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Biomedical subjects

L Waite

Publications and source records attributed to L Waite.

11 recordsLinked to original sources
PubMed2000

How is household vulnerability gendered? Female-headed households in the collectives of Suleimaniyah, Iraqi Kurdistan.

This research tries to reach an understanding of the well-being of female-headed household members through a comparison to male-headed household members in the collectives of the Suleimaniyah governorate in Iraqi Kurdistan. Research was undertaken in five collectives in Suleimaniyah during the summer of 1998. The research contributes to the current gender and development debates which are concerned with improving the understanding of the specific gendered forms of disadvantage faced by female-headed households rather than assuming the universal poverty of this group. An understanding of well-being is approached through a broad conceptualisation of vulnerability in preference to a narrow poverty definition. That the findings of this research are complex attests to the multi-dimensional and mutually constitutive gendered experiences of vulnerability. The definitive conclusion to emerge from this research is a refuting of the rhetoric-fuelled stereotype that households headed by women are at a disadvantage in all the dimensions of vulnerability in comparison to households headed by men. The research also establishes the methodological necessity of examining intra-household distributive mechanisms that determine individuals' well-being.

Developing Countries↗
PubMed2000

Long-term benzodiazepine use by elderly people living in the community.

OBJECTIVE: To investigate the prevalence of long-term benzodiazepine use in an elderly community sample, and factors associated with such use. METHOD: Data came from the Sydney Older Persons Study, a longitudinal study of people aged 75 or over. There were 337 subjects who were interviewed in 1991-93, and subsequently followed up after three and 4.5 years. At the first interview, subjects were assessed for socio-demographic characteristics, physical and mental health, and use of health services. At the first and subsequent interviews, subjects were asked about use of medications, including benzodiazepines. RESULTS: There were 16.6% who were using benzodiazepines at the time of all three interviews, while a further 19.6% were using them at one or two interviews. In a multivariate ordered logit regression model, long-term benzodiazepine use was associated with treatment for nervous conditions, restless sleep, being female, being divorced and greater contact with medical services. CONCLUSIONS: The prevalence of benzodiazepine use in the elderly is high and much of this use is long term. The high prevalence of benzodiazepine use stands in contrast to the findings from national surveys that the elderly living in the community tend to have better mental health than younger age groups. IMPLICATIONS: Efforts are needed to reduce the number of elderly people becoming long-term users. The use of benzodiazepines in this age group is of particular concern, because they may be a risk factor for falls and for cognitive impairment in the elderly.

Aged↗
PubMed2000

A lumped parameter model of left ventricular filling-pressure waveforms.

Assessment of left-ventricular function and quantification of valve stenosis are important in clinical practice as well as in physiological research. This paper describes a mathematical model of diastolic ventricular filling and flow across the mitral valve. The model primarily consists of a system of three first-order, non-linear ordinary differential equations. The equations are solved in MATLAB using the ode45 command. The model generates pressure versus time waveforms for the atrium and ventricle, and flow versus time waveforms for mitral valve flow. Comparisons between model outputs and in-vivo data collected in two porcine experiments show excellent agreement.

Diastole↗
PubMed1999

Carer distress in the general population: results from the Sydney Older Persons Study.

OBJECTIVE: To assess distress in a sample of carers who were selected from a community survey rather than recruited via community-service agencies. METHODS: A community survey was carried out on 630 people aged 75 or over living in Sydney, Australia. Informants nominated by these elderly people were divided into full carer (n = 21), partial carer (n = 187) and non-carer groups (n = 344). Informants completed the General Health Questionnaire (a continuous measure of psychiatric symptoms), the life satisfaction index (a measure of well-being) and the interpersonal bonding measure (a measure of quality of the relationship with the elderly person). Elderly participants had a medical examination, were assessed for disability and were questioned about use of services. RESULTS: Elderly people who had a full carer were more disabled and had more medical diagnoses. Full, but not partial, carers reported more psychiatric symptoms and lower life satisfaction. In multivariate analysis, the main determinant of carer distress was a relationship in which the carer felt controlled by the elderly person. CONCLUSION: When carers are selected from a population-based sample, only those who are full carers are more distressed. However, relationship factors are the most important determinant of distress.

Activities of Daily Living↗
PubMed1999

Informant-based staging of dementia using the clinical dementia rating.

The staging of dementia is ideally based on both an examination of the patient and a history taken from an informant. However, in some circumstances, only an informant history is possible. The aim of this study was to assess the validity of the Clinical Dementia Rating (CDR) when the rating is based solely on informant data. The CDR was used in a study of 360 persons aged 78 or older who were participants in a community survey, the Sydney Older Persons Study. The CDR was completed in two ways: (1) a social scientist made the ratings based on an informant interview; and (2) a physician made the ratings after an examination of the subject. All CDRs were scored in the conventional way, as well as by the revised method proposed by Gelb and St. Laurent (Alzheimer Dis Assoc Disord 1993;4:202-11). The informant CDR showed moderate agreement with the clinician CDR, showing that it would be a valid substitute in situations in which the subject could not be examined. The revised scoring method was slightly easier to implement than the conventional method.

Aged↗
PubMed1999

Pseudomonas aeruginosa gene products PilT and PilU are required for cytotoxicity in vitro and virulence in a mouse model of acute pneumonia.

Type IV pili of the opportunistic pathogen Pseudomonas aeruginosa mediate twitching motility and act as receptors for bacteriophage infection. They are also important bacterial adhesins, and nonpiliated mutants of P. aeruginosa have been shown to cause less epithelial cell damage in vitro and have decreased virulence in animal models. This finding raises the question as to whether the reduction in cytotoxicity and virulence of nonpiliated P. aeruginosa mutants are primarily due to defects in cell adhesion or loss of twitching motility, or both. This work describes the role of PilT and PilU, putative nucleotide-binding proteins involved in pili function, in mediating epithelial cell injury in vitro and virulence in vivo. Mutants of pilT and pilU retain surface pili but have lost twitching motility. In three different epithelial cell lines, pilT or pilU mutants of the strain PAK caused less cytotoxicity than the wild-type strain but more than isogenic, nonpiliated pilA or rpoN mutants. The pilT and pilU mutants also showed reduced association with these same epithelial cell lines compared both to the wild type, and surprisingly, to a pilA mutant. In a mouse model of acute pneumonia, the pilT and pilU mutants showed decreased colonization of the liver but not of the lung relative to the parental strain, though they exhibited no change in the ability to cause mortality. These results demonstrate that pilus function mediated by PilT and PilU is required for in vitro adherence and cytotoxicity toward epithelial cells and is important in virulence in vivo.

Adenosine Triphosphatases↗
PubMed1997

Automatic determination of patellofemoral kinematic parameters through X-ray image processing.

Examination of plain Merchant-view X-rays of the patellofemoral joint is often used to diagnose patellofemoral joint malalignment and to qualify the pathology. As digital image processing becomes more widespread, an image processing algorithm is being developed for medical personnel to easily display, manipulate and analyze digitized plain Merchant-view X-ray films on personal computers. The method provides measurement of the kinematic parameters: sulcus angle (SA), patellofemoral congruence angle (PFC), lateral patellar angle (LPA), patellar rotation angle (PR), and lateral patellar displacement (LPD). Smooth edges of the patella and the femur are obtained by using image enhancement, edge detection and morphological thinning techniques based on the thresholds chosen manually for boundary detection. Six landmarks for determining the kinematic parameters are marked automatically on the edges of patella and femur. Parameter measurements for twelve X-ray films of six patients are calculated for analysis and comparison with hand calculated parameters. The goal is develop an algorithm that can evaluate the geometry of the patellofemoral joint, and is cost effective.

Femur↗
PubMed1996

Nongenomic effects of progesterone on human intestinal smooth muscle cells.

Previous experiments demonstrated that progesterone affects intestinal smooth muscle cells through genomic and nongenomic pathways. We hypothesized that the nongenomic effect was mediated by changes in membrane excitability. We studied the effects of progesterone and other steroid hormones on a human intestinal smooth muscle cell line, using the whole cell patch-clamp technique. Ionic currents were elicited through steps from -70 mV to various test potentials. Progesterone dose-dependently reduced calcium currents. The decrease in inward current was partly due to a shift in the steady-state inactivation to more hyperpolarized potentials. This effect did not involve gene transcription, since it was not blocked by the progesterone antagonist ZK-98-299. The progesterone analogue 5-beta-dihydroprogesterone also decreased calcium currents, whereas its stereoisomer, 5-alpha- dihydroprogesterone, did not affect the properties of voltage-sensitive ion channels. Similarly, estradiol and dexamethasone did not alter inward currents. We conclude that progestins exert their nongenomic effects on intestinal smooth muscle cells by decreasing calcium currents. The change in the calcium signal may contribute to the reduction in muscle contraction observed after progesterone.

Cells, Cultured↗
PubMed1996

Patellofemoral joint study via image processing.

Plain Merchant-view X-rays of patellofemoral joints are used to study the geometry and kinematics of the patellofemoral joint. A method for calculating the kinematic parameters: sulcus angle (SA), patellofemoral congruence angle (PFC), lateral patellar angle (LPA), patellar rotation angle (PR) and lateral patellar displacement (LPD) is presented. Using digitized X-ray images of patellofemoral joints, contours of the patella and the femur can be acquired by boundary detection and morphological thinning. A radiograph is converted to a line drawing and the data points required for calculation of the parameters are chosen automatically without human intervention. Parameter measurements were demonstrated for 5 X-rays of 3 patients. Comparisons between computer calculated and hand calculated parameters were made. This technique is inexpensive but will provide the necessary information, and is practical, especially during the evaluation of patients with patellofemoral abnormalities.

Femur↗
PubMed1991

Mechanical characteristics and active tension generation in rat intestinal arterioles.

The contributions of active and passive wall tension to regulation of arteriolar diameters were determined for large (1A), intermediate (2A), and small (3A) arterioles in the small intestine of the anesthetized rat. Active tension (Ta) contributed greater than 85% of total wall force at rest in 2A and 3A and 75-80% of total force in 1A. Ta was approximately 90% of peak active tension (Ta,peak) for large through small arterioles, even though absolute Ta varied by fourfold. A linear relationship between microvascular pressure and Ta was observed for decreases in pressure in all arterioles. Ta remained nearly constant for pressure increases of 40% in 2A and 3A but was increased in 1A. Because of the plateau of the circumference-Ta relationship near Ta,peak, superfusion of progressively increasing concentrations of norepinephrine or adenosine resulted in maintenance of the close Ta-Ta,peak relationship unless the vessel diameter changed greater than 25%. These results indicate that, while arteriolar diameters vary substantially, near-peak Ta is generated for a variety of physiological conditions.

Adenosine↗