Targeting the Apoa1 locus for liver-directed gene therapy

Clinical application of somatic genome editing requires therapeutics that are generalizable to a broad range of patients. Targeted insertion of promoterless transgenes can ensure that edits are permanent and broadly applicable while minimizing risks of off-target integration. In the liver, the Albumin (Alb) locus is currently the only well-characterized site for promoterless transgene insertion. Here, we target the Apoa1 locus with adeno-associated viral (AAV) delivery of CRISPR-Cas9 and achieve rates of 6% to 16% of targeted hepatocytes, with no evidence of toxicity. We further show that the endogenous Apoa1 promoter can drive robust and sustained expression of therapeutic proteins, such as apolipoprotein E (APOE), dramatically reducing plasma lipids in a model of hypercholesterolemia. Finally, we demonstrate that Apoa1-targeted fumarylacetoacetate hydrolase (FAH) can correct and rescue the severe metabolic liver disease hereditary tyrosinemia type I. In summary, we identify and validate Apoa1 as a novel integration site that supports durable transgene expression in the liver for gene therapy applications.

Intervertebral disc degeneration and regeneration: a motion segment perspective

Back and neck pain have become primary reasons for disability and healthcare spending globally. While the causes of back pain are multifactorial, intervertebral disc degeneration is frequently cited as a primary source of pain. The annulus fibrosus (AF) and nucleus pulposus (NP) subcomponents of the disc are common targets for regenerative therapeutics. However, disc degeneration is also associated with degenerative changes to adjacent spinal tissues, and successful regenerative therapies will likely need to consider and address the pathology of adjacent spinal structures beyond solely the disc subcomponents. This review summarises the current state of knowledge in the field regarding associations between back pain, disc degeneration, and degeneration of the cartilaginous and bony endplates, the AF-vertebral body interface, the facet joints and spinal muscles, in addition to a discussion of regenerative strategies for treating pain and degeneration from a whole motion segment perspective.

HDAC Inhibition Reverses Preexisting Diastolic Dysfunction and Blocks Covert Extracellular Matrix Remodeling

BACKGROUND

Diastolic dysfunction (DD) is associated with the development of heart failure and contributes to the pathogenesis of other cardiac maladies, including atrial fibrillation. Inhibition of histone deacetylases (HDACs) has been shown to prevent DD by enhancing myofibril relaxation. We addressed the therapeutic potential of HDAC inhibition in a model of established DD with preserved ejection fraction.

METHODS

Four weeks after uninephrectomy and implantation with deoxycorticosterone acetate pellets, when DD was clearly evident, 1 cohort of mice was administered the clinical-stage HDAC inhibitor ITF2357/Givinostat. Echocardiography, blood pressure measurements, and end point invasive hemodynamic analyses were performed. Myofibril mechanics and intact cardiomyocyte relaxation were assessed ex vivo. Cardiac fibrosis was evaluated by picrosirius red staining and second harmonic generation microscopy of left ventricle (LV) sections, RNA sequencing of LV mRNA, mass spectrometry-based evaluation of decellularized LV biopsies, and atomic force microscopy determination of LV stiffness. Mechanistic studies were performed with primary rat and human cardiac fibroblasts.

RESULTS

HDAC inhibition normalized DD without lowering blood pressure in this model of systemic hypertension. In contrast to previous models, myofibril relaxation was unimpaired in uninephrectomy/deoxycorticosterone acetate mice. Furthermore, cardiac fibrosis was not evident in any mouse cohort on the basis of picrosirius red staining or second harmonic generation microscopy. However, mass spectrometry revealed induction in the expression of >100 extracellular matrix proteins in LVs of uninephrectomy/deoxycorticosterone acetate mice, which correlated with profound tissue stiffening based on atomic force microscopy. ITF2357/Givinostat treatment blocked extracellular matrix expansion and LV stiffening. The HDAC inhibitor was subsequently shown to suppress cardiac fibroblast activation, at least in part, by blunting recruitment of the profibrotic chromatin reader protein BRD4 (bromodomain-containing protein 4) to key gene regulatory elements.

CONCLUSIONS

These findings demonstrate the potential of HDAC inhibition as a therapeutic intervention to reverse existing DD and establish blockade of extracellular matrix remodeling as a second mechanism by which HDAC inhibitors improve ventricular filling. Our data reveal the existence of pathophysiologically relevant covert or hidden cardiac fibrosis that is below the limit of detection of histochemical stains such as picrosirius red, highlighting the need to evaluate fibrosis of the heart using diverse methodologies.

Impact of the fire ant pesticide AMDRO on loggerhead turtle nest productivity and seafinding orientation

Invasive fire ants prey on a variety of organisms in the southeastern USA, including the pipped eggs and hatchlings within sea turtle nests. The granular fire ant bait AMDRO® (active ingredient hydramethylnon) is currently used at some rookeries to protect nests, but no studies have been conducted to determine if the pesticide negatively impacts the eggs or the hatchlings. We examined the pesticide’s effect on loggerhead (Caretta caretta) nests at Juno Beach, Florida, USA, specifically targeting how exposure affected hatching success, hatchling emergence success, and the ability of the turtles to orient visually from the nest to the sea. Pesticide granules were placed within a 30 cm diameter circle on the sand directly above the nest during the final 5-10 days of incubation, representative of its typical application at nesting beaches. Cornmeal granules in soybean oil and untreated natural nests served as controls. AMDRO had no significant effect on hatching success or emergence success, nor did it result in any deficiencies in hatchling orientation accuracy. However, the pesticide and cornmeal control attracted other predators (Atlantic ghost crabs and avian species), in addition to fire ants, to the nest site, thus revealing the nest’s location and potentially increasing its vulnerability. Consequently, we suggest that its usage may not be beneficial at sites where predators other than ants are especially abundant.

Effectiveness of self-management interventions in young adults with type 1 and 2 diabetes: a systematic review and meta-analysis

AIM

Diabetes in young adulthood has been associated with poor outcomes. Self-management is fundamental to good diabetes care, and self-management interventions have been found to improve outcomes in older adults. We performed a systematic review and meta-analysis to assess the effectiveness of self-management interventions in young adults (aged 15-39 years) with type 1 or type 2 diabetes.

METHODS

We searched five databases and two clinical trial registries from 2003 to February 2019, without language restrictions. We included randomized controlled trials (RCTs) comparing the effectiveness of self-management interventions with usual care or enhanced usual care in young adults. Outcomes of interest included clinical outcomes, psychological health, self-care behaviours, diabetes knowledge and self-efficacy. Pairwise meta-analysis was conducted using a random effects model and quality of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) criteria. We followed Cochrane gold standard systematic review methodology and reported this systematic review according to PRISMA guidelines. The protocol was registered with PROSEPRO (CRD42018110868).

RESULTS

In total, 13 studies (1002 participants) were included. Meta-analysis showed no difference between self-management interventions and controls in post-intervention HbA_1c levels, BMI, depression, diabetes-related distress, overall self-care, diabetes knowledge and self-efficacy. Quality of evidence ranged from very low to moderate due to study limitations, inconsistency and imprecision.

CONCLUSIONS

Current self-management interventions did not improve outcomes in young adults with diabetes. Our findings, which contrast with those from systematic reviews in older adults, highlight the need for the development of more effective interventions for young adults with diabetes.

Attitudes and perception of influenza vaccines among older people in Singapore: A qualitative study

Background

Despite recommendations for influenza vaccination of people aged 65 and above, uptake rate of influenza vaccines remains low.

This study aims to understand barriers and motivators behind older adult’s decision on influenza vaccination.

Methods

Face to face interviews with participants aged 65 and above were conducted and audio recorded in Geylang polyclinic in Singapore. Thematic content analysis was used to organise the data.

Results

15 older adults were interviewed, aged between 66 and 85 years old. 6 were vaccine refusers, 3 defaulters and 6 acceptors.

A perceived lack of vulnerability, fear of side effects, and trivialisation of influenza were common reasons for not taking the vaccine. Encouragement from family and friends, travel and previous positive vaccination experiences were motivators for getting vaccinated. Healthcare workers played a role in influencing many of the participants’ decision-making. Common misconceptions included vaccines considered as necessary only before travel and as a cure rather than prevention. Most participants exhibited ambivalence, giving reasons both for and against vaccine uptake.

Discussion

Most older adults do not perceive influenza as a potentially serious disease nor trust in influenza vaccines’ efficacy. Misconceptions played a significant role in vaccine decline. Novel findings include the importance of the family unit in decision making, prioritization of chronic health problems over vaccination and misconception that vaccines are only needed when travelling out of country. Healthcare workers and family members appear to be important influencers in the decision making of older adults and should be actively engaged in future health promotion initiatives.

Dynamic Chromatin Targeting of BRD4 Stimulates Cardiac Fibroblast Activation

RATIONALE

Small molecule inhibitors of the acetyl-histone binding protein BRD4 have been shown to block cardiac fibrosis in preclinical models of heart failure (HF). However, since the inhibitors target BRD4 ubiquitously, it is unclear whether this chromatin reader protein functions in cell type-specific manner to control pathological myocardial fibrosis. Furthermore, the molecular mechanisms by which BRD4 stimulates the transcriptional program for cardiac fibrosis remain unknown.

OBJECTIVE

We sought to test the hypothesis that BRD4 functions in a cell-autonomous and signal-responsive manner to control activation of cardiac fibroblasts, which are the major extracellular matrix-producing cells of the heart.

METHODS AND RESULTS

RNA-sequencing, mass spectrometry, and cell-based assays employing primary adult rat ventricular fibroblasts demonstrated that BRD4 functions as an effector of TGF-β (transforming growth factor-β) signaling to stimulate conversion of quiescent cardiac fibroblasts into Periostin (Postn)-positive cells that express high levels of extracellular matrix. These findings were confirmed in vivo through whole-transcriptome analysis of cardiac fibroblasts from mice subjected to transverse aortic constriction and treated with the small molecule BRD4 inhibitor, JQ1. Chromatin immunoprecipitation-sequencing revealed that BRD4 undergoes stimulus-dependent, genome-wide redistribution in cardiac fibroblasts, becoming enriched on a subset of enhancers and super-enhancers, and leading to RNA polymerase II activation and expression of downstream target genes. Employing the Sertad4 (SERTA domain-containing protein 4) locus as a prototype, we demonstrate that dynamic chromatin targeting of BRD4 is controlled, in part, by p38 MAPK (mitogen-activated protein kinase) and provide evidence of a critical function for Sertad4 in TGF-β-mediated cardiac fibroblast activation.

CONCLUSIONS

These findings define BRD4 as a central regulator of the pro-fibrotic cardiac fibroblast phenotype, establish a p38-dependent signaling circuit for epigenetic reprogramming in heart failure, and uncover a novel role for Sertad4. The work provides a mechanistic foundation for the development of BRD4 inhibitors as targeted anti-fibrotic therapies for the heart.

Nonpharmacological interventions aimed at modifying health and behavioural outcomes for adults with asthma: a critical review

Evidence suggests that living with asthma is linked with psychological and behavioural factors including self-management and treatment adherence, and therefore, there is a reasonable hypothesis that nonpharmacological treatments may improve health outcomes in people living with this condition. A systematic review of randomized controlled trials (RCTs) of nonpharmacological interventions for adults with asthma was designed. Databases searched included The Cochrane Airways Group Register of trials, CENTRAL and Psychinfo. The literature search was conducted until May 2014. Twenty-three studies met the inclusion criteria and were organized into four groups: relaxation-based therapies (n = 9); mindfulness (n = 1), biofeedback techniques (n = 3); cognitive behavioural therapies (CBT) (n = 5); and multicomponent interventions (n = 5). A variety of outcome measures were used, even when trials belonged to the same grouping, which limited the ability to conduct meaningful meta-analyses. Deficiencies in the current evidence base, notably trial heterogeneity, means that application to clinical practice is limited and clear guidelines regarding the use of nonpharmacological therapies in asthma is limited. Relaxation and CBT, however, appear to have a consistent positive effect on asthma-related quality of life and some psychological outcomes, and lung function (relaxation only). Future trials should be informed by previous work to harmonize the interventions under study and outcome measures used to determine their effectiveness; only then will meaningful meta-analyses inform clinical practice.

Ultrasound-guided selective block of the anterior branch of the obturator nerve for transurethral resection of bladder tumour

Introduction:

Bladder perforation is a serious complication of transurethral resection of bladder tumour (TURBT). One of the risk factors is an “obturator jerk”, caused by stimulation of the obturator nerve, causing powerful adduction of the leg. As almost half of all bladder tumours are located on the lateral wall and 55–100% of resections on the lateral wall can result in obturator jerk; this is not an insignificant risk.

Patients:

We have introduced regional anaesthetic nerve block of the anterior branch of the obturator nerve in patients with known lateral wall tumours undergoing TURBT.

Methods:

This procedure was performed by two consultant anaesthetists in our unit. Patients are positioned supine with the leg slightly abducted and laterally rotated. Ultrasound (US) is used to identify the anterior branch of the adductor longus, brevis and magnus muscles in the medial thigh, 2–3 cm inferior to the inguinal crease. The obturator nerve is situated in the plane between adductor longus and adductor brevis, medial to pectineus. An insulated needle is passed under US guidance and a nerve stimulator is used to elicit a twitch. Levobupivicaine is used to infiltrate the anterior branch of the obturator nerve to achieve motor block of the adductor brevis, adductor longus and gracillis muscles. TURBT is then performed.

Results:

This prospective pilot series includes 18 TURBT procedures. These were performed under spinal anaesthetic ( n=16) or general anaesthetic without muscle relaxant ( n=2). Tumours characteristics were; large flat areas of re-resection ( n=5), flat bladder lesions ( n=1) or exophytic lesions ( n=12). There were no incidences of obturator jerk observed during TURBT (0/18). There were no intra or post-operative complications.

Conclusion:

This simple technique can be easily applied to patients undergoing TURBT. Larger studies are required, but our series supports the use of this technique to reduce obturator jerk, which is an important risk factors for bladder perforation.

An emerging zoonotic clone in the Netherlands provides clues to virulence and zoonotic potential of Streptococcus suis

Streptococcus suis is a zoonotic swine pathogen and a major public health concern in Asia, where it emerged as an important cause of bacterial meningitis in adults. While associated with food-borne transmission in Asia, zoonotic S. suis infections are mainly occupational hazards elsewhere. To identify genomic differences that can explain zoonotic potential, we compared whole genomes of 98 S. suis isolates from human patients and pigs with invasive disease in the Netherlands, and validated our observations with 18 complete and publicly available sequences. Zoonotic isolates have smaller genomes than non-zoonotic isolates, but contain more virulence factors. We identified a zoonotic S. suis clone that diverged from a non-zoonotic clone by means of gene loss, a capsule switch, and acquisition of a two-component signalling system in the late 19th century, when foreign pig breeds were introduced. Our results indicate that zoonotic potential of S. suis results from gene loss, recombination and horizontal gene transfer events.

Measuring asthma-specific quality of life: structured review

Measuring quality of life (QoL) has become an increasingly important dimension of assessing patient well-being and drug efficacy. As there are now several asthma QoL questionnaires to choose from, it is important to appreciate their strengths and weaknesses. To assist in this choice, we have reviewed the existing questionnaires in a structured way. Information relating to the conceptual and measurement model, reliability, validity, interpretability, burden, administration format and translations was extracted from the published literature. The instruments differ in almost all criteria considered, and therefore it cannot be assumed that they measure the same thing. We recommend the selection of questionnaires that are designed only for asthma and that do not assess symptoms as part of QoL. Only two of the questionnaires reviewed fulfill these requirements: the Sydney Asthma QoL Questionnaire (AQLQ-S) and the Living with Asthma Questionnaire (LWAQ). However, for multinational studies, it may be convenient or practical to use questionnaires that have been linguistically validated in many languages (AQLQ-J, SGRQ). It remains unclear which of these questionnaires best reflects patient perceptions of QoL. Our review did not involve patients, so for the time being choosing from existing questionnaires requires a compromise based on the rigor of the development process and the target patient group.

The use of conventional and complementary treatments for knee osteoarthritis in the community

OBJECTIVES

The aim of the survey was to assess the prevalence of clinically diagnosed knee osteoarthritis (OA) in two general practice populations in the Wessex region (practice A: a deprived urban population and practice B: an affluent rural population) and to assess both conventional and complementary therapy use in these two populations.

METHODS

All patients over 55 yr with a clinical diagnosis of knee OA, as identified from the practice computerized records, were sent a questionnaire about their knee pain and their use of conventional and complementary treatments.

RESULTS

A total of 4566 patients over 55 yr were registered in the two practices. Of these, 828 (18.13%) had a clinical diagnosis of knee OA and 240 (29%) patients were asymptomatic at the time of survey. Physiotherapy was under-utilized with only 13.1% of patients having received either hospital- or GP-based physiotherapy. There was a high prevalence of non-steroidal anti-inflammatory drug (NSAID) use, being significantly more in the affluent population (P < 0.05). In the affluent population there were statistically more social class groups 1-3a; statistically more NSAIDs, glucosamine and chondroitin sulphate were also used. The median amount spent on complementary medicine per month was 5.00 UK pounds, with the affluent population spending significantly more (P < 0.05).

CONCLUSIONS

In this population, physiotherapy is an under-utilized treatment for knee OA, in spite of its recommendation as first-line treatment in all guidelines. Complementary medicines and therapies are commonly used, particularly in affluent populations.

The gram-positive tonsillar and nasal flora of piglets before and after weaning

AIMS

To investigate gram-positive nasal and tonsillar microbial flora of piglets before and after weaning.

METHODS AND RESULTS

The nasal and tonsillar gram-positive bacterial flora of 20 non-weaned piglets (2 weeks of age) and 20 weaned piglets (6 weeks of age), obtained from four different piggeries, was quantified by culture and identified by tDNA-PCR. The most widely occurring species from nasal conchae before as well as after weaning in the different piglets investigated were Streptococcus suis and Rothia nasimurium. After weaning a wide variety of Lactobacillus species appeared but in low numbers. In the tonsils, Strep. suis, Strep. dysgalactiae, S. hyicus, S. aureus, Arcanobacterium pyogenes and Actinomyces hyovaginalis were the species isolated from the largest number of pigs before and after weaning. S. aureus and most lactobacilli became more prevalent after weaning. Bacteria not known to be associated with pigs found in the present study included R. nasimurium, Strep. gallolyticus, Pediococcus pentosaceus and some Lactobacillus species.

CONCLUSIONS

Over 30 different gram-positive bacterial species may occur in nasal conchae and tonsils of unweaned piglets at 2 weeks of age and of 6-week-old weaned piglets.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrated that weaning is associated with changes in prevalence of only a small minority of the highly diversified bacterial flora of the nares and tonsils of pigs.

Spatial variation in cartilage T2 of the knee

Technical limitations imposed by resolution and B1 homogeneity have thus far limited quantitative in vivo T2 mapping of cartilage to the patella. The purpose of this study is to develop T2 mapping of the femoral/tibial joint and assess regional variability of cartilage T2 in the knee. Quantitative in vivo T2 mapping of the knee was performed on 15 asymptomatic adults (age, 22-44) using a 3T MR scanner. There is a consistent pattern of spatial variation in cartilage T2 with longer values near the articular surface. The greatest variation occurs in the patella, where T2 increases from 45.3 +/- 2.5 msec at a normalized distance of 0.33-67 +/- 5.5 msec at a distance of 1.0. These results demonstrate feasibility of performing in vivo T2 mapping of femoral tibial cartilage. Except for the superficial 15% where T2 values are lower, the spatial variation in T2 of femoral and tibial cartilage is similar to patellar cartilage.

The major bovine mastitis pathogens have different cell tropisms in cultures of bovine mammary gland cells

We previously showed that Staphylococcus aureus cells adhered mainly to an elongated cell type, present in cultures of bovine mammary gland cells. Moreover, we showed that this adhesion was mediated by binding to fibronectin. The same in vitro model was used here, to study adhesion of other important mastitis pathogens. Like the S. aureus strains, the Streptococcus dysgalactiae strains adhered mainly to elongated cells, which seemed to be mediated by fibronectin binding. In contrast, Streptococcus uberis strains adhered mainly to cubic cells. Since the cubic cells did not express fibronectin and S. uberis cells bound fibronectin less efficiently, the adhesion of S. uberis cells was independent of fibronectin binding. Streptococcus agalactiae strains adhered poorly to both cell types. The specificity and efficiency of adhesion of Escherichia coli strains was strongly strain dependent. None of the S. agalactiae and E. coli strains tested was able to bind fibronectin efficiently. The results suggest that the different mastitis pathogens have different target cell specificities and use different mechanisms to adhere to cells of the bovine mammary gland.

Protection of pigs against challenge with virulent Streptococcus suis serotype 2 strains by a muramidase-released protein and extracellular factor vaccine

The efficacy of a muramidase-released protein (MRP) and extracellular factor (EF) vaccine in preventing infection and disease in pigs challenged either with a homologous or a heterologous Streptococcus suis serotype 2 strain (MRP+EF+) was compared with the efficacy of a vaccine containing formalin-killed bacterin of S. suis serotype 2 (MRP+EF+). The enhancement of the immune response by different adjuvants (a water-in-oil emulsion [WO] and an aluminium hydroxide-based adjuvant [AH]) and their side effects were also studied. The MRP and EF were purified by affinity chromatography. Pigs were vaccinated twice at three weeks and six weeks of age and challenged intravenously with virulent S. suis serotype 2 strains (MRP+EF+) at eight weeks of age. At challenge, the pigs vaccinated with MRP+EF/WO had high anti-MRP and anti-EF titres and were protected as effectively as pigs vaccinated with WO-formulated vaccines with bacterin. Eight of the nine pigs survived the challenge and almost no clinical signs of disease were observed. The titres obtained with the MRP+EF/AH vaccine were low and only two of the five pigs were protected. Pigs vaccinated with either MRP or EF were less well protected; three of the four pigs died after challenge but the clinical signs of disease were significantly less severe than those observed in the placebo-vaccinated pigs. The protective capacity of the bacterin/AH vaccine was very low, and the mortality among these pigs was as high as in the placebo-vaccinated pigs (80 per cent). Postmortem histological examination revealed meningitis, polyserositis and arthritis in the clinically affected pigs. The results demonstrate that a subunit vaccine containing both MRP and EF, formulated with the WO adjuvant, protected pigs against challenge with virulent S. suis type 2 strains.

Sublingual immunotherapy

Recent claims have been made that sublingual immunotherapy (SLIT) may be a viable alternative to injection immunotherapy (SIT). Animal studies show that when allergens are administered topically, they are handled differently, and IgE responses can be reduced. Most published studies of human SLIT have been small but show fairly consistent benefits on symptom scores, with few systemic side effects. Objective measures of allergen reactivity usually do not change. Relatively few subjects have been treated in SLIT trials compared with the numbers that would be required to validate new drug therapies. On the plus side, SLIT appears to work in adults and in children; it offers some logistic advantages and seems to be safe. Giving allergen by mouth rather than by injection should decrease the costs of immunotherapy, but the cumulative dose of allergen used in SLIT has been between 20 to 375 times the dose given in conventional SIT. Further cost-benefit analysis is needed. On the other hand, standard SIT is effective and is supported by better clinical and experimental evidence. The balance sheet for SLIT is improving, but on the current evidence, SLIT requires further evaluation before it could be recommended for use in routine clinical practice.

Selection of virulence-associated determinants of Streptococcus suis serotype 2 by in vivo complementation

Within Streptococcus suis serotype 2, pathogenic, weakly pathogenic, and nonpathogenic strains can be found. We introduced a genomic library of a pathogenic strain into a weakly pathogenic strain. After infection of the library into young piglets pathogenic transformants were selected. One specific transformant containing a 3-kb fragment of the pathogenic strain appeared to be dominantly enriched in diseased pigs. The observed enrichment was not tissue specific. The selected fragment, when introduced into two different weakly pathogenic strains, increased the virulence of these strains considerably. In contrast, introduction of the corresponding fragment of a weakly pathogenic strain had only minor effects on virulence. Nucleotide sequence analysis of the selected fragment of the pathogenic strain revealed the presence of two potential open reading frames, both of which were found to be mutated in the corresponding fragment of the weakly pathogenic strain. These data strongly suggest that the selected fragment contains determinants important for virulence.

Relatedness of Streptococcus suis isolates of various serotypes and clinical backgrounds as evaluated by macrorestriction analysis and expression of potential virulence traits

We evaluated the genetic diversity of Streptococcus suis isolates of different serotypes by macrorestriction analysis and elucidated possible relationships between the genetic background, expression of potential virulence traits, and source of isolation. Virulence traits included expression of serotype-specific polysaccharides, muramidase-released protein (MRP), extracellular protein factor (EF), hemolysin activity, and adherence to epithelial cells. Macrorestriction analysis of streptococcal DNA digested with restriction enzymes SmaI and ApaI allowed differentiation of single isolates that could be assigned to four major clusters, named A1, A2, B1, and B2. Comparison of the genotypic and phenotypic features of the isolates with their source of isolation showed that (i) the S. suis population examined, which originated mainly from German pigs, exhibited a genetic diversity and phenotypic patterns comparable to those found for isolates from other European countries; (ii) certain phenotypic features, such as the presence of capsular antigens of serotypes 2, 1, and 9, expression of MRP and EF, and hemolysin activity (and in particular, combinations of these features), were strongly associated with the clinical background of meningitis and septicemia; and (iii) isolates from pigs with meningitis and septicemia showed a significantly higher degree of genetic homogeneity compared to that for isolates from pigs with pneumonia and healthy pigs. Since the former isolates are considered highly virulent, this supports the theory of a clonal relationship among highly virulent strains.

A global profile of germline gene expression in C. elegans

We used DNA microarrays to profile gene expression patterns in the C. elegans germline and identified 1416 germline-enriched transcripts that define three groups. The sperm-enriched group contains an unusually large number of protein kinases and phosphatases. The oocyte-enriched group includes potentially new components of embryonic signaling pathways. The germline-intrinsic group, defined as genes expressed similarly in germlines making only sperm or only oocytes, contains a family of piwi-related genes that may be important for stem cell proliferation. Finally, examination of the chromosomal location of germline transcripts revealed that sperm-enriched and germline-intrinsic genes are nearly absent from the X chromosome, but oocyte-enriched genes are not.

The cps locus of Streptococcus suis serotype 2: genetic determinant for the synthesis of sialic acid

The capsule of S. suis serotype 2 is composed of glucose, galatose, N-acetylglucosamine, rhamnose and sialic acid. Recently, we described a major part of the cps2 locus of S. suis serotype 2. Based on sequence homology genes encoding potential glucosyl-, galactosyl-, N-acetylglucosaminyl- and rhamnosyltransferase activities could be identified. However, we did not find genes involved in the synthesis of sialic acid. Here, we describe the cloning and characterization of a remaining part of the cps2 locus. Based on the establish sequence 11 potential genes, designated orf2L, orf2M, orf2N, cps2O to cps2T, orf2U and orf2V were identified. A gene homologous to genes involved in the polymerization of the repeating oligosaccharide unit (cps2O) as well as genes involved in the synthesis of sialic acid (cps2P to cps2T) were identified. Moreover, hybridizing experiments showed that the genes involved in the sialic acid synthesis are present in S. suis serotype 1, 2, 14, 27 and 1/2. The orf2M and orf2N regions showed similarity to proteins involved in the polysaccharide biosynthesis of other Gram-positive bacteria. However, these regions seemed to be truncated or were non-functional as the result of frame-shift or point mutations. At its 3;-end the cps2 locus contained two insertional elements (orf2U and orf2V), both of which seemed to be non-functional.

Selection of recombinant antibodies specific for pathogenic Streptococcus suis by subtractive phage display

A semisynthetic antibody phage display library was used to select recombinant antibodies directed against surface components of a pathogenic strain of Streptococcus suis serotype 2 and against extracellular factor (EF), a protein known to be exclusively associated with pathogenic S. suis serotype 2 strains. Three distinct monoclonal phage antibodies directed against conformational epitopes of surface protein components of S. suis were selected. In addition, three different monoclonal phage antibodies were isolated that recognized EF. To isolate antibody fragments that recognize epitopes specific for a pathogenic S. suis serotype 2 strain, compared to a nonpathogenic serotype 2 strain, we applied a subtractive selection procedure. With this procedure, only one distinct phage antibody was found, and it was shown to be directed against EF. This demonstrates the selectivity of the applied procedure and confirms that EF is indeed differentially expressed by pathogenic and nonpathogenic strains. It also shows that EF is a very dominant antigen in phage antibody selections.

Distribution of capsular types and production of muramidase-released protein (MRP) and extracellular factor (EF) of Streptococcus suis strains isolated from diseased pigs in seven European countries

Streptococcus suis strains (n=411), isolated from diseased pigs in seven European countries were serotyped using specific antisera against serotype 1 to 28, and were phenotyped on the basis of their muramidase-released-protein (MRP) and extracellular-factor protein (EF) production. Overall, S. suis serotype 2 appeared to be most prevalent (32%), followed by serotype 9 (20%) and serotype 1 (12%). Serotype 2 was most frequently isolated in France, Italy and Spain, whereas serotype 9 was most frequently isolated in Belgium, The Netherlands and Germany. In the United Kingdom serotypes 1 and 14 were most frequently isolated. High percentages of S. suis serotype 1, 2, 1/2 and 14 strains, isolated from tissues associated with S. suis infections such as brain, serosa, joint, heart and organs expressed the EF-protein, indicating that in these serotypes expression of EF is likely to be associated with virulence. In contrast, strains belonging to serotype 7 and 9, isolated from tissues associated with S. suis infections did not produce EF. These results strongly suggest that in the serotypes 7 and 9 EF expression is not related to virulence. More than 80% of the S. suis serotype 9 strains produced an MRP* protein, a high molecular variant of the 136kDa MRP. Expression of MRP* in serotype 9 strains is possibly associated with virulence.

The fibronectin binding proteins of Staphylococcus aureus are required for adhesion to and invasion of bovine mammary gland cells

We recently described adhesion to and invasion of bovine mammary gland cells by Staphylococcus aureus in vitro. Here, we show that the levels of adhesion and invasion are dependent on the bacterial growth phase and are controlled by the agr locus. Incubation of exponential growth phase cells of S. aureus with mammary gland cells resulted in bacterial cell clumping. Strains of S. aureus deficient in expression of the fibronectin binding proteins (FnBPA and FnBPB) failed to clump and their ability to adhere to and to invade the bovine mammary gland cells is strongly reduced. This indicates that the fibronectin binding proteins are essential for S. aureus adhesion to and invasion of bovine mammary gland cells.

The cps genes of Streptococcus suis serotypes 1, 2, and 9: development of rapid serotype-specific PCR assays

We developed three type-specific PCR assays for the rapid and sensitive detection of Streptococcus suis serotype 1 (plus 14), serotype 2 (plus 1/2), and serotype 9 strains in tonsillar specimens from pigs. The PCR primers were based on the sequences of type-specific capsular genes of S. suis serotype 1, 2, and 9 strains. We recently characterized a major part of the capsular biosynthesis (cps) locus of S. suis serotype 2. Here we extended these studies and characterized major parts of the cps loci of S. suis serotypes 1 and 9. Type-specific genes were identified by cross-hybridization experiments between the individual cps genes and chromosomal DNAs from the 35 different serotypes. Four genes of S. suis serotype 1 specifically hybridized with serotype 1 and 14 strains only. Five genes of S. suis serotype 2 specifically hybridized with serotype 2 and 1/2 strains only, and two genes of S. suis serotype 9 specifically hybridized with serotype 9 strains. Until now rapid and sensitive diagnostic tests were available only for pathogenic strains of serotype 2 and highly pathogenic strains of serotype 1. The serotype-specific PCR assays can therefore be useful tools for the identification of serotype 1, 14, 2, 1/2, and 9 strains both for diagnostic purposes and in epidemiological and transmission studies. Therefore, these tests may facilitate control and eradication programs.

Rapid PCR test for Streptococcus suis serotype 7

Recent epidemiological studies on Streptococcus suis infections in pigs indicated that, besides serotypes 1, 2 and 9, serotype 7 is also frequently associated with diseased animals. For the latter serotype, however, no rapid and sensitive diagnostic methods are available. This hampers prevention and control programs. Here, we describe the development of a type-specific PCR test for the rapid and sensitive detection of S. suis serotype 7. The test is based on DNA sequences of capsular (cps) genes specific for serotype 7. These sequences were identified by cross-hybridization of several individual cps genes with the chromosomal DNAs of 35 different S. suis serotypes.

Evaluation of bottlenecks in the late stages of protein secretion in Bacillus subtilis

Despite a high capacity for secretion of homologous proteins, the secretion of heterologous proteins by Bacillus subtilis is frequently inefficient. In the present studies, we have investigated and compared bottlenecks in the secretion of four heterologous proteins: Bacillus lichenifomis alpha-amylase (AmyL), Escherichia coli TEM beta-lactamase (Bla), human pancreatic alpha-amylase (HPA), and a lysozyme-specific single-chain antibody. The same expression and secretion signals were used for all four of these proteins. Notably, all identified bottlenecks relate to late stages in secretion, following translocation of the preproteins across the cytoplasmic membrane. These bottlenecks include processing by signal peptidase, passage through the cell wall, and degradation in the wall and growth medium. Strikingly, all translocated HPA was misfolded, its stability depending on the formation of disulfide bonds. This suggests that the disulfide bond oxidoreductases of B. subtilis cannot form the disulfide bonds in HPA correctly. As the secretion bottlenecks differed for each heterologous protein tested, it is anticipated that the efficient secretion of particular groups of heterologous proteins with the same secretion bottlenecks will require the engineering of specifically optimized host strains.

Cell tropism of Staphylococcus aureus in bovine mammary gland cell cultures

Staphylococcus aureus is one of the most important pathogens of the bovine mammary gland. The interaction of S. aureus with cells of the bovine mammary gland is considered to play an essential role in the pathogenesis. In this study, we identified a new target cell for S. aureus adhesion and invasion. For that purpose, cells which compose the alveoli of the mammary gland were cultured. In these cultures, two morphologically different cell types, elongated and cubic cells, were observed. Adhesion and invasion of S. aureus was studied using microscopical and microbiological methods. S. aureus adhered specifically and in large numbers (about 300 bacteria/cell) to the elongated cell type. No adhesion to the cubic cell type was observed. In addition, bacteria were also found intracellularly in the elongated cells, and enclosed in membrane vesicles. Adhesion and invasion were time dependent and reached maximum levels after 4 h. Invasion was strongly reduced by staurosporine and genistein. The newly identified target cell was further characterized.

Detection of virulent strains of Streptococcus suis type 2 and highly virulent strains of Streptococcus suis type 1 in tonsillar specimens of pigs by PCR

We developed a PCR assay for the rapid and sensitive detection of virulent Streptococcus suis type 2 and highly virulent S. suis type 1 in tonsillar specimens from pigs. The PCR primers were based on the sequence of the gene encoding the EF-protein of virulent S. suis type 2 strains (MRP+EF+) and highly virulent S. suis type 1 strains (MRP(s)EF+) and of the EF protein of weakly virulent S. suis type 2 strains (MRP+EF). The latter strains give rise to larger PCR products than the virulent strains of S. suis type 1 and 2. A positive control template was included in the assay to identify false negative results. The PCR was evaluated using tonsillar specimens from herds known (or suspected) to be infected and herds without an S. suis history. The results obtained with the PCR assay were compared with the results obtained with a newly developed bacteriological examination. In this bacteriological examination we were able to identify the EF-positive strains directly in the tonsillar specimens. From the 99 tonsils examined, 48 were positive in the PCR and 51 negative. All specimens from which EF-positive S. suis strains were isolated were also positive in the PCR assay. Three samples were positive in the PCR, but negative by bacteriological examination. The results demonstrated that the PCR is a highly specific and sensitive diagnostic tool for the detection of pigs carrying virulent strains of S. suis type 2 and highly virulent strains of type 1. Application of the assay may contribute to the control of S. suis infections.

Identification and characterization of the cps locus of Streptococcus suis serotype 2: the capsule protects against phagocytosis and is an important virulence factor

To study the role of the capsule of Streptococcus suis serotype 2 in virulence, we generated two isogenic mutants disturbed in capsule production. For that purpose, we first cloned and characterized a major part of the capsular polysaccharide biosynthesis (cps) locus of S. suis serotype 2. Based on the established sequence, 14 open reading frames (ORFs), designated Orf2Z, Orf2Y, Orf2X, and Cps2A to Cps2K, were identified. Twelve ORFs belonged to a single transcriptional unit. The gene products of 11 of these ORFs showed similarity to proteins involved in polysaccharide biosynthesis of other gram-positive microorganisms. Nonencapsulated isogenic mutants were generated in the cps2B and cps2EF genes by insertional mutagenesis. In contrast to the wild-type S. suis serotype 2 strain, the nonencapsulated strains were highly sensitive to ingestion by porcine alveolar lung macrophages in vitro. More importantly, the nonencapsulated mutant strains were completely avirulent in young germfree pigs after intranasal inoculation. These observations indicate that the capsule of S. suis serotype 2 plays an essential role in the pathogenesis of S. suis serotype 2 infections.

Medical and social factors associated with the admission and discharge of acutely ill children

AIM

To examine medical and sociodemographic factors involved in acute paediatric admission. To compare outcome of admission with factors present at time of admission.

METHODS

Prospective questionnaire based study of 887 consecutive emergency general paediatric admissions to five Yorkshire hospitals during two separate three week periods in summer and winter.

MAIN OUTCOME MEASURES

Discharge diagnosis, length of stay.

RESULTS

Most admissions (53%) occurred "out of hours" with a peak during the evening. Two thirds (64%) of patients were under 3 years of age and clinical problems varied with age. Self referral via an accident and emergency department occurred in one third and was more likely after a fit in older children and in more socioeconomically deprived children. The most frequent presenting problems were breathing difficulty (24%), fit (16%), and feverish illness (15%). One quarter (24%) were discharged within 24 hours and 61% spent, at most, one night in hospital. Length of stay was shorter for night admissions and longer for children with a discharge diagnosis of asthma. Although most children had mild, self limiting illnesses, serious illness was subsequently found in 13% and could not be predicted from the presenting problems.

CONCLUSIONS

Current demand on emergency paediatric admission is mainly from young children with mild self limiting illnesses who spend one night or less in hospital. Changes in delivery of care to acutely ill children must take account of the pattern and nature of presenting problems and be rigorously audited to ensure that improvements in the health of children continue.

Parental and professional perception of need for emergency admission to hospital: prospective questionnaire based study

AIM

To compare views of parents, consultants, and general practitioners on severity of acute illness and need for admission, and to explore views on alternative services.

METHOD

Prospective questionnaire based study of 887 consecutive emergency paediatric admissions over two separate three week periods in summer and winter of five Yorkshire hospitals, combined with a further questionnaire on a subsample.

OUTCOME MEASURES

Parental scores of need for admission and parent and consultant illness severity scores out of 10. Consultant judgment of need for admission. Alternatives to admission considered by consultants and, for a subsample, by parents and family GP.

RESULTS

Ninety nine per cent of parents thought admission was needed. Parents scored need for admission more highly than severity of illness with no association observed between severity and presenting problem or diagnosis. High parental need score was associated with a fit, past illness, and length of stay. Consultant illness severity scores were skewed to the lower range. Consultants considered admission necessary in 71%, especially for children aged over 1 year, presentation with breathing difficulty or fit, and after a longer stay. More admissions in the evening were considered unnecessary as were admissions after longer preadmission illness, gastroenteritis, or upper respiratory tract infection. Of a subsample of parents, 81% preferred admission during the acute stage of illness even if home nursing had been available. Similar responses were obtained from GPs. Alternative services could have avoided admission for 19% of children, saving 15.6% of bed days used.

CONCLUSIONS

Medical professionals and parents differ in their views about admission for acute illnesses. More information is needed on children not admitted. Alternative services should take account of patterns of illness and should be acceptable to parents and professionals; cost savings may be marginal.

The TAPS Project 41: homes for life? Residential stability five years after hospital discharge. Team for the Assessment of Psychiatric Services

This paper describes pathways followed by 567 long-stay patients who were resettled into the community, as part of a program to close two psychiatric hospitals in London and replace them with community-based services. Sixty-one percent of the former patients remained in their original placement--mostly group homes--over the five-year follow-up. Transition from one house to another mostly took a direct course, with only 27 patients changing houses by way of long intermediate hospitalisation. Change of residence was at the same level of support, with only a slight trend towards less supervised facilities. Ten patients could not be traced and have possibly become homeless. Only 3 patients were in prison during the five-year follow-up. More than a third of the sample were readmitted at least once during that period. It is concluded that community residences established under the resettlement program served as relatively stable homes for the majority of patients.

Identification of protein-protein interactions of the major sperm protein (MSP) of Caenorhabditis elegans

In nematodes, sperm are amoeboid cells that crawl via an extended pseudopod. Unlike those in other crawling cells, this pseudopod contains little or no actin; instead, it utilizes the major sperm protein (MSP). In vivo and in vitro studies of Ascaris suum MSP have demonstrated that motility occurs via the regulated assembly and disassembly of MSP filaments. Filaments composed of MSP dimers are thought to provide the motive force. We have employed the yeast two-hybrid system to investigate MSP-MSP interactions and provide insights into the process of MSP filament formation. Fusions of the Caenorhabditis elegans msp-142 gene to both the lexA DNA binding domain (LEXA-MSP) and a transcriptional activation domain (AD-MSP) interact to drive expression of a lacZ reporter construct. A library of AD-MSP mutants was generated via mutagenic PCR and screened for clones that fail to interact with LEXA-MSP. Single missense mutations were identified and mapped to the crystal structure of A. suum MSP. Two classes of mutations predicted from the structure were recovered: changes in residues critical for the overall fold of the protein, and changes in residues in the dimerization interface. Multiple additional mutations were obtained in the two carboxy-terminal beta strands, a region not predicted to be involved in protein folding or dimer formation. Size fractionation of bacterially expressed MSPs indicates that mutations in this region do not abolish dimer formation. A number of compensating mutations that restore the interaction also map to this region. The data suggest that the carboxy-terminal beta strands are directly involved in interactions required for MSP filament assembly.

Virulence of Streptococcus suis type 2 for mice and pigs appeared host-specific

A murine model for Streptococcus suis infection in pigs was validated by inoculating groups of 5 BALB/c and 5 CF1 mice with 10(7) CFU/ml of 13 different S. suis serotype 2 strains. The pathogenicity of these strains had been established in a standardized pig model of S. suis infection using one-week-old gnotobiotic pigs. We inoculated groups of mice intraperitoneally with 4 strains that were highly virulent for pigs and belonged to the phenotype MRP+EF+, with 4 strains, that were weakly virulent for pigs and belonged to the phenotype MRP+EF+, and with 5 strains that were non-virulent for pigs and belonged to phenotype MRP-EF-. The S. suis strains that were highly virulent for pigs caused high morbidity and an intermediate mortality in mice, the S. suis strains that were weakly virulent for pigs caused high morbidity but low mortality, and the strains that were non-virulent for pigs, induced highest morbidity and mortality. These results were comparable in both breeds of mice. In contrast to the pathology of S. suis infection in pigs with specific lesions, lesions in mice were histologically often characterized as non-specific, i.e., necrotizing encephalitis and focal or diffuse hepatitis sometimes with abscesses. Irrespective of breed (BALB/c vs. CF1), the murine model used for S. suis infection was incompatible with the pig model. This indicates that virulence of S. suis type 2 for mice and pigs is host-specific. Therefore, we regard the presently available murine models unsuitable for studying S. suis infections in pigs.

Virulent strains of Streptococcus suis serotype 2 and highly virulent strains of Streptococcus suis serotype 1 can be recognized by a unique ribotype profile

The ribotype profiles of 42 different Streptococcus suis strains were studied. These strains belonged to five serotypes and differed in their virulence for pigs as well as in the expression of the muramidase-released protein and the extracellular protein factor. For the ribotyping, chromosomal DNAs were digested with EcoRI and were hybridized with a 1,066-bp ribosomal DNA probe. The hybridization patterns showed genetic heterogeneity within and between the serotypes. Pathogenic strains of serotype 2 and highly pathogenic strains of serotype 1 could be recognized by their unique ribotype profiles. Nonpathogenic strains showed a high degree of genetic heterogeneity. Moreover, by comparing the 16S ribosomal DNA sequences of a number of S. suis strains, we were able to design two DNA probes which specifically hybridized with S. suis strains.

Appropriateness of acute medical admissions and length of stay

OBJECTIVE

To use the Appropriateness Evaluation Protocol (AEP) to assess the extent of inappropriate utilisation of hospital beds by acute medical patients. To determine whether clinicians viewed the AEP decisions as valid.

DESIGN

Retrospective review of the medical records of a 10% random sample of 8,210 patients admitted as medical emergencies. An objective independent review instrument (AEP) was used to assess the medical necessity for hospitalisation at admission and on each subsequent day. To test the validity of the screening instrument, a subsample of the reviewed records was further assessed by a panel of physicians.

SETTING

A district general hospital in the West Midlands region of England.

SUBJECTS

Eight hundred and twenty-one adult patients admitted to general medicine during one calendar year.

MAIN OUTCOME MEASURES

Proportions of admissions and days of care for which inpatient medical care was judged appropriate. Reasons for inappropriate utilisation and potential bed-days that could be saved by the development and use of alternative services were also considered. Validity of the AEP was tested by assessing agreement between the majority decision of an expert panel and the criterion-based AEP decision.

RESULTS

AEP identified 51/821 (6%) admissions and 2,195/4,885 (45%) days of care as inappropriate. Over half the patients had a hospital stay in which at least half the days were judged inappropriate. The commonest reason for inappropriate days was remaining in hospital after the medical purpose for admission had been accomplished. This accounted for 38% of inappropriate days reviewed. In validity testing there was a high level of agreement between the physicians and the AEP, with kappa values greater than 0.80 for admissions and days of care.

CONCLUSIONS

The AEP is a valid and useful instrument for assessing the utilisation of acute medical beds in a NHS hospital. In this study acute medical admissions were largely appropriate at the time of admission but a substantial proportion of subsequent days of care was considered inappropriate by AEP criteria. Most inappropriate utilisation was due to organisational issues within the hospital. As a result of this study, several service and policy developments were identified that should improve the efficiency of bed utilisation at the hospital.

Radiation protection systems for the final focus test beam at SLAC

The Final Focus Test Beam (FFTB) is a new beam line at the Stanford Linear Accelerator Center designed to test new beam optics concepts, hardware, and techniques necessary to achieve and measure the small spot sizes required for future generations of high-energy e+e- linear colliders. The FFTB takes a 47 GeVc-1, 1 kW electron beam at the end of the Stanford Linear Accelerator Center linear accelerator and transports it to the FFTB beam dump. A radiation protection system was designed and installed for the FFTB with the primary goal that the integrated dose equivalent outside the shielding resulting from beam loss would not exceed 10 mSv y-1. This system is comprised of shielding, a beam containment system and a personnel protection system. This paper presents various aspects of radiation safety at Stanford Linear Accelerator Center that were considered in the design of the FFTB radiation protection system. Beam tests were conducted in which the performance of various beam containment devices and the shielding effectiveness were evaluated. Preliminary results from these tests are presented.

Mutants of Streptococcus suis types 1 and 2 impaired in expression of muramidase-released protein and extracellular protein induce disease in newborn germfree pigs

The contribution of muramidase-released protein (MRP) and extracellular factor (EF) to the virulence of Streptococcus suis type 1 and 2 infections was studied. For that aim, we constructed mutants of S. suis types 1 and 2 by inactivating the genes encoding MRP and EF. Moreover, we changed a type 2 strain producing the 110-kDa EF protein into a strain producing a modified protein (EF*) of increased molecular mass. The chromosomally located mrp and epf genes were inactivated by replacement recombination by using nonreplicative plasmids. Newborn germfree pigs were inoculated with pathogenic type 1 and 2 strains and with the isogenic mutant strains. Wild-type as well as mutant strains induced fever, specific signs of disease, and lesions. Moreover, all mutant strains could be reisolated from the central nervous system of infected pigs. These results showed that inactivation or alteration of the mrp and epj genes had no measurable effect on the pathogenicity of S. suis types 1 and 2.

Characterization of virulence of the Streptococcus suis serotype 2 reference strain Henrichsen S 735 in newborn gnotobiotic pigs

Strain Henrichsen S 735 (NCTC 10234) of Streptococcus suis serotype 2 reference and three other such strains (strains S 4005, S 3921 and T 141) were tested for virulence by inoculating pigs intranasally and intravenously. The taxonomical properties of each strain were determined. Phenotypes were determined by Western blotting based on MRP and EF protein expression and genotypes were determined by Southern hybridization analysis of the mrp and epf genes. Reference strain S 735 and strain S 3921 produced the 136 kDa MRPh and a 180 kDa form of EF, and hence these strains belong to the MRP + EF phenotype. In accordance with previous experiments with this phenotype, strains S 735 and S 3921 appeared to be only weakly virulent for newborn gnotobiotic pigs. Strain S 4005 produced the 136 kDa MRP and the 110 kDa form of EF, hence it belongs to the MRP + EF + phenotype. This strain was highly virulent for pigs. Strain T 141 did not produce MRP or EF, and hence belongs to the MRP-EF- phenotype. It was nonvirulent for pigs. The route of inoculation did not influence the frequency or severity of clinical signs of disease or lesions, which demonstrated that the 110 kDa EF is not essential during invasion. Southern blot analysis showed that all four S. suis type 2 strains contain sequences that are homologous to the epf and mrp genes. For studies on pathogenesis of S. suis type 2 infections in pigs, we recommend the use of strains that have been tested in a standardized pig model and that belong to the MRP + EF + phenotype, such as strain S 4005.

Histopathological changes in the lymphoid tissues of sheep exposed to the bovine immunodeficiency-like virus

Six yearling sheep were inoculated intraperitoneally with peripheral blood from two sheep infected with the bovine immunodeficiency-like virus (BIV) strain R29. An additional five sheep served as sham-inoculated controls. Of the six sheep given BIV, five seroconverted, one of them remaining seropositive for the duration of the study. The polymerase chain reaction demonstrated BIV provirus in three of the five serologically positive animals. At necropsy, 1 year after inoculation, histological changes were found only in the lymphoid tissues. In sheep exposed to BIV, mild though significant increases were seen in the (1) number of splenic periarteriolar lymphoid sheaths, (2) number of secondary follicles in hilar and prescapular or popliteal lymph nodes, and (3) medullary sinus cellularity in prescapular and popliteal lymph nodes.

Use of Multiscreen plates for the preparation of bacterial DNA suitable for PCR

A rapid and inexpensive method for isolating bacterial DNA for use in PCR is described. The method is based on the guanidinium thiocyanate (GuSCN)-lysis method of Boom et al. (J. Clin. Microbiol. 28:495-503, 1990) and enables a multiple of 96 samples to be prepared in only one hour. We use Multiscreen plates and a vacuum manifold from Millipore. Clinical samples are lysed and washed in the wells of a Multiscreen plate, and DNA is eluted in a standard microplate. Purified DNA was recovered with high yields (over 25%). The method allows multichannel or robotic pipetting for both the sample preparation as well as for the PCR step. The method has been applied successfully to detect pathogenic Streptococcus suis type 2 in nasal and tonsil swab specimens of pigs.

Tissue-specific pharmacology of testosterone and 5 alpha-dihydrotestosterone analogues: characterization of a novel canine liver androgen-binding protein

The mechanism by which the hormones 5 alpha-dihydrotestosterone and testosterone differentially regulate such diverse functions as development of male internal and external genitalia and maintenance of prostatic growth via a single androgen receptor (AR) is not well understood. To search for potential AR isoforms, an extensive pharmacological survey of the binding of [3H]mibolerone (7 alpha,17 alpha-[3H]dimethyl-19-nortestosterone) in dog prostate, adrenal gland, testis, liver, kidney, brain, muscle, and spleen cytosolic extracts was carried out. The antagonist androst-4-en-3,17-dione (ATD), as well as a series of unsaturated analogues of testosterone, exhibited marked tissue specificity for binding to mibolerone-binding proteins (MBPs), with ATD having a 10-fold higher affinity for the MBPs present in liver than for those in prostate and testis. The difference in affinity was not due to tissue-specific metabolism of ATD. Competition binding profiles for ATD with mixtures of prostate and liver extracts were consistent with two distinct populations of binding sites. Both wild-type human AR-B and the recently discovered human AR-A isoform were expressed in COS cells and were found to exhibit pharmacology similar to that of the prostatic MBPs in dogs. Analogues of ATD or testosterone could prove to be useful probes for delineating the differential effects of 5 alpha-dihydrotestosterone and testosterone on the biological actions of the AR and related proteins.