KẾT QUẢ NGHIÊN CỨU VỀ ĐỘNG LỰC TRẦM TÍCH LƠ LỬNG TRONG MÙA KHÔ TẠI VÙNG BIỂN VEN BỜ CỬA SÔNG HẬU

During the dry season (April 2014 and March 2015), the program of cooperation in science and technology between Vietnam and the United States and the independent project VAST-DLT.06/15-16 have conducted two surveys aiming to investigate deposition and sptial and temporal distribution of suspended sediment concentration under the domination by hydrodynamic processes such as wave, current, river flow. In addition, we also investigated the effect of tidal current in relationship with concentration of suspended sediment. Three 12-hour continuous monitoring stations of suspended sediment factors, water level and current are located on the topset at a depth of 8 m, the foreset at a depth of 15 m and the bottomset at a depth of 25 m, with a distance between the two stations about 3 km. In which, the concentrations of suspended sediment (SSCs) in the range of particle sizes from 1.25 μm to 250 μm and particle diameter are measured by LISST-25x (Suspended Sediment Sensor), water level, velocity and current direction are measured by the ADCP. Results of data analysis show that the distributions of particle diameter of suspended sediment over time on the topset, the foreset and the bottomset are different and do not change much under tidal phases. Meanwhile, the concentrations of suspended sediment (SSCs) correlate with velocity and fluctuate under tidal phases. Suspended sediment is deposited at tidal transition and reactivates when current velocities increase in flood and ebb tide phases. The survey data show that the increase of current velocity during flood tide phase causes re-suspension of bottom sediments and increases the concentration of suspended sediment. At flood tide phase corresponding to strong velocity, suspended sediment moves faster and vice versa at ebb tide phase, smaller current velocity makes the movement speed of suspended sediment slow.Trong mùa khô (tháng 4 năm 2014 và tháng 3 năm 2015), chương trình hợp tác khoa học và công nghệ giữa Việt Nam và Hoa Kỳ, và đề tài độc lập mã số VAST-ĐLT.06/15-16 đã thực hiện 2 chuyến khảo sát nhằm mục đích điều tra sự lắng đọng và phân bố theo không gian, thời gian của hàm lượng trầm tích lơ lửng dưới sự chi phối chủ yếu bởi các quá trình thủy động lực như sóng, dòng chảy, lưu lượng nước sông. Ngoài ra, chúng tôi còn khảo sát ảnh hưởng của dòng triều trong mối tương quan với hàm lượng trầm tích lơ lửng. Ba trạm đo liên tục trong 12 giờ các yếu tố trầm tích lơ lửng, mực nước và dòng chảy được đặt trên thềm châu thổ (topset) ở độ sâu 8 m, sườn châu thổ (foreset) ở độ sâu 15 m và chân châu thổ (bottomset) ở độ sâu 25 m, các trạm được đặt cách nhau 3 km. Trong đó, nồng độ trầm tích lơ lửng (SSCs) trong giới hạn kích thước hạt từ 1,25 µm đến 250 µm và đường kính hạt được đo bằng máy LISST-25X (Suspended Sediment Sensor), mực nước, vận tốc và hướng dòng chảy được đo bằng máy ADCP. Kết quả phân tích số liệu cho thấy phân bố đường kính hạt của trầm tích lơ lửng theo thời gian trên thềm châu thổ, sườn châu thổ, chân châu thổ là khác nhau và chúng không biến động nhiều theo pha triều. Trong khi đó, hàm lượng trầm tích lơ lửng (SSCs) tương quan với vận tốc dòng chảy và dao động theo pha triều. Trầm tích lơ lửng lắng đọng vào lúc thuỷ triều chuyển trạng thái (từ triều rút sang triều dâng hoặc ngược lại) và được tái hoạt động trở lại khi tốc độ dòng chảy tăng trong pha triều lên và pha triều xuống. Các số liệu khảo sát cho thấy rằng sự tăng của tốc độ dòng chảy trong pha triều lên đã gây ra sự tái lơ lửng của trầm tích đáy và làm tăng hàm lượng trầm tích lơ lửng. Tại các pha triều lên ứng với vận tốc dòng chảy lớn, trầm tích lơ lửng được dịch chuyển nhanh hơn và ngược lại tại pha triều xuống, tốc độ dòng chảy thấp hơn đã làm tốc độ dịch chuyển của trầm tích chậm lại

Rapidly and Slowly Growing Lineages in Chromosomal Instability-Type Gland-Forming Gastric Carcinomas as Revealed by Multisampling Analysis of DNA Copy-Number Profile.

BACKGROUND:To examine whether gastric carcinoma (GC) with chromosomal instability (CIN-type GC), the largest category in the Cancer Genome Atlas classification, consists of a single genetic lineage, we conducted a multisampling analysis of genomic DNA copy-number profile.METHODS:We performed array-based comparative genomic hybridization using formalin-fixed paraffin-embedded tissues from 54 gland-forming GCs containing a total of 106 DNA samples from mucosal, extramucosal invasive, and lymph node lesions. Microarray data were analyzed by unsupervised hierarchical clustering and penetrance plots. Epstein-Barr virus infection status and mismatch repair(MMR) enzyme-silencing/p53/mucin expression were examined by in situ hybridization and immunohistochemistry, respectively.RESULTS:The samples examined were divided into gain-rich cluster A and loss-rich cluster B, which were different in tumor locus and patient age. The T1/T2-4 ratio, the frequency of small cancers (diameter 2-4 cm), and intestinal mucin expression were higher in cluster B than in cluster A, but there were no significant differences in the frequencies of MMR silencing, mutant p53 pattern, and lymph node metastasis between the 2 clusters.CONCLUSIONS:We demonstrated that CIN-type GC could be categorized into 2 genetic lineages which are different in terms of rapidity of local extension but similar in terms of nodal metastasis risk

The Distribution of Incomplete Gastric Intestinal Metaplasia (GIM) Subtype among Biopsy Sites according to the Updated Sydney System and Its Association with GIM Extension

Background. Current guidelines recommend that extensive gastric intestinal metaplasia (GIM) be considered as a high-risk marker for the development of gastric cancer (GC). But there is emerging evidence that the incomplete GIM subtype is also a high-risk marker. Aims. To evaluate the performance of biopsy sites according to the updated Sydney system on detecting the incomplete GIM subtype and to assess its association with GIM extension. Patients and methods. A cross-sectional study was conducted on 280 Vietnamese patients with nonulcer dyspepsia. Biopsy specimens were taken from gastric sites according to the updated Sydney system, and sections were routinely stained with Giemsa and hematoxylin and eosin. Biopsy specimens with intestinalization were further evaluated for GIM subtypes with alcian blue 2.5 and periodic acid Schiff stainings. Two experienced pathologists jointly examined all the specimens and reached consensus. Results. The rates of patients with GIM and the incomplete GIM subtype were 81 (28.9%) and 24 (8.4%), respectively. There was no GIM in specimens taken from the greater curvature of corpus. The proportions of the incomplete GIM subtype detected at the incisura angularis, lesser curvature of corpus, lesser curvature of antrum, and greater curvature of antrum were 34.3% (12/35), 34.5% (10/29), 40.5% (17/42), and 31.6 (6/19), respectively, which were not significantly different (p=0.89). The presence of an incomplete GIM subtype was associated with multifocal GIM (i.e., ≥3 out of 5 biopsy sites with GIM) (OR=4.02, CI 95%, 1.33–12.16, p=0.022) and extensive GIM (i.e., GIM in specimens from both of corpus and antrum) (OR=2.89, CI 95% 1.04–8.02, p=0.045). Conclusions. The proportions of an incomplete GIM subtype were not significantly different among gastric biopsy sites with intestinalization. The association between an incomplete GIM subtype and GIM extension, therefore, may be due to an sum accumulation effect

Genetic landscape and personalized tracking of tumor mutations in Vietnamese women with breast cancer

Breast cancer is the leading cause of cancer death in Vietnamese women, but its mutational landscape and actionable alterations for targeted therapies remain unknown. After treatment, a sensitive biomarker to complement conventional imaging to monitor patients is also lacking. In this prospective multi‐center study, 134 early‐stage breast cancer patients eligible for curative‐intent surgery were recruited. Genomic DNA from tumor tissues and paired white blood cells were sequenced to profile all tumor‐derived mutations in 95 cancer‐associated genes. Our bioinformatic algorithm was then utilized to identify top mutations for individual patients. Serial plasma samples were collected before surgery and at scheduled visits after surgery. Personalized assay tracking the selected mutations were performed to detect circulating tumor DNA (ctDNA) in the plasma. We found that the mutational landscape of the Vietnamese was largely similar to other Asian cohorts, showing higher TP53 mutation frequency than in Caucasians. Alterations in PIK3CA and PI3K signaling were dominant, particularly in our triple‐negative subgroup. Using top‐ranked mutations, we detected ctDNA in pre‐operative plasma in 24.6–43.5% of the hormone‐receptor‐positive groups and 76.9–80.8% of the hormone‐receptor‐negative groups. The detection rate was associated with breast cancer subtypes and clinicopathological features that increased the risk of relapse. Interim analysis after a 15‐month follow‐up revealed post‐operative detection of ctDNA in all three patients that had recurrence, with a lead time of 7–13 months ahead of clinical diagnosis. Our personalized assay is streamlined and affordable with promising clinical utility in residual cancer surveillance. We also generated the first somatic variant dataset for Vietnamese breast cancer women that could lay the foundation for precision cancer medicine in Vietnam