Persimmon tannin promotes the growth of Saccharomyces cerevisiae under ethanol stress.

BACKGROUND: Saccharomyces cerevisiae plays a pivotal role in various industrial processes, including bioethanol production and alcoholic beverage fermentation. However, during these fermentations, yeasts are subjected to various environmental stresses, such as ethanol stress, which hinder cell growth and ethanol production. Genetic manipulations and the addition of natural ingredients rich in antioxidants to the culture have been shown to overcome this. Here, we investigated the potential of persimmon tannins, known for their antioxidative properties, to enhance the ethanol stress tolerance of yeast. RESULTS: Assessment of the effects of 6.25 mg mL-1 persimmon tannins after 48 h incubation revealed cell viability to be increased by 8.9- and 6.5-fold compared to the control treatment with and without 12.5% ethanol, respectively. Furthermore, persimmon tannins reduced ethanol-induced oxidative stress, including the production of cellular reactive oxygen species and acceleration of lipid peroxidation. However, persimmon tannins could hardly overcome ethanol-induced cell membrane damage. CONCLUSION: The findings herein indicate the potential of persimmon tannin as a protective agent for increasing yeast tolerance to ethanol stress by restricting oxidative damage but not membrane damage. Overall, this study unveils the implications of persimmon tannins for industries relying on yeast. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Aqua-{µ-1,4-bis-[(1,4,7,10-tetra-aza-cyclo-dodecan-1-yl)meth-yl]benzene}(nitrato-κO)dicopper(II) tris-(nitrate) trihydrate.

In the title dinuclear CuII complex, [Cu2(NO3)(C24H46N8)(H2O)](NO3)3·3H2O, the two CuII mol-ecules both have a square-pyramidal geometry, but the ligands in the axial positions are different: a water mol-ecule and a nitrate ion. All nitrate ions, water mol-ecules, and N-H groups are involved in an inter-molecular hydrogen-bond network.

Structural Characterization of Zinc(II)/Cobalt(II) Complexes of Chiral N-(Anthracen-9-yl)methyl-N,N-bis(2-picolyl)amine and Evaluation of DNA Photocleavage Activity.

We designed and synthesized a chiral ligand N-(anthracen-9-ylmethyl)-1-(pyridin-2-yl)-N-(pyridin-2-ylmethyl)ethanamine (APPE) DNA photocleavage agent to investigate the effects of chirality of bis(2-picolyl)amine on the DNA photocleavage activity of metal complexes. The structures of ZnII and CoII complexes in APPE were analyzed via X-ray crystallography and fluorometric titration. APPE formed metal complexes with a 1 : 1 stoichiometry in both the crystalline and solution states. Fluorometric titration was used to show that the ZnII and CoII association constants of these complexes (log Kas) were 4.95 and 5.39, respectively. The synthesized complexes were found to cleave pUC19 plasmid DNA when irradiated at 370 nm. The DNA photocleavage activity of the ZnII complex was higher than that of the CoII complex. The absolute configuration of the methyl-attached carbon did not affect DNA cleavage activity and, unfortunately, an achiral APPE derivative without the methyl group (ABPM) was found to perform DNA photocleavage more effectively than APPE. One reason for this may be that the methyl group suppressed the structural flexibility of the photosensitizer. These results will be useful for the design of new photoreactive reagents.

Dehydrozingerone enhances the fungicidal activity of glabridin against Saccharomyces cerevisiae and Candida albicans.

Drug resistance commonly occurs when treating immunocompromized patients with fungal infections. Dehydrozingerone-a phenolic compound isolated from the rhizome of Zingiber officinale-inhibits drug efflux in Saccharomyces cerevisiae by overexpression of the ATP-binding cassette (ABC) transporter Pdr5p. We aimed to investigate whether dehydrozingerone enhances the antifungal activity of glabridin-an isoflavan isolated from the roots of Glycyrrhiza glabra L.-by attenuating multidrug resistance through the intrinsic expression system of multidrug-efflux-related genes in a wild-type strain of the model yeast. The antifungal activity of 50 µmol l-1 glabridin alone was weak and temporary against S. cerevisiae; however, cell viability was significantly inhibited when the cells were co-treated with glabridin and dehydrozingerone. This enhancement was also observed in human pathogenic Candida albicans. Glabridin efflux did not depend on a particular drug efflux pump; instead, the transcription factors PDR1 and PDR3-regulating the transcription of multiple genes encoding drug efflux pumps-were involved in the antifungal activity and efflux of glabridin. qRT-PCR analysis revealed that dehydrozingerone reduced glabridin-induced overexpression of the ABC transporter-related genes PDR1, PDR3, and PDR5 to the levels observed in untreated cells. Our findings indicated that dehydrozingerone potentiates the efficacy of plant-derived antifungals through its effects on ABC transporters.

Short-term efficacy of exercise therapy for temporomandibular disorders: a case control study.

[Purpose] This study compared the short-term outcomes of manual therapy performed by a dentist and home exercises performed by patients as a single exercise therapy program for temporomandibular joint anterior disc displacement without reduction. [Participants and Methods] In this study we included seventeen patients with temporomandibular joint anterior disc displacement without reduction, moderate or greater temporomandibular joint functional impairment, and no treatment interventions. Patients receiving treatment underwent exercise therapy at the time of their first visit, whereas those in the non-treatment group received only an explanation of the condition. We evaluated the clinical symptoms (maximum painless opening distance, pain on motion and mastication, and degree of difficulty in daily life) at the first visit and at the two-week follow-up visit. [Results] For both groups, maximum painless opening distance and degree of difficulty in daily life improved significantly. For the treatment group, the pain on motion and mastication values significantly improved throughout the assessment period. [Conclusion] An exercise therapy program may be useful for the early treatment of temporomandibular joint anterior disc displacement without disc reduction.

Upregulation of Piezo2 in the mesangial, renin, and perivascular mesenchymal cells of the kidney of Dahl salt-sensitive hypertensive rats and its reversal by esaxerenone.

The recent discovery of mechanosensitive ion channels has promoted mechanobiological research in the field of hypertension and nephrology. We previously reported Piezo2 expression in mouse mesangial and juxtaglomerular renin-producing cells, and its modulation by dehydration. This study aimed to investigate how Piezo2 expression is altered in hypertensive nephropathy. The effects of the nonsteroidal mineralocorticoid receptor blocker, esaxerenone, were also analyzed. Four-week-old Dahl salt-sensitive rats were randomly assigned to three groups: rats fed a 0.3% NaCl diet (DSN), rats fed a high 8% NaCl diet (DSH), and rats fed a high salt diet supplemented with esaxerenone (DSH + E). After six weeks, DSH rats developed hypertension, albuminuria, glomerular and vascular injuries, and perivascular fibrosis. Esaxerenone effectively decreased blood pressure and ameliorated renal damage. In DSN rats, Piezo2 was expressed in Pdgfrb-positive mesangial and Ren1-positive cells. Piezo2 expression in these cells was enhanced in DSH rats. Moreover, Piezo2-positive cells accumulated in the adventitial layer of intrarenal small arteries and arterioles in DSH rats. These cells were positive for Pdgfrb, Col1a1, and Col3a1, but negative for Acta2 (αSMA), indicating that they were perivascular mesenchymal cells different from myofibroblasts. Piezo2 upregulation was reversed by esaxerenone treatment. Furthermore, Piezo2 inhibition by siRNA in the cultured mesangial cells resulted in upregulation of Tgfb1 expression. Cyclic stretch also upregulated Tgfb1 in both transfections of control siRNA and Piezo2 siRNA. Our findings suggest that Piezo2 may have a contributory role in modulating the pathogenesis of hypertensive nephrosclerosis and have also highlighted the therapeutic effects of esaxerenone on salt-induced hypertensive nephropathy. Mechanochannel Piezo2 is known to be expressed in the mouse mesangial cells and juxtaglomerular renin-producing cells, and this was confirmed in normotensive Dahl-S rats. In salt-induced hypertensive Dahl-S rats, Piezo2 upregulation was observed in the mesangial cells, renin cells, and notably, perivascular mesenchymal cells, suggesting its involvement in kidney fibrosis.

A novel gyrase inhibitor from toxin-antitoxin system expressed by Staphylococcus aureus.

Toxin-antitoxin (TA) systems consist of a toxin inhibiting essential cellular functions (such as DNA, RNA and protein synthesis), and its cognate antitoxin neutralizing the toxicity. Recently, we identified a TA system termed TsbA/TsbT in the Staphylococcus aureus genome. The induction of the tsbT gene in Escherichia coli halted both DNA and RNA synthesis, reduced supercoiled plasmid and resulted in increasingly relaxed DNA. These results suggested that DNA gyrase was the target of TsbT. In addition, TsbT inhibited both E. coli and S. aureus DNA gyrase activity and induced linearization of plasmid DNA in vitro. Taken together, these results demonstrate that the TsbT toxin targets DNA gyrase in vivo. Site-directed mutagenesis experiments showed that the E27 and D37 residues in TsbT are critical for toxicity. Secondary structure prediction combining the analysis of vacuum-ultraviolet circular-dichroism spectroscopy and neural network method demonstrated that the 22nd-32nd residues of TsbT form an α-helix structure, and that the E27 residue is located around the centre of the α-helix segment. These findings give new insights not only into S. aureus TA systems, but also into bacterial toxins targeting DNA topoisomerases.

Construction of an experimental study and addition of adapter sequences using HiDi DNA polymerase for improving DNA normalization methods relevant to novel gene discovery.

Microorganisms in the environment can be distinguished into dominant and rare microbial species based on their genes. It is difficult to obtain genetic information derived from rare microbial species (rare genes) because of the differences in relative abundance. DNA normalization is an approach that is used to obtain genetic information derived from rare microbial species from an environmental sample. This method involves the addition of adapter sequences for the amplification, denaturation, and reassociation of the DNA fragments and single-stranded DNA (ssDNA)/double-stranded DNA (dsDNA) separation. In this method, the amount of a high-copy-number of DNA fragments and a low-copy-number of DNA fragments can be equalized. Improvements in this technique are expected to provide novel genetic information or genes in rare microbial species. However, few model experimental systems have been reported to validate the DNA normalization techniques. This study is aimed to improve the DNA normalization technique used to obtain genetic information of rare genes from rare microbial species. An experimental study was constructed with two antibiotic resistance genes, whose copy numbers differed up to a million-fold. Both genes were mixed and the mixture of DNA fragments, of high- and low-copy-number, containing these genes was normalized by separating ssDNA/dsDNA fragments using hydroxyapatite. Normalized DNA fragments were introduced into Escherichia coli and DNA normalization was evaluated by counting colonies. Moreover, we improved the method to amplify a low-copy-number of DNA fragments by the addition of adapter sequences to DNA fragments using HiDi DNA polymerase to increase the efficiency of DNA normalization. This normalization method was achieved with a 100,000-fold difference. These methods allowed for quantitative evaluation of the DNA normalization efficiency. The experimental data and methods obtained in this study are expected to improve the DNA normalization efficiency to obtain novel genetic information or genes.

Difference in the Inhibitory Effect of Thiol Compounds and Demetallation Rates from the Zn(II) Active Site of Metallo-ß-lactamases (IMP-1 and IMP-6) Associated with a Single Amino Acid Substitution.

Gram-negative bacteria producing metallo-ß-lactamases (MBLs) have become a considerable threat to public health. MBLs including the IMP, VIM, and NDM types are Zn(II) enzymes that hydrolyze the ß-lactam ring present in a broad range of antibiotics, such as N-benzylpenicillin, meropenem, and imipenem. Among IMPs, IMP-1 and IMP-6 differ in a single amino acid substitution at position 262, where serine in IMP-1 is replaced by glycine in IMP-6, conferring a change in substrate specificity. To investigate how this mutation influences enzyme function, we examined lactamase inhibition by thiol compounds. Ethyl 3-mercaptopropionate acted as a competitive inhibitor of IMP-1, but a noncompetitive inhibitor of IMP-6. A comparison of the crystal structures previously reported for IMP-1 (PDB code: 5EV6) and IMP-6 (PDB code: 6LVJ) revealed a hydrogen bond between the side chain of Ser262 and Cys221 in IMP-1 but the absence of hydrogen bond in IMP-6, which affects the Zn2 coordination sphere in its active site. We investigated the demetallation rates of IMP-1 and IMP-6 in the presence of chelating agent ethylenediaminetetraacetic acid (EDTA) and found that the demetallation reactions had fast and slow phases with a first-order rate constant (kfast = 1.76 h-1, kslow = 0.108 h-1 for IMP-1, and kfast = 14.0 h-1 and kslow = 1.66 h-1 for IMP-6). The difference in the flexibility of the Zn2 coordination sphere between IMP-1 and IMP-6 may influence the demetallation rate, the catalytic efficiency against ß-lactam antibiotics, and the inhibitory effect of thiol compounds.

Functional characterization and transcriptional repression by Lacticaseibacillus paracasei DinJ-YafQ.

DinJ-YafQ is a bacterial type II TA system formed by the toxin RNase YafQ and the antitoxin protein DinJ. The activity of YafQ and DinJ has been rigorously studied in Escherichia coli, but little has been reported about orthologous systems identified in different microorganisms. In this work, we report an in vitro and in vivo functional characterization of YafQ and DinJ identified in two different strains of Lacticaseibacillus paracasei and isolated as recombinant proteins. While DinJ is identical in both strains, the two YafQ orthologs differ only for the D72G substitution in the catalytic site. Both YafQ orthologs digest ribosomal RNA, albeit with different catalytic efficiencies, and their RNase activity is neutralized by DinJ. We further show that DinJ alone or in complex with YafQ can bind cooperatively to a 28-nt inverted repeat overlapping the -35 element of the TA operon promoter. Atomic force microscopy imaging of DinJ-YafQ in complex with DNA harboring the cognate site reveals the formation of different oligomeric states that prevent the binding of RNA polymerase to the promoter. A single amino acid substitution (R13A) within the RHH DNA-binding motif of DinJ is sufficient to abolish DinJ and DinJ-YafQ DNA binding in vitro. In vivo experiments confirm the negative regulation of the TA promoter by DinJ and DinJ-YafQ and unveil an unexpected high expression-related toxicity of the gfp reporter gene. A model for the binding of two YafQ-(DinJ)2-YafQ tetramers to the promoter inverted repeat showing the absence of protein-protein steric clash is also presented. KEY POINTS: • The RNase activity of L. paracasei YafQ toxin is neutralized by DinJ antitoxin. • DinJ and DinJ-YafQ bind to an inverted repeat to repress their own promoter. • The R13A mutation of DinJ abolishes DNA binding of both DinJ and DinJ-YafQ.

Epidemiology of bloodstream infections and surface swab cultures in burn patients.

Aim: For infection control in burn patients, it is essential to understand the epidemiology of bloodstream infection (BSI) and the local microbiological situation. There are few studies on blood and swab culture results among burn patients in Japan. The purpose of this study was to investigate the epidemiology of BSI and swab cultures in burn patients. Methods: Data from 355 burn patients over 13 years from 2008 were analyzed retrospectively. Bloodstream infection was defined as the isolation of bacteria or fungi from two or more blood cultures. The characteristics of burn patients and microorganisms detected from various cultures were analyzed. Results: The mortality rate among burn patients with BSI was 37.8%, which was more than twice that among burn patients without BSI. The univariate analysis showed that inhalation injury, total burn surface area (TBSA), and mortality were associated with BSI. The multivariate logistic analysis indicated that TBSA was an independent risk factor for BSI. The most frequently isolated organism from blood and swab cultures were Candida species and Pseudomonas aeruginosa, respectively. Seventy-five percent of the microorganisms isolated from blood were detected previously in swab cultures performed within 1 week from blood cultures. Conclusions: The prognosis of burn patients with BSI was poor, and TBSA was an independent risk factor for BSI. The predominant organisms isolated from blood and swab cultures were Candida species and P. aeruginosa, respectively. Surveillance wound swab cultures could be utilized for monitoring the local microbiological situation in burn patients.

Delayed tension gastrothorax caused necrosis of stomach and re-expansion pulmonary edema: a case report.

BACKGROUND: Traumatic tension gastrothorax is a rare and potentially fatal condition occurring in patients with congenital or acquired diaphragmatic defects. Traumatic tension gastrothorax leads to acute and severe respiratory distress. Delayed tension gastrothorax that develops late during injury can be more severe. CASE PRESENTATION: An 84-year-old woman was brought to our facility with cardiac arrest and returned to spontaneous circulation after 2 min of cardiopulmonary resuscitation. Computed tomography showed diaphragmatic injury and tension gastrothorax due to trauma because of a fall episode few days earlier. Emergency thoracotomy and laparotomy was performed, because nasogastric tube insertion failed. There was a partially necrotic stomach in the chest cavity. The stomach was retracted from the thoracic cavity into the abdominal cavity and placed in its proper position. There was a 5 cm tear of the diaphragm. The tear was sutured and closed and then the necrotic area of the stomach was resected. Although the surgery relieved the intrathoracic compression, it resulted in re-expansion pulmonary edema immediately after surgery and hypoxemia. The patient was unable to overcome the hypoxemic state and eventually died. CONCLUSIONS: Delayed tension gastrothorax can lead not only to obstructive shock due to intrathoracic compression but also to more severe organ ischemia and re-expansion pulmonary edema due to insufflation.

Piezo2 expression and its alteration by mechanical forces in mouse mesangial cells and renin-producing cells.

The kidney plays a central role in body fluid homeostasis. Cells in the glomeruli and juxtaglomerular apparatus sense mechanical forces and modulate glomerular filtration and renin release. However, details of mechanosensory systems in these cells are unclear. Piezo2 is a recently identified mechanically activated ion channel found in various tissues, especially sensory neurons. Herein, we examined Piezo2 expression and regulation in mouse kidneys. RNAscope in situ hybridization revealed that Piezo2 expression was highly localized in mesangial cells and juxtaglomerular renin-producing cells. Immunofluorescence assays detected GFP signals in mesangial cells and juxtaglomerular renin-producing cells of Piezo2GFP reporter mice. Piezo2 transcripts were observed in the Foxd1-positive stromal progenitor cells of the metanephric mesenchyme in the developing mouse kidney, which are precursors of mesangial cells and renin-producing cells. In a mouse model of dehydration, Piezo2 expression was downregulated in mesangial cells and upregulated in juxtaglomerular renin-producing cells, along with the overproduction of renin and enlargement of the area of renin-producing cells. Furthermore, the expression of the renin coding gene Ren1 was reduced by Piezo2 knockdown in cultured juxtaglomerular As4.1 cells under static and stretched conditions. These data suggest pivotal roles for Piezo2 in the regulation of glomerular filtration and body fluid balance.

Radiation Emergency Medical Preparedness in Japan: A Survey of Nuclear Emergency Core Hospitals.

OBJECTIVE: Based on experiences following the Great East Japan Earthquake and nuclear power plant accident in 2011, Nuclear Emergency Core Hospitals (NECHs) were designated as centers for radiation disaster management in Japan. This study aimed to investigate their current status and identify areas for improvement. METHODS: This cross-sectional study was conducted in October 2018. Demographic data were collected by a questionnaire with free text responses about attitudes toward NECHs. Considerations regarding risk communications during a radiation disaster were analyzed using qualitative text mining analysis. RESULTS: A total of 36 hospitals participated in this study. Only 31% of NECHs anticipated a radiation disaster. The importance of business continuity plans and risk communications was shown. Text analysis identified 7 important categories for health care workers during a radiation disaster, including media response, communications to hospital staff, risk communications, radiation effects on children, planning for a radiation disaster in the region, rumors, and the role in the region. CONCLUSION: The radiation disaster medical system and NECHs in Japan were surveyed. The importance of risk communications, planning for a radiation disaster in each region, and the role in the region are identified as issues that need to be addressed.

Critical anterior mediastinal hematoma without internal mammary artery injury caused by cardiopulmonary resuscitation: A case report.

BACKGROUND: Massive anterior mediastinal hematoma due to chest compression during cardiopulmonary resuscitation is often caused by internal mammary artery injury. However, critical massive anterior mediastinal hematoma without damage to major blood vessels is extremely rare. We report a case of life-threatening anterior mediastinal hematoma without internal mammary artery injury during extracorporeal cardiopulmonary resuscitation. CASE PRESENTATION: A 70-year-old man was transferred to our emergency department because of ventricular fibrillation arrest. Manual chest compressions and venoarterial extracorporeal membrane oxygenation were applied in the angiography room. Acute myocardial infarction was diagnosed, and percutaneous coronary intervention with stent placement was performed. Despite the establishment of venoarterial extracorporeal membrane oxygenation flow, the hemodynamics were unstable. Computed tomography revealed a massive anterior mediastinal hematoma compressing the right heart system and causing obstructive shock. Although local incision and anterior mediastinal hematoma drainage were tried for resolving obstructive shock, the patient's anemia did not improve, and there was still continuous hemorrhaging from the drainage tube. A median thoracotomy was then performed. There was no injury of the main trunk of the internal mammary artery but only hemorrhaging from the sternal fracture site. The patient's hemodynamics and anemia improved after hemostasis and gauze packing. Re-thoracotomy for gauze removal and sternal closure was performed three days post-hospitalization. CONCLUSIONS: It is important to consider hemorrhaging and unstable hemodynamics in patients who receive extracorporeal cardiopulmonary resuscitation. Therefore, a thoracotomy may take precedence over intravascular treatment for restoring hemostasis when there is no information regarding the bleeding site, such as the presence of extravasation.

Association between adjunct clindamycin and in-hospital mortality in patients with necrotizing soft tissue infection due to group A Streptococcus: a nationwide cohort study.

Necrotizing soft tissue infection (NSTI) due to group A Streptococcus (GAS) is a severe life-threatening microbial infection. The administration of adjunct clindamycin has been recommended in the treatment of NSTIs due to GAS. However, robust evidence regarding the clinical benefits of adjunct clindamycin in NSTI patients remains controversial. We aimed to investigate the association between early administration of adjunct clindamycin and in-hospital mortality in patients with NSTI attributed to GAS. The present study was a nationwide retrospective cohort study, using the Japanese Diagnosis Procedure Combination inpatient database focusing on the period between 2010 and 2018. Data was extracted on patients diagnosed with NSTI due to GAS. We compared patients who were administered clindamycin on the day of admission (clindamycin group) with those who were not (control group). A propensity score overlap weighting method was adopted to adjust the unbalanced backgrounds. The primary endpoint was in-hospital mortality and survival at 90 days after admission. We identified 404 eligible patients during the study period. After adjustment, patients in the clindamycin group were not significantly associated with reduced in-hospital mortality (19.2% vs. 17.5%; odds ratio, 1.11; 95% confidence interval, 0.59-2.09; p = 0.74) or improved survival at 90 days after admission (hazard ratio, 0.92; 95% confidence interval, 0.51-1.68; p = 0.80). In this retrospective study, early adjunct clindamycin does not appear to improve survival. Therefore, the present study questions the benefits of clindamycin as an adjunct to broad spectrum antibiotics in patients with NSTI due to GAS.

Prevalence of COVID-19 Mimics in the Emergency Department.

Objective Due to the lack of specific clinical manifestations and symptoms, it is difficult to distinguish COVID-19 from mimics. A common pitfall is to rush to make a diagnosis when encountering a patient with COVID-19-like symptoms. The present study describes a series of COVID-19 mimics using an outpatient database collected from a designated COVID-19 healthcare facility in Tokyo, Japan. Methods We established an emergency room (ER) tailored specifically for patients with suspected or confirmed COVID-19 called the "COVID-ER." In this single-center retrospective cohort study, we enrolled patients who visited the COVID-ER from February 1 to September 5, 2020. The outcomes included the prevalence of COVID-19, admission, potentially fatal diseases and final diagnosis. Results We identified 2,555 eligible patients. The median age was 38 (interquartile range, 26-57) years old. During the study period, the prevalence of COVID-19 was 17.9% (457/2,555). Non-COVID-19 diagnoses accounted for 82.1% of all cases. The common cold had the highest prevalence and accounted for 33.0% of all final diagnoses, followed by gastroenteritis (9.4%), urinary tract infections (3.8%), tonsillitis (2.9%), heat stroke (2.6%) and bacterial pneumonia (2.1%). The prevalence of potentially fatal diseases was 14.2% (298/2,098) among non-COVID-19 patients. Conclusion Several potentially fatal diseases remain masked among the wave of COVID-19 mimics. It is imperative that a thorough differential diagnostic panel be considered prior to the rendering of a COVID-19 diagnosis.

Crystal Structures of Metallo-ß-Lactamase (IMP-1) and Its D120E Mutant in Complexes with Citrate and the Inhibitory Effect of the Benzyl Group in Citrate Monobenzyl Ester.

The emergence and rapid spread of carbapenem-resistant pathogens producing metallo-ß-lactamases such as IMP-1 and NDM-1 have been of great concern in the global clinical setting. The X-ray crystal structures of IMP-1 from Serratia marcescens and its single mutant, D120E, in complexes with citrate were determined at resolutions of 2.00 and 1.85 Å, respectively. Two crystal structures indicate that a single mutation at position 120 caused a structural change around Zn1, where the geometry changes from a tetrahedron in the native IMP-1 to a square pyramid in D120E. Based on these two complex structures, the authors synthesized citrate monobenzyl ester 1 to evaluate the structural requirement for the inhibitory activity against IMP-1 and compared the inhibitory activities with nonsubstituted citrate. The introduction of a benzyl group into citrate enhanced the inhibitory activity in comparison to citrate (IC50 > 5 mM).

Development of potent antipseudomonal ß-lactams by means of polycarboxylation of aminopenicillins.

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that presents a serious risk to immunosuppressed individuals and other extremely vulnerable patients such as those in intensive care units. The emergence of multidrug-resistant Pseudomonas strains has increased the need for new antipseudomonal agents. In this study, a series of amino group-modified aminopenicillin derivatives was synthesized that have different numbers of carboxyl groups and structurally resemble carboxypenicillin-ureidopenicillin hybrids, and their antipseudomonal activities were evaluated. Among the derivatives synthesized, diethylenetriaminepentaacetic acid (DTPA)-modified amoxicillin (DTPA-Amox) showed potent antipseudomonal activity, not only against the laboratory strain PAO1 but also against clinically isolated Pseudomonas strains that were resistant to piperacillin and carbenicillin. DTPA-Amox had no obvious cytotoxic effects on cultured mammalian cells. In addition, in an in vivo model of leukopenia, DTPA-Amox treatment produced a moderate but statistically significant improvement in the survival of mice with P. aeruginosa strain PAO1 infection. These data suggest that polycarboxylation by DTPA conjugation is an effective approach to enhance antipseudomonal activity of aminopenicillins.