PubMed Health⌕ Search

Biomedical subjects

J Hiller

Publications and source records attributed to J Hiller.

At least 19 recordsLinked to original sources
PubMed2001

Microfocus small angle X-ray scattering reveals structural features in archaeological bone samples: detection of changes in bone mineral habit and size.

Microfocus X-ray scattering provides a powerful nondestructive technique capable of providing important information about the size, habit, and arrangement of mineral crystals in bone. The technique is capable of probing textural differences in a sample at a micron scale resolution. The study presented here involved the analysis of a number of archaeological bones by microfocus X-ray scattering at the ESRF Grenoble in order to determine local changes in mineral durability. The results showed that regions of bone with a modified microscopic morphology contained a greater dispersion of crystal shape when compared with more intact regions and control contemporary bone samples, but the crystal thickness values showed similar consistency. We speculate that the persistence of collagen in the archaeological bone may allow diagenetic remodeling of bone in terms of crystallite shape but defines the size of remodelled crystallites. The ability to detect such local changes in texture has wide potential for determining crystal characteristics in healthy and diseased bone samples.

Archaeology↗
PubMed2001

Variation in mortality rates in Australia: correlation with Indigenous status, remoteness and socio-economic deprivation.

BACKGROUND: The aim of this study was to study ecological correlations between age-adjusted all-cause mortality rates in Australian statistical divisions and (1) the proportion of residents that self-identify as Indigenous, (2) remoteness, and (3) socio-economic deprivation. METHODS: All-cause mortality rates for 57 statistical divisions were calculated and directly standardized to the 1997 Australian population in 5-year age groups using Australian Bureau of Statistics (ABS) data. The proportion of residents who self-identified as Indigenous was obtained from the 1996 Census. Remoteness was measured using ARIA (Accessibility and Remoteness Index for Australia) values. Socioeconomic deprivation was measured using SEIFA (Socio-Economic Index for Australia) values from the ABS. RESULTS: Age-standardized all-cause mortality varies two-fold from 5.7 to 11.3 per 1,000 across Australian statistical divisions. Strongest correlation was between Indigenous status and mortality (r = 0.69, p < 0.001). Correlation between remoteness and mortality was modest (r = 0.39, p = 0.002) as was correlation between socio-economic deprivation and mortality (r = -0.42, p = 0.001). Excluding the three divisions with the highest mortality, a multiple regression model using the logarithm of the adjusted mortality rate as the dependent variable showed that the partial correlation (and hence proportion of the variance explained) for Indigenous status was 0.03 (9 per cent; p = 0.03), for SEIFA score was -0.17 (3 per cent; p = 0.22); and for remoteness was -0.22 (5 per cent; p = 0.13). Collectively, the three variables studied explain 13 per cent of the variability in mortality. CONCLUSIONS: Ecological correlation exists between all-cause mortality, Indigenous status, remoteness and disadvantage across Australia. The strongest correlation is with Indigenous status, and correlation with all three characteristics is weak when the three statistical divisions with the highest mortality rates are excluded. Intervention targeted at these three statistical divisions could reduce much of the variability in mortality in Australia.

Australia↗
PubMed2000

An adaptive nonlinear diffusion algorithm for filtering medical images.

The nonlinear anisotropic diffusive process has shown the good property of eliminating noise while preserving the accuracy of edges and has been widely used in image processing. However, filtering depends on the threshold of the diffusion process, i.e., the cut-off contrast of edges. The threshold varies from image to image and even from region to region within an image. The problem compounds with intensity distortion and contrast variation. We have developed an adaptive diffusion scheme by applying the Central Limit Theorem to selecting the threshold. Gaussian distribution and Rayleigh distribution are used to estimate the distributions of visual objects in images. Regression under such distributions separates the distribution of the major object from other visual objects in a single-peak histogram. The separation helps to automatically determine the threshold. A fast algorithm is derived for the regression process. The method has been successfully used in filtering various medical images.

Algorithms↗
PubMed2000

Mortality variation across Australia: descriptive data for states and territories, and statistical divisions.

OBJECTIVE: To describe variation in all cause and selected cause-specific mortality rates across Australia. METHODS: Mortality and population data for 1997 were obtained from the Australian Bureau of Statistics. All cause and selected cause-specific mortality rates were calculated and directly standardised to the 1997 Australian population in 5-year age groups. Selected major causes of death included cancer, coronary artery disease, cerebrovascular disease, diabetes, accidents and suicide. Rates are reported by statistical division, and State and Territory. RESULTS: All cause age-standardised mortality was 6.98 per 1000 in 1997 and this varied 2-fold from a low in the statistical division of Pilbara, Western Australia (5.78, 95% confidence interval 5.06-6.56), to a high in Northern Territory--excluding Darwin (11.30, 10.67-11.98). Similar mortality variation (all p < 0.0001) exists for cancer (1.01-2.23 per 1000) and coronary artery disease (0.99-2.23 per 1000), the two biggest killers. Larger variation (all p < 0.0001) exists for cerebrovascular disease (0.7-11.8 per 10,000), diabetes (0.7-6.9 per 10,000), accidents (1.7-7.2 per 10,000) and suicide (0.6-3.8 per 10,000). Less marked variation was observed when analysed by State and Territory, but Northern Territory consistently has the highest age-standardised mortality rates. CONCLUSIONS: Analysed by statistical division, substantial mortality gradients exist across Australia, suggesting an inequitable distribution of the determinants of health. Further research is required to better understand this heterogeneity.

Age Factors↗
PubMed1998

Identifying donor concerns to increase live organ donation.

Increasing organ donation from live donors is a means to increase the pool of kidneys available for transplantation. To increase the number of live kidney donors, the major concerns of donors must be determined and addressed. This article describes the health and socioeconomic concerns of 61 live kidney donors from the Johns Hopkins Institutions between February 1, 1995 and December 1, 1997. Seventy-five percent of donors reported they had concerns, the most common ones being the effect of donation on their future health, how many work days they would miss, the ability to return to the same activities, and the pain they would experience. Other reported concerns consisted of fear of dying, the risks to a future pregnancy with one kidney, the fear that a son or daughter may need a kidney in the future, and the impact of donation on the family health insurance premium. Interventional strategies including the use of the laparoscopic donor nephrectomy procedure are offered to address these concerns.

Absenteeism↗
PubMed1997

Laparoscopic assisted live donor nephrectomy--a comparison with the open approach.

Live donor renal transplantation provides significant advantages when compared with cadaveric donor renal transplantation in terms of improved patient and graft survival, a lower incidence of delayed function, and a shorter waiting time. Yet despite these advantages, live donors continue to be an under utilized source of kidneys for transplantation. Disincentives to live donation include the length of hospitalization, postoperative pain, cosmetic concerns, and the prolonged convalescence associated with the donor operation. In many instances minimally invasive video-assisted techniques have proven more efficacious than standard open procedures in terms of patient discomfort, length of hospital stay, cost, and length of time until the patient can return to full activity. Laparoscopic live donor nephrectomies are being performed at our institution in an attempt to make live donation more attractive to the potential donor. The purpose of this study was to retrospectively review the results of laparoscopic live donor nephrectomy (LapNx) and to compare them with those obtained using the standard open approach (OpenNx). Ten consecutive LapNx were performed from February 1995 through April 1996. The control group consisted of the 20 consecutive OpenNx performed at the same institution from January 1991 through January 1995 immediately before the initiation of the LapNx program. Live donors were considered candidates for LapNx if they possessed at least one kidney with normal renal anatomy with single renal vessels and a single ureter. LapNx was safely performed in all cases. No patients required open conversion or blood transfusions. The allograft warm ischemic time for the laparoscopic cases was 4.2+/-1.3 min. All kidneys harvested laparoscopically produced urine on the table immediately upon revascularization. Presently nine of the ten recipients have functioning allografts. At three months posttransplant the calculated recipient creatinine clearances were 67.0+/-11.5 ml/min and 64.8+/-21.4 ml/min for the LapNx and OpenNx groups, respectively (P=NS). The LapNx donors had a significantly decreased estimated blood loss, shorter time until resumption of oral intake, decreased postoperative pain (in terms of decreased analgesic requirements), shorter hospitalization, and a shorter interval until the resumption of full activities (P<0.05 for all). In addition, the LapNx group donors returned to work sooner than the OpenNx group (3.9+/-1.6 wk vs. 6.4+/-3.1 wk, respectively) (P=0.024). Four individuals agreed to donate a kidney only after learning of the availability of the laparoscopic approach. We conclude that laparoscopic live donor nephrectomy is technically feasible. In addition, it may offer significant advantages over the standard open approach in terms of patient comfort and convenience. These advantages may make live donor renal transplantation more attractive to prospective donors. The potential decrease in hospitalization and convalescence may also prove to be financially advantageous. We believe that further careful study of this procedure is warranted.

Adult↗
PubMed1997

Method for segmenting chest CT image data using an anatomical model: preliminary results.

We present an automated, knowledge-based method for segmenting chest computed tomography (CT) datasets. Anatomical knowledge including expected volume, shape, relative position, and X-ray attenuation of organs provides feature constraints that guide the segmentation process. Knowledge is represented at a high level using an explicit anatomical model. The model is stored in a frame-based semantic network and anatomical variability is incorporated using fuzzy sets. A blackboard architecture permits the data representation and processing algorithms in the model domain to be independent of those in the image domain. Knowledge-constrained segmentation routines extract contiguous three-dimensional (3-D) sets of voxels, and their feature-space representations are posted on the blackboard. An inference engine uses fuzzy logic to match image to model objects based on the feature constraints. Strict separation of model and image domains allows for systematic extension of the knowledge base. In preliminary experiments, the method has been applied to a small number of thoracic CT datasets. Based on subjective visual assessment by experienced thoracic radiologists, basic anatomic structures such as the lungs, central tracheobronchial tree, chest wall, and mediastinum were successfully segmented. To demonstrate the extensibility of the system, knowledge was added to represent the more complex anatomy of lung lesions in contact with vessels or the chest wall. Visual inspection of these segmented lesions was also favorable. These preliminary results suggest that use of expert knowledge provides an increased level of automation compared with low-level segmentation techniques. Moreover, the knowledge-based approach may better discriminate between structures of similar attenuation and anatomic contiguity. Further validation is required.

Computer Simulation↗
PubMed1997

Functional advantages of laparoscopic live-donor nephrectomy compared with conventional open-donor nephrectomy.

Live-donor kidney transplants accounted for only 27% of all kidney transplants performed in the United States in 1995. Prolonged hospitalization, pain, extended convalescence, and related socioeconomic concerns associated with traditional open-donor nephrectomy surgery may discourage potential donors, contributing to a low percentage of live kidney donors. To remove such disincentives, the laparoscopic live-donor nephrectomy procedure was introduced. In this study, the post-discharge course of 10 laparoscopic nephrectomy donors was compared with that of 27 open nephrectomy donors over the same time period. Laparoscopic nephrectomy donors experienced significantly shorter hospitalizations, less pain, felt able to return to work and normal routines sooner, and needed significantly less assistance during the recuperation period than did open nephrectomy donors. The laparoscopic nephrectomy procedure may decrease many of the concerns of potential donors, thus making live kidney donation more attractive and increasing the kidney supply.

Activities of Daily Living↗
PubMed1996

[Mobile blood gas and laboratory monitoring. A new technology in clinical routine].

INTRODUCTION: Decision-making on therapy in acute cases involves clinical examination and monitoring of vital parameters and fluid balance; especially, however, laboratory parameters. The present study compared the results of a new bedside laboratory analysis system (PortLab, i-STAT Corp., Princeton NJ) with the analytical results obtained in our central laboratory. In a second phase personnel costs and turnover times of the two methods were evaluated comparatively. MATERIALS AND METHODS: The PortLab system consists of a basic unit (539 g) with an integrated display and disposable silicon cartridges with thin-film electrodes. Up to 8 parameters can be determined simultaneously in 60 microliters of whole blood. Fifty results obtained with the PortLab system of the parameters sodium, potassium, chlorid, glucose, BUN, hematocrit, the calculated haemoglobin and blood gas analysis were correlated with the results obtained by central laboratory analysis. In a second phase, all procedural steps, the time needed and the turnover times for laboratory analysis were compared with the expenditure for the same analyses performed with the PortLab system. RESULTS AND DISCUSSION: The results obtained using PortLab analysis correlated very well with those of the central laboratory (between 0.966 for the hematocrit and 0.994 for pO2). Three steps were required to perform bedside analysis with the PortLap system. The staff was occupied for 1 min. and 15 sec. and the results were ready within 4 min. and 45 sec. (pure analysis time < 2 min.). Analysis in the central laboratory required 8 steps, the intensive care staff was occupied for 6 min. and 15 sec., 5 min. and 15 sec. of which they were away from the patients' side. Analysis of blood gases required 4 steps, the result was ready in 4 min. 15 sec. The personnel was occupied for an equally long time. The use of PortLab saved personnel resources of 5 minutes per laboratory analysis and 3 minutes per blood gas analysis. CONCLUSION: The PortLab system proved easy to handle and reliable. Valuable personnel resources can be saved. This method cannot replace conventional laboratory analyses, but enables more extensive monitoring of patients and their laboratory parameters. The industry should develop analogous monitoring systems for modular solutions.

Blood Chemical Analysis↗
PubMed1995

Automatic identification of gray matter structures from MRI to improve the segmentation of white matter lesions.

The segmentation of MRI scans of patients with white matter lesions (WML) is difficult because the MRI characteristics of WML are similar to those of gray matter. Intensity-based statistical classification techniques misclassify some WML as gray matter and some gray matter as WML. We developed a fast elastic matching algorithm that warps a reference data set containing information about the location of the gray matter into the approximate shape of the patient's brain. The region of white matter was segmented after segmenting the cortex and deep gray matter structures. The cortex was identified by using a three-dimensional, region-growing algorithm that was constrained by anatomical, intensity gradient, and tissue class parameters. White matter and WML were then segmented without interference from gray matter by using a two-class minimum-distance classifier. Analysis of double-echo spin-echo MRI scans of 16 patients with clinically determined multiple sclerosis (MS) was carried out. The segmentation of the cortex and deep gray matter structures provided anatomical context. This was found to improve the segmentation of MS lesions by allowing correct classification of the white matter region despite the overlapping tissue class distributions of gray matter and MS lesion.

Algorithms↗
PubMed1995

Thyrotropin-releasing hormone: does two hundred micrograms provide effective stimulation to the preterm fetal pituitary gland compared with four hundred micrograms?

OBJECTIVE: Our purpose was to compare the response of the fetal pituitary-thyroid axis to 200 and 400 micrograms of thyrotropin-releasing hormone administered to the mother immediately before delivery with a control group. STUDY DESIGN: A randomized controlled trial was conducted of 26 women at gestational ages between 24 weeks and 33 weeks 6 days who had received one or more doses of betamethasone who were expected to be delivered within 1 to 4 hours. Women received either 200 or 400 micrograms of thyrotropin-releasing hormone or were in the control group. RESULTS: Thyroid-stimulating hormone determinations on cord blood had a higher mean level in both treatment groups compared with the control group. No differences were seen in cord blood results between the two treatment groups for thyroid-stimulating hormone, thyroxine, triiodothyronine, free thyroxine, free triiodothyronine, and prolactin levels. The only other differences found were in a higher level in total thyroxine and a lower level of free thyroxine in the 400 micrograms thyrotropin-releasing hormone group compared with the 200 micrograms group in the 48-hour blood determinations. CONCLUSION: Both 200 and 400 micrograms of thyrotropin-releasing hormone provided fetal pituitary stimulation, as reflected in fetal thyroid-stimulating hormone levels in cord blood, and both gave significantly higher levels compared with a control group.

Adult↗
PubMed1995

Routine stresses in caring for a child with cystic fibrosis.

Difficulties experienced by mothers caring for a child with cystic fibrosis were assessed. Difficulties were categorized as: (1) developmental, which included tasks generic to all families (bedtimes, socialization, siblings and communication with others); and (2) illness, which were especially pertinent to the care of the child with cystic fibrosis (mealtimes, physiotherapy and home-based medical care). Age differences were found in stresses associated with developmental routines, with mothers of younger children reporting more difficulties. With regard to illness routines, more difficulties were reported for children in better health (higher Shwachman scores). The data suggest that parents experience increasing difficulties in implementing home-based medical care where the child is in better health. Clinic staff need to be more aware of these difficulties and target information to parents appropriately.

Activities of Daily Living↗
PubMed1995

Screening for colorectal cancer: what are the costs?

We examined a screening program for colorectal cancer in South Australia in terms of its overall direct costs to society and costs to participants. The best estimate of the cost per cancer detected was $18,924 (Australian dollars). Potential improvements in health outcome through screening are discussed in light of these costs.

Colorectal Neoplasms↗
PubMed1994

The epidemiology of blindness and trachoma in the Anangu Pitjantjatjara of South Australia.

OBJECTIVE: To determine the prevalence of trachoma and blindness in the Aboriginal population in the Anangu Pitjantjatjara and Yalata lands of South Australia. DESIGN AND SETTING: A population-based prevalence survey undertaken in conjunction with routine South Australian Aboriginal Trachoma and Eye Health Program trips during 1989 and 1990. RESULTS: A group of 1514 individuals aged 0-90 years, or approximately 58% of the estimated Aboriginal population in the Anangu Pitjantjatjara and Yalata lands, was examined. Active inflammatory trachoma was found in 17.6% of the group (266 individuals), cicatricial trachoma in 25.2% (382) and binocular blindness (Australian definition) in 1.5% (22). The major causes of monocular and binocular blindness were trachoma, cataracts and trauma. Two per cent of women (17 of 849) were blind, compared with 0.8% (5 of 665) of men (odds ratio, 3.22; 95% confidence interval, 1.03-10.43). CONCLUSIONS: Although trachoma is still endemic in the "traditional" Aboriginal population of SA, its prevalence and severity appear to be less than previously recorded. However, the prevalence of blindness is comparable with that found in developing countries and the causes are still largely preventable. Further effort is required to reduce trachoma and preventable or treatable blindness in these communities.

Adolescent↗
PubMed1994

Screening for colorectal cancer. Knowledge, attitudes and practices of South Australian GPs.

OBJECTIVE: To examine knowledge, attitudes and practices of South Australian general practitioners (GPs) in relation to screening for colorectal cancer. DESIGN: A descriptive study in which data were collected by means of postal questionnaires. MAIN OUTCOME MEASURES: Use of screening tests for colorectal cancer, knowledge in relation to colorectal cancer prevention, opinions on organisation and delivery of colorectal cancer screening. RESULTS: The response rate to the survey was 66.3%. GPs showed considerable variability in screening practices, particularly for individuals who are at no increased risk of colorectal cancer. Mass screening with the faecal occult blood test (FOBT), particularly if it is centrally coordinated, was not widely endorsed, in contrast with strategies which provide a central role for the GP. On the whole, GPs preferred patient-initiated, rather than doctor-initiated, screening. We found a number of knowledge deficits in relation to FOBT screening; many GPs felt they had inadequate training in this area. CONCLUSION: Clear and consistent guidelines for colorectal cancer screening are required. Medical education about colorectal cancer should also be addressed.

Colorectal Neoplasms↗