Wheat stripe rust resistance locus YR63 is a hot spot for evolution of defence genes - a pangenome discovery

BACKGROUND

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), poses a threat to global wheat production. Deployment of widely effective resistance genes underpins management of this ongoing threat. This study focused on the mapping of stripe rust resistance gene YR63 from a Portuguese hexaploid wheat landrace AUS27955 of the Watkins Collection.

RESULTS

YR63 exhibits resistance to a broad spectrum of Pst races from Australia, Africa, Asia, Europe, Middle East and South America. It was mapped to the short arm of chromosome 7B, between two single nucleotide polymorphic (SNP) markers sunCS_YR63 and sunCS_67, positioned at 0.8 and 3.7 Mb, respectively, in the Chinese Spring genome assembly v2.1. We characterised YR63 locus using an integrated approach engaging targeted genotyping-by-sequencing (tGBS), mutagenesis, resistance gene enrichment and sequencing (MutRenSeq), RNA sequencing (RNASeq) and comparative genomic analysis with tetraploid (Zavitan and Svevo) and hexaploid (Chinese Spring) wheat genome references and 10+ hexaploid wheat genomes. YR63 is positioned at a hot spot enriched with multiple nucleotide-binding and leucine rich repeat (NLR) and kinase domain encoding genes, known widely for defence against pests and diseases in plants and animals. Detection of YR63 within these gene clusters is not possible through short-read sequencing due to high homology between members. However, using the sequence of a NLR member we were successful in detecting a closely linked SNP marker for YR63 and validated on a panel of Australian bread wheat, durum and triticale cultivars.

CONCLUSIONS

This study highlights YR63 as a valuable source for resistance against Pst in Australia and elsewhere. The closely linked SNP marker will facilitate rapid introgression of YR63 into elite cultivars through marker-assisted selection. The bottleneck of this study reinforces the necessity for a long-read sequencing such as PacBio or Oxford Nanopore based techniques for accurate detection of the underlying resistance gene when it is part of a large gene cluster.

Screening and social prescribing in healthcare and social services to address housing issues among children and families: a systematic review

OBJECTIVES

Housing is a social determinant of health that impacts the health and well-being of children and families. Screening and referral to address social determinants of health in clinical and social service settings has been proposed to support families with housing problems. This study aims to identify housing screening questions asked of families in healthcare and social services, determine validated screening tools and extract information about recommendations for action after screening for housing issues.

METHODS

The electronic databases MEDLINE, PsycINFO, EMBASE, Ovid Emcare, Scopus and CINAHL were searched from 2009 to 2021. Inclusion criteria were peer-reviewed literature that included questions about housing being asked of children or young people aged 0-18 years and their families accessing any healthcare or social service. We extracted data on the housing questions asked, source of housing questions, validity and descriptions of actions to address housing issues.

RESULTS

Forty-nine peer-reviewed papers met the inclusion criteria. The housing questions in social screening tools vary widely. There are no standard housing-related questions that clinical and social service providers ask families. Fourteen screening tools were validated. An action was embedded as part of social screening activities in 27 of 42 studies. Actions for identified housing problems included provision of a community-based or clinic-based resource guide, and social prescribing included referral to a social worker, care coordinator or care navigation service, community health worker, social service agency, referral to a housing and child welfare demonstration project or provided intensive case management and wraparound services.

CONCLUSION

This review provides a catalogue of housing questions that can be asked of families in the clinical and/or social service setting, and potential subsequent actions.

Physical separation of haplotypes in dikaryons allows benchmarking of phasing accuracy in Nanopore and HiFi assemblies with Hi-C data

Background

Most animals and plants have more than one set of chromosomes and package these haplotypes into a single nucleus within each cell. In contrast, many fungal species carry multiple haploid nuclei per cell. Rust fungi are such species with two nuclei (karyons) that contain a full set of haploid chromosomes each. The physical separation of haplotypes in dikaryons means that, unlike in diploids, Hi-C chromatin contacts between haplotypes are false-positive signals.

Results

We generate the first chromosome-scale, fully-phased assembly for the dikaryotic leaf rust fungus Puccinia triticina and compare Nanopore MinION and PacBio HiFi sequence-based assemblies. We show that false-positive Hi-C contacts between haplotypes are predominantly caused by phase switches rather than by collapsed regions or Hi-C read mis-mappings. We introduce a method for phasing of dikaryotic genomes into the two haplotypes using Hi-C contact graphs, including a phase switch correction step. In the HiFi assembly, relatively few phase switches occur, and these are predominantly located at haplotig boundaries and can be readily corrected. In contrast, phase switches are widespread throughout the Nanopore assembly. We show that haploid genome read coverage of 30–40 times using HiFi sequencing is required for phasing of the leaf rust genome, with 0.7% heterozygosity, and that HiFi sequencing resolves genomic regions with low heterozygosity that are otherwise collapsed in the Nanopore assembly.

Conclusions

This first Hi-C based phasing pipeline for dikaryons and comparison of long-read sequencing technologies will inform future genome assembly and haplotype phasing projects in other non-haploid organisms.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13059-022-02658-2.

The Canadian Neuromuscular Disease Registry 2010-2019: A Decade of Facilitating Clinical Research Througha Nationwide, Pan-NeuromuscularDisease Registry

We report the recruitment activities and outcomes of a multi-disease neuromuscular patient registry in Canada. The Canadian Neuromuscular Disease Registry (CNDR) registers individuals across Canada with a confirmed diagnosis of a neuromuscular disease. Diagnosis and contact information are collected across all diseases and detailed prospective data is collected for 5 specific diseases: Amyotrophic Lateral Sclerosis (ALS), Duchenne Muscular Dystrophy (DMD), Myotonic Dystrophy (DM), Limb Girdle Muscular Dystrophy (LGMD), and Spinal Muscular Atrophy (SMA). Since 2010, the CNDR has registered 4306 patients (1154 pediatric and 3148 adult) with 91 different neuromuscular diagnoses and has facilitated 125 projects (73 academic, 3 not-for-profit, 3 government, and 46 commercial) using registry data. In conclusion, the CNDR is an effective and productive pan-neuromuscular registry that has successfully facilitated a substantial number of studies over the past 10 years.

Geriatric assessment with management in cancer care: Current evidence and potential mechanisms for future research

Older adults with cancer represent a complex patient population. Geriatric assessment (GA) is recommended to evaluate the medical and supportive care needs of this group. "GA with management" is a term encompassing the resultant medical decisions and interventions implemented in response to vulnerabilities identified on GA. In older, non-cancer patients, GA with management has been shown to improve a variety of outcomes, such as reducing functional decline and health care utilization. However, the role of GA with management in the older adult with cancer is less well established. Rigorous clinical trials of GA with management are necessary to develop an evidence base and support its use in the routine oncology care of older adults. At the recent U-13 conference, "Design and Implementation of Intervention Studies to Improve or Maintain Quality of Survivorship in Older and/or Frail Adults with Cancer," a session was dedicated to developing research priorities in GA with management. Here we summarize identified knowledge gaps in GA with management studies for older patients with cancer and propose areas for future research.

Comorbidity in older adults with cancer

Comorbidity is an issue of growing importance due to changing demographics and the increasing number of adults over the age of 65 with cancer. The best approach to the clinical management and decision-making in older adults with comorbid conditions remains unclear. In May 2015, the Cancer and Aging Research Group, in collaboration with the National Cancer Institute and the National Institute on Aging, met to discuss the design and implementation of intervention studies in older adults with cancer. A presentation and discussion on comorbidity measurement, interventions, and future research was included. In this article, we discuss the relevance of comorbidities in cancer, examine the commonly used tools to measure comorbidity, and discuss the future direction of comorbidity research. Incorporating standardized comorbidity measurement, relaxing clinical trial eligibility criteria, and utilizing novel trial designs are critical to developing a larger and more generalizable evidence base to guide the management of these patients. Creating or adapting comorbidity management strategies for use in older adults with cancer is necessary to define optimal care for this growing population.

Internet cognitive behavioural therapy for mixed anxiety and depression: a randomized controlled trial and evidence of effectiveness in primary care

BACKGROUND

Major depressive disorder (MDD) and generalized anxiety disorder (GAD) have the highest co-morbidity rates within the internalizing disorders cluster, yet no Internet-based cognitive behavioural therapy (iCBT) programme exists for their combined treatment.

METHOD

We designed a six-lesson therapist-assisted iCBT programme for mixed anxiety and depression. Study 1 was a randomized controlled trial (RCT) comparing the iCBT programme (n = 46) versus wait-list control (WLC; n = 53) for patients diagnosed by structured clinical interview with MDD, GAD or co-morbid GAD/MDD. Primary outcome measures were the Patient Health Questionnaire nine-item scale (depression), Generalized Anxiety Disorder seven-item scale (generalized anxiety), Kessler 10-item Psychological Distress scale (distress) and 12-item World Health Organization Disability Assessment Schedule II (disability). The iCBT group was followed up at 3 months post-treatment. In study 2, we investigated the adherence to, and efficacy of the same programme in a primary care setting, where patients (n = 136) completed the programme under the supervision of primary care clinicians.

RESULTS

The RCT showed that the iCBT programme was more effective than WLC, with large within- and between-groups effect sizes found (>0.8). Adherence was also high (89%), and gains were maintained at 3-month follow-up. In study 2 in primary care, adherence to the iCBT programme was low (41%), yet effect sizes were large (>0.8). Of the non-completers, 30% experienced benefit.

CONCLUSIONS

Together, the results show that iCBT is effective and adherence is high in research settings, but there is a problem of adherence when translated into the 'real world'. Future efforts need to be placed on developing improved adherence to iCBT in primary care settings.

Validation of simulation of calcifications for observer studies in digital mammography

Studies using simulated calcifications can be performed to measure the effect of different imaging factors on calcification detection in digital mammography. The simulated calcifications must be inserted into clinical images with realistic contrast and sharpness. MoCa is a program which modifies the contrast and sharpness of simulated calcification clusters extracted from images of mastectomy specimens acquired on a digital specimen cabinet at high magnification for insertion into clinical mammography images. This work determines whether the use of MoCa results in simulated calcifications with the correct contrast and sharpness. Aluminium foils (thickness 0.1-0.4 mm) and 1.60 µm thick gold discs (diameter 0.13-0.8 mm) on 0.5 mm aluminium were imaged with a range of thicknesses of polymethyl methacrylate (PMMA) using an amorphous selenium direct digital (DR) system and a powder phosphor computed radiography (CR) system (real images). Simulated images of the tests objects were also generated using MoCa. The contrast of the aluminium squares and the degradation of the contrast of the gold discs as a function of disc diameter were compared in the real and simulated images. The average ratios of the simulated-to-real aluminium contrasts over all aluminium and PMMA thicknesses were 1.03 ± 0.04 (two standard errors in the mean) and 0.99 ± 0.03 for the DR and CR systems, respectively. The ratio of the simulated-to-real degradations of contrast averaged over all disc diameters and PMMA thicknesses were 1.007 ± 0.008 and 1.002 ± 0.013 for DR and CR, respectively. The use of MoCa was accurate within the experimental errors.

Comparison of the x-ray attenuation properties of breast calcifications, aluminium, hydroxyapatite and calcium oxalate

Aluminium is often used as a substitute material for calcifications in phantom measurements in mammography. Additionally, calcium oxalate, hydroxyapatite and aluminium are used in simulation studies. This assumes that these materials have similar attenuation properties to calcification, and this assumption is examined in this work. Sliced mastectomy samples containing calcification were imaged at ×5 magnification using a digital specimen cabinet. Images of the individual calcifications were extracted, and the diameter and contrast of each calculated. The thicknesses of aluminium required to achieve the same contrast as each calcification when imaged under the same conditions were calculated using measurements of the contrast of aluminium foils. As hydroxyapatite and calcium oxalate are also used to simulate calcifications, the equivalent aluminium thicknesses of these materials were also calculated using tabulated attenuation coefficients. On average the equivalent aluminium thickness was 0.85 times the calcification diameter. For calcium oxalate and hydroxyapatite, the equivalent aluminium thicknesses were 1.01 and 2.19 times the thickness of these materials respectively. Aluminium and calcium oxalate are suitable substitute materials for calcifications. Hydroxyapatite is much more attenuating than the calcifications and aluminium. Using solid hydroxyapatite as a substitute for calcification of the same size would lead to excessive contrast in the mammographic image.

Purification and Characterization of a Population of EGFP-Expressing Cells from the Developing Pancreas of a Neurogenin3/EGFP Transgenic Mouse

Neurogenin 3 (ngn3) is a basic helix loop helix transcription factor that is transiently expressed in the developing mouse pancreas with peak expression around E15. In mice lacking the ngn3 gene the endocrine cells of the pancreas fail to develop suggesting that the ngn3-positive cell may represent a progenitor cell for the endocrine pancreas. In order to purify and characterize this cell in detail we have generated a transgenic mouse, in which the ngn3 promoter drives expression of enhanced green fluorescent protein (EGFP). In the E15.5 embryo EGFP was expressed in the dorsal and ventral pancreas, the duodenum, and lower intestine as well as in the brain. This pattern of expression was in keeping with the known expression profile of the endogenous ngn3 gene. Within the pancreas EGFP was localized in close proximity to cells that stained positive for ngn3, insulin, and glucagon, but was absent from regions of the pancreas that stained positive for amylase. EGFP was also present in the pancreas at E18.5, although there was no detectable expression of ngn3. At this stage EGFP did not colocalize with any of the hormones or exocrine markers. EGFP(+) cells were FACS purified (96%) from the E15 pancreas yielding approximately 10,000 cells or 1.6% of the total pancreatic cells from one litter. RT/PCR analysis confirmed that the purified cells expressed EGFP, ngn3, insulin, glucagon, somatostatin and pancreatic polypeptide. The ability to purify ngn3(+) cells provides an invaluable source of material for charactering in detail their properties.

Quality control measurements for digital x-ray detectors

This paper describes a digital radiography (DR) quality control protocol for DR detectors from the forthcoming report from the Institute of Physics and Engineering in Medicine (IPEM). The protocol was applied to a group of six identical caesium iodide (CsI) digital x-ray detectors to assess reproducibility of methods, while four further detectors were assessed to examine the wider applicability. Twelve images with minimal spatial frequency processing are required, from which the detector response, lag, modulation transfer function (MTF), normalized noise power spectrum (NNPS) and threshold contrast-detail (c-d) detectability are calculated. The x-ray spectrum used was 70 kV and 1 mm added copper filtration, with a target detector air kerma of 2.5 µGy for the NNPS and c-d results. In order to compare detector performance with previous imaging technology, c-d data from four screen/film systems were also acquired, at a target optical density of 1.5 and an average detector air kerma of 2.56 µGy. The DR detector images were typically acquired in 20 min, with a further 45 min required for image transfer and analysis. The average spatial frequency for the 50% point of the MTF for six identical detectors was 1.29 mm(-1) ± 0.05 (3.9% coefficient of variation (cov)). The air kerma set for the six systems was 2.57 µGy ± 0.13 (5.0% cov) and the NNPS at this air kerma was 1.42 × 10(-5) mm(2) (6.5% cov). The detective quantum efficiency (DQE) measured for the six identical detectors was 0.60 at 0.5 mm(-1), with a maximum cov of 10% at 2.9 mm(-1), while the average DQE was 0.56 at 0.5 mm(-1) for three CsI detectors from three different manufacturers. Comparable c-d performance was found for these detectors (5.9% cov) with an average threshold contrast of 0.46% for 11 mm circular discs. The average threshold contrast for the S/F systems was 0.70% at 11 mm, indicating superior imaging performance for the digital systems. The protocol was found to be quick, reproducible and gave an in-depth assessment of performance for a range of digital x-ray detectors.

Controversies in communication of genetic risk for hereditary breast cancer

Increased availability and heightened consumer awareness of "cancer genes" has increased consumer interest in, and demand for breast cancer risk assessment, and thus a pressing need for providers to identify effective, efficient methods of communicating complicated genetic information to consumers and their potentially at-risk relatives. With increasing direct-to-consumer and -physician marketing of predictive genetic tests, there has been considerable growth in web- and telephone-based genetic services. There is urgent need to further evaluate the psychosocial and behavioral outcomes (i.e., risks and benefits) of telephone and web-based methods of delivery before they become fully incorporated into clinical care models. Given the implications of genetic test results for family members, and the inherent conflicts in health care providers' dual responsibilities to protect patient privacy and to "warn" those at-risk, new models for communicating risk to at-risk relatives are emerging. Additional controversies arise when the at-risk relative is a minor. Research evaluating the impact of communicating genetic risk to offspring is necessary to inform optimal communication of genetic risk for breast cancer across the lifespan. Better understanding the risks and benefits associated with each of these controversial areas in cancer risk communication are crucial to optimizing adherence to recommended breast cancer risk management strategies and ensuring psycho-social well-being in the clinical delivery of genetic services for breast cancer susceptibility.

Preoperative hypnotherapy in the management of a child with anticipatory nausea and vomiting

A six-year-old boy with oesophageal strictures secondary to neonatal repair of oesophageal atresia and requiring six to eight weekly oesophageal dilatations by bouginage developed anticipatory nausea and vomiting. This was effectively managed by a course of preoperative hypnotherapy over four sessions. Resolution of anticipatory nausea and vomiting occurred along with cessation of postoperative nausea and vomiting. This case supports early intervention with preoperative hypnotherapy in children with anticipatory nausea and vomiting that has not responded to other measures.

Practice MRI: reducing the need for sedation and general anaesthesia in children undergoing MRI

The aim of this study was to evaluate the effectiveness of a practice magnetic resonance unit, in preparing children to undergo magnetic resonance procedures without general anaesthesia (GA) or sedation. The records of children who attended the practice MRI between February 2002 and April 2004 were retrospectively reviewed. Each record was assessed as to whether the child had passed or failed the practice MRI intervention. Those children who were considered to have passed and were proceeded to a clinical non-GA MRI had the report of the clinical scan reviewed. If the scan had been reported as non-diagnostic because of movement artefact it was classified as a failed scan, otherwise it was considered a pass. One hundred and thirty-four children undertook a practice MRI (age range 4.1-16.1 years, median age 7.7 years, 47% boys) and 120/134 (90%) passed the practice session. In all, 117/120 (98%) subsequently had a clinical non-GA MRI and 110/117 (94%) passed (median age 7.8 years, 47% boys). Preparation is a safe and effective method to reduce the need for sedation and GA in children undergoing a clinical MRI scan. It provides a positive medical experience for children, parents and staff, and results in cost savings for the hospital.

A remote and highly conserved enhancer supports amygdala specific expression of the gene encoding the anxiogenic neuropeptide substance-P

The neuropeptide substance P (SP), encoded by the preprotachykinin-A (PPTA) gene, is expressed in the central and medial amygdaloid nucleus, where it plays a critical role in modulating fear and anxiety related behaviour. Determining the regulatory systems that support PPTA expression in the amygdala may provide important insights into the causes of depression and anxiety related disorders and will provide avenues for the development of novel therapies. In order to identify the tissue specific regulatory element responsible for supporting expression of the PPTA gene in the amygdala, we used long-range comparative genomics in combination with transgenic analysis and immunohistochemistry. By comparing human and chicken genomes, it was possible to detect and characterise a highly conserved long-range enhancer that supported tissue specific expression in SP expressing cells of the medial and central amygdaloid bodies (ECR1; 158.5 kb 5' of human PPTA ORF). Further bioinformatic analysis using the TRANSFAC database indicated that the ECR1 element contained multiple and highly conserved consensus binding sequences of transcription factors (TFs) such as MEIS1. The results of immunohistochemical analysis of transgenic lines were consistent with the hypothesis that the MEIS1 TF interacts with and maintains ECR1 activity in the central amygdala in vivo. The discovery of ECR1 and the in vivo functional relationship with MEIS1 inferred by our studies suggests a mechanism to the regulatory systems that control PPTA expression in the amygdala. Uncovering these mechanisms may play an important role in the future development of tissue specific therapies for the treatment of anxiety and depression.

Investigation of optimum energies for chest imaging using film-screen and computed radiography

The purpose of the study was to compare the image quality of film-screen (FS) and computed radiography (CR) for adult chest examinations across a range of beam energies. A series of images of the CDRAD threshold contrast detail detection phantom were acquired for a range of tube potential and exposure levels with both CR and FS. The phantom was placed within 9 cm of Perspex to provide attenuation and realistic levels of scatter in the image. Hardcopy images of the phantom were scored from a masked light-box by two scorers. Threshold contrast indices were used to calculate a visibility index (VI). The relationships between dose and image quality for CR and for FS are fundamentally different. The improvements in VIs obtained using CR at 75 kVp and 90 kVp were found to be statistically significant compared with 125 kVp at matched effective dose levels. The relative performance of FS and CR varies as a function of energy owing to the different k-edges of each system. When changing from FS to CR, the use of lower tube potentials may allow image quality to be maintained whilst reducing effective dose. A tube voltage of 90 kVp is indicated by this work, but may require clinical verification.

Chest radiography: a comparison of image quality and effective dose using four digital systems

Image quality (IQ) and effective dose for chest radiography was compared for four digital imaging systems that used three different detector technologies: a-Si/TFT flat-panel detector (FPD), scanning-slot/charge-coupled device (CCD) and photostimuable phosphor (PSP). On each system a phantom was exposed at 125 kV(p) for automatic exposure control (AEC) and 2, 4 and 8 Gy receptor dose using identical geometrical conditions. All images were scored as softcopy images by three observers. The effective dose was calculated for each exposure condition. For AEC, superior IQ was observed for the GE FPD compared with all the other systems, which showed similar IQ performance. For all systems the entrance surface dose associated with AEC was within the European recommendations but variations in the effective dose were observed between the four systems. For identical receptor dose levels superior IQ was observed with the FPDs. Thorascan was noted for its low effective dose and Agfa CR was associated with the highest effective dose. FPD systems showed a better overall performance, followed by the CCD and PSP systems.

Threshold contrast detail detectability curves for fluoroscopy and digital acquisition using modern image intensifier systems

Threshold contrast detail detectability (TCDD) test objects are a commonly used tool to assess image quality of imaging systems. FAXIL (The Facility for the Assessment of X-ray imaging, Leeds) produced updated standard TCDD curves, for fluoroscopy systems in good adjustment, in 1992. Fluoroscopy curves can be corrected to account for the effect of image intensifier input air kerma rate and field size. This paper presents updated TCDD curves for fluoroscopy and new curves for digital acquisition. The results for digital acquisition suggest that the TCDD curves should not be corrected for input air kerma, as the quantum noise is not dominant and system noise is significant. These curves will prove useful for accepting new equipment, to give an indication of the expected image quality for a new image intensifier system.

Intracranial pressure measurement, induced hypothermia and barbiturate coma in meningitis associated with intractable raised intracranial pressure

We report the use of intracranial pressure monitoring, mild hypothermia and barbiturate coma in a patient with meningococcal meningitis complicated by raised intracranial pressure.

Use of a quality index in threshold contrast detail detection measurements in television fluoroscopy

The use of a single index to assist in quality control procedures of X-ray television fluoroscopy systems was investigated. A single quality index was devised incorporating a measure of threshold contrast detail detectability (TCDD) performance and taking into account image intensifier input kerma rate, field size, differences in radiation beam quality, and pulsed fluoroscopy. This was applied to a number of clinical systems to investigate changes in image quality index quantified over time. Accepted measurement protocols were used to obtain these measurements. The results show system performance for different systems and can establish the decline in performance parameters over time or assess non-optimal image quality with clinical systems in field measurements. The systems studied were assessed with a variety of performance parameters including TCDD results, low contrast sensitivity, limiting resolution, and image intensifier input kerma rate under clinical modes of operation. The TCDD quality index, and dose normalized quality index, were found to be useful image quality assessment parameters for serial testing of systems, which augment the use of graphical methods for the display of TCDD curves.

Tachykinin expression in cartilage and function in human articular chondrocyte mechanotransduction

OBJECTIVE

To assess whether substance P and the corresponding neurokinin 1 (NK1) receptor are expressed in human articular cartilage, and whether these molecules have a role in chondrocyte mechanotransduction.

METHODS

Transgenic studies, immunohistochemistry, Western blotting, and reverse transcriptase-polymerase chain reaction were used to assess the expression of the preprotachykinin (PPT) gene, substance P, and NK1 in developing mice, in adult human articular cartilage, and in human chondrocytes in culture. Chondrocytes obtained from PPT knockout mice and human articular chondrocytes were mechanically stimulated in the presence or absence of inhibitors of substance P signaling, and cell membrane potentials or relative levels of aggrecan messenger RNA (mRNA) were measured.

RESULTS

Replacing a region of the PPT gene transcriptional site that contains a dominant repressor of the proximal promoter activity with the constitutive minimal promoter of the human beta-globin promoter allowed expression of a marker gene in areas of chondrogenesis during mouse development and in adult chondrocytes grown in culture. Adult human articular chondrocytes expressed endogenous PPT mRNA, substance P, and the corresponding NK1 receptor in vivo and in vitro. Blockade of substance P signaling by a chemical antagonist to the NK1 receptor inhibited chondrocyte responses to mechanical stimulation.

CONCLUSION

Substance P is expressed in human articular cartilage and is involved in chondrocyte mechanotransduction via the NK1 receptor in an autocrine and paracrine manner. This suggests that substance P and the NK1 receptor have roles in the maintenance of articular cartilage structure and function that were previously unrecognized.

Transmission of hepatitis C in a pharmacologic study

OBJECTIVE

To describe an outbreak of hepatitis C in a clinical research study.

DESIGN

Observational study.

SETTING

Tertiary-care hospital.

PATIENTS

Healthcare workers who volunteered to be subjects in a study of the metabolic effects of inhaled and oral corticosteroids who were unwittingly exposed to hepatitis C virus (HCV).

METHODS

Epidemiological investigation and serological analyses.

RESULTS

One chronic carrier of HCV was identified. Four fellow workers volunteering in the studies became infected with HCV, with 96% homology among strains. There was no evidence of spread from infected healthcare workers to patients on whom they had performed arterial punctures (2 of 214 positive, unrelated to each other and to the outbreak strain).

CONCLUSION

Infection control standards in clinical research must be maintained vigorously to prevent transmission of blood-borne pathogens such as HCV.

Genetic composition and complexity of virus populations at tungro-endemic and outbreak rice sites

We have recently demonstrated the geographic isolation of rice tungro bacilliform virus (RTBV) populations in the tungro-endemic provinces of Isabela and North Cotabato, Philippines. In this study, we examined the genetic structure of the virus populations at the tungro-outbreak sites of Lanao del Norte, a province adjacent to North Cotabato. We also analyzed the virus populations at the tungro-endemic sites of Subang, Indonesia, and Dien Khanh, Vietnam. Total DNA extracts from 274 isolates were digested with EcoRV restriction enzyme and hybridized with a full-length probe of RTBV. In the total population, 22 EcoRV-restricted genome profiles (genotypes) were identified. Although overlapping genotypes could be observed, the outbreak sites of Lanao del Norte had a genotype combination distinct from that of Subang or Dien Khanh but a genotype combination similar to that identified earlier from North Cotabato, the adjacent endemic province. Sequence analysis of the intergenic region and part of the ORF1 RTBV genome from randomly selected genotypes confirms the geographic clustering of RTBV genotypes and, combined with restriction analysis, the results suggest a fragmented spatial distribution of RTBV local populations in the three countries. Because RTBV depends on rice tungro spherical virus (RTSV) for transmission, the population dynamics of both tungro viruses were then examined at the endemic and outbreak sites within the Philippines. The RTBV genotypes and the coat protein RTSV genotypes were used as indicators for virus diversity. A shift in population structure of both viruses was observed at the outbreak sites with a reduced RTBV but increased RTSV gene diversity.