Microsatellite and flow cytometry analysis to help understand the origin of Dioscorea alata polyploids

BACKGROUND AND AIMS

Dioscorea alata is a polyploid species with a ploidy level ranging from diploid (2n = 2x = 40) to tetraploid (2n = 4x = 80). Ploidy increase is correlated with better agronomic performance. The lack of knowledge about the origin of D. alata spontaneous polyploids (triploids and tetraploids) limits the efficiency of polyploid breeding. The objective of the present study was to use flow cytometry and microsatellite markers to understand the origin of D. alata polyploids.

METHODS

Different progeny generated by intracytotype crosses (2x × 2x) and intercytotype crosses (2x × 4x and 3x × 2x) were analysed in order to understand endosperm incompatibility phenomena and gamete origins via the heterozygosity rate transmitted to progeny.

RESULTS

This work shows that in a 2x × 2x cross, triploids with viable seeds are obtained only via a phenomenon of diploid female non-gametic reduction. The study of the transmission of heterozygosity made it possible to exclude polyspermy and polyembryony as the mechanisms at the origin of triploids. The fact that no seedlings were obtained by a 3x × 2x cross made it possible to confirm the sterility of triploid females. Flow cytometry analyses carried out on the endosperm of seeds resulting from 2x × 4x crosses revealed endosperm incompatibility phenomena.

CONCLUSIONS

The major conclusion is that the polyploids of D. alata would have appeared through the formation of unreduced gametes. The triploid pool would have been built and diversified through the formation of 2n gametes in diploid females as the result of the non-viability of seeds resulting from the formation of 2n sperm and of the non-viability of intercytotype crosses. The tetraploids would have appeared through bilateral sexual polyploidization via the union of two unreduced gametes due to the sterility of triploids.

A semi-automated vascular access system for preclinical models

Murine models are used extensively in biological and translational research. For many of these studies it is necessary to access the vasculature for the injection of biologically active agents. Among the possible methods for accessing the mouse vasculature, tail vein injections are a routine but critical step for many experimental protocols. To perform successful tail vein injections, a high skill set and experience is required, leaving most scientists ill-suited to perform this task. This can lead to a high variability between injections, which can impact experimental results. To allow more scientists to perform tail vein injections and to decrease the variability between injections, a vascular access system (VAS) that semi-automatically inserts a needle into the tail vein of a mouse was developed. The VAS uses near infrared light, image processing techniques, computer controlled motors, and a pressure feedback system to insert the needle and to validate its proper placement within the vein. The VAS was tested by injecting a commonly used radiolabeled probe (FDG) into the tail veins of five mice. These mice were then imaged using micro-positron emission tomography to measure the percentage of the injected probe remaining in the tail. These studies showed that, on average, the VAS leaves 3.4% of the injected probe in the tail. With these preliminary results, the VAS system demonstrates the potential for improving the accuracy of tail vein injections in mice.

Caries increment and prediction from 12 to 18 years of age: A follow-up study

AIM

This was to determine the increment of caries from 12 to 18 years of age and to explore the possibility of predicting caries increment in this period based on the caries experience at age 12 years.

STUDY DESIGN

Prospective longitudinal survey.

METHODS

A sample of 12-year-old children (n =159) were examined in 1993 and 70% of them re-examined at 18 years of age. Bitewing radiographs were taken and a diagnostic system using five caries grades (D(1) to D D(5)) was used at both ages. Children at risk were defined as those who developed manifest caries lesions (D(3-5)FS) on approximal surfaces during the follow-up period. Possible predictors were analysed by calculation of sensitivity, specificity, efficiency of the test, proportion that tested positive and actual proportion of the population at risk.

RESULTS

The mean caries increment (D(1-5)MFS) from 12 to 18 years of age was 4.2 (SD +/- 9.1). The percentage of caries-free adolescents at 12 and 18 years of age was 10% and 1% respectively; 25% had either a reversal or no increment in caries experience while the D(1-5)MFS increased in 65% of the adolescents. Of the increment of manifest lesions (D(3-5)FS), 18% were located in incisors/canines, 40% in premolars, 26% in first molars and 16% in second molars. Premolars had the largest proportion of the approximal surfaces with manifest caries increment. The best predictors of children at risk of approximal caries increment (D(3-5)FS) were caries experience (D(1-5)FS) on the approximal surfaces of premolars and second molars at the age of 12 years. The individuals that developed four or more manifest lesions on approximal surfaces between 12 and 18 years were the easiest to predict (sensitivity + specificity = 175%).

CONCLUSIONS

There was a considerable increment of manifest caries lesions from 12 to 18 years of age in all tooth groups. The best predictors for increment of manifest caries on approximal surfaces during the age period were approximal caries in premolars and second molars at the age of 12 years.

Estimation of mating system parameters in an evolving gynodioecous population of cultivated sunflower (Helianthus annuus L.)

Cultivated plants have been molded by human-induced selection, including manipulations of the mating system in the twentieth century. How these manipulations have affected realized parameters of the mating system in freely evolving cultivated populations is of interest for optimizing the management of breeding populations, predicting the fate of escaped populations and providing material for experimental evolution studies. To produce modern varieties of sunflower (Helianthus annuus L.), self-incompatibility has been broken, recurrent generations of selfing have been performed and male sterility has been introduced. Populations deriving from hybrid-F1 varieties are gynodioecious because of the segregation of a nuclear restorer of male fertility. Using both phenotypic and genotypic data at 11 microsatellite loci, we analyzed the consanguinity status of plants of the first three generations of such a population and estimated parameters related to the mating system. We showed that the resource reallocation to seed in male-sterile individuals was not significant, that inbreeding depression on seed production averaged 15-20% and that cultivated sunflower had acquired a mixed-mating system, with ∼50% of selfing among the hermaphrodites. According to theoretical models, the female advantage and the inbreeding depression at the seed production stage were too low to allow the persistence of male sterility. We discuss our methods of parameter estimation and the potential of such study system in evolutionary biology.

An ultra low energy biomedical signal processing system operating at near-threshold

This paper presents a voltage-scalable digital signal processing system designed for the use in a wireless sensor node (WSN) for ambulatory monitoring of biomedical signals. To fulfill the requirements of ambulatory monitoring, power consumption, which directly translates to the WSN battery lifetime and size, must be kept as low as possible. The proposed processing platform is an event-driven system with resources to run applications with different degrees of complexity in an energy-aware way. The architecture uses effective system partitioning to enable duty cycling, single instruction multiple data (SIMD) instructions, power gating, voltage scaling, multiple clock domains, multiple voltage domains, and extensive clock gating. It provides an alternative processing platform where the power and performance can be scaled to adapt to the application need. A case study on a continuous wavelet transform (CWT)-based heart-beat detection shows that the platform not only preserves the sensitivity and positive predictivity of the algorithm but also achieves the lowest energy/sample for ElectroCardioGram (ECG) heart-beat detection publicly reported today.

Multimodality breast cancer screening in women with a familial or genetic predisposition

BACKGROUND

Women with a predisposition for breast cancer require a tailored screening program for early cancer detection. We evaluated the performance of mammography (MG), ultrasonography (US), and magnetic resonance imaging (MRI) screening in these women.

PATIENTS AND METHODS

In asymptomatic women either confirmed as BRCA1/2 carriers, or having a greater than 30% probability of being so as estimated by brcapro [Berry D, Parmigiani G. Duke SPORE (Specialized Program of Research Excellence) in Breast Cancer. 1999], we conducted a prospective comparative trial consisting of annual MRI and MG, and biannual US and clinical breast examination. All evaluations were done within 30 days of one another. For each screening round, imaging tests were independently interpreted by three radiologists.

RESULTS

The study enrolled 184 women, and 387 screening rounds were performed, detecting 12 cancers (9 infiltrating, 3 in situ), for an overall cancer yield of 6.5%. At diagnosis, 7 infiltrating cancers were smaller than 2 cm (T1); only 1 woman presented with axillary nodal metastases. All tumours were negative for the human epidermal growth factor receptor 2. Of the 12 cancers, MRI detected 10, and MG, 7; US did not identify any additional cancers. The overall recall rate after MRI was 21.8%, as compared with 11.4% for US and 16.1% for MG. Recall rates declined with successive screening rounds. In total, 45 biopsies were performed: 21 as a result of an US abnormality; 17, because of an MRI lesion; and 7, because of a MG anomaly.

INTERPRETATION

In high-risk women, MRI offers the best sensitivity for breast cancer screening. The combination of yearly MRI and MG reached a negative predictive value of 100%. The recall rate is greatest with MRI, but declines for all modalities with successive screening rounds.

Clinical trial: endoscopic evaluation of naproxen etemesil, a naproxen prodrug, vs. naproxen - a proof-of-concept, randomized, double-blind, active-comparator study

BACKGROUND

Nonsteroidal anti-inflammatory drugs are associated with upper gastrointestinal mucosal injury. Naproxen etemesil is a lipophilic, non-acidic, inactive prodrug of naproxen that is hydrolysed to pharmacologically active naproxen once absorbed. We hypothesized that with lesser topical exposure to naproxen from the prodrug, there would be reduced gastroduodenal mucosal injury compared with naproxen.

AIM

To compare the degree of endoscopic mucosal damage of naproxen etemesil vs. naproxen.

METHODS

This multicentre, randomized, double-blind, double-dummy trial compared oral naproxen etemesil 1200 mg twice daily (n = 61) with naproxen 500 mg twice daily (n = 59) for 7.5 days in 120 healthy subjects (45-70 years; mean 51 years; 58% female) with baseline total modified gastroduodenal Lanza score ≤ 2 (no erosions/ulcers) on endoscopy. The primary endpoint was mean total modified gastroduodenal Lanza score on day 7. A secondary endpoint was incidence of gastric ulcers.

RESULTS

The day 7 mean total modified gastroduodenal Lanza score was 2.8 ± 1.7 for naproxen etemesil vs. 3.5 ± 2.0 for naproxen (P = 0.03), and significantly fewer naproxen etemesil-treated subjects (3.3%) developed gastric ulcers compared with naproxen-treated subjects (15.8%) (P = 0.02).

CONCLUSION

In this first proof-of-concept study, naproxen etemesil was associated with significantly lower gastroduodenal mucosal injury compared with naproxen after 7 days of exposure (

CLINICAL TRIAL NUMBER

NCT00750243).

Infection with hepatitis C virus genotype 3--experience of a tertiary health care centre in south India

To analyse the response rate and the predictive values of virological, biochemical and histological factors on HCV antiviral therapy in HCV genotype 3 infected patients, we retrospectively studied 21 HCV genotype 3 infected patients, who underwent HCV antiviral therapy. Low (57%) sustained viral response (SVR) rate and significant association of SVR with normalization of alanine transaminase (ALT) levels were observed in our study. Absence of early viral response (EVR) showed high (80%) predictive value on SVR. Absence of EVR and normalisation of the ALT levels can predict the outcome of HCV antiviral therapy.

The periodontal health of Nepalese schoolchildren

OBJECTIVES

To report on the periodontal status of schoolchildren in urban and rural Nepal and to identify possible risk indicators of poor periodontal health.

DESIGN

Cross-sectional 'pathfinder' survey using the stratified cluster sampling technique included seven urban and nine rural sites representing the three geographic divisions and five political regions of Nepal. Second stage sampling involved the random selection of 25 schools (18 government and seven private).

SUBJECTS

Final study population consisted of three age groups: 5-6-years (n=1025), 12-13-years (n=1037) and 15-16-years (n=1053).

OUTCOME MEASURES

Periodontal data was collected using CPI based on WHO methodology and criteria by trained examiners. A structured questionnaire was administered to collect information on oral health behavior and socio-economic status.

RESULTS

A gradual decline in the mean number of healthy sextants was noted with an increase in age among the schoolchildren. Males and females within a specific school and area showed no statistical significant difference when assessed for differences in score 0 (healthy periodontium) among all age groups except for 15-16-year-olds studying in government-urban schools. Multivariate logistic regression analyses showed that children 5 to 6 years of age studying in government urban (Adjusted Odds Ratio = 1.5, 95% Confidence Interval = 1.1-2.1) and government rural schools (Adj OR = 2.8, 95% CI 1.9-4.1) were at higher risk of having periodontal conditions (CPI scores >0) when compared to those in private urban schools. The probability of poorer periodontal status increased for 12 to 13 (Adjusted OR = 1.9, 95% CI 1.3-2.9) and 15 to 16-year-old children (Adjusted OR = 1.7, 95% CI 1.1-2.5) who studied in government rural schools.

CONCLUSIONS

A steady increase in periodontal conditions was observed with increasing age. The main risk indicator for unhealthy periodontal status at 5-6 years was studying and residing in government rural and urban schools; while the indicator of unhealthy periodontal status for children 12 to 13 and 15 to 16 years of age was studying in rural government schools.