Synthetic phage-based approach for sensitive and specific detection of Escherichia coli O157

Escherichia coli O157 can cause foodborne outbreaks, with infection leading to severe disease such as hemolytic-uremic syndrome. Although phage-based detection methods for E. coli O157 are being explored, research on their specificity with clinical isolates is lacking. Here, we describe an in vitro assembly-based synthesis of vB_Eco4M-7, an O157 antigen-specific phage with a 68-kb genome, and its use as a proof of concept for E. coli O157 detection. Linking the detection tag to the C-terminus of the tail fiber protein, gp27 produces the greatest detection sensitivity of the 20 insertions sites tested. The constructed phage detects all 53 diverse clinical isolates of E. coli O157, clearly distinguishing them from 35 clinical isolates of non-O157 Shiga toxin-producing E. coli. Our efficient phage synthesis methods can be applied to other pathogenic bacteria for a variety of applications, including phage-based detection and phage therapy.

Harnessing a T1 Phage-Derived Spanin for Developing Phage-Based Antimicrobial Development

The global increase in the prevalence of drug-resistant bacteria has necessitated the development of alternative treatments that do not rely on conventional antimicrobial agents. Using bacteriophage-derived lytic enzymes in antibacterial therapy shows promise; however, a thorough comparison and evaluation of their bactericidal efficacy are lacking. This study aimed to compare and investigate the bactericidal activity and spectrum of such lytic enzymes, with the goal of harnessing them for antibacterial therapy. First, we examined the bactericidal activity of spanins, endolysins, and holins derived from 2 Escherichia coli model phages, T1 and T7. Among these, T1-spanin exhibited the highest bactericidal activity against E. coli. Subsequently, we expressed T1-spanin within bacterial cells and assessed its bactericidal activity. T1-spanin showed potent bactericidal activity against all clinical isolates tested, including bacterial strains of 111 E. coli, 2 Acinetobacter spp., 3 Klebsiella spp., and 3 Pseudomonas aeruginosa. In contrast, T1 phage-derived endolysin showed bactericidal activity against E. coli and P. aeruginosa, yet its efficacy against other bacteria was inferior to that of T1-spanin. Finally, we developed a phage-based technology to introduce the T1-spanin gene into target bacteria. The synthesized non-proliferative phage exhibited strong antibacterial activity against the targeted bacteria. The potent bactericidal activity exhibited by spanins, combined with the novel phage synthetic technology, holds promise for the development of innovative antimicrobial agents.

Potential Anti-Mpox Virus Activity of Atovaquone, Mefloquine, and Molnupiravir, and Their Potential Use as Treatments

BACKGROUND

Mpox virus (MPXV) is a zoonotic orthopoxvirus and caused an outbreak in 2022. Although tecovirimat and brincidofovir are approved as anti-smallpox drugs, their effects in mpox patients have not been well documented. In this study, by a drug repurposing approach, we identified potential drug candidates for treating mpox and predicted their clinical impacts by mathematical modeling.

METHODS

We screened 132 approved drugs using an MPXV infection cell system. We quantified antiviral activities of potential drug candidates by measuring intracellular viral DNA and analyzed the modes of action by time-of-addition assay and electron microscopic analysis. We further predicted the efficacy of drugs under clinical concentrations by mathematical simulation and examined combination treatment.

RESULTS

Atovaquone, mefloquine, and molnupiravir exhibited anti-MPXV activity, with 50% inhibitory concentrations of 0.51-5.2 μM, which was more potent than cidofovir. Whereas mefloquine was suggested to inhibit viral entry, atovaquone and molnupiravir targeted postentry processes. Atovaquone was suggested to exert its activity through inhibiting dihydroorotate dehydrogenase. Combining atovaquone with tecovirimat enhanced the anti-MPXV effect of tecovirimat. Quantitative mathematical simulations predicted that atovaquone can promote viral clearance in patients by 7 days at clinically relevant drug concentrations.

CONCLUSIONS

These data suggest that atovaquone would be a potential candidate for treating mpox.

Identification of IMP Dehydrogenase as a Potential Target for Anti-Mpox Virus Agents

Mpox virus (formerly monkeypox virus [MPXV]) is a neglected zoonotic pathogen that caused a worldwide outbreak in May 2022. Given the lack of an established therapy, the development of an anti-MPXV strategy is of vital importance. To identify drug targets for the development of anti-MPXV agents, we screened a chemical library using an MPXV infection cell assay and found that gemcitabine, trifluridine, and mycophenolic acid (MPA) inhibited MPXV propagation. These compounds showed broad-spectrum anti-orthopoxvirus activities and presented lower 90% inhibitory concentrations (0.026 to 0.89 μM) than brincidofovir, an approved anti-smallpox agent. These three compounds have been suggested to target the postentry step to reduce the intracellular production of virions. Knockdown of IMP dehydrogenase (IMPDH), the rate-limiting enzyme of guanosine biosynthesis and a target of MPA, dramatically reduced MPXV DNA production. Moreover, supplementation with guanosine recovered the anti-MPXV effect of MPA, suggesting that IMPDH and its guanosine biosynthetic pathway regulate MPXV replication. By targeting IMPDH, we identified a series of compounds with stronger anti-MPXV activity than MPA. This evidence shows that IMPDH is a potential target for the development of anti-MPXV agents. IMPORTANCE Mpox is a zoonotic disease caused by infection with the mpox virus, and a worldwide outbreak occurred in May 2022. The smallpox vaccine has recently been approved for clinical use against mpox in the United States. Although brincidofovir and tecovirimat are drugs approved for the treatment of smallpox by the U.S. Food and Drug Administration, their efficacy against mpox has not been established. Moreover, these drugs may present negative side effects. Therefore, new anti-mpox virus agents are needed. This study revealed that gemcitabine, trifluridine, and mycophenolic acid inhibited mpox virus propagation and exhibited broad-spectrum anti-orthopoxvirus activities. We also suggested IMP dehydrogenase as a potential target for the development of anti-mpox virus agents. By targeting this molecule, we identified a series of compounds with stronger anti-mpox virus activity than mycophenolic acid.

Peak oxygen uptake in cardiopulmonary exercise testing was associated with left ventricular diastolic dysfunction in patients with preserved ejection fraction

Background

Heart failure with preserved ejection fraction (EF) remains a poor prognosis as same as heart failure with reduced EF. Peak oxygen uptake (VO2) by cardiopulmonary exercise testing (CPET) is a useful parameter for predicting cardiovascular diseases prognosis. Furthermore, though there are some reports that CPET parameters are associated with indicators of diastolic dysfunction, each of these indicators has some limitations. Recently, recommendations for the evaluation of left ventricular diastolic function by echocardiography were reported from the ASE/EACVI. However, no reports have examined the association between exercise tolerance indices and diastolic dysfunction based on these recommended variables.

Purpose

To examine the relationship between peak VO2 and diastolic dysfunction using the recommendation from ASE/EACVI in cardiovascular diseases patients with preserved EF

Methods

We recruited 214 patients who were performed both CPX and echocardiography. EF ≥50% was 99 patients. All patients underwent 0W warm-up and 10W ramp on an upright electrical bicycle ergometer. Diastolic dysfunction was assessed using the recommendations for the evaluation of diastolic function by ASE/EACVI. We used abnormal cutoff values are annular e' velocity: septal e' <7 cm/s, lateral e' <10 cm/s, average E/e' ratio >14, left atrial volume index >34 ml/m2, and peak tricuspid regurgitation (TR) velocity >2.8 m/s. Diastolic dysfunction is present if more than half of the available parameters meet these cutoff values.

Results

Mean age was 57±14 years old, the portion of women was 69%. The portion of diastolic dysfunction was 16%. In univariable logistic regression analysis, age, log BNP, septal e' <7 cm/s or lateral e' <10 cm/s, peak TR velocity >2.8 m/s, and the presence of diastolic dysfunction were significantly associated with peakVO2 <14 ml/min/kg. In multivariable logistic regression analysis, the presence of diastolic dysfunction was an independent risk factor for peak VO2 <14 ml/min/kg (OR 5.03 CI 1.32–19.2, p=0.018). Furthermore, we investigated the association between each variable of diastolic dysfunction and peak VO2 and found that low septal and lateral e'velocity and high TR peak flow velocity were significantly associated with peak VO2 <14 ml/min/kg.

Conclusions

In preserved EF, low peak VO2 was significantly associated with diastolic dysfunction assessed by the recommendations from the ASE/EACVI.

Funding Acknowledgement

Type of funding sources: None.

Oxidative stress was significantly associated with peak oxygen uptake in patients with dilated cardiomyopathy

Background

Systemic oxidative stress is known to be associated with the severity and prognosis in patients with cardiovascular diseases (CVD), including chronic heart failure. On the other hand, exercise tolerance is closely related to the prognosis in heart failure patients. However, no report has examined how oxidative stress is involved in each parameter evaluated by cardiopulmonary exercise testing (CPET) in patients with dilated cardiomyopathy (DCM).

Purpose

To examine the relationship between oxidative stress and CPET parameters such as peak VO2 and VE/VCO2 slope in patients with DCM

Methods

We recruited 214 patients with CVD who were performed CPET and measured brain natriuretic peptide (BNP) and haemoglobin (Hb). Finally, we enrolled 96 patients with DCM who have dilated dimensions of the left ventricular lumen by echocardiography and are diagnosed by endomyocardial biopsy. All patients underwent CPET using 0W warm-up and 10W ramp protocol on an upright electrical bicycle ergometer. We defined low peak VO2 as peak VO2<14 ml/min/kg and high VE/VCO2 slope as VE/VCO2 slope>34. The oxidative stress level was evaluated by a d-ROMs test, in which the amount of organic hydroperoxide converted into radicals oxidizing N, N-diethyl-p-phenylenediamine hydroperoxide is measured. The high level of d-ROMs was defined as d-ROMs≥401 U.CARR.

Results

Mean age was 56±15 years old. Mean ejection fraction, peak VO2 and VE/VCO2 slope were 37±15%, 16.3±5.0 ml/min/kg, and 31.0±11.8, respectively. The percentage of the high level of d-ROMs was 25%. In univariable logistic regression analysis, Hb, log BNP, and the high level of oxidative stress were significantly associated with low peak VO2, whereas, in multivariable logistic regression analysis, age, Hb, and log BNP were significant factors for high VE/VCO2 slope. In multivariable logistic regression analysis, only the high level of d-ROMs was independently associated with low peak VO2 (OR 3.18, CI 1.12–9.04, p=0.030). While, in multivariable logistic regression analysis, Hb (OR 0.51, CI 0.32–0.81, p=0.004) and log BNP (OR 2.77, CI 1.33–5.76, p=0.006) were significantly related to high VE/VCO2 slope.

Conclusions

In patients with DCM, low peak VO2 was associated with the high level of d-ROMs, and high VE/VCO2 slope was associated with BNP. These results suggested that oxidative stress was only related to peak VO2.

Funding Acknowledgement

Type of funding sources: None.

Development of a risk prediction score and equation for chronic kidney disease: a retrospective cohort study

Background

Chronic kidney disease (CKD) is a risk factor for end-stage renal disease and contributes to increased risk of cardiovascular disease morbidity and mortality. We aimed to develop a risk prediction score and equation for future onset of CKD using large-scale health checkup data.

Methods

This retrospective cohort study included 58,423 participants without baseline CKD who were randomly assigned to Derivation (n=38,948) and Validation cohorts (n=19,475) at a ratio of 2:1. The predictors were anthropometric indices, life style, and blood sampling data. In the Derivation cohort, we performed multivariable logistic regression analysis and obtained the standardized beta coefficient of each factor that was significantly associated with new-onset CKD and assigned scores to each factor. We created a score and an equation to determine the risk of developing CKD after 5 years and applied them to the Validation cohort to assess their reproducibility.

Results

The risk prediction scores ranged from 0 to 16, consisting of the seven indicators, including age, sex, hypertension, dyslipidemia, diabetes, hyperuricemia, and estimated glomerular filtration rate (eGFR). From the receiver operating characteristic (ROC) curve predicting CKD incidence, the area under the curve (AUC) was 0.78. A score of ≥8 showed the highest Youden index in the Derivation cohort, with a sensitivity of 0.90 and specificity of 0.52. The CKD incidence gradually and constantly increased as the score increased from ≤6 to ≥14 (Figure). The risk prediction equation consisted of aforementioned seven indicators: 1/(1 + exp[−(9.4876 + 0.0311×age + 0.2400×sex + 0.3470×hypertension + 0.0893×dyslipidemia + 0.3444×diabetes + 0.0832×hyperuricemia + (−0.1980)×eGFR]). The median probability obtained from the Derivation cohort was 0.018 (interquartile range 0.002–0.084), and the AUC value of the ROC curve for the development of CKD after 5 years was 0.88, with a sensitivity of 0.84 and a specificity of 0.78 at a cutoff value of 0.077. The Validation cohort analysis yielded similar results.

Conclusion

We developed a clinically useful risk score and equation to predict the CKD incidence after 5 years in the general Japanese population. These models have reasonably high predictability and reproducibility.

Funding Acknowledgement

Type of funding sources: None.

wecB Gene of Salmonella Gallinarum Plays a Critical Role in Systemic Infection of Fowl Typhoid

Salmonella enterica serovar Gallinarum (S. Gallinarum) is a host-specific pathogen causing fowl typhoid, a severe systemic infection in poultry, which leads to substantial economic losses due to high morbidity and mortality in many developing countries. However, less is known about the pathogenic characteristics and mechanism of S. Gallinarum-induced systemic infection in chickens. In this study, we deleted the S. Gallinarum UDP-N-acetylglucosamine-1-phosphate transferase gene, which contributes to the biosynthesis of enterobacterial common antigen (ECA), and studied the pathogenicity of this wecB::Cm strain in a chicken model of systemic infection. The wecB::Cm mutant strain showed comparable growth but lower resistance to bile acid and nalidixic acid than the wild-type strain in vitro. In the oral infection model of chickens, the virulence of the wecB::Cm strain was significantly attenuated in vivo. Chickens infected with wild-type strain showed typical clinical signs and pathological changes of fowl typhoid and died between 6 and 9 days post-infection, and the bacteria rapidly disseminated to systemic organs and increased in the livers and spleens. In contrast, the wecB::Cm mutant strain did not cause chicken death, there were no significant clinical changes, and the bacterial numbers in the liver and spleen of the chickens were significantly lower than those of the chickens infected with the wild-type strain. In addition, the expression of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and CXCLi1 in the livers of wecB::Cm-infected chickens was significantly lower than that of the chickens infected with the wild-type strain. Furthermore, the attenuated wecB::Cm strain could persistently colonize the liver and spleen at low levels for up to 25 days post-infection and could induce a protective immune response in the chickens. These results indicate that the wecB gene is an important virulence factor of S. Gallinarum in the chicken model of systemic infection, and the avirulent wecB::Cm mutant could possibly be used as a live-attenuated vaccine strain for controlling fowl typhoid.

Characteristics of systemic infection and host responses in chickens experimentally infected with Salmonella enterica serovar Gallinarum biovar Gallinarum

Salmonella enterica serovar Gallinarum biovar Gallinarum (S. Gallinarum) is a host-specific pathogen causing systemic infection in poultry, which leads to significant economic losses due to high mortality. However, little is known about the dynamic process of systemic infection and pathogenic characteristics of S. Gallinarum in chickens. In the present study, we developed an oral infection model that reproduces the pathology of S. Gallinarum and clarified the host immune response of the infected chickens. Chickens at 20 days of age orally inoculated at a dose of 10⁸ colony forming unit (CFU) showed typical clinical signs of fowl typhoid and died between 6 and 10 days post infection. The inoculated S. Gallinarum rapidly disseminated to multple organs and the bacterial counts increased in the liver and spleen at 3 days post infection. Pathological changes associated wirh inflammation in the liver and spleen became apparent at 4 days post infection, and increased expression of interferon (IFN)-γ and interleuikin (IL)-12 in the liver and spleen did not observed until 3 days post infection. These results indicate that S. Gallinarum rapidly spread to entire body through intestine, and the low-level of inflammatory responses in the liver during the early stage of infection may contribute to rapid, systemic dissemination of the bacteria. Our infection model and findings will contribute to the better understanding of the pathogenic mechanism of S. Gallinarum, and provide new insights into the prevention and control of fowl typhoid.

Gender differences in the effects of weight reduction on future blood pressure elevation in the overweight middle-aged population

Background

The effectiveness of weight loss (WL) to prevent blood pressure (BP) elevation is common knowledge; however, the effect of gender differences on this efficacy is not known. We aimed to investigate whether there were gender differences in the degree of BP increase and the prevalence of hypertension in the future when middle-aged obese participants achieved slight WL.

Methods

We analyzed the annual health checkup data for the general Japanese population collected from January 2001 through December 2015. Middle-aged participants (40–49 years old) with overweight (body mass index [BMI], 25.0–29.9 kg/m2) who had examination data for two follow-up time-points (after 3 and 10 years) were included. The participants with a BMI decrease ≥1.0 kg/m2 in 3 years (WL group) were propensity score (PS)-matched to those with a BMI decrease <1.0 kg/m2 or weight gain (non-WL group) based on the data of the first examination, including age, BMI, smoking and drinking status, eGFR, systolic BP and diastolic BP, and hypertension (defined as SBP ≥140 mmHg and/or DBP ≥90 mmHg). We compared the BMI, systolic BP, and hypertension prevalence after 10 years in both groups.

Results

There were 17,554 individuals, aged 40–49 years, with overweight. After excluding subjects who did not satisfy the inclusion criteria and PS matching, we identified 232 men and 160 women in both WL and non-WL groups. The BMI in the WL group after 3 years was significantly lower than that in the non-WL group (men, 25.2±1.4 kg/m2 vs. 27.1±1.6 kg/m2, P<0.001; women, 24.9±1.4 kg/m2 vs. 27.1±1.5 kg/m2, P<0.001), and the significance persisted even after 10 years among both men and women (men, 25.5±1.8 kg/m2 vs. 26.8±2.1 kg/m2, P<0.001; women, 25.3±2.0 kg/m2 vs. 26.8±2.2 kg/m2, P<0.001). Among women, the systolic BP and hypertension prevalence after 10 years were significantly lower in the WL group than in the non-WL group (systolic BP, 124.8±16.3 mmHg vs. 130.3±19.0 mmHg, P<0.01; hypertension prevalence, 35.0% vs. 48.1%, P<0.05). In contrast, there were no significant differences in the SBP and hypertension prevalence after 10 years among men between the groups (systolic BP, 129.0±17.7 mmHg vs. 129.0±17.5 mmHg, P=0.96; hypertension prevalence, 46.1% vs. 48.7%, P=0.57).

Conclusions

There were gender differences in the effectiveness of WL to prevent future BP elevation in overweight middle-aged participants. WL could prevent future BP elevation and the hypertension onset in women but not in men.

Funding Acknowledgement

Type of funding source: None

Fib4 index is a more relevant marker for pulse wave velocity but not for carotid intima-media thickness in a men population

Background

Carotid intima-media thickness (IMT) and pulse wave velocity (PWV) are useful markers for predicting cardiovascular disease not only in patients with cardiovascular disease but also in the general population. On the other hand, liver disease due to obesity has become a problem and has been reported to be associated with the progression of atherosclerosis. Recently, an indicator of liver stiffness, the Fibrosis-4 index (Fib4 index), has been used to detect the pre-stage liver diseases. However, there is no report to investigate the association between atherosclerotic parameters such as IMT and PWV, and Fib4 index. The Fib4 index is a simple index calculated from age and three blood sample data, and it will be useful for screening for an early stage of atherosclerosis if we can show the association between Fib4 index and these parameters.

Purpose

To investigate the association between atherosclerotic parameters such as IMT or PWV and Fib4 index

Methods

We recruited 3, 128 men participants who underwent health checkup. IMT was evaluated by carotid ultrasonography, and branchial-ankle PWV (baPWV) was measured by an automatic device. We analysed the association of IMT or baPWV with Fib4 index and atherosclerotic risk factors such as age, systolic blood pressure (SBP), low-density lipoprotein cholesterol (LDL-C) and fasting blood sugar (FBS). baPWV ≥1,600 cm/s was defined high baPWV and we performed the receiver operating characteristics (ROC) analysis to demonstrate the significance of Fib4 index for baPWV.

Results

Mean Fib4 index was 1.39±0.68. In the univariate linear regression analysis, all factors such as age, SBP, LDL-C, FBS, Fib4 index were significantly associated with IMT or baPWV. On the other hand, in the multivariate linear regression analysis, Fib4 index was an independent factor for baPWV but not for IMT (IMT, p=0.498; baPWV, p=0.023). Figure 1 showed the result of ROC analysis to predict the high baPWV by Fib4 index. The area under curve (AUC) was 0.73, with the highest discriminating sensitivity and specificity at 0.71 and 0.65, respectively at Fib4 index = 1.27.

Conclusions

Fib4 index was significantly related to baPWV and could be the useful screening marker for arterial stiffness in a general men population.

Figure 1. ROC curve analysis

Funding Acknowledgement

Type of funding source: None

P6232Exploring the bottom of J-shaped curve association between serum uric acid and cardiovascular risks: description using a large Japanese general population

Background

The J-shaped association between serum uric acid (SUA) and cardiovascular risks is known. However, the bottom of the J-shaped curve has not been elucidated because of the lack of epidemiological knowledge about hypouricemia.

Purpose

To explore the SUA levels related to the most preferable cardiovascular risks using data from a Japanese general population.

Methods

Data from 246,923 individuals (111,117 men and 135,806 women) who underwent routine health checkups between January 2001 and December 2015 were analyzed. The participants were divided into quartiles according to their SUA levels, and patients with hypouricemia (SUA level <2.0 mg/dL) were subdivided into two groups according to their distributions. We compared their characteristics, including their cardiovascular risks.

Results

The prevalence of hypouricemia was 0.46% overall, 0.21% for men, and 0.66% for women (P<0.001). The subjects with hypouricemia were divided into two groups according to SUA level: a lower hypouricemia group (0.4–1.1 mg/dL, which included a peak at 0.7–0.8 mg/dL) and a higher hypouricemia group (1.4–2.0 mg/dL). The two groups exhibited significanly different characteristics in several variables: body mass index and triglyceride in men, and age, body mass index, triglyceride, low-density lipoprotein cholesterol, and renal function in women. Furthermore, several cardiovascular risk factors showed the most preferable values in subjects with SUA 1.4–2.0 mg/dL (Figure).

Conclusions

There were two independent distributions in subjects with SUA ≤2.0 mg/dL. The individuals with SUA 1.4–2.0 mg/dL exhibited the most preferable values for several cardiovascular risk factors, suggesting an association with the bottom of the J-shaped curve between SUA and cardiovascular risks.

Differential Distribution of Salmonella Serovars and Campylobacter spp. Isolates in Free-Living Crows and Broiler Chickens in Aomori, Japan

Salmonella and Campylobacter cause foodborne enteritis mainly via the consumption of raw/undercooked contaminated poultry meat and products. Broiler flocks are primarily colonized with these bacteria; however, the underlying etiology remains unclear. The present study was conducted in order to obtain further information on the prevalence and genotypic distribution of Salmonella and Campylobacter in free-living crows and broiler flocks in a region for 2 years, thereby facilitating estimations of the potential risk of transmission of C. jejuni from crows to broiler flocks. Salmonella serovars Bredeney and Derby were isolated from 8 and 3 out of 123 captured crows, respectively, both of which are not common in broiler chickens. Campylobacter were isolated from all 89 crows tested and C. jejuni was prevalent (85 crows). Pulsed field gel electrophoresis showed broad diversity in the crow isolates of C. jejuni. However, 3 crow isolates and 2 broiler isolates showing similar banding patterns were assigned to different sequence types in multi-locus sequence typing. These results indicate that crows do not share Salmonella serovars with broilers, and harbor various genotypes of C. jejuni that differ from those of broiler flocks. Thus, our results indicate that crows are not a potential vector of these bacteria to broiler flocks in this region.

Stereochemistry of 1,2-dichloroethane adsorbed on Pt(111)

The rotational isomerism of 1,2-dichloroethane (DCE, CH2ClCH2Cl) adsorbed on Pt(111) was studied in the temperature range of 35-100 K using high-resolution electron energy loss spectroscopy and metastable atom electron spectroscopy. In the coverage below monolayer the physisorbed and chemisorbed species coexist at 35 K in the gauche and slightly distorted trans form, respectively. Owing to the direct Pt-Cl interactions, the nonbonding Cl 3p states of the chemisorbed DCE are split off, giving rise to degradation in symmetry from the pure trans form (C2h). The physisorbed gauche conformers are arranged with the C2 axis parallel (or heavily tilted) to the substrate and converted irreversibly to the pseudo-trans form by heating at 70 K. In the multilayer, the trans and gauche conformers exist at 35 K, where the former population is increased with increasing layer thickness. Upon annealing the bilayer at 80 K, the irreversible conversion takes place to yield a higher population of the gauche conformer in the topmost layer. The conformational stabilities and mutual changes of DCE adsorbed on a metal surface are discussed in terms of intramolecular rotational potential.

Evaluation of a high-velocity flame-spraying technique for hydroxyapatite

Titanium alloy sprayed with hydroxyapatite (HA) was developed by a high-velocity flame-spraying technique (HVFST). Biocompatible responses of bony tissues to high-velocity flame-sprayed HA (HVFS-HA) implanted into tibias of adult male rabbits was investigated 4 and 18 months after implantation by light and electron microscopy. Both light and electron microscope features in histological sections showed that inflammatory responses of tissues in situ were completely cleared and the interface between the bone and the implant was filled with newly formed bony substrate. This suggests that the HVFS-HA was sufficiently biocompatible to be adapted to the bone in situ.

Thoracic myelopathy secondary to ossification of the spinal ligament

The authors describe their experience with 26 cases of thoracic myelopathy secondary to hypertrophic ossification of the spinal ligament (posterior longitudinal ligament and/or ligamentum flavum). The clinical manifestations of this condition and results of its surgical treatment are described. The commonest symptoms were numbness or tingling in the legs and feet and gait disturbance. Most of the patients with involvement of the upper thoracic spine showed typical features of thoracic myelopathy: that is, sensory and motor deficits in both the trunk and lower extremities, sphincter disturbance, and exaggerated tendon reflexes. Several patients with involvement of the thoracolumbar junction presented with atypical symptoms of thoracic myelopathy and were sometimes misdiagnosed and treated inappropriately. Surgical treatment, particularly laminectomy, was not always successful. Inconsistencies in the surgical outcome were caused by either operative complications or reversal of the initial improvement during the follow-up period. The results of anterior surgery for the condition were more favorable; however, use of this procedure was rarely indicated.

Transforming DNA sequences in rat cells transformed by DNA fragments of highly oncogenic human adenovirus type 12

Rat cell lines tranformed by viral DNA fragments, EcoRI-C and HindIII-G, of adenovirus type 12 DNA were analyzed for the viral transforming DNA sequences present in cell DNAs. Cell lines transformed by the EcoRI-C fragment of adenovirus type 12 DNA (leftmost 16.5% of the viral genome) contain most of the HindIII-G sequences of the HindIII-G fragment, but at a different frequency depending on the portions of the fragment. The sequence of the AccI-H fragment of adenovirus type 12 DNA (the left part of the HindIII-G; leftmost 4.5% of the viral genome) was detected dominantly in cells transformed by the HindIII-G fragment Southern blot analysis showed that viral DNA sequences are present at multiple integration sites in high-molecular-weight cell DNA from cells transformed by the EcoRI-C or HindIII-G fragment of adenovirus type 12 DNA. These results suggest that most of the HindIII-G sequences in cells transformed by the HindIII-G fragment are present as fragmented forms.

Thioltrypsin. Chemical transformation of the active-site serine residue of Streptomyces griseus trypsin to a cysteine residue

The active-site serine residue of Streptomyces griseus trypsin was converted to a cysteine residue, and the product, thioltrypsin, was purified through two chromatographic steps with organomercurial-Sepharose and soybean trypsin inhibitor-Sepharose as specific adsorbents. The purified preparation of thioltrypsin was found to contain a single residue of cysteine and to react with almost equimolar amounts of normality titrants. It exhibited only traces of catalytic activity toward typical trypsin substrates such as Nalpha-tosyl-L-arginine methyl ester, whereas it retained some activity toward "active ester" substrates such as Nalpha-carbobenzoxy-L-lysine p-nitrophenyl ester. The activity was inhibited by sulfhydryl-blocking reagents, but no inhibition was observed by reagents reactive with the active hydroxyl group of serine proteases. Leupeptin, a natural trypsin inhibitor of peptidyl nature, also inhibited thioltrypsin. Some difference in the mode of leupeptin inhibition, however, was detected between trypsin and thioltrypsin. The bindings of small synthetic ligands and soybean trypsin inhibitor to thioltrypsin were compared with those to trypsin.