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P Joy

Publications and source records attributed to P Joy.

9 recordsLinked to original sources
PubMed2003

Natural history of cognitive deficits and their relationship to MRI T2-hyperintensities in NF1.

BACKGROUND: Cognitive impairment is the most common complication of neurofibromatosis type 1 (NF1) in childhood. Current research suggests a strong relationship between cognitive deficits and brain T2-hyperintensities. The majority of these lesions disappear as the child ages. Cross-sectional data suggest that there also are improvements in intellect. OBJECTIVE: To determine the natural history of cognitive functioning and MRI T2-hyperintensities from childhood into adulthood, and whether changes in MRI T2-hyperintensities over time are predictive of changes in cognitive functioning. METHODS: The authors conducted a prospective longitudinal study of a cohort of 32 patients with NF1 and 11 unaffected sibling controls. All patients underwent neuropsychological assessments and 27 children underwent MRI examinations. The patients were then reassessed after an 8-year period. RESULTS: and CONCLUSIONS: There was no improvement in cognitive ability as the children with NF1 developed into adulthood compared with controls. Despite significant decreases in the number, size, and intensity of the T2-hyperintensities over the 8-year period, these changes were not associated with changes in cognitive ability. T2-hyperintensities in the cortex or subcortical or deep white matter are more frequent with age and these lesions are likely to have a different pathology than basal ganglia lesions. The best predictor of cognitive dysfunction in adulthood was the presence of T2-hyperintensities in childhood, rather than current lesion status. There is a limited time window (<18 years) in which the presence of T2-hyperintensities can be used as biologic markers of cognitive dysfunction.

Adolescent↗
PubMed2000

Controlling gene expression in yeast by inducible site-specific recombination.

An intron module was developed for Saccharomyces cerevisiae that imparts conditional gene regulation. The kanMX marker, flanked by loxP sites for the Cre recombinase, was embedded within the ACT1 intron and the resulting module was targeted to specific genes by PCR-mediated gene disruption. Initially, recipient genes were inactivated because the loxP-kanMX-loxP cassette prevented formation of mature transcripts. However, expression was restored by Cre-mediated site-specific recombination, which excised the loxP-kanMX-loxP cassette to generate a functional intron that contained a single loxP site. Cre recombinase activity was controlled at the transcriptional level by a GAL1::CRE expression vector or at the enzymatic level by fusing the protein to the hormone-dependent regulatory domain of the estrogen receptor. Negative selection against leaky pre-excision events was achieved by growing cells in modified minimal media that contained geneticin (G418). Advantages of this gene regulation technique, which we term the conditional knock-out approach, are that (i) modified genes are completely inactivated prior to induction, (ii) modified genes are induced rapidly to expression levels that compare to their unmodified counterparts, and (iii) it is easy to use and generally applicable.

Attachment Sites, Microbiological↗
PubMed1998

Home nebulizer use among patients with cystic fibrosis.

OBJECTIVE: To describe current patterns of home nebulizer use among patients with cystic fibrosis. STUDY DESIGN: A population-based survey of home nebulizer practices among 227 patients with cystic fibrosis using nebulizers from 1993 to 1994 (Objective 1), and a prospective study of "typical" home use, including testing of performance and bacterial cultures in nebulizers after use, completed by 36 subjects (Objective 2). RESULTS: Objective 1: 85% of subjects reported using jet and 8% ultrasonic nebulizers (categories not mutually exclusive); 15% used unknown brands. Most jet nebulizers were disposable models, which were used for > 14 days by more than half the subjects. Mixing of medications in a single treatment (other than cromolyn and a bronchodilator) was reported by 28% of patients. Objective 2: no apparent deterioration in aerosol particle size or output rate of returned nebulizers compared with new units was observed. Staphylococcus aureus was cultured from 55% and Pseudomonas aeruginosa from 35% of returned nebulizers. Concordance between nebulizer and sputum cultures was poor. CONCLUSIONS: Although not generally tested for reusability, disposable nebulizers are generally used by patients for long periods. Medication mixing is common, although its effects on aerosol properties are unknown. Cystic fibrosis respiratory pathogens are frequently isolated from used nebulizers. Patient guidelines for home nebulizer use need to be established.

Child↗
PubMed1998

Effects of repetitive use and cleaning techniques of disposable jet nebulizers on aerosol generation.

STUDY OBJECTIVE: Patients with cystic fibrosis use disposable jet nebulizers for the self-administration of antibiotics, DNase, and bronchodilators several times per day. Most patients elect to reuse their disposable nebulizers. The purpose of this study was to determine if significant changes in particle size distribution or output (mL/min) occurred with reuse. DESIGN: In vitro studies were performed using four disposable models and one durable jet nebulizer for up to 100 runs; measurements of particle size and output were obtained at 10 run intervals, using saline solution alone, tobramycin, gentamicin, or a mixture of albuterol and cromolyn. Particle size determinations were made with a laser diffraction analyzer. RESULTS: There was no significant difference between the baseline performance of the four disposable models and the durable Pari LC, when measuring particle size distribution of the aerosol; the Pari LC had an output rate two to three times higher than the four disposable models. For each of the four solutes tested, there was no clinically significant change in performance for up to 100 cycles, when the nebulizers were properly cleaned between uses. Unwashed units containing tobramycin started to fail by 40 runs. CONCLUSIONS: When properly maintained, there was no trend of deterioration of performance with repeated use of disposable nebulizers. Microbial contamination was not addressed in this study and must be considered prior to recommendations for the reuse of disposable nebulizers.

Administration, Inhalation↗
PubMed1995

Neuropsychological function and MRI abnormalities in neurofibromatosis type 1.

This study investigated the relationship between MRI abnormalities and cognitive function in neurofibromatosis type 1.40 children aged eight to 16 years underwent comprehensive neuropsychological, medical and neuroradiological assessments. MRI scans revealed a characteristic pattern of T2-weighted signals ('UBOs') located primarily in the basal ganglia, brainstem and cerebellum in 25 of the children. Reductions in global IQ, attention, and visuopatial and executive functions were shown to occur in association with the presence of UBOs. These findings establish a link between changes in neuropsychological functions and MRI abnormalities in NF-1, and further support neuropathological findings which suggest that UBOs may be a manifestation of delayed or disordered myelination.

Adolescent↗
PubMed1995

Cognitive function and academic performance in children with neurofibromatosis type 1.

The authors evaluated 51 consecutive children with NF1 (aged eight to 16 years) to determine the frequency of intelectual impairment and learning disability due to NF1 alone, the profile of learning disabilities and the effect of clinical variables. 40 children completed the full assessment protocol. There was no support for a profile of predominantly visuoperceptual deficits in the NF1 population. There was no discrepancy between verbal and performance IQ, and the deficits in function were wide ranging. Clinical variables such as age, sex, socio-economic status, disease severity, macrocephaly and family history of NF1 were not associated with cognitive deficits. These results emphasise the need for developmental evaluation to be included in the routine assessment of children with NF1.

Adolescent↗
PubMed1994

Specific learning disability in children with neurofibromatosis type 1: significance of MRI abnormalities.

To determine whether previously reported areas of increased T2 signal intensity on MRI examination in children with neurofibromatosis type 1 (NF 1) are associated with deficits in development and learning common in this population, we evaluated 51 children with NF 1 (aged 8 to 16 years). Forty children completed the full assessment protocol (MRI, medical, psychometric, speech therapy, and occupational therapy assessments). The mean Full Scale IQ scores for the entire study population showed a left shift compared with the normal population, and the distribution of IQ scores was bimodal, suggesting that there are two populations of patients with NF 1--those with and those without a variable degree of cognitive impairment. There was no association between lower IQ scores and any clinical variable. Areas of increased T2 signal intensity unidentified bright objects (UBO+) were present in 62.5% of the study population, and their presence was not related to clinical severity, sex, age, socioeconomic status, macrocephaly, or family history of NF 1. However, compared with children without areas of increased T2 signal intensity (UBO-), the UBO+ group had significantly lower mean values for IQ and language scores and significantly impaired visuomotor integration and coordination. Children with areas of increased T2 signal intensity were at a much higher risk for impaired academic achievement. Children without increased T2 signal on MRI (UBO-) did not significantly differ from the general population in any measure of ability or performance. Areas of increased T2 signal on MRI represent dysplastic glial proliferation and aberrant myelination in the developing brain and are associated with deficits in higher cognitive function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
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Aged↗