Involvement of motility and flagella in Bacillus cereus biofilm formation

Bacillus cereus is a food-borne pathogen and a frequent contaminant of food production plants. The persistence of this pathogen in various environments results from the formation of spores and of biofilms. To investigate the role of the B. cereus flagellar apparatus in biofilm formation, we constructed a non-flagellated mutant and a flagellated but non-motile mutant. Unexpectedly, we found that the presence of flagella decreased the adhesion of the bacterium to glass surfaces. We hypothesize that this decrease is a consequence of the flagella hindering a direct interaction between the bacterial cell wall and the surface. In contrast, in specific conditions, motility promotes biofilm formation. Our results suggest that motility could influence biofilm formation by three mechanisms. Motility is necessary for the bacteria to reach surfaces suitable for biofilm formation. In static conditions, reaching the air-liquid interface, where the biofilm forms, is a strong requirement, whereas in flow cells bacteria can have access to the bottom glass slide by sedimentation. Therefore, motility is important for biofilm formation in glass tubes and in microtitre plates, but not in flow cells. Motility also promotes recruitment of planktonic cells within the biofilm by allowing motile bacteria to invade the whole biofilm. Finally, motility is involved in the spreading of the biofilm on glass surfaces.

Molecular basis for group-specific activation of the virulence regulator PlcR by PapR heptapeptides

The transcriptional regulator PlcR and its cognate cell–cell signalling peptide PapR form a quorum-sensing system that controls the expression of extra-cellular virulence factors in various species of the Bacillus cereus group. PlcR and PapR alleles are clustered into four groups defining four pherotypes. However, the molecular basis for group specificity remains elusive, largely because the biologically relevant PapR form is not known. Here, we show that the in vivo active form of PapR is the C-terminal heptapeptide of the precursor, and not the pentapeptide, as previously suggested. Combining genetic complementation, anisotropy assays and structural analysis we provide a detailed functional and structural explanation for the group specificity of the PlcR–PapR quorum-sensing system. We further show that the C-terminal helix of the PlcR regulatory domain, specifically the 278 residue, in conjunction with the N-terminal residues of the PapR heptapeptide determines this system specificity. Variability in the specificity-encoding regions of plcR and papR genes suggests that selection and evolution of quorum-sensing systems play a major role in adaptation and ecology of Bacilli.

Development and field performance of a broad-spectrum nonviable asporogenic recombinant strain of Bacillus thuringiensis with greater potency and UV resistance

The main problems with Bacillus thuringiensis products for pest control are their often narrow activity spectrum, high sensitivity to UV degradation, and low cost effectiveness (high potency required). We constructed a sporulation-deficient SigK(-) B. thuringiensis strain that expressed a chimeric cry1C/Ab gene, the product of which had high activity against various lepidopteran pests, including Spodoptera littoralis (Egyptian cotton leaf worm) and Spodoptera exigua (lesser [beet] armyworm), which are not readily controlled by other Cry delta-endotoxins. The SigK(-) host strain carried the cry1Ac gene, the product of which is highly active against the larvae of the major pests Ostrinia nubilalis (European corn borer) and Heliothis virescens (tobacco budworm). This new strain had greater potency and a broader activity spectrum than the parent strain. The crystals produced by the asporogenic strain remained encapsulated within the cells, which protected them from UV degradation. The cry1C/Ab gene was introduced into the B. thuringiensis host via a site-specific recombination vector so that unwanted DNA was eliminated. Therefore, the final construct contained no sequences of non-B. thuringiensis origin. As the recombinant strain is a mutant blocked at late sporulation, it does not produce viable spores and therefore cannot compete with wild-type B. thuringiensis strains in the environment. It is thus a very safe biopesticide. In field trials, this new recombinant strain protected cabbage and broccoli against a pest complex under natural infestation conditions.

Ultradian variations in sensitivity of rat aorta rings to noradrenaline

The in vitro sensitivity of the rat aorta to the vasoconstrictor effect of noradrenaline was found to vary according to the time the animals were killed, with a minimum at 10:00 h and a maximum at 16:00 h. This ultradian rhythm was not influenced by the presence of the endothelium but was modified by some, as yet unidentified, circulating factor(s). The results also strongly suggested an ultradian rhythm of in vitro sensitivity to the beta-adrenoceptor agonists, salbutamol and isoprenaline. This rhythm appears to be opposite to that for the sensitivity of aortic alpha-adrenoceptors to stimulation. In conclusion, our results demonstrate that the regulation of aortic tone follows an ultradian rhythm.

Sample preparation for beta-exotoxin determination in Bacillus thuringiensis cultures by reversed-phase high-performance liquid chromatography

Beta-exotoxin is a nucleotide analogue produced by the entomopathogenic bacterium Bacillus thuringiensis. We have defined two new HPLC procedures for quantification of this exotoxin in culture supernatants of B. thuringiensis grown in poor or rich medium. The sample is prepared either by precipitation in solvent or by solid-phase extraction. Solvent precipitation is achieved treating the sample with acetone and acetonitrile. Solid-phase extraction is performed with a C18 and an anion-exchange cartridge. Reversed-phase HPLC with gradient elution of the prepared samples gives a limit of quantitation of 2 microg/ml for samples prepared by solvent precipitation and of 0.3 microg/ml for samples prepared by solid-phase extraction.

Removal of intrauterine devices with missing tails during early pregnancy

During a 70-month period, CO2 hysteroscopy was carried out on 52 pregnant women wearing IUDs with retracted tails. Ultrasonography was done prior to hysteroscopy to determine the size of the gestational sac and the site of the device. Successful removal of the device occurred in 46 cases. The technique, the findings of the study, and the limitations of the procedure are described.

Histopathological effects of silicone rubber 'Ovabloc' on the human fallopian tube

OBJECTIVE

To study the histopathological effects of silicone rubber on the human fallopian tube.

METHODS

A prospective longitudinal study at Benha University Hospital and Boulak Eldakrour General Hospital, Egypt. Nine patients who were on the waiting list for hysterectomy and requested postponing of their operation for personal reasons.

RESULTS

Our results suggest that silicone rubber induces histopathological changes in the form of ciliary loss and intracellular changes.

CONCLUSIONS

These effects tend to increase with the increase of the duration of tubal plugging and are best seen by electron microscopy.

Diurnal rhythms in the synthesis and release of haemolymph proteins in the crustacean Isopoda, Porcellio dilatatus (Brandt), with special reference to vitellogenin

Synthesis and release of vitellogenin in the crustacean Isopoda, Porcellio dilatatus, were maximal during premolt. At that time, diurnal variations occurred in the haemolymph protein level and in the synthesis and release of vitellogenin and other proteins in the haemolymph. The pattern of variations was always identical and bimodal: the minima were at dusk and at dawn when the maxima occurred in the middle of the day and of the night. These variations were highly significant, and the diurnal means were significantly higher than the nocturnal means.

Rythme nycthéméral de la synthèse protéique ovarienne chez le crustacé oniscoïde Porcellio dilatatus Brandt et rôle du protocérébron

In Porcellio dilatatus, ovarian protein synthesis shows a diurnal rhythm with a maximum at the onset of night. Sham-operated females maintain this rhythm, which disappears after the ablation of the central part of the protocerebron. This operation also induces a decrease in the mean level of ovarian protein synthesis. Protocerebron implantation, before the removal of the brain, does not prevent the loss of that rhythm but maintains the same synthesis level as in sham-operated animals. Control of the ovarian protein synthesis rhythm by the central nervous system and the existence of a stimulating neurohormone for that synthesis are discussed.

A quartet pollen phenotype identified in a population of Brassica interspecific hybrids shows incomplete penetrance and variable response to temperature

Quartet pollen, where pollen grains remain attached to each other post-meiosis, is useful for tetrad analysis, crossover assessment and centromere mapping. We observed the quartet pollen phenotype for the first time in the agriculturally significant Brassica genus, in an experimental population of allohexaploid Brassica hybrids derived from the cross (Brassica napus × B. carinata) × B. juncea followed by two self-pollination generations. Quartet pollen production was assessed in 144 genotypes under glasshouse conditions, following which a set of 16 genotypes were selected to further investigate the effect of environment (warm: 25 °C and cold: 10 °C temperatures) on quartet pollen production in growth cabinets. Under glasshouse phenotyping conditions, only 92 out of 144 genotypes produced enough pollen to score: of these, 30 did not produce any observable quartet pollen, while 62 genotypes produced quartet pollen at varying frequencies. Quartet pollen production appeared quantitative and did not clearly fall into phenotypic or qualitative categories indicative of major gene expression. No consistent effect of temperature on quartet pollen production was identified, with some genotypes producing more and some producing less quartet pollen under different temperature treatments. The genetic heterogeneity and frequent pollen infertility of this population prevents strong conclusions being made. However, it is clear that the quartet phenotype in this Brassica population does not show complete penetrance and shows variable (likely genotype-specific) response to temperature stress. In future, identification of quartet phenotypes in Brassica would perhaps best be carried out via screening of diploid (e.g. B. rapa) TILLING populations.

406 SARS-CoV-2 Vaccination Modelling for Safe Surgery to Save Lives: Data from an International Prospective Cohort Study

Aim

Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling.

Method

The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18–49, 50–69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty.

Results

NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year.

Conclusions

As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population.

Evaluating comparative effectiveness of pembrolizumab-based therapy versus chemotherapy in treatment of gastric carcinoma: a systematic review and meta-analysis of randomized controlled trials

Gastric cancer, especially cancer of the gastro-esophageal junction, ranks among the first five cancers in the world with the highest mortality rates. It has poor survival rates for the advanced stages. Traditional chemotherapy, while standard, often results in significant side effects and limited efficacy. The objective of this meta-analysis and systemic review is to ascertain if pembrolizumab-based therapies for advanced gastric cancer are more effective and safer than standard chemotherapy. The focus consisted of RCTs with adults suffering from gastric carcinoma who received pembrolizumab every 3 weeks (200 mg) intra-related dose or with at least comparable chemotherapy regimen. Outcomes assessed are as follows: overall survival (OS), progression-free survival (PFS), and objective response rate (ORR). All potential sources regarding the search of outcome measures were applied: Google Scholar, Scopus, PubMed, and Cochrane library, and last search in June 2024 was carried out. Out of 568 articles screened, four RCTs comprising 2,831 patients met the inclusion criteria. Analysis indicated that pembrolizumab alone did not significantly improve OS compared to chemotherapy (HR 0.87). However, when combined with chemotherapy, pembrolizumab dramatically enhanced OS (HR 0.80) and PFS (HR 0.78). ORR was superior in the pembrolizumab plus chemotherapy group (RR 1.24), while pembrolizumab monotherapy showed no significant difference from chemotherapy alone. Safety analysis revealed a higher frequency of adverse events in the pembrolizumab-based therapy groups compared to chemotherapy. Pembrolizumab together with chemotherapy improves greater survival and higher levels of response rate in patients with severe gastric cancer, especially with high PD-L1 expression. But it has rather more adverse events, allowing patient monitoring with care.

A Rare Case of Chronic Myeloid Leukemia with t(3;9;22) 3-way Translocation

Introduction/Objective

Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm originating from malignant clonal proliferation of a pluripotent hematopoietic stem cell. CML is characterized by a reciprocal translocation between chromosomes 9 and 22, t(9;22)(q34;q11), that gives rise to an abnormal chromosome 22 called the Philadelphia (Ph) chromosome. The translocation results in the formation of a chimeric BCR-ABL1 fusion gene, which is the molecular hallmark of the disease. However, 5-10% of CML patients present with additional chromosomal abnormalities which is often considered a sign of clonal evolution, genetic instability, and is generally thought to portend a poor prognosis.

Methods

We present a case of CML with a rare 3- way translocation, t(3;9;22)(q21;q34;q11.2), who achieved a major molecular response on imatinib for 18 months. A review of the literature and Mitelman database search is presented focusing on the prognostic implications of this 3 way translocation in the era of tyrosine kinase inhibitors starting in 2001 till now.

Results

Twenty seven cases were reported, but the patient therapeutic response to imatinib and clinical outcome were only reported in 11 cases. Nine cases achieved a cytogenetic remission while the remaining two cases had an adverse outcome.

Conclusion

Taken in conjunction with the favorable outcome in our patient, we suggest that t(3;9;22) is not an adverse prognostic factor in the era of tyrosine kinase inhibitors.