Reply to the 'Comment on "Strong Be-Be bonds in double-aromatic bridged Be2(µ-SO) molecules"' by A. Guha, Dalton Transactions, 2023, 52, D3DT00774J.

Recently, Ankur Kanti Guha suggested in his comment that (1) some calculation reveals that there is no Be-Be interaction in our proposed cluster, (2) the calculated Wiberg bond index of the Be-Be is very small (0.01), indicating that there is no interaction between the Be atoms, and (3) the proposed bridged structure is energetically very high in the potential energy surface. We have attempted to answer these points.

Strong Be-Be bonds in double-aromatic bridged Be2(µ-SO) molecules.

A bridged Be2(µ-SO) molecule is formed by stabilizing the Be2 dimer using a SO ligand. In this molecule, which is thermodynamically stable, the Be2 moiety behaves as an efficient electron donor toward the SO fragment. The ionic character of Be2δ+ and SOδ- in this molecule is confirmed by NBO analysis. Energy decomposition analysis shows that the strongest attractive interactions in this molecule are the polarization and exchange interactions. Also, Adaptive Natural Density Partitioning (AdNDP) analysis indicates the stability of this molecule, which could be due to the double-aromatic character of this system. Therefore, it seems that the title molecule could be experimentally detected.

Cytosolic expression of functional Fab fragments in Escherichia coli using a novel combination of dual SUMO expression cassette and EnBase® cultivation mode.

AIMS: The Escherichia coli expression system is highly effective in producing recombinant proteins. However, there are some limitations in this system, especially in obtaining correctly folded forms of some complex proteins such as Fab fragments. To improve the solubility and folding quality of Fab fragments, we have examined the effect of simultaneous application of a SUMO fusion tag, EnBase® cultivation mode and a redox mutant strain in the E. coli expression system. METHODS AND RESULTS: A bicistronic gene construct was designed to express an antivascular endothelial growth factor (VEGF) Fab fragment as a model system. The construct contained a dual SUMO fusion gene fragment to encode SUMO-tagged heavy and light chains. While the expression of the construct in batch cultures of BL21 or SHuffle® transformants produced insoluble and unfolded products, the induction of the transformants in EnBase® medium resulted in soluble and correctly folded Fab fragment, reaching as high as 19% of the total protein in shuffle strain. The functional assays indicated that the biological activity of the target Fab is similar to the commercial anti-VEGF, Lucentis® . CONCLUSIONS: This study demonstrated that the combination of SUMO fusion technology, EnBase® cultivation system and recruiting a redox mutant of E. coli can efficiently enhance the solubility and productivity of recombinant Fab fragments. SIGNIFICANCE AND THE IMPACT OF THE STUDY: The presented strategy provides not only a novel method to produce soluble and active form of an anti-VEGF Fab but also may use in the efficient production of other antibody fragments.

Antibiotic susceptibility pattern and identification of quinolone-resistant strains of Klebsiella pneumoniae clinical specimens from Khorramabad, Iran.

The present investigation is designed to evaluate antibiotic susceptibility pattern and identification of qnr strains of Klebsiella pneumoniae in clinical specimens isolated from general hospitals in Khorramabad, Iran. Total of 107 K. pneumoniae isolates were randomly collected since December 2011 until September 2012 from hospitalized patients at general hospitals in Khorramabad, Iran. The isolates were collected from different clinical samples including urine, sputum, lesion, and blood. Biochemical tests were performed for identification of isolates. Antibiotic susceptibility test was performed using disc diffusion method according to recommendations of Clinical and Laboratory Standards Institute using 13 antibiotic disks. K. pneumoniae isolates were screened by multiplex PCR amplification of qnrA, qnrB and qnrS using specific primers and sequence analysis of amplified regions of the isolates was also performed. Chi-square test was used to analysis and P value of < 0.05 was considered statistically significant. All clinical isolates were confirmed as K. pneumoniae by complete biochemical identification (gram staining, oxidase negative, indole positive, Simon's citrate positive and urease positive). Forty-three (40.2%) out of 107 isolates were multidrug-resistant (MDR). Ciprofloxacin (quinolone) susceptibility testing showed that 34 isolates (31.8%) were resistant, 7 isolates (6.5%) were intermediately resistant and 66 isolates (61.7%) were sensitive. Eighteen (16.8%) out of 107 K. pneumoniae clinical isolates were positive for qnr genes. Among all the qnr-positive isolates, 16 isolates (88.9%) carried qnrB, 1 isolate (5.55%) carried qnrS and the rest (5.55%) carried both qnrB and qnrS genes while no qnrA was detected in these clinical isolates. Qnr determinants were detected in 8 (23.5%) of the ciprofloxacinresistant isolates as well as 1 (14.3%) and 9 (13.6%) intermediate and sensitive isolates, respectively. No significant association was observed between ciprofloxacin resistance and presence of qnr genes (P>0.05). Findings of the present study indicated high frequency of qnr-positive K. pneumoniae in Lorestan province, Iran. However, there is no association between quinolone resistance and presence of qnr genes in isolates of K. pneumoniae.

Fentanyl transdermal patch (Durogesic® D-TRANS) for post abdominal laparotomy analgesia: a double blind randomized study.

AIM: The fentanyl transdermal patch (Duro-gesic® D-TRANS) is a strong pain medication for moderate to severe chronic pain that can provide long-lasting relief for persistent pain. This study was conducted to determine the analgesia and adverse effects of the fentanyl transdermal patch (Durogesic® D-TRANS) postelective laparotomy. METHODS: One-hundred twenty patients undergoing elective laparotomy were randomized into two groups of fentanyl and placebo. In the first group, patients received two fentanyl patches with 25 and 50 µg in 10 hours preoperatively. Patient's postoperative assessments included pain score, adverse effects, mean amount and interval of supplementary morphine, respiratory rate and oxygen saturation, which were recorded during 36 hours. RESULTS: The mean pain intensity scores over 36 hours in fentanyl transdermal patch durogesic (FTD) group were significantly less than placebo group (FTD, 35.28; placebo, 46.61 and P=0.01). However, the pain score at the 3rd timepoint in the placebo group was slightly less than the FTD group (39.4±2.23 vs. 39.47±4.97, respectively). The mean interval and amount of supplementary morphine were significantly better in the FTD group than the placebo group (FTD 367.7±349.7 min vs. placebo 59±13.88 min; P=0.04 and FTD 2.10±3.46 mg vs. 29.15±3.71 mg; P<0.001, respectively). The incidence of adverse effects including vomiting (FTD 16 vs. placebo 9; P=0.45), nausea (FTD 22 vs. placebo 18; P=0.33), itching (FTD 16 vs. placebo 18; P=1.00) and respiratory depression (FTD 1 vs. placebo 0; P=1.00) were not significant between the groups, except the dizziness that had a higher incidence in the FTD group (FTD 23 vs. placebo 1; P=0.02). CONCLUSION: It seems that the fentanyl transdermal patch system is a safe and effective procedure to use in post laparotomy analgesia and its related adverse effects are not serious.

Periodontopathic bacteria and herpesviruses in chronic periodontitis.

Periodontal disease involves complex interactions of microorganisms and host defenses. This work investigated the associations between putative bacterial pathogens, herpesviruses and chronic periodontitis. Subgingival samples were collected from 40 periodontally healthy individuals and from 40 patients with chronic periodontitis with probing depths of < or =3 mm or > or =6 mm. Multiplex and nested polymerase chain reactions were used to identify bacterial pathogens and herpesviruses. Porphyromonas gingivalis, Tannerella forsythia, Epstein-Barr virus (EBV) type 1, cytomegalovirus (CMV), Aggregatibacter actinomycetemcomitans and EBV type 2 were detected in, respectively, 95, 75, 72.5, 50, 12.5 and 10% of sites with probing depths > or =6 mm. P. gingivalis, T. forsythia, EBV-1 and CMV were statistically associated with probing depths > or =6 mm. A. actinomycetemcomitans and EBV-2 showed no association with periodontitis sites, and no significant associations were found for any of the test infectious agents and probing depths < or =3 mm. Our results confirm an association between P. gingivalis, T. forsythia, EBV-1 and CMV, and chronic periodontitis. These infectious agents may play an important synergistic role in the pathogenesis of chronic periodontitis.