Detection of tetrodotoxin by HPLC in shellfishes and goby from south Taiwan

High performance liquid chromatography (HPLC) using fluorescent detection following post-column alkaline degradation and a sample preparation procedure for the analysis were established to detect tetrodotoxins (TTXs) in seafood. In south Taiwan Prefectures, each specimen of shellfishes and gobies, collected from Chiayi, Tainan, and Pingtung from January 1997 to May 1998, was analyzed by HPLC to detect the presence and quantity of TTXs. Overall results showed that only 5 specimens out of 557 specimens contained TTXs; the toxic species were gastropod Natica lineata and Nassarius livescens. The highest TTX content is 10.0 microg/g in N. livescens. Gobies and other species of shellfishes were nontoxic. Although the rate of toxic specimens in all samples was low and showed no seasonal trends, the TTX contents of toxic specimens were higher than safety criteria value.

Histoenzymological and ultrastructural changes in lateral muscle fibers of Oreochromis niloticus (Teleostei: Cichlidae) after local injection of veratrine

The effects of veratrine have been investigated in mammalian, amphibian, and crustacean muscle, but not in fish. In this work, the action of veratrine was studied in the lateral muscle of the freshwater teleost Oreochromis niloticus after intramuscular injection. Histoenzymological typing and electron microscopy of muscle fibers before and 15, 30, and 60 min after veratrine injection (10 ng/kg fish) were used to indirectly assess the morphological changes and the oxidative and m-ATPase activities. In some cases, muscles were pretreated with tetrodotoxin to determine whether the ultrastructural changes were the result of Na(+) channel activation by veratrine. Veratrine altered the metabolism of fibers mainly after 30 min. Oxidative fibers showed decreased NADH-TR activity, whereas that of glycolytic and oxidative-glycolytic type fibers increased. There was no change in the m-ATPase activity of the three fiber types, except at 60 min postveratrine, when a novel fiber type, which showed no reversal after acidic and alkaline preincubations, appeared. Ultrastructural damage involved sarcomeres, myofibrils, and mitochondria, but the T-tubules remained intact. Pretreatment with tetrodotoxin (1 ng/ml) prevented the ultrastructural changes caused by veratrine. These results show that in fish skeletal muscle veratrine produces some effects that are not seen in mammalian muscle.

Modulation of tetrodotoxin-resistant sodium channels by dihydropyrazole insecticide RH-3421 in rat dorsal root ganglion neurons

The effects of the dihydropyrazole insecticide RH-3421 on the retrodotoxin-resistant (TTX-R) voltage-gated sodium channels in rat dorsal root ganglion (DRG) neurons were studied using the whole-cell patch clamp technique. RH-3421 at 10 nM to 1 microM completely blocked action potentials. The sodium currents were irreversibly suppressed by 1 microM RH-3421 in a time- and a dose-dependent manner and the IC50 value of RH-3421 was estimated to be 0.7 microM after 10 min of application. RH-3421 blocked the sodium currents to the same extent over the entire range of test potentials. The sodium conductance-voltage curve was not shifted along the voltage axis by 1 microM RH-3421 application In contrast, both fast and slow steady-state sodium channel inactivation curves were shifted in the hyperpolarizing direction in the presence of 1 microM RH-3421. It was concluded that RH-3421 bound to the resting and inactivated sodium channels to cause block with a higher affinity for the latter state.

Effect of tetrodotoxin (TTX) on some brain neurotransmitters in rats

Tetrodotoxin (TTX) is a potent marine neurotoxin named after the order of fish from which it is most commonly associated, the Tetraodontiforms, or the tetraodon pufferfish. In the present study the crude TTX was extracted from pufferfish Lagocephalus sceleratus collected from the Red Sea in Egypt. The LD100 and LD50 of crude TTX were found to be 8.33 and 6.26 mg/kg for the gonad extract and 41.8 and 27.9 mg/kg for the skin extract, respectively. This indicates that the gonad TTX is more lethal than the skin. The effects of both gonad and skin TTX extracts on the levels of brain serotonine, acetylcholine, histamine, norepinephrine, and epinephrine were studied in rats. Brain serotonine level was significantly increased and reached its peak level after 4 hours (P<0.001) of TTX administration. Brain acetylcholine, histamine, and norepinephrine levels were also significantly increased but reached peak level after 6 hours (P<0.001). The effect of the gonad extract was more significantly profound and of longer duration than the skin extract. On the other hand, brain epinephrine did not show any significant change during the experimental period.

Occurrence of tetrodotoxin in the skin of a rhacophoridid frog Polypedates sp. from Bangladesh

Twenty-three specimens of a tree-frog Polypedates sp. were collected from two locations (Mymensingh and Barisal) of Bangladesh in 1999, and assayed for their toxicity scores and toxin principle. Among the tissues, only the skin of the Mymensingh specimens was found to be toxic in mouse test, with the toxicity scores of 31-923MU/g. The toxin isolated from the skin was analyzed by high-performance liquid chromatography, electrospray ionization-time of flight mass spectrometry and proton nuclear magnetic resonance, and characterized as tetrodotoxin, a toxin principle.

Delayed haemolytic activity by the freshwater puffer Tetraodon sp. toxin

In order to elucidate the toxin composition of the freshwater puffer in Bangladesh, about 230 specimens of Tetraodon sp. were collected from 1997 to 1999 and extracted. After partitioning the toxins between an aqueous layer and a 1-butanol layer, the toxin in the aqueous layer was characterized as paralytic shellfish poison (PSP) (data not shown), while the toxin in the 1-butanol layer was identified as palytoxin (PTX) or PTX-like substance based on the delayed haemolytic activity which was inhibited by an anti-PTX antibody and ouabain (g-strophanthin). This is the first report on the occurrence of PTX or PTX-like substance(s) in puffer fish.

Occurrence of tetrodotoxin-related substances in the nontoxic puffer Takifugu xanthopterus

Instead of tetrodotoxin, significant amounts of tetrodotoxin-related substances with no mouse lethality were detected in the nontoxic liver specimen of puffer fish, Takifugu xanthopterus. The tetrodotoxin-related substances, which were demonstrated to be tetrodotoxin derivatives by gas chromatography-mass spectrometry analysis, were similar to tetrodonic acid in HPLC but distinguishable from it in electrophoresis. Our results suggest that nontoxic puffer fish contains nontoxic tetrodotoxin derivatives as precursors or metabolites of tetrodotoxin.

Chelonodon patoca, a highly toxic marine puffer in Japan

Toxicity of a Japanese marine puffer Chelonodon patoca ("okinawafugu") was examined by mouse assay from 1996 to 1999. Frequency of the toxic specimens was found to be 100% with high toxicity scores. Among the tissues tested, toxicity in the skin ranged from 60 to 6,700 MU/g, in the ovary from 25 to 670 MU/g, in the testis from 45 to 550 MU/g, in the muscle from 2 to 390 MU/g, and in the liver from 5 to 380 MU/g. The liver, which is known as one of the most toxic organs in Japanese marine puffer in general, showed lower toxicity in the present study. Thus, the anatomical distribution of toxicity was unique in C. patoca, in comparison with that of other Japanese puffers. C. patoca toxin was characterized as tetrodotoxin (TTX), 4-epiTTX and anhydroTTX by HPLC.

Differences in action potential and early afterdepolarization properties in LQT2 and LQT3 models of long QT syndrome

1. Long OT syndrome has many causes from both acquired and congenital disorders. For the congenital disorders, their presentation and disease course are not identical. We studied two pharmacological models of long QT syndrome (LQT) to identify differences in cellular electrophysiological properties that may account for this. LQT2 was simulated by suppression of the rapidly activating delayed rectifier potassium current (I(Kr)) with the drug E-4031, and LQT3 was simulated by slowing of the sodium current (I(Na)) decay with the toxin ATX II. 2. Single rabbit ventricular cell action potentials were studied using the amphotericin B perforated patch clamp technique. Action potential and early afterdepolarization (EAD) properties were rigorously defined by the frequency power spectra obtained with fast Fourier transforms. 3. The E-4031 (n=43 myocytes) and ATX II (n=50 myocytes) models produced different effects on action potential and EAD properties. The major differences are that ATX II, compared with E-4031, caused greater action potential prolongation, more positive plateau voltages, lower amplitude EADs with less negative take-off potentials, greater time to the EAD peak voltage, and longer duration EADs. Despite causing greater action potential prolongation, the incidence of EAD induction was much less with the ATX II model (28%) than with the E-4031 model (84%). Thus these two pharmacological models have strikingly different cellular electrophysiological properties. 4. Our findings provide cellular mechanisms that may account for some differences in the clinical presentation of LQT2 and LQT3.

A rapid hemolysis assay for the detection of sodium channel-specific marine toxins

Current methods of detection for fish and shellfish biotoxins in monitoring and research purposes are either labor intensive, expensive, require specialized techniques or all of the above. This paper reports on the development of a fairly sensitive, rapid, and inexpensive assay which detects the presence of compounds that affect the sodium channel. It is based on the principles of the mouse neuroblastoma tissue culture assay for sodium channel specific-biotoxins using red blood cells (RBCs) from the red tilapia (Sarotherodon mossambicus). This assay has the potential to complement the use of live animal bioassay testing for marine toxins. Veratridine, a sodium channel activator and ouabain, an inhibitor of Na(+)/K(+) ATPase, both react with the tilapia RBCs by affecting the permeability of the cell's membrane. Saxitoxin (STX), its analogs, and tetrodotoxin (TTX) can inhibit the action of veratridine and ouabain leaving the cell morphologically normal. By sequencing the addition of veratridine and ouabain, with either the extracted samples, saxitoxin, tetrodotoxin, or ciguatoxin (CTX-a sodium channel activator) to the RBCs a sodium channel antagonist or activator can be detected. Results using pure concentrations of a sodium channel-specific toxin could be detected to inhibit hemolysis at a concentration of 0.3 microg/ml STX, 3.5 microg/ml for neo-STX, 3.0 microg/ml for GTX, and 5.0 microgl for TTX in the presence of ouabain and veratridine. CTX was detected at a concentration of 50 microg/ml. The RBCs from the red tilapia was used due to the fish's ability to osmoregulate its internal environment to survive in both fresh and saltwater. In addition, with growing opposition to live animal testing, this assay has been designed as a non-lethal means of testing for sodium channel affecting marine toxins. No test animals are sacrificed and blood may be drawn from the same fish for continued sample testing.

Frequent occurrence of paralytic shellfish poisoning toxins as dominant toxins in marine puffer from tropical water

Considerably high toxicity was detected in marine puffers collected from Masinloc Bay, Philippines. The toxicity was detected in the liver, intestine, muscle and skin. Noteworthy, the specimens, the muscle of which showed high toxicity, appeared in high frequency, indicating that puffers from this area is not safe for human consumption. These puffer specimens contained paralytic shellfish poisoning (PSP) toxins, often as major toxin components, the profile of which was similar to that of freshwater puffers reported from tropical areas. These results indicate that PSP toxins are common in tropical puffers both from marine and freshwater.

The uniform field and pattern ERG in macaques with experimental glaucoma: removal of spiking activity

PURPOSE

To determine whether the uniform field and pattern ERGs that are reduced in macaque eyes with experimental glaucoma have the same inner-retinal origins.

METHODS

ERGs were recorded from 14 anesthetized adult macaques using DTL electrodes. Six monkeys had laser-induced experimental glaucoma, and two others received intravitreal injections of tetrodotoxin (TTX, 6 microM) to block spiking activity of inner-retinal neurons. The remaining 6 animals were normal. Uniform fields and grating patterns (0.1-3 cpd) were square-wave modulated at 1.7 Hz (transient) and 8 Hz (steady state). The test field (42 degrees x 32 degrees) had a mean luminance of 44 cd/m2 and a contrast of 10% to 82%.

RESULTS

In normal eyes transient ERGs to uniform fields contained photopic negative responses (PhNR) after the b-wave and after the d-wave. Transient pattern electroretinograms (PERGs) at each contrast reversal showed positive (P50) potentials followed by negative (N95) potentials of time course similar to that of the PhNR. The PhNR and N95 were greatly reduced or eliminated by experimental glaucoma and by TTX. Summing responses to luminance increments and decrements of the uniform field could simulate the PERG to low spatial frequency stimuli. Further, the PERG responses to high spatial frequencies were similar to the simulation in shape but slightly delayed in time. Experimental glaucoma and TTX had similar effects on the N95 of the simulated PERG as to those on the actual PERG. However, P50 was more reduced by experimental glaucoma than by TTX, indicating a nonspiking contribution to P50. For the steady state condition, the uniform field ERG, the simulated PERG, and the actual PERG all were affected by experimental glaucoma and TTX, indicating that they contained contributions from the spiking activity of ganglion cells.

CONCLUSIONS

The changes in the uniform field and PERG responses produced by experimental glaucoma are related and are largely a consequence of reduced spiking activity of ganglion cells and their axons. These findings raise the possibility that the uniform field ERG could serve as a useful alternative to the PERG in the assessment of clinical glaucomatous neuropathy.

Neuroreceptors and ion channels as the basis for drug action: past, present, and future

This article summarizes the development of cellular neuropharmacology and neurotoxicology, based primarily on my own research. The progress of this field depends at least in part on the theoretical and technological developments of excitable cell physiology, biophysics, and biochemistry. First, a brief historical development is described. Second, my earlier studies of the mechanism of action of insecticides on the nervous system are introduced. The most significant is the early discovery of the increase in depolarizing after-potential caused by DDT and pyrethroids. This laid the foundation of subsequent analyses of sodium channel modulation as the major mechanism of action of DDT/pyrethroids. Third, my initial contributions to cellular neuropharmacology are described. The discovery of the potent and selective block of sodium channels by tetrodotoxin aroused interest not only in using this toxin and other chemicals as useful laboratory tools but also in studying receptors/channels as important targets of various drugs. Using internally perfused squid giant axons, pioneering studies of local anesthetic action led to the conclusion that these anesthetics block the sodium channel from inside the nerve membrane in the cationic form. Fourth, a few examples of my more recent studies using voltage-clamp and patch-clamp techniques are described. Pyrethroid modulation of sodium channels was analyzed in great detail, including single-channel kinetics, toxicity amplification from channels to animal behaviors, temperature dependence, selective toxicity, and vitamin E antagonism. The neuroprotective drug riluzole blocked sodium channels and high-voltage-activated calcium channels, thereby preventing excess stimulation of N-methyl-D-aspartate receptors and massive influx of calcium, thereby retarding spread of infarction in the brain. Neuronal nicotinic acetylcholine receptors have received much attention recently, and I launched an extensive study of the mechanism whereby alcohols and general anesthetics modulate their activity. Ethanol potently stimulates the alpha-bungarotoxin-insensitive, alpha4beta2-type acetylcholine receptors, thereby causing release of various transmitters; this leads to a cascade of multisynaptic events and behavioral changes. Inhalational general anesthetics augment the activity of gamma-aminobutyric acid(A) receptors and inhibit the activity of alpha4beta2-type acetylcholine receptors, causing a variety of clinical syndromes. Fifth, one of the possible future directions of cellular neuropharmacology and neurotoxicology is discussed. Emphasis is placed on the three-dimensional structure-activity relationship, in particular how changes in the molecular structure of drugs and receptors/channels result in kinetic changes in the function of receptors/channels.

Paralytic toxins in a ribbon worm Cephalothrix species (Nemertean) adherent to cultured oysters in Hiroshima Bay, Hiroshima Prefecture, Japan

In 1998, during the surveillance of the toxicity of various marine fouling organisms in Hiroshima Bay, Hiroshima Prefecture, Japan, specimens of the ribbon worm, "himomushi" Cephalothrix sp. (Nemertean) adherent to the shells of cultured oysters hanging onto floating culture rafts were found to contain toxins which showed strong paralytic action in mice throughout the survey period, February to May. The maximum toxicity (as tetrodotoxin, TTX) was 14,734 MU/g whole body. Attempts were made to identify the paralytic toxins in this worm. The "himomushi" toxin (HMT) was extracted from the worm with 80% methanol acidified with acetic acid and the extract defatted with dichloromethane. The aqueous layer was chromatographed on activated charcoal and the unbound and bound toxic fractions were analyzed by high-performance liquid chromatography and gas chromatography-mass spectrometry. It was rather unexpectedly revealed from these results that HMT was comprised of TTX, 4-epiTTX, anhydroTTX and three unidentified toxins. To our knowledge, this is the first report of the occurrence of toxic organisms, containing a high concentration of TTX, adherent to cultured bivalves such as oysters.

Involvement of the medial septum in stress-induced relapse to heroin seeking in rats

Intermittent footshock stress has been shown to reinstate extinguished drug-taking behaviour in rats, but the brain areas involved in this effect are to a large degree unknown. Here we studied the role of the septum in stress-induced reinstatement of heroin seeking. Rats were trained to self-administer heroin for 9-10 days (three 3-h sessions per day, 0.1 mg/kg per infusion). Following training, extinction sessions were given for 8-13 days by substituting saline for heroin, and then tests for reinstatement of heroin seeking were carried out. Reversible inactivation of the medial septum with tetrodotoxin (TTX; 1-5 ng, infused 25-40 min before the test sessions) reliably reinstated heroin seeking, mimicking the effect of 15 min of intermittent footshock. This effect of TTX was not observed after infusions made 1.5 mm dorsally into the lateral septum. In other experiments, it was found that infusions of a low, subthreshold dose of TTX (0.5 ng) into the medial septum, when combined with 2 min of footshock that in itself was ineffective, reinstated heroin seeking. Furthermore, electrical stimulation (400 microA pulses, 100 micros duration, 100 Hz frequency) of the medial septum during exposure to 10 min of intermittent footshock attenuated footshock-induced reinstatement of heroin seeking. These data suggest a role for the medial septum in stress-induced relapse to drug seeking. The septum is thought to be involved in neuronal processes underlying behavioural inhibition, thus we speculate that stressors provoke relapse by interfering with these processes.

Toxicities and distribution of tetrodotoxin in the tissues of puffer fish found in the coast of the Baja California Peninsula, Mexico

Toxicities and tetrodotoxin distribution in tissues of five puffer fish species commonly found in the littoral of Baja California Peninsula, Mexico (Sphoeroides annulatus, S. lobatus, S. lispus, Arothron meleagris and Canthigaster punctatissima) were evaluated by bioassay and HPLC. The toxicities estimated as tetrodotoxin-equivalents of all species were more than 0.42 microg/g in at least one of the tissues tested, and the highest was found in S. lispus liver (130 microg/g).

A tetrodotoxin-producing Vibrio strain, LM-1, from the puffer fish Fugu vermicularis radiatus

Identification of tetrodotoxin (TTX) and its derivatives produced from a Vibrio strain in the intestine of the puffer fish Fugu vermicularis radiatus was performed by thin-layer chromatography, electrophoresis, high-performance liquid chromatography, and gas chromatography-mass spectrometry, together with a mouse bioassay for toxicity. It was demonstrated that the isolated bacterium produced TTX, 4-epi-TTX, and anhTTX during cultivation, suggesting that Vibrio strains are responsible for the toxification of the puffer fish.

Comparison of sensitivity of sodium currents to tetrodotoxin in equine muscle specimens with that in murine and human muscle specimens

OBJECTIVE

To determine sensitivity of equine skeletal muscle to tetrodotoxin and compare that with sensitivity of murine and human skeletal muscles.

SAMPLE POPULATION

Semimembranosus, vastus lateralis, triceps brachii, and masseter muscle specimens from 22 euthanatized horses, vastus lateralis muscle biopsy specimens from 25 clinically normal humans, and diaphragmatic muscle specimens from 6 mice.

PROCEDURE

Electrically elicited twitch responses were measured in muscle specimens incubated in medium alone and with tetrodotoxin (100 nM, 400 nM, 1.6 microM for equine specimens and 100 nM, 200 nM, 400 nM, 800 nM, 1.6 microM for murine and human specimens). Percentages of tetrodotoxin-sensitive and -resistant sodium channels were determined and compared among muscles and species.

RESULTS

2 sodium channels with different sensitivities to tetrodotoxin were identified in equine muscle. One was blocked with 100 nM tetrodotoxin and the other was unaffected by tetrodotoxin at concentrations up to 1.6 microM. The only difference detected among the 4 equine muscles was that masseter muscle specimens had a higher percentage of tetrodotoxin-sensitive channels than triceps brachii muscle specimens. Tetrodotoxin-resistant sodium channels constituted 31 to 66% of the equine muscle twitch response, which was greater than that determined for normal human and murine muscle (< 5%).

CONCLUSION AND CLINICAL RELEVANCE

Equine skeletal muscle contains a high percentage of tetrodotoxin-resistant sodium channels. The 4 equine muscles evaluated were more similar to each other than to murine and human muscles. Shifts in expression of sodium channel subtypes may play a role in the manifestation of certain myopathies.

Subcellular distribution of tetrodotoxin in puffer fish liver

The liver homogenate of puffer fish was fractionated into blood cell, nuclear, mitochondrial, microsomal and cytosol fractions by the differential centrifugation method. All the five fractions were toxic to mice, although the toxin amount was significantly high in the cytosol fraction. Analyses by HPLC and LC-FABMS demonstrated that tetrodotoxin is the major toxic principle in each fraction. These results reveal that tetrodotoxin is widely distributed in organelles in liver cells, though predominantly in the cytosol fraction.

The organophosphate sarin, at low concentrations, inhibits the evoked release of GABA in rat hippocampal slices

In the present study, the whole-cell mode of the patch-clamp technique was applied to neurons of the CA1 pyramidal layer of rat hippocampal slices to investigate the effects of the organophosphate (OP) sarin on field stimulation-evoked and on tetrodotoxin (TTX)-insensitive postsynaptic currents (PSCs) mediated by activation of type A gamma-aminobutyric acid (GABA) receptors or AMPA-type glutamate receptors. At 0.3-1 nM, sarin reduced the amplitude of GABA-mediated PSCs and had no effect on the amplitude of glutamatergic PSCs evoked by field stimulation of neurons synaptically connected to the neuron under study. The effect of sarin on evoked GABAergic PSCs was unrelated to cholinesterase inhibition, was partially reversed upon washing of the neurons with sarin-free external solution, and was mediated by a direct interaction of the OP with muscarinic acetylcholine receptors present on presynaptic GABAergic neurons. Sarin had no effect on the amplitude or kinetics of GABA- or glutamate-mediated miniature postsynaptic currents (MPSCs) recorded in the presence of the Na+-channel blocker TTX (300 nM), indicating that the OP does not interact with GABA(A) or glutamate receptors. Further, sarin did not alter the frequency of GABAergic or glutamatergic MPSCs, a finding that led to the conclusion that this OP does not affect the TTX-insensitive release of neurotransmitters. A selective reduction by sarin of the action potential-dependent release of GABA in the hippocampus can account for the occurrence of seizures in intoxicated subjects.

Two tetrodotoxin-resistant sodium channels in human dorsal root ganglion neurons

Two tetrodotoxin-resistant (TTX-R) voltage-gated sodium channels, SNS and NaN, are preferentially expressed in small dorsal root ganglia (DRG) and trigeminal ganglia neurons, most of which are nociceptive, of rat and mouse. We report here the sequence of NaN from human DRG, and demonstrate the presence of two TTX-R currents in human DRG neurons. One current has physiological properties similar to those reported for SNS, while the other displays hyperpolarized voltage-dependence and persistent kinetics; a similar TTX-R current was recently identified in DRG neurons of sns-null mouse. Thus SNS and NaN channels appear to produce different currents in human DRG neurons.

Effects of the sodium channel blocker tetrodotoxin on acute white matter pathology after experimental contusive spinal cord injury

Focal microinjection of tetrodotoxin (TTX), a potent voltage-gated sodium channel blocker, reduces neurological deficits and tissue loss after spinal cord injury (SCI). Significant sparing of white matter (WM) is seen at 8 weeks after injury and is correlated to a reduction in functional deficits. To determine whether TTX exerts an acute effect on WM pathology, Sprague Dawley rats were subjected to a standardized weight-drop contusion at T8 (10 gm x 2.5 cm). TTX (0. 15 nmol) or vehicle solution was injected into the injury site 5 or 15 min later. At 4 and 24 hr, ventromedial WM from the injury epicenter was compared by light and electron microscopy and immunohistochemistry. By 4 hr after SCI, axonal counts revealed reduced numbers of axons and significant loss of large (>/=5 micrometer)-diameter axons. TTX treatment significantly reduced the loss of large-diameter axons. In addition, TTX significantly attenuated axoplasmic pathology at both 4 and 24 hr after injury. In particular, the development of extensive periaxonal spaces in the large-diameter axons was reduced with TTX treatment. In contrast, there was no significant effect of TTX on the loss of WM glia after SCI. Thus, the long-term effects of TTX in reducing WM loss after spinal cord injury appear to be caused by the reduction of acute axonal pathology. These results support the hypothesis that TTX-sensitive sodium channels at axonal nodes of Ranvier play a significant role in the secondary injury of WM after SCI.

Acute goby poisoning in southern Taiwan

Food poisoning due to ingestion of two fishes, Yongeichthys nebulosus and Sillago japonica, occurred in Kaohsiung, Taiwan, in February 1997. Two male persons (48 and 58 years old) were poisoned, with symptoms featured by dizziness, nausea, vomiting, numbness, and difficulty in respiration. All of the specimens of fish retained by the victims were combined and consisted of Yongeichthys nebulosus and Sillago japonica. These retained specimens were assayed for anatomical distribution of toxicity (as tetrodotoxin) and all specimens were found to be toxic. The highest toxicity of specimen was 7,650 mouse units (MU) in Y. nebulosus and 1,460 MU in S. japonica. However, the other specimens re-collected from that fish pier were also found to be highly toxic in Y. nebulosus, but nontoxic in S. japonica. Hence, Y. nebulosus was judged as the real causative fish in this food poisoning. The toxins were partially purified from the methanolic extracts of toxic fishes by ultrafiltration and Bio-Gel P-2 column chromatography. Cellulose acetate membrane electrophoresis and high performance liquid chromatography analyses demonstrated that tetrodotoxin was the causative agent of this food poisoning.