Potentiation of human alpha4beta2 neuronal nicotinic receptors by a Flustra foliacea metabolite

The effects of various Flustra foliacea metabolites on different types of human neuronal nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus oocytes were investigated. Whereas most of the compounds tested had a small blocking effect, one of them, deformylflustrabromine, selectively increased the current obtained in alpha4beta2 receptors when co-applied with acetylcholine (ACh). The current increase was reversible and concentration-dependent. This potentiating effect was still present at saturating concentrations of acetylcholine, and no changes in single-channel conductance or reversal potential were observed, thus suggesting a modification in the gating of alpha4beta2 receptors. Dwell time analysis of single channel records indicates that the mechanism of action of deformylflustrabromine could be both an increase of the opening rate constant and a decrease of the closing rate constant on alpha4beta2 receptors. Thus, deformylflustrabromine may constitute an excellent starting point for the future development of related agents able to potentiate human neuronal nicotinic receptor function.     

Trypanosoma cruzi exhibits inter- and intra-strain heterogeneity in molecular karyotype and chromosomal gene location

Molecular karyotypes of 6 strains and 6 clones of Trypanosoma cruzi were determined using orthogonal-field-alternation gel electrophoresis. At least 15 different chromosome-sized DNA molecules, ranging in size from less than 200 kilobase pairs to greater than 2000 kilobase pairs, were resolved for each of the isolates examined. Many of the bands were present in different relative intensities suggesting that the number of individual chromosomes per organism may be considerably higher. Significant inter- and intra-strain differences in molecular karyotype and in the chromosomal locations of the genes for the spliced leader, tubulins, 5S ribosomal RNA and a heat shock protein were found. These marked chromosomal differences among T. cruzi strains and clones may be related to the high degree of phenotypic heterogeneity previously found in this parasite.     

Lack of chemopreventive efficacy of DL-selenomethionine in colon carcinogenesis

Epidemiologic observations and laboratory research have suggested that dietary selenium reduces the risk of colon cancer. Selenium-enriched brewer's yeast as a dietary supplement reduces the incidence of and mortality from cancer of the colon in humans. It is not clear whether the observed inhibitory effect is due to selenomethionine, or to other forms of selenium, or to a mixture of the selenium compounds present in selenium-enriched brewer's yeast. Therefore, bioassay described in this study examined the chemopreventive efficacy of 10 and 15 ppm selenomethionine, equivalent to 3.6 and 5.4 ppm as selenium, against azoxymethane (AOM)-induced colon carcinogenesis. At five weeks of age, groups of male F344 rats were fed diets containing 0 (control diet), 10 or 15 ppm selenomethionine. At seven and eight weeks of age, all rats except those in vehicle-treated groups received s.c. injections of AOM at a dose rate of 15 mg/kg body wt. The rats were maintained on their respective diets for 52 weeks and were then sacrificed. Colon tumors were processed and evaluated histopathologically. Colon tumor incidence and multiplicity were analyzed statistically. No obvious toxic effects were observed following dietary administration of 10 or 15 ppm selenomethionine as indicated by body weight gain. Administration of 10 or 15 ppm selenomethionine had no significant effect on colon tumor incidence and multiplicity. This study suggests that i) selenomethionine lacks chemopreventive efficacy against AOM-induced colon carcinogenesis and ii) other forms of selenium or a mixture of selenium compounds present in selenium-enriched brewer's yeast need to be evaluated for their chemopreventive efficacy.     

Alterations of pancreatic hepatocytes in rats exposed to carcinogens.

In this study, acute and chronic responses of pancreatic hepatocytes induced in F-344 rats by copper depletion-repletion protocol to certain hepatocarcinogens were examined. Administration of a single dose of tannic acid (subcutaneous), aflatoxin B1 (gavage), or lasiocarpine (intraperitoneally) caused characteristic nucleolar segregation in parenchymal cells of liver as well as in pancreatic hepatocytes. Chronic dietary administration of 2-acetylaminofluorene (0.025%) for 12 to 32 weeks led to the development of glutathione S-transferase-P-positive pancreatic hepatocytes in the pancreas. In addition, oval cell proliferation was observed in close association with pancreatic hepatocytes, but not in other areas of pancreas containing residual acinar cells. Oval cells in the pancreas and in the liver that developed in rats after chronic 2-acetylaminofluorene treatment and pancreatic duct cells stained positively with rat liver oval cell marker OV-6 antibodies by immunoperoxidase. These findings indicate that pancreatic hepatocytes respond to carcinogens in a fashion similar to parenchymal cells of liver.     

A method to reduce glutathione peroxidase levels in primary endothelial cell cultures

The purpose of this study was to develop culture conditions that would reduce glutathione peroxidase activity in bovine mammary endothelial cells. Conditions of reduce glutathione peroxidase activity were produced in vitro by culturing cells in selenium-deficient media. Low selenium levels were achieved by reducing serum concentrations; however, levels of essential growth factors also were reduced by this method. Therefore, cell proliferation was promoted by supplementation with combinations of defined serum components including insulin, transferrin, linoleic acid, bovine brain extract, and human epidermal growth factor. Out of seven different formulas tested, F12K medium containing 2% fetal bovine serum, insulin, transferrin, and linoleic acid was found to be conducive for cell proliferation. Upon confluence, endothelial cells cultured under these conditions consistently displayed short passage rates, consistent cell numbers, and classic cobblestone morphology when grown in the presence or absence of supplemental selenium. Additionally, these cells retained typical endothelial cell characteristics such as uptake of 1,1-dioctadecyl-3,3,3,3-tetramethylindo-carb ocyanine perchlorate acetylated low-density lipoprotein and the expression of cell adhesion molecules and von Willebrand Factor.     

Absence of HTLV I from New Zealand

Sera from 1,943 individuals from Auckland, New Zealand, were tested for the presence of serum antibodies to human T cell lymphotropic virus I (HTLV I), mainly with an enzyme-linked immunosorbent assay (ELISA) with cell extracts as target antigen. The individuals tested were blood donors and mostly Caucasian, but included indigenous Maoris and representatives of several groups of Pacific islanders now resident in New Zealand. Also included were 37 patients with various hematological malignancies, including seven with T cell leukemias. Although 1% of samples were positive by ELISA, none of these were confirmed as positives by Western blotting. On the basis of these results we consider that it is unlikely that HTLV I infection occurs in Auckland; however, we cannot exclude the possibility that pockets of virus infection may occur in other parts of New Zealand or the South Pacific.     

Genotoxicity of naturally occurring indole compounds: correlation between covalent DNA binding and other genotoxicity tests

3-Methylindole (3MI), melatonin (Mel), serotonin (Ser), and tryptamine (Tryp) were evaluated in vitro for their potential to induce DNA adducts, DNA strand breaks, chromosomal aberrations (Abs), inhibition of DNA synthesis, and mutations. All compounds produced DNA adducts in calf thymus DNA in the presence of rat liver S9. In cultured rat hepatocytes, all produced DNA adducts but none induced DNA strand breaks. In Chinese hamster ovary cells, 3MI and Mel produced DNA adducts, Abs, and inhibition of DNA synthesis with and without S9, except that Mel without S9 did not form adducts. Ser formed DNA adducts, was an equivocal Abs inducer, and suppressed DNA synthesis. Tryp induced neither adducts nor Abs, but did suppress DNA synthesis with S9. Ser and Tryp were less cytotoxic than 3MI and Mel. Mel, Ser, and Tryp failed to induce mutations in Salmonella and E. coli strains with or without S9. 3MI and Mel produced DNA adducts but not mutations in Salmonella TA100 with S9. 3MI and its metabolite indole 3-carbinol also did not induce mutations in a shuttle vector system in human cells. The lack of correlation between DNA adducts and other genotoxicity endpoints for these indole compounds may be due to the higher sensitivity of the (32)P-postlabeling adduct assay or it may indicate that the indole-DNA adducts per se are not mutagenic and are not able to induce strand breaks or alkali-labile lesions. The indole-induced Abs may result from cytotoxicity and suppression of DNA synthesis with minimal if any contribution from DNA adducts.     

Presenting characteristics,comorbidities, and outcomes of patients coinfected with COVID-19 and Mycoplasma pneumoniae in the USA

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is spreading at a rapid pace, and the World Health Organization declared it as pandemic on 11 March 2020. Mycoplasma pneumoniae is an "atypical" bacterial pathogen commonly known to cause respiratory illness in humans. The coinfection from SARS-CoV-2 and mycoplasma pneumonia is rarely reported in the literature to the best of our knowledge. We present a study in which 6 of 350 patients confirmed with COVID-19 were also diagnosed with M. pneumoniae infection. In this study, we described the clinical characteristics of patients with coinfection. Common symptoms at the onset of illness included fever (six [100%] patients); five (83.3%) patients had a cough, shortness of breath, and fatigue. The other symptoms were myalgia (66.6%), gastrointestinal symptoms (33.3%-50%), and altered mental status (16.7%). The laboratory parameters include lymphopenia, elevated erythrocyte sedimentation rate, C-reactive protein, lactate dehydrogenase, interleukin-6, serum ferritin, and D-dimer in all six (100%) patients. The chest X-ray at presentation showed bilateral infiltrates in all the patients (100%). We also described electrocardiogram findings, complications, and treatment during hospitalization in detail. One patient died during the hospital course.     

Genetic evidence on the origins of Indian caste populations

The origins and affinities of the approximately 1 billion people living on the subcontinent of India have long been contested. This is owing, in part, to the many different waves of immigrants that have influenced the genetic structure of India. In the most recent of these waves, Indo-European-speaking people from West Eurasia entered India from the Northwest and diffused throughout the subcontinent. They purportedly admixed with or displaced indigenous Dravidic-speaking populations. Subsequently they may have established the Hindu caste system and placed themselves primarily in castes of higher rank. To explore the impact of West Eurasians on contemporary Indian caste populations, we compared mtDNA (400 bp of hypervariable region 1 and 14 restriction site polymorphisms) and Y-chromosome (20 biallelic polymorphisms and 5 short tandem repeats) variation in approximately 265 males from eight castes of different rank to approximately 750 Africans, Asians, Europeans, and other Indians. For maternally inherited mtDNA, each caste is most similar to Asians. However, 20%-30% of Indian mtDNA haplotypes belong to West Eurasian haplogroups, and the frequency of these haplotypes is proportional to caste rank, the highest frequency of West Eurasian haplotypes being found in the upper castes. In contrast, for paternally inherited Y-chromosome variation each caste is more similar to Europeans than to Asians. Moreover, the affinity to Europeans is proportionate to caste rank, the upper castes being most similar to Europeans, particularly East Europeans. These findings are consistent with greater West Eurasian male admixture with castes of higher rank. Nevertheless, the mitochondrial genome and the Y chromosome each represents only a single haploid locus and is more susceptible to large stochastic variation, bottlenecks, and selective sweeps. Thus, to increase the power of our analysis, we assayed 40 independent, biparentally inherited autosomal loci (1 LINE-1 and 39 Alu elements) in all of the caste and continental populations (approximately 600 individuals). Analysis of these data demonstrated that the upper castes have a higher affinity to Europeans than to Asians, and the upper castes are significantly more similar to Europeans than are the lower castes. Collectively, all five datasets show a trend toward upper castes being more similar to Europeans, whereas lower castes are more similar to Asians. We conclude that Indian castes are most likely to be of proto-Asian origin with West Eurasian admixture resulting in rank-related and sex-specific differences in the genetic affinities of castes to Asians and Europeans.     

Copolymer effects on microglia and T cells in the central nervous system of humanized mice

The random amino acid copolymers FYAK and VWAK ameliorate EAE in a humanized mouse model expressing both a human transgenic myelin basic protein (MBP)85-99-specific T cell receptor and HLA-DR2. Here we show that microglia isolated from the central nervous system (CNS) of humanized mice with EAE induced by MBP85-99 and treated with these copolymers had reduced expression of HLA-DR, and thus reduced capacity to present MBP85-99 and activate transgenic T cells. In vitro microglia up-regulated empty HLA-DR2 upon activation with GM-CSF with or without LPS or IFN-gamma, but not with IL-4 or IL-10. Correspondingly, gene chip arrays showed that the CNS of untreated and YFAK-treated mice differentially expressed pro- and anti-inflammatory molecules during MBP85-99-induced EAE. Interestingly, microglia expressed the full-length gammabeta and alphabeta subunits of the tetrameric adaptor protein complexes AP-1 and AP-2 respectively, but after treatment with GM-CSF these complexes were cleaved, as had been found in immature dendritic cells derived from bone marrow. Strikingly, in vivo the perivascular lymphocyte infiltration seen in untreated mice immunized with MBP85-99 was composed of equal numbers of hVbeta2+ MPB85-99-specific transgenic and hVbeta2- endogenous T cells, while the much smaller infiltration seen after treatment with YFAK was composed predominantly of hVbeta2- endogenous T cells.