No abstract

The prospect of being able to use "minimally invasive" surgical techniques is of great interest today, particularly for reasons of health economics, patient acceptability and reduced morbidity. High intensity focused ultrasound (HIFU) has long been known to offer the potential of very precise "trackless lesioning" but has only recently, with the advent of high quality methods of medical imaging, become a practicable possibility. High intensity beams can readily be achieved using either bowel or lens focusing procedures and, by choice of a suitable acoustic frequency, regions of tissue destruction--"lesions"--can be induced at depths of up to at least 10 cm with exposure times of the order of 1 s. Theoretical and experimental evidence indicates that the primary mechanism of damage is thermal, i.e. "cooking" of the tissues. Both conventional cavitation and boiling of tissue water may complicate the situation. Furthermore, substantial non-linear behaviour is involved. On histological appearance the lesions have a spatially sharp demarcation between regions of normal and dead cells. When attempts are made to ablate a block of tissue, by creating an array of adjacent elementary lesions, a phenomenon is observed of inhibition of formation of a lesion whose placing is too close to that of a neighbour. Provided that this problem is dealt with, complete ablation of an extended block of tissue can be achieved. For animal tumours in particular, this observation is reinforced by evidence both of in vitro cell survival and of tumour growth delay experiments. Clinically, the sites accessible for HIFU treatment will be limited by the need for a suitably wide acoustic window that either is available naturally or can be provided by a relatively minor surgical procedure. Tumour sites which thus offer a realistic prospect for local control (and some of which are already the subject of phase 1 trials) include liver, bladder, kidney, prostate, breast and brain. There is also considerable interest in non-cancer applications in these and other sites.

Mothers of children with Down syndrome, autism, and mixed etiology intellectual disabilities, matched on child age, gender, and communication skills (n = 19 in each group) completed measures of their child's adaptive and problem behaviors, their own parenting stress, and positive perceptions of their child. Children with autism were rated as having more problem behaviors and lower levels of social competence than children with Down syndrome and mixed etiology intellectual disabilities. Mothers of children with autism scored lower on positive perceptions of their child, and higher on stress than the other two groups. After selecting closely matched groups, we found several group differences in child behavior but little evidence of group differences in maternal outcomes.

The aims of this article were to test the psychometric properties of the Positive Contributions Scale (PCS), and to compare perceptions of positive contributions reported by mothers and fathers. Participants were 140 mothers and 60 fathers of children with intellectual disabilities. Results supported the reliability and construct validity of the PCS. Internal consistency was good for all subscales bar one, and the PCS total score was associated with scores on the Positive Affect Scale. There were differences on PCS scales for mothers and fathers, with mothers generally reporting more positive contributions than fathers. The PCS is a reasonably robust measure and its use in future research should help to address questions about the nature and function of parental positive perceptions. The PCS might also be used in applied settings to help balance the effects of asking families about their difficulties and support needs.