Poisoning by toxic plants in Hong Kong: a 15-year review

INTRODUCTION

Hong Kong has a great diversity of plants, many of which are toxic to humans. The aim of this study was to identify the plant species most commonly involved in cases of plant poisoning in Hong Kong and to provide clinicians with a reference tool for the diagnosis and management of plant poisoning.

METHODS

We retrospectively reviewed all plant poisoning cases referred to the Hospital Authority Toxicology Reference Laboratory from 1 January 2003 to 31 December 2017. Demographics, clinical presentation, laboratory findings, treatment and outcomes of patients, as well as morphological identification and analytical testing of the plant specimens, were investigated.

RESULTS

A total of 62 cases involving 26 poisonous plant species were identified, among which Alocasia macrorrhizos (Giant Alocasia), Gelsemium elegans (Graceful Jessamine), and Rhododendron (Azalea) species were the three most commonly encountered. Gastrointestinal toxicity (n=30, 48%), neurological toxicity (n=22, 35%), and hepatotoxicity (n=6, 10%) were the three most common clinical problems. Forty-nine (79%) and eight (13%) patients had mild and moderate toxicity, respectively; they all recovered shortly with supportive treatment. The remaining five (8%) patients experienced severe toxicity requiring intensive care support. Most patients (n=61, 98%) used the plants intentionally: as a medicinal herb (n=31), as food (n=29), and for attempting suicide (n=1). Reasons for using the poisonous plants included misidentification (n=34, 55%), unawareness of the toxicity (n=20, 32%), and contamination (n=6, 10%).

CONCLUSIONS

Although most plant exposure resulted in a self-limiting disease, severe poisonings were encountered. Epidemiology of plant poisonings is geographically specific. Clinicians should be aware of local poisonous plants and their toxicities.

9-year review of new psychoactive substance use in Hong Kong: A clinical laboratory perspective

Background:

New psychoactive substances are constantly evolving structural analogues of traditional drugs of abuse that have become a threat to public health worldwide and within our locality. An understanding of the local pattern of new psychoactive substance use will help guide frontline clinical management.

Objectives:

This study was conducted to review the new psychoactive substances detected in cases referred to the authors’ laboratory (a tertiary clinical toxicology centre), as well as the associated clinical features and toxicological findings.

Methods:

All cases referred to the laboratory for toxicology analysis between January 2009 and December 2017, and which were analytically confirmed to involve new psychoactive substance use, were retrospectively reviewed. Demographic data, clinical features and toxicology findings were studied.

Results:

A total of 111 cases involving 104 patients and 22 types of new psychoactive substances were identified, with an increasing trend in the number of cases and subclass of new psychoactive substances detected. Up to half of the cases (n = 64) were related to the use of 2-phenyl-2-(ethylamino)-cyclohexanone (2-oxo-PCE, a ketamine analogue); other new psychoactive substances detected included para-methoxymethamphetamine, 4-fluoroamphetamine, phenazepam, 3-trifluoromethylphenylpiperazine, 5-methoxy-diisopropyltryptamine, 2-diphenylmethylpyrrolidine, methoxyphenidine, the N-methoxybenzyl drugs, cathinones, synthetic cannabinoids and opioids. Among the acute poisoning cases attributable to new psychoactive substance use, the severity was fatal (n = 3), severe (n = 17), moderate (n = 67) and minor (n = 17). And 11 patients required intensive care unit admission. All three fatal cases were associated with para-methoxymethamphetamine use.

Conclusion:

A rising trend of new psychoactive substance use is observed locally, which is associated with considerable morbidity and mortality. Continued vigilance from frontline clinicians and medical professionals is imperative in the combat against new psychoactive substance use.

Microfluidic platforms for rapid screening of cancer affinity reagents by using tissue samples

Cancer is the most serious disease worldwide, and ovarian cancer (OvCa) is the second most common type of gynecological cancer. There is consequently an urgent need for early-stage detection of OvCa, which requires affinity reagent biomarkers for OvCa. Systematic evolution of ligands by exponential enrichment (SELEX) and phage display technology are two powerful technologies for identifying affinity reagent biomarkers. However, the benchtop protocols for both screening technologies are relatively lengthy and require well-trained personnel. We therefore developed a novel, integrated microfluidic system capable of automating SELEX and phage display technology. Instead of using cancer cell lines, it is the first work which used tissue slides as screening targets, which possess more complicated and uncovered information for affinity reagents to recognize. This allowed for the identification of aptamer (nucleic acid) and peptide probes specific to OvCa cells and tissues. Furthermore, this developed system could be readily modified to uncover affinity reagents for diagnostics or even target therapy of other cancer cell types in the future.

Automated selection of aptamers against cholangiocarcinoma cells on an integrated microfluidic platform

An integrated microfluidic system capable of automatically identifying aptamers specific to cholangiocarcinoma (CCA) cells was developed herein. The developed system was capable of performing cell-based systematic evolution of ligands via an exponential enrichment (Cell-SELEX) process on-chip, and only six rounds of Cell-SELEX were required to identify high specificity aptamers; this represents a significant improvement in speed over conventional SELEX, in which 15-20 rounds are typically required. Using the microfluidic chip developed, three aptamers specific to CCA cells (one for SNU-478 cells and two for HuCCT-1 cells) were successfully screened. This automated system could be modified to uncover aptamer probes against other cancer cells, thereby allowing for earlier diagnosis and consequently a potentially improved prognosis.

A Microfluidic Chip for Detecting Cholangiocarcinoma Cells in Human Bile

Cholangiocarcinoma (CCA), a biliary tract malignancy, accounts for 20% of all liver cancers. There are several existing methods for diagnosis of CCA, though they are generally expensive, laborious, and suffer from low detection rates. Herein we first developed a means of partially purifying human bile for consequent injection into a microfluidic chip. Then, the novel microfluidic system, which featured 1) a cell capture module, 2) an immunofluorescence (IF) staining module featuring two CCA-specific biomarkers, and 3) an optical detection module for visualization of antibody probes bound to these CCA marker proteins, was used to detect bile duct cancer cells within partially purified bile samples. As a proof of concept, CCA cells were successfully captured and identified from CCA cell cultures, blood samples inoculated with CCA cells, and clinical bile specimens. In 7.5 ml of bile, this system could detect >2, 0, and 1 positive cells in advanced stage patients, healthy patients, and chemotherapy-treated patients, respectively. In conclusion, our microfluidic system could be a promising tool for detection of cancer cells in bile, even at the earliest stages of CCA when cancer cells are at low densities relative to the total population of epithelial cells.

An integrated microfluidic system for the isolation and detection of ovarian circulating tumor cells using cell selection and enrichment methods

Gynecological cancer is difficult to be diagnosed at early stages. The relatively high mortality rate has been a serious issue accordingly. We herein reported a diagnosis method by using circulating tumor cells (CTCs) which have been extensively explored as a potential tool for diagnostics and prognostics of ovarian cancers. Nonetheless, the detection of CTCs still remains a challenge because of the difficulty in isolating them from whole blood samples since they are shed into the vasculature from primary tumors and circulate irregularly in the bloodstream in extremely low concentrations. In this work, we reported a new, integrated microfluidic system capable of (1) red blood cells lysis, (2) white blood cell (WBC) depletion via a negative selection process, and (3) capture of target cancer cells from whole blood samples using aptamer-binding technology. Furthermore, this is the first time that an aptamer was used to capture ovarian cancer cells owing to its high affinity. The new microfluidic chip could efficiently perform the entire process in one hour without human intervention at a high recovery rate and a low false positive detection rate when compared with antibody-based systems. A high recovery rate for the isolation of CTCs within a short period of time has been reported when compared to the traditional negative or positive selection approach by using traditional antibody biomarkers. More importantly, "false positive" results from WBCs could be significantly alleviated due to the high specificity of the cancer cell-specific aptamers. The developed integrated microfluidic system could be promising for the isolation and detection of CTCs, which could be used for early diagnosis and prognosis of cancers.

Microfluidics in the selection of affinity reagents for the detection of cancer: paving a way towards future diagnostics

Microfluidic technologies have miniaturized a variety of biomedical applications, and these chip-based systems have several significant advantages over their large-scale counterparts. Recently, this technology has been used for automating labor-intensive and time-consuming screening processes, whereby affinity reagents, including aptamers, peptides, antibodies, polysaccharides, glycoproteins, and a variety of small molecules, are used to probe for molecular biomarkers. When compared to conventional methods, the microfluidic approaches are faster, more compact, require considerably smaller quantities of samples and reagents, and can be automated. Furthermore, they allow for more precise control of reaction conditions (e.g., pH, temperature, and shearing forces) such that more efficient screening can be performed. A variety of affinity reagents for targeting cancer cells or cancer biomarkers are now available and will likely replace conventional antibodies. In this review article, the selection of affinity reagents for cancer cells or cancer biomarkers on microfluidic platforms is reviewed with the aim of highlighting the utility of such approaches in cancer diagnostics.

Continuous nucleus extraction by optically-induced cell lysis on a batch-type microfluidic platform

The extraction of a cell's nucleus is an essential technique required for a number of procedures, such as disease diagnosis, genetic replication, and animal cloning. However, existing nucleus extraction techniques are relatively inefficient and labor-intensive. Therefore, this study presents an innovative, microfluidics-based approach featuring optically-induced cell lysis (OICL) for nucleus extraction and collection in an automatic format. In comparison to previous micro-devices designed for nucleus extraction, the new OICL device designed herein is superior in terms of flexibility, selectivity, and efficiency. To facilitate this OICL module for continuous nucleus extraction, we further integrated an optically-induced dielectrophoresis (ODEP) module with the OICL device within the microfluidic chip. This on-chip integration circumvents the need for highly trained personnel and expensive, cumbersome equipment. Specifically, this microfluidic system automates four steps by 1) automatically focusing and transporting cells, 2) releasing the nuclei on the OICL module, 3) isolating the nuclei on the ODEP module, and 4) collecting the nuclei in the outlet chamber. The efficiency of cell membrane lysis and the ODEP nucleus separation was measured to be 78.04 ± 5.70% and 80.90 ± 5.98%, respectively, leading to an overall nucleus extraction efficiency of 58.21 ± 2.21%. These results demonstrate that this microfluidics-based system can successfully perform nucleus extraction, and the integrated platform is therefore promising in cell fusion technology with the goal of achieving genetic replication, or even animal cloning, in the near future.

An integrated microfluidic system for screening of phage-displayed peptides specific to colon cancer cells and colon cancer stem cells

Affinity reagents recognizing biomarkers specifically are essential components of clinical diagnostics and target therapeutics. However, conventional methods for screening of these reagents often have drawbacks such as large reagent consumption, the labor-intensive or time-consuming procedures, and the involvement of bulky or expensive equipment. Alternatively, microfluidic platforms could potentially automate the screening process within a shorter period of time and reduce reagent and sample consumption dramatically. It has been demonstrated recently that a subpopulation of tumor cells known as cancer stem cells possess high drug resistance and proliferation potential and are regarded as the main cause of metastasis. Therefore, a peptide that recognizes cancer stem cells and differentiates them from other cancer cells will be extremely useful in early diagnosis and target therapy. This study utilized M13 phage display technology to identify peptides that bind, respectively, to colon cancer cells and colon cancer stem cells using an integrated microfluidic system. In addition to positive selection, a negative selection process was integrated on the chip to achieve the selection of peptides of high affinity and specificity. We successfully screened three peptides specific to colon cancer cells and colon cancer stem cells, namely, HOLC-1, HOLC-2, and COLC-1, respectively, and their specificity was measured by the capture rate between target, control, and other cell lines. The capture rates are 43.40 ± 7.23%, 45.16 ± 7.12%, and 49.79 ± 5.34% for colon cancer cells and colon cancer stem cells, respectively, showing a higher specificity on target cells than on control and other cell lines. The developed technique may be promising for early diagnosis of cancer cells and target therapeutics.

Screening of aptamers specific to colorectal cancer cells and stem cells by utilizing On-chip Cell-SELEX

Colorectal cancer (CRC) is the most frequently diagnosed cancer around the world, causing about 700,000 deaths every year. It is clear now that a small fraction of CRC, named colorectal cancer stem cells (CSCs) exhibiting self-renewal and extensive proliferative activities, are hard to be eradicated. Unfortunately, highly specific biomarkers for colorectal CSC (CR-CSCs) are lacking that prohibits the development of effective therapeutic strategies. This study designed and manufactured a novel microfluidic system capable of performing a fully automated cell-based, systematic evolution of ligands by exponential enrichment (SELEX) process. Eight CR-CSC/CRC-specific aptamers were successfully selected using the microfluidic chip. Three of the aptamers showed high affinities towards their respective target cells with a dissociation constant of 27.4, 28.5 and 12.3 nM, which are comparable to that of antibodies.

An on-chip Cell-SELEX process for automatic selection of high-affinity aptamers specific to different histologically classified ovarian cancer cells

Ovarian cancer (OvCa) is the second most common type of gynecological cancer. More seriously, the prognosis for survival is relatively poor if an early OvCa diagnosis is not achieved. However, it is extremely challenging to diagnose very early stage OvCa, when treatments are the most effective, because of the lack of specific and sensitive biomarkers. Therefore, in order to achieve early detection of OvCa, screening and identifying biomarkers with high specificity and affinity are greatly needed. In this study, an integrated microfluidic system capable of performing cell-based systematic evolution of ligands by an exponential enrichment (Cell-SELEX) process was developed for automatic, high-throughput screening of multiple cell lines to competitively select aptamer-based biomarkers for OvCa. This on-chip Cell-SELEX process only required five rounds of aptamer selection, which is much faster than using a conventional SELEX process (22 rounds). Using this on-chip process, 13 aptamers specific to OvCa cells were successfully screened and three of them showed high affinity towards target cells with dissociation constants of 1.8 nM, 8.3 nM, and 1.3 nM. Analysis of stained fluorescence images and competitive testing against multiple cancer cell lines (cervical cancer, breast cancer, lung cancer, and liver cancer) were performed to verify the specificity of these selected aptamers. The results demonstrated that this developed system could perform the on-chip Cell-SELEX selection successfully and could be applied for personalized aptamer screening or targeted therapy monitoring in the near future.

Rapid detection of influenza A virus infection utilizing an immunomagnetic bead-based microfluidic system

This study reports a new immunomagnetic bead-based microfluidic system for the rapid detection of influenza A virus infection by performing a simple two-step diagnostic process that includes a magnetic bead-based fluorescent immunoassay (FIA) and an end-point optical analysis. With the incorporation of monoclonal antibody (mAb)-conjugated immunomagnetic beads, target influenza A viral particles such as A/H1N1 and A/H3N2 can be specifically recognized and are bound onto the surface of the immunomagnetic beads from the specimen sample. This is followed by labeling the fluorescent signal onto the virus-bound magnetic complexes by specific developing mAb with R-phycoerythrin (PE). Finally, the optical intensity of the magnetic complexes can be analyzed immediately by the optical detection module. Significantly, the limit of detection (LOD) of this immunomagnetic bead-based microfluidic system for the detection of influenza A virus in a specimen sample is approximately 5×10(-4) hemagglutin units (HAU), which is 1024 times better than compared to conventional bench-top systems using flow cytometry. More importantly, the entire diagnostic protocol, from the purification of target viral particles to optical detection of the magnetic complexes, can be automatically completed within 15 min in this immunomagnetic bead-based microfluidic system, which is only 8.5% of the time required when compared to a manual protocol. As a whole, this microfluidic system may provide a powerful platform for the rapid diagnosis of influenza A virus infection and may be extended for diagnosis of other types of infectious diseases with a high specificity and sensitivity.

Mechanisms of calcium oxalate crystal attachment to injured renal collecting duct cells

BACKGROUND

Renal cell or tissue injury results in a loss of membrane lipid asymmetry and/or loss of cell polarity, and both events lead to changes on the surface of the cell membranes that enhance crystal attachment. We have proposed two distinct mechanisms of crystal attachment following membrane changes induced by various modes of injury.

METHODS

Annexin V was used to determine whether phosphatidylserine (PS) exposure on the cell membrane surface plays a role in calcium oxalate monohydrate (COM) crystal attachment to cells that have lost their polarity as well as to cells that have lost their lipid asymmetry. We utilized two different experimental models of injury to renal epithelial cells in culture. The first model used calcium ionophore A23187 to induce a loss of lipid asymmetry, and the second model used EGTA to break down tight junctions and lose cell polarity.

RESULTS

Inner medullary collecting duct cells that have lost lipid asymmetry demonstrated an increase in the number of cells that bound annexin V. However, when cells lost their polarity, they did not bind annexin V. In addition, the attachment of crystals to cells following a loss of cell polarity was not inhibited by annexin V.

CONCLUSIONS

This study indicates that both individual cell injury (loss of lipid asymmetry) and generalized cell monolayer injury (loss of cell polarity) result in the presentation of different cell surfaces and that both forms of injury result in an increased affinity for crystal attachment. Both mechanisms could be important independently or collectively in the retention of microcrystals to renal collecting duct cells in urolithiasis.

Protein 4.1 R-135 interacts with a novel centrosomal protein (CPAP) which is associated with the gamma-tubulin complex

Using a yeast two-hybrid system, we isolated a novel human centrosomal protein, CPAP (centrosomal P4.1-associated protein), which specifically interacts with the head domain of the 135-kDa protein 4.1R isoform (4.1R-135). Sequence analysis revealed that the carboxyl terminus of CPAP has 31.3% amino acid identity with human Tcp-10 (a t-complex responder gene product). Interestingly, most of the sequence identity is restricted to two conserved regions. One carries a leucine zipper, which may form a series of heptad repeats involved in coiled-coil formation; the other contains unusual glycine repeats with unknown function. Immunofluorescence analysis revealed that CPAP and gamma-tubulin are localized within the centrosome throughout the cell cycle. CPAP cosediments with gamma-tubulin in sucrose gradients and coimmunoprecipitates with gamma-tubulin, indicating that CPAP is a part of the gamma-tubulin complex. Furthermore, functional analysis revealed that CPAP is localized within the center of microtubule asters and may participate in microtubule nucleation. The formation of microtubule asters was significantly inhibited by anti-CPAP antibody. Together, these observations indicate that CPAP may play an important role in cell division and centrosome function.

Oxalate-induced exposure of phosphatidylserine on the surface of renal epithelial cells in culture

A molecular mechanism of crystal attachment to renal cells after injury has been proposed in which the exposure of phosphatidylserine (PS) on the cell membrane surface following injury provides attachment sites for calcium-containing crystals. Annexin V was used to determine whether injury to kidney cells by oxalate in culture resulted in PS exposure on the cell surface. When continuous cultures of intermedullary collecting duct cells were exposed to various levels of oxalate, a dose-dependent increase in PS exposure was observed on the cell surfaces. Initially, only scattered cells expressed PS on the surface. However, as the level of oxalate increased, groups of cells began to express PS, suggesting that the injured cells may have an influence on neighboring cells. Exposure of PS on the cell membrane surface correlated with a corresponding increase in calcium oxalate monohydrate crystal attachment to the cells. This indicates that damage to kidney epithelial cells by elevated concentrations of urinary components, in this case oxalate, could result in exposure of PS on cells, which could provide a point of fixation or nucleation for calcium-containing crystals.

Clinical distinction between acute hemorrhagic and acute ischemic stroke by Siriraj stroke score

BACKGROUND

The clinical distinction between hemorrhagic and ischemic stroke cannot be achieved by simple clinical evaluation, and it is impossible to submit all stroke patients to computed tomography. A simple, reliable, and safe diagnostic tool for acute stroke syndrome is needed. This study tested the Siriraj stroke score to verify its accuracy for distinguishing among the pathological subtypes of stroke.

METHODS

This study included the one hundred and seventy-one patients with acute supratentorial stroke syndromes consecutively admitted to the Emergency Room of the Taichung Veterans General Hospital from April 1 to September 30, 1993. The Siriraj stroke score was calculated, then compared with results of computed tomography. The Siriraj stroke score was calculated as (2.5 x level of consciousness) + (2 x vomiting) + (2 x headache) + (0.1 x diastolic blood pressure) - (3 x atheroma markers) - 12. A score above 1 indicates supratentorial intracranial hemorrhage, while a score below -1 indicates infarction. The score between 1 and -1 represents an equivocal result needing further evaluation to verify diagnosis.

RESULTS

The diagnostic sensitivities of the Siriraj stroke score for intracranial hemorrhage and infarction were 85% and 90% respectively, with an overall predictive accuracy of 88.5%. When three cases with subarachnoid hemorrhage whose scores were all above 1 were excluded, the sensitivities for cerebral hemorrhage and infarction were 83.8% and 90% respectively, with an overall predictive accuracy of 88.2%.

CONCLUSIONS

The Siriraj stroke score can be used as a reliable bedside method for diagnosing acute stroke and for deciding which patients should have priority for computed tomography, it is also a valuable tool for epidemiology studies of stroke incidence and outcome.