Impact of a novel pre-hospital stroke notification programme on acute stroke care key performance indicators in Hong Kong: a multicentre prospective cohort study with historical controls.

INTRODUCTION: Early identification and initiation of reperfusion therapy is essential for suspected acute ischaemic stroke. A pre-hospital stroke notification (PSN) protocol using FASE (facial drooping, arm weakness, speech difficulties, and eye palsy) was implemented to improve key performance indicators (KPIs) in acute stroke care delivery. We assessed KPIs and clinical outcomes before and after PSN implementation in Hong Kong. METHODS: This prospective cohort study with historical controls was conducted in the Accident and Emergency Departments of four public hospitals in Hong Kong. Patients were screened using the PSN protocol between August 2021 and February 2022. Suspected stroke patients between August 2020 and February 2021 were included as historical controls. Door-to-needle (DTN) and door-to-computed tomography (DTC) times before and after PSN implementation were compared. Clinical outcomes including National Institutes of Health Stroke Scale score at 24 hours and modified Rankin Scale score at 3 months after intravenous recombinant tissue-type plasminogen activator (IV-rtPA) were also assessed. RESULTS: Among the 715 patients (266 PSN and 449 non-PSN) included, 50.8% of PSN patients and 37.7% of non-PSN patients had a DTC time within 25 minutes (P<0.001). For the 58 PSN and 134 non-PSN patients given IV-rtPA, median DTN times were 67 and 75.5 minutes, respectively (P=0.007). The percentage of patients with a DTN time within 60 minutes was higher in the PSN group than in the non-PSN group (37.9% vs 21.6%; P=0.019). No statistically significant differences in clinical outcomes were observed. CONCLUSION: Although the PSN protocol shortened DTC and DTN times, clinical outcomes did not significantly differ.

Antioxidant responses to benzo[a]pyrene and Aroclor 1254 exposure in the green-lipped mussel, Perna viridis.

In this study, the green-lipped mussel, Perna viridis (L.), was exposed to two concentrations of benzo[a]pyrene (B[a]P) (0.3 microg l(-1); 3 microg l(-1)) and two concentrations of Aroclor 1254 (0.5 microg l(-1); 5 microg l(-1)). In addition, a mixture of the contaminants was used (0.3 microg l(-1) B[a]P+0.5 microg l(-1) Aroclor 1254; 3 microg l(-1) B[a]P+5 microg l(-1) Aroclor 1254). All concentrations were nominal. A suite of enzymes [glutathione S transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR)], glutathione (GSH) level and lipid peroxidation (LPO) in the mussel gill and hepatopancreas were monitored over 18 days. CAT and GSH in gill tissue were positively correlated with concentration of Aroclor 1254. Activity of hepatic GST and SOD was significantly related to body burden of Aroclor 1254. LPO, GR and GPx in gill and hepatopancreas and hepatic GST were positively correlated with B[a]P concentration. The results indicate the importance of using biomarkers specific to the type of contaminant(s) that are likely to be present. Controlled laboratory experiments, such as this study, are useful in ascertaining biomarkers suitable for use with complex contaminant mixtures in the marine environment.

Relationships between tissue concentrations of chlorinated hydrocarbons (polychlorinated biphenyls and chlorinated pesticides) and antioxidative responses of marine mussels, Perna viridis.

Marine mussels, Perna viridis, were transplanted from a reference site to various polluted sites around Hong Kong. After 30 d of exposure, antioxidative responses in the gills and hepatopancreas and tissue concentrations of chlorinated hydrocarbons [polychlorinated biphenyls (PCBs) and chlorinated pesticides (CPs)] were determined for individual mussels. Glutathione S transferase (GST) and glutathione (GSH) were positively correlated with tissue PCB concentrations. Only one of the enzymatic antioxidants, glutathione peroxidase (GPx), showed significant response to tissue PCB. No significant correlation was found between tissue concentrations of chlorinated hydrocarbons and other enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and NADPH DT-diaphorase (DT-d). Oxidative stress, measured as thiobarbituric acid reactive substances, was correlated with chlorinated pesticide concentrations in tissues. This study demonstrated a correlation between GST/ GSH and chlorinated hydrocarbons. The apparent lack of correlation between trace organic pollutants and some of the enzymatic antioxidants may be due to the inhibitory effects caused by these chemicals. The above results suggest that more investigations are needed before these enzymes can be used as biomarkers.

Mathematical modeling of PCB bioaccumulation in Perna viridis.

In the present work, we built a mathematical model of polychlorinated biphenyl (PCB) bioaccumulation in Perna viridis, namely, a one-compartment model with a time dependent incorporation rate R (microg g(-1) lipid per ppb water per day), with positive substrate cooperativity as the underlying physical mechanism. The temporal change of the PCB concentration Q (microg g(-1) lipid) in the soft tissues of the mussel depends on the competition of the input rate R Wand the output rate kQ, where W is the concentration of PCB in water (ppb water) and k is the elimination rate (per day). From our experimental data, k = 0.181 +/- 0.017 d(-1). The critical concentration in water Wc for positive substrate cooperativity was found to be approximately 2.4 ppb. Below Wc, R is a constant. For a water concentration of 0.5 ppb Aroclor 1254, R = 24.0 +/- 2.4 microg g(-1) lipid ppb(-1) d(-1). Above Wc, positive substrate cooperativity comes into effect and R becomes a function of time and dependent on the concentration Q in a form R = gammaQ/(Q + delta). This is the case for a water concentration of 5 ppb Aroclor 1254, where gamma = 15.1 microg g(-1) lipid ppb(-1) d(1) and delta approximately 200 microg g(-1) lipid. From this model, the uptake is exponentially increasing when the PCB concentration in the mussel is small compared to 200 microg g(-1) lipid, and hyperbolically increasing when the concentration is large compared to 200 microg g(-1) lipid, which are consistent with the experimental data. The model is useful for understanding the true processes taking place during the bioaccumulation and for risk assessment with higher confidence. Future experimental data which challenge the present model are anticipated and in fact desirable for improvement and perfection of