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Biomedical subjects

P Lewis

Publications and source records attributed to P Lewis.

At least 19 recordsLinked to original sources
PubMed1999

Incorporation of esterified soybean isoflavones with antioxidant activity into low density lipoprotein.

We have recently reported that dietary intake of soybean isoflavone phytoestrogens resulted in increased oxidation resistance of isolated low density lipoprotein (LDL). In order to explore the underlying mechanisms we designed two types of in vitro experiments. First, we prepared several different isoflavone fatty acid esters to increase their lipid solubility and studied their incorporation into LDL. Second, the oxidation resistance of the isoflavone-containing LDLs was investigated with Esterbauer's 'conjugated diene' method using Cu2+ as prooxidant. Unesterified daidzein and genistein as well as genistein stearic acid esters were incorporated into LDL to a relatively small extent (0.33 molecules per LDL particle, or less) and they did not significantly influence oxidation resistance. The oleic acid esters of isoflavones were incorporated more effectively, reaching a level of 2.19 molecules per LDL particle or more, and the 4',7-O-dioleates of daidzein and genistein exhibited prolongations of lag times by 46% (P<0.05) and 202% (P<0.01), respectively. A smaller but significant increase in lag time (20.5%, P<0.01) was caused by daidzein 7-mono-oleate. In summary, esterification of soybean isoflavones daidzein and genistein with fatty acids at different hydroxyl groups provided lipophilicity needed for incorporation into LDL. Some isoflavone oleic acid esters increased oxidation resistance of LDL following their incorporation.

Antioxidants↗
PubMed1999

Studies of human immunodeficiency virus type 1 mucosal viral shedding and transmission in Kenya.

If human immunodeficiency virus type 1 (HIV-1) vaccines are to be highly effective, it is essential to understand the virologic factors that contribute to HIV-1 transmission. It is likely that transmission is determined, in part, by the genotype or phenotype (or both) of infectious virus present in the index case, which in turn will influence the quantity of virus that may be exchanged during sexual contact. Transmission may also depend on the fitness of the virus for replication in the exposed individual, which may be influenced by whether a virus encounters a target cell that is susceptible to infection by that specific variant. Of interest, our data suggest that the complexity of the virus that is transmitted may be different in female and male sexual exposures.

Adult↗
PubMed1999

Subtypes of human immunodeficiency virus type 1 and disease stage among women in Nairobi, Kenya.

In sub-Saharan Africa, where the effects of human immunodeficiency virus type 1 (HIV-1) have been most devastating, there are multiple subtypes of this virus. The distribution of different subtypes within African populations is generally not linked to particular risk behaviors. Thus, Africa is an ideal setting in which to examine the diversity and mixing of viruses from different subtypes on a population basis. In this setting, it is also possible to address whether infection with a particular subtype is associated with differences in disease stage. To address these questions, we analyzed the HIV-1 subtype, plasma viral loads, and CD4 lymphocyte levels in 320 women from Nairobi, Kenya. Subtype was determined by a combination of heteroduplex mobility assays and sequence analyses of envelope genes, using geographically diverse subtype reference sequences as well as envelope sequences of known subtype from Kenya. The distribution of subtypes in this population was as follows: subtype A, 225 (70.3%); subtype D, 65 (20.5%); subtype C, 22 (6.9%); and subtype G, 1 (0.3%). Intersubtype recombinant envelope genes were detected in 2.2% of the sequences analyzed. Given that the sequences analyzed represented only a small fraction of the proviral genome, this suggests that intersubtype recombinant viral genomes may be very common in Kenya and in other parts of Africa where there are multiple subtypes. The plasma viral RNA levels were highest in women infected with subtype C virus, and women infected with subtype C virus had significantly lower CD4 lymphocyte levels than women infected with the other subtypes. Together, these data suggest that women in Kenya who are infected with subtype C viruses are at more advanced stages of immunosuppression than women infected with subtype A or D. There are at least two models to explain the data from this cross-sectional study; one is that infection with subtype C is associated with a more rapid disease progression, and the second is that subtype C represents an older epidemic in Kenya. Discriminating between these possibilities in a longitudinal study will be important for increasing our understanding of the role of specific subtypes in the transmission and pathogenesis of HIV-1.

Base Sequence↗
PubMed1999

An analysis of the communication tactics used by hearing-impaired adults.

The aim of this study was to establish whether and to what degree certain types of communication strategies (hearing tactics) used by hearing-impaired adults could be shown to co-occur, and to find out which strategies were more likely to be used in which type of communicative situations. A consecutive series of 100 patients attending an audiological rehabilitation clinic was given a questionnaire asking how often they used each of five different hearing tactics in 11 different situations. 'Avoidance' and 'request for repetition' were the tactics used most commonly. 'Pretending to hear/understand' and 'positioning self to improve hearing' were used less frequently, with 'interruption' the least commonly used. There was some association between tactics and situations but no clear picture emerged. In a reassessment of our methodology and results, we suggest that the future research of communication strategies would benefit from a sociolinguistic approach based on the qualitative analysis of naturally occurring discourse (conversation) of hard-of-hearing people, focusing on the use of different strategies in relation to communicators' goals in interaction.

Adolescent↗
PubMed1999

Job satisfaction in a rural differentiated-practice setting.

This article reports the findings of a 3-year study that assessed the job satisfaction of nursing personnel in a rural nursing center that uses a differentiated practice model. Job satisfaction was measured using the Brayfield Job Satisfaction Questionnaire, the McCloskey/Mueller Satisfaction Survey, and the Job Descriptive Index. A high level of job satisfaction was found across all 3 years. Factors associated with job satisfaction are also described. The findings of this study add to the growing body of literature on the importance of differentiated practice in creating satisfying work environments.

Community Health Nursing↗
PubMed1998

Improved freedom from PSA failure with whole pelvic irradiation for high-risk prostate cancer.

PURPOSE: To determine the impact of whole pelvic irradiation on the risk of PSA failure in prostate cancer patients, at high predicted risk for lymph node involvement, receiving definitive radiotherapy. MATERIALS AND METHODS: Between October 1987 and December 1995, 506 patients with clinically localized prostate cancer were treated with definitive radiotherapy at UCSF and affiliated institutions. Treatment consisted of 4-field whole pelvic irradiation followed by a prostate-only boost, or prostate-only treatment (median follow-up was 35 months and 30 months, respectively). PSA failure was defined as: 1. a PSA value > or = 1 ng/ml; or 2. a PSA value that rose > or = 0.5 ng/ml in < or = 1 year posttreatment on two consecutive measurements, with the first rise defined as the time of failure. The calculated risk of lymph node positivity (%rLN+) was defined as 2/3(iPSA) + 10(GS-6), and high risk was defined as %rLN+ > or = 15%. Univariate and multivariate analyses were performed. RESULTS: A total of 201 high-risk patients were identified. High-risk patients who received whole pelvic irradiation had significantly improved freedom from PSA failure compared to those who received prostate-only treatment (median PFS = 34.3 months vs. 21.0 months; p = 0.0001). Potential confounding variables, including initial PSA, Gleason score, T stage, radiation dose, year of treatment, use of three-dimensional (3D) conformal techniques, and use of hormone therapy, did not account for the observed difference in time to PSA failure. Multivariate analysis revealed type of radiation treatment to be the most significant independent predictor of outcome. CONCLUSION: Whole pelvic radiotherapy significantly improves the PSA failure-free survival in patients with a high calculated risk of lymph node positivity.

Analysis of Variance↗
PubMed1998

Ticlopidine-induced neutropenia mimicking sepsis early after intracoronary stent placement.

We report a case of ticlopidine-induced profound neutropenia early in the course of therapy, which was manifest as a febrile systemic illness mimicking sepsis. This clinical presentation was potentially indicative of a contaminated intracoronary stent. The patient's signs and symptoms of illness promptly resolved with removal of ticlopidine, and no infection was documented. Review of indications for ticlopidine use, potential adverse effects, and monitoring recommendations are discussed.

Coronary Angiography↗
PubMed1998

Living with a person who has Parkinson's disease: the spouse's perspective by stage of disease. Parkinson's Study Group.

The objective of this study was to examine the experience of spouses caregiving for their spouse with Parkinson's disease (PD) and to determine whether their experiences differed by stage of disease. By using a cross-sectional design and mail questionnaire data from 380 spouse caregivers across 23 sites of the Parkinson Study Group, key caregiver variables were examined by stage of PD. Three categories of variables--caregiver role strain (10 measures), caregiver situation (four measures), and caregiver characteristics (four measures)--were analyzed by using t tests with Bonferroni correction. Specific types and amounts of role strain accumulated as the disease progressed, and they differed significantly between stages (p < 0.05). In the caregiving situation, the mean number of caregiving tasks tripled by stage 4/5. Negative changes in lifestyle plus decreases in predictability in caregivers' lives increased significantly in late-stage disease (p < 0.05). Caregiver characteristics of physical health and preparedness did not significantly differ across stages of disease. Depression was significantly higher by stage 4/5. Mutuality, the positive quality of the relationship as perceived by the caregiving spouse, declined beginning at stage 2. Caregiver strain is experienced across all stages of PD and accumulates significantly as the disease progresses. This study defines types and amounts of strain by stage of disease, which will be helpful in designing formal intervention trials to provide more effective help for spouse caregivers.

Aged↗
PubMed1998

Rabies virus entry into endosomes in IMR-32 human neuroblastoma cells.

Early events in rabies virus entry into cultured IMR-32 human neuroblastoma cells were investigated. After adsorption of rabies virus to the cell surface in the cold and warming to 37 degrees C in the presence of tracers for early endosomes, rabies virus and tracers were localized by immunofluorescence microscopy. After 5 min, rabies virus colocalized with Lucifer Yellow, Texas Red-dextran, rhodamine-wheat germ agglutinin, and transferrin receptor in puncta in the cell body, neurites, and nerve terminals. Rabies virus did not colocalize with lysosomal glycoprotein. An acidotropic probe revealed that some of the virus-containing puncta were acidified. Rabies virus also colocalized with synapsin I, a synaptic vesicle marker, in swellings along processes, indicating some virus enters nerve terminals. Electron microscopy revealed the presence of rabies virus within irregular membrane compartments located near the cell surface in the cell body and neurites. The membrane of the virus particle was often continuous with that of the vacuole. It is concluded that rabies virus enters IMR-32 neuroblastoma cells by adsorptive endocytosis and that, shortly after entry, rabies virus is located within and fuses with acidic endosomes.

Adsorption↗
PubMed1998

Combined lung volume reduction and mitral valve reconstruction.

Combined lung volume reduction and mitral valve reconstruction was performed in a 66-year-old man with end-stage emphysema and severe mitral regurgitation. Quality of life, pulmonary function, 6-minute walk, echocardiographic degree of mitral regurgitation, and New York Heart Association heart failure classification all improved substantially. A lung volume reduction operation can safely be combined with complex cardiac operations for patients with disabling dyspnea of a multifactorial nature.

Aged↗
PubMed1998

B mode ultrasonography--spectrum of paediatric ocular disease.

BACKGROUND: Despite having appropriate sonographic equipment available many radiologists remain unfamiliar with B mode sonography of the eye. OBJECTIVE: This article reviews the advantages and disadvantages of B mode sonography of the paediatric eye. We illustrate the spectrum of eye abnormalities occurring in paediatric practice and the sonographic appearance of clinical entities for which sonography is appropriate. MATERIALS AND METHOD: We reviewed our experience of eye sonography within a paediatric radiology department over 8 years. A total of 212 sonographic examinations were performed on 206 eyes in 103 children, aged from 3 days to 16 years (mean 4.6 years). RESULTS: Sonography was well tolerated by the children, was a very useful imaging modality and was the only diagnostic imaging modality required in 94%. Supplementary computed tomography (CT) was performed in ten of 206 eyes (5%) and magnetic resonance imaging (MR) was performed in two of 206 eyes (1%). CONCLUSIONS: B mode sonography is a very useful imaging modality for suspected ocular or orbital pathology in children and is often the appropriate first line investigation following clinical evaluation. Radiologists familiar with sonography of the eye can provide valuable support to their ophthalmology colleagues.

Adolescent↗
PubMed1998

The experience of clients and informal caregivers with community health care services.

Persistent changes in long term care policy reform in Ontario prompted one home care program to undertake a multifaceted study to evaluate the effects of those changes. This article describes the qualitative component of the study examining perceptions of clients (persons with disabilities; adults over 80 and under 80 years of age) and of informal caregivers concerning their satisfaction with services and the impact of service delivery on their quality of life. Responses and descriptions of relevant perceptions and experiences varied with category of participant. Study findings revealed that satisfaction with services and concomitant quality of life depended upon the quality of communication with service providers.

Adult↗
PubMed1998

Rabies virus entry into cultured rat hippocampal neurons.

Rabies virus entry into cultured hippocampal neurons was investigated by immunofluorescence and electron microscopy. Hippocampal neurons were susceptible to rabies virus infection and became filled with viral antigen 1 day after infection. Infection was inhibited by the lysosomotropic agents chloroquine and ammonium chloride. To study entry, neurons were adsorbed with rabies virus at 4 degrees C and warmed to 37 degrees C for short periods of time prior to fixation and localization of viral antigen by immunofluorescence microscopy By 5 min at 37 degrees C, viral antigen was localized to puncta in the cell body and dendrites and in synapses along dendrites. Little viral antigen was present in axons. Cells adsorbed with rabies virus were incubated with tracers for early endosomes. The endocytic tracers or markers Lucifer Yellow, transferrin receptor, dextran, and wheat germ agglutinin co-localized with rabies virus, indicating that rabies virus enters an endosome compartment shortly after uptake. Rabies virus also co-localized with LysoTracker Red, an acidotropic probe, indicating that some of the virus-containing endosomes are acidified. Rabies virus also co-localized with synapsin I, a synaptic vesicle marker, in nerve terminals but did not co-localize with lysosomal glycoprotein. By electron microscopy, after adsorption of virus and warming for 10 min, virus particles were present in coated pits, coated vesicles, and vacuolar membrane compartments in processes and axon terminals. It is concluded that rabies virus enters the somatodendritic domain and axon terminals of cultured hippocampal neurons by adsorptive endocytosis and is located in endosomes shortly after uptake.

Animals↗
PubMed1998

Cell-free human immunodeficiency virus type 1 in breast milk.

Breast-feeding may be an important route of human immunodeficiency virus type 1 (HIV-1) vertical transmission in settings where it is routinely practiced. To define the prevalence and quantity of HIV-1 in cell-free breast milk, samples from HIV-1-seropositive women were analyzed by quantitative competitive reverse transcription-polymerase chain reaction (QC-RT-PCR). HIV-1 RNA was detected in 29 (39%) of 75 specimens tested. Of these 29 specimens, 16 (55%) had levels that were near the detection limit of the assay (240 copies/mL), while 6 (21%) had >900 copies/mL. The maximum concentration of HIV-1 RNA detected was 8100 copies/mL. The prevalence of cell-free HIV-1 was higher in mature milk (47%) than in colostrum (27%, P = 0.1). Because mature milk is consumed in large quantities, these data suggest that cell-free HIV-1 in breast milk may contribute to vertical transmission of HIV-1.

Adolescent↗
PubMed1998

Forgetting rates in neuropsychiatric disorders.

OBJECTIVE: Previous studies have attributed accelerated forgetting rates on recognition memory tasks to temporal lobe pathology, but findings in some patient groups may have been attributable to metabolic disruption. Findings in psychiatric disorders such as schizophrenia are conflicting. The purpose of the present study was to compare forgetting rates in patients with confusional states (post-electroconvulsive therapy (post-ECT), delirium), with those obtained in schizophrenic patients (with putative temporal lobe pathology), non-ECT depressed patients, and healthy controls. The findings could also be compared with previous reports in patients with head injury, focal structural lesions, and Alzheimer's dementia. METHODS: Two studies employed a picture recognition task to examine forgetting rates, the first between delays of 1 minute, 15 minutes, and 30 minutes, and the second between delays of 10 minutes, 2 hours, and 24 hours. RESULTS: There were no significant differences in forgetting rates between 1 minute and 30 minutes, but the ECT group showed accelerated forgetting between 10 minutes and 2 hours compared with healthy controls, associated with a rapid decline in "hit rate". This was not attributable to differential changes in either depression or severity of memory impairment. There were no differences in forgetting rates across the other subject groups. CONCLUSION: Post-ECT confusional state patients (similarly to "within post-traumatic amnesia" patients with head injury) show accelerated forgetting on a recognition memory task and, in this, they contrast with patients who have focal structural lesions or widespread cortical atrophy. Accelerated forgetting may reflect the effect of disrupted cerebral metabolism on either "consolidation" or memory "binding" processes.

Adult↗
PubMed1998

Air pollution and daily mortality in Sydney, Australia, 1989 through 1993.

OBJECTIVES: This study examined the effects of outdoor air pollutants in Sydney, Australia, on daily mortality. METHODS: Time-series analysis was performed on counts of daily mortality and major outdoor air pollutants (particulates, ozone, and nitrogen dioxide) in Sydney (1989 to 1993) with adjustment for seasonal and cyclical factors. Poisson regression was calculated with allowance for overdispersion and autocorrelation. The effects of lagging exposure by 0 to 2 days were assessed with single- and multiple-pollutant models. RESULTS: An increase in daily mean particulate concentration from the 10th to the 90th centile was associated with an increase of 2.63% (95% confidence interval 0.87 to 4.41) in all-cause mortality and 2.68% (0.25 to 5.16) in cardiovascular mortality. An increase in daily maximum 1-hour ozone concentration from the 10th to the 90th centile was associated with an increase of 2.04% (0.37 to 3.73) in all-cause mortality and 2.52% (-0.25 to 5.38) in cardiovascular mortality. An increase in the daily mean nitrogen dioxide concentration from the 10th to the 90th centile was associated with an increase of 7.71% (-0.34 to 16.40) in respiratory mortality. Multiple-pollutant models suggest that the effects of particulates and ozone on all-cause and cardiovascular mortality, and of nitrogen dioxide on respiratory mortality, are independent of the effects of the other pollutants. CONCLUSIONS: Current levels of air pollution in Sydney are associated with daily mortality.

Air Pollutants↗
PubMed1997

Positron emission tomography in male violent offenders with schizophrenia.

The FDG PET brain scans from 31 offenders with schizophrenia and schizoaffective disorder from a maximum security mental hospital were compared with those of normal controls (N = 6) in terms of relative FDG uptake in a range of regions covering frontal and temporal regions. The patient sample was divided into those who had a history of repetitive violent offending (RVO, N = 17) and those without a repetitive violent history (NRVO, N = 14) according to the violence rating of their pre-admission convictions. Reduced FDG uptake was noted at both the right and left anterior inferior temporal (R and L AIT) regions in NRVOs but only at LAIT in RVOs. NRVOs had significantly lower FDG uptake at RAIT than RVOs. The findings suggest that metabolic changes at AIT may be related to different patterns of violent offending in patients with schizophrenia.

Adult↗