Trace fear conditioning is characterized by a stimulus-free trace interval (TI) between the conditioned stimulus (CS) and the unconditioned stimulus (US), which requires an array of brain structures to support the formation and storage of associative memory. The entorhinal cortex (EC) has been proposed to provide essential neural code for resolving temporal discontinuity in conjunction with the hippocampus. However, how the CS and TI are encoded at the neuronal level in the EC is not clear. In Exp. 1, we tested the effect of bilateral pre-training electrolytic lesions of EC on trace vs. delay fear conditioning using rats as subjects. We found that the lesions impaired the acquisition of trace but not delay fear conditioning confirming that EC is a critical brain area for trace fear memory formation. In Exp. 2, single-unit activities from EC were recorded during the pretraining baseline and post-training retention sessions following trace or delay conditioning. The recording results showed that a significant proportion of the EC neurons modulated their firing during TI after the trace conditioning, but not after the delay fear conditioning. Further analysis revealed that the majority of modulated units decreased the firing rate during the TI or the CS. Taken together, these results suggest that EC critically contributes to trace fear conditioning by modulating neuronal activity during the TI to facilitate the association between the CS and US across a temporal gap.

BACKGROUND AND OBJECTIVES: Primary (idiopathic) pulmonary hypertension is a rare, progressive and fatal disease. It has been defined, by the World Health Organization, as a mean pulmonary arterial pressure greater than 25 mmHg at rest, or greater than 30 mmHg during exercise, without the apparent cause of secondary pulmonary hypertension. This study was performed to better understanding the clinical presentation, natural history and prognosis of primary pulmonary hypertension. SUBJECTS AND METHODS: A total of 18 patients, who were diagnosed as primary pulmonary hypertension, at three University Hospitals, were retrospectively reviewed. All patients had undergone echocardiography and cardiac catheterization. RESULTS: With the patients there was a male: female ratio of 1:8, ranging in age between 10 and 50 years. The most common presenting symptom was dyspnea on exertion, with other symptoms comprising of fatigue in 11, chest pain in 5, syncope in 3 and hemoptysis in 2. The ECG & echocardiography reflected the presence of right-sided heart enlargement. The average right ventricular systolic pressure, from Doppler echocardiography, was 73.6+/-18.8 mmHg. The mean pulmonary artery pressure and pulmonary capillary wedge pressure were 52.9+/-18.4 and 9.2+/-3.1 mmHg, respectively. The survival times were within 30 and 21 to 60 months in 9 and the remaining patients, respectively. CONCLUSION: We conclude that primary pulmonary hypertension is common in female patients in their third to fifth decades. This study also showed a poor prognosis, as in other reports.
Arterial Pressure ; Blood Pressure ; Cardiac Catheterization ; Cardiac Catheters ; Cardiomegaly ; Chest Pain ; Dyspnea ; Echocardiography ; Echocardiography, Doppler ; Electrocardiography ; Fatigue ; Female ; Hemoptysis ; Hospitals, University ; Humans ; Hypertension, Pulmonary* ; Male ; Natural History ; Prognosis ; Pulmonary Artery ; Pulmonary Wedge Pressure ; Retrospective Studies ; Syncope ; World Health Organization

Rupture of the interventricular septum is a serious complication of acute myocardial infarction, accounting for 5% of death due to acute myocardial infarction. The mortality with medical therapy alone exceeds 90%. Accurate diagnosis, urgent management, and early operative correction are necessary for survival. We report cases of 3 patients with ventricular septal rupture after acute myocardial infarction.
Diagnosis ; Humans ; Mortality ; Myocardial Infarction* ; Rupture ; Ventricular Septal Rupture*

Cardiac metastases of renal cell carcinomas are rare, and usually clinically silent. A case of a 53-year-old man without a significant medical history, who presented with ventricular tachycardia, which resulted in a cardiac mass of the right ventricle is reported. On chest X-ray, echocardiography, CT scanning, esophagogastroduode-noscopy and MRI, multiple metastatic masses were observed in both lungs, and the kidneys, adrenal, stomach and right ventricle. The kidney mass and the gastric polyp were revealed on biopsy to be a renal cell carcinoma mixed with sarcomatoid and conventional types.
Adult* ; Biopsy ; Carcinoma, Renal Cell* ; Echocardiography ; Heart Ventricles ; Humans ; Kidney ; Lung ; Magnetic Resonance Imaging ; Middle Aged ; Neoplasm Metastasis ; Polyps ; Stomach ; Tachycardia, Ventricular* ; Thorax ; Tomography, X-Ray Computed