Evidence for high gene flow, nonrandom mating, and genetic bottlenecks of Ganoderma boninense infecting oil palm (Elaeis guineensis Jacq.) plantations in Malaysia and Indonesia.

Ganoderma boninense, the causal agent of basal stem rot (BSR) disease, has been recognized as a major economic threat to commercial plantings of oil palm (Elaeis guineensis Jacq.) in Southeast Asia, which supplies 86% of the world's palm oil. High genetic diversity and gene flow among regional populations of 417 G. boninense isolates collected from Sabah, Sarawak, and Peninsular Malaysia (Malaysia) and Sumatra (Indonesia) were demonstrated using 16 microsatellite loci. Three genetic clusters and different admixed populations of G. boninense across regions were detected, and they appeared to follow the spread of the fungus from the oldest (Peninsular Malaysia and Sumatra) to younger generations of oil palm plantings (Sabah and Sarawak). Low spatial genetic differentiation of G. boninense (FST = 0.05) among the sampling regions revealed geographically nonrestricted gene dispersal, but isolation by distance was still evident. Analysis of molecular variance (AMOVA) confirmed the little to no genetic differentiation among the pathogen populations and the three genetic clusters defined by STRUCTURE and minimum spanning network. Despite G. boninense being highly outcrossing and spread by sexual spores, linkage disequilibrium was detected in 7 of the 14 populations. Linkage disequilibrium indicated that the reproduction of the fungus was not entirely by random mating and genetic drift could be an important structuring factor. Furthermore, evidence of population bottleneck was indicated in the oldest oil palm plantations as detected in genetic clusters 2 and 3, which consisted mainly of Peninsular Malaysia and Sumatra isolates. The population bottleneck or founding event could have arisen from either new planting or replanting after the removal of large number of palm hosts. The present study also demonstrated that migration and nonrandom mating of G. boninense could be important for survival and adaptation to new palm hosts.

Genetic diversity and gene flow amongst admixed populations of Ganoderma boninense, causal agent of basal stem rot in African oil palm (Elaeis guineensis Jacq.) in Sarawak (Malaysia), Peninsular Malaysia, and Sumatra (Indonesia).

In 1911 and 1917, the first commercial plantings of African oil palm (Elaeis guineensis Jacq.) were made in Indonesia and Malaysia in Southeast Asia. In less than 15 years, basal stem rot (BSR) was reported in Malaysia. It took nearly another seven decades to identify the main causal agent of BSR as the fungus, Ganoderma boninense. Since then, research efforts have focused on understanding G. boninense disease epidemiology, biology, and etiology, but limited progress was made to characterize pathogen genetic diversity, spatial structure, pathogenicity, and virulence. This study describes pathogen variability, gene flow, population differentiation, and genetic structure of G. boninense in Sarawak (Malaysia), Peninsular Malaysia, and Sumatra (Indonesia) inferred by 16 highly polymorphic cDNA-SSR (simple sequence repeat) markers. Marker-inferred genotypic diversity indicated a high level of pathogen variability among individuals within a population and among different populations. This genetic variability is clearly the result of outcrossing between basidiospores to produce recombinant genotypes. Although our results indicated high gene flow among the populations, there was no significant genetic differentiation among G. boninense populations on a regional scale. It suggested that G. boninense genetic makeup is similar across a wide region. Furthermore, our results revealed the existence of three admixed genetic clusters of G. boninense associated with BSR-diseased oil palms sampled throughout Sarawak, Peninsular Malaysia, and Sumatra. We postulate that the population structure is likely a reflection of the high genetic variability of G. boninense populations. This, in turn, could be explained by highly successful outcrossing between basidiospores of G. boninense from Southeast Asia and introduced genetic sources from various regions of the world, as well as regional adaptation of various pathogen genotypes to different palm hosts. Pathogen variability and population structure could be employed to deduce the epidemiology of G. boninense, as well as the implications of plantation cultural practices on BSR disease control in different regions.

Atypical ductal hyperplasia of the breast diagnosed by ultrasonographically guided core needle biopsy.

PURPOSE: We analysed the ultrasonographic (US) features of atypical ductal hyperplasia (ADH) of the breast diagnosed by US-guided core needle biopsy (CNB) with the aim of identifying factors that affect the underestimation of ADH. MATERIALS AND METHODS: A total of 134 ADH lesions sampled by US-guided CNB were reviewed retrospectively. All lesions were evaluated for pattern, size, lesion characteristics and margins, and the corresponding surgical outcome or imaging follow-up was obtained. Each patient's clinical and radiological features were analysed to identify factors involved in ADH underestimation. RESULTS: The prevalence of malignancy in each pattern of lesions following surgical excision was 32/81 (40%) for solid masses, 14/31 (45%) for ductal patterns, 5/17 (29%) for complex cystic lesions and 2/5 (40%) for architectural distortions. Based on the results of surgical and US follow-up, none of the category 3 lesions was proven to be a malignancy. Malignancy was found in 17 (21%) of the 80 BI-RADS (Breast Imaging Reporting and Data System) category 4a lesions, 20 (74%) of the 27 category 4b lesions, 12 (92%) of the 13 category 4c lesions, and four (100%) of the four category 5 lesions. Lesions with a higher US assessment category, lacking circumscribed margins, or a mammographic finding of suspected malignancy were all significantly associated with underestimation (p < 0.05 for each). CONCLUSION: US is useful in evaluating ADH lesions and in clarifying the indication for biopsy of these lesions. Familiarity with the frequency associated with malignancy for each feature will improve the utility of US in the work-up of these breast abnormalities.

APACHE II score and primary liver cancer history had risk of hospital mortality in patients with pyogenic liver abscess.

BACKGROUND: The Acute Physiology and Chronic Health Evaluation II classification system has been extensively used for predicting the patient mortality in various diseases. However, its utilisation on the pyogenic liver abscess has not yet been well studied. AIMS: The purpose of this study was to validate this system on this high death rate disease. PATIENTS: A retrospective study was conducted to assess 314 patients with pyogenic liver abscesses admitted to tertiary medical centre in past 12 years. METHODS: The outcome measurement was the in-hospital mortality. A multiple logistic regression model was used to assess the association between mortality and Acute Physiology and Chronic Health Evaluation II score while controlling for the potential confounding factors. RESULTS: The overall in-hospital mortality was 8.3%. The mean Acute Physiology and Chronic Health Evaluation II score of the expired patients was higher (P<0.0001). The mortality rate increased rapidly when Acute Physiology and Chronic Health Evaluation II score >or=15. After controlling for the potential confounding factors, patient with high admission Acute Physiology and Chronic Health Evaluation II score >or=15 had a higher chance of in-hospital mortality (P<0.01). In addition, the primary liver cancer history is also a risk factor (P=0.03). CONCLUSIONS: The Acute Physiology and Chronic Health Evaluation II score and the primary liver cancer history predict the in-hospital mortality of the pyogenic liver abscess patient.