Municipal wastewater monitoring revealed the predominance of bla GES genes with diverse variants among carbapenemase-producing organisms: high occurrence and persistence of Aeromonas caviae harboring the new bla GES variant bla GES-48

IMPORTANCE

The emergence and spread of carbapenemase-producing organisms (CPOs) represent a global health threat because they are associated with limited treatment options and poor clinical outcomes. Wastewater is considered a hotspot for the evolution and dissemination of antimicrobial resistance. Thus, analyses of municipal wastewater are critical for understanding the circulation of these CPOs and carbapenemase genes in local communities, which remains scarcely known in Japan. This study resulted in several key observations: (i) the vast majority of bla GES genes, including six new bla GES variants, and less frequent bla IMP genes were carbapenemase genes encountered exclusively in wastewater influent; (ii) the most dominant CPO species were Aeromonas spp., in which a remarkable diversity of new sequence types was observed; and (iii) CPOs were detected from combined sewer wastewater, but not from separate sewer wastewater, suggesting that the load of CPOs from unrecognized environmental sources could greatly contribute to their detection in influent wastewater.

Zoonotic potential and antimicrobial resistance of Escherichia spp. in urban crows in Japan-first detection of E. marmotae and E. ruysiae

Little is known about the prevalence of antimicrobial-resistant bacteria and pathogenic Escherichia coli in crows (carrion and jungle crows). We studied the phylogeny, virulence and antimicrobial resistance gene profiles of crow E. coli isolates to investigate their zoonotic potential and molecular epidemiology. During the winter of 2021-2022, 34 putative E. coli isolates were recovered from 27 of the 65 fresh fecal samples collected in urban areas. Three strains of the B1-O88:H8-ST446-fimH54 lineage, classified as extraintestinal pathogenic E. coli (ExPEC) and necrotoxigenic E. coli type 2, were colistin-resistant and harbored mcr-1.1-carrying IncI2 plasmids. The blaCTX-M-55 was identified in a multidrug-resistant B1-O non-typeable:H23-ST224-fimH39 strain. In phylogroup B2, two lineages of O6:H1-ST73-fimH30 and O6:H5-ST83-fimH21 were classified as ExPEC, uropathogenic E. coli, and necrotoxigenic E. coli type 1 (O6:H5-ST83-fimH21), and contained several virulence genes associated with avian pathogenic E. coli. Noteworthy is that three isolates, identified as E. coli by MALDI-TOF MS, were confirmed to be two Escherichia marmotae (cryptic clade V) and one Escherichia ruysiae (cryptic clade III) based on ANI and dDDH analyses. Our results provide the first evidence of these new species in crows. E. marmotae and E. ruysiae isolates in this study were classified as ExPEC and contained the enteroaggregative E. coli heat-stable toxin 1 gene. In addition, these two E. marmotae isolates displayed a close genetic relationship with human isolates associated with septicemia. This study provides the first insights into the prevalence and zoonotic significance of Escherichia spp. in urban crows in Japan, posing a significant risk for their transmission to humans.

Monobody adapter for functional antibody display on nanoparticles for adaptable targeted delivery applications

Vascular endothelial cells (ECs) play a central role in the pathophysiology of many diseases. The use of targeted nanoparticles (NPs) to deliver therapeutics to ECs could dramatically improve efficacy by providing elevated and sustained intracellular drug levels. However, achieving sufficient levels of NP targeting in human settings remains elusive. Here, we overcome this barrier by engineering a monobody adapter that presents antibodies on the NP surface in a manner that fully preserves their antigen-binding function. This system improves targeting efficacy in cultured ECs under flow by >1000-fold over conventional antibody immobilization using amine coupling and enables robust delivery of NPs to the ECs of human kidneys undergoing ex vivo perfusion, a clinical setting used for organ transplant. Our monobody adapter also enables a simple plug-and-play capacity that facilitates the evaluation of a diverse array of targeted NPs. This technology has the potential to simplify and possibly accelerate both the development and clinical translation of EC-targeted nanomedicines.

Presence of Colistin- and Tigecycline-Resistant Klebsiella pneumoniae ST29 in Municipal Wastewater Influents in Japan

The aim of this study was to investigate the presence of colistin- and/or tigecycline-resistant Klebsiella spp. in influents from four wastewater treatment plants (WWTPs), which partly reflect the gut microbiome of human populations. Colistin- and tigecycline-resistant Klebsiella pneumoniae isolates (K30/ST29) were detected four times from the WWTP A during a period of 3 months. Disruptions of the mgrB and ramR genes by ISEc68 and ISKpn21, respectively, were identified in those four isolates. They also shared the IncL/M 86,197-bp plasmids carrying a bla_CTX-M-3 and Tn1548-associated armA [IS26-IntI1-dfrA12-gucF-aadA2-qacEΔ1-sul1-ISCR1-ISEc28-armA-ISEc29-msr(E)-mph(E)-IS26]. Those isolates formed a distinct cluster within wgMLST clusters of ST29 K30 public reference strains of human origin and were unique due to harboring of Tn21-like mercury resistance operon transposons in addition to silver, copper, and arsenic resistance determinants. Five K. pneumoniae strains with different STs and 1 Klebsiella quasipneumoniae strain, exhibiting colistin resistance, were detected in WWTPs B, C, and D. For these isolates, disruptions of mgrB by ISEc68 (three isolates) or ISEcl1 (one isolate), insertion of IS2 in the mgrB promoter region (one isolate), and inactivation of MgrB by a nonsense mutation (one isolate) were identified. Close monitoring of these mcr-negative colistin- and/or tigecycline-resistant bacteria in wastewater influents is imperative to avoid further limiting of treatment options.

Genomic characterisation and epidemiology of nosocomial Serratia marcescens isolates resistant to ceftazidime and their plasmids mediating rare blaTEM-61

OBJECTIVES

We determined the whole DNA sequences of plasmids carrying a rare extended-spectrum β-lactamase gene (bla_TEM-61) to precisely understand the spread of resistance among nosocomial Serratia marcescens populations.

METHODS

Twenty non-duplicate ceftazidime-resistant S. marcescens nosocomial isolates (ceftazidime MICs, 32 to >128 mg/L) collected over 1 year were pulsotyped and nucleotide sequences of the bla_TEM-61 gene and its promoter region were determined. Twelve representative isolates were analysed by whole-genome sequencing.

RESULTS

The 20 isolates comprised two distinct pulsotypes: I (14 isolates) and II (6 isolates). They all contained the bla_TEM-61 gene. A polymorphism in the repeat number of a 15-nucleotide sequence (5'-ATGTCATGATAATAA-3') was found in the promoter region of bla_TEM-61; two, three and four repeat units were found in 6, 12 and 2 isolates, respectively. Single nucleotide polymorphism (SNP)-based phylogenetic analysis of 12 isolates revealed that 7 isolates of pulsotype I (12-44 SNP differences) and 5 isolates of pulsotype II (15-55 SNP differences) formed two distinct clusters of genotypes 1 and 2, respectively. All 12 isolates harboured a plasmid carrying the Tn1-bla_TEM-61 element, although they were slightly different in size (78 883 bp, 78 898 bp and 78 913 bp) owing to differences in the number of 15-bp repetitive sequences. A 42 542-bp broad-host-range plasmid carrying the Tn1-bla_TEM-61 element was also found in one of the isolates.

CONCLUSIONS

We characterised a plasmid-encoded novel Tn1-bla_TEM-61 element and transposon-dependent mechanisms underlying the propagation of antibiotic resistance, together with repeated new polymorphic 15-bp units in the promoter of bla_TEM-61.

Predominance of methicillin-resistant Staphylococcus aureus SCCmec type II-CC5 and SCCmec type IV-CC1/CC8 among companion animal clinical isolates in Japan: Findings from phylogenetic comparison with human clinical isolates

OBJECTIVES

To characterise the genotypic profiles of methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates from companion animals and to investigate their association with those from humans in Japan.

METHODS

Non-duplicated MRSA clinical isolates recovered between July 2016 and January 2018 were analysed. The MRSA isolates were typed by polymerase chain reaction (PCR)-based open reading frame (ORF) typing (POT) scores, SCCmec types, multilocus sequence typing, and virulence gene profiles. Phylogenetic comparison of those isolates with previously described human isolates was performed.

RESULTS

Among 56 MRSA isolates (33 cats, 20 dogs and three rabbits), 26 isolates with a POT1 score of 93, SCCmec type II mostly belonged to CC5, including ST5. Twenty-six isolates with a POT1 score of 106, SCCmec type IV showed diversity of STs: 15 isolates belonged to CC8, mainly including ST8, and 11 isolates belonged to CC1, including ST1 and newly identified STs 4768, 4775, and 4779. Two cat isolates were ST8-SCCmec type IV possessing pvl/ACME-arcA, presumed to be the hypervirulent community-associated MRSA (CA-MRSA) clone USA300. Notably, all three rabbit isolates belonged to ST4768. The POT1 score 106 CA-MRSA isolates from animals and humans were divided into two large clusters of CC1 and CC8, where host species-specific sub-clusters were not identified within each cluster. A large cluster of POT1 score 93 healthcare-associated MRSA (HA-MRSA) isolates from animals and humans consisted of sub-clusters formed exclusively by the vast majority of human isolates and those formed by animal and human isolates.

CONCLUSION

Companion animals could be potential reservoirs and vehicles for the transmission of CA-MRSA to humans, and could transmit companion animal-adaptive HA-MRSA lineages to humans as their second reservoirs.

Diffuse pollution monitoring and modelling of small urban watershed in Brazil Cerrado

The stormwater runoff carries different pollutants that can reduce the quality of receiving waters due to diffuse pollutant loads. This research was aimed at evaluating the concentration of pollutants in stormwater and the application of SWMM (Storm Water Management Model) to an urban catchment in Lake Paranoá watershed to carry out the simulation of flow discharge with the hydraulic model, and subsequently to estimate the loads conveyed to the lake in ordinary events of precipitation. This study was carried out based on rainfall and runoff monitoring during events. It was confirmed that this model's results fit well in simulation of this type of watershed, leading to high value of the Nash-Sutcliffe coefficient after calibration but, as expected, precipitation distribution is a very important factor for calibration. Concerning water quality, it was observed that the event mean concentration values of suspended solids and chemical oxygen demand were high, indicating that the diffuse pollution is an important source of pollution of the receiving waters. The monitoring and modelling of stormwater are essential to identify diffuse pollution discharge, in searching for a sustainable solution.

Potential effect of selective pressure with different β-lactam molecules on the emergence of reduced susceptibility to β-lactams in group B Streptococci

In this study, the selective potential of group B Streptococcus isolates with reduced penicillin susceptibility (PRGBS) in a neonate-hypervirulent sequence type (ST)17 lineage was investigated by in vitro exposure to β-lactams. After 19 passages of stepwise penicillin exposure, PRGBS with a high penicillin minimum inhibitory concentration MIC (0.5 mg/L), greatly augmented ceftibuten MIC (>512 mg/L), and acquisition of G406D predicted to provide destabilizing effect (ΔΔG 0.099 kcal/mol) on PBP2X structure were identified. In early passages of stepwise cefotaxime exposure, PRGBS possessing G398E predicted to stabilize PBP2X (ΔΔG -0.038 kcal/mol) emerged with high MICs for cefotaxime (0.5 mg/L), ceftibuten (>512 mg/L) and penicillin (0.25 mg/L). Additionally, G398E + G329V + H438Y predicted to provide more stabilizing effect (ΔΔG -0.415 kcal/mol) were detected in mutants with higher MICs to cefotaxime (1 mg/L) and penicillin (0.5 mg/L). PRGBS mutants selected by penicillin and cefotaxime had a marked growth disadvantage compared with the parent strain. After two passages of stepwise ceftibuten exposure, the mutants exhibited increased MICs toward ceftibuten and acquisition of T555S predicted to provide stabilizing effect (ΔΔG -0.111 kcal/mol) in PBP 2X. In subsequent passages, gradual increases in ceftibuten MICs from 128 mg/L to 512 mg/L were found among selected mutants with accompanying stabilizing T555S+A354V (ΔΔG -0.257 kcal/mol) followed by stabilizing T555S + A354V + A536V (ΔΔG -0.322 kcal/mol), resulting in selection of a penicillin-susceptible group B Streptococcus lineage with reduced ceftibuten susceptibility (CTB^r PSGBS). Notably, growth ability of CTB^r PSGBS mutants was comparable to that of the parent strain. These findings may predict future failure of treatment for neonatal invasive infections caused by the neonate-hypervirulent PRGBS ST17 lineage.

Population-level transition of capsular polysaccharide types among sequence type 1 group B Streptococcus isolates with reduced penicillin susceptibility during a long-term hospital epidemic

Over a 35-month period, group B Streptococcus isolates with reduced penicillin susceptibility (PRGBS) were detected from elderly patients at a regional hospital in Japan, accompanying population-level transition of PRGBS serotypes. The genetic relatedness of 77 non-duplicate PRGBS from 73 patients was analysed. Serotype III PRGBS predominated (16 serotype III/1 serotype Ib) in the first 9 months (period I), then 3 serotype Ib isolates appeared transiently for the next 3 months (period II), which was replaced predominantly by serotype Ia (20 serotype Ia/1 serotype III/1 non-typeable) for 9 months (period III). In the last 14 months (period IV), besides 25 serotype Ia isolates, 10 serotype III were also identified. Serotypes III and Ia isolates, belonging to ST1, shared G329V, G398A, V405A and G429D substitutions in penicillin-binding protein 2X. Of three strains subjected to whole-genome sequencing, serotype III strain SU12 (period I) had a higher degree of genomic similarity with serotype Ia strain SU97 (period III) than serotype Ib strain SU67 (period II) based on average nucleotide identity and single nucleotide polymorphisms. Analysis of the cps gene clusters and the upstream and downstream flanking sequences revealed that disruption of the hyaluronidase gene located upstream of cpsY by insertion of IS1548 was found in strain SU12, whereas ΔISSag8 was inserted between tRNA-Arg and rpsA genes located downstream of cpsL in strain SU97. Interestingly, most serotype III PRGBS re-emerging in period IV had this tRNA-Arg-ΔISSag8-rpsA region. Capsular switching and nosocomial transmission may possibly contribute to population-level serotype replacement among ST1 PRGBS isolates.

MASTDISCS combi Carba plus, a simple method for discriminating carbapenemase-producing Enterobacteriaceae, including OXA-48-type producers

Accurate and rapid detection of carbapenemases and identification of their types in Enterobacteriaceae are both still major challenges for clinical laboratories in attempting to prevent the intrusion and transmission of carbapenemase-producing Enterobacteriaceae. This study aimed to evaluate the performance of the MASTDISCS combi Carba plus disc system in identification of different carbapenemase types, including OXA-48-type carbapenemase, for which no specific enzyme inhibitors have so far been available. The simple disc system discriminates carbapenemases, including OXA-48-types exhibiting low carbapenem minimum inhibitory concentrations, by targeting Enterobacteriaceae isolates with a EUCAST meropenem screening cut-off of ≥0.25 mg/L.

Prevalence of ESBL/AmpC genes and specific clones among the third-generation cephalosporin-resistant Enterobacteriaceae from canine and feline clinical specimens in Japan

In recent years, besides the widespread occurrence of extended-spectrum β-lactamase (ESBL)- and/or plasmid-mediated AmpC (pAmpC)-producing Enterobacteriaceae in both healthcare and community settings of humans, the third-generation cephalosporin (3GC)-resistant microbes have also been reported from companion animals worldwide. Here, we characterized ESBL- and/or pAmpC-producing Enterobacteriaceae clinical isolates from companion animals. Among the 487 clinical isolates mainly from urine of dogs and cats between May and September 2016, 104 non-repetitive isolates were resistant to the 3GC, and they consisted of 81 of 381 (21.3%) Escherichia coli, 21 of 50 (42.0%) Klebsiella pneumoniae, and 2 of 56 (3.6%) Proteus mirabilis isolates. In the 81 E. coli, the predominant bla genes were bla_CTX-M-27 and bla_CMY-2 (n = 15 each), followed by bla_CTX-M-15 (n = 14), bla_CTX-M-14 (n = 10), and bla_CTX-M-55 (n = 5). In 21 K. pneumoniae, 10 bla gene types including bla_CTX-M-15 (n = 4), bla_CTX-M-2 (n = 4), and bla_CTX-M-14 (n = 3) were found. The bla_CTX-M-2 was identified in 2 P. mirabilis. Twenty-four of the 42 E. coli belonging to phylogroup B2 were O25b-ST131 clone, mostly associated with uropathogenic E. coli pathotype, and 22 isolates of this clone were identified as specific H30R subclone. High prevalence of the bla_CTX-M-27-harboring isolates were noted among the H30R/non-Rx lineage (13/19, 68.4%) (p <  0.05). The genetic environment of bla_CTX-M-27 of most isolates of this lineage was identical to that of human isolates, but unique flanking genetic structures were also identified. Newly emerging virulent lineage B2-non-O25b-ST1193 was also confirmed in 5 isolates. The fosA3 and/or armA genes were detected in E. coli and K. pneumoniae isolates. These data suggest that companion animals serve as a potential reservoir of antimicrobial resistant E. coli and K. pneumoniae. This also has considerable veterinary importance, since urinary tract infections are an important disease causing therapeutic challenges worldwide.

Genetic shifts in methicillin-resistant Staphylococcus aureus epidemic clones and toxin gene profiles in Japan: comparative analysis among pre-epidemic, epidemic and post-epidemic phases

PURPOSE

The decline in methicillin-resistant Staphylococcus aureus (MRSA) isolation rates has become a general observation worldwide, including Japan. We hypothesized that some genetic shift in MRSA might cause this phenomenon, and therefore we investigated the genetic profiles among MRSA clinical isolates obtained from three different epidemic phases in Japan.

METHODOLOGY

A total of 353 MRSA isolates were selected from 202 medical facilities in 1990 (pre-epidemic phase), 2004 (epidemic phase) and 2016 (post-epidemic phase). Molecular typing was performed by PCR detection of 22 genes using the polymerase chain reaction (PCR)-based ORF typing (POT) system, including an additional eight genes including small genomic islets and seven toxin genes.

RESULTS

Isolates with a POT1 of score 93, identified as presumed clonal complex (pCC)5-staphylococcal cassette chromosome mec (SCCmec) type II including ST5-SCCmec type II New York/Japan clone, represented the major epidemic MRSA lineage in 1990 and 2004. In 2016, however, a marked decrease in isolates with a POT1 score of 93, along with changes in the epidemiology of toxin genes carried, was noted, where the carriers of tst genes including the tst-sec combination were markedly reduced, and those possessing the seb gene alone were markedly increased. Rather, isolates with a POT1 score of 106, including pCC1 or pCC8 among the isolates with SCCmec type IV, which often links to community-associated MRSA, were predominant. Interestingly, the pCC1 and pCC8 lineages were related to sea and tst-sec carriage, respectively.

CONCLUSIONS

Over time, a transition in MRSA genetic profiles from a POT1 score of 93 in 1990 and 2004 to 106 in 2014 was found in Japan.

First Detection of an Escherichia coli Strain Harboring the mcr-1 Gene in Retail Domestic Chicken Meat in Japan

Global spread of the plasmid-mediated colistin resistance gene, mcr-1 poses a challenge to public health because colistin is the last-line-of-defense against severe infections of multidrug-resistant Gram-negative bacteria. In Japan, a few studies have reported the prevalence of mcr-1 among food animal-derived Escherichia coli isolates, but the prevalence of mcr-1 in retail meats is not well known. We report here the first detection of mcr-1 in retail chicken meat. A total of 70 extended-spectrum beta-lactamase-producing E. coli isolates, recovered from retail chicken meats between August 2015 and June 2016, were screened for mcr-1. We found 1 CTX-M-1 beta-lactamase-producing E. coli isolate belonging to ST1684, phylogroup A. The mcr-1 gene was not located on an IncI1 plasmid encoding the bla_CTX-M-1 gene. However, whole plasmid sequencing revealed that mcr-1 was located on an IncI2 plasmid. The sequences of the nikB-mcr-1-pap2-ydfA-topB region of the IncI2 plasmid in this study was almost identical to that of the previously described IncI2 plasmid, pECJS-61-63 present in E. coli isolated from pig feces in China, except for containing a synonymous mutation in the mcr-1 gene. Plasmid carrying the mcr-1 gene have not yet been identified in human isolates in Japan. Thus, strict monitoring or surveillance of colistin resistance among Gram-negative bacteria recovered from retail meat of food animals under colistin pressure, and humans, is crucial.

Kidney Transplantation, Cardiovascular Risk, and Long-Term Dialysis in Japan

BACKGROUND

The waiting time for deceased-donor kidney-only transplantations in Japan is long. Herein, we assessed the effect of length of dialysis on the outcomes of these patients.

METHODS

We divided patients into 2 groups based on length of dialysis (Group A, <15 years, and Group B, ≥15 years), and compared the background and outcomes after kidney transplantation.

RESULTS

Group A included 210 patients and Group B included 35 patients. In Group B, 20% of transplants were from living donors. Patient age (P = .017) and the hepatitis C infection rate (P = .018) were significantly higher in Group B, whereas hypertension (P = .011), diabetes (P = .041), and ABO-incompatibility rates (P = .015) were significantly higher in Group A. The 5- and 10-year survival rates were 97.0% and 95.4%, respectively, in Group A and 97.1% and 97.1%, respectively, in Group B. The 5- and 10-year graft survival rates were 95.4% and 84.8%, respectively, in Group A and 97.1% and 73.1%, respectively, in Group B. There were no significant differences between the groups in patient survival (P = .74) and graft survival (P = .72). The 5- and 10-year cardiovascular event-free survival rates were 95.9% and 92.4%, respectively, in Group A and 88.6% and 76.8%, respectively, in Group B. Cardiovascular event-free survival was significantly higher in Group A (P = .038). Cox stepwise multivariate analysis indicated that length of dialysis was a significant predictor of cardiovascular events (hazard risk, 1.007; range, 1.001-1.012; P = .012).

CONCLUSION

The prognosis after kidney transplantation is promising even after a long length of dialysis, although evaluation of the cardiovascular risk is needed in these cases.

A randomized 'N-of-1' single blinded clinical trial of barbed dermal sutures vs. smooth sutures in elective plastic surgery shows differences in scar appearance two-years post-operatively

BACKGROUND

Barbed sutures have unidirectional circumferential shallow barbs, which distribute tension throughout the wound and close wound securely without the need to tie knots.

OBJECTIVES

We compare two different methods of wound closure in elective plastic surgical cases: barbed 3/0 V-Loc™180 suture and smooth 3/0 Maxon™ sutures, both polyglyconate monofilament synthetic absorbable sutures. We assessed the aesthetic long-term results with a minimum two year follow up.

METHODS

This is a prospective, randomized controlled study with internal control. A single surgeon performed all cases. Patients who underwent elective operations that involved long wound closure were enrolled in the study. Each patient acted as their own internal control with half their wound being sutured with 3/0 V-Loc™180 barbed suture and the other half with smooth 3/0 Maxon™ deep dermal sutures and then a subcuticular skin closure. In both groups, the superficial fascial system was closed with 1 Vicryl interrupted sutures on both sides. Long-term cosmesis was evaluated using the modified Hollander cosmesis score by review of standardized postoperative photographs by 9 blinded plastic surgeons and specialist registrars.

RESULTS

The study reports on 33 female patients. The time taken for wound closure was significantly reduced using the barbed suture (p < 0.001). There was no difference in the complication ratio in either group. Two-year aesthetic outcome was significantly superior when using the barbed suture (p = 0.0075).

CONCLUSION

Barbed sutures closure of long wounds is faster and produces a better long-term aesthetic outcome than smooth sutures.

Über die Berechnung von Franck-Condon-Integralen

A new method of approach is proposed for the problem of electronic transitions accompanied by the excitation of molecular or crystal vibrations. The Hamiltonian of the normal vibrations is expressed in terms of the so-called creation and annihilation operators, and the change in the equilibrium nuclear distances and vibrational frequencies are represented by transformations which are also expressed in terms of these operators. Calculations are made for some typical cases.

Perception and Haptic Rendering of Friction Moments

This paper considers moments due to friction forces on the human fingertip. A computational technique called the friction moment arc method is presented. The method computes the static and/or dynamic friction moment independent of a friction force calculation. In addition, a new finger holder to display friction moment is presented. This device incorporates a small brushless motor and disk, and connects the human's finger to an interface finger of the five-fingered haptic interface robot HIRO II. Subjects' perception of friction moment while wearing the finger holder, as well as perceptions during object manipulation in a virtual reality environment, were evaluated experimentally.

Development of a micro-planar amperometric bile acid biosensor for urinalysis

The determination of bile acid concentration in urine is useful for the screening and diagnosis of various hepatobiliary diseases. Currently, there is no concise method to determine bile acid concentration in urine. This study describes a bile acid biosensor fabricated by electrochemical technique for urinalysis. The micro-planar electrodes employed for the study consisted of a working electrode (platinum), a counter electrode (platinum) and a reference electrode (silver/silver chloride (Ag/AgCl)). The sensor chip was coated with Nafion using a spin-coater in order to both eliminate many interference species in urine and achieve long-term stability of the reference electrode. Nafion coating allowed the sensor chip to prevent the electrode reaction from interference species in urine, because it is charged negative strongly (Nafion contains sulfonic acid group). Three enzymes (bile acid sulfate sulfatase: BSS, beta-hydroxysteroid dehydrogenase: beta-HSD, and NADH oxidase: NHO) were immobilized by glutaraldehyde (GA: cross-linker) onto the sensor chip, because the immobilization of enzymes by GA is simple and commonly carried out. The sensor chip was able to detect bile acid in buffer solution. The optimum enzyme ratio immobilized onto the sensor chip was BSS:beta-HSD:NHO=4:4:20 U/1 chip. There was a relationship between the concentration of bile acid and the response current value. The dynamic range of the sensor chip was 2-100 microM for bile acid. Additionally, bile acid in the urine specimen could be detected using this bile acid biosensor. We present a simple and rapid bile acid biosensor with high sensitivity and high reproducibility.

Proprotein convertase PACE4 is down-regulated by the basic helix-loop-helix transcription factor hASH-1 and MASH-1

PACE4 is a mammalian subtilisin-like proprotein convertase that activates transforming growth factor (TGF)-beta-related proteins such as bone morphogenetic protein 2 (BMP2), BMP4 and Nodal and exhibits a dynamic expression pattern during embryogenesis. We recently determined that the 1 kb 5'-upstream region of the PACE4 gene contains 12 E-box (E1-E12) elements and that an E-box cluster (E4-E9) acts as a negative regulator [Tsuji, Yoshida, Hasegawa, Bando, Yoshida, Koide, Mori and Matsuda (1999) J. Biochem. (Tokyo) 126, 494-502]. It is known that the mammalian achaete-scute homologue 1 (MASH-1) binds specifically to an E-box (CACCTG) sequence in collaboration with E47, a ubiquitously expressed basic helix-loop-helix (bHLH) factor. To identify the roles of the bHLH factor and E-box elements in regulating PACE4 gene expression in neural development, we analysed the effects of human achaete-scute homologue 1 (hASH-1) on PACE4 gene expression with various neuroblastoma cell lines. The expressions of PACE4 and hASH-1 are correlated inversely in these cell lines. The overexpression of hASH-1 or MASH-1 causes a marked decrease in endogenous PACE4 gene expression but has no effect on the expression of other subtilisin-like proprotein convertases such as furin, PC5/6 and PC7/8. In contrast, other neural bHLH factors (MATH-1, MATH-2, neurogenin 1, neurogenin 2, neurogenin 3 and E47) did not affect PACE4 gene expression. Furthermore, an E-box cluster was a negative regulatory element for the promoter activity in NBL-S cells expressing hASH-1 at high level as determined by a luciferase assay. Binding of hASH-1 to the E-box cluster was confirmed by gel mobility-shift assay. In the present study we identified the PACE4 gene as one of the targets of hASH-1, which is a key factor in the initiation of neural differentiation. These results suggest that the alteration of PACE4 gene expression by hASH-1 causes rapid changes in the biological activities of TGF-beta-related proteins via post-translational modification of these proteins.

Comparison of remnant-like lipoprotein particles in postmenopausal women with and without coronary artery disease and in men with coronary artery disease

It is known that hypertriglyceridemia is a risk factor of coronary artery disease (CAD) in postmenopausal women. This study prospectively examined whether remnant lipoprotein, an atherogenic triglyceride-rich lipoprotein, may have a significant risk and prognostic values in postmenopausal women with angiographically verified CAD. Remnant-like lipoprotein particles cholesterol (RLP cholesterol) levels in fasting serum were measured in 134 consecutive postmenopausal women with (n = 56) or without (n = 78) CAD by an immunoseparation method. The women with CAD were followed for < or =24 months until occurrence of the following clinical coronary events: readmission or coronary revascularization due to recurrent or refractory angina pectoris, nonfatal myocardial infarction, and cardiac death. Multivariate logistic regression analysis showed that high RLP cholesterol levels (>5.7 mg/dl cholesterol; 90th percentile of the distribution of RLP cholesterol levels in controls) were a significant risk factor for the presence of CAD independent of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, and other traditional risk factors. Kaplan-Meier analysis demonstrated that women with CAD and higher RLP cholesterol levels had a significantly higher probability of developing coronary events (p <0.001). In multivariate Cox hazard analysis, high RLP cholesterol levels as well as diabetes and hypercholesterolemia were a significant predictor of future coronary events independent of other risk factors in women with CAD (odds ratio 9.7, 95% confidence intervals 1.3 to 20.3, p = 0.02). In conclusion, increased levels of RLP cholesterol are a significant and independent risk factor of CAD and predict future coronary events in postmenopausal women with CAD.

The roles of turn formation and cross-strand interactions in fibrillization of peptides derived from the OspA single-layer beta-sheet

We previously demonstrated that a beta-hairpin peptide, termed BH(9-10), derived from a single-layer beta-sheet of Borrelia OspA protein, formed a native-like beta-turn in trifluoroethanol (TFE) solution, and it assembled into amyloid-like fibrils at higher TFE concentrations. This peptide is highly charged, and fibrillization of such a hydrophilic peptide is quite unusual. In this study, we designed a circularly permutated peptide of BH(9-10), termed BH(10-9). When folded into their respective beta-hairpin structures found in OspA, these peptides would have identical cross-strand interactions but different turns connecting the strands. NMR study revealed that BH(10-9) had little propensity to form a turn structure both in aqueous and TFE solutions. At higher TFE concentration, BH(10-9) precipitated with a concomitant alpha-to-beta conformational conversion, in a similar manner to the BH(9-10) fibrillization. However, the BH(10-9) precipitates were nonfibrillar aggregation. The precipitation kinetics of BH(10-9) was exponential, consistent with a first-order molecular assembly reaction, while the fibrillization of BH(9-10) showed sigmoidal kinetics, indicative of a two-step reaction consisting of nucleation and molecular assembly. The correlation between native-like turn formation and fibrillization of our peptide system strongly suggests that BH(9-10) adopts a native-like beta-hairpin conformation in the fibrils. Remarkably, seeding with the preformed BH(10-9) precipitates changed the two-step BH(9-10) fibrillization to a one-step molecular assembly reaction, and disrupted the BH(9-10) fibril structure, indicating interactions between the BH(10-9) aggregates and the BH(9-10) peptide. Our results suggest that, in these peptides, cross-strand interactions are the driving force for molecular assembly, and turn formation limits modes of peptide assembly.

An inferior mesenteric-caval shunt via the internal iliac vein with portosystemic encephalopathy

We report here a case of an unusual extrahepatic portosystemic venous shunt in a 37-year-old woman without liver cirrhosis or portal hypertension, who developed portal systemic encephalopathy. Angiography demonstrated an inferior mesenteric-caval shunt characterized by the presence of direct communication of the inferior mesenteric vein with the left internal iliac vein. After the treatment with percutaneous transcatheter embolization of the shunt via a femoral vein approach using coils, she had no episode of portal systemic encephalopathy.

Stabilization of a fibronectin type III domain by the removal of unfavorable electrostatic interactions on the protein surface

It is generally considered that electrostatic interactions on the protein surface, such as ion pairs, contribute little to protein stability, although they may play important roles in conformational specificity. We found that the tenth fibronectin type III domain of human fibronectin (FNfn10) is more stable at acidic pH than neutral pH, with an apparent midpoint of transition near pH 4. Determination of pK(a)'s for all the side chain carboxyl groups of Asp and Glu residues revealed that Asp 23 and Glu 9 have an upshifted pK(a). These residues and Asp 7 form a negatively charged patch on the surface of FNfn10, with Asp 7 centrally located between Asp 23 and Glu 9, suggesting repulsive electrostatic interactions among these residues at neutral pH. Mutant proteins, D7N and D7K, in which Asp 7 was replaced with Asn and Lys, respectively, exhibited a modest but significant increase in stability at neutral pH, compared to the wild type, and they no longer showed pH dependence of stability. The pK(a)'s of Asp 23 and Glu 9 in these mutant proteins shifted closer to their respective unperturbed values, indicating that the unfavorable electrostatic interactions have been reduced in the mutant proteins. Interestingly, the wild-type and mutant proteins were all stabilized to a similar degree by the addition of 1 M sodium chloride at both neutral and acidic pH, suggesting that the repulsive interactions between the carboxyl groups cannot be effectively shielded by 1 M sodium chloride. These results indicate that repulsive interactions between like charges on the protein surface can destabilize a protein, and protein stability can be significantly improved by relieving these interactions.

Preventing estrogen receptor action with dimer-interface peptides

The human estrogen receptor-alpha (hER) is a ligand-activated transcription factor that functions as a homodimer. We sought to further understand the molecular processes involved in dimerization, and to develop a reagent that may function as an antiestrogen independent of the ligand binding site. To this end, we designed a 16-residue 'dimer-interface' oligopeptide derived from the helical region of the hER which is directly involved in dimerization. This peptide, termed the I-box peptide, has a high helical propensity in aqueous solution. The I-box peptide blocks hER action by causing aggregation and precipitation of both the ligand-bound and apo-hER. This effect is dependent on the helical nature of the peptide. A single Ile to Pro mutation in the helical region of the I-box peptide significantly reduces the helical content and abolishes the precipitation activity. Furthermore, the peptide activity appears to be specific for the hER. The I-box peptide does not significantly affect other proteins or steroid receptors tested. A homologous peptide derived from the nuclear receptor RXRalpha dimer interface, and a LXXLL-containing peptide from the coactivator TIF2 have no detectable in vitro effect on hER function or solubility. Our data suggest that rationally designed molecules capable of affecting steroid receptor quaternary structures may be potential avenues for the development of specific inhibitors of this class of proteins.

An improved method for distinguishing between anisotropic tumbling and chemical exchange in analysis of 15N relaxation parameters

Although an accurate description of global tumbling of a protein is essential for correct analysis of internal motions. proper distinction between the effects of anisotropic rotational diffusion and conformational exchange has remained a challenge. We present a novel two-part filtering procedure designed specifically to distinguish between the effects of anisotropy and conformational exchange. The efficacy of this method is assessed using synthetic data sets. The method is then applied to two proteins of dramatically different size and shape, OspA and SH3. The large size and extreme anisotropy of OspA provide a challenging case, where conformational exchange is a small perturbation of the effects of anisotropy on transverse relaxation rates. Conversely, in the chicken c-Src SH3 domain, with its small size and nearly spherical shape, anisotropy is a small perturbation of the effects of conformational exchange on transverse relaxation rates. Accurate extraction of the global tumbling parameters for each protein allows optimal characterization of conformational exchange processes, as well as ps-ns time scale motions.

Molecular cloning and expression of a novel klotho-related protein

Klotho protein is a novel beta-glucosidase-like protein produced predominantly in the kidney. The klotho mouse, which genetically lacks klotho gene expression, manifests various systemic phenotypes resembling aging. In the present study we succeeded in isolating a novel human protein structurally related to klotho protein. The protein possesses one beta-glucosidase-like domain and is 42% identical with klotho protein at the amino acid level. Unlike klotho protein, it possesses neither a signal sequence nor a transmembrane domain, suggesting that it is a cytosolic protein, and thus was termed cytosolic beta-glucosidase-like protein-1 (cBGL1). By Northern blot analysis cBGL1 mRNA was expressed most abundantly in the liver, followed by the small intestine, colon, spleen, and kidney. When klotho and cBGL1 gene expression was examined in renal cell carcinoma tissues, both klotho and cBGL1 mRNA levels in tumors were lower than those in nontumor regions, suggesting that renal epithelial cells may lose klotho and cBGL1 gene expression during the course of malignant transformation. In conclusion, we describe the primary structure and gene expression of a novel protein related to klotho protein.

Formation of the single-layer beta-sheet of Borrelia burgdorferi OspA in the absence of the C-terminal capping globular domain

Borrelia outer surface protein A (OspA) contains a unique single-layer beta-sheet that connects N and C-terminal globular domains. This single-layer beta-sheet segment (beta-strands 8-10) is highly stable in solution, although it is exposed to the solvent on both faces of the sheet and thus it does not contain a hydrophobic core. Here, we tested whether interactions with the C-terminal domain are essential for the formation of the single-layer beta-sheet. We characterized the solution structure, dynamics and stability of an OspA fragment corresponding to beta-strands 1-12 (termed OspA[27-163]), which lacks a majority of the C-terminal globular domain. Analyses of NMR chemical shifts and backbone nuclear Overhauser effect (NOE) connectivities showed that OspA[27-163] is folded except the 12th and final beta-strand. (1)H-(15)N heteronuclear NOE measurements and amide H-(2)H exchange revealed that the single-layer beta-sheet in this fragment is more flexible than the corresponding region in full-length OspA. Thermal-denaturation experiments using differential scanning calorimetry and NMR spectroscopy revealed that the N-terminal globular domain in the fragment has a conformational stability similar to that of the same region in the full-length protein, and that the single-layer beta-sheet region also has a modest thermal stability. These results demonstrate that the unique single-layer beta-sheet retains its conformation in the absence of its interactions with the C-terminal domain. This fragment is significantly smaller than the full-length OspA, and thus it is expected to facilitate studies of the folding mechanism of this unusual beta-sheet structure.

Clinicopathological study of mucinous gastric carcinoma

BACKGROUND AND AIMS

Mucinous gastric carcinoma (MUC) is relatively a rare subtype of gastric carcinoma, and there has been considerable controversiy over the prognosis of this type of carcinoma. In this study we tried to analyze the clinicopathological differences between MUC and other types of gastric carcinoma (non-MUC) and determine whether MUC is associated with a worse prognosis than non-MUC.

MATERIAL AND METHODS

We reviewed 645 patients with pathologically confirmed gastric cancer who underwent gastrectomy in our facility during the period from 1975 through 1997. Among them, 20 patients (3.1%) had gastric carcinoma with (MUC), and 625 patients had it without extracellular mucin (non-MUC). In addition, we classified MUC into two groups (well-differentiated type; 7 cases and poorly differentiated type; 9 cases) and analyzed the differences between them.

RESULTS

The MUC tumors were more often located in the lower and the upper third of the stomach (MUC: 55% and 25%, non-mUC: 41% and 18%, respectively). The patients with MUC had more serosal invasion (t3 plus t4; MUC: 45%, non-MUC: 18%), more-invasive carcinoma (Type 3 plus 4; MUC: 60%, non-MUC: 36%) and more lymph-node involvement (MUC: 45%, non-MUC: 38%) than the patients with non-MUC. The patients with MUC were more advanced in stage at the time of diagnosis (Stage III plus IV; MUC: 50%, non-MUC: 26%) and had a higher peritoneal dissemination rate (MUC: 30%, non-MUC: 12%) and a lower curability rate (MUC: 60%, non-MUC: 78%) than the patients with non-MUC. The mean size of tumors in MUC (7.4 cm) was larger than that of non-MUC (5.5 cm). Therefore, the overall 5-year survival rate for MUC patients (33%) was lower than that for non-MUC patients (64%). There were no significant differences between well-differentiated and poorly differentiated subtypes of MUC except for the curability and peritoneal dissemination rates.

CONCLUSIONS

The overall survival rate for patients with MUC was worse than that for patients with non-MUC. The poor prognosis was correlated with more advanced stage at diagnosis and more frequent serosal invasion. These results suggest the need to diagnose patients with MUC in the early stage of cancer and that in the case of the advanced stage, wide excision of the surrounding tissues and aggressive lymph-node dissection will be needed.

Specific cytotoxicity of antibody to YAL-198, a sperm antigen peptide, to murine zygote

Active immunization with the peptide segments rSMP-230 and YAL-198, corresponding to the hydrophilic extracellular domain of two human sperm antigens (rSMP-B and YWK-II, respectively), reduced fertility in female rats by different mechanisms. The anti-rSMP-230 antibody interferes with human and murine fertilization, and the anti-YAL-198 antibody blocks the development of mouse embryos. The authors examined in vitro at which stage the antibodies to rSMP-230 and YAL-198 were cytotoxic to murine embryos up to morula/blastocyst stage. Anti-rSMP-230 antibody was not cytotoxic to any stages. On the other hand, the anti-YAL-198 antibody arrested the growth of embryos at the 2-cell stage but not at more advanced developmental stages. When the anti-YAL-198 antibody was used, spotty staining was observed only on the surfaces of embryos that had arrested at the 2-cell stage. Unstained embryos, however, continued to develop normally. In contrast, the anti-rSMP-230 antibody stained murine sperm but failed to stain murine ova and embryos. The present results suggest that the human sperm components rSMP-B and YWK-II play important roles in sperm-egg interaction and early development of the embryo, respectively.

Transventricular mitral annuloplasty in a patient undergoing partial left ventriculectomy

A 70-year-old male patient with heart failure resulting from dilated cardiomyopathy underwent a partial left ventriculectomy between the papillary muscles and a newly devised transventricular mitral annuloplasty. Intraoperative transesophageal Doppler echocardiography revealed reduced ventricular dimensions and corrected mitral insufficiency with unchanged ventricular filling patterns, allowing prompt recovery despite unchanged myocardial pathology.

Partial left ventriculectomy for patients with ischemic cardiomyopathy

BACKGROUND

Partial left ventriculectomy (PLV) has been performed in patients with dilated cardiomyopathy (DCM), but improved myocardial energetics may make PLV useful also for ischemic cardiomyopathy (ICM) unamenable to conventional treatment.

METHODS

Of 262 patients undergoing PLV, 94 patients with ICM as the underlying pathology were analyzed and compared with 168 patients with DCM.

RESULTS

ICM patients were older (57.3 years vs 50.9 years, p = 0.0001) and heavier (69.7 kg vs 65.9 kg, p = 0.039) than those with DCM, but ventricular end-diastolic and end-systolic dimensions were similar with comparably depressed fractional shortening (16% vs 15%, p = 0.294) and equally severe functional limitation [New York Heart Association (NYHA) Class 3.7 vs 3.6, p = 0.734]. A majority of patients in both groups underwent lateral PLV (76% vs 74%, p = 0.883) with myocardium excised between papillary muscles and simultaneous mitral valvuloplasty (41% vs 74%, p < 0.0001). Because ICM patients required coronary artery bypass grafting (CABG) more frequently (79% vs 0.6%, p < 0.0001), operation was more extensive in terms of bypass time (74 minutes vs 47 minutes, p < 0.0001), percentage requiring cardiac arrest (43% vs 19%, p < 0.0001), and arrest duration (34 minutes vs 28 minutes, p = 0.280), but all had similar resection and postoperative ventricular dimensions. Nonetheless, ICM patients required shorter intensive care unit (ICU) time (4.4 days vs 5.9 days, p = 0.048) and similar postoperative hospital stays, resulting in similar hospital survival rates (69% vs 71%, p = 0.778) and functional capacity in long-term follow-up.

CONCLUSIONS

Results suggest that PLV can be performed in patients with ICM with comparable risks and benefits as in DCM. Relative efficacy of CABG and mitral repair as compared to volume reduction remains to be studied.

Mitral regurgitation after partial left ventriculectomy as the cause of ventricular redilatation

BACKGROUND

It remains unclear whether ventricular redilatation after partial left ventriculectomy (PLV) is due to underlying pathology or to continued volume overload amenable to surgery.

METHODS

Among patients undergoing PLV, 32 had Doppler echocardiography preoperatively, immediately after surgery (< 1 week), early after surgery (1-3 months), and late after surgery (8-14 months). Patients were divided into groups with mitral regurgitation (MR; MR+, n = 16) and without postoperative MR (MR-, n = 16) and were compared for ventricular size, performance, and survival.

RESULTS

After initial surgical reduction, left ventricular dimension on average gradually increased back to the preoperative level in subgroups of patients with valvular disease and cardiomyopathy and in all patients combined. Most patients showed drastically reduced left ventricular dimension early after PLV. In MR+ patients, dimension increased back to the preoperative level within 3 months after surgery, whereas the MR- group maintained reduced dimension throughout the first year in all patients combined and in a subgroup of patients with cardiomyopathy. Occurrence of significant MR after PLV appeared to be related to severity of fibrosis in excised myocardium but not to severity of preexisting MR, etiology, or performance of mitral valvuloplasty.

CONCLUSIONS

Early postoperative MR, residual or new, appeared to play an important role in dictating early hemodynamics and late outcome in patients undergoing PLV. Results suggest an aggressive simultaneous approach to abolish MR. Causative role of myocardial fibrosis remains unclear and needs further study.

Perioperative ventricular arrhythmias in patients undergoing partial left ventriculectomy

BACKGROUND

Although incidence of ventricular arrhythmias after partial left ventriculectomy (PLV) has been reported, there are no studies comparing incidence before and after PLV. Although operative scars may give rise to arrhythmias, improved energetic efficiency after PLV may decrease their incidence.

METHODS

Pre- and postoperative ventricular arrhythmias were monitored by Holter ECG and analyzed in 17 patients undergoing PLV in Curitiba, Brazil.

RESULTS

Although total 24-hour heart beat (THB) increased significantly (p = 0.018), ventricular premature contractions (VPCs) decreased markedly (p = 0.036), excluding one patient dying in low cardiac output (LOS) who had terminal arrhythmias increased multifold. In the remaining 16 patients, VPC pairs were also reduced significantly on the average (p = 0.038). In contrast, ventricular tachycardia (VT; more than three consecutive VPCs) disappeared in five patients, decreased in two patients, and newly occurred in four patients, with five patients showing no change; one of them developed a prolonged VT, successfully reversed by external cardioversion.

CONCLUSIONS

Despite notable significant increase in THB immediately after PLV, PVC and PVC pairs were significantly decreased in contrast to VT, which disappeared in some patients and newly occurred in other patients, remaining constant on the average. Sustained VT occurring in a patient with all other arrhythmias suppressed may suggest a unique electrophysiological substrate, may justify prophylactic use of amiodarone or an implantable cardioverter-defibrillator, and may underscore the importance of further and extended studies.

Partial left ventriculectomy. The First Japanese Registry Report 1999

OBJECTIVE

Partial left ventriculectomy has been performed without standardized inclusion/exclusion criteria. A registry has been established to accumulate experience with this procedure to identify indications, risks and benefits.

METHODS

In response to a mailed inquiry, 90 cases were voluntarily registered from 28 Japanese institutions.

RESULTS

Males (n = 67, 74.4%) predominated, and 29 (32.2%) patients were over 60 years old. The underlying cardiac pathologies included dilated cardiomyopathy (n = 75, 83.3%), valvular disease (n = 8, 8.9%), the dilated phase of hypertrophic cardiomyopathy (n = 4, 4.5%), and others (n = 3, 3.3%). Gender, age, etiology, papillary muscle excision and absent transplant indication did not significantly affect survival. Poorer preoperative condition, reduced contraction and decompensation necessitating emergency operation were each associated with a significantly higher risk. Hospitals performing less than 5 cases had poorer results than more experienced institutions (p = .0019), which showed a tendency towards improved survival in the second half of their experience (p = .096). Hospital mortality (n = 29, 32.6%) and late death (n = 10, 11.2%) were mainly from ventricular failure with few sudden deaths over a period of 63.6 patient years follow-up. Late mortality was equally distributed in the first year and leveled off with significantly improved cardiac functional class in survivors.

CONCLUSION

Partial left ventriculectomy was associated with better survival in less symptomatic patients with better contractile reserve undergoing an elective operation preserving the papillary muscles. Avoidance of identified risk factors may allow better patient selection and improved survival in the current environment where rescue transplantation is not readily available. Long-term follow-up is warranted with more registry data.

Crystal structure of outer surface protein C (OspC) from the Lyme disease spirochete, Borrelia burgdorferi

Outer surface protein C (OspC) is a major antigen on the surface of the Lyme disease spirochete, Borrelia burgdorferi, when it is being transmitted to humans. Crystal structures of OspC have been determined for strains HB19 and B31 to 1.8 and 2.5 A resolution, respectively. The three-dimensional structure is predominantly helical. This is in contrast to the structure of OspA, a major surface protein mainly present when spirochetes are residing in the midgut of unfed ticks, which is mostly beta-sheet. The surface of OspC that would project away from the spirochete's membrane has a region of strong negative electrostatic potential which may be involved in binding to positively charged host ligands. This feature is present only on OspCs from strains known to cause invasive human disease.

Magnetohydrodynamic production of relativistic jets

A number of astronomical systems have been discovered that generate collimated flows of plasma with velocities close to the speed of light. In all cases, the central object is probably a neutron star or black hole and is either accreting material from other stars or is in the initial violent stages of formation. Supercomputer simulations of the production of relativistic jets have been based on a magnetohydrodynamic model, in which differential rotation in the system creates a magnetic coil that simultaneously expels and pinches some of the infalling material. The model may explain the basic features of observed jets, including their speed and amount of collimation, and some of the details in the behavior and statistics of different jet-producing sources.

Improved left ventricular contraction and energetics in a patient with Chagas' disease undergoing partial left ventriculectomy

A 43-year-old patient with heart failure, precluded from heart transplantation or dynamic cardiomyoplasty because of Chagas' disease cardiomyopathy, mitral regurgitation, and ventricular mural thrombi, underwent mitral valvuloplasty and partial left ventriculectomy (PLV) between the papillary muscles. Intraoperative pressure-volume relationship analyses suggested improvement in left ventricular contraction, energetics, isovolumic relaxation, and mitral valve competency. These improvements allowed prompt, short-term recovery despite unchanged myocardial pathology, which suggests that a surgical approach can alter anatomic-geometric factors and achieve clinical improvement in a dilated failing ventricle.

Partial left ventriculectomy: the 2nd International Registry Report 2000

BACKGROUND

Partial left ventriculectomy (PLV) has been performed without standardized inclusion or exclusion criteria.

METHODS

An international registry of PLV was expanded, updated, and refined to include 287 nonischemic cases voluntarily reported from 48 hospitals in 11 countries.

RESULTS

Gender, age, ventricular dimension, etiology, ethnology, myocardial mass, operative variation, presence or absence of mitral regurgitation, and transplant indication had no effects on event-free survival, which was defined as absence of death or ventricular failure that required a ventricular assist device or listing for transplantation. Preoperative patient conditions, such as duration of symptoms (> 9 vs < 3 years; p = 0.001), New York Heart Association (NYHA) class (Class IV vs < Class IV; p = 0.002), depressed contractility (fractional shortening [FS] < 5% vs > 12%; p = 0.001), and refractory decompensation that required emergency procedure (p < 0.001) were associated with reduced event-free survival. Five or more cases in each hospital led to significantly better outcomes than the initial four cases. Rescue procedures for 14 patients nonsignificantly improved patient survival (2-year survival 52%) over event-free survival (2-year survival 48%; p = 0.49), with improved NYHA class among survivors (3.6 to 1.8; p < 0.001). Outcome was better in 1999 than in all series before 1999 (p = 0.02) most likely due to patient selection, which was refined to avoid known risk factors such as reduced proportion of patients in NYHA Class IV, FS < 5%, and hospitals with experience in 10 or less cases. A combination of these risk factors could have stratified 17 high-risk patients with 0% 1-year survival and 26 low-risk patients with 75% 2-year event-free survival.

CONCLUSION

Avoidance of risk factors appears to improve survival and might help stratify high- or low-risk patients. Although less symptomatic patients with preserved contractility had better results after PLV, change of indication requires prospective randomized comparison with medical therapies or other approaches.