Right ventricular outflow tract obstruction in an older woman: facilitated diagnosis with transesophageal echocardiography-guided biopsy.

Fibrosarcoma is a rare primary cardiac malignancy. We report the case of a 70-year-old woman who had signs of right ventricular outflow tract obstruction caused by a fibrosarcoma. The pivotal role of multiplanar transesophageal echocardiography in characterizing masses in this location and in guiding transvenous biopsy is discussed.

Quantitative and qualitative aspects of the hibernation-related reduction of morphine physical dependence in the ground squirrel (Citellus lateralis).

The development of morphine physical dependence in the contrasting brain states of the nonhibernating (NH) vs. the hibernating (H) condition was measured in the ground squirrel hibernator Citellus lateralis. Morphine was infused continuously into the lateral ventricle (3.44, 6.88 and 13.75 micrograms/hr for periods of 1, 3 and 6 days) in NH and H animals, followed by measurement of the naloxone (1 mg/kg s.c.) evoked abstinence syndrome during the NH state (i.e., H animals were tested after arousal to the NH state). The results showed that morphine treatment during the NH state resulted in significant naloxone-evoked abstinence and an overall dose- and duration-related increase in the strength of the abstinence syndrome. By contrast, morphine treatment during hibernation resulted in significantly reduced abstinence compared with that observed after treatment during the NH state, with no significant morphine dose-response or duration-response trends evident. However, H-state morphine treatment did produce a dose-related reduction of hibernation bout duration. The reduction in the strength of dependence during the H state was associated with a qualitative change in the abstinence syndrome, as revealed by exploratory factor analysis. This change was reflected by an approximate reversal of the rank order of abstinence signs. These results demonstrate that hibernation-related changes in central nervous system function significantly reduce the liability for and change the character of the development of morphine dependence.

Morphine physical dependence in the hibernator: central nervous system mechanisms underlying the development of dependence remain functional during depression induced by pentobarbital anesthesia.

Earlier work suggested that adaptive mechanisms of the hibernating brain may also block the development of morphine physical dependence. To test an alternate view that CNS depression itself might be the major factor in the failure of dependence to develop, we compared the strength of dependence produced by morphine (two 75-mg pellets, s.c.) given for 12 hr in the presence, versus in the absence, of continuous pentobarbital anesthesia in nonhibernating ground squirrels (Citellus lateralis) and, in addition, in rats. Dependence was measured by the naloxone (5 mg/kg, s.c.) evoked abstinence syndrome in the awake state. The results demonstrated that pentobarbital-induced general anesthesia does not significantly reduce the development of morphine dependence in either species. We conclude that CNS depression alone does not account for the hibernation-related reduction in morphine physical dependence.