Mitochondrial inheritance in Schistosoma mansoni: mitochondrial variable number tandem repeat mutation produces noise on top of the signal.

The Schistosoma mansoni mitochondrial genome contains tandemly arrayed copies of a 62-base repeat motif. The tandem array is highly polymorphic with respect to number of repeats and commonly exhibits heteroplasmy. This study shows that a very high rate of mutation rapidly produces new repeat lengths (new haplotypes) for this mitochondrial variable number tandem repeat. A maternal inheritance pattern is also demonstrated for this repeat sequence, while the high mutation rate causes some offspring to exhibit nonmaternal haplotypes. Frequent generation of new haplotypes can be observed within samples of clonal cohorts taken from monomiracidial snail infections. These same clonal cercarial groups, when crossed, produce F1 generations that exhibit the maternal set of haplotypes, across all individuals, with the frequent addition of new mutant haplotypes. In each of 2 crosses, a subset of the recently arisen haplotypes match paternal haplotypes by chance (30.4% and 18.8%), thus giving the false appearance of partial paternal inheritance of mitochondria.

A survey of pain services for pediatric oncology patients: their composition and function.

The purpose of this survey was to examine the composition and function of pain services/teams at facilities that provide pain management services to pediatric oncology patients across the United States. A questionnaire was mailed to facilities identified by the 1994 Pain Facilities Directory as providing pain services to cancer patients. Thirty-five facilities that identified oncology patients as one of the primary pediatric populations treated at their institution were the focus of this study. Eight facilities that managed bone marrow aspirations and/or lumbar punctures for pediatric oncology patients also participated in a telephone interview regarding analgesia/sedation practices for procedure-related pain. Provision of direct patient care was a primary function of the pain services surveyed, although delivery of services varied across settings. Postoperative and chronic pain were the most frequent reasons for referral. Only 17% and 3% of facilities had established written standard guidelines for pharmacological and nonpharmacological approaches to pain management, respectively. Most facilities reported using a local anesthetic and conscious sedation to manage bone marrow aspiration and lumbar punctures. Implications from these findings and recommendations for provision of pediatric pain services are discussed.

Children's willingness to share activities with a physically handicapped peer: am I more willing than my classmates?

OBJECTIVE: To examine factors affecting children's willingness to share activities with a peer presented as physically handicapped. METHOD: Participants were 120 elementary school children randomly assigned to view a video of an ambulatory child or the same child in a wheelchair. They rated, on the Shared Activities Questionnaire (SAQ), their own willingness (SAQ-Self) and their perceptions of classmates' willingness (SAQ-Others) to participate in activities with the child. RESULTS: SAQ-Self ratings were consistently higher for the peer in the wheelchair. On the SAQ-Others, differences favoring the child in the wheelchair disappeared, and ratings of this child were lower than SAQ-Self ratings. No interactions were found between ambulation status and age or rater gender or preference for type of shared activity. CONCLUSIONS: Children showed highly positive intentions toward a peer in a wheelchair, but intentions attributed to classmates were less positive, which suggests "social desirability" influenced their own ratings.

Quantitative MRI of the brain in children with sickle cell disease reveals abnormalities unseen by conventional MRI.

Conventional MRI (cMRI) has shown that brain abnormalities without clinical stroke can manifest in patients with sickle cell disease (SCD). We used quantitative MRI (qMRI) and psychometric testing to determine whether brain abnormalities can also be present in patients with SCD who appear normal on cMRI. Patients 4 years of age and older with no clinical evidence of stroke were stratified by cMRI as normal (n = 17) or abnormal (n = 13). Spin-lattice relaxation time (T1) of gray and white matter structures was measured by the precise and accurate inversion recovery (PAIR) qMRI method. Patient cognitive ability was assessed with a standard psychometric instrument (WISC-III or WISC-R). In all 30 patients with SCD, qMRI T1 was lower than in 24 age- and race-matched controls, in cortical gray matter (P < .0006) and caudate (P < .0009), as well as in the ratio of gray-to-white matter T1 (P < .008). In the 17 patients who were shown to be normal by cMRI, qMRI T1 was still lower than in controls, in both cortical gray matter (P < .02) and caudate (P < .004). Histograms of voxel T1 show that the proportion of voxels with T1 values intermediate between gray and white matter (ie, consistent with encephalomalacia) was 9% higher than controls in patients shown to be normal by cMRI (P < .05) and 15% higher than controls in patients shown to be abnormal by cMRI (P < .0005). The full scale intelligence quotient (FSIQ) of all patients with SCD was 75, compared to the FSIQ of 88 in a historical control group of patient siblings (P < .001). The FSIQ of patients shown to be normal by cMRI was 79, significantly lower than the FSIQ of patient siblings (P < .04). The FSIQ of 71 in patients shown to be abnormal by cMRI was significantly lower than both the patient siblings (P < .005) and the patients shown to be normal by cMRI (P < .04). Patients shown to be abnormal by cMRI scored lower than patients shown to be normal by cMRI, specifically on the subtests of vocabulary (P = .003) and information (P = .03). Cognitive impairment is thus significant, even in patients with SCD who were shown to be normal by cMRI, suggesting that cMRI may be insensitive to subtle neurologic damage that can be detected by qMRI. Because cognitive impairment can occur in children normal by cMRI, our findings imply that prophylactic therapy may be needed earlier in the course of SCD to mitigate neurologic damage.

Anticipatory nausea and vomiting in pediatric cancer patients: an analysis of conditioning and coping variables.

We examined the influence of cognitive factors and conditioning variables on anticipatory nausea and vomiting symptoms (ANV) in 32 pediatric cancer patients with postchemotherapy nausea and vomiting (PNV) who received ondansetron. The patients were compared with 18 patients without ANV (NANV). Age, gender, history of motion sickness, aggressiveness of the chemotherapy, PNV severity, number of chemotherapy treatments, number, type, and efficacy of self-reported coping strategies, and expectations of severity of postchemotherapy symptoms failed to differentiate the ANV and NANV groups. The amount of subjective distress associated with nausea and vomiting was significantly greater in the ANV group. Among patients in whom ANV developed, level of distress and expectations of severity of postchemotherapy symptoms were positively correlated with the severity of ANV and PNV symptoms. Therefore, greater distress might increase the likelihood of ANV conditioning. Once ANV is conditioned, cognitive factors might influence the severity of symptoms.

Variables associated with anticipatory nausea and vomiting in pediatric cancer patients receiving ondansetron antiemetic therapy.

Investigated the prevalence of anticipatory nausea and vomiting (ANV) among 59 pediatric cancer patients who had routinely received ondansetron (Zofran) antiemetic therapy and determined patient- and treatment-related factors associated with ANV. Of the sample, 59% indicated at least mild ANV symptoms, suggesting that a significant number of patients report ANV and are bothered by it, despite the use of Zofran. These children were compared to those reporting no ANV symptoms. Most ANV symptomatology was consistent with a traditional classical conditioning model although cognitive processes may also play a role. Children with greater expectations of severe postchemotherapy vomiting and those who were more distressed by nausea and vomiting were more likely to experience ANV symptoms. Implications for psychological and pharmacological treatments of ANV are discussed.