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Biomedical subjects

J Lawson

Publications and source records attributed to J Lawson.

At least 19 recordsLinked to original sources
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↗
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↗
PubMed1989

Subarachnoid cyst with hydrocephalus--a complication of mid-trimester amniocentesis.

We report a child with a subarachnoid cyst with hydrocephalus following a mid-trimester amniocentesis. Although fetal trauma is a rare complication, it is important to stress the need to perform amniocentesis under ultrasound control. Children with neurological disease or convulsions of unknown origin in early infancy who are born to mothers who have had mid-trimester amniocentesis should have a CT scan as part of the investigations to exclude this rare but nevertheless important complication.

Adult↗
PubMed1989

Use of the Functional Assessment Inventory to distinguish among the rural elderly in five service settings.

This replication study further supports the hypothesis that the Functional Assessment Inventory (FAI) can reliably distinguish between the elderly in different service settings. The five settings studied include a state mental health facility, a nursing home, a visiting nurse service, a senior center, and a control group of well elderly. The inclusion of the home care and control groups in this study provide new tests of the applicability of the FAI. The sample consisted of 125 elderly individuals with 25 subjects in each of the five groups. The FAI questionnaire was administered to the subjects and/or an informant when necessary. Results of a multivariate analysis of variance (MANOVA) revealed that the more functionally impaired individuals were utilizing the more care-intensive settings. The FAI identified three distinct "cluster groups": an institutional cluster (state mental health facility and nursing home), a home care cluster (visiting nurse service), and a community cluster (senior center and control group). Analysis of the subscale scores reveals discrete differences between each of the groups. Implications of the study findings are discussed.

Activities of Daily Living↗
PubMed1989

Is padding necessary after cataract extraction?

The results of a prospective study to assess the value of padding eyes following cataract surgery are reported. A group of eyes dressed with a petroleum jelly mesh, gauze pad, and cartella shield were compared with a group dressed only with a cartella shield. Study of the eyes and lids before and after operation, including the taking of lid margin and fornix swabs for culture, suggested that there was no significant difference in the bacterial presence between the two groups. The eyes dressed with a cartella shield alone appeared less prone to discharge. The relative merits of different types of dressing are discussed.

Bandages↗
PubMed1988

Oxidation of 3-amino-1-phenylprop-1-enes by monoamine oxidase and their use in a continuous assay of the enzyme.

3-Amino-1-phenylprop-1-ene (cinnamylamine) and some derivatives were examined as substrates for monoamine oxidases A and B in mitochondria. All of the amines examined were readily oxidized by monoamine oxidase B but much less readily by monoamine oxidase A. E-Cinnamylamine was found to have Km 0.025 mM and Vmax. 3.9 nmol/min per mg of mitochondrial protein. Corresponding values with monoamine oxidase A were 0.026 mM and 0.85 nmol/min per mg respectively. Despite their different stereochemistry, E- and Z-N-methylcinnamylamines were almost equally effective as substrates for monoamine oxidase B. The characteristic u.v. absorbance and high absorption coefficient of cinnamaldehyde, the product produced by enzymic oxidation of cinnamylamine, is utilized in a sensitive continuous spectrophotometric assay for both enzymes in the rat and for the assay of a purified monoamine oxidase B from bovine liver.

Animals↗
PubMed1988

Effects of low-dose aspirin on endogenous eicosanoid formation in normal and atherosclerotic men.

We have investigated the effects of a low-dose aspirin regimen (120 mg orally, then 20 mg twice daily) on the in vivo synthesis of prostacyclin, thromboxane and prostaglandin E in man by measurement of their urinary metabolites (PGI2-M, TxB2-M, PGE-M) using gas chromatography-mass spectrometry. A comparison was made between the selectivity of low-dose aspirin for thromboxane vs prostacyclin synthesis in patients with atherosclerosis, age-matched controls without vascular disease, and young healthy volunteers. After one week of treatment, aspirin reduced TxB2-M synthesis to a similar extent in the three groups (mean declines of 86, 84 and 78% respectively), while there was an unexpected difference in effect on PGI2-M, with only a 27% fall in the young volunteers but 53% and 54% declines in the patients with vascular disease and their age-matched controls. Serum TxB2 was reduced greater than 98% in all groups while PGE-M excretion was unchanged. These results indicate that bioselectivity for inhibition of Tx synthesis by aspirin is more difficult to achieve in older subjects than in the young volunteers previously studied and that very low, frequent dosing, or a sustained-release preparation of aspirin would be needed to achieve bioselectivity for Tx inhibition in patients with vascular disease.

Adult↗
PubMed1988

Endotoxins in portal blood.

Endotoxemia may complicate diseases of the bowel and liver, and is associated with the occurrence of renal failure, coagulation disorders and death. The bowel contains a large quantity of endotoxins. According to the classical hypothesis, endotoxins continuously transmigrate through the bowel mucosa, thereby entering the portal circulation. However, previous studies on portal endotoxemia were contradictory. We studied the presence of endotoxins in the portal vein in 21 consecutive patients with no diseases of the liver or the bowel, using a sensitive chromogenic endotoxin assay. In only two patients was low level portal endotoxemia detected after cross-clamping of the aorta, and subsequent reperfusion. We conclude that the normal bowel mucosa is an efficient barrier for endotoxins. Therefore, intestinal endotoxemia complicating liver disease is likely to result from enhanced permeability of the bowel mucosa.

Aorta, Abdominal↗
PubMed1987

Blood types of the native Americans of Oklahoma.

Large numbers of Indians from Oklahoma were screened for a variety of red cell antigens. Sufficient numbers of Cherokees, Creeks, and Choctaws were studied to calculate gene frequencies. These tribes originated in the Southeastern United States and were forcibly moved to Oklahoma. The Creeks and Choctaws have not been studied previously. A small number of Cherokees remained in North Carolina, and their blood types have been reported. The blood types of the Oklahoma Cherokees are quite similar to those observed there but one important difference was discovered. The data previously reported concerning the Eastern Cherokees revealed the absence of the Dia antigen. The present study found that the Oklahoma Cherokees do have the Dia antigen, although in a lower percentage than the other southeastern tribes. The Creeks and Choctaws share a linguistic heritage as well as having similar red cell phenotypes.

Blood Group Antigens↗
PubMed1986

Immunoturbidimetric assay of transferrin: effect of iron and need for serum blanks.

The introduction of specific antisera has led to the replacement of total iron binding capacity assays with direct immunochemical measures of transferrin. However, some controversy exists over the effect of the degree of iron saturation on antigen-antibody interactions in these immunochemical assays. This study describes a simple automated immunoturbidimetric assay of transferrin, and includes a reference range and an evaluation of the effects of common potential interferents, including iron, bilirubin, lipemia, and hemoglobin. The measured and the calculated TIBC are also compared for 78 healthy individuals and 51 patients with anemia.

Antigen-Antibody Complex↗