti-myeloperoxidase antibodies. Two groups of transgenic mice that differed by their relative dosage of the transgene were compared; high-copy mice had a mean relative transgene dosage of 1.92 compared with 1.02 in the low-copy mice. These mice exhibited a 90 and 60% decrease in mature follicular B cells, respectively. High-copy mice were characterized by a large population of anti-myeloperoxidase B cells, a preponderance of B-1 cells, and an increased percentage of apoptotic myeloperoxidase-binding B cells. Low-copy mice had similar changes in B cell phenotype with the exception of an expanded marginal zone population. B cells from low-copy mice but not high-copy mice produced anti-myeloperoxidase antibodies after stimulation with lipopolysaccharide. These results indicate that tolerance to myeloperoxidase is maintained by central and peripheral deletion and that some myeloperoxidase-binding B cells are positively selected into the marginal zone and B-1 B cell subsets. A defect in these regulatory pathways could result in autoimmune disease