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Biomedical subjects

R Richards

Publications and source records attributed to R Richards.

At least 55 records · Page 3Linked to original sources
PubMed1997

Potential of surface laser scanning to measure facial movement.

Linear and area measurements on the surface contour of the face have been recorded in a variety of chosen facial postures using surface laser scanning techniques on healthy volunteers. Subjects were scanned before and after active and voluntary (against resistance) movements. Quantitative measurements of changes in these lengths and areas were made by computer integration to provide an impression of the changes that accompany facial expression. Lip movements were found to be associated with dimensional changes at all facial locations tested, imposed by the action of the underlying muscles. The system has a potential value for dynamic monitoring of facial movement.

Adult↗
PubMed1997

The effects of oxymetazoline on lysozyme secretion from the human nasal mucosa.

Lysozyme is a protein secreted by nasal submucosal glands. Its secretion is under cholinergic control. It is considered important in nasal defence as it enzymatically hydrolyses peptidoglycan bonds in bacterial cell walls and has specific activity against Gram-positive bacteria in vitro. Oxymetazoline is freely available as a non-prescription nasal decongestant. Some recent work has shown that it has no effect on histamine-induced plasma exudation but little is known about its effects on glandular secretion. The current study is a randomized controlled study that investigates the effect of topical oxymetazoline on the total protein and lysozyme content of nasal fluid. Thirty healthy volunteers were randomized to receive either a normal saline nasal spray (placebo) or an active spray of oxymetazoline, 0.05% (w/v) in saline. NAR was assessed in all subjects using posterior rhinomanometry and nasal lavage before the application of the spray and again 10 min later. The results were analysed using non-parametric statistics. There was a significant decrease in both the lysozyme and total protein content of nasal lavage after application of oxymetazoline when compared with placebo (p < 0.05). A possible mechanism for the observed decease in total protein and lysozyme would be that the vasoconstrictor effects of oxymetazoline also apply to the vessels supplying nasal submucosal glands and that this decrease in blood supply is reflected by a decrease in secretion.

Administration, Intranasal↗
PubMed1996

Immobilization of small molecules on solid matrices: a novel approach to enzyme-linked immunosorbent assay screening for saxitoxin and evaluation of anti-saxitoxin antibodies.

A novel enzyme-linked immunosorbent assay (ELISA) technology was developed for detecting saxitoxin or evaluation of anti-saxitoxin antibodies, which is based on non-covalent immobilization "free' saxitoxin to Maxisorp microtitre plates. The effect of pH on immobilization was studied in media with wide-range buffering capacities (piperazine-glycylglycine and barbiturate buffers). Increasing pH resulted in better responses, although this was mainly due to non-specific interactions. At pH 10.0, however, saxitoxin immobilization was quite effective and specific. The same pattern was found under four different conditions; absence vs presence of bovine serum albumin precoating and absence vs presence of 150 mM NaCl. The best results (high specific response) were achieved with bovine serum albumin precoating in the presence of 150 mM NaCl. The method of choice involved precoating Maxisorp with 5 micrograms/ml albumin followed by addition of 5 microM saxitoxin in 0.01 M piperazine-glycylglycine buffer, pH 10.0. The efficacy of this technology was demonstrated on a polyclonal rabbit anti-saxitoxin antibody and compared with a conventional ELISA of saxitoxin using saxitoxin-bovine serum albumin conjugate as the coating antigen. In the experiments investigating cross-reactivities of various saxitoxin derivatives based on a competitive assay, significantly greater sensitivity was achieved with the novel approach, e.g. 35 pM saxitoxin could be detected (3 x 10(4) times lower concentrations than using the conjugate). The assay works well with mussel tissue homogenates, and because it does not require the use of the covalent saxitoxin-carrier conjugates it offers a simpler alternative to the traditional ELISA for saxitoxin.

Antibodies↗
PubMed1996

Using clinical and functional data for quality improvement in outcomes measurement consortia.

BACKGROUND: Using standardized measures, American Group Practice Association care providers compiled a national database from which patients could be tracked, allowing for epidemiologic comparisons among treatments, sources of care, and results. Within five years, the consortia expanded from 6 to 55 clinics and from a focus on total hip replacement surgery to eight different health conditions. DATA COLLECTION PROCESS: Reflecting areas of significant public concern, high prevalence, high cost, or research needs, both patient- and provider-source data are collected at group practices at standardized intervals: 6 months, 12 months, and annually thereafter. OUTCOMES DATA MANAGEMENT AND REPORTING: A readily adaptable database infrastructure allows data-collection tools to adapt individual questions to changing conditions in the health care environment while maintaining the integrity of the whole structure. Aggregate-level reports complement individual clinics' own internal analysis efforts by providing a context for the interpretation of results. CASE STUDIES: In a total hip replacement consortium (including more than 2,300 patients), early findings have shown that patients do not fully recover from surgery as quickly as they themselves anticipated. In the cataract consortium, data scores on near, distant, day, night, glare, and overall vision scales improve considerably after cataract surgery, giving clinics a new tool to monitor and improve performance. In the asthma consortium, one clinic reevaluated the distribution of peak flow meters and the reasons for their underuse after noting the low number of patients in the clinic that had peak flow meters. LESSONS LEARNED: Provider participation in study design, instrumentation, data analysis, and feedback is important, and physician buy-in and support are critical to the success of any outcomes initiative. Missing data are the greatest limitations of a longitudinal data set and are difficult to collect through follow-up. There is still much to be learned about what functional status and well being measures can show about the relationship between health care services and patient health.

Asthma↗
PubMed1995

Patient satisfaction with information provided at an outpatient clinic for respiratory diseases.

A survey of 374 unselected patients attending the Respiratory Outpatient Department of a teaching hospital revealed that most patients reported receiving information about the treatment of their disease, but only one-quarter received information about its prognosis. Patients reported receiving satisfactory answers to their requests for information on most occasions, and the overall satisfaction rate with information offered was 88.3%. Patients who had attended the clinic on five or more occasions felt that they had received more information on all items compared with those with fewer than five visits, although the increase was statistically significant only for information on treatment. Patients over 75 years of age generally reported less information than younger patients. The great majority (88.4%) of patients preferred verbal information, but 23% also expressed a desire for written information as well. More attention should be paid to the needs of the elderly and to education about the nature and prognosis of disease. Printed material should also be more widely used.

Adult↗
PubMed1995

Apolipoprotein A-I stimulates placental lactogen expression by human trophoblast cells.

Earlier studies from our laboratory indicated that apolipoprotein A-I (Apo A-I) stimulates the acute release of human placental lactogen (hPL) from trophoblast cells in culture. We have now demonstrated that Apo A-I also causes a secondary increase in hPL release, beginning about 6 h after exposure to Apo A-I, that is blocked by cycloheximide and actinomycin D. Apo A-I also stimulated a dose-dependent increase in hPL promoter activity in JAR cells transfected with a 1.1-kilobase (-1078/2) fragment of the hPL3 promoter coupled to a chloramphenicol acetyltransferase (CAT) reporter gene. Maximal stimulation, 5.2-fold above basal levels, occurred at an Apo A-I concentration of 1.5 mg/ml, which is within the physiological concentration of Apo A-I during pregnancy. 37pA, a synthetic amphipathic peptide that mimics the secondary structure of Apo A-I and stimulates the synthesis and release of hPL, also stimulated a dose-dependent increase in CAT activity, with maximal stimulation comparable to that caused by Apo A-I. In addition, Apo A-I stimulated a modest increase in CAT activity in BeWo choriocarcinoma cells, Chinese hamster ovary cells, and HeLa cells. However, the maximal stimulation of hPL promoter activity in the Chinese hamster ovary and HeLa cells (approximately 2.5-fold above basal levels) was less than that in choriocarcinoma cells, suggesting that trophoblast cell nuclear factors may be necessary for maximal expression of the promoter in response to Apo A-I. Taken together, these results indicate that Apo A-I stimulates hPL gene expression, and that DNA elements in the first 1.1 kilobase of the promoter are sufficient for transactivation by Apo A-I.

Animals↗
PubMed1994

Heat exhaustion in The Sun-Herald City to Surf fun run.

OBJECTIVE: To investigate the relationship between motivational factors and physical and biological causes of heat exhaustion in fun run entrants. DESIGN AND SETTING: Case-control study, The Sun-Herald City to Surf fun runs in Sydney in 1991 and 1992. PARTICIPANTS: There were 63,732 race entrants who completed the run and received a finishing time; 79 runners with heat exhaustion and 310 age, sex and performance matched controls were enrolled in the study. MAIN OUTCOME MEASURE: A diagnosis of heat exhaustion was made if a runner collapsed and, when first receiving medical care, had a rectal temperature of 38 degrees C or higher. RESULTS: Two readily identifiable groups of runners were at high risk of heat exhaustion--accomplished non-élite (preferred) runners and runners of good ability (Group A). The attack rate was highest among accomplished non-élite runners, but a combination of a relatively high rate and the large number of entrants in Group A runners accounted for most cases. Four major risk factors for heat exhaustion were identified: motivation to exceed previous performance targets; failure to drink fluids during the run; failure of trained runners to acclimatise for the race by training in the warmer parts of the day; and previous history of heat exhaustion. CONCLUSION: Information from this investigation will enable more effective targeting of educational prevention programs in The Sun-Herald City to Surf fun run and provide baseline data for monitoring the effectiveness of these programs to modify high risk behaviour by participants.

Adolescent↗
PubMed1994

Expression of retinoic acid receptor subtypes and cellular retinoic acid binding protein-II mRNAs during differentiation of human trophoblast cells.

An in vitro model of trophoblast cell differentiation has been used to examine the developmental expression of retinoid receptor mRNAs during the differentiation of human placental cytotrophoblast cells to syncytiotrophoblast cells. The levels of RAR alpha, RAR beta, RXR alpha mRNA increased by 12, 7, and 3 fold, respectively, during trophoblast differentiation, while the levels of RAR gamma mRNA remained relatively constant; and the increase in retinoid receptor mRNA expression preceded the increase in the expression of placental lactogen (hPL), a specific marker of syncytiotrophoblast cells. CRABP-II mRNA levels were lower in cytotrophoblast cells than in syncytiotrophoblast cells. Mobility shift assays demonstrated the appearance of a specific band that bound to a labeled DNA probe containing a retinoic acid responsive element (RARE) that was most intense from nuclear extracts from syncytiotrophoblast cells. These results suggest possible roles for these receptors in the regulation of trophoblast differentiation and hPL gene expression.

Base Sequence↗
PubMed1994

Three-dimensional US of the fetus. Work in progress.

PURPOSE: To develop a system for three-dimensional (3D) ultrasonography (US) that readily interfaces with conventional equipment and to apply this system to fetal imaging. MATERIALS AND METHODS: An acquisition system based on transputer technology records from the video output of standard clinical scanners was interfaced with a position-sensing device, one component of which was attached to the US probe. The method differs from other 3D US methods as any conventional probe may be used, freehand scanning is possible, and no line-of-sight limitations operate. Such scanning was performed of 25 fetuses with gestation ages of 7-30 weeks. RESULTS: Acquisition typically took 3-5 seconds. Acquisition and reconstruction were successful in 17 of 25 cases and were easiest to perform in the first and second trimester. Surface rendering revealed anatomic detail that was not depicted with two-dimensional scanning. CONCLUSION: The technique has the potential for recording complete anatomic studies for review and visualization of detail that is difficult to perceive on conventional US scans.

Female↗
PubMed1994

Bronchospasm induced by intravenous adenosine.

1. Adenosine is well known to cause bronchoconstriction when inhaled, but to date, there has been only one report following the intravenous route. 2. Adenosine caused bronchoconstriction in two patients (the only two with asthma) out of 26 treated with the drug. In one subject the duration of response was much longer than previously reported following inhalation. 3. We suggest that adenosine may aggravate bronchospasm in some asthmatics and alternative treatments for supraventricular tachycardia should be considered in this group.

Adenosine↗
PubMed1994

Three-dimensional computed tomography cholangiography: a new technique for biliary tract imaging.

Knowledge of the segmental anatomy and intersegmental biliary connections is an essential prerequisite to the effective management of patients with complex biliary strictures. Three dimensional (3D) imaging has the ability to demonstrate complex anatomical relationships that are difficult to appreciate on simple non-invasive two dimensional (2D) imaging. Our aim was to develop a technique for accurate, non-invasive 3D computed tomography (CT) cholangiography. Contiguous 4 mm CT sections were obtained through the liver during a dynamic bolus of 200 ml IV contrast. 3D surface reconstructions were then performed, the biliary system was isolated from surrounding hepatic parenchyma using segmentation and contrast threshold algorithms. 14 patients (six females, eight males, median age 68 years (range 48-82)) were studied. 13/14 had malignant biliary obstruction and one had obstruction secondary to a pancreatic pseudocyst. Obstruction was at the liver hilum in eight, the common bile duct in five and the common hepatic duct in one. Four patients had biliary endoprostheses but were symptomatic from inadequate drainage. There was good demonstration of the biliary anatomy, obstructed segments and intersegmental biliary connections in 13/14; irregular biliary dilatation secondary to primary sclerosing cholangitis rendered interpretation difficult in one. 3D cholangiography provided a useful adjunct to other imaging techniques. In particular, in patients with complex hilar strictures it aided implementation of appropriate interventional drainage procedures.

Aged↗
PubMed1993

Phase I pharmacokinetics study of high-dose fotemustine and its metabolite 2-chloroethanol in patients with high-grade gliomas.

The pharmacokinetics of high-dose fotemustine followed by autologous bone-marrow transplantation during a phase I-II clinical trial in 24 patients with glioblastoma or astrocytoma (grade III-IV) was investigated. Plasma levels of fotemustine were determined by high-performance liquid chromatography (HPLC) and UV detection. The metabolite, 2-chloroethanol, was simultaneously followed in six patients by gag liquid chromatography and electron capture detection (GLC-ECD) assay. The drug was given as a 1-h infusion on 2 consecutive days. In all, 40 pharmacokinetic determinations of fotemustine were made at dose levels ranging from 2 x 300 to 2 x 500 mg/m2. Plasma drug elimination was best described by a bi-exponential model, with short distribution and elimination half-lives of 4.15 +/- 2.57 and 28.8 +/- 12.1 min being observed, respectively. No significant difference in half-lives or clearance was seen between the first and the second administration. During dose escalation, the mean area under the concentrationtime curve (AUC) increased from 5.96 +/- 2.89 to 12.22 +/- 3.95 mg l-1 h. Drug clearance was independent of the dose given and equal to 109 +/- 65 l/h, indicating no possible saturation of metabolism and elimination mechanisms at these high-dose levels. The metabolite 2-chloroethanol appeared very early in plasma samples. Its elimination was rapid and rate-limited by the kinetics of the parent compound, giving the same apparent terminal half-life. A close relationship between AUC and C45 values was evidenced (r = 0.890). Associated with the stability of fotemustine kinetic parameters, this could be used in future studies for individual dose adjustment, particularly for high-dose fractionated regimens.

Adult↗
PubMed1993

An evaluation of rapid exchange and simultaneous grip tests.

The usefulness of the rapid exchange grip test and a modification of this test, the rapid simultaneous grip test, in detecting submaximal grip efforts was evaluated. Uninjured subjects giving maximal or submaximal grip efforts were tested at grip rates of 80 and 100 repetitions per minute. Rapid exchange grip at 80 repetitions per minute yielded a sensitivity of 86% and a specificity of 97%. Rapid simultaneous grip at 80 repetitions per minute yielded a sensitivity of 81% and a specificity of 93%. Poorer sensitivities and specificities resulted when a clinical population of patients was tested. Patients who were not giving maximal efforts tended not to comply with the test protocol. The rapid exchange and rapid simultaneous grip tests do assist in detecting submaximal grip efforts; limits to these tests are emphasized.

Adolescent↗
PubMed1993

Need for a comparative performance standard for dry powder inhalers.

The efficacy of dry powder inhalers is dependent on the inspiratory flow rate at which they are used. The resistance to airflow through five different dry powder inhaler devices was measured. The devices were shown to vary significantly, with the Turbohaler having the highest resistance. We suggest that the performance of dry powder inhalers should be assessed at comparable pressure drops producing clinically relevant inspiratory flow rates for each device.

Nebulizers and Vaporizers↗
PubMed1993

Three-dimensional visualization of data on human anatomy: diagnosis and surgical planning.

A system is described which produces displays of anatomical surfaces from sets of X-ray computed tomography (CT), magnetic resonance imaging (MRI) and ultrasonographic scans (US). The displays are created to show the three-dimensional character of the internal and external anatomy. The images may be manipulated on the screen to simulate dissection of the three-dimensional object they represent. Thus it is possible to increase the diagnostic value of the original data and to plan surgery by simulation. To allow long-term studies on the human face for surgical planning and assessment a non-hazardous optical scanning system has been devised. The display system also produces data to drive a numerically controlled milling machine for the production of models, prostheses and implants.

Anthropometry↗