Search PubMed⌕ Search

Biomedical subjects

J Pearson

Publications and source records attributed to J Pearson.

At least 19 recordsLinked to original sources
PubMed2002

Magnetization-orientation dependence of the superconducting transition temperature in the ferromagnet-superconductor-ferromagnet system: CuNi/Nb/CuNi.

The superconducting critical temperature (T(c)) of ferromagnet-superconductor-ferromagnet systems has been predicted to exhibit a dependence on the magnetization orientation of the ferromagnetic layers such that T(AP)(c)>T(P)(c) for parallel (P) and antiparallel (AP) configurations of the two ferromagnetic layers. We have grown CuNi/Nb/CuNi films via magnetron sputtering and confirmed the theoretical prediction by measuring the resistance of the system as a function of temperature and magnetic field. We find an approximately 25% resistance drop occurs near T(c) in Cu0.47Ni0.53(5 nm)/Nb(18)/CuNi(5) when the two CuNi layers change their magnetization directions from parallel to antiparallel, whereas there is no corresponding resistance change in the normal state.

Journal Article↗
PubMed2002

A systematic review of the use of atypical antipsychotics in autism.

Conventional antipsychotic medication is commonly prescribed to patients with autistic spectrum disorder. However, a high incidence of severe adverse reactions highlights the need to find more favourable treatments. Atypical antipsychotics may combine efficacy in ameliorating some autistic symptoms with a lower incidence of some adverse reactions. This article reviews the use of atypical antipsychotics in autistic disorder, with particular focus on behaviour, cognition and physical well-being. Thirteen studies using risperidone, three using olanzapine, one using clozapine, one using amisulpride and one using quetiapine were identified. Few firm conclusions can be drawn due to the limitations of the studies; however, there is an indication that risperidone may be effective in reducing hyperactivity, aggression and repetitive behaviours, often without inducing severe adverse reactions. Olanzapine and clozapine may also be effective; however, there is little evidence for using amisulpride or quetiapine in this population. Randomized trials are required to clarify the effectiveness of these agents.

Antipsychotic Agents↗
PubMed2001

Early-onset amyloid deposition and cognitive deficits in transgenic mice expressing a double mutant form of amyloid precursor protein 695.

We have created early-onset transgenic (Tg) models by exploiting the synergistic effects of familial Alzheimer's disease mutations on amyloid beta-peptide (Abeta) biogenesis. TgCRND8 mice encode a double mutant form of amyloid precursor protein 695 (KM670/671NL+V717F) under the control of the PrP gene promoter. Thioflavine S-positive Abeta amyloid deposits are present at 3 months, with dense-cored plaques and neuritic pathology evident from 5 months of age. TgCRND8 mice exhibit 3,200-4,600 pmol of Abeta42 per g brain at age 6 months, with an excess of Abeta42 over Abeta40. High level production of the pathogenic Abeta42 form of Abeta peptide was associated with an early impairment in TgCRND8 mice in acquisition and learning reversal in the reference memory version of the Morris water maze, present by 3 months of age. Notably, learning impairment in young mice was offset by immunization against Abeta42 (Janus, C., Pearson, J., McLaurin, J., Mathews, P. M., Jiang, Y., Schmidt, S. D., Chishti, M. A., Horne, P., Heslin, D., French, J., Mount, H. T. J., Nixon, R. A., Mercken, M., Bergeron, C., Fraser, P. E., St. George-Hyslop, P., and Westaway, D. (2000) Nature 408, 979-982). Amyloid deposition in TgCRND8 mice was enhanced by the expression of presenilin 1 transgenes including familial Alzheimer's disease mutations; for mice also expressing a M146L+L286V presenilin 1 transgene, amyloid deposits were apparent by 1 month of age. The Tg mice described here suggest a potential to investigate aspects of Alzheimer's disease pathogenesis, prophylaxis, and therapy within short time frames.

Aging↗
PubMed2001

Evaluation of 'Sun-safe': a health education resource for primary schools.

The aim of the study was to assess the effectiveness of 'Sun-safe', a computer-based resource designed to promote skin cancer awareness and educate children, aged 10-11 years, about the effects of excessive exposure to the sun and associated skin cancer preventive behaviours. Effectiveness was measured by changes in knowledge, attitudes and behavioural intentions using a self-completed questionnaire. A cluster, controlled evaluation design was used. Twelve schools were randomly allocated to the intervention arms of the study (workbook or computer), with a further four schools acting as controls (no intervention). One school allocated to the computer group had serious technical problems with their computers on the day of the intervention and had to be excluded from the study, leaving six schools in the workbook group and five in the computer group. One class in each of the 15 schools participated. The questionnaire was administered before the intervention, the day after and 6 weeks thereafter. The primary outcome measures were changes in mean scores at 6 weeks. In all, 376 children, 83% of the roll, completed both pre- and 6-week tests. Mixed-model analysis, allowing for pre-intervention score and the cluster effect, showed significant increases in knowledge scores in all three groups [workbook 2.36, 95% confidence interval (CI): 1.66 to 3.05; computer 1.73, 95% CI: 1.00 to 2.46; control 0.93, 95% CI: 0.11 to 1.74], but only the workbook group was significantly better than the control group (1.43, 95% CI: 0.36 to 2.50) and there was no significant difference between the intervention groups (0.63, 95% CI: -0.38 to 1.63). With regard to attitudes, both interventions showed significantly greater increases in scores than the control group, but there was no significant difference between them (workbook 2.37, 95% CI: 1.27 to 3.47; computer 1.92, 95% CI: 0.76 to 3.09; control -0.01, 95% CI: -1.28 to 1.27). Although the mean increases for behavioural intentions scores were small (workbook 0.66, 95% CI: 0.26 to 1.05; computer 1.11, 95% CI: 0.70 to 1.51; control 0.08, 95% CI: -0.37 to 0.52), those for the intervention groups were significantly better than the control group, but were not significantly different from each other. The evaluation showed significant improvements in knowledge, attitudes and behavioural intentions, which were still present 6 weeks after the intervention. This suggests that interventions employing the Sun-safe workbook and computer-based resources could be most usefully put into effect in the week before the start of the summer holidays.

Awareness↗
PubMed2001

Emergency transfer from independent hospitals to NHS hospitals: risk, reasons and cost.

BACKGROUND: In view of public concern about standards of emergency care in independent hospitals and the impact of transferred patients on NHS facilities we aimed to estimate the number and risk of emergency transfers from independent hospitals to NHS hospitals; to describe the circumstances; and estimate costs to the NHS. METHODS: Patients transferred in three months from 137 independent hospitals were identified from central records systems and local hospital enquiries. Circumstances were described by Directors of Nursing in telephone interviews. Numbers were weighted for whole year activity and non-participating hospitals to estimate total transfers in 1999. Medical Directors of NHS Trusts receiving the patients supplied durations of stay in critical care and other facilities. NHS Reference Costs were applied. RESULTS: There were 158 emergency transfers (plus 105 planned transfers, and 18 as a result of funding problems). Proportionately more emergency transfers were from hospitals lacking intensive care facilities. Patients over 65 years old constituted 61 per cent of transfers but only 25 per cent of all cases. Transfer followed major abdominal surgery in 42 (26 per cent) cases and major orthopaedic surgery in 31 (20 per cent), although these treatments constituted only 2 per cent and 3 per cent of the caseloads. There were an estimated 749 emergency transfers in 1999 (95 per cent confidence interval 640-875), a risk of 1 in 956 (all ages) and 1 in 392 (aged over 65); 729 had been funded privately, of whom two-thirds became NHS patients after transfer, costing Pound Sterling 2.61 million. CONCLUSIONS: The scale of emergency transfer (two per day) and resulting cost to the NHS is small. The risk is reducible if patients and interventions are matched to hospitals' critical care capabilities. Common clinical service guidelines should apply to NHS and independent hospitals.

Adolescent↗
PubMed2001

Analysis of Escherichia coli strains causing bacteriuria during pregnancy: selection for strains that do not express type 1 fimbriae.

Escherichia coli isolates from patients with bacteriuria of pregnancy were compared by PCR with isolates from patients with community-acquired cystitis for the presence of established virulence determinants. The strains from patients with bacteriuria of pregnancy were less likely to carry genes for P-family, S-family, and F1C adhesins, cytotoxic necrotizing factor 1, and aerobactin, but virtually all of the strains carried the genes for type 1 fimbriae. Standard mannose-sensitive agglutination of yeast cells showed that only 15 of 42 bacteriuria strains (36%) expressed type 1 fimbriae compared with 32 of 42 strains from community-acquired symptomatic infections (76%) (P < 0.01). This difference was confirmed by analysis of all isolates for an allele of the type 1 fimbrial regulatory region (fim switch), which negates type 1 fimbrial expression by preventing the fim switch from being inverted to the on phase. This allele, fimS49, was found in 8 of 47 bacteriuria strains from pregnant women (17.0%) compared with 2 of 60 strains isolated from patients with cystitis (3.3%) (P < 0.05). Determination of the phase switch orientation in vivo by analysis of freshly collected infected urine from patients with bacteriuria showed that the fim switch was detectable in the off orientation in 17 of 23 urine samples analyzed (74%). These data indicate that type 1 fimbriae are not necessary to maintain the majority of E. coli bacteriurias in pregnant women since there appears to be selection against their expression in this particular group. This is in contrast to the considered role of this adhesin in community-acquired symptomatic infections. The lack of type 1 fimbria expression is likely to contribute to the asymptomatic nature of bacteriuria in pregnant women, although approximately one-third of the bacteriuria isolates do possess key virulence determinants. If left untreated, this subset of isolates pose the greatest threat to the health of the mother and unborn child.

Alleles↗
PubMed2001

Attenuation of interleukin 8-induced nasal inflammation by an inhibitor peptide.

Polymorphonuclear neutrophils (PMNs) infiltrate tissue in response to chemoattractants, including interleukin 8 (IL-8). Infiltrating PMNs clear microorganisms but also cause tissue damage. We previously reported the presence in human bronchial lavage of a peptide that inhibits PMN functions. The current project assessed (1) effects of a synthetic analog of this peptide (synthetic neutrophil inhibitor peptide, SNIP) on IL-8-induced nasal inflammation in humans, (2) effects of SNIP on PMN apoptosis and chemotaxis, (3) specific binding of SNIP to PMNs, and (4) evidence of larger molecules with the SNIP sequence. Results show that SNIP attenuates IL-8-induced nasal inflammation, inhibits in vitro PMN chemotaxis to IL-8, and accentuates PMNs apoptosis. PMNs contain specific SNIP-binding sites and the integrin CR3 (CD11b/CD18), or a CR3-associated molecule, is one SNIP-binding molecule. Chemotaxis to IL-8 is most potently inhibited by SNIP in the presence of fibrinogen, a CR3 ligand. Antiserum against the SNIP sequence recognizes a 70-kDa protein in bronchoalveolar lavage and an anti-SNIP immunoaffinity column binds a 70-kDa protein in U937 cell culture supernatant. U937 cell mRNA contains a 1.8-kb transcript detected with degenerate oligonucleotides designed from the SNIP sequence. These studies demonstrate that a synthetic inhibitor peptide can attenuate in vivo nasal inflammation through downregulatory effects on PMNs.

Analysis of Variance↗
PubMed2001

Longitudinal effects of aging on serum total and free testosterone levels in healthy men. Baltimore Longitudinal Study of Aging.

Many studies have shown cross-sectional (and two small studies, longitudinal) declines in total and/or free testosterone (T) levels, with age, in men. The extent to which decline in T is the result of the aging process per se, as opposed to chronic illness, medication use, and other age-related factors, remains controversial. The frequency with which aging leads to T levels consistent with hypogonadism has also not been defined. These issues bear on the potential use of T replacement in aging men, because aging and hypogonadism have, in common, reduced bone and lean body mass and muscle strength and increased total and abdominal fat. We measured T and sex hormone-binding globulin (SHBG), by RIA, in stored samples from 890 men in the Baltimore Longitudinal Study on Aging. Using a mixed-effects model, we found independent effects of age and date of sampling to reduce T levels. After compensating for date effects, which investigation suggested was artifactual, we observed significant, independent, age-invariant, longitudinal effects of age on both T and free T index (free T index = T/SHBG), with an average change of -0.124 nmol/L.yr and -0.0049 nmol T/nmol SHBG.yr. T, but not free T index, also decreased with increasing body mass index. Use of beta-blocking drugs was associated with higher T and higher free T index levels. Using total T criteria, incidence of hypogonadal T levels increased to about 20% of men over 60, 30% over 70 and 50% over 80 yr of age, and even greater percentages when free T index criteria were employed. Our observations of health factor independent, age-related longitudinal decreases in T and free T, resulting in a high frequency of hypogonadal values, suggest that further investigation of T replacement in aged men, perhaps targeted to those with the lowest serum T concentrations, are justified.

Adult↗
PubMed2001

Evaluation of a program to promote positive parenting in the neonatal intensive care unit.

PURPOSE: To describe and evaluate a parent education program to promote positive parenting in the NICU. DESIGN: Program evaluations completed by parent participants and staff members. SAMPLE: 104 parents (59 mothers and 45 fathers) who attended the Parent's Circle; also 44 NICU or SCN staff members. MAIN OUTEOME VARIABLE: Family and staff evaluations of the Parent's Circle program. RESULTS: Families reported that attending Parent's Circle helped them gain perspective on their situation, feel supported, learn key developmental concepts, locate hospital and community resources, and optimize interactions with their fragile infant. Staff reported that the knowledge parents gained from Parent's Circle influenced their interactions and behaviors in the NICU.

Adaptation, Psychological↗
PubMed2001

Cervical teratoma in a dog.

A young adult boxer dog was examined for a painless swelling in the left cranial cervical area that was refractory to antibiotic therapy. Ultrasound examination revealed a hypoechoic mass abutting the rostrolateral aspect of the left mandibular salivary gland. The cystic mass was excised and was found to extend through the capsule of the salivary gland and appeared to be confluent with the glandular tissue at this point. Histopathological examination of the excised tissue demonstrated tissue from all 3 germinal layers. There was no indication of malignancy and the mass was diagnosed as a benign cervical teratoma. Hypotheses regarding the origin of teratomas in general are discussed and the origin of the teratoma in this case is suggested.

Animals↗
PubMed2000

Monitoring osteoporosis therapy with bone densitometry: misleading changes and regression to the mean. Fracture Intervention Trial Research Group.

CONTEXT: The principle of "regression to the mean" predicts that patients with unusual responses to treatment might represent outliers who are likely to have more typical responses if treatment is continued without change. OBJECTIVE: To test whether women who lose bone mineral density (BMD) during the first year of treatment for osteoporosis continue to lose BMD if the same treatment is continued beyond 1 year. DESIGN AND SETTING: Two randomized, double-blind, placebo-controlled trials in 11 US clinical research centers for the Fracture Intervention Trial and 180 centers in the United States and other countries for the Multiple Outcomes of Raloxifene Evaluation Trial. PARTICIPANTS AND INTERVENTIONS: Postmenopausal women with low BMD assigned to treatment with 5 mg/d of alendronate sodium in the Fracture intervention Trial who completed 2 years of BMD monitoring and adhered to study medication (n = 2634), and postmenopausal women with osteoporosis assigned to treatment with 60 or 120 mg/d of raloxifene hydrochloride in the Multiple Outcomes of Raloxifene Evaluation trial who similarly completed 2 years of monitoring while adhering to study medication (n = 3954). MAIN OUTCOME MEASURES: Baseline, 12-, and 24-month hip and spine BMD. RESULTS: Women with the greatest loss of BMD during the first year of treatment were the most likely to gain BMD during continued treatment. Specifically, among women taking alendronate whose hip BMD decreased by more than 4% during the first year, 83% (95% confidence interval [CI], 82%-84%)had increases in hip BMD during the second year, with an overall mean increase of 4.7%. In contrast, those who seemed to gain at least 8% during the first year lost an average of 1% (95% CI, 0.1%-1.9%) during the next year. Similar results were observed among women taking raloxifene for 2 years. CONCLUSIONS: Our data suggest that most women who lose BMD during the first year of treatment with alendronate or raloxifene will gain BMD if the same treatment is continued for a second year. These results illustrate the principle of regression to the mean and suggest that effective treatments for osteoporosis should not be changed because of loss of BMD during the first year of use.

Absorptiometry, Photon↗
PubMed2000

The social context of insight in schizophrenia.

BACKGROUND: Psychiatrists place great weight on impaired insight in schizophrenia, generally attributing it to pathological mental processes. However, denial of illness may be based on attitudes common in patients' social and cultural groups. Moreover, even where denial of illness has a pathological element, it may be affected by the social context. In this paper, we predicted that denial of illness would be associated with social distance between clinician and patient, and reduced by access to 'normalizing' social interaction. METHOD: One hundred and fifty patients with schizophrenia in the London arm of the European Schizophrenia cohort were assessed using the 'Awareness of Illness' (AI) subscale of David's Assessment of Insight. Clinical and social attributes were related to AI. RESULTS: There was little evidence for our social distance hypotheses: there was little variation in AI by social class, ethnicity, membership of a drug taking culture or the presence of strongly held religious beliefs. However, there were strong relations between AI and the size of primary group, consistent with our normalizing hypothesis. CONCLUSIONS: The normalizing function of social support is in line with modern psychological models of delusion formation. Longitudinal data will eventually be available from the current study that will assist in establishing the causal direction of this association.

Adult↗
PubMed2000

Susceptibility testing: accurate and reproducible minimum inhibitory concentration (MIC) and non-inhibitory concentration (NIC) values.

Measuring the minimum inhibitory concentration (MIC) of a substance by current methods is straightforward, whereas obtaining useful comparative information from the tests can be more difficult. A simple technique and a method of data analysis are reported which give the experimentalist more useful information from susceptibility testing. This method makes use of a 100-well microtitre plate and the analysis uses all the growth information, obtained by turbidometry, from each and every well of the microtitre plate. A modified Gompertz function is used to fit the data, from which a more exact value can be obtained for the MIC. The technique also showed that at certain concentrations of inhibitor, there was no effect on growth relative to a control well (zero inhibitor). Above a threshold value, which has been termed the non-inhibitory concentration or NIC, growth becomes limiting until it reaches the MIC, where no growth relative to the control is observed.

Anti-Bacterial Agents↗