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Biomedical subjects

L Young

Publications and source records attributed to L Young.

At least 19 recordsLinked to original sources
PubMed2006

X-ray microprobe of orbital alignment in strong-field ionized atoms.

We have developed a synchrotron-based, time-resolved x-ray microprobe to investigate optical strong-field processes at intermediate intensities (10(14) - 10(15) W/cm2). This quantum-state specific probe has enabled the direct observation of orbital alignment in the residual ion produced by strong-field ionization of krypton atoms via resonant, polarized x-ray absorption. We found strong alignment to persist for a period long compared to the spin-orbit coupling time scale (6.2 fs). The observed degree of alignment can be explained by models that incorporate spin-orbit coupling. The methodology is applicable to a wide range of problems.

Journal Article↗
PubMed2006

Outcomes in African Americans and Hispanics with lupus nephritis.

Poor outcomes have been reported in African Americans and Hispanics compared to Caucasians with lupus nephritis. The purpose of this retrospective analysis was to identify independent predictors of outcomes in African Americans and Hispanics with lupus nephritis. In total, 93 African Americans, 100 Hispanics, and 20 Caucasians with a mean age of 28 +/- 13 years and an annual household income of 32.9 +/- 17.3 (in 1000 US dollars) were studied. World Health Organization (WHO) lupus nephritis classes II, III, IV, and V were seen in 9, 13, 52, and 26%, respectively. Important baseline differences were higher mean arterial pressure (MAP) in African Americans compared to Hispanics and Caucasians (107 +/- 19, 102 +/- 15, and 99 +/- 13 mmHg, P < 0.05), and higher serum creatinine (1.66 +/- 1.3, 1.25 +/- 1.0, and 1.31 +/- 1.0 mg/dl, P < 0.025). African Americans had lower hematocrit compared to Hispanics and Caucasians (29 +/- 5, and 31 +/- 6, and 32 +/- 7%, P < 0.05), and lower annual household income (30.8 +/- 14.9, 33.1 +/- 15.9, and 42.2 +/- 29.3 in 1000 US dollars; P < 0.05). Lower prevalence of WHO class IV was seen in Caucasians (30%) compared to Hispanics (57%, P = 0.03) and African Americans (51%, P = 0.09). Development of doubling creatinine or end-stage renal disease was higher in African Americans and Hispanics than in Caucasians (31, 18, and 10%; P < 0.05), as was the development of renal events or death (34, 20, and 10%; P < 0.025). Our results suggest that both biological factors indicating an aggressive disease and low household income are common in African Americans and Hispanics with lupus nephritis, and outcomes in these groups are worse than in Caucasians.

Adolescent↗
PubMed2006

Community and cluster centre residential services for adults with intellectual disability: long-term results from an Australian-matched sample.

BACKGROUND: Changes in residential accommodation models for adults with intellectual disability (ID) over the last 20 years in Australia, the United Kingdom and the United States have involved relocation from institutions primarily into dispersed homes in the community. But an evolving alternative service style is the cluster centre. METHODS: This paper reports on the relocation of a matched group of 30 pairs of adults with moderate and severe IDs and challenging behaviour who were relocated from an institution into either dispersed housing in the community or cluster centres but under the same residential service philosophy. Adaptive and maladaptive behaviour, choice-making and objective life quality were assessed prior to leaving the institution and then after 12 and 24 months of living in the new residential model. RESULTS: Adaptive behaviour, choice-making and life quality increased for both groups and there was no change in level of maladaptive behaviour compared with levels exhibited in the institution. However, there were some significant differences between the community and cluster centre group as the community group increased some adaptive skills, choice-making and objective life quality to a greater extent than the cluster centre group. CONCLUSIONS: Both cluster centre and dispersed community living offer lifestyle and skill development advantages compared with opportunities available in large residential institutions. Dispersed community houses, however, offer increased opportunities for choice-making, acquisition of adaptive behaviours and improved life quality for long-term institutionalized adults with IDs.

Activities of Daily Living↗
PubMed2006

Post-treatment residual thrombus increases the risk of recurrent deep vein thrombosis and mortality.

BACKGROUND: Recurrent thromboembolic events after an initial deep vein thrombosis (DVT) are relatively frequent. Residual thrombus in the affected veins on ultrasound scan at the completion of anticoagulant therapy has been described as a recurrence risk factor, and may have utility in stratifying those patients at risk. OBJECTIVES: The aims of the study were to correlate the risk of recurrence of DVT with the results of ultrasound at completion of oral anticoagulant therapy. A secondary aim was to review the mortality in this population. PATIENTS: A cohort of 316 DVT patients was included. The patients were divided into those with completely clear vessels on follow-up scan (45%) and those with residual thrombus identified (55%). RESULTS: The cumulative incidence of recurrence was 10% by 2 years and 23% by 5 years. Patients with residual thrombus on follow-up ultrasound were at higher risk of recurrence (hazard ratio [HR] 2.2, 1.19-4.21; P = 0.012) which remained significant after multivariate adjustment for age, gender and malignancy (HR 2.2, 1.15-4.17; P = 0.018). During follow-up, the cumulative mortality was 12% at 2 years and 27% by 5 years. The risk of death was increased in patients with residual thrombus on follow-up scan (HR 3.9, 1.93-7.71; P < 0.001) and this risk persisted after multivariate analysis of age, gender and malignancy (2.8, 1.37-5.72; P = 0.005). The majority of deaths were due to malignancy (68%) however 10 (18%) died from vascular causes. There was a trend towards increased vascular death in the patients with residual thrombus on follow-up ultrasound scan, which did not reach significance (HR 4.1, 0.87-19.33; P = 0.13). CONCLUSIONS: Consistent with previous cohort studies, recurrence risk is increased in patients with residual thrombus on ultrasound. The increased risk of death in patients with residual thrombus, with a trend towards increased vascular death, may suggest that failure of thrombus resolution is a marker of more global vascular dysfunction.

Anticoagulants↗
PubMed2006

Developing capacity to protect human research subjects in a post-conflict, resource-constrained setting: procedures and prospects.

The capacity-building strategy used by a US-based research organisation, the Pacific Institute for Research and Evaluation (PIRE), to strengthen the system for the protection of human research subjects and the infrastructure of its international collaborating partner, the University of Liberia, are discussed. To conduct the much-needed biomedical and social science-based research-related activities in the future, this partnership is expected by PIRE to gradually evolve over time to strengthen the capacity of the local investigators and administrators of the University of Liberia. Accordingly, a unique opportunity to share technology and resources with a post-conflict, resource-constrained country is created by this partnership. This capacity-building model to strengthen the protection of human subjects in research can also be replicated in similar resource-constrained international settings and, accordingly, our experiences and limitations are shared in this paper.

Culture↗
PubMed2006

Choline supplementation facilitates short-term memory consolidation into intermediate long-term memory of young Sprague-Dawley rats.

Choline is important for the synthesis of acetylcholine, an integral neurotransmitter involved in memory formation. In order to investigate the effect of choline supplementation on memory consolidation, the study utilized a T-maze to facilitate passive avoidance learning and memory in young female Sprague-Dawley rats. Rats were placed in two groups; choline-supplemented that received choline chloride daily for two weeks, and control that received vehicle daily for two weeks. Rats were evaluated to determine their ability to avoid an aversive electric foot-shock (0.1 mA at 60V) when they characteristically entered the preferred dark area (DA) of the T-maze. Both groups of rats showed preference, without significant difference, for entry into DA of the T-maze. However, fifteen minutes after passive avoidance both choline supplemented and control rats avoided entry into DA. This display of DA avoidance 15 minutes after training, suggests that both groups of rats had acquired short-term memory of the aversive stimulus. However, when the test was repeated 24 hours after training, the control group did not avoid entry into DA, whereas the choline-supplemented group either avoided entry or entered after a significantly longer latency period (p < 0.01). These results suggest that supplementation with choline facilitated the consolidation of short-term memory of the avoidance learning into intermediate long-term memory in young rats.

Age Factors↗
PubMed2005

Targeting an MMP-9-activated prodrug to multiple myeloma-diseased bone marrow: a proof of principle in the 5T33MM mouse model.

Multiple myeloma (MM) is an incurable B-cell cancer characterised by the monoclonal proliferation of tumour cells in the bone marrow (BM). It has been described that matrix metalloproteinases (MMPs) and especially MMP-9 is secreted by MM cells. In this study, we investigated the possibility to exploit MMP-9 activity to activate prodrugs and to target MM cells as a new tumour-specific therapy. Cleavage of the prodrug EV1-FITC by MMP-9 resulted in release of fluorescence which can be used as a measure of prodrug activation. The 5T33MM mouse model was used in this proof-of-principle study. The prodrug was activated in a higher amount by addition to MMP-9-producing 5T33MMvv cells, homogenates from tumour-bearing organs (BM, spleen) and isolated 5T33MM-diseased BM and spleen cells compared to non-MMP-9-producing 5T33MMvt cells and homogenates/cells from non-tumour-bearing organs/mice, as measured by fluorescence release. This fluorescence release could be inhibited by the MMP-2/MMP-9-specific inhibitor, CTT. Activation of the prodrug in the 5T33MM spleen and BM homogenates was confirmed by chromatography. EV1-fluorescein isothiocyanate injection into 5T33MM-diseased animals resulted in a higher fluorescence release by the isolated BM and spleen cells compared to injection into healthy animals. In conclusion, MMP-9 activity can be used to activate prodrugs that target MM.

Animals↗
PubMed2005

Factors that influence special care nursery admissions to a district hospital in South-western Sydney.

OBJECTIVES: To explore the socio-demographic factors and maternal characteristics that influence special care nursery (SCN) admission for infants of more than 34 weeks' gestation. Particularly, this paper aims (i) to estimate the incidence of SCN admission by various mothers' socio-demographic factors; and (ii) to investigate the relationship between SCN admission and mothers' socio-demographic and obstetric and gynaecological factors. METHODS: This was a cohort study of 10,148 pregnant women who accessed the birthing unit within a public district hospital in south-western Sydney in New South Wales, between 1998 and 2001. The main outcome measure was risk factors for SCN admission. RESULTS: The incidence of SCN admission was 11.7%. Multivariate analysis revealed that the risk factors for SCN admission were diabetes, gestational diabetes, high parity, pregnancy induced hypertension, living in suburbs with low education and occupation index, and no private health insurance status. CONCLUSIONS: The results from this large population-based study suggest that, apart from clinical/medical factors, admission to a special care nursery at a District Hospital was significantly affected by maternal insurance status and level of education and occupation.

Adult↗
PubMed2004

Counting individual 41Ca atoms with a magneto-optical trap.

Atom trap trace analysis, a novel method based upon laser trapping and cooling, is used to count individual atoms of 41Ca present in biomedical samples with isotopic abundance levels between 10(-8) and 10(-10). The method is calibrated against resonance ionization mass spectrometry, demonstrating good agreement between the two methods. The present system has a counting efficiency of 2x10(-7). Within 1 h of observation time, its 3-sigma detection limit on the isotopic abundance of 41Ca reaches 4.5x10(-10).

Calcium Radioisotopes↗
PubMed2004

Enabling households to support successful migration of AIDS orphans in southern Africa.

Most southern African orphans are cared for by extended families but the implications of the spatial dispersal of such families are seldom recognized: orphans often have to migrate to new homes and communities. This paper, based on qualitative research conducted with children and guardians in urban and rural Lesotho and Malawi, examines orphans' migration experiences in order to assess how successful migration might best be supported. Most children found migration traumatic in the short term, but over time many settled into new environments. Although much AIDS policy in southern Africa stresses the role of communities, the burden of care lay with extended family households. Failed migrations, which resulted in renewed migration and trauma, were attributable to one of two household-level causes: orphans feeling ill-treated in their new families or changes in guardians' circumstances. Policy interventions to reduce disruption and trauma for young AIDS migrants should aim at facilitating sustainable arrangements by enabling suitable households to provide care. Reducing the economic costs of caring for children, particularly school-related costs, would: allow children to stay with those relatives (e.g. grandparents) best able to meet their non-material needs; reduce resentment of foster children in impoverished households; and diminish the need for multiple migrations.

Acquired Immunodeficiency Syndrome↗
PubMed2004

Bystander help within a polyepitope DNA vaccine improves immune responses to influenza antigens.

A polyepitope DNA vaccine has the potential to generate protective immune responses to a range of antigens in a single construct. We investigated whether it was possible to obtain responses to individual epitopes from different antigens, directly linked in a string, and whether the response to a given epitope was enhanced by adjacent epitopes within the construct. A polyepitope plasmid was created, which included three Th epitopes (influenza haemagglutinin, moth cytochrome c and ovalbumin), a Tc epitope (ovalbumin) and two B cell epitopes (haemagglutinin and ovalbumin). Mice were immunized with DNA by using a gene gun. Responses to the polyepitope DNA vaccine were compared with those to DNA vaccine comprising only the haemagglutinin Th and B epitopes (HAT(h)B) or with responses to the recombinant protein. These experiments showed that the polyepitope DNA vaccine induced greater antigen-specific responses to HAT(h)B peptide than the HAT(h)B DNA vaccine. Antigen-specific in vivo cytotoxic responses following polyepitope DNA vaccination were also clearly demonstrable. We conclude that a 'naked DNA' polyepitope vaccine generates specific responses to constituent epitopes and that adjacent irrelevant epitopes may enhance these responses.

Animals↗
PubMed2004

Audit of community-based anticoagulant monitoring in patients with thromboembolic disease: is frequent testing necessary?

Oral anticoagulant monitoring is managed by general practitioners in Auckland. An audit of this service in 452 patients demonstrated that anticoagulant control was in line with recommended international guidelines, with 58.3% of international normalized ratio (INR) measurements in the therapeutic range. However, the frequency of testing was high, with the majority of patients (68%), including those on long-term treatment, having INR measurements at weekly intervals. We question the need for such frequent INR testing.

Adolescent↗
PubMed2004

Production and health of pasture-fed dairy cattle following oral treatment with the ionophore lasalocid.

The aim of the study was to evaluate the effect of feeding the ionophore lasalocid on the productivity and health of seasonally calving, pasture-fed dairy cows. Dairy cows (n = 1020) from 4 herds were enrolled in a split-herd, prospective intervention study. Cows were blocked by breed and age, ranked on previous production, and then assigned to 2 treatment groups. Treatment cows were each exposed to 300 to 350 mg of lasalocid/d commencing 3 wk before and ending 18 wk after the start of the seasonal calving period. Milk production was determined on 3 occasions for each cow at approximately monthly intervals (herd tests 1 to 3), body condition score was determined fortnightly, and all disease occurrences were recorded. Lasalocid treatment increased milk volume milk protein and milk fat production by approximately 2%, without altering milk composition. Fewer lasalocid-treated cows than control cows (7.3 vs. 11.6%, respectively) were diagnosed with clinical mastitis. Lasalocid treatment of pasture-fed dairy cows resulted in reduced mastitis incidence and increased milk production without changes in body condition or negative effects on metabolic processes as monitored by metabolite concentrations.

3-Hydroxybutyric Acid↗
PubMed2003

Triple ionization of lithium by electron impact.

Ejection of the three electrons from lithium in a single electron collision has been observed for the first time. Triply charged lithium was observed in an ion time-of-flight spectrum following electron impact on a sample of ultracold, trapped lithium. The higher signal/background afforded by the trap environment made the observation of Li3+ possible. We measured the ratios of triple-to-double and double-to-single ionization at an impact energy of 1000 eV. The 3+/2+ ratio is approximately 0.001, a value 2 orders of magnitude lower than semiempirical predictions. We present a simple method that uses photoionization data combined with sum-rule analysis to predict the asymptotic charge-state ratios. The sum-rule predictions compare reasonably with experiment and shake calculations, but disagree sharply with the semiempirical estimates.

Journal Article↗
PubMed2003

Proapoptotic genes BAX and CD40L are predictors of survival in transitional cell carcinoma of the bladder.

The purpose of the study was to investigate the effects of expression of a range of genes involved in apoptosis on outcome in bladder cancer. Immunohistochemistry was used to examine expression of BCL2, BAX, P53, CD40 and CD40L in archival tissues of patients included in various treatment trials for transitional cell carcinoma (TCC) of the bladder. Data were collected on 94 patients who first presented with either invasive or superficial bladder cancer. Median follow-up for alive patients was 83 months (m) (range 12-195 m). Median survival was 80 m (95% CI=56-128 m). Median survivals for the various markers were as follows: BAX-positive patients 110 m vs BAX-negative patients 18 m (P=0.0002); CD40L-positive patients 95 m vs CD40L-negative patients 45 m (P=0.04); BCL2-positive patients 44 m and BCL2-negative patients 74 m, (P=0.64); CD40-positive patients 110 m and CD40 negative patients 45 m (P=0.12); and P53 positive patients 80 m and P53 negative patients 45 m (P=0.58). In conclusion, it was seen that overexpressions of BAX and CD40L are prognostic of better survival in TCC of the bladder. Our results also raise the possibility of the future development of CD40- and CD40 ligand-based immunotherapy for bladder cancer. This study links proapoptotic and antiapoptotic markers to overall survival.

Adult↗
PubMed2003

Risk factors for low birth weight in a socio-economically disadvantaged population: parity, marital status, ethnicity and cigarette smoking.

Low birth weight (LBW) is a public health problem, because it is associated with increased risk of morbidity and mortality. The principal aim of this study was to assess risk factors for LBW in a large multi-ethnic and socio-economically disadvantaged population. Data from 3242 mothers, who attended the Well Baby Clinic (Southwestern Sydney, Australia) for the first time, were analysed in relation to their demographic characteristics and socio-economic indices. The overall birthweight was 3377 +/- 577 g (mean +/- SD). In multiple linear regression analysis, smoking during pregnancy, marital status, parity, and country of birth were independently associated with birth weight. According to this analysis, lower birth weight was associated with mothers who had smoked during pregnancy (by 215.2 +/- 18.6 g), who were single (46.9 +/- 21 g), and of Asian background (108.5 +/- 38.2 g). However, higher parity was associated with significantly higher birth weight. The presence of each factor was coded as 1 and the absence, 0. A 'risk score' was then derived by summing up the individual scores. When birth weight was classified as 'low birth weight' (defined as those with birth weight being less than 2500 g) or normal birth weight, the overall prevalence of LBW was 1.9%. Each unit increase in the risk score was associated with a 1.9-fold (95% confidence interval: 1.5-2.6) increase in the risk of LBW. These data suggest that apart from marital status, ethnicity and parity, maternal smoking is the single most important preventable risk factors for LBW.

Female↗