Identification of distinct subgroups in moderately severe rheumatic mitral stenosis using data-driven phenotyping of longitudinal hemodynamic progression

Background

Rheumatic mitral stenosis (MS) is a significant cause of valvular heart disease. Pulmonary artery systolic pressure (PASP) reflects the hemodynamic consequences of MS and is used to determine treatment strategies. However, PASP progression and expected outcomes in patients with moderately severe MS remain unclear.

Purpose

We aimed to examine the impact of progression rate of PASP in moderately severe MS.

Methods

A cohort of 866 consecutive patients with moderately severe rheumatic MS (1.0 cm2.

Results

Data-driven phenotyping identified two distinct trajectories based on PASP progression: a rapid progression group (N=38, 8.7%) and a slow progression group (N=398, 91.3%). Patients in the rapid progression group were older and had more comorbidities than patients in the slow progression group, including diabetes, and atrial fibrillation (all P<0.05). The initial mean diastolic pressure gradient and PASP were higher in the rapid progression group than in the slow progression group (6.2±2.4 mmHg vs. 5.1±2.0 mmHg, P=0.001, and 42.3±13.3 mmHg vs. 33.0±9.2 mmHg, P<0.001, respectively). During a mean follow-up of 7.0±3.0 years, the event-free survival rate was significantly lower in the rapid progression group than in the slow progression group (log-rank P<0.001). Rapid PASP progression was a significant risk factor for composite outcomes even after adjusting for comorbidities (hazard ratio: 3.08, 95% confidence interval (CI): 1.68–5.64, P<0.001). Multivariate regression analysis revealed that PASP>40 mmHg was independently associated with the probability of rapid progression group allocation (odds ratio: 4.95, 95% CI: 2.08–11.99, P<0.001).

Conclusions

Two groups with distinct patterns of PASP progression were identified. Rapid PASP progression was associated with a significantly higher risk of the composite outcomes. The main independent echocardiographic predictor for rapid progression group allocation was initial PASP>40 mmHg.

Funding Acknowledgement

Type of funding sources: Private hospital(s). Main funding source(s): This study was supported by a Severance Hospital Research fund for Clinical excellence (SHRC) (C-2020-0041) and a faculty research grant of Yonsei University College of Medicine (6-2020-0156).

Prognostic value of liver stiffness in patients with tricuspid regurgitation

Background

It has been known that liver stiffness (LS) assessed by transient elastography is associated with right heart dysfunction and the severity of the tricuspid regurgitation. However, the predictive value of LS for adverse outcome in patients with tricuspid regurgitation (TR) is uncertain.

Objectives

The aim of this study was to identify the prognostic value of LS in patients with moderate or greater degree of TR.

Methods

A total of 257 patients with moderate or severe TR who underwent both echocardiography and liver transient elastography were retrospectively analysed. Patients who have congenital heart disease or chronic liver disease including, viral hepatitis, alcoholic liver disease, autoimmune hepatitis, hepatocellular carcinoma were excluded. Severe LS was defined as elevated kilopascal (kPa) ≥11 (High kPa). Primary outcome was defined as the composite of all-cause death and unplanned admission for heart failure.

Results

One hundred forty-one patients had moderate TR and 116 patients had severe TR. One hundred twenty-eight (50%) patients had severe liver stiffness. During a follow-up period (median 637 days, IQR 1317), 116 (45.1%) primary outcomes occurred. In Kaplan-Meier analysis, patients who had severe TR with high kPa showed the worst outcome. Moreover, patients who had high kPa were associated with worse clinical outcome both moderate TR group and severe TR group than patients with low kPa. In multivariate Cox regression analysis, severe liver stiffness was independently associated with primary outcomes (HR=1.66, 95% CI: 1.28–2.16), p<0.001).

Conclusions

LS is independently associated with adverse clinical outcomes in both patients with moderate and severe TR. The degree of liver fibrosis measured by transient elastography may be a useful marker of cardiac hepatopathy related to TR, and this may contribute to predict the prognosis of TR.

Funding Acknowledgement

Type of funding sources: None.

Differential characteristics associated with progression of mitral and aortic regurgitation in patients undergoing kidney transplantation

Background

Heart valve regurgitation is common in patients with end-stage renal disease (ESRD). However, there are no data on the fate of mitral regurgitation (MR) and aortic regurgitation (AR) after kidney transplantation (KT). In this study, we sought to investigate regression or progression rates of MR and AR after KT in patients with ESRD. Moreover, we aimed to explore clinical and echocardiographic factors associated with the progression of MR and AR in patients undergoing KT.

Methods

Among 1,734 patients who underwent KT from 2005 to 2018 at a single tertiary hospital, 674 patients (407 men; mean 48±12 years) who underwent both pre- and post-KT echocardiography were analyzed comprehensively. Pre-KT echocardiography was performed within three months of KT, and post-KT echocardiography was done between 6 months and 24 months after KT. Severities of MR and AR were graded as no/trivial, mild, moderate, and severe according to the current guidelines. Regression was defined if the severity decreased by one or more grades, while progression was defined if the severity increased by one or more grades.

Results

Figure 1 shows the regression or progression of MR and AR after KT. 78 (11%) patients showed MR regression, but 41 (6%) experienced MR progression. 13 (2%) revealed AR regression, while 23 (4%) presented AR progression. In patients with MR progression, there were more cases of receiving a second KT, having mitral annular calcification, and showing lesser reduction of left atrial volume after KT. Patients with AR progression showed a longer hemodialysis duration, persistent hypertension after KT, and aortic root dilatation. Factors related to the progression of MR and AR showed statistically meaningful predictive values in a stepwise manner (Figure 2)

Conclusions

In patients undergoing KT, MR and AR may progress in patients with certain distinct characteristics. Different clinical and echocardiographic characteristics before KT, and reduction of hemodynamic loads after KT determine the progression of MR and AR. Further echocardiographic surveillances after KT are needed in patients with clinical and echocardiographic factors for progression of valve regurgitation.

Funding Acknowledgement

Type of funding sources: None.

Factors determining mitral valve dysfunction in patients who underwent surgical mitral valve replacement with bio-prosthetic valves

Background

There is increasing Interest in bio-prosthetic MVD as recent advances in transcatheter MV interventions, but there is limited data.

Objectives

The aim of this study was to identify the factors determining mitral valve (MV) dysfunction (MVD) in patients who underwent MV replacement with bio-prosthetic valves. Also, we sought to investigate clinical outcomes in patients with bio-prosthetic MVD.

Methods

A total of 233 patients underwent surgical bio-prosthetic MV replacement between June 1996 and May 2015. Finally, 226 patients (mean age 66.9±11.5 years, 74.3% of women) were analyzed, excluding patients who followed-up for less than 5 years and patients whose baseline or follow-up echocardiography could not be analyzed. Clinical, echocardiographic, and laboratory data were collected early after the surgery and during follow-up. MVD was defined as an increase in mean gradient ≥5 mmHg with leaflet motion limitation and/or newly developed MV regurgitation during follow-up. Clinical outcome was defined as a composite of cardiovascular death, redo MV surgery or intervention, and hospitalization for heart failure.

Results

During a median of 102.0 months (interquartile range 72.0 to 132.0 months), 65 patients (28.8%) revealed MVD. 8 (12.3%) patients revealed predominant MV obstruction, and 57 (87.7%) showed predominant MV regurgitation. Factors associated with bio-prosthetic MVD by multivariate regression analysis were young age at operation (hazard ratio 0.97, 95% CI 0.95–0.99, p=0.001), end-stage renal disease (hazard ratio 4.29, 95% CI 1.45–12.71, p=0.007), elevated mean diastolic pressure gradient>5.5 mmHg across the bio-prosthetic MV early after operation (hazard ratio 1.86, 95% CI 0.97–3.74, p=0.063) and anemia after operation (hazard ratio 0.84, 95% CI 0.74–0.95, p=0.007). However, the presence of hypertension, dyslipidemia, or porcine bio-prosthesis was not related to the bio-prosthetic MVD. Kaplan-Meier curves revealed significant differences in event-free survivals for the occurrence of bio-prosthetic MVD according to each factor (Figure 1). Patients with bio-prosthetic MVD showed significantly poor clinical outcomes compared with those without bio-prosthetic MVD (event-free survival 43.1% vs. 91.9%, log-rank p<0.001) during the follow-up.

Conclusions

Young age at operation, end-stage renal disease, elevated mean pressure gradient early after the operation, and anemia after operation were associated with bio-prosthetic MVD in patients who underwent bio-prosthetic MV replacement.

Funding Acknowledgement

Type of funding sources: None.

Strategies for controlling dog-mediated human rabies in Asia: using 'One Health' principles to assess control programmes for rabies

Over 99% of human rabies cases in endemic areas are transmitted by dogs. Without the elimination of dog rabies, it is not easy to reduce human rabies infection. Controlling dog rabies, especially in ownerless or free-roaming dogs, is critical if we are to decrease the rate of human rabies infection. There are several components in a strategy to eliminate dog-mediated rabies in Asia. Each government must make sure that rabies is either a reportable disease or a notifiable disease and enforce the reporting requirements accordingly. They must also focus on organising and operating special rabies control committees that work with relevant agencies under the 'One Health' banner. They should also implement a national rabies control programme that includes mass dog vaccination, laboratory-based surveillance, stable budget allocation, a rapidreporting system, management of dog populations, international cooperation, prevention of animal introductions from other countries, and risk assessment to analyse the programme's weaknesses. As several developed countries have shown, an effective rabies control strategy leads to rabies-free status. In the Republic of Korea, human rabies has not occurred since 2004, and there have not been any confirmed cases of dog rabies or cases of rabies in wild animals, including raccoon dogs, since 2014. The successful implementation of the key strategies used to eliminate rabies in the Republic of Korea will enable other Asian countries to eliminate dog-mediated human rabies.

First Report of Cucumber mosaic virus in Saintpaulia ionantha in Korea

African violet (Saintpaulia ionantha) is an ornamental species of the family Gesneriaceae and is characterized by fleshy leaves and colorful flowers. This popular, exotic ornamental, originally from Kenya and Tanzania, is vegetatively produced from cutting and tissue culture (1). In May 2013, virus-like foliar symptoms, including a mosaic with dark green islands and chlorosis surrounding the veins, were observed on an African violet plant in a greenhouse located in Icheon, Korea. Cucumber mosaic virus (CMV) was identified in the symptomatic plant by serological testing for the presence of CMV coat protein (CP) with a commercial immunostrip kit (Agdia, Elkhart, IN). The presence of CMV was confirmed by serological detection with a commercially available double-antibody sandwich (DAS)-ELISA kit (Agdia). Sap from the serologically positive sample was mechanically inoculated to test plants using 10 mM phosphate buffer (pH 7.0). The virus (named CMV-AV1) caused necrotic local lesions on Chenopodium amaranticolor at 5 days post-inoculation (dpi), while mild to severe mosaic was observed in Nicotiana glutinosa, N. tabacum 'Samsun NN,' Cucurbita pepo 'Super-Top,' Physalis angulate, and Solanum lycopersicum 'Unicorn' 10 to 14 dpi. Examination of the inoculated plant leaves by DAS-ELISA and electron microscopy (leaf dips) showed positive reactions to CMV and the presence of spherical virions ∼28 nm in diameter, respectively. To verify whether CMV-AV1 is the cause of disease symptoms observed in African violet, virus-free African violet (10 plants) was mechanically inoculated by sap from local lesions on C. amaranticolor inoculated with CMV-AV1. At 8 weeks after inoculation, all plants produced systemic mosaic and chlorosis surrounding veins, resulting in strong DAS-ELISA reactions for CMV, whereas mock-inoculated African violet plants remained symptomless and virus-free. The presence of CMV-AV1 in all naturally infected and mechanically inoculated plants was further verified by reverse transcription (RT)-PCR. Total RNAs were extracted with the RNeasy Plant Mini Kit (Qiagen, Hilden, Germany), according to the manufacturer's instructions. RT-PCR was carried out with the One-Step RT-PCR Kit (Invitrogen, Carlsbad, CA) using a pair of primers, CPTALL3 and CPTALL5 (2), amplifying the entire CP gene and part of an intergenic region and 3'-noncoding region of CMV RNA3. RT-PCR products (960 bp) were obtained from all naturally infected and mechanically inoculated plants as well as from positive control (viral RNAs from virions), but not from healthy tissues. The amplified RT-PCR products were purified with QIAquick PCR Purification Kit (Qiagen) and sequenced using BigDye Termination kit (Applied Biosystems, Foster City, CA). Multiple alignment of the CMV-AV1 CP sequence (Accession No. AB842275) with CP sequences of other CMV isolates using MEGA5 software revealed that 91.8 to 99.0% and 71.0 to 73.0% identities to those of CMV subgroup I and subgroup II, respectively. These results provide additional confirmation of CMV-AV1 infection. CMV may pose a major threat for production of African violet since the farming of African violet plants is performed using the vegetative propagation of the African violet leaves in Korea. In particular, mosaic and chlorosis symptoms in African violet cause damage to ornamental quality of African violet. To our knowledge, this is the first report of CMV infection of African violet in the world. References: (1) S. T. Baatvik. Fragm. Flor. Geobot. Suppl. 2:97, 1993. (2) S. K. Choi et al. J. Virol. Methods 83:67, 1999.

First Report of Cherry necrotic rusty mottle virus Infecting Sweet Cherry Trees in Korea

Cherry necrotic rusty mottle virus (CNRMV), an unassigned member in the family Betaflexiviridae, has been reported in sweet cherry in North America, Europe, New Zealand, Japan, China, and Chile. The virus causes brown, angular necrotic spots, shot holes on the leaves, gum blisters, and necrosis of the bark in several cultivars (1). During the 2012 growing season, 154 sweet cherry trees were tested for the presence of CNRMV by RT-PCR. Samples were randomly collected from 11 orchards located in Gyeonggi and Gyeongsang provinces in Korea. RNA was extracted from leaves using the NucliSENS easyMAG system (bioMérieux, Boxtel, The Netherlands). The primer pair CGRMV1/2 (2) was used to amplify the coat protein region of CNRMV. Although none of the collected samples showed any notable symptoms, CNRMV PCR products of the expected size (949 bp) were obtained from three sweet cherry samples from one orchard in Gyeonggi province. The PCR products were cloned into a pGEM-T easy vector (Promega, Madison, WI) and sequenced. BLAST analyses of the three Korean sequences obtained (GenBank Accession Nos. AB822635, AB822636, and AB822637) showed 97% nucleotide sequence identity with a flowering cherry isolate from Japan (EU188439), and shared 98.8 to 99.6% nucleotide and 99.6 to 100% amino acid similarities to each other. The CNRMV positive samples were also tested for Apple chlorotic leaf spot virus (ACLSV), Cherry mottle leaf virus (CMLV), Cherry rasp leaf virus (CRLV), Cherry leafroll virus (CLRV), Cherry virus A (CVA), Little cherry virus 1 (LChV-1), Prune dwarf virus (PDV), and Prunus necrotic ringspot virus (PNRSV) by RT-PCR. One of the three CNRMV-positive samples was also infected with CVA. To confirm CNRMV infection by wood indexing, Prunus serrulata cv. Kwanzan plants were graft-inoculated with chip buds from the CNRMV-positive sweet cherry trees. At 3 to 4 weeks post-inoculation, the Kwanzan plants showed quick decline with leaves wilting and dying; CNRMV infection of the indicators was confirmed by RT-PCR. To our knowledge, this is the first report of CNRMV infection of sweet cherry trees in Korea. Screening for CNRMV in propagation nurseries should minimize spread of this virus within Korea. References: (1) R. Li and R. Mock. Arch. Virol. 153:973, 2008. (2) R. Li and R. Mock. J. Virol. Methods 129:162, 2005.

Bovine spongiform encephalopathy surveillance in the Republic of Korea

National surveillance for bovine spongiform encephalopathy (BSE) began in the Republic of Korea (ROK) in 1996. Surveillance programmes changed overtime to comply with the guidelines of the World Organisation for Animal Health (OIE). Bovine spongiform encephalopathy was designated as a notifiable disease in 1997. From July 2008, the BSE surveillance programme was intensified to test cattle in designated high-risk populations more effectively. New measures included the compulsory testing of all non-ambulatory cattle at abattoirs, and encouraging the testing of all dead cattle examined and recorded under the Mutual Aid Insurance Scheme (fallen stock). In addition, there was a vigorous search for animals suspected of being clinically infected. As a result, a total of 426,919 OIE points were achieved over a period of seven consecutive years to the end of October 2009. This enabled the submission of a successful application to the OIE in 2010 for recognition of the ROK's BSE disease status as being one of controlled risk, in accordance with Chapter 11.5. of the OIE Terrestrial Animal Health Code.

First Report of Blueberry red ringspot virus Infecting Highbush Blueberry in Korea

Blueberry red ringspot virus (BRRSV) of the Soymovirus genus in the family Caulimovididae causes red ringspot diseases in highbush blueberry (Vaccinium corymbosum L.) on leaves, stems, and fruits. The virus has been identified in the United States, Japan, Czech Republic, Slovenia, and Poland (1). In July 2010, highbush blueberry with red ringspots on leaves and circular blotches on ripening fruits was found in one plant of cv. Duke in Pyeongtaek, Korea. The symptoms were similar to red ringspot disease caused by BRRSV (3), although stems did not show any characteristic symptoms. Red ringspots on the upper surface of leaves were the most visible symptom and became more prominent as leaves matured in August through October. Leaves of the symptomatic plant were collected and tested for BRRSV infection by PCR, and were also embedded for electron microscopy. DNA was extracted from leaves using DNeasy Plant Mini Kit (Qiagen, Valencia, CA) according to the manufacturer's instructions. Primer pairs BR1512F/BR2377R (5'-ACAGGACGATTAGAAGATGG-3'/5'-CCTTTAGGGCAATATTTCTG-3', amplifying a fragment of the coat protein region with an expected size of 865 bp) and BR2961F/BR3726R (5'-ACCGATACATCACAGTTCAC-3'/5'-TGGTTGTGATAAGATGATTCC-3', amplifying a fragment of the reverse transcriptase region with an expected size of 766 bp) were used to amplify the indicated region of BRRV in PCR. Primers were designed on the basis of the BRRSV isolate from New Jersey (GenBank Accession No. AF404509). DNA fragments of the expected sizes were obtained from the symptomatic plant, while no amplification products were obtained from highbush blueberry without symptoms. The PCR products were cloned into pGEM-T easy vector (Promega, Madison, WI) and sequenced. BLAST analyses of obtained fragments revealed 91 to 98% nucleotide sequence identity with the coat protein gene (GenBank Accession No. JQ706341) and 96 to 98% nucleotide sequence identity with the reverse transcriptase gene (GenBank Accession No. JQ706340) of known BRRV isolates. Electron microscopy of thin sections revealed particles approximately 50 nm diameter within electron-dense inclusion bodies, characteristic of BRRSV (2) To our knowledge, this is the first report of BRRSV infection of highbush blueberry in Korea. Highbush blueberries are usually propagated by cutting, so BRRSV suspicious plants should be tested with PCR before they are propagated. References: (1) E. Kalinowska et al. Virus Genes. DOI 10.1007/s11262-011-0679-4, 2011. (2) K. S. Kim et al. Phytopathology 71:673, 1981. (3) M. Isogai et al. J. Gen. Plant Pathol. 75:140, 2009.

Gigacycle fatigue behavior by ultrasonic nanocrystalline surface modification

Nanocrystalline surface layer up to 84 microm in thick is produced on a specimen made of Al6061-T6 alloy by means of surface treatment called ultrasonic nanocrystalline surface modification (UNSM) technique. The refined grain size is produced in the top-layer and it is increased with increasing depth from the top surface. Vickers microhardness measurement for each nanocrystalline surface layer is performed and measurement results showed that the microhardness is increased from 116 HV up to 150 HV, respectively. In this study, fatigue behavior of Al6061-T6 alloy was studied up to 10(7)-10(9) cycles by using a newly developed ultrasonic fatigue testing (UFT) rig. The fatigue results of the UNSM-treated Al6061-T6 alloy specimens were compared with those of the untreated specimens. The microstructure of the untreated and UNSM-treated specimens was characterized by means of scanning electron microscopey (SEM) and transmission electron microscopey (TEM).

Diagnosis and control measures of the 2010 outbreak of foot-and-mouth disease A type in the Republic of Korea

In January 2010, foot-and-mouth disease (FMD) occurred for the first time in 8 years in Korea. The outbreaks were because of A serotype, different from the O type, which had occurred previously in 2000 and 2002. The FMD outbreaks were identified in seven farms, consisting of six cattle farms where viruses were detected and one deer farm where only FMDV antibody was detected. The seven farms were within 9.3 km of each other. All susceptible animals within 10 km radius of the outbreak farms were placed under movement restrictions for 3-11 weeks. No vaccination took place to facilitate the clinical observation of infected animals and virus detection. After clinical observations and serological tests within the control zones showed no evidence of FMD infection, the movement restrictions were lifted, followed by FMD-free declaration (23 March) at 80 days after the first outbreak on 2 January. This communication describes the outbreak of FMD A serotype, and control measures applied to eradicate the disease in Korea.

Cloning and characterization of microRNAs from porcine skeletal muscle and adipose tissue

MicroRNAs (miRNAs) are an abundant class of small regulatory RNAs that regulate the stability and translation of cognate mRNAs. Although an increasing number of porcine miRNAs has recently been identified, the full repertoire of miRNAs in pig remains to be elucidated. To identify porcine miRNAs potentially involved in myogenesis and adipogenesis, we constructed small RNA cDNA libraries from skeletal muscle and adipose tissue and identified 89 distinct miRNAs that are conserved in pig, of which 15 were new. Expression analysis of all newly identified and selected known porcine miRNAs revealed that some miRNAs were enriched in a tissue-specific manner, whereas others were expressed ubiquitously in the porcine tissues examined. Our results expand the number of known porcine miRNAs and provide useful information for further investigating the biological functions of miRNAs associated with growth and development of skeletal muscle or adipose tissue in pig.

Silencing by small RNAs is linked to endosomal trafficking

Small RNAs direct RNA-induced silencing complexes (RISCs) to regulate stability and translation of mRNAs. RISCs associated with target mRNAs often accumulate in discrete cytoplasmic foci known as GW-bodies. However, RISC proteins can associate with membrane compartments such as the Golgi and endoplasmic reticulum. Here, we show that GW-bodies are associated with late endosomes (multivesicular bodies, MVBs). Blocking the maturation of MVBs into lysosomes by loss of the tethering factor HPS4 (ref. 5) enhances short interfering RNA (siRNA)- and micro RNA (miRNA)-mediated silencing in Drosophila melanogaster and humans. It also triggers over-accumulation of GW-bodies. Blocking MVB formation by ESCRT (endosomal sorting complex required for transport) depletion results in impaired miRNA silencing and loss of GW-bodies. These results indicate that active RISCs are physically and functionally coupled to MVBs. We further show that MVBs promote the competence of RISCs in loading small RNAs. We suggest that the recycling of RISCs is promoted by MVBs, resulting in RISCs more effectively engaging with small RNA effectors and possibly target RNAs. It may provide a means to enhance the dynamics of RNA silencing in the cytoplasm.

Identification and characterization of new microRNAs from pig

MicroRNAs (miRNAs) are small regulatory RNAs that direct the posttranscriptional repression of cognate messenger RNAs. Despite increasing evidence for diverse roles of miRNAs in biological processes, little is known about miRNAs in pig. We describe the first experimental identification of porcine miRNAs by sequence analysis of a cDNA library of small RNAs from porcine fibroblast cells. We identified 25 distinct porcine miRNAs, of which 19 are previously unreported, and define 14 new miRNA families in pig. Most of the cloned miRNAs are expressed ubiquitously in all porcine tissues examined, whereas some miRNAs are expressed preferentially in specific tissues. Our results enrich the porcine miRNA database and provide useful information for investigating biological functions of miRNAs in pig.

Pathogenic characteristics of the Korean 2002 isolate of foot-and-mouth disease virus serotype O in pigs and cattle

Experimental infection of susceptible cattle and pigs showed that the O/SKR/AS/2002 pig strain of foot-and-mouth disease virus (FMDV) causes an infection that is highly virulent and contagious in pigs but very limited in cattle. Pigs directly inoculated with, or exposed to swine infected with, strain O/SKR/AS/2002 showed typical clinical signs, including gross vesicular lesions in mouth and pedal sites. In addition, FMDV was isolated from, and FMDV genomic RNA was detected in, blood, serum, nasal swabs and oesophageal-pharyngeal (OP) fluid early in the course of infection. Antibodies against the non-structural protein (NSP) 3ABC were detected in both directly inoculated and contact pigs, indicating active virus replication. In contrast, the disease in cattle was atypical. After inoculation, lesions were confined to the infection site. A transient viraemia occurred 1 and 2 days after inoculation, and this was followed by the production of antibodies to NSP 3ABC, indicating subclinical infection. No clinical disease was seen, and no antibodies to NSP 3ABC were present in contact cattle. Additionally, no virus or viral nucleic acid was detected in blood, nasal swab and OP fluid samples from contact cattle. Thus, the virus appeared not to be transmitted from infected cattle to contact cattle. In its behaviour in pigs and cattle, strain O/SKR/AS/2002 resembled the porcinophilic FMDV strain of Cathay origin, O/TAW/97. However, the latter, unlike O/SKR/AS/2002, has reduced ability to grow in bovine-derived cells. The porcinophilic character of O/TAW/97 has been attributed to a deletion in the 3A coding region of the viral genome. However, O/SKR/AS/2002 has an intact 3A coding region.

Catalytically inactive lipoprotein lipase expression in muscle of transgenic mice increases very low density lipoprotein uptake: direct evidence that lipoprotein lipase bridging occurs in vivo

Lipoprotein lipase (LPL) is the central enzyme in plasma triglyceride hydrolysis. In vitro studies have shown that LPL also can enhance lipoprotein uptake into cells via pathways that are independent of catalytic activity but require LPL as a molecular bridge between lipoproteins and proteoglycans or receptors. To investigate whether this bridging function occurs in vivo, two transgenic mouse lines were established expressing a muscle creatine kinase promoter-driven human LPL (hLPL) minigene mutated in the catalytic triad (Asp156 to Asn). Mutated hLPL was expressed only in muscle and led to 3,100 and 3,500 ng/ml homodimeric hLPL protein in post-heparin plasma but no hLPL catalytic activity. Less than 5 ng/ml hLPL was found in preheparin plasma, indicating that proteoglycan binding of mutated LPL was not impaired. Expression of inactive LPL did not rescue LPL knock-out mice from neonatal death. On the wild-type (LPL2) background, inactive LPL decreased very low density lipoprotein (VLDL)-triglycerides. On the heterozygote LPL knock-out background (LPL1) background, plasma triglyceride levels were lowered 22 and 33% in the two transgenic lines. After injection of radiolabeled VLDL, increased muscle uptake was observed for triglyceride-derived fatty acids (LPL2, 1.7x; LPL1, 1.8x), core cholesteryl ether (LPL2, 2.3x; LPL1, 2.7x), and apolipoprotein (LPL1, 1.8x; significantly less than cholesteryl ether). Skeletal muscle from transgenic lines had a mitochondriopathy with glycogen accumulation similar to mice expressing active hLPL in muscle. In conclusion, it appears that inactive LPL can act in vivo to mediate VLDL removal from plasma and uptake into tissues in which it is expressed.

Discovery of MC-02,331, a new cephalosporin exhibiting potent activity against methicillin-resistant Staphylococcus aureus

A systematic approach toward building activity against methicillin-resistant staphylococci into the cephalosporin class of beta-lactam antibiotics is described. Initial work focused on finding the optimal linkage between the cephem nucleus and a biphenyl pharmacophore, which established that a thio linkage afforded potent activity in vitro. Efforts to optimize this activity by altering substitution on the pharmacophore afforded iodophenylthio analog MC-02,002, which although highly potent against MRSA, was also highly bound to serum proteins. Further work to decrease serum protein binding showed that replacement of the iodo substituent by the positively-charged isothiouronium group afforded potent activity and reduced serum binding, but insufficient aqueous solubility. Solubility was enhanced by incorporation of a second positively-charged group into the 7-acyl substituent. Such derivatives (MC-02,171 and MC-02,306) lacked sufficient stability to staphylococcal beta-lactamase enzymes. The second positive charge was incorporated into the cephem 3-substituent in order to utilize the beta-lactamase-stable aminothiazolyl(oximino)acetyl class of 7-substituents. These efforts culminated with the discovery of bis(isothiouroniummethyl)phenylthio analog MC-02,331, whose profile is acceptable with respect to potency against MRSA, serum binding, aqueous solubility, and beta-lactamase stability.

Development of a Web-based CAI program for maternity nursing practice

This quasi-experimental study was conducted to explore what kind of impact a Web-based educational program can have on nursing students and how nursing students react to this educational program. A Web-based computer assisted instruction for maternity nursing practice was developed by researchers using Instruction System Design model and serviced for nursing students on the WWW. To study educational effect of this program on nursing students 30 senior students at a school of nursing were selected. They were assigned into experimental and control groups based on their maternity nursing practice schedule. The effect of the Web-based CAI was measured using Achievement score, attitude toward learning experience and attitude toward computer and Internet, and compared between two groups. There were significant differences between two groups in achievement and attitude score. And students in the experimental group showed positive response to the Web-based CAI program. These results suggest that Web-based CAI is useful as a new teaching tool for maternity nursing practice as well as other nursing courses. Comments on program improvement and operational issues were collected from students. These will be used for program improvement in future.