The stomatogastric ganglion (STG) of shellfish includes 30 neurons and produces pyloric rhythms. It is the common model to study central pattern generator (CPG). Regulation of pyloric rhythms not only is related to the property of single neurons in STG but also depends on the connections and property of the whole neuronal network. It has been found that transient potassium current (I(A)) and hyperpolarization-activated cation current (I(h)) exist in certain types of neurons of STG. However, roles played by these two currents in maintaining and regulating the pyloric rhythms are unknown. In the present study, in vitro electrophysiological recordings were performed on crayfish STG to examine the role played by I(A) and I(h) in regulation of pyloric rhythm. 4AP (2 mmol/L), a specific inhibitor of I(A), caused a decrease in pyloric cycle (P < 0.01), an increase in PD (pyloric dilator) ratio, a decrease in PY (pyloric) ratio (P < 0.01) and delay of phases of LP and PY firing. ZD7288 (100 μmol/L), a specific inhibitor of I(h), caused a decrease in pyloric cycle (P < 0.01), an increase in PD ratio (P < 0.01), an increase in LP (lateral pyloric) ratio (P < 0.01), a decrease in PY ratio (P < 0.01) and delay of phases of LP and PY firing. These results indicate that I(A) and I(h) play important roles in regulating pyloric rhythms in crayfish STG.
Animals ; Astacoidea ; cytology ; Ganglia, Invertebrate ; physiology ; Neurons ; cytology ; Pylorus ; innervation

While paleoparasitologists in Korea reported scientific evidences for the infection patterns of various parasite species among the pre-modern Joseon people, historical study is also needed for understanding the socio-cultural aspects of parasitic infections of the past. In this study on the historical documents, we revealed the socio-cultural environment of Joseon society by which people were easily infected by trematode parasites. The historical records showed that Joseon people enjoyed raw fish cuisines, that might have caused Clonorchis sinensis and Metagonimus yokogawai infection, much more frequently than originally expected. It is also proven that Joseon people ate raw crab and crayfish, the intermediate host of Paragonimus westermani, as the seasonal delicacy or miracle cure drug for incurable diseases. We also found many Joseon records on raw-oyster dishes, possibly having caused Gymnophalloides seoi infection among the people. By this study, we could get the historical clues on how Joseon people could have been infected by various trematode parasites.
Astacoidea ; Clonorchis sinensis ; Heterophyidae ; Korea ; Paragonimus westermani ; Parasites* ; Seasons

A case of cerebral paragonimiasis associated with right homonymous hemianopsia was reported in view of its rarity and a review of the related literaturs was made. The patient was 14 years old man. He had been suffering from poor visual acuity for 2 months and headache for 7 years. He had hsitory of indigestation of crayfish during measle infection. Skull x-ray revealed calcification on temporo-occipital region. He had been treated with bithionol, daily doses of 20mg/kg of body wt. for 70 days. And the rsult was improvement.
Adolescent ; Astacoidea ; Bithionol ; Headache ; Hemianopsia* ; Humans ; Paragonimiasis* ; Skull ; Visual Acuity

We have observed a case of the paragenimiasis involving epididymis which was complicated a part of systemic infection. The patient has complained painless nodular moderately hard mass in the right testicle and had a history of the raw crayfish ingestion during the course of measles. This was proved by the microscopic evidence which showed the granulomatoue lesion with round cell infiltration and necrotic debris and scattered eggs of the Paragonimus Westermani, also the adult worm was seen in the cystic space.
Adult ; Astacoidea ; Eating ; Eggs ; Epididymis* ; Humans ; Male ; Measles ; Ovum ; Paragonimiasis* ; Paragonimus westermani ; Testis

Paragonimiasis mainly occurs by ingestion of raw or undercooked freshwater crabs or crayfish. In our country, the prevalence of paragonimiasis was high until late 1960s due to eating habits, but after the 1970s the prevalence of the disease has markedly decreased and now the disease is rarely seen. As the clinical and radiological features as well as the laboratory findings are similar to that of pulmonary tuberculosis, the differential diagnosis of pulmonary paragonimiasis is very difficult. We experienced a case of a patient with pulmonary paragonimiasis who was treated as having pulmonary tuberculosis.
Astacoidea ; Diagnosis, Differential ; Eating ; Fresh Water ; Humans ; Paragonimiasis* ; Prevalence ; Tuberculosis ; Tuberculosis, Pulmonary*

Paragonimiasis is a parasitic infection that occurs following the ingestion of infectious Paragonimus metacercariae, which occurs as a result of eating raw or undercooked freshwater crabs or crayfish. Pulmonary paragonimiasis is the most common clinical manifestation of this infection. Human paragonimiasis occurs sporadically. We experienced a case of pulmonary paragonimiasis in a 35-year-old woman with left lower chest pain. The patient had hypereosinophilia and a pleural effusion. The diagnosis was confirmed by positive ELISA (Enzyme-linked immunosorbent assay) that detected Paragonimiasis westermani antibody in the serum. We treated the patient with praziquantel for two days at a daily dosage of 75 mg/kg. Left pleuritic pain and pleural effusion improved after treatment. However, similar symptoms and pleural effusion developed recurrently for the first 3 courses of treatment with praziquantel. Upon the fourth round of treatment, the patient made a full recovery.
Adult ; Astacoidea ; Chest Pain ; Eating ; Enzyme-Linked Immunosorbent Assay ; Female ; Fresh Water ; Humans ; Metacercariae ; Paragonimiasis ; Paragonimus ; Pleural Effusion ; Praziquantel ; Recurrence

Paragonimiasis is an infection caused by the tematode Paragonimus westermani. Paragonimiasis is endemic in parts of South America, Africa, East and Southest Asia. Human infection occurs by ingestion of raw or incompletely cooked flesh crabs or crayfish infected with metacercaria. Although the lung is the primary site of infection, other organs, notably the brain, may be involved. It rarely affects in abdomen. However, involvement of several intra-abdominal organs has been described. In our knowledge, an ectopic paragonimiasis in prevesical space mimicking urachal cystic mass has not been reported. In this report, we present a case of ectopic paragonimiasis mimicking urachal cystic mass in 66-year-old male.
Abdomen ; Africa ; Aged ; Asia ; Astacoidea ; Brain ; Eating ; Humans ; Lung ; Male ; Paragonimiasis* ; Paragonimus westermani ; South America ; Urachal Cyst*

The present study investigated the infection status of Paragonimus westermani metacercariae in freshwater crabs (n = 363) and crayfish (n = 31) from October 2007 to October 2008 using the crush method. All of the freshwater crabs, Eriocheir japonicus, were negative for P. westermani metacercariae while 10 (32.3%) of the 31 examined crayfish were positive. The 10 positive crayfish were caught in Haenam, Jeollanam-do, and there were 8-59 (mean 28.4) metacrcariae per infected crayfish. These results suggest that P. westermani metacerariae are still transmitted by crayfish enzootically in southern Korea, and that freshwater crabs may transmit metacercariae only on rare occasions.
Animals ; Astacoidea/*parasitology ; Brachyura/*parasitology ; Humans ; Korea/epidemiology ; Paragonimiasis/epidemiology/parasitology/*veterinary ; Paragonimus westermani/*isolation & purification ; Prevalence

An epidemiological study was performed to know the recent infection status of Paragonimus westermani metacercariae (PwMc) in freshwater crayfish, Cambaroides similis, from 2 streams in Jeollanam-do, Republic of Korea. Crayfish were collected from creeks in Bogil-do (Island), Wando-gun, and in a creek near Daeheung Temple in Haenam-gun. The infection rate of crayfish with PwMc in Bogil-do was 89.8%, and the metacercarial burden was 37 PwMc per the infected crayfish. Crayfish in a creek near Daeheung Temple were larger and twice heavier than those in Bogil-do. Of them, 96.5% were infected with PwMc. An average of 140 metacercariae was found in the infected crayfish, almost quadruple to those of Bogil-do. There was a strong correlation between the number of PwMc and body weight of the crayfish. These results suggest that P. westermani metacercariae are still prevalent in crayfish of the 2 regions in Jeollanam-do, Korea.
Astacoidea* ; Body Weight ; Epidemiologic Studies ; Fresh Water* ; Incidence* ; Jeollanam-do* ; Korea* ; Metacercariae* ; Paragonimus westermani* ; Paragonimus* ; Republic of Korea ; Rivers

The purpose of this study is to identify the electrical activity of neuron, the existence of the transition from bursting pattern to spiking pattern and the ion mechanism of the bursting pattern. The intracellular electrical activity patterns of single neurons in the stomatogastric ganglion (STG) of crayfish were recorded when the extracellular calcium concentration ([Ca(2+)](o)) or calcium-dependent potassium channel blocker tetraethylammonium concentration ([TEA](o)) were changed, using intracellular recording method. These single neurons were also functionally isolated from the ganglion by application of atropine and picrotoxin which could block the inhibitory acetylcholine synapses and glutamatergic synapses respectively. When [Ca(2+)](o) was decreased by increasing EGTA, the membrane potential of the neuron was increased, and the electrical activity patterns were changed from the resting state with lower potential value (resting state of polarization) to the bursting pattern firstly, and then to the spiking pattern, at last to the resting state with higher potential value (resting state of depolarization). When [TEA](o) was increased, the membrane potential of the neuron was increased, and the electrical activity pattern was changed from the resting state with lower potential value (resting state of polarization) to the bursting pattern firstly, and then to the spiking pattern. The duration of the burst of the bursting pattern was increased. When [Ca(2+)](o) was increased or [TEA](o) was decreased, an inverse procedure of the electrical activity pattern was exhibited. On one hand, the results indicate that a single neuron can generate various electrical activity patterns corresponding to different physiological conditions, and the regularity of the transitions between different electrical activity patterns. On the other hand, the results identify that the initiation and termination of the burst in bursting pattern are determined by calcium-activated potassium conductance, which is adjusted by intracellular calcium concentration influenced by inward calcium current. It may be the ionic mechanism of generation of the bursting pattern in a single neuron.
Action Potentials ; physiology ; Animals ; Astacoidea ; physiology ; Calcium ; metabolism ; Calcium Channels ; metabolism ; Ganglia, Invertebrate ; physiology ; Neurons ; physiology ; Potassium Channels, Calcium-Activated ; metabolism