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Biomedical subjects

J Lawson

Publications and source records attributed to J Lawson.

At least 55 records · Page 3Linked to original sources
PubMed1995

Formation of 8-iso-prostaglandin F2 alpha by human platelets.

F2-isoprostanes are free radical catalyzed prostaglandin F2 isomers formed from arachidonic acid in an enzyme independent manner (1). Analogous families of other prostaglandin isomers have also been described. Detection of these compounds in vivo has been postulated to represent an approach to the quantitative assessment of free radical generation in humans (2). Additionally, the 8-iso analogues of PGF2 alpha and PGE2 have been shown to induce vasoconstriction, a response which is prevented by pharmacological antagonists of the thromboxane receptor (3). Consequently, it is conceivable that these particular isomers might exhibit an autacoidal function. We chose to explore the factors which regulate the biosynthesis of one of these compounds, 8-iso-PGF2 alpha, in vivo and by human platelets in vitro, to understand more clearly how the discovery of these compounds might be exploited to further our understanding of free radical catalyzed processes in vivo.

Adult↗
PubMed1994

Extraocular muscle problems in thyroid eye disease.

In this paper methods of visualisation of the extraocular muscle changes in thyroid eye disease are discussed. The histopathology of extraocular muscle biopsies has been studied by both light and electron microscopy to show the type of cellular infiltration and the amorphous material in the extracellular matrix. A series of questions to which answers have not yet been found concerning thyroid eye disease are posed which may help to direct new research projects. Finally, in the last part of the paper, the surgical results in a series of 41 patients having ocular muscle surgery for diplopia and/or compensatory head postures due to thyroid eye disease are described. The conclusions drawn from these results are that one should maintain the patient euthyroid, establish by orthoptic measurements that the ocular movements have been stable for at least 6 months, treat by recessing tight muscles using adjustable sutures, and aim to undercorrect the vertical deviation at the time of adjustment.

Diplopia↗
PubMed1994

Heart rate and blood pressure responses to carotid sinus massage in healthy elderly subjects.

The purpose of the study was to define heart rate and blood pressure responses to supine and upright carotid sinus massage in healthy elderly subjects and thus to establish the validity of current diagnostic criteria for carotid sinus syndrome in this age group. Twenty-five healthy asymptomatic subjects (61-87 years) had carotid sinus massage carried out following a standardized technique employing previously defined criteria for abnormal heart rate and blood pressure responses: 3 s asystole and a 50 mmHg fall in systolic blood pressure independent of any heart rate slowing (after intravenous atropine). No cardioinhibitory responses of greater than 3 s were documented. The mean maximal cardioinhibitory response was 1038 +/- 195 msec. Right-sided responses were more marked than left when upright (1040 +/- 202 vs. 946 +/- 135 msec; p < 0.01) but not when supine (1094 +/- 215 vs. 1073 +/- 194 msec; NS). After atropine three subjects (12%) had a significant vasodepressor response when upright, but none when supine. The mean maximal vasodepressor response was 21 +/- 14 mmHg. Right-sided blood pressure responses were more marked than left (p < 0.01). There was no fixed relationship between maximum heart rate slowing and the degree of vasodepression during massage (range 2-80 msec/mmHg). The diagnostic criteria for heart rate and blood pressure responses in carotid sinus syndrome are appropriate for supine carotid sinus massage in elderly subjects. Asymptomatic vasodepressor responses occur in a small proportion of healthy elderly when upright.

Aged↗
PubMed1994

Intravenous cannulation alters the specificity of head-up tilt testing for vasovagal syncope in elderly patients.

Prolonged head-up tilt is increasingly used as a diagnostic test for vasovagal syncope. Its sensitivity is reported to increase with the concurrent administration of intravenous isoprenaline. False-positive responses are common in young controls particularly following intravascular instrumentation. We studied the influence of intravenous cannulation alone on responses to head-up tilt in ten healthy elderly subjects. All remained asymptomatic during tilt when non-cannulated whilst five developed symptomatic hypotension following cannulation. Thus, intravascular instrumentation influences responses to held-up tilt in elderly subjects; the significance of positive responses obtained using intravenous isoprenaline in this age group requires further evaluation.

Aged↗
PubMed1994

Incidence of complications after carotid sinus massage in older patients with syncope.

OBJECTIVE: To review the incidence of neurological complications occurring after carotid sinus massage performed for diagnostic purposes. DESIGN: Case review and comparison with previously published work. SETTING: Syncope Clinic, Royal Victoria Infirmary, Newcastle-upon-Tyne, and Chelsea and Westminster Hospital, London. PARTICIPANTS: Patients undergoing investigation of dizziness, syncope, or unexplained falls. METHODS: Carotid sinus massage performed for 5 seconds in both supine and erect postures, both before and after atropine. Contraindications to carotid sinus massage were the presence of carotid bruits, recent myocardial or cerebral ischemia, or previous ventricular tachyarrhythmias. RESULTS: Two cases of neurological complications were reported from a total of 500 patients (2000 massage episodes) investigated in one center, giving an incidence of 0.1%. Combining this data with another center performing investigations in a similar fashion, seven neurological complications arose from a total of 5000 massage episodes, an incidence of 0.14%. Reported complications were pyramidal signs in five cases and visual field defects in two. Pyramidal weakness persisted in one case with a pre-existing stroke on the same side, and a visual field loss was permanent in one. CONCLUSIONS: Neurological complications following carotid sinus massage for diagnosis of the carotid sinus syndrome are uncommon and usually transient. Contraindications to carotid sinus massage should be respected and the standardized technique used.

Aged↗
PubMed1993

New techniques for guiding catheter management during directional coronary atherectomy.

Directional coronary atherectomy (DCA) is an important advance in the mechanical revascularization of stenotic coronary arteries. The bulky nature of the DCA device has necessitated the use of guiding catheter designs that are more cumbersome to use than balloon angioplasty guiding catheters. Because engagement of coronary artery ostia with the currently available DCA guiding catheters is often difficult and because DCA guiding catheters significantly "relax" and reshape during the atherectomy procedure, angiography using these guiding catheters before and after atherectomy can be suboptimal. A new technique for angiography during atherectomy using long Judkin's diagnostic catheters inserted through the existing DCA guiding catheters is described. This technique can be used for optimal visualization of the coronary arteries with minimal use of contrast before and after sessions of atherectomy and also can be used to help engage the DCA guiding catheters. Some improvements in the design of guiding catheters for DCA are suggested.

Atherectomy, Coronary↗
PubMed1993

Clinical characteristics of vasodepressor, cardioinhibitory, and mixed carotid sinus syndrome in the elderly.

PURPOSE: Carotid sinus syndrome (CSS) is frequently overlooked as a cause of syncope in the elderly. It is diagnosed when carotid sinus massage (CSM) produces asystole exceeding 3 seconds (cardioinhibitory CSS), a reduction in systolic blood pressure exceeding 50 mm Hg independent of heart rate slowing (vasodepressor CSS), or a combination of the two (mixed CSS). Most published data pertain to the cardioinhibitory subtype. The recent availability of noninvasive phasic blood pressure monitoring has allowed accurate routine assessment of the vasodepressor response to CSM. The aim of this study was to assess the clinical characteristics of vasodepressor, cardioinhibitory, and mixed CSS. PATIENTS AND METHODS: CSM was carried out on 132 consecutive patients over 65 years referred for investigation of dizziness, falls, or syncope. Massage was performed both supine and upright with continuous electrocardiographic and phasic blood pressure monitoring. Patients exhibiting greater than 1.5-second asystole were given 600 micrograms of intravenous atropine to abolish heart rate slowing and allow assessment of the pure vasodepressor response. RESULTS: Carotid sinus hypersensitivity was documented in 64 patients (mean age 81 +/- 7 years, 31 male). The response was vasodepressor in 37%, cardioinhibitory in 29%, and mixed in 34%. Thirty-six patients had recurrent syncope, 17 presented with unexplained falls, and the remainder had dizziness alone. Symptoms had been present for a median of 24 months, and the median number of syncopal episodes was four. Twenty-five percent had sustained a fracture and, of these, 93% had not experienced a prodrome. Head movement precipitated symptoms in 47% and vagal stimuli in 73%. Episodes were unwitnessed in two thirds of patients. Twelve patients who presented with falls denied syncope but had witnessed loss of consciousness during CSM. Mean cardioinhibition was 5 +/- 2 seconds and mean vasodepression 61 +/- 9 mm Hg. The blood pressure nadir occurred rapidly at 18 +/- 3 seconds after massage, and baseline values were regained at 30 +/- 6 seconds. The clinical characteristics of patients with vasodepressor, cardioinhibitory, and mixed responses were similar. CONCLUSION: CSS is an underdiagnosed cause of dizziness, falls, and syncope in the elderly. The vasodepressor form occurs more frequently than previously reported and has clinical characteristics similar to those of the cardioinhibitory and mixed subtypes. Elderly patients with this condition may deny syncope and present with recurrent unexplained falls. CSM, ideally with noninvasive phasic blood pressure monitoring, should be routinely performed in elderly patients with unexplained bradycardic or hypotensive symptoms.

Accidental Falls↗
PubMed1993

Laparoscopic cholecystectomy in patients aged 65 or older.

Laparoscopic cholecystectomy is replacing open cholecystectomy in the surgical management of gallstone disease in healthy individuals. However, the role of laparoscopic cholecystectomy in patients thought to be at higher risk for surgical morbidity is still being defined. The course of patients aged 65 or greater who underwent attempted and successful laparoscopic cholecystectomies were reviewed. Eleven patients (12%) were converted from laparoscopic to open cholecystectomy. For the 83 patients completing laparoscopic cholecystectomy, the median time of surgery was 115 min and the median length of postoperative stay was 1 day. Two patients required parenteral analgesia longer than 48 h. Seven patients were admitted and monitored postoperatively, although five of these were preoperatively planned. Five patients were readmitted within 30 days. One patient was admitted with a myocardial infarction, one a subphrenic abscess, one an incarcerated hernia, one with pyrexia and leukocytosis (for which no source was identified), and one for an elective urinary tract procedure. Laparoscopic cholecystectomy provides patients aged 65 or older the same benefits of shorter hospital stay and less pain than it provides younger patients. Age alone should not be a contraindication to attempted laparoscopic cholecystectomy.

Age Factors↗
PubMed1993

The costs and experiences of caring for sick and disabled geriatric patients--Australian observations.

The costs and experiences of caring for geriatric patients and the effectiveness of a geriatric assessment team have been reviewed in this study from the New South Wales Central Coast. The findings were: that some clients who are referred for placement in nursing homes and who meet standard criteria for admission can be maintained in the community; the cost to the taxpayer of persons admitted to nursing homes was at least $449 to $776 per week (1991 prices), compared to an average cost of $89 per week to maintain at home those whose original assessment met all the criteria for nursing home placement; assessments of needs of some clients were being conducted by five or more separate agencies which led to increased costs and created distrust and confusion for the client; a key factor in the decision to maintain a client in the community was found to be the availability and motivation of carers. A geriatric assessment team has an essential role in mobilising expert assessment and facilitates access to community-based support services to obviate or delay admissions to nursing homes.

Aged↗
PubMed1993

Rejoinder.

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Catchment Area, Health↗
PubMed1993

Aspiration in acute stroke: a clinical study with videofluoroscopy.

To assess the incidence of lung aspiration in acute stroke, and attempt to identify factors which render such patients at risk of aspiration, consecutive patients admitted to hospital within 24 h of their first symptomatic stroke were studied prospectively. Sixty patients who were conscious, and who did not have any preceding neurological or other cause of dysphagia, were assessed clinically and underwent a bedside water-swallowing test and videofluoroscopy within 72 h of stroke. Twenty-five patients (42%) were seen to aspirate at videofluoroscopy; of these 20% did not have overt dysphagia as detected by a simple water-swallowing test. Factors found to be significantly associated with aspiration were reduced pharyngeal sensation, dysphagia and stroke severity. Aspiration is common in the early period following acute stroke; disordered pharyngeal sensation is an important concomitant of this and should be carefully tested in each patient admitted with acute stroke.

Aged↗
PubMed1993

Comparison of adolescent pregnancy outcomes by prenatal care source.

To determine whether a difference existed in prepregnancy characteristics, pregnancy course and immediate outcomes of pregnant adolescents based on source of prenatal care, we retrospectively reviewed the pregnancies of all adolescents aged < or = 17 years who delivered from 1985 to 1986 at The University of Texas Medical Branch, Galveston. The sample of 1,080 included 660 (61%) teenagers who participated in a teen pregnancy clinic, 277 (26%) teenagers who participated in traditional prenatal care and 143 (13%) who received no prenatal care. Teen clinic participants differed from the other two groups in that they were more likely to be unmarried (P = .02) and to be primagravidae (P = .05). Teenagers receiving care were also of higher gynecologic age than those not receiving care (P = .02). Ethnic distribution, chronologic age, education completed and smoking behavior were similar among the three groups. Although teen clinic participants began prenatal care earlier and had more visits than traditional care participants, both groups had similar pregnancy outcomes. Groups receiving prenatal care had better outcomes (Apgar scores, preterm births, low and very low birth weight) than those who received no care.

Adolescent↗
PubMed1992

Inhibition and inactivation of monoamine oxidase by 3-amino-1-phenyl-prop-1-enes.

We have previously shown that E-3-amino-1-phenyl-prop-1-ene (E-cinnamylamine) is readily oxidised by monoamine oxidase (MAO) type B from either rat or bovine liver (Williams et al. (1988), Biochem. J. 256, 411-415) in each case producing a non-linear progress curve which was attributed to inhibition by the reaction product E-cinnamaldehyde. We have now found that although this aldehyde inhibits MAO B competitively (Ki 0.017 mM) this cannot account for the inhibitory process, since during a 60 min incubation with the substrate (0.5 mM; Km, 0.074 mM) more than 95% inhibition of MAO B was observed and the concentration of aldehyde had reached approx. 0.025 mM. Inhibition was relieved either by dialysis or dilution of inhibited samples. The activity of MAO A from rat liver was largely unaffected by E-cinnamylamine. Oxidation of N-methyl-E-cinnamylamine and its Z-isomer by MAO B produced progress curves similar to that obtained with the primary amine, but in these cases inhibition was not reversed either by dilution or dialysis. Partition ratios for the pair of N-methyl isomers with bovine MAO B were calculated to be 1640 (E-isomer) and 1430 (Z-isomer). The time-dependent inhibition process for all three amines obeyed pseudo-first-order kinetics. A tritiated form of N-methyl-E-cinnamylamine, incubated with MAO B from bovine liver, resulted in incorporation of radioactivity into the enzyme. This labelling was stable to dialysis and to SDS-PAGE.

Acrolein↗
PubMed1992

The Royal Women's Hospital Family Birth Centre: the first 10 years reviewed.

In reviewing the first 10 years experience of the Royal Women's Hospital Family Birth Centre (FBC), we examined the outcomes of pregnancy and labour in a group of women who requested alternative birthing care and who were identified antenatally as being a 'low-risk' population. This study is a retrospective analysis of 5,365 women booked with the birth centre between 1980 and 1989. Over 16% of women developed antenatal complications precluding further care there, while a further 16% developed complications in labour requiring transfer out to conventional labour wards. Thus 67% of those originally booked delivered in the FBC. The instrumental delivery rate was 11%, and the Caesarean section rate was 4%. Of the women who delivered in the FBC, 3.1% had a postpartum haemorrhage and 1.8% required manual removal of placenta. Approximately 4% of babies born in the FBC required some resuscitation, and 0.8% needed admission to the neonatal nursery. Two perinatal deaths occurred in women admitted in labour to the FBC with a live baby, whilst 2 other women presented in labour with a fetal death in utero (perinatal mortality 0.89 per 1,000).

Birthing Centers↗
PubMed1992

The successful development of decentralised health service management: an evaluation of area health services in New South Wales.

Decentralised provision and management of health services has been regarded by many governments as a means of improving the management of hospitals and health services that have become increasingly expensive, complex and fragmented. There has been no known formal evaluation in Australia of the success or otherwise of health services where such decentralised structures have been put in place. Known as 'area health services', decentralised administration of public hospital and health services were first introduced in Sydney, Australia in 1974. The experience has been evaluated. The outcome appears to be successful in terms of rationalisation, co-ordination and equity, but also because the decentralised health authority embraces responsibility for the health of all members of their community and is not confined to patients who attend hospitals and clinics.

Catchment Area, Health↗
PubMed1991

Health policy reform in the People's Republic of China.

With very limited resources, China has developed perhaps the world's largest network of health care services. The health status of its peoples has risen dramatically during the past 40 years. The reasons for these achievements are complex and include an ideology of equity for all citizens, the near universal availability of adequate food, education, housing, jobs, and transport, and the universal availability of accessible and affordable treatment and preventive health services. Despite these achievements China is facing new problems. These include the aging of the population, continued growth of the population leading to ever increasing demands on all sectors of the economy including health services, urban-rural inequalities, low productivity in the health services, lack of legal safeguards for health protection, a continued burden of infectious and endemic diseases, weak infrastructure for prevention and primary health care, and an increasing burden of chronic diseases associated with tobacco smoking and atherosclerotic circulatory diseases and trauma due to traffic accidents and occupational hazards. Decentralized management, financial incentives for health workers, privatization of medical practitioners, health legislation, and changes to health insurance arrangements have been introduced as a means of addressing the issues. The outcomes have been uneven, with little or no improvements in some problems and good progress in others. Changes in the health system appear to be reflecting not only health reform measures but also general economic reforms.

Aged↗