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Higher Risks of Copper Toxicity in Turbid Waters: Quantifying the Bioavailability of Particle-Bound Metals to Set Site-Specific Water Quality Criteria

Cao X, Yu ZX, Xie M, Pan K, Tan QG

Environ Sci Technol, 2023 Jan 17;57(2):1060-1070.
PMID: 36595456 DOI: 10.1021/acs.est.2c06447

In coastal waters, particulate metals constitute a substantial fraction of the total metals; however, the prevalent water quality criteria are primarily based on dissolved metals, seemingly neglecting the contribution of particulate metals. Here we developed a method to quantify the toxicity risk of particulate metals, and proposed a way to calculate modifying factors (MFs) for setting site-specific criteria in turbid waters. Specifically, we used a side-by-side experimental design to study copper (Cu) bioaccumulation and toxicity in an estuarine clam, Potamocorbula laevis, under the exposure to "dissolved only" and "dissolved + particulate" 65Cu. A toxicokinetic-toxicodynamic model (TK-TD) was used to quantify the processes of Cu uptake, ingestion, assimilation, egestion, and elimination, and to relate mortality risk to tissue Cu. We find that particulate Cu contributes 40-67% of the Cu bioaccumulation when the suspended particulate matter (SPM) ranges from 12 to 229 mg L-1. The Cu-bearing SPM also increases the sensitivity of organisms to internalized Cu by decreasing the internal threshold concentration (CIT) from 141 to 76.8 μg g-1. MFs were derived based on the TK-TD model to consider the contribution of particulate Cu (in the studied SPM range) for increasing Cu bioaccumulation (MF = 1.3-2.2) and toxicity (MF = 2.3-3.9). Water quality criteria derived from dissolved metal exposure need to be lowered by dividing by an MF to provide adequate protection. Overall, the method we developed provides a scientifically sound framework to manage the risks of metals in turbid waters.
Fulltext Intraosseous synovial sarcoma of the proximal femur: Case report

Zulkarnaen M, Pan K, Shanmugam P, Ibrahim Z, Chan W

Malays Orthop J, 2012 Mar;6(1):49-52.
PMID: 25279044 MyJurnal DOI: 10.5704/MOJ.1203.003

ABSTRACT: Synovial sarcoma is primarily a soft tissue malignancy that most often affects adolescents and young adults. It very rarely presents as a primary bone tumour and has only been reported in nine other cases to date. We report a case of primary synovial sarcoma arising from the proximal femur in a 57-year-old man.
KEY WORDS: Synovial sarcoma, primary bone tumour.
Fulltext Methods used for reconstruction in aggressive bone tumours: an early experience

Pan KL, Ting SS, Mohamad AWK, Lee WG, Wong CC, Rasit AH

Med J Malaysia, 2003 Dec;58(5):752-7.
PMID: 15190663

Improvements in the overall treatment of patients with aggressive, large tumours involving the bone have made it possible to preserve and salvage limbs instead of amputating them. Each patient is unique in his clinical presentation and social circumstance. The different reconstructive options available allow us to choose the most appropriate method suited to the particular patient and with minimal delay, even when resources are limited. The patient and the relatives actively participate in the choice. The early experience of the different techniques for reconstructing these bone defects at our hospital are presented in this paper.
Fulltext Cryptococcal osteomyelitis of the femur: a case report and review of literature

Zainal AI, Wong SL, Pan KL, Wong OL, Tzar MN

Trop Biomed, 2011 Aug;28(2):444-9.
PMID: 22041767 MyJurnal

Fungal osteomyelitis is a rare opportunistic infection. It exhibits some clinical and radiological similarities to several other bone pathologies. A diagnostic delay may result in significant increase in morbidity. We report a case of a 37-year-old man with underlying hypogammaglobulinaemia presented with isolated cryptococcal osteomyelitis of the femur.
Expression pattern of AGPATs isoforms indicate different functions during the triacylglyceride synthesis in Chinese mitten crab, Eriocheir sinensis

Pan K, Zhu B, Wang L, Guo Q, Shu-Chien AC, Wu X

Comp Biochem Physiol A Mol Integr Physiol, 2024 Jan;287:111535.
PMID: 37852318 DOI: 10.1016/j.cbpa.2023.111535

The 1-acylglycerol-3-phosphate acyltransferase (AGPAT) acts as a crucial enzyme in the process of triacylglycerol (TAG) synthesis, enabling the acylation of lysophosphatidic acid (LPA) into phosphatidic acid (PA). In order to decode the distinctive roles of AGPAT isoforms in the TAG production pathway, three AGPAT isoforms were detected for the first time in the Chinese mitten crab Eriocheir sinensis (Es-agpat2, Es-agpat3, and Es-agpat4). The mRNA levels of Es-agpat2 and Es-agpat4 demonstrated a conspicuous presence in the hepatopancreas, with subsequent high levels in the heart, muscle, and thoracic ganglion. On the other hand, the thoracic ganglion exhibited abundant levels of Es-agpat3, while other tissues recorded relatively low expression levels. Observing the molting cycle of E. sinensis, the hepatopancreas showed minimum expression levels of Es-agpat2 and Es-agpat4 at stage A/B. A peak at stage C was noted, which was then followed by a gradual drop until stage E. For the ovarian development cycle, stage II witnessed the maximum expression level of Es-agpat2 and Es-agpat4, succeeded by a sharp fall in stage III. After this, there was an increasing trend from stage III up to stage V. Expression of Es-agpat3 in the hepatopancreas was consistently lower than Es-agpat2 and Es-agpat4 during either the molting or ovarian development. However, in terms of ovarian expression, Es-agpat3 outperformed Es-agpat2 and Es-agpat4. It exhibited a steep increase in expression, peaking at stage II and subsequently diminishing. In situ hybridization (ISH) revealed that in stages II and IV hepatopancreas, Es-agpat4-mRNA was primarily located in fibrillar cells (F cell) and resorptive cells (R cell), with no signal from Es-agpat3. During stage II of ovarian development, both Es-agpat3-mRNA and Es-agpat4-mRNA were located in the cytoplasm of previtellogenic oocyte (PRO) and endogenous vitellogenic oocyte (EN), with no expression at stage IV. Additionally, the silencing of Es-agpat2 and Es-agpat4 caused a downward trend in the expression levels of all subsequent genes in the E. sinensis TAG synthesis pathway. To sum up, these findings suggest that the three Es-agpats may have unique functions in TAG synthesis during either the molting process or ovarian maturation of E. sinensis.
Functional transcriptome reveals hepatopancreatic lipid metabolism during the molting cycle of the Chinese mitten crab Eriocheir sinensis

Li Z, Zhang G, Pan K, Niu X, Shu-Chien AC, Chen T, et al.

Comp Biochem Physiol A Mol Integr Physiol, 2023 Oct;284:111474.
PMID: 37406959 DOI: 10.1016/j.cbpa.2023.111474

Crustacean molting is highly related to energy and lipid metabolism. This study was conducted to detect the changes of total lipids (TL), triacylglyceride (TAG), phospholipid (PL) and lipid droplets in hepatopancreas, and then to investigate the gene expression patterns related to hepatopancreatic lipid metabolism during the molting cycle of Chinese mitten crab Eriocheir sinensis. Hepatopancreatic TL and TAG increased significantly from post-molt stage to pre-molt stage, then decreased significantly from pre-molt stage to ecdysis stage, which is consistent to the changes of neutral lipid-rich adipocytes in hepatopancreas. By transcriptomic analysis, 65,325 transcripts were sequenced and assembled, and 28,033 transcripts were annotated. Most genes were related to energy metabolism, and the enriched genes were involved in carbohydrate and lipid metabolism and biosynthesis, especially in de novo synthesis of fatty acids and TAG, and ketone body production. Compared to the inter-molt stages, acetyl-CoA carboxylase, fatty acid synthase and other genes related to the synthesis of fatty acids were upregulated in the pre-molt stage. TAG synthesis related genes, including Glycerol-3-phosphate acyltransferase and 1-acylglycerol-3-phosphate acyltransferases, were upregulated in the post-molt stage compared to the inter-molt stage. The expression of ketone body-related genes had no significant changes during the molting cycle. Compared to the TAG synthetic pathway, ketone body biosynthesis may contribute less/secondarily to fatty acid metabolic processes, which could be involved in the other physiological processes or metabolism. In conclusion, these results showed that TAG is the major lipid deposition during inter- and pre-molt stages, and the most genes are related to the fatty acids and TAG metabolism in the hepatopancreas during the molting cycle of E. sinensis.