Relationships between Microbiome and Response to Neoadjuvant Chemoradiotherapy in Rectal Cancer

PURPOSE/OBJECTIVE(S)

Gut microbiome is known to be involved in antitumor immunotherapy and chemotherapy responses; however, few research has focused on the role of gut microbiome in the setting of concurrent chemoradiotherapy (CCRT). In this study, we investigated the tumor microbiome dynamics in patients undergoing neoadjuvant CCRT for locally advanced rectal cancer and sought to determine whether the diversity and composition of microbiome affect treatment response.

MATERIALS/METHODS

A total of 103 samples from 26 patients with locally advanced rectal cancer were collected and 16S ribosomal RNA amplicon sequencing was performed. All patients underwent neoadjuvant CCRT followed by surgical resection between 2008 and 2016. Samples were obtained from both tumor and normal rectal tissue at pre- and post-CCRT. According to the American Joint Committee on Cancer tumor regression grading (TRG) system, patients were divided into responders (TRG 0, 1) and non-responders (TRG 2, 3). We performed diversity, taxonomy, and network analyses to compare responders and non-responders. Then, we established the Bayesian network model to predict treatment response in patients with rectal cancer.

RESULTS

Overall, we detected 1260 microbial genera from 287 families, 132 orders, 56 classes, and 32 phyla in the bacteria kingdom. Between tumor and normal rectal tissues, there was no difference in microbial diversity and composition. On the other hand, there was a significant decrease in diversity and compositional alterations when comparing pre- and post-CCRT samples (all p<0.001). Ten patients (38.5%) were classified as responders and 16 patients (61.5%) were classified as non-responders. In both groups, CCRT significantly reduced microbial diversity and altered their composition, but it was more pronounced in non-responders. In taxonomic analysis of pre-CCRT samples, butyrate-producing bacteria were differentially enriched in responders. Meanwhile, in post-CCRT samples, opportunistic pathogen were overrepresented in non-responders. The network analysis revealed that butyrate-producing bacteria had strong interactions in responders, whereas opportunistic pathogen demonstrated strong interactions in non-responders (Pearson's coefficient>0.5). Finally, five microbes were selected as the optimal set for the response prediction model, which yielded an area under the curve value of 82.33%.

CONCLUSION

CCRT significantly changed the diversity and composition of microbiome, especially in non-responders. Several microbes might be related with treatment response. These findings highlight the potential of microbiome to play an important role as a biomarker in patients with rectal cancer. (NCT02533271).

The Early and Late Effects of High-Dose Irradiation on Cardiac Injury in a Rat Model

PURPOSE/OBJECTIVE(S)

Radiation-induced heart disease is a critical concern after radiotherapy (RT) for thoracic and chest wall tumors; however, the biological effects and mechanisms are still unknown. In this study, we investigated dose-responsive functional and pathological changes in rat hearts at 1, 3, and 5 months after high-dose irradiation. Then, we sought to elucidate the underlying mechanisms of myocardial changes induced by high-dose irradiation.

MATERIALS/METHODS

Whole hearts of rats (N = 72) were irradiated with a single fraction of 0 (control), 10, 20, or 30 Gy and allocated into three groups according to the follow-up period after RT: baseline, one, three, and five months. During follow-up periods, rats underwent functional evaluation by electrocardiogram and echocardiography at 4-week intervals. If a rat's body weight decreased by 20% or more, it was considered premature death, and the heart was explanted immediately. Otherwise, all hearts were explanted when each group's follow-up period was completed. Pathological changes of cardiac structures were evaluated using a light microscope after staining with hematoxylin-eosin, Masson's trichrome, α-smooth muscle actin, desmin, and connexin-43.

RESULTS

All rats irradiated with 0 or 10 Gy completed their follow-up periods with continuously increasing body weight. However, among rats irradiated with 20 or 30 Gy, half of the rats died prematurely at 8-10 weeks after RT, and the remainder survived until 20 weeks. In echocardiography, increased wall thickness and E/E' ratio, and decreased end-diastolic volume were observed in 20-30 Gy groups compared to 0-10 Gy groups from 8 weeks after RT. Ejection fraction was preserved in all groups. In pathological review, 20-30 Gy groups demonstrated diffuse inflammation and vacuolization at 4 weeks. Then, at 8 weeks, prominent fibrotic changes and intercalated disc disruptions were observed. Notably, fibrotic changes were somewhat resolved at 20 weeks, but intercalated disc disruptions were not repaired until 20 weeks. The 0 and 10 Gy groups showed no significant changes in both functional and pathological analyses.

CONCLUSION

Rats irradiated with 20 or 30 Gy showed diastolic dysfunction in functional analysis and time-dependent myocardial changes in pathological analysis. Radiation-induced fibrosis might be a "reactive" fibrosis, which could proceed to either a profibrotic course (progressive fibrosis) or an anti-fibrotic course (recovery phase). Further studies are needed to identify whether high-dose irradiation-induced cardiac fibrosis could be reversible.

Choosing Wisely between Radiotherapy Dose-Fractionation Schedules: The Molecular Graded Prognostic Assessment (molGPA) for Elderly Glioblastoma (eGBM-molGPA)

PURPOSE/OBJECTIVE(S)

This study aimed to develop a graded prognostic assessment (GPA) model integrating genomic characteristics in patients with elderly glioblastoma (eGBM), and compare the efficacy between conventionally fractionated radiotherapy (CFRT) vs. hypofractionated radiotherapy (HFRT) in each risk group.

MATERIALS/METHODS

Patients aged ≥65 years who underwent surgical resection followed by radiotherapy (RT) with or without temozolomide (TMZ) for newly diagnosed IDH-wildtype eGBM between 2006 and 2021 were included in this multicenter cohort study. Patients who were planned for a ≥6-week or ≤4-week radiotherapy were regarded as being treated with CFRT or HFRT, respectively. Based on the prognostic factors significantly identified through multivariate analysis for overall survival (OS), we developed the molecular GPA for eGBM (eGBM-molGPA) and assigned 0.0, 0.5, and 1.0 points in proportion to the corresponding hazard ratio (HR) of each factor. Then, the survival outcomes by treatment groups were evaluated according to the eGBM-molGPA scores.

RESULTS

A total of 334 and 239 patients who underwent CFRT and HFRT were included, respectively, and 86% of patients were treated with TMZ-based chemoradiation. With a median follow-up of 17.4 months for survivors, the median OS was 18.7 months for CFRT plus TMZ group, 15.1 months for HFRT plus TMZ group, and 10.4 months for RT alone group, respectively (all p<0.001). In the multivariate analysis, Karnofsky performance scale, surgical extent, TMZ, and the methylation status of the MGMT promoter were identified as strong prognostic factors for OS, with an estimated HR of greater than 1.5 (all p<0.001). Additionally, subventricular zone involvement, temporalis muscle thickness, RT regimen, and the mutation status of TERT promoter and TP53 gene were found to be significant prognostic factors for OS, with an estimated HR of less than 1.5. The eGBM-molGPA was established based on these prognostic factors (Table 1) and patients were allocated to three risk groups, which included high risk (total score of 3.0-4.5), intermediate risk (1.5-2.5), and low risk (0.0-1.0). Patients treated with CFRT plus TMZ had significantly improved OS compared to those treated with HFRT plus TMZ or RT alone in the low and intermediate risk groups (p<0.001). However, in the high-risk group, there was no significant difference in OS between treatment options (p = 0.770).

CONCLUSION

CFRT plus TMZ can be a more effective strategy for selected eGBM patients compared to HFRT. For high-risk patients, a protracted treatment schedule might not be beneficial. The novel eGBM-molGPA can be used as a clinical tool for choosing wisely among treatment options. Further prospective studies are warranted to establish optimal RT guidelines for eGBM patients.

Is a short arm cast appropriate for stable distal radius fractures in patients older than 55 years? A randomized prospective multicentre study

We conducted a prospective randomized, multicentre study to compare short arm and long arm plaster casts for the treatment of stable distal radius fracture in patients older than 55 years. We randomly assigned patients over the age of 55 years who had stable distal radius fracture to either a short arm or long arm plaster cast at the first review 1 week after their injury. Radiographic and clinical follow-up was conducted at 1, 3, 5, 12 and 24 weeks following their injury. Also, degree of disability caused by each cast immobilization was evaluated at the patient's visit to remove the cast. There were no significant differences in radiological parameters between the groups except for volar tilt. Despite these differences in volar tilt, neither functional status as measured by the Disabilities of the Arm, Shoulder and Hand, nor visual analogue scale was significantly different between the groups. However, the mean score of disability caused by plaster cast immobilization and the incidence rate of shoulder pain were significantly higher in patients who had a long plaster cast. Our findings suggest that a short arm cast is as effective as a long arm cast for stable distal radius fractures in the elderly. Furthermore, it is more comfortable and introduces less restriction on daily activities.

LEVEL OF EVIDENCE

II.

Effect of wrist position on the measurement of carpal indices on the lateral radiograph

The purpose of this study was to find out whether the carpal indices measured on lateral radiographs with a slightly malpositioned wrist are the same as those measured in the true neutral position. Lateral radiographic views of 25 wrists were taken with 5° intervals from 20° of flexion to 20° of extension. Most carpal indices measured in the flexed or extended position were significantly different from the wrist in zero flexion-extension, except scapholunate angle at 5° of extension and scaphocapitate angle at 5° and 10° of flexion. Starting from the flexed position, there was an average of -4.0° change in radioscaphoid angle, -1.0° in scapholunate angle, -1.0° in scaphocapitate angle, +3.0° in radiolunate angle, and +2.0° in lunocapitate angle for each 5° of extension with linear trends. The results from this study suggest that even minimal degrees of flexion-extension can affect the measurements of carpal indices on lateral radiographs.

Susceptibility of porcine keratocytes to immune-mediated damage in xeno-related rejection

We admixed cultured porcine keratocytes or corneal endothelial cells in the presence of human sera or peripheral blood mononuclear cells (PBMCs) for 4 to 72 hours to investigate their immune-related susceptibilities to xeno-related rejection. We evaluated complement deposition at 48 hours by flow cytometry after staining with the C3 anti-goat cy3 antibody. The inhibition of proliferation of porcine corneal cells by human sera was examined using the 3-[4,5-dimethy/thiazol-2,5-dephenyl tetrazolium bromide (MTT) assay over 24 to 72 hours. The amount of 51chromium (Cr)-release was estimated after a reaction between the porcine cells and human PBMCs for 4 hours. There was greater C3 deposition in keratocytes (60.2%) than in endothelial cells (26.9%; P = .05, Mann-Whitney U test). Both keratocytes and endothelial cells showed significant levels of proliferative inhibition over a period of 72 hours. The number of 51Cr-release cells on interleukin-2 addition was significantly higher among keratocytes (88.0%) than endothelial cells (51.4%) at a 1:100 target:effector ratio (P = .04, Mann-Whitney U test). Our present data suggested that porcine keratocytes might be key target cells in xeno-related rejections when the porcine cornea is transplanted to primates.

[4 + 3] Cycloaddition of cyclopropanone hemiacetals

[reaction: see text]. Intermolecular and intramolecular [4 + 3] cycloaddition reactions of readily available cyclopropanone hemiacetals with furans are described.

Light, carbon dioxide, and octenol-baited mosquito trap and host-seeking activity evaluations for mosquitoes in a malarious area of the Republic of Korea

Two field trials for commercially available and experimental mosquito traps variously baited with light, carbon dioxide, octenol, or combinations of these were evaluated in a malarious area at Paekyeon-Ri near Tongil-Chon (village) and Camp Greaves, Paju County, Kyonggi Province, Republic of Korea. The host-seeking activity for common mosquito species was determined using hourly aspirator collections from a human- and propane lantern-baited Shannon trap. The total number of mosquitoes and number of each species captured during the test were compared using 8 x 8 and 5 x 5 Latin square designs based on trap location. Significant differences were observed for the total number of mosquitoes collected in the 8 x 8 test, such that counterflow geometry (CFG) with CO2 > or = CFG with CO2 and octenol > or = Shannon trap > or = Mosquito Magnet with octenol > American Biophysics Corporation (ABC) light trap with light, CO2 (500 ml/min), and octenol > or = ABC light trap with light and dry ice > or = ABC light trap with light and CO2 > ABC light trap with light only. A concurrent 5 x 5 test found significant differences in trap catch, where Mosquito Magnet with octenol > New Jersey light trap > or = EPAR Mosquito Killer with CO2 > or = ABC light trap with light and dry ice > Centers for Disease Control (CDC) light trap (manufactured by John W. Hock) with light and octenol. Significant differences in trap catch were noted for several species including: Aedes vexans, Anopheles sinensis, An. yatsushiroensis, An. lesteri, Culex pipiens, and Cx. orientalis. Traps baited with octenol captured significantly fewer Cx. pipiens than those not baited with octenol. Likewise, no Cx. orientalis were captured in octenol-baited traps. Host-seeking activity showed a similar bimodal pattern for all species captured. Results from these field trap evaluations can significantly enhance surveillance efforts. Significantly greater numbers of mosquitoes were captured with mosquito traps using counterflow technology (e.g., Mosquito Magnet and CFG traps) when compared to standard light and carbon dioxide-baited traps. Additionally, field evaluations demonstrate that various traps can be utilized for isolation and detection of arboviruses and other pathogens.

Structure of the Ba-induced Si(111)- (3 x 2) reconstruction

The Ba/Si(111) surface, previously known as a 3 x 1 phase, is found to have a 3 x 2 periodicity and a semiconducting band gap. The substrate reconstructs into the honeycomb chain-channel (HCC) structure with Ba atoms in the channel, as in the alkali-metal-induced Si(111)-(3 x 1). However, the metal coverage is determined to be 1/6 monolayers, half the alkali-metal coverage. We propose that the structure and the metal coverage determined for the Ba adsorbate is universal for other alkaline-earth-metal adsorbates. With the alkali-metal-induced 3 x 1 case, our results lead to a rule that one donated electron per 3 x 1 surface unit is necessary to stabilize the HCC reconstruction of Si.

Malaria transmission potential by Anopheles sinensis in the Republic of Korea

To evaluate the factors that determine the transmission level of vivax malaria using vectorial capacity, entomological surveys were conducted from June to August, 2000. From 6 nights of human-bait collection in Paju, the human biting rate (ma) was counted as 87.5 bites/man/night. The parity of Anopheles sinensis from human baiting collections fluctuated from 41% to 71% (average 48.8%) of which the rate gradually increased as time passed on: 35.2% in Jun.; 55.0% in July; 66.2% in Aug. From this proportion of parous, we could estimate the probability of daily survival rate of An. sinensis to be 0.79 assumed with 3 days gonotrophic cycle and the expectancy of infective life through 11 days could be defined as 0.073. Blood meal analysis was performed using ELISA to determine the blood meal source. Only 0.8% of blood meals were from human hosts. We could conclude that An. sinensis is highly zoophilic (cow 61.8%). Malaria is highly unstable (stability index < 0.5) in this area. From these data, vectorial capacity (VC) was determined to be 0.081. In spite of a high human biting rate (ma), malaria transmission potential is very low due to a low human blood index. Therefore, we could conclude that malaria transmission by An. sinensis is resulted by high population density, not by high transmission potential. For this reason, we need more effort to decrease vector population and vector-human contact to eradicate malaria in Korea.

Visible light-induced degradation of carbon tetrachloride on dye-sensitized TiO2

This study investigated an application of TiO2 photocatalyst sensitized with tris(4,4'-dicarboxy-2,2'-bipyridyl)ruthenium-(II) complex to CCl4 degradation under visible light irradiation. By injecting electrons from the photoexcited sensitizer to the conduction band, the sensitized TiO2 degraded CCl4 under the irradiation of lambda > 420 nm. The quantum yield of CCl4 dechlorination was about 10(-3). The dechlorination rate of CCl4 was reduced in the presence of dissolved O2 due to its competition for conduction band electrons. The photolysis rate was dependent on pH due to the strong pH dependence of the sensitizer adsorption on TiO2 surface with a maximum degradation rate achieved at pH approximately 3. A two-site Langmurian model successfully described the adsorption of the sensitizer on TiO2 particles. The monolayer coverage was achieved at the added sensitizer concentration of 10 microM at [TiO2] = 0.5 g/L. However, the photolysis rate of CCl4 showed a maximum at a sensitizer surface coverage of 0.3 monolayer. Since the photoinduced electron injection gradually depleted active sensitizer molecules on TiO2, sacrificial electron donors to regenerate the sensitizer were sought. 2-Propanol as an electron donor was efficient in the present RuIIL3/TiO2/CCl4 system, which showed no sign of deceleration in the dechlorination rate up to 6 h of irradiation.

Evaluation of pH inhibition effect on activated sludge by the pseudo toxic concentration (CPT) concept model

It is generally accepted that the inhibition effect of pH on activated sludge follows the non-competitive inhibition kinetics. But the non-competitive inhibition kinetic equation cannot be directly applied to pH inhibition, due to the difficulty in quantification of pH as a term of inhibitor concentration. So, many empirical equations were developed especially for acidic condition to describe pH inhibition effect. In this research, the pseudo toxic concentration (CPT) concept model to quantify pH inhibition effect on activated sludge was proposed and compared with other existed models. Prediction of performance, presented by Prediction Accuracy and Prediction Accuracy Index, showed that the CPT concept model can explain the reduction of the maximum specific growth rate (mu max) more accurately than any other models do at a wide range of pH. The CPT concept model was applicable not only to activated sludge but also to specific microorganism groups, such as nitrifier, less acidophilic species and nitrifying biofilm.

Comparison of the BACTEC MGIT 960 and ESP culture system II for growth and detection of mycobacteria

The performances of two continuously monitoring mycobacterial culture systems-ESP Culture System II (ESP II; Trek Diagnostics, Inc. , Westlake, Ohio) and BACTEC MGIT 960 (BD Biosciences, Sparks, Md. )-were compared. In addition to both liquid media, all specimens were plated onto Middlebrook 7H11/7H11 selective agar. A total of 3, 151 specimens of all types (56.3% were respiratory specimens) were cultured; 231 (7.3%) yielded mycobacteria. The most common species recovered were Mycobacterium avium complex (69 isolates) and Mycobacterium tuberculosis complex (MTBC; 65 isolates). The recovery rates for ESP II, BACTEC MGIT 960, and Middlebrook agar, respectively, were 71.2, 63.9, and 61.8% for all mycobacteria; 70.2, 72.6, and 66.3% for all mycobacteria except Mycobacterium gordonae; and 73.8, 84.6, and 87.7% for MTBC. For liquid plus solid medium combinations, recovery rates for all mycobacteria and for MTBC, respectively, were 84.1 and 92.3% for ESP II plus Middlebrook agar and 81.5 and 98.5% for BACTEC MGIT 960 plus Middlebrook agar. The differences in recovery of all mycobacteria by ESP II and by BACTEC MGIT 960 were not significant; for the individual species, the only significant difference was recovery of more isolates of M. gordonae by ESP II. For those isolates recovered in both automated systems, mean times to detection of all mycobacteria and MTBC, respectively, were 15.8 and 17.4 days for ESP II and 12.5 and 11.9 days for BACTEC MGIT 960 (P < 0.05). False-positive signals occurred with 23 (0.7%) BACTEC MGIT 960 cultures and 84 (2.7%) ESP II cultures (P < 0.01). Overall contamination rates were 17.1% for BACTEC MGIT 960, 18.9% for ESP II, and 11.0% for Middlebrook agar. In summary, the ESP II and BACTEC MGIT 960 systems performed comparably with regard to growth and detection of mycobacteria, and the contamination rates were similar. However, with ESP II, times to detection of all mycobacteria and of MTBC were significantly longer, the recovery rate of M. gordonae was significantly higher, and the number of false-positive signals was greater than with BACTEC MGIT 960.

Investigation of exchange couplings in [Fe3S4]+ clusters by electron spin-lattice relaxation

We have studied four proteins containing oxidized 3Fe clusters ([Fe3S4]+, S=1/2, composed of three, antiferromagnetically coupled high-spin ferric ions) by continuous wave (CW) and pulsed EPR techniques: Azotobacter vinelandii ferredoxin I, Desulfovibrio gigas ferredoxin II, and the 3Fe forms of Pyrococcus furiosus ferredoxin and aconitase. The 35 GHz (Q-band) CW EPR signals are simulated to yield experimental g tensors, which either had not been reported, or had been reported only at X-band microwave frequency. Pulsed X- and Q-band EPR techniques are used to determine electron spin-lattice (T1, longitudinal) relaxation times at several positions on the samples' EPR envelope over the temperature range 2-4.2 K. The T1, values vary sharply across the EPR envelope, a reflection of the fact that the envelope results from a distribution in cluster properties, as seen earlier as a distribution in g3 values and in 57 Fe hyperfine interactions, as detected by electron nuclear double resonance spectroscopy. The temperature dependence of 1/T1 is analyzed in terms of the Orbach mechanism, with relaxation dominated by resonant two-phonon transitions to a doublet excited state at approximately 20 cm(-1) above the doublet ground state for all four of these 3Fe proteins. The experimental EPR data are combined with previously reported 57Fe hyperfine data to determine electronic spin exchange-coupling within the clusters, following the model of Kent et al. Their model defines the coupling parameters as follows: J13=J, J12=J(1+epsilon'), J23=J(1+epsilon), where Jij is the isotropic exchange coupling between ferric ions i and j, and epsilon' and epsilon' are measures of coupling inequivalence. We have extended their theory to include the effects of epsilon' not equal to 0 and thus derived an exact expression for the energy of the doublet excited state for any epsilon, epsilon'. This excited state energy corresponds roughly to epsilonJ and is in the range 5-10 cm(-1) for each of these four 3Fe proteins. This magnitude of the product epsilonJ, determined by our time-domain relaxation studies in the temperature range 2-4 K, is the same as that obtained from three other distinct types of study: CW EPR studies of spin relaxation in the range 5.5-50 K, NMR studies in the range 293-303 K, and static susceptibility measurements in the range 1.8-200 K. We suggest that an apparent disagreement as to the individual values of J and epsilon be resolved in favor of the values obtained by susceptibility and NMR (J > or approximately 200 cm(-1) and epsilon> or =0.02 cm(-1)). as opposed to a smaller J and larger r as suggested in CW EPR studies. However, we note that this resolution casts doubt on the accepted theoretical model for describing the distribution in magnetic properties of 3Fe clusters.

Ciliated foregut cyst of the gallbladder: a case report and review of the literature

A case is presented of a ciliated cyst of the gallbladder in a 36-year-old Korean woman which was incidentally found on ultrasonographic study. A cystic mass measuring 1.5 x 1 x 1 cm was found in the fundus of the gallbladder. The cyst was unilocular and intramural without communication to the lumen. Microscopically, the cyst wall was lined by a single layer of pseudostratified, ciliated, columnar epithelium and goblet cells with underlying smooth muscle layers. This was considered to be the cyst arising from the embryonic foregut and showing differentiation toward respiratory structures. The term 'ciliated foregut cyst of the gallbladder' is suggested here.

Reduced expression of the cell-cycle inhibitor p27Kip1 is associated with progression and lymph node metastasis of gastric carcinoma

AIMS

p27Kip1 (p27), a cyclin-dependent kinase inhibitor, plays an important role as inhibiting the progression of the cell cycle. Decreased expression of p27 is associated with high histological grade and aggressiveness of several human tumours. We aimed to evaluate the role of p27 in the progression and metastasis of gastric carcinoma.

METHODS AND RESULTS

We analysed the expression of p27 in 67 primary gastric carcinomas and 31 lymph node metastases by immunohistochemistry. Reduced expression of p27 was found more frequently in advanced gastric cancer (40.9%) than in early gastric cancer (15.6%) (P < 0.001). Decreased p27 expression correlated with large tumour size, high histological grade, lymphatic invasion, advanced stage, deep invasion, lymph node metastasis and recurrence. The expression of p27 showed an inverse correlation with the Ki67 labelling index. There was a significant reduction of p27 expression in metastatic tumour cells in lymph nodes (mean positive cells: 3. 7%) when compared to the corresponding primary gastric carcinomas (mean positive cells: 8.1%) (P = 0.008).

CONCLUSIONS

Alterations of p27 expression may play an important role in the progression and metastasis to lymph node of tumour cells in human gastric carcinoma.

Nitrogenase reduction of carbon disulfide: freeze-quench EPR and ENDOR evidence for three sequential intermediates with cluster-bound carbon moieties

Freeze-quenching of nitrogenase during reduction of carbon disulfide (CS(2)) was previously shown to result in the appearance of a novel EPR signal (g = 2.21, 1.99, and 1.97) not previously associated with any of the oxidation states of the nitrogenase metal clusters. In the present work, freeze-quench X- and Q-band EPR and Q-band (13)C electron nuclear double resonance (ENDOR) spectroscopic studies of nitrogenase during CS(2) reduction disclose the sequential formation of three distinct intermediates with a carbon-containing fragment of CS(2) bound to a metal cluster inferred to be the molybdenum-iron cofactor. Modeling of the Q-band (35 GHz) EPR spectrum of freeze-trapped samples of nitrogenase during turnover with CS(2) allowed assignment of three signals designated "a" (g = 2.035, 1.982, 1.973), "b" (g = 2.111, 2.002, and 1.956), and "c" (g = 2.211, 1. 996, and 1.978). Freezing samples at varying times after initiation of the reaction reveals that signals "a", "b", and "c" appear and disappear in sequential order. Signal "a" reaches a maximal intensity at 25 s; signal "b" achieves maximal intensity at 60 s; and signal "c" shows maximal intensity at 100 s. To characterize the intermediates, (13)CS(2) was used as a substrate, and freeze-trapped turnover samples were examined by Q-band (13)C ENDOR spectroscopy. Each EPR signal ("a", "b", and "c") gave rise to a distinct (13)C signal, with hyperfine coupling constants of 4.9 MHz for (13)C(a), 1. 8 MHz for (13)C(b), and 2.7 MHz for (13)C(c). Models for the sequential formation of intermediates during nitrogenase reduction of CS(2) are discussed.

Purification, cloning, and expression of a pathogen inducible UDP-glucose:Salicylic acid glucosyltransferase from tobacco

Salicylic acid (SA) plays an important role in plant disease resistance. Inoculation of tobacco leaves with incompatible pathogens triggers the biosynthesis of SA which accumulates primarily as the SA 2-O-beta-D-glucoside (SAG) and glucosyl salicylate (GS). The tobacco UDP-glucose:salicylic acid glucosyltransferase (SA GTase) capable of forming both SAG and GS was purified, characterized, and partially sequenced. It has an apparent molecular mass of 48 kDa, a pH optimum of 7.0, and an isoelectric point at pH 4.4. UDP-glucose was the sole sugar donor for the enzyme. However, SA and several phenolics served as glucose acceptors. The apparent K(m) values for UDP-glucose and SA were 0.27 and 1-2 mM, respectively. Zn(2+) and UDP inhibited its activity. The corresponding cDNA clone which encoded a protein of 459 amino acids was isolated from an SA-induced tobacco cDNA library and overexpressed in Escherichia coli. The recombinant protein catalyzed the formation of SAG and GS, and exhibited a broad specificity to simple phenolics, similar to that of the purified enzyme. Northern blot analysis showed that the SA GTase mRNA was induced both by SA and incompatible pathogens. The rapid induction timing of the mRNA by SA indicates that it belongs to the early SA response genes.

Facile synthesis of the tricyclic core of sarain A. 3-Oxidopyridinium betaine cycloaddition approach

[formula: see text] A new approach to a suitably functionalized tricyclic core of sarains has been developed by means of Katritzky's cycloaddition using 3-oxidopyridinium betaines. A key step was the regioselective differentiation of the two nearly identical hydroxy groups derived from oxidative cleavage of the double bond in 8 to afford 14. A stereocontrolled construction of the tricyclic core 20 of sarains containing the requisite side chain at C-3' was achieved by an intramolecular conjugate addition.

General analysis of (14)N (I = 1) electron spin echo envelope modulation

The analysis methods described to date for (14)N electron spin echo envelope modulation (ESEEM) mostly deal with isotropic g- and (14)N hyperfine coupling tensors. However, many cases of rhombic tensors are encountered. In the present report we present general equations for analyzing orientation-selective ESEEM and illustrate their use. (i) We present general equations for the nuclear interactions in an electron spin system where the EPR signal arises from an isolated Kramers doublet, then give the nuclear (electron-nuclear double resonance) frequencies for I = 1 associated with such a system. (ii) These are incorporated into equations for single-crystal ESEEM amplitudes, which in turn are incorporated into general equations for the orientation-selective ESEEM that arises when the EPR envelope of a frozen-solution (powder) sample is determined by g anisotropy. (iii) This development is first used in the simplest limit of an isotropic g-tensor and leads to a more general picture of the response of the I = 1 modulation amplitude to variations in the nuclear hyperfine and quadrupole coupling constants, relative to the nuclear Zeeman interaction, than had been presented previously. We find that strong modulation occurs not only in the well-known regime where the "exact/near cancellation" condition (A/2 approximately nu(N)) is satisfied, but also when the nuclear hyperfine interaction is much larger than the nuclear Zeeman interaction (A/nu(N) > 3) with A/K = 4 approximately 5. (iv) We then describe the orientation-selective (14)N ESEEM frequency-domain patterns (g vs frequency) in the presence of anisotropic (rhombic) hyperfine and electron Zeeman interactions for both coaxial and noncoaxial cases. We derive analytical solutions when the g-, hyperfine, and nuclear quadrupole tensors are coaxial. (v) The method is applied to the ESEEM of the nitrogenase MoFe protein (Av1) to determine the full hyperfine and nuclear quadrupole tensors of (14)N nuclei interacting with the S = 32 FeMo-cofactor (Fe(7)S(8)Mo: homocitrate).

14N electron spin-echo envelope modulation of the S = 3/2 spin system of the Azotobacter vinelandii nitrogenase iron-molybdenum cofactor

Wild-type nitrogenase MoFe protein shows a deep 14N electron spin-echo envelope modulation (ESEEM) arising from a nitrogen nucleus (N1) coupled to the S = 3/2 spin system of the FeMo-cofactor of the MoFe protein. A previous ESEEM study on altered MoFe proteins generated by substitutions at the alpha-195-histidine position suggested that alpha-195-histidine provides a hydrogen bond to the FeMo-cofactor but is not the source of the 14N1 modulation [DeRose et al. (1995) Biochemistry 34, 2809-2814]. This study also raised the possibility of a correlation between ESEEM spectroscopic properties and the nitrogenase phenotype. We now report ESEEM studies on altered MoFe proteins with substitutions at residues alpha-96-arginine, alpha-359-arginine, and alpha-381-phenylalanine to (i) assign the first-shell hydrogen bonding as revealed by the 14N modulation; (ii) explore the mechanistic relevance of the ESEEM signatures to nitrogenase activity; and (iii) study microscopic changes within the polypeptide environment of the FeMo-cofactor. Present ESEEM data reveals that two kinds of 14N modulations are present in wild-type MoFe protein. A new 2-dimensional procedure for high-precision analysis of the ESEEM data of the MoFe proteins shows that the deep wild-type ESEEM modulation (denoted N1) has a hyperfine-coupling constant of Aiso = 1.05 MHz and nuclear quadrupole coupling parameters of e2qQ = 2.17 MHz, eta = 0.59; the other (denoted N2) has a smaller hyperfine coupling of Aiso = approximately 0.5 MHz and e2qQ = approximately 3.5 MHz, eta = approximately 0.4. The N2 ESEEM pattern is more obvious when unmasked by substitutions that result in the loss of the deep N1 modulation. Correlations of the ESEEM properties and catalytic activities of the altered MoFe proteins suggest that (i) the side chain of the alpha-359-arginine is the source of the deep ESEEM N1 modulation; (ii) one or both of the amide nitrogens of alpha-356-glycine/alpha-357-glycine are responsible for the weak N2 modulation; (iii) substitution of the nonpolar alpha-381-phenylalanine residue, as well as substitution of either the alpha-195-histidine or alpha-359-arginine residues, can eliminate the N1 interaction with FeMo-cofactor; and (iv) ESEEM can be used to detect slight reorientations of FeMo-cofactor within its polypeptide pocket, although the mechanistic relevance of the loss or perturbation of the hydrogen-bonding interactions between FeMo-cofactor and polypeptide environment has not yet been established.

Glucosylation of Salicylic Acid in Nicotiana tabacum Cv. Xanthi-nc

ABSTRACT Salicylic acid (SA) is a key regulatory component of disease resistance in plants. In tobacco mosaic virus (TMV)-inoculated tobacco (Nicotiana tabacum cv. Xanthi-nc NN genotype), newly synthesized SA is converted primarily to SA 2-O-beta-D-glucoside (SAG) and glucosyl salicylate (GS), a relatively minor metabolite. Similar patterns in the formation of GS and SAG were observed in tobacco inoculated with Pseudomonas syringae pv. phaseolicola, suggesting the accumulation of two glucosylated metabolites is a general phenomenon in tobacco plants. After SA infiltration, GS was synthesized rapidly, reached a maximal level at 6 h, declined, and remained relatively constant for at least 24 h. In contrast, SAG content increased gradually after SA treatment. Our in vitro and in vivo data suggest that a high concentration of free SA triggers transient formation of GS and continuous accumulation of SAG, which is a more stable metabolite of SA. The two distinct SA glucosyltransferases catalyzed the formation of GS and SAG, respectively. The activities of these enzymes were enhanced by TMV or P. syringae pv. phaseolicola inoculation or SA treatment and were found in different fractions of gel filtration chromatography.

Prediction of common bile duct stones: its validation in laparoscopic cholecystectomy

BACKGROUND/AIMS

Although perioperative cholangiography is valuable and highly accurate in the detection of common bile duct (CBD) stones, its routine use is controversial, particularly in the era of the laparoscopic cholecystectomy because of its inherent disadvantages. The purposes of this retrospective and prospective study on cholelithiasis were to identify patients at low risk for CBD stones and to assess the validity of the low risk criteria.

METHODOLOGY

For the first, retrospective study, 15 significant preoperative clinical, biochemical and sonographic variables were selected from 561 consecutive patients who underwent conventional cholecystectomy with routine intraoperative cholangiography (IOC) for cholelithiasis from January 1985 to December 1993, and independent risk factors predicting the presence of CBD stones were determined by multivariate logistic regression analysis. For the second, prospective study, from April 1994 to September 1995, a laparoscopic cholecystectomy (LC) was performed without perioperative cholangiography in 153 consecutive patients with the primary low risk criterion (sonographic CBD diameter < 10 mm) determined by the first study. All of the LC patients were followed-up for a median duration of 12 months (range 4 to 21 months).

RESULTS

In the first study, CBD stones were present in 95 (16.9%) patients. The most important independent predictor was a dilated CBD (> 10 mm). Three levels of risk were determined: (1) the low risk group (73.8% of the patients), in which the CBD was not dilated and the prevalence of CBD stones was 1.5% (6/408); the moderate risk group (7.8% of the patients), in which there was a dilated CBD with normal liver function tests and a prevalence of stones of 48.8% (21/43); and the high risk group (18.4%), in which there was a dilated CBD and abnormal liver function tests and a prevalence of stones of 66.7% (68/102). In the second study, two cases (1.4%) of symptomatic overlooked CBD stones were found on endoscopic retrograde cholangiography and retrieved by endoscopic sphincterotomy on postoperative days 18 and 20, respectively.

CONCLUSIONS

Preoperative assessment in cases of cholelithiasis can determine which patients are at low risk for having CBD stones, thereby avoiding unnecessary perioperative cholangiography. This selectivity is also valid in LC, since the incidence of symptomatic, overlooked CBD stones was very low.

Familial juvenile polyposis coli with APC gene mutation

Familial juvenile polyposis has been known to have malignant potential, but their genetic relation to familial adenomatous polyposis has not been proven yet. Two young brothers with intermittent rectal bleeding revealed multiple juvenile polyposis. Their father had a history of rectal cancer with multiple colonic polyps. Four frequent exons of APC gene mutation were tested from these patients' white blood cells by polyacrylamide gel electrophoresis and sequencing. The 21-yr-old brother had a missense mutation (GAA-->GGA) at codon 1309, whereas the 18-yr-old brother showed a missense mutation (ATA-->GTA) at codon 1304 in exon 15 of APC gene. Three of four first-degree relatives were affected with familial juvenile polyposis, familial juvenile polyposis with adenomatous change, and rectal cancer with multiple polyps. The APC gene mutation of familial juvenile polyposis in this case suggests a genetic relationship with familial adenomatous polyposis.

Prohevein is poorly processed but shows enhanced resistance to a chitin-binding fungus in transgenic tomato plants

In latex of rubber tree (Hevea brasiliensis), prohevein, homologous to potato win gene-encoded proteins, is processed to yield mature hevein. This mature hevein is composed of one chitin-binding domain and the C-terminal polypeptide homologous to pathogenesis-related proteins such as tobacco PR-4 and tomato P2 proteins. In contrast, prohevein was poorly cleaved to form the C-terminal polypeptide in transgenic tomato plants expressing hevein gene (HEV1)-driven polypeptides. However, mature hevein, the N-terminal cleavage form, was not found in this system. Immunoblot analysis of extracellular and intracellular fluid proteins showed that HEV1-encoded polypeptides accumulated intracellularly. In addition, retardation of growth of Trichoderma hamatum was observed in transgenic tomatoes constitutively expressing HEV1-encoded proteins.

Biosynthesis and metabolism of salicylic acid

Pathways of salicylic acid (SA) biosynthesis and metabolism in tobacco have been recently identified. SA, an endogenous regulator of disease resistance, is a product of phenylpropanoid metabolism formed via decarboxylation of trans-cinnamic acid to benzoic acid and its subsequent 2-hydroxylation to SA. In tobacco mosaic virus-inoculated tobacco leaves, newly synthesized SA is rapidly metabolized to SA O-beta-D-glucoside and methyl salicylate. Two key enzymes involved in SA biosynthesis and metabolism: benzoic acid 2-hydroxylase, which converts benzoic acid to SA, and UDPglucose:SA glucosyltransferase (EC 2.4.1.35), which catalyzes conversion of SA to SA glucoside have been partially purified and characterized. Progress in enzymology and molecular biology of SA biosynthesis and metabolism will provide a better understanding of signal transduction pathway involved in plant disease resistance.

Immunogenicity and protective efficacy of solubilized merozoite-enriched Theileria sergenti immunogens. III. Characterization of immunodominant peptides

Immunoblot analysis utilizing bovine sera from naturally or experimentally infected with Theileria sergenti were used to determine the immunodominant polypeptides of T. sergenti (Korean isolate). The previously recognized major bands, 18 kDa, 29 kDa, 34 kDa and 45 kDa, were excised after electrophoresis and transfer to PVDF membrane. The individual bands were sequenced. The 34 kDa polypeptide which was the most antigenic and immunogenic peptide was observed in the Western blot. However, Chou-Fasman prediction sites (antigenic site) for antigen determinants of the 45 kDa, 24 kDa, 29 kDa and 18 kDa polypeptide were 6, 4, 2 and 0, respectively. However, the 45 kDa polypeptide showed no reaction with anti-T, sergenti hyperimmune serum.

The Arabidopsis endoplasmic reticulum retention receptor functions in yeast

Soluble proteins retained in the lumen of the endoplasmic reticulum (ER) contain a carboxyl-terminal tetrapeptide sequence that functions presumably to recycle these proteins from a subsequent compartment. Biochemical and genetic evidence indicate that the ERD2 gene product is the receptor for these ER retention signals. Here we report the identification of a cDNA clone from Arabidopsis thaliana (aERD2) similar in sequence and size to members of the ERD2 gene family. Southern and Northern blot analyses indicate that Arabidopsis contains a single aERD2 gene which is expressed at different levels in various plant tissues. A functional assay demonstrates that the Arabidopsis homologue, unlike the mammalian protein, can complement the lethal phenotype of the erd2 deletion mutant of Saccharomyces cerevisiae, indicating that this protein may have a similar function in plants. As the plant protein may have a binding specificity similar to the human Erd2 protein but can function in yeast, we suggest that the plant homologue is the functional link between yeast and animals.

Co- and post-translational processing of the hevein preproprotein of latex of the rubber tree (Hevea brasiliensis)

Hevein is a chitin-binding protein of 43 amino acids found in the lutoid body-enriched fraction of rubber tree latex. A hevein cDNA clone (HEV1) (Broekaert, W., Lee, H.-i., Kush, A., Nam, C.-H., and Raikhel, N. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 7633-7637) encodes a putative signal sequence of 17 amino acids followed by a polypeptide of 187 amino acids. Interestingly, this polypeptide has two distinct domains: an amino-terminal domain of 43 amino acids, corresponding to mature hevein, and a carboxyl-terminal domain of 144 amino acids. To investigate the mechanisms involved in processing of the protein encoded by HEV1, three domain-specific antisera were raised against fusion proteins harboring the amino-terminal domain (N domain), carboxyl-terminal domain (C domain), and both domains (NC domain). Translocation experiments using an in vitro translation system show that the first 17-amino acid sequence encoded by the cDNA functions as a signal peptide. Immunoblot analysis of proteins extracted from lutoid bodies demonstrates that a 5-kDa protein comigrated with purified mature hevein and cross-reacted with N domain- and NC domain-specific antibodies. A 14-kDa protein was recognized by C domain- and NC domain-specific antibodies. A 20-kDa protein was cross-reactive with all three antibodies. Microsequencing data further suggest that the 5-kDa (amino-terminal domain) and 14-kDa (carboxyl-terminal domain) proteins are post-translational cleavage products of the 20-kDa polypeptide (both domains) which corresponds to the proprotein encoded by HEV1. In addition, it was found that the amino-terminal domain could provide chitin-binding properties to a fusion protein bearing it either amino terminally or carboxyl terminally.

Wound-induced accumulation of mRNA containing a hevein sequence in laticifers of rubber tree (Hevea brasiliensis)

Hevein is a chitin-binding protein that is present in laticifers of the rubber tree (Hevea brasiliensis). A cDNA clone (HEV1) encoding hevein was isolated by using the polymerase chain reaction with mixed oligonucleotides corresponding to two regions of hevein as primers and a Hevea latex cDNA library as a template. HEV1 is 1018 base pairs long and includes an open reading frame of 204 amino acids. The deduced amino acid sequence contains a putative signal sequence of 17 amino acid residues followed by a 187-amino acid polypeptide. This polypeptide has two striking features. The amino-terminal region (43 amino acids) is identical to hevein and shows homology to several chitin-binding proteins and to the amino termini of wound-inducible proteins in potato and poplar. The carboxyl-terminal portion of the polypeptide (144 amino acids) is 74-79% homologous to the carboxyl-terminal region of wound-inducible genes of potato. Wounding, as well as application of the plant hormones abscisic acid and ethylene, resulted in accumulation of hevein transcripts in leaves, stems, and latex but not in roots.