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Biomedical subjects

K Chamberlain

Publications and source records attributed to K Chamberlain.

At least 19 recordsLinked to original sources
PubMed2003

Volatiles from whitefly-infested plants elicit a host-locating response in the parasitoid, Encarsia formosa.

The blend of volatile compounds emitted by bean plants (Phaseolus vulgaris) infested with greenhouse whitefly (Trialeurodes vaporariorum) has been studied comparatively with undamaged plants and whiteflies themselves. Collection of the volatiles and analysis by gas chromatography revealed more than 20 compounds produced by plants infested with whitefly. Of these, 4 compounds, (Z)-3-hexen-1-ol, 4,8-dimethyl-1,3,7-nonatriene, 3-octanone, and one unidentified compound were emitted at higher levels than from the undamaged control plants. Synthetic (Z)-3-hexen-1-ol, 4,8-dimethyl-1,3,7-nonatriene, or 3-octanone all elicited a significant increase in oriented flight and landing on the source by the parasitoid, Encarsia formosa, in wind tunnel bioassays. Two-component mixtures of the compounds and the three-component mixture all elicited a similar or, in most cases, a better response by the parasitoid, the most effective being a mixture of (Z)-3-hexen-1-ol and 3-octanone. These results demonstrate that E. formosa uses volatiles from the plant-host complex as olfactory cues for host location.

Animals↗
PubMed2001

Health psychology and the study of the case: from method to analytic concern.

This paper recommends that the study of the case be seen as of primary analytic concern to social scientists, and particularly to health psychologists. Criticism is made of the idea that a case is merely a medical instance or a methodological option. Instead, we argue that health psychologists should re-direct their attention to the 'study of the case' as being central to issues concerning health, illness and healing. There are three reasons for doing this. First, case study is basic to any procedure that involves collecting information about the context in which medicine is practiced. Second, communication between health professionals involves presenting the clinical situation of their patients as storied accounts, so that cases are made, not found. Third, there is presentational work by patients, involving communications of (as well as about) suffering and relief. This last feature is basic to how doctors and health psychologists, especially those engaged in clinical work, understand individuals as 'cases'. The paper explores differences between these different forms of case, while emphasizing portrayal as a key feature of all of them. In justifying the study of the case on conceptual as well as on clinical and methodological grounds, we highlight the position of health psychology in its attempts both to study and to intervene in health-care contexts.

Behavioral Medicine↗
PubMed2000

New roles for cis-jasmone as an insect semiochemical and in plant defense.

cis-jasmone, or (Z)-jasmone, is well known as a component of plant volatiles, and its release can be induced by damage, for example during insect herbivory. Using the olfactory system of the lettuce aphid to investigate volatiles from plants avoided by this insect, (Z)-jasmone was found to be electrophysiologically active and also to be repellent in laboratory choice tests. In field studies, repellency from traps was demonstrated for the damson-hop aphid, and with cereal aphids numbers were reduced in plots of winter wheat treated with (Z)-jasmone. In contrast, attractant activity was found in laboratory and wind tunnel tests for insects acting antagonistically to aphids, namely the seven-spot ladybird and an aphid parasitoid. When applied in the vapor phase to intact bean plants, (Z)-jasmone induced the production of volatile compounds, including the monoterpene (E)-beta-ocimene, which affect plant defense, for example by stimulating the activity of parasitic insects. These plants were more attractive to the aphid parasitoid in the wind tunnel when tested 48 h after exposure to (Z)-jasmone had ceased. This possible signaling role of (Z)-jasmone is qualitatively different from that of the biosynthetically related methyl jasmonate and gives a long-lasting effect after removal of the stimulus. Differential display was used to compare mRNA populations in bean leaves exposed to the vapor of (Z)-jasmone and methyl jasmonate. One differentially displayed fragment was cloned and shown by Northern blotting to be up-regulated in leaf tissue by (Z)-jasmone. This sequence was identified by homology as being derived from a gene encoding an alpha-tubulin isoform.

Amino Acid Sequence↗
PubMed2000

Thatch biodegradation and antifungal activities of two lignocellulolytic Streptomyces strains in laboratory cultures and in golf green turfgrass.

The use of lignocellulolytic Streptomyces spp. as biological agents, to enhance thatch degradation in turf and to slow its rate of accumulation while controlling fungal growth in the thatch layer, was studied. In flask scale studies, two lignocellulolytic Streptomyces violaceusniger (= hygroscopicus) strains (YCED9 and WYE53) decomposed thatch (> 30% dry weight) over a 12-week incubation period. Biodegradation was accompanied by production of extracellular cellulases, xylanases, and peroxidases. The accumulation of the polymeric, water-soluble lignin degradation intermediate acid, precipitable polymeric lignin (APPL), was also observed. Residual thatch from 12-week-old cultures had an increased lignin-to-carbohydrate ratio, an indication that although lignin was metabolized, carbohydrates were preferential carbon sources for these actinomycetes. A spore-containing soluble dry powder formulation was used as an inoculum in an in situ field experiment. This formulation was maintained in storage at 4 degrees C for over two years without viability loss. Results from the golf green experiment showed that although treated thatch layers in established greens were not appreciably reduced over the course of one summer, the Streptomyces were active and maintained their populations within the thatch, while fungal growth was suppressed as compared to controls. The results show that treatment of turfgrass with these Streptomyces may be useful for the long-term control of fungal populations within the thatch. Longer field studies are required to assess the long-term potential for also controlling thatch build-up and fungal pathogens.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1999

Exploiting insect responses in identifying plant signals.

Plants produce compounds which can act as semiochemicals, i.e. as signals modifying the behaviour and development of other organisms without having direct physiological activity, and which generally have extremely benign toxicological properties. Such semiochemicals include plant stress signals and possibly also phytopheromones associated with the induction of defence systems but which may also be exploited by colonizing organisms. Since it is now possible to use sophisticated electrophysiological techniques to investigate insect interactions with phytopheromones, the detection and characterization of such signalling systems is greatly facilitated, particularly when combined with behavioural techniques for confirming the biological relevance of the signals. As well as the contribution of these studies to the understanding of plant-insect and plant-plant interactions, plant signals are potentially valuable in the regulation of gene expression for improved or alternative approaches to crop protection. It would also be possible to use these signals to 'switch on', when required, other genes associated with beneficial agronomic or nutritional crop traits.

Animals↗
PubMed1999

Posttraumatic stress disorder and interpersonal functioning in Vietnam War veterans: a mediational model.

This study examines the association between posttraumatic stress disorder (PTSD) and interpersonal functioning in a New Zealand community sample of 756 Vietnam War veterans. The results support previous research findings showing that PTSD adversely affects veterans' interpersonal relationships, family functioning, and marital/dyadic adjustment and show that the effects of PTSD on family functioning and dyadic adjustment are mediated by severity of interpersonal problems. It is suggested that higher levels of PTSD affect the ability of veterans to initiate and maintain interpersonal relationships and that these interpersonal problems are evident in poorer levels of family functioning and poorer dyadic adjustment.

Combat Disorders↗
PubMed1999

In vitro and in vivo antagonism of pathogenic turfgrass fungi by Streptomyces hygroscopicus strains YCED9 and WYE53.

Disease prevention is a current practice used to minimize fungal diseases of turfgrasses in lawns and golf greens. Prevention is accomplished through fungicide applications, and by periodic thatch removal. During the development of a microbial biodethatch product utilizing the lignocellulose-degrading Streptomyces hygroscopicus strains YCED9 and WYE53, we demonstrated using in vitro plate antagonism bioassays that both strains are antagonists of various turfgrass fungal pathogens. These activities were present when the cultures were growing on thatch, as demonstrated by antifungal antagonism bioassays with culture filtrates. Experiments conducted using a growth chamber demonstrated that a bio-dethatch formulation containing spores of strains YCED9 and WYE53 in a zeolite carrier, provided protection for Kentucky bluegrass seedlings against turfgrass pathogens, including Pythium ultimum, Fusarium oxysporum, Rhizoctonia solani, Sclerotinia homeocarpa, Gaeumannomyces graminis and Microdochium nivale. Results showed that by integrating the use of the S. hygroscopicus YCED9/WYE53 bio-dethatch formulation into routine turf management practices, it should be possible to both minimize thatch build-up while also controlling fungal turfgrass diseases by way of the antifungal biocontrol activity of these strains. This in turn would help control fungal pathogens in turfgrass while minimizing the need for routine chemical fungicide applications.

Fungi↗
PubMed1998

Mental health, physical health, and stressors reported by New Zealand Defence Force peacekeepers: a longitudinal study.

The psychological effect of peacekeeping duties on 277 New Zealand Defence Force personnel was investigated using a longitudinal, cross-sectional study. Self-report data were collected in five stages from before deployment to approximately 6 months after return. Multiple measures of mental health, physical health, and stressors were used. Results revealed that the most stressful periods of the deployment, and those with the greatest effect on overall health and well-being, appear to be the predeployment and follow-up stages. These findings demonstrate the need for effective predeployment training and postdeployment debriefing and support.

Adult↗
PubMed1997

Race, combat, and PTSD in a community sample of New Zealand Vietnam War veterans.

The association between posttraumatic stress disorder (PTSD), combat exposure, and race was examined in a New Zealand community sample of 756 Vietnam War veterans. Maori veterans reported higher levels of PTSD than their non-Maori counterparts. However, the race effect was shown to be mediated by combat exposure level, rank, and combat role. These findings support differential experience explanations for the relationship between postwar adjustment and race, suggesting that higher levels of psychological symptoms reported by minority group veterans can be accounted for by their experience of higher levels of combat stressors.

Adaptation, Psychological↗
PubMed1997

Structure of music may influence cognition.

Classical music has been said to enhance cognition, which effect may be related to musical structure. 19 subjects who listened to highly structured music scored somewhat higher afterwards on cognitive performance than the 15 who listened to less structured music. Since this did not reach statistical significance, other as yet unidentified factors may also be involved.

Acoustic Stimulation↗
PubMed1996

Cynical hostility, anger, and resting blood pressure.

Research on associations of anger and hostility with resting blood pressure (BP) has generally ignored their interrelationships. The present study examined the individual and joint relationships of cynical hostility, anger-in, anger-out, and anger frequency with resting BP using the Cook-Medley Hostility Scale and the Spielberger anger scales. Multiple regressions were conducted on data from a community sample of 105 men and women to examine the main and interactive effects of anger and hostility on BP, controlling for established physical covariates. Diastolic BP was inversely related to anger-in scores in men and women. Systolic and diastolic BP were positively associated with Ho (hostility) score only in women. No confounding or interactive effects of hostility and anger on BP were found. It is suggested that the sex-specific link between cynical hostility and BP may reflect a chronic mismatch between the social cognitions of cynically hostile women and some of the cultural norms that govern women's social lives.

Adult↗
PubMed1996

Dimensions of life meaning: a qualitative investigation at mid-life.

Meaning in life is integral to psychological functioning. Empirical research into this construct has focused on sources of meaning. Reker & Wong (1988) have proposed a theoretical outline for a multidimensional structure of meaning which challenges a source-based approach. The present study used a qualitative approach to explore people's accounts of their experiences of life meaning and focused on the following key dimensions: sources; cognitive, motivational and affective components; breadth; and depth. Thirty-eight adults at mid-life were interviewed in depth. Five categories of sources accounted for material reported in previous studies, but a sixth was required to contain experiences of meaning relating to the natural environment. All sources revealed cognitive, motivational and affective components. Accounts showed variation in breadth and depth of meaning, although the assessment of depth proved problematic. Results from this qualitative exploration generally confirm Reker & Wong's structural model. Furthermore, many people have coherent frameworks of meaning which structure their life experiences, and serve to integrate these theoretical dimensions.

Adult↗
PubMed1996

Prevalence of posttraumatic stress disorder, depression and anxiety in a community sample of New Zealand Vietnam War veterans.

OBJECTIVE: The aim of the paper is to investigate the prevalence of posttraumatic stress disorder (PTSD), depression and anxiety in a community sample of New Zealand Vietnam War veterans. METHOD: Data were collected as part of a national survey on the health and mental health of New Zealand Vietnam veterans. Five hundred and seventy-three randomly selected male Vietnam veterans participated in a postal survey. The questionnaire contained a number of demographic, biographical and psychological measures. RESULTS: The results revealed that 10% of the veterans could be classified as PTSD cases and that these veterans exhibited high levels of depression and anxiety. In PTSD cases, 15% were also classified with anxiety, 6% with depression, and 73% were classified with both anxiety and depression. In PTSD cases 94% were classified with more than one additional disorder. In non-PTSD cases 27% were classified with anxiety, and 1% with depression, while 12% experienced both anxiety and depression. CONCLUSIONS: The consequences of comorbidity for research and treatment are discussed and it is suggested that health professionals should be attentive to military experience as a predictor of these disorders.

Adult↗
PubMed1994

Self management practices in adult asthmatics.

AIM: To examine how adherence to medications and use of competencies (eg, avoiding personal precipitants and managing an acute attack) vary by age, sex, education and number of symptoms in a sample of adult asthmatics. METHODS: 412 adult asthmatics, members of two asthma societies, participated in a mailed survey. The questionnaire contained measures of asthma medication adherence, asthma health competencies, asthma symptoms, and demographic characteristics. RESULTS: Older asthmatics were more likely to adhere and to use more competencies. Females used more competencies than males. Asthmatics with higher numbers of symptoms used more competencies. No differences were found by educational level. CONCLUSIONS: Better adherence in older asthmatics may be due to their having developed greater recognition of the efficacy of medications. The more extensive use of competencies by older people and by women reflects previous findings that these groups value health more and engage in less health threatening behaviours in general. The results also suggest that experiencing asthma symptoms motivates better self management practices. The study raises awareness of the role of competencies in controlling asthma, and should assist health professionals to identify specific differences in self management.

Adult↗
PubMed1994

Effect of the Gulf War on reactivation of adverse combat-related memories in Vietnam veterans.

Symptoms of combat related posttraumatic stress disorder (PTSD) have been reported extensively in Vietnam veterans. A few of these studies have reported situations in which PTSD has been reactivated in veterans with a history of PTSD. The present study reports the effects of media coverage of the Gulf War on a community sample of New Zealand Vietnam veterans. Levels of PTSD, distress, and well-being were assessed before and after the outbreak of hostilities. Most veterans closely followed the media presentation of the war and reported revived memories of Vietnam. Increased memories of Vietnam were associated with higher levels of PTSD and distress. It is suggested that veterans have heightened susceptibility to combat related stimuli because of their previous combat experience and that these stimuli can reactivate PTSD symptoms and distress. Implications of this finding for other groups in the community who harbour residual PTSD effects are discussed.

Adult↗
PubMed1994

The psychological impact of hip arthroplasty.

The impact of total hip arthroplasty on psychological functioning was examined in 51 patients; 25 females and 26 males with a mean age of 65 years (range 42-81 years). Assessments of psychological well-being and distress were made with the Mental Health Inventory. Life satisfaction, self-rated health, and pain ratings were also obtained. Assessments were made prior to surgery, immediately after surgery, and at a 2 month follow-up. The operation produced significant improvements in psychological well-being (P < 0.001), psychological distress (P < 0.001), life satisfaction (P < 0.01), self-rated health (P < 0.001), and pain (P < 0.001). It is concluded that the changes in medical and functional status following hip arthroplasty documented in previous research are accompanied by substantial improvements in psychological state, and that the inclusion of psychological factors in hip arthroplasty research will provide a more comprehensive assessment of outcome.

Adaptation, Psychological↗