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Biomedical subjects

T Jackson

Publications and source records attributed to T Jackson.

At least 19 recordsLinked to original sources
PubMed2000

Evaluation of skin sensitization potential of jet fuels by murine local lymph node assay.

Jet A and JP-8 are the major jet fuels used in civilian and military (US Air Force) flights, respectively. JP-8+100 is a new jet fuel recently introduced by the US Air Force. Besides lung exposure, skin is the potential route of exposure to jet fuels. The purpose of the present study was to investigate the skin sensitization potential of jet fuels (Jet A, JP-8 and JP-8+100) using murine Local lymph node assay (LLNA). Female CBA/Ca mice (8-12-weeks-old) were used in the study. Dinitrochlorobenzene (DNCB, 0.25% w/v) and paraaminobenzoic acid (PABA, 2.5% w/v) were used as positive and negative control, respectively and acetone: olive oil (4:1, AOO) was used as the vehicle (control). All three jet fuels caused a proliferative activity significantly greater than the control (P<0.01). Our results demonstrate that JP-8 is a weak skin sensitizer [stimulation index (SI)=3.17]. The SI of Jet A and JP-8+100 were 2.44 and 2.38, respectively, hence are not considered as skin sensitizers. Interestingly, the SI of JP-8 with butylated hydroxytoluene (BHT) was consistently lower than JP-8, though the difference was not statistically significant (P>0.05). BHT, which is an antioxidant additive of JP-8+100, reduced the skin sensitization potential of JP-8. Furthermore, the lower SI of JP-8+100 could be partially attributed to the presence of BHT. The findings reported here suggest that care should be taken to minimize dermal exposure to jet fuels especially JP-8 to avoid skin sensitization.

Animals↗
PubMed2000

Novel roles for elongin C in yeast.

Mammalian Elongin C is a 112-amino acid protein that binds to the von Hippel-Lindau (VHL) tumor suppressor and to Elongin A, the transcriptionally active subunit of the RNA polymerase II elongation factor, SIII. It is conserved in eukaryotic cells, as homologs have been identified in Saccharomyces cerevisiae, Drosophila melanogaster and Caenorhabditis elegans. The mammalian protein is thought to function as part of a ubiquitin targeting E3 ligase, yet the function in yeast has not been determined. In this report we examine the role of Elongin C in yeast and establish that yeast Elongin C may function in a mode distinct from its role as an E3 ligase. The RNA is expressed ubiquitously, albeit at low levels. Two hybrid analyses demonstrate that Elongin C in yeast interacts with a specific set of proteins that are involved in the stress response. This suggests a novel role for Elongin C and provides insights into additional potential functions in mammalian cells.

AMP-Activated Protein Kinases↗
PubMed2000

Personality differences between eating-disordered women and a nonclinical comparison sample: a discriminant classification analysis.

The present study evaluated the extent to which eating-disordered and nonclinical comparison samples could be differentiated on self-reported personality measures of autonomy and sociotropy and a projective measure of dependency. Sixty-two women meeting diagnostic criteria for eating disorder and a nonpsychiatric comparison group of 62 women completed the autonomy and sociotropy subscales of the Personal Style Inventory-II and the Rorschach Oral Dependency Scale (ROD). A discriminant classification analysis indicated 85.5% of eating-disordered subjects and 88.7% of control subjects were identified accurately from their scores on autonomy, sociotropy. and ROD. Results suggest that the experience of eating disorders is associated with a mixed clinical presentation characterized by issues related to sociotropy-dependency, and especially, achievement-related vulnerabilities. Potentially fruitful areas for future study include assessing the utility of autonomy and sociotropy as predictors of eating disturbances in prospective research and evaluating their utility in predicting treatment prognosis among patients with eating disorders.

Adolescent↗
PubMed2000

In vitro and in vivo characterization of biodegradable enoxacin microspheres.

The in vitro release and plasma concentration profiles of sustained release enoxacin microspheres intended for the treatment of bone and systemic infections due to sensitive strains of bacteria were investigated. Microspheres of enoxacin were prepared by using poly(glycolic acid-co-DL-lactic acid) (PLGA) by the emulsion solvent evaporation technique and characterized by in vitro release in an incubator, and in vivo release in the rat subcutaneous model. The microspheres were spherical in nature, and particle size range had a significant influence on the in vitro release. The enoxacin plasma concentration 2 h after the administration of treatments was two-fold higher in animals who received the free drug compared with those who received microspheres of size range 125-250 microm. The plasma of animals who received the free drug was depleted of enoxacin by the end of the first day. However, the plasma concentration of enoxacin in the animals who received microspheres was sustained above 0.5 microg/ml for about 8 days. The results show that biodegradable microspheres of enoxacin can be prepared which release the antibiotic in vivo for days following a subcutaneous administration. This should provide a means for the sustained treatment of infections due to sensitive strains of bacteria.

Animals↗
PubMed2000

A methodology designed to increase accuracy and safety in stereotactic brain surgery.

A series of technical tips and devices designed to increase accuracy and safety in stereotactic surgery are presented. We use stereotactic magnetic resonance imaging with three-dimensional magnetization-prepared rapid gradient-echo (MP-RAGE) imaging to minimize image distortion, and a three-dimensional stereotactic planning system for accurately registering three-dimensional space. We also developed several technical devices useful for stereotactic intracranial procedures; an applicator system attached to the frame which simulates the fiducial markers in order to keep the target at a suitable position in stereotactic space; a torque wrench to set the torque on the fixing pins to the frame reproducibly at 5 inch pounds in order to keep distortion of the frame to a minimum while maintaining secure fixation; an entry point marker to maintain the calculated trajectory angle; a straightening cannula to prevent the thermo-coagulation needle from bending; a microvascular Doppler and its holder to detect significant vessels and to know their precise depth in order to avoid vascular injury from thermocoagulation; a burr hole button device to secure depth electrode cables at the patient's skull.

Brain↗
PubMed2000

Foot-and-mouth disease virus is a ligand for the high-affinity binding conformation of integrin alpha5beta1: influence of the leucine residue within the RGDL motif on selectivity of integrin binding.

Field isolates of foot-and-mouth disease virus (FMDV) use RGD-dependent integrins as receptors for internalization, whereas strains that are adapted for growth in cultured cell lines appear to be able to use alternative receptors like heparan sulphate proteoglycans (HSPG). The ligand-binding potential of integrins is regulated by changes in the conformation of their ectodomains and the ligand-binding state would be expected to be an important determinant of tropism for viruses that use integrins as cellular receptors. Currently, alphavbeta3 is the only integrin that has been shown to act as a receptor for FMDV. In this study, a solid-phase receptor-binding assay has been used to characterize the binding of FMDV to purified preparations of the human integrin alpha5beta1, in the absence of HSPG and other RGD-binding integrins. In this assay, binding of FMDV resembled authentic ligand binding to alpha5beta1 in its dependence on divalent cations and specific inhibition by RGD peptides. Most importantly, binding was found to be critically dependent on the conformation of the integrin, as virus bound only after induction of the high-affinity ligand-binding state. In addition, the identity of the amino acid residue immediately following the RGD motif is shown to influence differentially the ability of FMDV to bind integrins alpha5beta1 and alphavbeta3 and evidence is provided that alpha5beta1 might be an important FMDV receptor in vivo.

Amino Acid Motifs↗
PubMed2000

The epithelial integrin alphavbeta6 is a receptor for foot-and-mouth disease virus.

Field isolates of foot-and-mouth disease virus (FMDV) have been shown to use the RGD-dependent integrin alphavbeta3 as a cellular receptor on cultured cells. However, several other RGD-dependent integrins may have the potential to act as receptors for FMDV in vivo. Of these, alphavbeta6 is a likely candidate for use as a receptor by FMDV as it is expressed on epithelial cells, which correlates with the tissue tropism of the virus. In this report, we show that human colon carcinoma cells (SW480) that are normally nonpermissive for FMDV become susceptible to infection as a result of transfection with the integrin beta6 subunit and expression of alphavbeta6 at the cell surface. Integrin alphavbeta6 is the major site for virus attachment on the beta6-transfected cells, and binding to alphavbeta6 serves to increase the rate of virus entry into these cells. In addition, we show that virus binding and infection of the beta6-transfected cells is mediated through an RGD-dependent interaction that is specifically inhibited by a monoclonal antibody (10D5) that recognizes alphavbeta6. These studies establish a role for alphavbeta6 as a cellular receptor for FMDV.

Animals↗
PubMed2000

Culture and self-presentation as predictors of shyness among Japanese and American female college students.

Self-presentation theories of shyness have been supported in North American samples but have not been evaluated cross-culturally. This study examined the relative influence of cultural and psychological variables on self-reported shyness among Japanese and American college students. 35 female Japanese-born and 47 United States-born Euro-American female students completed the Shyness Scale, Rosenberg Self-esteem Scale, Interpersonal Competence Questionnaire, Sensitivity to Rejection Scale, and Individualism-Collectivism Scale, and a demographic data sheet. After statistically controlling for Individualism-Collectivism, psychological measures, especially perceived interpersonal competence and sensitivity to rejection, combined for Adjusted R2 = .32 in shyness. Findings suggest that similar factors are central to experiences of shyness for both samples. Researchers should assess the stability of such findings in larger, heterogeneous samples and evaluate whether treatment strategies that reduce expectations of rejection and increase perceived interpersonal competence have comparable efficacy in reducing shyness across cultures.

Cross-Cultural Comparison↗
PubMed1999

Did Wellington have too many acute psychiatric beds in 1996?

AIMS: (1) To establish whether, as believed by local clinicians, there is a shortage of acute psychiatric beds available in Wellington. (2) To compare the current situation with that of seven years ago, before the beginning of the reduction in bed numbers, as a part of deinstitutionalisation and care in the community. (3) To study the effect on occupancy of changing availability. METHOD: Data were obtained retrospectively for the calendar years 1996 and 1989. These were examined using an analysis of variance and the results of the two years were compared. RESULTS: There were 214 days in 1996 when there were no acute psychiatric beds available. The mean daily occupancy was 100%. Comparing like populations, there was a highly significant increase in the mean occupancy as the availability decreased from 1989 to 1996. Conversely, there was a decrease in occupancy as availability temporarily increased during 1996. CONCLUSION: The number of acute psychiatric beds available in Wellington in 1996 was insufficient to meet the needs of the population, given the alternative resources available at that time. This is of particular concern in light of proposals to reduce the number of beds further.

Analysis of Variance↗
PubMed1999

The structure and function of a foot-and-mouth disease virus-oligosaccharide receptor complex.

Heparan sulfate has an important role in cell entry by foot-and-mouth disease virus (FMDV). We find that subtype O1 FMDV binds this glycosaminoglycan with a high affinity by immobilizing a specific highly abundant motif of sulfated sugars. The binding site is a shallow depression on the virion surface, located at the junction of the three major capsid proteins, VP1, VP2 and VP3. Two pre-formed sulfate-binding sites control receptor specificity. Residue 56 of VP3, an arginine in this virus, is critical to this recognition, forming a key component of both sites. This residue is a histidine in field isolates of the virus, switching to an arginine in adaptation to tissue culture, forming the high affinity heparan sulfate-binding site. We postulate that this site is a conserved feature of FMDVs, such that in the infected animal there is a biological advantage to low affinity, or more selective, interactions with glycosaminoglycan receptors.

Adaptation, Physiological↗
PubMed1999

Differences in psychosocial experiences of employed, unemployed, and student samples of young adults.

The author conducted this cross-sectional study to assess the extent to which employed, unemployed, and student samples of young adults could be differentiated on the basis of psychosocial experiences. Forty-four employed, 41 unemployed, and 42 student volunteers completed measures of emotional distress, time structure, financial strain, skill use, task variety, social support, and demographic information. After the effects of educational and income differences were statistically controlled, results indicated that unemployed participants reported poorer functioning than employed and student respondents on most measures. In a discriminant function analysis, 66% of the sample was correctly identified from scores on psychosocial measures, with higher classification rates for employed and unemployed participants. The findings provide additional support for contextual models of mental health and suggest that full-time education partially buffers the negative psychological consequences of unemployment when opportunities for employment are absent.

Adaptation, Psychological↗
PubMed1999

Cost effectiveness of rotavirus vaccination in Australia.

OBJECTIVE: Rotavirus gastroenteritis causes substantial morbidity, including hospital admission, in young children. In the context of recent vaccine developments, this study aimed to estimate the cost-effectiveness of a rotavirus vaccination program in Australia. METHOD: Standard methods of health economic evaluation were used to assess the total cost of rotavirus immunisation (as the difference between estimated vaccination program costs and the cost of disease that would be avoided by immunisation) and relate this to the number of cases of disease that would be prevented. Estimates were made from both societal and health care systems perspectives. RESULTS: Based on Australian data on disease incidence and cost of hospitalisation, the current annual cost of rotavirus disease is about $26.0 million. Using conservative vaccine efficacy estimates, current immunization uptake rates and a cost of $30 per dose of vaccine, rotavirus immunisation would incur a net societal cost of $2.9 million ($11 per child), at a gross program cost of $21.6 million. These estimates are sensitive to two sources of uncertainty in the estimation of program delivery costs: vaccine price and whether separate immunization visits would be required. CONCLUSION: A rotavirus immunisation program would be cost-neutral to Australian society at a vaccine price of $26 per dose (or $19 when health care system costs only are considered). IMPLICATIONS: Rotavirus immunization may be cost-effective in Australia, but considerable uncertainty remains. Policy decisions will depend heavily on pricing of the vaccine and may also need to consider intangible costs not accounted for in this analysis.

Child, Preschool↗
PubMed1999

Influence of the teacher-student relationship on childhood conduct problems: a prospective study.

Examined the influence of the quality of the teacher-student relationship on children's subsequent levels of aggression in a sample of 61 second and third-grade children nominated and rated by their teachers as aggressive. The stability of teachers' and children's reports of relationships quality across academic years was in the low to moderate range. Teachers and children showed little agreement in their reports of relationship quality. Teachers' and children's reports of relationship quality in year 1 (Y1) predicted teacher-rated aggression the following year, controlling for Y1 ratings of aggression. Teachers' reports of relationship quality across Y1 and Y2 predicted peer-rated aggression, but not teacher-rated aggression, in Y3, controlling for Y1 aggression. Consistent with a buffering role for teacher-student relationships, a positive teacher-student relationship was of greatest benefit to children whose mothers reported rejecting parenting histories. We discuss implications for school-based prevention programs.

Aggression↗
PubMed1999

Two brothers with varying combinations of severe developmental delay, epilepsy, microcephaly, tetralogy of Fallot and hydronephrosis.

We report on a sib pair who manifest a pattern of anomalies which appears to be unique and for which we are unable to provide a cytogenetic or molecular genetic explanation. While a number of their physical features are distinct, their overall appearance and pattern of neurological impairment suggest they suffer from the same genetic disorder.

Abnormalities, Multiple↗
PubMed1998

Transport vesicles: coats of many colours.

Clathrin-coated vesicles transport proteins and membranes between intracellular compartments. Adaptor molecules determine vesicle specificity; recently, a third type of adaptor protein, AP3, has been identified and implicated in the biogenesis of endosomal and lysosome-related organelles.

Adaptor Protein Complex 3↗
PubMed1998

Atmosphere-surface interactions on Mars: delta 17O measurements of carbonate from ALH 84001.

Oxygen isotope measurements of carbonate from martian meteorite ALH 84001 (delta18O = 18.3 +/- 0.4 per mil, delta17O = 10.3 +/- 0.2 per mil, and Delta17O = 0.8 +/- 0.05 per mil) are fractionated with respect to those of silicate minerals. These measurements support the existence of two oxygen isotope reservoirs (the atmosphere and the silicate planet) on Mars at the time of carbonate growth. The cause of the atmospheric oxygen isotope anomaly may be exchange between CO2 and O(1D) produced by the photodecomposition of ozone. Atmospheric oxygen isotope compositions may be transferred to carbonate minerals by CO2-H2O exchange and mineral growth. A sink of 17O-depleted oxygen, as required by mass balance, may exist in the planetary regolith.

Atmosphere↗
PubMed1998

Relations of employment status to emotional distress among chronic pain patients: a path analysis.

OBJECTIVE: This cross-sectional study evaluated the extent to which relations between employment status and emotional distress are mediated by pain-related and psychosocial measures among employed and unemployed persons with chronic pain. DESIGN: A total of 40 unemployed and 43 employed persons reporting chronic pain were recruited from pain services at a tertiary-care hospital and community-based organizations. Volunteers completed self-report measures of pain severity, subjective financial stress, time structure, emotional distress, and background data. RESULTS: A path analysis indicated that pain severity had direct associations with both emotional distress and employment status. In addition, employment status was only indirectly related to emotional distress; this relation was mediated by levels of reported financial strain and structured purposeful time use. CONCLUSIONS: Findings suggest that pain severity and the quality of specific experiences related to being employed or unemployed as opposed to employment status per se correspond directly to levels of emotional distress reported by some persons with chronic pain.

Adult↗