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Biomedical subjects

S Hanna

Publications and source records attributed to S Hanna.

At least 19 recordsLinked to original sources
PubMed2007

Measuring children's participation in recreation and leisure activities: construct validation of the CAPE and PAC.

There is a need for psychometrically sound measures of children's participation in recreation and leisure activities, for both clinical and research purposes. This paper provides information about the construct validity of the Children's Assessment of Participation and Enjoyment (CAPE) and its companion measure, Preferences for Activities of Children (PAC). These measures are appropriate for children and youth with and without disabilities between the ages of 6 and 21 years. They provide information about six dimensions of participation (i.e. diversity, intensity, where, with whom, enjoyment and preference) and two categories of recreation and leisure activities: (i) formal and informal activities; and (ii) five types of activities (recreational, active physical, social, skill-based and self-improvement). This paper presents information about the performance of the CAPE and PAC activity type scores using data from a study involving 427 children with physical disabilities between the ages of 6 and 15 years. Intensity, enjoyment and preference scores were significantly correlated with environmental, family and child variables, in expected ways. Predictions also were supported with respect to differences in mean scores for boys vs. girls, and children in various age groups. The information substantiates the construct validity of the measures. The clinical and research utility of the measures are discussed.

Adolescent↗
PubMed2005

Calculation of the birefringences of nematic liquid crystals at optical and infrared wavelengths.

In this paper we critically examine computational methods for predicting the birefringences of nematic liquid crystals, with a view to screening molecules for potential use in infrared applications. Using the liquid-crystal 5CB as a test molecule, we calculate molecular electronic polarizabilities using ab initio quantum-mechanical techniques and a wide range of basis sets. We show that the polarizabilities tend to a limiting value as the quality of the basis set is improved. However, the biggest hurdle remains the determination of the refractive index from the polarizability data. We examine several methods for performing this conversion and conclude that the simplest equation, due to Vuks, is adequate for predicting the birefringence, given the uncertainties involved in other parameters. The agreement between calculation and experiment is best described as "semiquantitative." We perform similar calculations for a wide range of nematic liquid crystals at both 589 and 1550 nm, taking into account the likely impact of molecular vibrations at the longer wavelength. We demonstrate that there is a simple scale factor, for conventional nematics, between the birefringence at visible wavelengths and in the infrared. Thus knowledge of the birefringence at optical wavelengths, as widely available in the literature, is a good guide to the usefulness of conventional nematic liquid crystals as active elements for optical switching in the telecommunications industry.

Journal Article↗
PubMed2004

Neither baseline tests of molecular hypercoagulability nor D-dimer levels predict deep venous thrombosis in critically ill medical-surgical patients.

OBJECTIVE: Predicting patients who are harboring asymptomatic deep venous thrombosis (DVT), or who are at particular risk of developing DVT, is a desirable clinical goal since prevention or early treatment of DVT might reduce the risk of fatal pulmonary embolism. Thus validation of simple laboratory tests that reliably predict venous thromboembolism (VTE) would be clinically very important. Tests that might be useful for these applications include markers of hypercoagulability (predicting patients at risk of DVT) and D-dimer (predicting which patients may have acute DVT). METHODS: In a prospective cohort study we measured a panel of hypercoagulability markers at the time of ICU admission, and six commercial D-dimer assays were performed serially during the ICU stay in medical-surgical ICU patients who were screened for DVT with biweekly lower limb compression ultrasonography. Ultrasonography was also performed at the time of any clinically suspected DVT events. We matched cases with DVT with controls without DVT for length of stay in the ICU to generate receiver operating characteristics (ROC) curves. RESULTS: One hundred ninety-seven patients were enrolled. Blood was collected on a total of 763 occasions (median number of occasions per patient: 3, range 1-21). None of the assays predicted DVT, as indicated by the areas under the ROC curves, that did not differ significantly from 50%. CONCLUSION: In critically ill patients, neither tests of hypercoagulability nor D-dimer levels predict patients at risk of DVT and thus they should not be used to guide diagnostic testing for DVT.

Aged↗
PubMed2004

Evaluating children's rehabilitation services: an application of a programme logic model.

OBJECTIVES: To apply a programme logic model to evaluate the effectiveness of a new therapy service for children with special needs who were in transition from pre-school to kindergarten. SETTING: A children's outpatient rehabilitation centre in Ontario, Canada. MAIN OUTCOMES: The short-term outcomes included parents' perceptions of the transition process itself and the information they required, the children's skill development for the transition to kindergarten, and parents' perceptions of services and satisfaction with resources. METHODS: A combination of quantitative methods [Goal Attainment Scaling (GAS), Measure of Processes of Care (MPOC), Client Satisfaction Questionnaire (CSQ)] and qualitative interviews were used to evaluate both the process ('Outputs') and outcomes ('Short-term objectives') of the new therapy service. RESULTS: The children involved in the evaluation met or exceeded goals that were set by therapists and parents. Parents' perceptions of, and satisfaction with, the new service were higher than the provincial average. Qualitative data from interviews with parents and service providers supported the findings from standardized measures, and provided suggestions for future service delivery. CONCLUSIONS: The programme logic model provided researchers and service providers a collaborative and systematic approach to conducting programme evaluation in a relatively short-time frame. It appears to be a useful option for evaluation of other children's services.

Attitude to Health↗
PubMed2003

Factors affecting family-centred service delivery for children with disabilities.

BACKGROUND: The provision of family-centred services (FCS) emphasizes a partnership between parents and service providers so that families are involved in every aspect of services for their child. There is evidence that providing FCS is associated with improvements in parents' satisfaction with services, decreased parental stress, and positive child outcomes. METHODS: The purpose of this study was to examine factors that are most important in determining parent perceptions of the family centredness of care and parent satisfaction with service. A cross-sectional survey was completed by 494 parents, 324 service providers, and 15 CEOs from 16 organizations delivering children's rehabilitation services. Analyses were completed using a structural equation modelling approach. RESULTS: Survey return rates ranged from 77 to 94%. Findings indicate that the principal determinants of parent satisfaction with services are the family-centred culture at the organization and parent perceptions of FCS. Parent satisfaction with services was also influenced by the number of places where services were received and the number of health and development problems experienced by their child. CONCLUSION: Parent satisfaction with services is strongly influenced by the perception that services are more family centred, fewer places where services were received and fewer health and development problems for their child. Ways in which organizations can improve satisfaction through carrying out family-centred behaviours are discussed.

Attitude to Health↗
PubMed2003

Incidence of hyponatraemia and hyponatraemic seizures in severe respiratory syncytial virus bronchiolitis.

AIM: To document the incidence and early evolution of hyponatraemia (serum sodium < 136 mmol l(-1)) associated with respiratory syncytial virus (RSV) bronchiolitis in infants requiring intensive care. METHODS: In a retrospective review over two winter seasons, 130 infants were admitted with confirmed RSV infection, of whom 39 were excluded because of either pre-existing risk factors for hyponatraemia: diuretic therapy (n = 14), cardiac disease (n = 10), renal disease (n = 2) or lack of admission sodium data (n = 13). RESULTS: The incidence of admission hyponatraemia in the remaining infants (median age 6 wk) was 33% (30/91), with 11% (10/91) exhibiting a serum sodium less than 130 mmol l(-1) . Hyponatraemic and normonatraemic infants were of a similar age (median 6 vs 7 wk, p = 0.82). With fluid restriction and diuretic therapy, the incidence of hyponatraemia at 48 h had decreased to 3.3%, odds ratio 0.07 (95% confidence interval 0.02-0.24, p < 0.001). Four infants (4%) suffered hyponatraemic seizures at admission (sodium 114-123 mmol l(-1)); three had received hypotonic intravenous fluids at 100-150 ml kg(-1) d(-1) before referral to intensive care. All four were managed successfully with hypertonic (3%) saline, followed by fluid restriction, resulting in immediate termination of seizure activity and normalization of serum sodium values over 48 h. CONCLUSION: Hyponatraemia is common among infants with RSV bronchiolitis presenting to intensive care. Neurological complications may occur and fluid therapy in vulnerable infants should be tailored to reduce this risk.

Apnea↗
PubMed2003

Hypoalbuminaemia in critically ill children: incidence, prognosis, and influence on the anion gap.

AIMS: Hypoalbuminaemia has significance in adult critical illness as an independent predictor of mortality. In addition, the anion gap is predominantly due to the negative charge of albumin, thus hypoalbuminaemia may lead to its underestimation. We examine this phenomenon in critically ill children, documenting the incidence, early evolution, and prognosis of hypoalbuminaemia (<33 g/l), and quantify its influence on the anion gap. METHODS: Prospective descriptive study of 134 critically ill children in the paediatric intensive care unit (ICU). Paired arterial blood samples were taken at ICU admission and 24 hours later, from which blood gases, electrolytes, and albumin were measured. The anion gap (including potassium) was calculated and then corrected for albumin using Figge's formula. RESULTS: The incidence of admission hypoalbuminaemia was 57%, increasing to 76% at 24 hours. Neither admission hypoalbuminaemia, nor extreme hypoalbuminaemia (<20 g/l) predicted mortality; however, there was an association with increased median ICU stay (4.9 v 3.6 days). After correction for albumin the incidence of a raised anion gap (>18 mEq/l) increased from 28% to 44% in all samples (n = 263); this discrepancy was more pronounced in the 103 samples with metabolic acidosis (38% v 73%). Correction produced an average increase in the anion gap of 2.7 mEq/l (mean bias), with limits of agreement of +/-3.7 mEq/l. CONCLUSION: Admission hypoalbuminaemia is common in critical illness, but is not an independent predictor of mortality. However, failure to correct the anion gap for albumin may underestimate the true anion gap, producing error in the interpretation of acid-base abnormalities. This may have treatment implications.

Acid-Base Imbalance↗
PubMed2002

A comparison of three scoring systems for mortality risk among retrieved intensive care patients.

AIMS: To assess the impact of two paediatric intensive care unit retrieval teams on the performance of three mortality risk scoring systems: pre-ICU PRISM, PIM, and PRISM II. METHODS: A total of 928 critically ill children retrieved for intensive care from district general hospitals in the south east of England (crude mortality 7.8%) were studied. RESULTS: Risk stratification was similar between the two retrieval teams for scores utilising data primarily prior to ICU admission (pre-ICU PRISM, PIM), despite differences in case mix. The fewer variables required for calculation of PIM resulted in complete data collection in 88% of patients, compared to pre-ICU PRISM (24%) and PRISM II (60%). Overall, all scoring systems discriminated well between survival and non-survival (area under receiver operating characteristic curve 0.83-0.87), with no differences between the two hospitals. There was a tendency towards better discrimination in all scores for children compared to infants and neonates, and a poor discrimination for respiratory disease using pre-ICU PRISM and PRISM II but not PIM. All showed suboptimal calibration, primarily as a consequence of mortality over prediction among the medium (10-30%) mortality risk bands. CONCLUSIONS: PIM appears to offer advantages over the other two scores in terms of being less affected by the retrieval process and easier to collect. Recalibration of all scoring systems is needed.

Child↗
PubMed2001

Anti-inflammatory properties of molecular hydrogen: investigation on parasite-induced liver inflammation.

Molecular hydrogen reacts with the hydroxyl radical, a highly cytotoxic species produced in inflamed tissues. It has been suggested therefore to use gaseous hydrogen in a new anti-inflammatory strategy. We tested this idea, with the aid of the equipment and skills of COMEX SA in Marseille, a group who experiments with oxygen-hydrogen breathing mixtures for professional deep-sea diving. The model used was schistosomiasis-associated chronic liver inflammation. Infected animals stayed 2 weeks in an hyperbaric chamber in a normal atmosphere supplemented with 0.7 MPa hydrogen. The treatment had significant protective effects towards liver injury, namely decreased fibrosis, improvement of hemodynamics, increased NOSII activity, increased antioxidant enzyme activity, decreased lipid peroxide levels and decreased circulating TNF-alpha levels. Under the same conditions, helium exerted also some protective effects, indicating that hydroxyl radical scavenging is not the only protective mechanism. These findings indicate that the proposed anti-inflammatory strategy deserves further attention.

Animals↗
PubMed2000

An exploratory qualitative study examining the social and psychological processes involved in regular dental attendance.

OBJECTIVE: This study aimed to provide a description of the psychosocial process involved in regular dental attendance. METHODS: The study design was a qualitative cross-sectional study using unstructured and semistructured interviews and observations of regular dental visits. The study participants included 12 men and 18 women attending general dental practices and six men and four women attending an emergency dental service. The data were systematically recorded and subjected to line-by-line grounded theory coding around the main concerns of those attending the dentist. RESULTS: The main concern of those attending for a regular dental visit was checking their oral health. The six-month recall was conceptualized as a checking cycle in six phases: recalling, responding, inducing (i), waiting, inducing (ii), and telling. The possible outcomes of the cycle were maintaining oral health, sustaining oral health, and a further checking cycle. Variations in checking cycles resulted from reordering and normalizing pressures within participants' lifestyles. CONCLUSIONS: The findings of this study suggest that people's patterns of dental attendance are similar to those of other chronic illnesses. An understanding of the dynamic psychosocial processes involved in frequent dental attendance may be achieved when further research into this phenomenon is conducted.

Appointments and Schedules↗
PubMed1999

Infection of mice by a Toxoplasma gondii isolate from an AIDS patient: virulence and activation of hosts' immune responses are independent of parasite genotype.

Virulence of a Toxoplasma gondii isolate from an AIDS patient (designated as PTN) was compared with that of PLK, a variant of P-strain. Virulence was assessed in term of host survival upon inoculation in different strains of mice. All C57BL/6 mice died of acute toxoplasmosis by 7-10 days following intraperitoneal infection with 1 x 105 tachyzoites of PTN and 40% of BALB/c died on day 23 of infection, whereas 100% CBA/J infected with the same dose of PTN survived, as did outbred Swiss Webster mice. All C57BL/6, BALB/c, CBA/J, or Swiss Webster died of acute toxoplasmosis by 3-9 days postinfection upon inoculation with same dose of tachyzoites of the PLK strain. Further studies in CBA/J mice demonstrated that mice infected with PTN elicited a significantly higher lymphoproliferative response to crosslinked anti-CD3 mAb or Con A than PLK infected mice, and augmented production of TNFalpha, lower levels of nitrite and a higher number of NK cells. Genetical analysis indicated that both PLK and PTN strains of T. gondii are from type ll. Interestingly, being of the same genotype, the later showed less virulence upon inoculation in mice and had greater capacity to activate host immune system than the PLK strain.

AIDS-Related Opportunistic Infections↗
PubMed1999

Visualization of oxygen radical production in mouse liver in response to infection with Schistosoma mansoni.

BACKGROUND/AIMS: The tropical parasite S. mansoni induces granulomatous inflammation in the liver, following the lodging of eggs in this organ. In vitro studies suggested that the host's response might involve the production of oxygen radicals. METHODS: In an attempt to investigate the situation at the site of inflammation, under disease conditions, livers of infected mice were treated with dichlorodihydrofluorescein diacetate which fluoresces after oxidation. RESULTS: Fluorescence of the oxidized tracer revealed that oxygen radicals were produced by granulomatous inflammatory cells. The phenomenon reached its highest intensity close to the eggs. The membranes of the cells were strongly labelled, probably reflecting membrane-associated NADPH oxidase activity. The cytoplasm of hepatocytes was also fluorescent but with lower intensity; hepatocyte membranes or nuclei were not labelled. Fluorescence was reduced drastically by treatment with catalase and antioxidants, indicating the occurrence of H2O2. Treatment with superoxide dismutase had no effect. Neither the livers of uninfected animals nor those of infected animals before parasite egg deposition were labelled. Eosinophil peroxidase activity was released in the areas of inflammatory cells, but was not found in hepatocytes. CONCLUSIONS: The H2O2/peroxidase system, which is the cornerstone of the antimicrobial defense associated with inflammation, is activated in close contact with parasite eggs. The process does contribute to egg killing in vivo. Moreover, hepatocytes undergo oxidative stress in the entire organ. This finding is in agreement with the parasite-induced decrease of liver antioxidant defenses demonstrated previously.

Animals↗
PubMed1998

Principles for Sustainable Governance of the Oceans

Pressures being exerted on the ocean ecosystems through overfishing, pollution, and environmental and climate change are increasing. Six core principles are proposed to guide governance and use of ocean resources and to promote sustainability. Examples of governance structures that embody these principles are given.

Journal Article↗
PubMed1996

Engrailed gene dosage determines whether certain recessive cubitus interruptus alleles exhibit dominance of the adult wing phenotype in Drosophila.

The cubitus interruptus (ci) locus of Drosophila melanogaster is needed for normal development. Some mutants of this gene result in embryonic lethality, while others just disrupt adult wing veins. While undertaking a genetic screen for additional ci mutations that affect the wing veins, we recovered a modifier mutation on chromosome two that produced a ci phenotype in recessive ci heterozygotes (ci(recessive)/+). We identified the modifier mutation as an allele of engrailed and have called it engrailed-enhancer of cubitus interruptus (enEnci). As a double heterozygote (en-/+; ci-/+) this new en allele dominantly generates a ci wing vein phenotype. As a double heterozygote, it also enhances the ci wing vein phenotype of the dominant alleles ciW and ciCe2, but not ciD. Other loss-of-function en alleles also enhance the ci phenotype, with the en lethal alleles (and deletions) showing the strongest effect, while the homozygous viable en alleles show weaker enhancement. Strong en- alleles failed to induce a ci phenotype with heterozygotes of ci recessive lethal alleles l(4)13, l(4)17, or ciDrev, which are loss-of-function mutations. This supports a previous proposal that the ci wing vein phenotype is not due to loss of ci+ function, as would be expected for most recessive alleles. Instead, the adult wing vein abnormality is due to ectopic expression (or de-repression) of the ci transcript in the posterior compartment of the wing disc. We also observed that en-/+ heterozygotes could induce a ci phenotype in situations where the ci+ locus is either unpaired or hemizygous. Since loss of one en+ gene dose enhanced the ci phenotype, three doses of en+ were tested and found to suppress expression of the ci phenotype in ci1 homozygotes and ciW heterozygotes. These observations show that correct regulation of the ci gene involves more than the simple interaction of upstream regulatory elements. some pairing, pairing dependent gene repression, position effects.

Alleles↗
PubMed1993

Evidence of mobilization of hobo transposons in a P-element mutagenesis screen.

In Drosophila melanogaster, mutations in Su(var) and En(var) loci either suppress or enhance position effect variegation, respectively. Towards the cloning of these genes we have induced, recovered, and characterized a series of Su(var) mutations located on the third chromosome. These mutations were recovered from a P-element mutagenesis scheme in which the third chromosome P[ry+ delta 2-3](99B) element would provide transposase in trans to mobilize a single nonautonomous P transposon, P[pUCHSNeo](9C), located on the X chromosome. Although this cross scheme induces mobilization of the X-chromosome P transposons and its subsequent reinsertion onto the autosomes, none of the Su(var) mutations recovered could be associated with P-transposon insertions. Further investigation of these mutations by in situ hybridization showed that another mobile element that can be mobilized in hybrids, hobo, was associated with these mutations. We conclude that the mobilization and reinsertion of the hobo elements, through an inadvertent hybrid HE dysgenic cross, is most likely responsible for the Su(var) mutations recovered from this P-element mutagenesis. The association of hobo element with this Su(var) locus will facilitate its cloning and offers the possibility of hobo transposon tagging other Su(var) loci.

Animals↗