Identification of novel DYNC2H1 mutations associated with short rib-polydactyly syndrome type III using next-generation panel sequencing

Short rib-polydactyly syndrome type III (SRPS3) is a perinatal lethal skeletal disorder with polydactyly and multisystem organ abnormalities. While ultrasound of the fetus can detect skeletal abnormalities characteristic of SRPS3, the syndrome is often difficult to diagnose before birth. As SRPS3 is an autosomal recessive disorder, identification of the gene mutations involved could lead to the development of prenatal genetic testing as an accurate method of diagnosis. In this study, we describe genetic screening approaches to identify potential abnormalities associated with SRPS3. Karyotype analysis, array comparative genomic hybridization (aCGH), and next-generation panel sequencing were each performed on a fetus showing signs of the disorder, as well as on the mother and father. Karyotype and aCGH results revealed no abnormalities. However, next-generation panel sequencing identified novel mutations in the DYNC2H1 gene. The fetus was compound heterozygous for both a missense mutation c.8313A > T and a frameshift mutation c.10711_10714delTTTA in the DYNC2H1 gene, which were inherited from the mother and father, respectively. These variants were further confirmed using Sanger sequencing and have not been previously reported. Our study indicates the utility of using next-generation panel sequencing in screening for novel disease-associated mutations.

Analysis of household data on influenza epidemic with Bayesian hierarchical model

Data used for modelling the household transmission of infectious diseases, such as influenza, have inherent multilevel structures and correlated property, which make the widely used conventional infectious disease transmission models (including the Greenwood model and the Reed-Frost model) not directly applicable within the context of a household (due to the crowded domestic condition or socioeconomic status of the household). Thus, at the household level, the effects resulting from individual-level factors, such as vaccination, may be confounded or modified in some way. We proposed the Bayesian hierarchical random-effects (random intercepts and random slopes) model under the context of generalised linear model to capture heterogeneity and variation on the individual, generation, and household levels. It was applied to empirical surveillance data on the influenza epidemic in Taiwan. The parameters of interest were estimated by using the Markov chain Monte Carlo method in conjunction with the Bayesian directed acyclic graphical models. Comparisons between models were made using the deviance information criterion. Based on the result of the random-slope Bayesian hierarchical method under the context of the Reed-Frost transmission model, the regression coefficient regarding the protective effect of vaccination varied statistically significantly from household to household. The result of such a heterogeneity was robust to the use of different prior distributions (including non-informative, sceptical, and enthusiastic ones). By integrating out the uncertainty of the parameters of the posterior distribution, the predictive distribution was computed to forecast the number of influenza cases allowing for random-household effect.

Autism spectrum disorders: a qualitative study of attitudes toward prenatal genetic testing and termination decisions of affected pregnancies

In the United States, prenatal genetic testing (PGT) for Autism Spectrum Disorders (ASD) is currently available via clinical genetic services. Such testing may inform parents about their unborn child's risk for ASD, prepare parents for the birth of an affected infant, and allow them to arrange for early interventions. Although PGT for autism has potential benefits, the associated ethical, legal, and social implications (ELSI) should be considered. This first qualitative study employed a hypothetical scenario to explore the attitudes toward PGT and termination decisions of 42 parents of children with ASD. Over half of the participants expressed willingness to undergo PGT for autism. Reasons included better preparation for birth, early and better treatment, termination of affected pregnancy, contribution to research, and curiosity. Of the 31 parents who were either willing or unsure about undergoing the PGT, approximately three-fourths would continue their hypothetical affected pregnancies. Explanations included preparation for birth of the child, bonding or acceptance of existing ASD-affected children, apprehensions about test limitations, and religious concerns. Parents who reported they would terminate the affected pregnancy in this hypothetical situation were primarily Asians. This study contributes to the growing understanding of the ELSI aspects of PGT in clinical practice.

Autism spectrum disorders: perceptions of genetic etiology and recurrence risk among Taiwanese parents of affected children

In Taiwan, autism spectrum disorders (ASDs) are an emerging public health concern. The ongoing scientific progress for understanding the genetic etiology of ASD makes it increasingly important to examine how parents of children with ASD perceive the causes and recurrence risk of having another child with ASD. These perceptions may influence their family planning, attitudes toward genetic services, and willingness to take their children for ASD genetic testing. However, previous studies addressing this issue were conducted primarily in Western countries. As culture might shape an individual's views of genetic/genomic disorders, this first-of-its-kind study examined the perceptions of the genetic etiology for ASD and the recurrence risk among Taiwanese parents of children affected with ASD. In-depth, semi-structured interviews were conducted among 39 parents having at least one child with ASD. Although the majority of participants believed that ASD has a genetic link, less than half perceived genetic factors as the cause of their own child's ASD. Moreover, most participants articulated their recurrence risk incorrectly. Some parents were concerned about their doctors' limited genomic competencies. To provide parents with better education, counseling, and support for making reproductive decisions, ASD-related genomic education among Taiwanese physicians is needed.

Genomics education for health educators in Texas: the Family Health History Training Program

AIMS

This paper describes the development and pilot-testing of The Family Health History Training Program for Health Educators (FHHTP). Although in recent years professional organizations have urged the health promotion workforce to adopt genomics-related competencies, training opportunities designed specifically for health educators (HEs) remain scarce. Designed by a team of HEs, the FHHTP aims at preparing HEs in the state of Texas, USA, to use a family health history as a genomic health promotion tool.

METHODS

In this report, we describe (a) the program's empirical and theoretical grounding, (b) its components, and (c) pilot-testing of the 2 main components (Web-based and workshop trainings). The FHHTP addresses the training needs expressed by HEs and anchors itself in a theoretical model previously tested with 1,607 US-based HEs. The model draws from Social Cognitive Theory, the Theory of Planned Behavior, and Diffusion of Innovations theory. The program comprises 6 elements; the Web-based training and the training workshops are the focus of this paper.

RESULTS

Pilot data indicate participants' knowledge and intention improved significantly (p < 0.05) at post-test and remained significantly higher at the 3-month follow-up. Attitudes, self-efficacy, behavior, knowledge/awareness, and intention also exhibited improvement in scores over time.

CONCLUSION

We conclude, therefore, that the FHHTP can contribute significantly to the adoption of genomic competencies by Texas HEs. This report describes how the first-of-its-kind genomics training for HEs in the USA - FHHTP - was developed and pilot-tested with HEs in Texas.

Response characteristics of Scirpus trioueter and its rhizosphere to pyrene contaminated soils at different growth stages

Scirpus triqueter (Triangular club-rush), a typical wetland species, is used to study the response characteristics to pyrene. A pot experiment was conducted to investigate the growth parameters (height, diameter, shoot number, total volume, underground biomass, above-ground biomass and total biomass), and enzymes (catalase and superoxide dismutase) of S. triqueter. The characteristics of soil enzymes (catalase and polyphenol oxidase) and microorganisms (bacteria and fungi) were also assessed after pyrene treatment. Elevated pyrene concentration (80 mgkg(-1)) in the soil reduced the shoot number and biomass significantly, especially at the early growth stage. In root tissue, the enzyme catalase was activated at 80 mgkg(-1) of pyrene. Compared to roots, shoots had higher enzyme activities. Catalase activities in the rhizosphere increased throughout the growth period of S. triqueter. Polyphenol oxidase activities in the rhizosphere were higher than those in the bulk soil and unplanted soil. The populations of bacteria (total bacteria, pyrene-tolerant bacteria, and actinomyces) and fungi decreased under the stress of high pyrene concentration, while that of pyrene-tolerant bacteria increased with the increasing pyrene concentration. The presence of pyrene did not benefit the growth of S. triqueter. S. triqueter and soil enzymes varied within the growth stages. The presence of S. triqueter could improve the activity of soil enzymes and facilitate the propagation of microorganisms which could help eliminate pyrene contamination.

Development of a home-based telehealthcare model for improving the effectiveness of the chronic care of stroke patients

This study describes the development of an information technology (IT)-mediated home-based healthcare model designed to improve the effectiveness of caring for stroke patients who require chronic, home care. This model was evaluated at Kaohsiung Medical Hospital in Taiwan between 2005 and 2008; 84 newly diagnosed stroke patients diagnosed as the chronic covalence stage were enrolled for preliminary testing of this model. These patients required 24-hour in-home monitoring of their health status and emergency call service. Over the course of the study, 15 emergency transfers were carried out, and the acute stroke patients were sent to the emergency care within 26 minutes, on average. This system helped physicians, patients, and their families to more efficiently detect the occurrence of recurrent stroke. In addition, we found a statistically significant finding (p < 0.001) that daily blood pressure (BP) monitoring increased from 45.5% in the initial month of the study to 76% after 3-10 months of intervention. Meanwhile, the proportion of patients with an abnormal BP rate decreased from 20.5% in the initial month of the study to 10.9% after 3-10 months of intervention. This suggests that this model helped to improve patient behavior and their ability to care for themselves. This is the first study to develop an IT-mediated, home-based healthcare model in Taiwan. This model integrates both healthcare and clinical services and is capable of enhancing the effectiveness of the care provided to patients with chronic diseases, especially those in situations where self-care is essential for disease management.

Prognostic significance of triple negative breast cancer at tumor size 1 cm and smaller

AIMS

The purpose of this study was to clarify the prognostic significance of triple-negative breast cancer (TNBC) with a tumor size ≤ 1 cm.

MATERIALS AND METHODS

Patients with primary operable breast cancer with a tumor size ≤ 1 cm were enrolled at Changhua Christian Hospital and National Cheng-Kung University Hospital. Tumors negative for ER, PR, and HER-2 were classified as TNBCs and compared with tumors with any receptor positivity (non-TNBC) for disease-free survival (DFS) and cancer-specific survival (CSS).

RESULTS

From 1995 to 2006, a total of 377 patients with tumor size ≤ 1 cm were enrolled. Compared with non-TNBC patients, TNBC patients with a tumor size ≤ 1 cm as a whole or in a lymph node-positive subgroup were not associated with a poorer 5-year DFS and CSS. In lymph node-negative patients (pT1a-bN0M0), TNBC was associated with a poorer 5-year CSS but not DFS. Compared with the hormone receptor-positive, HER-2-negative subgroup, TNBC was associated with poorer DFS and CSS. In the multivariate Cox regression hazard analysis, lymph node invasion was the most important cause of disease recurrence and cancer-specific death.

CONCLUSION

TNBC is very likely an independent risk factor in small (≤1 cm) node-negative invasive breast cancer. With tumors 1 cm and smaller, lymph node invasion was the single most important prognostic factor.

Risk perceptions and family history of lung cancer: differences by smoking status

BACKGROUND

Individuals with a family history of lung cancer have a two- to threefold increased risk for developing this disease. Family history information may be useful in lung cancer prevention and control approaches, but research is needed regarding how individuals interpret this information. This study examined associations between lung cancer family history and individuals' risk perceptions, based on smoking status.

METHODS

Data were analyzed from 5,105 U.S. adult respondents to the 2005 Health Information National Trends Survey, which was conducted with a nationally representative sample.

RESULTS

In multivariate models, family history of lung cancer was positively associated with absolute and relative risk perceptions among all respondents (β=0.60, 95% CI=0.33-0.87 and β=0.17, 95% CI=0.04-0.31, respectively) and among never smokers (β=0.40, 95% CI=0.14-0.67 and β=0.14, 95% CI=0.01-0.27, respectively). However, these associations were not significant for current and former smokers.

CONCLUSION

While perceived risk was associated with family history of lung cancer among never smokers, this was not true for other smoking status subgroups. Therefore, former and current smokers might not respond as intended to cancer prevention or cessation messages tailored based on family history. The results suggest directions for future research into how to best integrate family history information into prevention and control efforts.

A pre-paid newborn hearing screening programme: a community-based study

OBJECTIVES

To help obstetric hospitals and clinics to implement newborn hearing screening and to test the feasibility of a pre-paid model for screening.

PATIENTS AND METHODS

From July 2005 to August 2008, we organised a coordinated newborn hearing screening team with portable automated auditory brainstem response (AABR) to provide in-patient screening after delivery and out-patient re-screening at one month of age in birthing facilities throughout Changhua County, Taiwan. This was a community-based study organised by otolaryngologists at a tertiary referral centre.

RESULTS

Ten medical facilities participated in our screening programme. 7,139 out of 12,901 neonates delivered in these facilities during the period were screened for hearing loss. 105 (1.47%) babies who did not pass the in-patient screening were re-screened at one month old. Forty (0.56%) babies referred from the re-screening were sent for diagnostic work-up and six of them failed to show up. The overall follow-up rate was 94.3% (99/105). Eleven babies with bilateral hearing loss and eight babies with unilateral hearing loss were diagnosed. The incidence of bilateral hearing loss in our programme was 1.5/1000. The screening rate descended from medical centre to clinic (p < 0.0001). There was no significant difference between the referral rates for different levels of birthing facilities (p = 0.5611).

CONCLUSIONS

Our study demonstrates that a pre-paid model using AABR is feasible at all three levels of medical facilities. Pre-paid community-based screening might be an option for developing countries in the implementation of universal newborn hearing screening.

Study on milk-clotting mechanism of rennet-like enzyme from glutinous rice wine: proteolytic property and the cleavage site on kappa-casein

Chinese Royal cheese, an ancient and attractive dairy product now in China, is made from milk coagulated with glutinous rice wine. In this paper, it was mainly studied on the proteolytic property toward proteins of bovine milk including caseins (CN) and whey proteins and the cleavage bond on the kappa-CN of rennet-like enzyme purified from glutinous rice wine by ion-exchange chromatography. Compared with whey protein, the rennet-like protease has substrate specificity toward CN but with different hydrolysis degrees among kappa-, alpha-, and beta-CN, and the alpha-CN was almost completely degraded, whereas kappa- and beta-CN partly showed hydrolysis in 12 h. The analysis for enzyme digestion by electrospray tandem mass spectrometry, Q-TOF2, and matrix-assisted laser desorption-ionization time-of-flight mass spectrometry revealed that the cleavage of protease from glutinous rice wine on kappa-CN mainly happens at the Thr94-Met95 bond, which is different from the most chymosin-sensitive bond, Phe105-Met106.

The quadratic cumulative odds regression model for scored ordinal outcomes: application to alcohol dependence

In this paper, we develop new regression models for the analysis of scored ordinal data (i.e. ordinal outcomes where the categories are assigned numeric values). The novel feature of these models is that they enable one to capture and identify nonlinear aspects of the relationship between an ordinal clinical measurement (used for disease diagnosis) and risk factors. These nonlinearities may be useful in generating hypotheses about the risk factor's role in the etiologic process as well as suggesting how to design future studies of the risk factor. We apply our model to study the effects of race, gender, and family history on alcohol dependence among a cohort of lifetime drinkers from the 1992 National Longitudinal Alcohol Epidemiologic Survey.

Frataxin expression rescues mitochondrial dysfunctions in FRDA cells

Friedreich's ataxia (FRDA) is the result of mutations in the nuclear-encoded frataxin gene, which is expressed in mitochondria. Several lines of evidence have suggested that frataxin is involved in mitochondrial iron homeostasis. We have transfected the frataxin gene into lymphoblasts of FRDA compound heterozygotes (FRDA-CH) with deficient frataxin expression to produce FRDA-CH-t cells in which message and protein are rescued to near-physiological levels. FRDA-CH cells were more sensitive to oxidative stress by challenge with free iron, hydrogen peroxide and the combination, consistent with a Fenton chemical mechanism of pathophysiology, and this sensitivity was rescued to control levels in FRDA-CH-t cells. Iron challenge caused increased mitochondrial iron levels in FRDA-CH cells, and a decreased mitochondrial membrane potential (MMP), both of which were rescued in FRDA-CH-t cells. The rescue of the low MMP, and high mitochondrial iron concentration by frataxin overexpression suggests that these cellular phenotypes are relevant to the central pathophysiological process in FRDA which is aggravated by exposure to free iron. However, even at physiological iron concentrations, FRDA-CH cells had decreased MMP as well as lower activities of aconitase and ICDH (two enzymes supporting MMP), and twice the level of filtrable mitochondrial iron (but no increase in total mitochondrial iron), and the observed phenotypes were either fully or partially rescued in FRDA-CH-t cells. Free iron is known to be toxic. The observation that frataxin deficiency (either directly or indirectly) causes an increase in filtrable mitochondrial iron provides a new hypothesis for the mechanism of cell death in this disease, and could be a target for therapy.

Modulation of QT interval by cardiac sympathetic nerve sprouting and the mechanisms of ventricular arrhythmia in a canine model of sudden cardiac death

INTRODUCTION

We previously reported that there is a high incidence of sudden cardiac death (SCD) in dogs with myocardial infarction (MI), complete AV block (CAVB), and nerve growth factor (NGF) infusion to the left stellate ganglion (LSG). Whether or not QT interval prolongation underlines the mechanism of SCD was unclear.

METHODS AND RESULTS

We analyzed QT intervals in three groups of dogs. All dogs had CAVB and MI. The LSG group (n = 9) and right stellate ganglion (RSG) group (n = 6) received NGF infusion via the osmotic pumps over a 5-week period to LSG and RSG, respectively. The control group (n = 6) received no NGF. The dogs either died suddenly or were sacrificed within 2 to 3 months after MI. Heart rhythm and QT and RR intervals were monitored using implantable cardioverter defibrillator ECG recordings. There was a time-dependent increase of QTc intervals in the LSG group and a time-dependent decrease of QTc intervals in the RSG group. At the end of NGF infusion, QTc intervals in the LSG group (408 +/- 41 msec) were significantly longer than those in the control (350 +/- 41 msec; P < 0.05) and RSG groups (294 +/- 23 msec; P < 0.01). In the LSG group, 4 of 9 dogs died of SCD. There was no SCD in either the RSG or control group. Immunocytochemical staining showed NGF infusion to LSG and RSG resulted in left and right ventricular sympathetic nerve sprouting and hyperinnervation, respectively.

CONCLUSION

NGF infusion to the LSG in dogs with MI and CAVB resulted in increased QT interval and incidence of ventricular tachycardia, ventricular fibrillation, and SCD, whereas NGF infusion to the RSG shortened QT interval and reduced the incidence of ventricular tachycardia. These findings indicate that QT interval prolongation is causally related to the occurrence of ventricular arrhythmia in dogs with nerve sprouting, MI, and CAVB.

Disulfide bonds stabilize JC virus capsid-like structure by protecting calcium ions from chelation

To investigate the role of disulfide bonds in the capsid structure, a recombinant JC virus-like particle (VLP) was used. The major capsid protein, VP1, of the JC virus was expressed in yeast cells. The yeast-expressed VP1 was self-assembled into a VLP. Disulfide bonds were found in the VLP which caused dimeric and trimeric VP1 linkages as demonstrated by non-reducing SDS-PAGE. The VLP remained intact when disulfide bonds were reduced by dithiothreitol. The VLP without disulfide bonds could be disassembled into capsomeres by EGTA alone, but those with disulfide bonds could not be disassembled by EGTA. Capsomeres were reassembled into VLPs in the presence of calcium ions. Capsomeres formed irregular aggregations instead of VLPs when treated with diamide to reconstitute the disulfide bonds. These results indicate that disulfide bonds play an important role in maintaining the integrity of the JC VLP by protecting calcium ions from chelation.

[Expression and characterization of human pulmonary surfactant-associated protein A1 in Saccharomyces cerevisiae]

The cDNA encoding pulmonary surfactant-associated protein A1 (SP-A1) derived from healthy adult's lung was cloned into the pVT102U/alpha, expression vector of Saccharomyces cerevisiae, which contains the yeast alpha-factor signal sequence, leading to the secretion of expressed protein, and then transformed into Saccharomyces cerevisiae S-78 (leu2, ura3, rep4) by electroporation. After 2-3 days culture in adequate pH, the expressed SP-A1 accumulated up to 400 mg/L in supernatant. The pure proteins were obtained by Sephadex G-25, G-75, Sepharose 4B. The expressed recombinant products, 62 kD and 32 kD, reacted to specific antibody using ELISA and Western blot. The SP-A1 protein expressed in Saccharomyces cerevisiae was efficient in enhancing the phagocytosis of E. coli J5 by alveolar macrophages.

Sympathetic nerve sprouting, electrical remodeling and the mechanisms of sudden cardiac death

The purpose of this article is to review the nerve sprouting hypothesis of sudden cardiac death. It is known that sympathetic stimulation is important in the generation of sudden cardiac death. For example, there is a diurnal variation of sudden death rate in patients with myocardial infarction. Beta blockers, or drugs with beta blocking effects, are known to prevent sudden cardiac death. It was unclear if the cardiac nerves in the heart play only a passive role in the mechanisms of sudden death. To determine if nerve sprouting and neural remodeling occur after myocardial infarction, we performed immunocytochemical studies of cardiac nerves in explanted native hearts of transplant recipients. We found that there was a positive correlation between nerve density and a clinical history of ventricular arrhythmia. Encouraged by these results, we performed a study in dogs to determine whether or not nerve growth factor (NGF) infusion to the left stellate ganglion can facilitate the development of ventricular tachycardia (VT), ventricular fibrillation (VF), and sudden cardiac death (SCD). The results showed that augmented myocardial sympathetic nerve sprouting through NGF infusion plus atrioventricular (AV) block and MI result in a 44% incidence (four of nine dogs) of SCD and a high incidence of VT in the chronic phase of MI. In contrast, none of the six dogs (with AV block and MI) without NGF infusion died suddenly or had frequent VT episodes. Based on these findings, we propose the nerve sprouting hypothesis of ventricular arrhythmia and SCD. The hypothesis states that MI results in nerve injury, followed by sympathetic nerve sprouting and regional (heterogeneous) myocardial hyperinnervation. The coupling between augmented sympathetic nerve sprouting with electrically remodeled myocardium results in VT, VF and SCD. Modification of nerve sprouting after MI may provide a novel opportunity for arrhythmia control.

The murine amelogenin promoter: developmentally regulated expression in transgenic animals

We are interested in understanding hierarchical regulation pathways that control gene expression in developing teeth. In pursuit of the molecular basis for the regulated expression of amelogenin by developing ameloblasts during tooth formation, we isolated the murine amelogenin promoter. Analysis of this promoter will provide additional details towards the identification of signals generated through instructive-, dissimilar-germ layer interactions that are for responsible for temporal- and spatial-regulation for amelogenin gene expression. Using transgenic mice we demonstrate that a 2263 nucleotide stretch of the murine amelogenin promoter conveys appropriate temporal- and spatial-regulation for amelogenin gene expression in response to instructive-signals. These transgenic animals are useful reagents to further dissect signaling pathways responsible for regulated gene expression by terminally differentiated ameloblasts.

Transgene animal model for protein expression and accumulation into forming enamel

Understanding the cellular and molecular events that regulate the formation of enamel is a major driving force in efforts to characterize critical events during amelogenesis. It is anticipated that through such an understanding, improvements in prevention, diagnosis and treatment-intervention into heritable and acquired diseases of enamel could be achieved. While knowledge of the precise role of an enamel-specific protein in directing the formation of inorganic crystallites remains refractory, progress has been made with other aspects of amelogenesis that can be brought to bear on the subject. One such area of progress has been with the identification of an ameloblast-lineage specific amelogenin gene promoter. This promoter can be used to direct the expression of enamel-specific proteins, as well as the expression of proteins foreign to amelogenesis, into the enamel extracellular matrix where their effect on biomineralization can be ascertained in a prospective manner. The resulting enamel from such animals can be examined by morphologic and biochemical modalities in order to identify the effect of the transgene protein on enamel crystallite formation and subsequent biomineralization. This manuscript outlines such a strategy with the potential for enhancing our understanding of amelogenesis.

Nerve sprouting and sympathetic hyperinnervation in a canine model of atrial fibrillation produced by prolonged right atrial pacing

BACKGROUND

Long-term rapid atrial pacing may result in atrial fibrillation (AF) in dogs. Whether there is histological evidence for neural remodeling is unclear.

METHOD AND RESULTS

We performed rapid right atrial pacing in 6 dogs for 111+/-76 days to induce sustained AF. Tissues from 6 healthy dogs were used as controls. Immunocytochemical staining of cardiac nerves was performed using anti-growth-associated protein 43 (GAP43) and anti-tyrosine hydroxylase (TH) antibodies. In dogs with AF, the density of GAP43-positive and TH-positive nerves in the right atrium was 470+/-406 and 231+/-126 per mm(2), respectively, which was significantly (P:<0.001) higher than the nerve density in control tissues (25+/-32 and 88+/-40 per mm(2), respectively). The density of GAP43-positive and TH-positive nerves in the atrial septum was 317+/-36 and 155+/-85 per mm(2), respectively, and was significantly (P:<0.001) higher than the nerve density in control tissues (9+/-13 and 30+/-7 per mm(2), respectively). Similarly, the density of GAP43-positive and TH-positive nerves in the left atrium of dogs with AF was 119+/-61 and 91+/-40 per mm(2), respectively, which was significantly (P:<0.001) higher than the nerve density in control tissues (10+/-15 and 38+/-39 per mm(2), respectively). Furthermore, in dogs with AF, the right atrium had a significantly higher nerve density than the left atrium. Microscopic examinations revealed an inhomogeneous distribution of cardiac nerves within each sampling site.

CONCLUSIONS

Significant nerve sprouting and sympathetic hyperinnervation are present in a canine model of sustained AF produced by prolonged right atrial pacing. The magnitude of nerve sprouting and hyperinnervation was higher in the right atrium than in the left atrium.

Colocalization of tenascin and sympathetic nerves in a canine model of nerve sprouting and sudden cardiac death

INTRODUCTION

Sympathetic nerve sprouting after myocardial infarction (MI) may contribute significantly to the occurrence of ventricular arrhythmia and sudden cardiac death. Tenascin-X (TnX), a matrix protein known to be associated with nerve growth in central and peripheral nerves, also may play a role in cardiac nerve sprouting after MI.

METHODS AND RESULTS

Immunocytochemical staining techniques were used to identify nerves in 5-microm serial sections from 6 normal dogs and 11 dogs with MI. Among the dogs with MI, 4 also received nerve growth factor infusion to the left stellate ganglion. The time between MI to tissue harvest averaged 35.7 +/- 14.4 days. Tyrosine hydroxylase (TH) stain was used to identify sympathetic nerves, and growth-associated protein-43 (GAP-43) was used to identify growing nerves. Polyclonal antibody was obtained for use in identifying TnX. Nerves were evident in both the infarcted and noninfarcted areas. Many nerves were found around blood vessels. A total of 181 nerves in 69 slides were examined: 89 were from noninfarcted myocardium, 4 from infarct, 13 from infarct border zone, and 75 from perivascular regions. Except in normal dogs, all nerves stained positive for TH also stained positive for GAP-43, indicating sympathetic nerve sprouting after MI. In all dogs, the nerves that stained positive for TH also stained positive for TnX.

CONCLUSION

There is a colocalization of TnX, GAP-43, and TH in sprouted cardiac nerves. These results suggest that TnX is important not only in the existing normal myocardial nerve cells but also in cardiac sympathetic nerve sprouting after MI.

Genetic characterization of soybean rhizobia in Paraguay

The soybean is an exotic plant introduced in Paraguay in this century; commercial cropping expanded after the 1970s. Inoculation is practiced in just 15 to 20% of the cropping areas, but root nodulation occurs in most sites where soybeans grow. Little is known about rhizobial diversity in South America, and no study has been performed in Paraguay until this time. Therefore, in this study, the molecular characterization of 78 rhizobial isolates from soybean root nodules, collected under field conditions in 16 sites located in the two main producing states, Alto Paraná and Itapúa, was undertaken. A high level of genetic diversity was detected by an ERIC-REP-PCR analysis, with the majority of the isolates representing unique strains. Most of the 58 isolates characterized by slow growth and alkaline reactions in a medium containing mannitol as a carbon source were clustered with strains representative of the Bradyrhizobium japonicum and Bradyrhizobium elkanii species, and the 16S ribosomal DNA (rDNA) sequences of 5 of those isolates confirmed the species identities. However, slow growers were highly polymorphic in relation to the reference strains, including five carried in commercial inoculants in neighboring countries, thus indicating that the Paraguayan isolates might represent native bradyrhizobia. Twenty isolates highly polymorphic in the ERIC-REP-PCR profiles were characterized by fast growth and acid reactions in vitro, and two of them showed high 16S rDNA identities with Rhizobium genomic species Q. However, two other fast growers showed high 16S rDNA identity with Agrobacterium spp., and both of these strains established efficient symbioses with soybean plants.

Relationship between regional cardiac hyperinnervation and ventricular arrhythmia

BACKGROUND

Sympathetic nerve activity is known to be important in ventricular arrhythmogenesis, but there is little information on the relation between the distribution of cardiac sympathetic nerves and the occurrence of spontaneous ventricular arrhythmias in humans.

METHODS AND RESULTS

We studied 53 native hearts of transplant recipients, 5 hearts obtained at autopsy of patients who died of noncardiac causes, and 7 ventricular tissues that had been surgically resected from the origin of ventricular tachycardia. The history was reviewed to determine the presence (group 1A) or absence (group 1B) of spontaneous ventricular arrhythmias. Immunocytochemical staining for S100 protein, neurofilament protein, tyrosine hydroxylase, and protein gene product 9.5 was performed to study the distribution and the density of sympathetic nerves. The average left ventricular ejection fraction was 0.22+/-0.07. A total of 30 patients had documented ventricular arrhythmias, including ventricular tachycardia and sudden cardiac death. A regional increase in sympathetic nerves was observed around the diseased myocardium and blood vessels in all 30 hearts. The density of nerve fibers as determined morphometrically was significantly higher in group 1A patients (total nerve number 19.6+/-11.2/mm(2), total nerve length 3.3+/-3.0 mm/mm(2)) than in group 1B patients (total nerve number 13.5+/-6.1/mm(2), total nerve length 2.0+/-1.1 mm/mm(2), P<0. 05 and P<0.01, respectively).

CONCLUSIONS

There is an association between a history of spontaneous ventricular arrhythmia and an increased density of sympathetic nerves in patients with severe heart failure. These findings suggest that abnormally increased postinjury sympathetic nerve density may be in part responsible for the occurrence of ventricular arrhythmia and sudden cardiac death in these patients.