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Biomedical subjects

D Waldron

Publications and source records attributed to D Waldron.

At least 19 recordsLinked to original sources
PubMed2006

Development of polymer-based sensors for integration into a wireless data acquisition system suitable for monitoring environmental and physiological processes.

In this work, the pressure sensing properties of polyethylene (PE) and polyvinylidene fluoride (PVDF) polymer films were evaluated by integrating them with a wireless data acquisition system. Each device was connected to an integrated interface circuit, which includes a capacitance to frequency converter (C/F) and an internal voltage regulator to suppress supply voltage fluctuations on the transponder side. The system was tested under hydrostatic pressures ranging from 0 to 17 kPa. Results show PE to be the more sensitive to pressure changes, indicating that it is useful for the accurate measurement of pressure over a small range. On the other hand PVDF devices could be used for measurement over a wider range and should be considered due to the low hysteresis and good repeatability displayed during testing. It is thought that this arrangement could form the basis of a cost-effective wireless monitoring system for the evaluation of environmental or physiological processes.

Environmental Monitoring↗
PubMed2006

A review of digestible microsystems for gastrointestinal tract diagnostic applications.

Present methods for investigation of the GI tract are invasive, distressing for the patient, and give a low diagnostic yield. Wireless, radio telemetry capsules, capable of monitoring physiological changes or visualizing the GI tract are noninvasive and could realize a faster time to diagnoses along with improved treatment of both organic diseases and functional disorders. Consequently, the patient's quality of life would improve. In this paper, early radiotelemetry capsules and the motivating factors for their development are discussed. Following this, prototype and commercially available digestible microsystems making use of microelectronics and microelectromechanical systems are presented. It is shown that these capsules have the potential to combine the functions of their predecessors and furthermore can be used for visualizing the gastrointestinal tract. These systems have the potential to improve diagnostic yield and, in the future, treatment of disease using these capsules should become a reality.

Capsules↗
PubMed2005

Review of the potential of a wireless MEMS and TFT microsystems for the measurement of pressure in the GI tract.

Telemetry capsules have existed since the 1950s and were used to measure temperature, pH or pressure inside the gastrointestinal (GI) tract. It was hoped that these capsules would replace invasive techniques in the diagnosis of function disorders in the GI tract. However, problems such as signal loss and uncertainty of the pills position limited their use in a clinical setting. In this paper, a review of the capabilities of MicroElectroMechanical Systems (MEMS) and thick film technology (TFT) for the fabrication of a wireless pressure sensing microsystem is presented. The circuit requirements and methods of data transfer are examined. The available fabrication methods for MEMS sensors are also discussed and examples of wireless sensors are given. Finally the limitations of each technology are examined.

Animals↗
PubMed2003

Prospective vs retrospective assessment of lower urinary tract symptoms in patients with advanced prostate cancer: the effect of 'response shift'.

OBJECTIVE: To compare prospectively obtained symptom scores (pre-tests) with retrospective assessment (then-tests) in patients with newly diagnosed advanced prostate cancer. PATIENTS AND METHODS: Patients with newly diagnosed locally advanced or metastatic prostate cancer were recruited. They completed the International Prostate Symptom Score (IPSS) and Symptom Problem Index (SPI) before starting treatment. At 3 and 6 months after diagnosis they again completed these questionnaires, but also retrospectively reassessed their initial symptom level. Healthy age-matched controls were recruited from primary care and completed the same questionnaires; in all, 76 patients and 17 controls participated. RESULTS: The IPSS and SPI scores decreased significantly over the 6 months of the study. Patients retrospectively rated their level of symptoms and symptom bother as higher than their contemporaneous assessments. This was not the case in the control group. CONCLUSION: These results question the assumption that contemporaneously collected pre-test scores are interchangeable with retrospectively assessed then-tests. This suggests that caution is required when comparing the results of studies that use these two alternative techniques of data collection. The difference between then-test and pre-test scores may represent an example of a phenomenon termed 'response shift', in which, by adapting to their disease, patients changed the internal standards by which they assessed their symptoms.

Aged↗
PubMed2003

Severe persistent orf in young goats.

Orf (contagious ecthyma) is a viral disease of small and wild ruminants, humans, and less frequently other species. In sheep and goats, the disease is characterized by the formation of vesiculo-proliferative lesions in the skin of lips and nostril. Here, a form of generalized orf in 16 goat kids from 2 different locations in west Texas is described. The disease was characterized by multifocal, severe, proliferative dermatitis that persisted from about 2 months of age until the goat kids were euthanized 3 months later. All affected goats were Boer or Boer crosses under 1 year of age. The mean immunoglobulin concentration in sera of affected goats was elevated compared with healthy control goats. Severe to moderate lymphadenomegaly of the nodes draining the areas of the skin affected with orf lesions was present in all 16 goat kids. Suppurative arthritis, chronic fibrinous pneumonia, and premature thymic involution were found in 3, 5, and 7 of the goat kids, respectively. The skin lesions of 3 goat kids were infested with larvae of the opportunistic black garbage fly (Ophira sp.). The orf virus was identified in skin lesions by isolation in Marbin-Darby ovine kidney cells, electron microscopy, and amplification of viral DNA by polymerase chain reaction. The orf virus was not detected in peripheral blood or lymph node mononuclear cells of any of the goats. Cross-neutralization experiments showed that an ovine orf virus antiserum raised in sheep was more effective in neutralizing a sheep orf virus isolate than a caprine orf virus isolate. The clinical and epidemiological characteristics of these orf cases may be the result of susceptibility factors within some individuals of the Boer breed of goats.

Animals↗
PubMed2000

Impaired gamma interferon responses against parvovirus B19 by recently infected children.

Parvovirus B19 is the causative agent of "fifth disease" of childhood. It has been implicated in a variety of conditions, including unsuccessful pregnancy and rheumatoid arthritis, and is a potential contaminant of blood products. There has been little study of immunity to parvovirus B19, and the exact nature of the protective humoral and cell-mediated immune response is unclear. Immune responses to purified virus capsid proteins, VP1 and VP2, were examined from a cohort of recently infected children and compared with responses from long-term convalescent volunteers. The results demonstrate that antibody reactivity is primarily maintained against conformational epitopes in VP1 and VP2. The unique region of VP1 appears to be a major target for cell-mediated immune responses, particularly in recently infected individuals. We confirm that antibody reactivity against linear epitopes of VP2 is lost shortly after infection but find no evidence of the proposed phenotypic switch in either the subclass of parvovirus B19-specific antibody or the pattern of cytokine production by antigen-specific T cells. The dominant subclass of specific antibody detected from both children and adults was immunoglobulin G1. No evidence was found for interleukin 4 (IL-4) or IL-5 production by isolated lymphocytes from children or adults. In contrast, lymphocytes from convalescent adults produced a typical type 1 response associated with high levels of IL-2 and gamma interferon (IFN-gamma). However, we observed a significant (P<0.001) deficit in the production of IFN-gamma in response to VP1 or VP2 from lymphocytes isolated from children. Taken together, these results imply that future parvovirus B19 vaccines designed for children will require the use of conformationally preserved capsid proteins incorporating Th1 driving adjuvants. Furthermore, these data suggest novel mechanisms whereby parvovirus B19 infection may contribute to rheumatoid arthritis and unsuccessful pregnancy.

Adult↗
PubMed1999

Quality-of-life measurement in advanced cancer: assessing the individual.

PURPOSE: Despite the increasing importance of assessing quality of life (QoL) in patients with advanced cancer, relatively little is known about individual patient's perceptions of the issues contributing to their QoL. The Schedule for the Evaluation of Individual Quality of Life (SEIQoL) and the shorter SEIQoL-Direct Weighting (SEIQoL-DW) assess individualized QoL using a semistructured interview technique. Here we report findings from the first administration of the SEIQoL and SEIQoL-DW to patients with advanced incurable cancer. PATIENTS AND METHODS: QoL was assessed on a single occasion using the SEIQoL and SEIQoL-DW in 80 patients with advanced incurable cancer. RESULTS: All patients were able to complete the SEIQoL-DW, and 78% completed the SEIQoL. Of a possible score of 100, the median QoL global score was as follows: SEIQoL, 61 (range, 24 to 94); SEIQoL-DW, 60.5 (range, 6 to 95). Psychometric data for SEIQoL indicated very high levels of internal consistency (median r =.90) and internal validity (median R(2) = 0.88). Patients' judgments of their QoL were unique to the individual. Family concerns were almost universally rated as more important than health, the difference being significant when measured using the SEIQoL-DW (P =.002). CONCLUSION: Patients with advanced incurable cancer were very good judges of their QoL, and many patients rated their QoL as good. Judgments were highly individual, with very high levels of consistency and validity. The primacy given to health in many QoL questionnaires may be questioned in this population. The implications of these findings are discussed with regard to clinical assessment and advance directives.

Adult↗
PubMed1997

Quality of life issues in palliative medicine.

The assessment of patient's quality of life is assuming increasing importance in medicine and health care. Illnesses, diseases and their treatments can have significant impacts on such areas of functioning as mobility, mood, life satisfaction, sexuality, cognition, and ability to fulfil occupational, social and family roles. The emerging quality of life construct may be viewed as a paradigm shift in outcome measurement since it shifts the focus of attention from symptoms to functioning. This holistic approach more clearly establishes the patient as the centre of attention and subsumes many of the traditional measures of outcome. Quality of life assessment is particularly relevant to patients with progressive conditions, particularly in the later phases of the disease. Despite the fact that current definitions of palliative medicine include quality of life as a central concern, relatively little research has been conducted on the impact of palliative care on patient quality of life. This paper introduces the concept of quality of life and describes the significant difficulties in definition, measurement and interpretation that must be addressed before such measures can be used as reliable and valid indicators of disease impact and treatment outcomes. It is argued that the unique individual perspective of the patient on his or her own quality of life must be incorporated into outcome assessments aimed at improving the quality of health care delivery in progressive diseases.

Attitude to Death↗
PubMed1994

Anorectal functional deficit in the Brown Bowel syndrome.

The Brown Bowel Syndrome is characterised by degeneration and pigmentation of large bowel mucosa. We present a report of this unusual syndrome in which, for the first time, a functional deficit, reflected in a reduced internal and sphincter tone, is documented. This abnormality was reversed following sub-total colectomy and vitamin E therapy.

Anal Canal↗
PubMed1992

Detection of subclinical autonomic neuropathy in constipated patients using a sweat test.

Chronic idiopathic constipation may be the result of an autonomic neuropathy. This hypothesis was tested in 23 constipated patients and 17 age matched controls, using the acetylcholine sweat spot test devised to test autonomic integrity in diabetes. Acetylcholine (0.01%) was injected in the dorsum of the foot painted with a mixture of starch and iodine. Active sweat glands appeared on the surface of the skin as small black dots which were photographed and counted, using a grid with 60 subareas. Two measurements were made: the number of dots per unit subarea (sweat spot test score) and the % number of abnormal subareas (with less than six spots). These two parameters were correlated. The median sweat spot test score was 9.53 in patients and 13.92 in controls (p = 0.0001), the receiver operating characteristic curve showing that a score of 12 delimited normal and abnormal subjects. Increasing age was correlated with a low score in patients, probably because of prolonged symptoms. Seventy per cent of patients and one control had a borderline or abnormal number of subareas. These results suggest that idiopathic constipation is associated with a degree of autonomic denervation. The sweat spot test is an easy, inexpensive method to test this hypothesis and deserves a place in the clinical assessment of slow transit constipated patients.

Acetylcholine↗
PubMed1992

Duodenal rupture with avulsion of the bile duct: an unusual injury.

Blunt abdominal trauma may give rise to infrequent and unusual patterns of organ damage requiring prompt and complete exploratory laparotomy if the full extent of injury is to be recognised. We present a case of avulsion of the common bile duct in association with duodenal rupture to illustrate the importance of this strategy.

Abdominal Injuries↗
PubMed1991

The role of aspiration cytologic examination in the diagnosis of carcinoma of the breast.

A study of 2,000 patients who had undergone fine needle aspiration of a solid lump of the breast was conducted to determine the accuracy of this technique. During the period 1982 to 1989, all patients with a solid mammary mass, presenting to a specialized breast unit were initially investigated by fine needle aspiration cytologic examination (FNAC). To date, we present data on 2,000 consecutive aspirations with matching histologic diagnosis on the excised pathologic specimens. In particular, the relationship between tumor histologic factors and the accuracy of cytologic diagnosis was examined. The sensitivity of FNAC in the diagnosis of a malignant growth was 84 per cent; this represents first aspiration results only. The specificity was more than 99 per cent. The rate of acellular or unsatisfactory aspirations was 12 per cent. We had a positive predictive rate for diagnosis in carcinoma of the breast of almost 95 per cent. The diagnosis of lobular and in situ patterns of disease was questioned, with three of three in situ lesions and ten of 23 lobular lesions missed by FNAC. We do not recommend that FNAC replace excision biopsy and frozen section in the diagnosis of carcinoma of the breast.

Biopsy, Needle↗
PubMed1990

Prolonged anorectal manometry and external anal sphincter electromyography in ambulant human subjects.

We have developed a method for prolonged combined anorectal manometry and electromyography (EMG) of the external anal sphincter in ambulant subjects. Fourteen healthy volunteers were studied for a total of 284 hr (mean of 20.3 hr/subject). Anorectal manometry was performed using a probe with twin pressure sensors. EMG was recorded by one indifferent and two differential silver-silver chloride surface electrodes positioned 0.5-0.75 cm from the anus on either side. The sampling reflex occurred frequently and was significantly (P less than 0.001) more common during wakefulness than during sleep and also following meals than during fasting (P less than 0.01). The passage of flatus was associated with transient relaxation of the anal canal in 19% of episodes. In contrast, there was a contractile episode with no preceding relaxation in 75% of episodes. The anal sphincter had significantly (P less than 0.05) more action potentials (APs) during the day (12.8 +/- 3.2 APs/10 min) than at night (1.6 +/- 1.3 APs/10 min). During micturition, anal canal pressure rose (mean 15 mm Hg) in association with powerful external anal sphincter contractions. Our data show that, normally, contractile activity both in the anal canal and external anal sphincter maintains fecal continence during micturition and the passage of flatus. The technique should lead to a better understanding of the normal mechanisms of fecal continence during waking and sleep and of the pathophysiology of disorders of anorectal function.

Action Potentials↗
PubMed1990

Retrotracheal goiter: a diagnostic and therapeutic problem.

A patient with chronic cough and recent dysphagia was found to have a retrotracheal mass extending into the visceral mediastinum on chest roentgenogram. A computed tomographic scan confirmed a retrotracheal lesion, which was believed to be of lymphatic origin. A thyroid scan demonstrated downward displacement of the left lobe but little uptake in the mass. Histological findings of mediastinal biopsies were inconclusive. A large retrotracheal thyroid adenoma was easily excised through a right thoracotomy. The approach to diagnosis and, in cases of doubt, the safety of surgical access through thoracotomy for thyroid lesions in this unusual site is discussed.

Adenoma↗
PubMed1990

Distal oesophageal ph monitoring for gastro-oesophageal reflux.

We investigated eight hour distal intra-oesophageal ph testing to see if this could replace the traditional 24 hour test period without significant loss of sensitivity in the diagnosis of gastro-oesophageal reflux (GOR) disease in symptomatic refluxers. Thirty-four patients were tested, all of whom had classical De Meester symptoms of GOR. All patients were admitted to hospital and commenced on 24 hour ambulant ph monitoring of the distal oesophagus. This was followed by a period of eight hour testing. The following variables were determined: (i) total reflux time, (ii) number of reflux episodes (total, upright and supine), (iii) longest episode of reflux, (iv) percent of time that ph was below four (total, upright and supine). All patients underwent endoscopic examination of the oesophagus subsequently. Twenty four hour monitoring resulted in a positive diagnosis of GOR in 26 of 34 patients, giving an overall sensitivity of 75%. Eight hour testing was positive in 23 patients (sensitivity of 68%, not significantly different). The best correlations were obtained when comparing total reflux episodes (r = 0.75, p less than 0.001), and the percent time ph less than 4 (total) (r = 0.69, p less than 0.001). Nineteen patients had evidence of oesophagitis on endoscopy, and in all such patients both eight and 24 hour testing were positive. We conclude therefore, that eight hour ph monitoring can be reliably used in the diagnosis of pathological GOR in patients symptomatic for acid reflux.

Esophagitis↗
PubMed1989

The influence of adaptive seating devices on vocalization.

This study examined the relationship between receipt of adaptive seating devices (ASD) and sophistication of early vocalizations/verbalizations. Eight nonverbal children with cerebral palsy were studied prior to and following receipt of an ASD. Total speech tokens increased for 7 of the 8 subjects and diversity of speech sounds increased for 6 subjects. A concomitant improvement in feeding independence was observed for those subjects who demonstrated the greatest increase in speech sound diversity.

Cerebral Palsy↗