Prior cocaine self-administration does not impair the ability to delay gratification in rats during diminishing returns

Previous exposure to drugs of abuse produces impairments in studies of reversal learning, delay discounting and response inhibition tasks. While these studies contribute to the understanding of normal decision-making and how it is impaired by drugs of abuse, they do not fully capture how decision-making impacts the ability to delay gratification for greater long-term benefit. To address this issue, we used a diminishing returns task to study decision-making in rats that had previously self-administered cocaine. This task was designed to test the ability of the rat to choose to delay gratification in the short-term to obtain more reward over the course of the entire behavioral session. Rats were presented with two choices. One choice had a fixed amount of time delay needed to obtain reward [i.e. fixed delay (FD)], while the other choice had a progressive delay (PD) that started at 0 s and progressively increased by 1 s each time the PD option was selected. During the 'reset' variation of the task, rats could choose the FD option to reset the time delay associated with the PD option. Consistent with previous results, we found that prior cocaine exposure reduced rats' overall preference for the PD option in post-task reversal testing during 'no-reset' sessions, suggesting that cocaine exposure made rats more sensitive to the increasing delay of the PD option. Surprisingly, however, we found that rats that had self-administered cocaine 1-month prior, adapted behavior during 'reset' sessions by delaying gratification to obtain more reward in the long run similar to control rats.

The switch to balloon atrial septostomy with echocardiographic guidance--a severe complication

To warn about a severe complication of balloon atrial septostomy (BAS) guided by echocardiography, a retrospective review was undertaken of all BASs performed at Red Cross War Memorial Children's Hospital in Cape Town from 1984 to the end of 1992. BAS with fluoroscopy was carried out in 41 infants (group I). Since April 1991, 17 infants had BAS with two-dimensional echocardiography guidance in the intensive care unit (group II). The majority of patients (72%) had simple transposition of the great arteries. Only 3 patients in group I were catheterised via the umbilical vein (the remaining 38 via the femoral vein). In group II, 12 patients (71%) were catheterised via the umbilicus. The only fatality as a result of the procedure occurred in group II. This was the result of rupture of the splenic vein. The patient was catheterised via the umbilical vein, and echocardiography was not adequately used to guide the catheter below the diaphragm. There were no other severe complications in either group. Although echocardiographically guided BAS is easier, quicker, potentially safer and keeps the baby in a better homeostatic environment, we describe a severe complication of this procedure in the learning phase that has not been noted previously.

Why are some South African children with Down syndrome not being offered cardiac surgery?

About 1 in 1,000 children has Down syndrome. Extra chromosomal material results in a myriad of potential problems for the affected individual. About 40% of Down syndrome children will have cardiac abnormalities, ranging from the simple arterial duct to the complex atrioventricular septal defect. Virtually all these defects are amenable to surgical correction and extended survival is possible. In South Africa many of these children do not undergo cardiac surgery.

Anterograde transcatheter occlusion of the patent ductus arteriosus with Gianturco coils--a new, effective and inexpensive technique

OBJECTIVE

To report the use of Gianturco coils in non-surgical closure of patent ductus arteriosus (PDA).

DESIGN

Retrospective review of patient data.

SETTING

Two specialist paediatric cardiology units in Riyadh, Saudi Arabia, and Cape Town, South Africa.

PATIENTS

Thirty children (median age 36 months, weight 12.5 kg) and one adult (24 years old) with PDA underwent attempted transcatheter closure of the duct between August 1994 and February 1995.

OUTCOME MEASURES

Assessment of duct closure as measured angiographically or with colour flow Doppler techniques after insertion of a Gianturco coil or coils.

RESULTS

Total occlusion was achieved in 90% of patients. In 2 patients accidental embolisation of the coil occurred during the procedure. The coils were easily retrieved with a snare retrieval device. The median diameter of PDA occluded was 2.5 mm. Between 1 and 6 coils were used to achieve occlusion. The median procedure time was 79 minutes. Seventy-nine per cent of patients in Riyadh were handled as day cases.

CONCLUSION

Anterograde transcatheter occlusion of a small to moderate PDA with Gianturco coils is safe and effective. The technique is considerably less expensive than the Rashkind double umbrella.