Aeromonas salmonicida infection kinetics and protective immune response to vaccination in sablefish (Anoplopoma fimbria)

Effective vaccine programs against Aeromonas salmonicida have been identified as a high priority area for the sablefish (Anoplopoma fimbria) aquaculture. In this study, we established an A. salmonicida infection model in sablefish to evaluate the efficacy of commercial vaccines and an autogenous vaccine preparation. Groups of 40 fish were intraperitoneally (ip) injected with different doses of A. salmonicida J410 isolated from infected sablefish to calculate the median lethal dose (LD₅₀). Samples of blood, head kidney, spleen, brain, and liver were also collected at different time points to determine the infection kinetics. The LD₅₀ was estimated as ~3 × 10⁵ CFU/dose. To evaluate the immune protection provided by an autogenous vaccine and two commercial vaccines in a common garden experimental design, 140 fish were PIT-tagged, vaccinated and distributed equally into 4 tanks (35 fish for each group, including a control group). Blood samples were taken every 2 weeks to evaluate IgM titers. At 10 weeks post-immunization, all groups were ip challenged with 100 times the calculated LD₅₀ for A. salmonicida J410. A. salmonicida was detected after 5 days post-infection (dpi) in all collected tissues. At 30 days post-challenge the relative percentage survival (RPS) with respect to the control group was calculated for each vaccine. The RPS for the bacterin mix was 65.22%, for Forte Micro 4® vaccine was 56.52% and for Alpha Ject Micro 4® was 30.43%, and these RPS values were reflected by A. salmonicida tissue colonization levels at 10 days post-challenge. Total IgM titers peaked at 6-8 weeks post-immunization, where the autogenous vaccine group showed the highest IgM titers and these values were consistent with the RPS data. Also, we determined that the A. salmonicida A-layer binds to immunoglobulins F(ab)' in a non-specific fashion, interfering with immune assays and potentially vaccine efficacy. Our results indicate that vaccine design influences sablefish immunity and provide a guide for future sablefish vaccine programs.

Prenatal diagnosis and prognosis of accelerated idioventricular rhythm

OBJECTIVES

As postnatal identification of accelerated idioventricular rhythm (AIVR) relies on specific electrocardiographic patterns, prenatal diagnosis of this condition is challenging and its true incidence is unknown. The objectives of this study were to evaluate the performance of prenatal ultrasonography in identifying intrauterine cardiocirculatory events linked to specific electrocardiographic signs of postnatal AIVR, including left or right ventricular origin, and to assess the prenatal prognosis of this arrhythmia.

METHODS

We reviewed Doppler tracings from the superior vena cava/ascending aorta (SVC/Ao), ductus venosus (DV), ductus arteriosus (DA) and aortic isthmus (AoI), as well as simultaneous M-mode recordings of septal and left ventricular wall motions of fetuses diagnosed with AIVR from January 2004 to December 2014.

RESULTS

Three cases of AIVR were identified among 27 912 fetuses. SVC/Ao Doppler flow recordings revealed atrioventricular dissociation (ventricular rates within 20% of atrial rates) in all three fetuses and episodes of isorhythmic atrioventricular dissociation in one, while M-mode confirmed normal left ventricular shortening fraction in all cases. Fusion beats were observed on AoI tracing in one fetus, while simultaneous recordings of AoI and DA revealed signs of right bundle branch block in one case and left bundle branch block in the other two. On DV Doppler recordings, retrograde a-waves in the presence of simultaneous atrial and ventricular contractions were observed in all three fetuses, leading to an increase in central venous pressure in all and hydrops fetalis in two cases without evidence of ventricular dysfunction.

CONCLUSIONS

Echocardiographic criteria required for postnatal diagnosis of AIVR can be documented in utero using specific ultrasonographic approaches. During fetal life, AIVR may not be a benign entity. Hydrops fetalis is frequently associated with AIVR because of increase in central venous pressure related to simultaneous atrioventricular contractions; thus, the ultrasonographic investigation protocol of fetuses with unexplained hydrops fetalis should aim at ruling out AIVR and include Doppler flow recordings in SVC/Ao, DV, AoI, DA and umbilical vein. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Profiling left and right ventricular proportional output during fetal life with a novel systolic index in the aortic isthmus

OBJECTIVE

Left ventricular ejection causes forward flow in the fetal aortic isthmus while the right ventricle has a retrograde influence. The aim of this study was to create reference values for an isthmic systolic index (ISI) reflecting the changing influence of right and left ventricular performance on Doppler flow velocity waveforms of the aortic isthmus throughout normal pregnancy.

METHODS

Doppler recordings of 260 normal fetuses with a gestational age of 18-37 weeks were reviewed. Peak systolic velocity (PSV) and end-systolic velocity (or systolic nadir; Ns) were measured on all aortic isthmus waveforms. An ISI was derived from the ratio Ns/PSV. Left and right ventricular outputs were also calculated.

RESULTS

Up to 22-23 weeks' gestation, the mean ISI is stable at around 0.2. At about 28 weeks, a brief end-systolic deceleration wave is observed on the aortic isthmus waveforms, progressing steadily with gestation and causing a fall of ISI towards a mean value of zero between 30 and 31 weeks. This trend continues thereafter and a mean value of -0.4 was observed at the end of pregnancy. An inverse correlation was found between right ventricular output and Ns (r = -0.334, P = 0.001). Simultaneous recordings of the isthmus and the ductus arteriosus Doppler waveforms demonstrated that the primary cause of the end-systolic deceleration and ultimate reversal of flow at the isthmus is the increasingly dominant flow from the right ventricle.

CONCLUSION

The transitional changes of the respective right and left ventricular outputs throughout pregnancy are well profiled by the ISI. This index highlights the physiological increase in fetal right ventricle flow preponderance as pregnancy progresses. Alteration of the ISI profile could be expected in clinical conditions associated with unbalanced alteration of the fetal ventricular outputs.

Thrombospondin-1 Deficiency Exacerbates the Pathogenesis of Diabetic Retinopathy

Diabetic retinopathy is a leading cause of blindness in the United States. Access to new animal models that exhibit retinal vasculopathies with short duration of diabetes, are vital for understanding the underlying mechanisms and examining the efficacy of new treatment modalities. Our previous studies demonstrated decreased expression of Thrombospondin-1 (TSP1), an endogenous inhibitor of angiogenesis, in eyes from both patients and rodents with diabetes. Here we examined whether TSP1 deficiency could exacerbate diabetic retinal vasculopathies. Akita/+ male mice reproducibly develop diabetes by 4 weeks of age. These mice demonstrated the early non-proliferative stages of diabetic retinopathy, including decreased numbers of pericytes and increased glial cell activation. However, Akita/+ male mice deficient in TSP1 (Akita/+; TSP1-/-) demonstrated more advanced stages of diabetic retinopathy with a 4-fold increase in acellular capillaries and increased fibronectin and GFAP expression. These vascular changes were not attributable to aberrant retinal vascular development in the absence of TSP1, since down-regulation of TSP1 postnatally in the endothelium also resulted in more severe retinopathy. In addition, lack of another endogenous inhibitor of angiogenesis, pigment epithelium derived factor (PEDF), also enhanced diabetic retinopathy in Akita/+ mice. Akita/+; PEDF-/- male mice demonstrated increased numbers of acellular capillaries compared to controls but at a level lower than that observed in Akita/+; TSP1-/- mice. Thus, the exacerbation of diabetic retinopathy in Akita/+; TSP1-/- mice will allow the study of retinal vasculopathies with a shorter duration of diabetes and facilitate future testing of treatment modalities that protect the retinal vasculature and preserve sight.

Physiologic and molecular consequences of endothelial Bmpr2 mutation

Background

Pulmonary arterial hypertension (PAH) is thought to be driven by dysfunction of pulmonary vascular microendothelial cells (PMVEC). Most hereditary PAH is associated with BMPR2 mutations. However, the physiologic and molecular consequences of expression of BMPR2 mutations in PMVEC are unknown.

Methods

In vivo experiments were performed on adult mice with conditional endothelial-specific expression of the truncation mutation Bmpr2^delx4+, with age-matched transactivator-only mice as controls. Phenotype was assessed by RVSP, counts of muscularized vessels and proliferating cells, and staining for thromboses, inflammatory cells, and apoptotic cells. The effects of BMPR2 knockdown in PMVEC by siRNA on rates of apoptosis were assessed. Affymetrix expression arrays were performed on PMVEC isolated and cultured from triple transgenic mice carrying the immortomouse gene, a transactivator, and either control, Bmpr2^delx4+ or Bmpr2^R899X mutation.

Results

Transgenic mice showed increased RVSP and corresponding muscularization of small vessels, with histologic alterations including thrombosis, increased inflammatory cells, increased proliferating cells, and a moderate increase in apoptotic cells. Expression arrays showed alterations in specific pathways consistent with the histologic changes. Bmpr2^delx4+ and Bmpr2^R899X mutations resulted in very similar alterations in proliferation, apoptosis, metabolism, and adhesion; Bmpr2^delx4+ cells showed upregulation of platelet adhesion genes and cytokines not seen in Bmpr2^R899X PMVEC. Bmpr2 mutation in PMVEC does not cause a loss of differentiation markers as was seen with Bmpr2 mutation in smooth muscle cells.

Conclusions

Bmpr2 mutation in PMVEC in vivo may drive PAH through multiple, potentially independent, downstream mechanisms, including proliferation, apoptosis, inflammation, and thrombosis.

Impressions of breastfeeding information and support among first-time mothers within a multiethnic community

The purpose of this study was to document mothers' perceptions of breastfeeding information and support received from hospital- and community-based health professionals within a multiethnic community. A telephone survey was conducted to assess: mothers' impressions of professional support for breastfeeding, whether recommended breastfeeding practices were followed by health professionals, and the nature and sources of breastfeeding information received. An ethnically diverse sample of 108 first-time breastfeeding mothers was surveyed at 3 weeks postpartum. Overall, the mothers' evaluations of professional support for breastfeeding were positive, even though they reported breastfeeding practices that fell short of recommended standards. Immigrant mothers were found more likely to experience hospital practices detrimental to breastfeeding success than Canadian-born mothers, but were also found more likely to receive professional breastfeeding support in the community. Significant differences were also found between immigrant and Canadian-born mothers in the sources of their breastfeeding information. The findings underscore the key role of nurses in ensuring the promotion and optimal support of breastfeeding.

The oral cavity as a reservoir of bacterial pathogens for focal infections

Dental procedures, but more importantly, oral infections and poor oral health can provoke the introduction of oral microorganisms into the bloodstream or the lymphatic system. The subsequent attachment and multiplication of these bacteria on tissues or organs can lead to focal oral infections. Pathogenic agents may also remain at their primary oral site but the toxins liberated can reach an organ or tissue via the bloodstream and cause metastatic injury. Finally, metastatic inflammation may result from an immunological injury caused by oral bacteria or their soluble products that enter the bloodstream and react with circulating specific antibodies to form macromolecular complexes.

Inhibition of the activities of matrix metalloproteinases 2, 8, and 9 by chlorhexidine

Matrix metalloproteinases (MMPs) are a host cell-derived proteolytic enzyme family which plays a major role in tissue-destructive inflammatory diseases such as periodontitis. The aim of the present study was to evaluate the inhibitory effect of chlorhexidine (CHX) on MMP-2 (gelatinase A), MMP-9 (gelatinase B), and MMP-8 (collagenase 2) activity. Heat-denatured type I collagen (gelatin) was incubated with pure human MMP-2 or -9 activated with p-aminophenylmercuric acetate (APMA), and the proteolytic degradation of gelatin was monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Coomassie blue staining. The effect of CHX on MMP-8 activity was also studied with a cellular model addressing the ability of phorbol myristate acetate (PMA)-triggered human peripheral blood neutrophils (polymorphonuclear leukocytes [PMNs]) to degrade native type I collagen. CHX inhibited the activities of both gelatinases (A and B), but MMP-2 appeared to be more sensitive than MMP-9. Adding calcium chloride to the assay mixtures almost completely prevented the inhibition of MMP-9 activity by CHX, while the inhibition of MMP-2 activity could be reversed only when CHX was used at a low concentration. This observation suggests that CHX may act via a cation-chelating mechanism. CHX dose-dependently inhibited collagenolytic activity of MMP-8 released by PMA-triggered PMNs. MMP-8 without APMA activation was inhibited clearly more efficiently than APMA-activated MMP-8. Our study suggests that the direct inhibition of the MMPs' activities by CHX may represent a new valuable effect of this antimicrobial agent and explains, at least in part, the beneficial effects of CHX in the treatment of periodontitis.

Effect of microbial siderophores on matrix metalloproteinase-2 activity

Matrix metalloproteinases (MMPs) are capable of cleaving almost all macromolecules of the extracellular connective tissue matrix and are thought to play a major role in tissue destructive inflammatory diseases such as periodontitis. The aim of this study was to determine the effects of siderophores, which are iron-chelating molecules produced by a variety of microorganisms, on the activity of MMP-2. Heat-denatured type I collagen (gelatin) was incubated with p-aminophenylmercuric acetate-activated MMP-2 and siderophores. Degradation of gelatin was monitored by SDS-PAGE and Coomassie blue staining. Ferrichrome, rhodotorulic acid, desferoxamine mesylate and 2,3-dihydroxybenzoic acid were found to inhibit the MMP-2 activity whereas beta-phenylpyruvic acid had no effect. The inhibition could be reversed by adding an excess calcium chloride or ferric chloride to the assay mixtures. Our study suggests that microbial siderophores may represent new-potential therapeutic molecules for the treatment of destructive inflammatory diseases involving excess MMP-2 activity, such as periodontitis.

Regulated pre-employment medical examinations and their effect on the utilization of health services: the experience of 1,498 police cadets, Quebec, 1988

Persons seeking employment in a police department must submit to a pre-induction medical screening after they have qualified on a compulsory test of physical stamina. The effect of this imposition on the utilization of health services was studied in a group of 1,498 police cadets whose use of medical and optometric services was monitored over a period of one year and compared with that of the general population of the same age and sex. Cadets have used about as much care as women of child-bearing age and were almost all exposed to physiological and radiological procedures that have no known utility in the medical surveillance of workers. It is estimated that the cost of providing the protection that is apparently sought by the regulation varies between $6,285 and $66,000 per person.

Trisomy 15 with loss of the paternal 15 as a cause of Prader-Willi syndrome due to maternal disomy

Uniparental disomy has recently been recognized to cause human disorders, including Prader-Willi syndrome (PWS). We describe a particularly instructive case which raises important issues concerning the mechanisms producing uniparental disomy and whose evaluation provides evidence that trisomy may precede uniparental disomy in a fetus. Chorionic villus sampling performed for advanced maternal age revealed trisomy 15 in all direct and cultured cells, though the fetus appeared normal. Chromosome analysis of amniocytes obtained at 15 wk was normal in over 100 cells studied. The child was hypotonic at birth, and high-resolution banding failed to reveal the deletion of 15q11-13, a deletion which is found in 50%-70% of patients with PWS. Over time, typical features of PWS developed. Molecular genetic analysis using probes for chromosome 15 revealed maternal disomy. Maternal nondisjunction with fertilization of a disomic egg by a normal sperm, followed by loss of the paternal 15, is a likely cause of confined placental mosaicism and uniparental disomy in this case of PWS, and advanced maternal age may be a predisposing factor.