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Biomedical subjects

S Parker

Publications and source records attributed to S Parker.

At least 91 records · Page 5Linked to original sources
PubMed1997

Influence of additives on the water uptake of hydrosilanized silicone rubbers.

Water uptake characteristics of a silicone polymer containing additives of varying solubility have been investigated. A hydrophobic silica, a sparingly soluble agent and a soluble catalyst were added to a stoichiometrically balanced hydrosilanized silicone polymer (the inherent absorption of which was 0.09 wt%). The diffusion coefficients for desorption of all materials were of the order 10(-6) cm2s-1, whereas the diffusion coefficients for absorption showed a decrease with increasing hydrophilicity and solubility of the additive. The greater the solubility of the additive, the more prolonged the uptake and the greater the deviation from classic diffusion theory.

Absorption↗
PubMed1997

Mucosal immunization with DNA-liposome complexes.

The mucosal surfaces represent the primary site for transmission of several viruses including HIV. To prevent mucosal transmission and dissemination to the regional lymph nodes, an effective HIV vaccine may need to stimulate immune responses at the genital and rectal mucosa. Optimal induction of mucosal immunity in general requires targeting antigens to the specialized antigen presenting cells of mucosal associated lymphoid tissues. The nasal mucosa may provide a simple, non-invasive route to deliver DNA encoding the introduced gene to stimulate mucosal immunity. As a first step to evaluate the feasibility of this approach, we have investigated as a model system, systemic and mucosal immune responses elicited to firefly luciferase generated by DNA immunization. Incorporating DNA into liposomes with cationic lipids enhanced luciferase expression in nasal tissue, and was associated with induction of a humoral response in serum and vaginal fluids and also a proliferative and cytotoxic T lymphocyte response in the spleen and iliac lymph nodes draining the genital and rectal mucosa.

AIDS Vaccines↗
PubMed1996

The introduction and auditing of a formal do not resuscitate policy.

AIMS: To introduce, to assess the use of and the staff understanding of a do not resuscitate policy. METHODS: A policy was developed with legal, medical, nursing and ethical input. Two distinct methods for a do not resuscitate order were allowed. The first method is where the patient requests a do not resuscitate order. The second is the medically indicated do not resuscitate order. The policy was trialed on two floors at Dunedin Hospital and an audit performed. Information was collected on patients receiving do not resuscitate orders. The notes of all patients dying on these floors were reviewed. A questionnaire was sent to clinical staff working on the trial floors which included questions on their understanding of issues related to do not resuscitate orders. RESULTS: 86% of deaths had a do not resuscitate order, 26% in accordance with the formal policy. Thirty percent of the time there was no record of a discussion of the do not resuscitate order with the patient or their family. Problems identified by staff included difficulty with raising and discussing these orders with patients and their families. Staff misunderstanding of consent and responsibility for treatment decisions for mentally competent and incompetent patients was common. CONCLUSIONS: There is a need for further staff education and discussion of the issues surrounding do not resuscitate orders. Discussion with patients and their families could be improved.

Adult↗
PubMed1996

Effect of composition on the gelation of tissue conditioners.

Tissue conditioners comprise poly(ethyl methacrylate) powder (or related copolymer) and a liquid containing a plasticizer and ethanol. Gelation times for two butyl/ethyl copolymers and one poly(ethyl methacrylate) polymer with buty phthalyl butyl glycollate or di-2-ethyl hexyl maleate and varying amounts of ethanol have been measured in the range 20-40 degrees C. The proprietary material "Viscogel" was used as a standard. Results were plotted according to the Arrhenius equation enabling activation energies to be determined. Values for activation energies ranged from 55 to 110 KJ mol-1 K-1. The 60/40 butyl/ethyl methacrylate copolymer gave the lowest values and those containing poly(ethyl methacrylate) the highest.

Biocompatible Materials↗
PubMed1996

An epidemiological investigation of Norwalk virus infection in South Africa.

A study was carried out to determine the incidence and seroprevalence of Norwalk virus (NV) in the Pretoria area, South Africa, using a recombinant NV (rNV) immunoassay for the detection of serum IgG antibodies. Maternal antibody was detectable in infants' sera up to approximately 6 months of age. Infection with NV was detected serologically in the second year of life and the seroprevalence of NV IgG rose from 37.1% at 7-11 months of age to 62.1% by the age of 40 years. No significant differences in seroprevalence of NV IgG antibody was evident between subjects of European or African ethnic origin, where overall seroprevalence rates were 56.4% and 53.9% respectively.

Adolescent↗
PubMed1996

The effect of stimulus range on perceived contrast: evidence for contrast gain control.

In audition, loudness matches across frequency are affected by the range of stimuli employed at each frequency (e.g., Marks, 1988; Schneider & Parker, 1990). For example, the loudness of a 500-Hz tone that matches the loudness of a 60-dB 2-kHz tone can be changed by as much as 10 to 20 dB by manipulating the range of intensity values to which the listener is exposed. The goal of the present study was to determine whether stimulus range had a similar effect on the perceived contrast of vertical gratings whose spatial frequencies were either 1 or 4 cycles/deg. Viewers judged the perceived contrasts of 1 and 4 cycle/deg gratings intermixed within a session using the method of magnitude estimation. Four different conditions were created by combining either a set of low-contrast or high contrast gratings at one frequency with a broad range of contrasts at the other frequency. When the broad-range set was at 1 cycle/deg, contrast matches across spatial frequencies were unaffected by changing the range of the 4-cycle/deg gratings from low to high. However, when the broad-range set was at 4 cycles/deg, contrast matches were changed by changing the range of the 1 cycle/deg gratings. This asymmetry in the "range effect" was shown to be consistent with the characteristics of the two channels' receptive-field profiles.

Adult↗
PubMed1996

Home-use nebulizers: a potential primary source of Burkholderia cepacia and other colistin-resistant, gram-negative bacteria in patients with cystic fibrosis.

Inhalation of aerosols contaminated with gram-negative bacteria generated from home-use nebulizers used by cystic fibrosis (CF) patients may be a primary route for bacterial colonization of the lung. Burkholderia cepacia was isolated from 3 of [corrected] 35 home-use nebulizers, and Stenotrophomonas maltophilia was isolated from 4 of 35 home-use nebulizers. Sputum cultures for two patients whose nebulizers were contaminated with B. cepacia did not yield the organism. However, DNA macrorestriction analysis by pulsed-field gel electrophoresis confirmed that one of two strains of B. cepacia recovered from the nebulizer of a third patient was also present in the sputum of that patient. Although Pseudomonas aeruginosa was isolated from 34 patients, none of the nebulizers were positive for the organism. Sixty-nine percent of nebulizers were contaminated, and up to 16 different environmental colistin-resistant, gram-negative species were identified. The heaviest contamination was found beneath the chamber atomizer. A questionnaire survey showed that the majority of patients (28 of 34) were receiving nebulized colistin and/or gentamicin. Patients who followed recommended instructions for good nebulizer hygienic practice and paid particular attention to drying had minimal or no contamination of their nebulizers.

Adult↗
PubMed1996

Streamlining breast disease management.

New technology has been developed for performing percutaneous (non-surgical) breast biopsy and tracking the outcome of breast disease patients. The procedure, mammotomy, takes a biopsy of breast tissue lesions quickly during the same office visit at which the screening mammography discovers an abnormality. Because the procedure is non-invasive, it bypasses the extra time and expense of open surgical biopsies. In conjunction with mammotomy, Breast Cancer Manager (BCM) software is intended to streamline breast care data management. These technologies provide the cornerstone of a comprehensive breast health plan that can streamline patient care across specialties. This plan uses an organ-based, multispecialty coalition of practitioners related to the diagnosis and treatment of breast disease. The BCM software provides a central, complete record of all care given to a patient from the first screening mammogram through surgery and adjuvant therapy. All practitioners will have access to its information and at the same time be able to add to it, making it the repository of patient and practice data for management analysis and outcomes reporting. This article looks at the treatment paradigm of breast disease and details the potential cost savings made possible by mammotomy and the BCM software.

Biopsy, Needle↗
PubMed1996

Visuospatial learning: Ruff Light Trail Learning Test.

The assessment of memory typically includes tests for both audioverbal and visuospatial processing, while measurements of learning have primarily utilized the audioverbal mode. However, there exists no compelling reason why learning should not also be assessed in the visuospatial mode. The Ruff Light Trail Learning Test (RULIT) represents such an option. Normative values utilizing 307 volunteers indicated neither significant gender nor educational differences. However, an age effect for those subjects 55 and older was demonstrated, and our data suggest that the major reason for the inferior learning in this older subgroup was their reduced memory capacities rather than their slowed visuospatial processing. Multiple components including learning curves, error analysis, and delayed recall are presented. Test-retest data also indicate an adequate reliability. The validity was compared to concurrently administered neuropsychological tests, and, finally, the potential for neuropsychological application of this new test is discussed.

Journal Article↗
PubMed1996

Women's experiences of general practitioner management of their vaginal symptoms.

BACKGROUND: Little is known about the management of vaginal symptoms despite their frequency. Most vaginal symptoms in non-menopausal women are managed as thrush, although bacterial vaginosis is commoner. AIM: The aim of this study was to measure the experiences of women attending their general practitioner with vaginal symptoms including self-reporting of symptoms, duration and severity, informal support, over-the-counter remedies, sources of information, gender of doctor, expected and actual vaginal examination, and explanations and knowledge of common vaginal infections. METHOD: A postal questionnaire survey was conducted of 490 patients presenting with vaginal symptoms aged between 18 and 48 years who had attended 10 general practices within the previous 3 months in the East Midlands of England. RESULTS: A total of 85% of patients had suffered a previous episode, with 39% having had three or more infections in the previous year. Overall, 68% consult with each episode, and most consult within 7 days of onset of symptoms (median = 4 days). In all, 68% discussed their symptoms with partners, families or friends, but 32% relied solely on their doctor. Some 33% bought over-the-counter remedies. A total of 65% informed themselves further from encyclopaedias, leaflets and women's magazines, but there was a strong request for more information. Out of those questioned, 75% expected a vaginal examination, whereas 57% had such an examination performed. Most were told their symptoms were caused by thrush (78%), but patients' ideas on causation were varied. Most believed sexual transmission played a role in transmission of symptoms. Women were socially embarrassed by their symptoms, with 46% admitting to having the condition on their minds all or most of the time. Twenty-eight per cent of women wished to see a female doctor, with gender being unimportant to the remainder. CONCLUSIONS: Vaginal symptoms were commonly recurrent, socially embarrassing and managed as candidiasis. Just over half the patients had a vaginal examination. There is a shortage of suitable information on vaginal infections available to patients, many of whom used over-the-counter medications.

Adolescent↗
PubMed1995

p57KIP2, a structurally distinct member of the p21CIP1 Cdk inhibitor family, is a candidate tumor suppressor gene.

Cyclin-dependent kinases (Cdks) are positive regulators of cell proliferation, whereas Cdk inhibitors (CKIs) inhibit proliferation. We describe a new CKI, p57KIP2, which is related to p21CIP1 and p27KIP1. p57KIP2 is a potent, tight-binding inhibitor of several G1 cyclin/Cdk complexes, and its binding is cyclin dependent. Unlike CIP1, KIP2 is not regulated by p53. Overexpression of p57KIP2 arrests cells in G1. p57KIP2 proteins have a complex structure. Mouse p57KIP2 consists of four structurally distinct domains: an amino-terminal Cdk inhibitory domain, a proline-rich domain, an acidic-repeat region, and a carboxy-terminal domain conserved with p27KIP1. Human p57KIP2 appears to have conserved the amino- and carboxy-terminal domains but has replaced the internal regions with sequences containing proline-alanine repeats. In situ hybridization during mouse embryogenesis revealed that KIP2 mRNA displays a striking pattern of expression during development, showing high level expression in skeletal muscle, brain, heart, lungs, and eye. Most of the KIP2-expressing cells are terminally differentiated, suggesting that p57KIP2 is involved in decisions to exit the cell cycle during development and differentiation. Human KIP2 is located at 11p15.5, a region implicated in both sporadic cancers and Beckwith-Wiedemann syndrome, a familial cancer syndrome, marking it as a candidate tumor suppressor. The discovery of a new member of the p21CIP1 inhibitor family with novel structural features and expression patterns suggests a complex role for these proteins in cell cycle control and development.

Amino Acid Sequence↗
PubMed1995

Doppler determined aortic acceleration after dipyridamole in the prediction of coronary artery disease.

Change in the acceleration of aortic blood flow with stress testing is reported to reflect the presence of myocardial ischaemia. We studied its clinical usefulness when compared with dipyridamole thallium scintigraphy in 101 patients, of whom 64 had coronary angiography. Maximum aortic acceleration increased after dipyridamole (P < 0.0001), although no correlation existed between the aortic acceleration and evidence of thallium perfusion abnormalities. For the patients who had angiography, the increase in aortic acceleration was similar for those with no significant coronary stenoses, single vessel or multi-vessel disease. Compared with coronary angiography, Doppler measurement of maximum aortic acceleration had a sensitivity of 92% and a specificity of 37% for the detection of coronary artery disease. When patients with previous myocardial infarction or left ventricular dysfunction were excluded, there was still no relationship between the maximum aortic acceleration and the presence of coronary artery disease. We conclude that changes in the acceleration of aortic blood flow after dipyridamole stressing do not predict the presence or severity of coronary artery disease as measured from perfusion defects at thallium scintigraphy or by coronary angiography. We have observed a wide variability of aortic maximum acceleration in the evaluation of myocardial ischaemia, which we feel introduces serious limitations to its use in routine clinical practice.

Acceleration↗