Assessment of metals content of widely used traditional toothbrushes in Addis Ababa, Ethiopia

ABSTRACT. Traditional toothbrushes are used by the vast majority of people who cannot afford to buy the commercial toothbrush and toothpaste. The traditional toothbrushes are generally obtained from any slim woody part of a toothbrush tree. The main purpose of this study was to determine selected metals (Ca, Fe, Mg, Al, Cu, Cr, Ni, Zn, Mn, Pb, and Cd) in traditional toothbrushes obtained from three plants including Ligustrum vulgare L., Phoenix reclinata and Olea africana, which are extensively used in Addis Ababa, Ethiopia, by using microwave plasma-atomic emission spectroscopy (MP-AES) after wet digestion. Recoveries of the metals in spiked samples varied from 90.4–107%. The overall mean concentrations determined (mg/kg, dry weight) were in the ranges of Ca (4267–36514) > Fe (131–318) > Al (81.6 –224) > Mg (45.6–122) > Zn (27.2–175) > Mn (20.1–29) > Cu (6.6–20.3) > Cr (6.7–8.9) > Ni (2.6–7.9). Analysis of variance at 95% indicated significant differences in the metals’ contents of three toothbrushes. The results indicated that the selected traditional toothbrushes are good sources of essential metals and free from Pb and Cd. Therefore, the investigated Ethiopian traditional toothbrushes are found to be safe for human use.                     KEY WORDS: Metal contents, Traditional toothbrushes, Wild privet (Ligustrum vulgare), Wild date palm (Phoenix reclinata), African wild olive (Olea africana), Ethiopia   Bull. Chem. Soc. Ethiop. 2021, 35(2), 257-272. DOI: https://dx.doi.org/10.4314/bcse.v35i2.

Chimeric Anti-Staphylococcal Enterotoxin B Antibodies and Lovastatin Act Synergistically to Provide In Vivo Protection against Lethal Doses of SEB

Staphylococcal enterotoxin B (SEB) is one of a family of toxins secreted by Staphylococcus aureus that act as superantigens, activating a large fraction of the T-cell population and inducing production of high levels of inflammatory cytokines that can cause toxic shock syndrome (TSS) and death. Extracellular engagement of the TCR of T-cells and class II MHC of antigen presenting cells by SEB triggers the activation of many intracellular signaling processes. We engineered chimeric antibodies to block the extracellular engagement of cellular receptors by SEB and used a statin to inhibit intracellular signaling. Chimeric human-mouse antibodies directed against different neutralizing epitopes of SEB synergistically inhibited its activation of human T-cells in vitro. In the in vivo model of lethal toxic shock syndrome (TSS) in HLA-DR3 transgenic mice, two of these antibodies conferred significant partial protection when administered individually, but offered complete protection in a synergistic manner when given together. Similarly, in vivo, lovastatin alone conferred only partial protection from TSS similar to single anti-SEB antibodies. However, used in combination with one chimeric neutralizing anti-SEB antibody, lovastatin provided complete protection against lethal TSS in HLA-DR3 transgenic mice. These experiments demonstrate that in vivo protection against lethal doses of SEB can be achieved by a statin of proven clinical safety and chimeric human-mouse antibodies, agents now widely used and known to be of low immunogenicity in human hosts

Genetic Patterns of Domestication in Pigeonpea (Cajanus cajan (L.) Millsp.) and Wild Cajanus Relatives

Pigeonpea (Cajanus cajan) is an annual or short-lived perennial food legume of acute regional importance, providing significant protein to the human diet in less developed regions of Asia and Africa. Due to its narrow genetic base, pigeonpea improvement is increasingly reliant on introgression of valuable traits from wild forms, a practice that would benefit from knowledge of its domestication history and relationships to wild species. Here we use 752 single nucleotide polymorphisms (SNPs) derived from 670 low copy orthologous genes to clarify the evolutionary history of pigeonpea (79 accessions) and its wild relatives (31 accessions). We identified three well-supported lineages that are geographically clustered and congruent with previous nuclear and plastid sequence-based phylogenies. Among all species analyzed Cajanus cajanifolius is the most probable progenitor of cultivated pigeonpea. Multiple lines of evidence suggest recent gene flow between cultivated and non-cultivated forms, as well as historical gene flow between diverged but sympatric species. Evidence supports that primary domestication occurred in India, with a second and more recent nested population bottleneck focused in tropical regions that is the likely consequence of pigeonpea breeding. We find abundant allelic variation and genetic diversity among the wild relatives, with the exception of wild species from Australia for which we report a third bottleneck unrelated to domestication within India. Domesticated C. cajan possess 75% less allelic diversity than the progenitor clade of wild Indian species, indicating a severe “domestication bottleneck” during pigeonpea domestication

Emergence of high drug resistant bacterial isolates from patients with health care associated infections at Jimma University medical center: a cross sectional study

Background: The rates of resistant microorganisms which complicate the management of healthcare associated infections (HAIs) are increasing worldwide and getting more serious in developing countries. The objective of this study was to describe microbiological features and resistance profiles of bacterial pathogens of HAIs in Jimma University Medical Center (JUMC) in Ethiopia.Methods: Institution based cross sectional study was carried out on hospitalized patients from May to September, 2016 in JUMC. Different clinical specimens were collected from patients who were suspected to hospital acquired infections. The specimens were processed to identify bacterial etiologies following standard microbiological methods. Antibacterial susceptibility was determined in vitro by Kirby-Bauer disk diffusion method following Clinical and Laboratory Standards Institute guidelines.Results: Overall, 126 bacterial etiologies were isolated from 118 patients who had HAIs. Of these, 100 (79.4%) were gram negative and the remaining were gram positive. The most common isolates were Escherichia coli 31(24.6%), Klebsiella species 30(23.8%) and Staphylococcus aureus 26 (20.6%). Of 126 bacterial isolates, 38 (30.2%), 52 (41.3%), and 24 (19%) were multidrug-resistant (MDR, resistant to at least one agent in three or more antimicrobial categories), extensively drug resistant (XDR, resistant to at least one agent in all but two or fewer antimicrobial categories (i.e. bacterial isolates remain susceptible to only one or two categories), pan-drug resistant (PDR, resistant to all antibiotic classes) respectively. More than half of isolated gram-negative rods (51%) were positive for extended spectrum beta-lactamase (ESBL) and/or AmpC; and 25% of gram negative isolates were also resistant to carbapenem antibiotics.Conclusions: The pattern of drug resistant bacteria in patients with healthcare associated infection at JUMC is alarming. This calls for coordinated efforts from all stakeholders to prevent HAIs and drug resistance in the study setting

Occurrence of extended spectrum beta (β)-lactamases in multi-drug resistant Escherichia coli isolated from a clinical setting in Jimma University Specialized Hospital, Jimma, southwest Ethiopia.

Introduction: Resistance to antibiotics has grave consequences leading to treatment failure and increased health care costs. This public health risk has become a global problem with some countries like Ethiopia seriously affected. Members of the family enterobacteriaceae, including E. coli, are among the most important human pathogens accounting for the majority of bacterial strains isolated from clinical patient samples. Moreover, there is insufficient data regarding Extended-spectrum Beta-lactamase (ESBL) prevalence among Escherichia coli strains from Ethiopia. Thus, the objective was to determine the production of ESBL among clinical isolates and assess the in vitro susceptibility of the E.coli to the routinely used selected antibiotics.Methods: We collected a total of 359 clinical specimens (56 urine, 116 sputum, 72 stool and 15 wound swabs) from in- and outpatients at Jimma University Specialised Hospital, Jimma zone, southwest Ethiopia.Results: E. coli was isolated from 67 (18.66%) clinical specimens, of which 24 (36%) isolates were ESBL producers. The resistance pattern to the tested antibiotics was: penicillin (97%), amoxacillin and ampicillin (86.6% each), tetracycline (73.1%), amoxacillinclavulanate (70.1%), co-trimoxazole (56.7%), chloramphenicol (35.8%), ciprofloxacine (20.9%), norfloxacine (16.4%), cefotaxime (9%), ceftazidime (6%), gentamicin (3%). All the isolates tested showed resistance to two or more drugs, and were considered to be multi-drug resistant.Conclusion: A higher rate (46%) of ESBL production and multi-drug resistance was seen among isolates from inpatients as compared to outpatients (33%) at the hospital.Key words: Antibiotics, Multi-drug resistance, Extended Spectrum Beta-Lactamase, Jimma University Specialized Hospital, Ethiopi

Potent Neutralization of Staphylococcal Enterotoxin B by Synergistic Action of Chimeric Antibodies▿

Staphylococcal enterotoxin B (SEB), a shock-inducing exotoxin synthesized by Staphylococcus aureus, is an important cause of food poisoning and is a class B bioterrorism agent. SEB mediates antigen-independent activation of a major subset of the T-cell population by cross-linking T-cell receptors (TCRs) with class II major histocompatibility complex (MHC-II) molecules of antigen-presenting cells, resulting in the induction of antigen independent proliferation and cytokine secretion by a significant fraction of the T-cell population. Neutralizing antibodies inhibit SEB-mediated T-cell activation by blocking the toxin's interaction with the TCR or MHC-II and provide protection against the debilitating effects of this superantigen. We derived and searched a set of monoclonal mouse anti-SEB antibodies to identify neutralizing anti-SEB antibodies that bind to different sites on the toxin. A pair of non-cross-reactive, neutralizing anti-SEB monoclonal antibodies (MAbs) was found, and a combination of these antibodies inhibited SEB-induced T-cell proliferation in a synergistic rather than merely additive manner. In order to engineer antibodies more suitable than mouse MAbs for use in humans, the genes encoding the VL and VH gene segments of a synergistically acting pair of mouse MAbs were grafted, respectively, onto genes encoding the constant regions of human Igκ and human IgG1, transfected into mammalian cells, and used to generate chimeric versions of these antibodies that had affinity and neutralization profiles essentially identical to their mouse counterparts. When tested in cultures of human peripheral blood mononuclear cells or splenocytes derived from HLA-DR3 transgenic mice, the chimeric human-mouse antibodies synergistically neutralized SEB-induced T-cell activation and cytokine production

Synergistic neutralization /inhibition of SEB-mediated T-cell activation by a combination of anti-SEB antibody and lovastatin.

<p>(<b>A</b>) Anti-SEB Ch 82 M and lovastatin inhibit SEB action in BALB/c splenocytes. BALB/c splenocytes were cultured as outlined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0027203#s4" target="_blank">materials and methods</a> with the following additives: Medium alone, SEB alone, 100 ng/ml SEB; Hu IgG1κ+SEB, 10 µg/ml Human IgG1κ+100 ng/ml of SEB; Ch 82 M+SEB, 10 µg/ml chimeric anti-SEB 82 M+100 ng/ml SEB; Lova+SEB, 2.5 µM lovastatin+100 ng/ml SEB; Ch 82 M+Lova+SEB, 10 µg /ml chimeric anti-SEB 82 M+2.5 µM lovastatin+100 ng/ml SEB. Each bar represents the means ± s.d. of triplicate measurements, and the data shown are representative of two or more independent experiments. The combination of Ch 82 M+lovastatin was significantly more inhibitory than either agent alone (P<0.01). (<b>B</b>) Anti-SEB Ch 82 M and lovastatin inhibit SEB action in HLA-DR3 transgenic mice splenocytes. HLA-DR3 transgenic mice splenocytes were cultured as outlined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0027203#s4" target="_blank">materials and methods</a> with the following additives: Medium alone, SEB alone, 10 ng/ml SEB; HuIgG1κ+SEB, 10 µg/ml Human IgG1κ+10 ng/ml of SEB; Ch 82 M+SEB, 10 µg/ml chimeric anti-SEB 82 M+10 ng/ml SEB; Lova+SEB, 2.5 µM lovastatin+10 ng/ml SEB; Ch 82 M+Lova+SEB, 10 µg/ml chimeric anti-SEB 82 M+2.5 µM lovastatin+10 ng/ml SEB. Each bar represents the means ± s.d. of triplicate measurements, and the data shown are representative of two or more independent experiments. The combination of Ch 82 M and lovastatin was significantly more inhibitory than either agent alone (P<0.01). (<b>C</b>) Anti-SEB Ch 82 M and lovastatin inhibit SEB action in human PBMCs. PBMCs were cultured as outlined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0027203#s4" target="_blank">materials and methods</a> with the following additives: Medium alone, SEB alone, 1 ng/ml SEB; HuIgG1κ+SEB, 10 µg/ml Human IgG1κ+1 ng/ml of SEB; Ch 82 M+SEB, 10 µg/ml chimeric anti-SEB 82 M+1 ng/ml SEB; Lova+SEB, 2.5 µM lovastatin+1 ng/ml SEB; Ch 82 M+Lova+SEB, 10 µg/ml chimeric anti-SEB 82 M+2.5 µM lovastatin+1 ng/ml SEB. Each bar represents the means ± s.d. of triplicate measurements, and the data shown are representative of two or more independent experiments. The combination of Ch 82 M and lovastatin was significantly more inhibitory than either agent alone (P<0.01).</p