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Biomedical subjects

P Williams

Publications and source records attributed to P Williams.

At least 361 records · Page 20Linked to original sources
PubMed1991

Case payment: a New South Wales perspective.

This paper addresses the role of casemix systems within the NSW public health system. In NSW, Areas and Regions are funded according to a casemix modified population-based funding formula (Resource Allocation Formula). The RAF is compared with case payment as a means of funding hospitals. It is argued that because of the current shortcomings in casemix funding, including output orientation, inapplicability to ambulatory and non-acute inpatients, and limited scope for global expenditure control, case payment should not be introduced as the mechanism for funding hospitals. However, it is recognised that there is scope to combine population-based funding at area/region level, with case payment to individual agencies.

Attitude to Health↗
PubMed1991

Geographical distribution of the subgenus Helcocyrtomyia, genus Lutzomyia (Diptera: Psychodidae--Phlebotominae).

The known geographical distribution of species included in the subgenus Helcocyrtomyia Barretto is reviewed. It is suggested that the vexator series of the subgenus originated in the Nearctic Region and extended southwards along the Andes (peruensis series) whereas the oswaldoi series is a South American assemblage originating in Gondowana. It is concluded that Helcocyrtomyia cannot be accepted as a monophyletic group.

Americas↗
PubMed1991

Conditions affecting direct gene transfer into rodent muscle in vivo.

This report extends our previous findings that mouse muscle cells in situ can take up naked DNA injected intramuscularly in vivo. Various conditions such as needle type, speed of injection, volume of injection fluid, tonicity of injection fluid, type of solute, type of muscle, physiologic condition of the muscle and age of the animals were appraised for their effect on the levels of luciferase activity expressed from the pRSVL plasmid. Specific conditions such as the use of normal saline as an injection fluid increased the efficiency of expression. The implantation of DNA pellets was an effective way to deliver DNA to muscle, especially for smaller muscle groups. Also, newborn and adult rat muscles expressed plasmid DNA delivered intramuscularly.

Aging↗
PubMed1991

Changes in sex ratio during attempts to establish a laboratory colony of Lutzomyia longipalpis (Diptera: Psychodidae).

After the discovery of "one spot" and "two spot" male Lutzomyia longipalpis in the same dog's kennel, attempts were made to establish laboratory colonies of the two forms. Pure lines of the two forms were not obtained and various "intermediate" males were recorded. Interbreeding between the two populations probably occurs in nature but appears precarious. In one colonization attempt a change in sex ratio was noted from the 7th generation onwards and only females emerged in the 11th generation.

Animals↗
PubMed1991

Direct gene transfer and expression into rat heart in vivo.

We found previously that genes injected into skeletal muscle can be taken up by myofibers and expressed. In the present study we found that myocardial cells can also express a variety of reporter genes injected into myocardium as efficiently as skeletal myofibers, while the cells of several other tissues cannot. The inability of tissues other than striated muscle to express injected DNA is not due to technical difficulties of injection because injected DNA was detected in these other tissues by PCR analysis. These results suggest that skeletal and cardiac muscle cells have unique features such as T tubules that may play a critical role in DNA uptake. Expression in cardiac muscle was stable for only two weeks, possibly because of an immune response against the transfected cells. The ability to directly transfer genes into myocardial cells raises the possibility of gene therapy for both acquired and genetic heart diseases.

Animals↗
PubMed1991

Biodegradable microparticles as controlled release antigen delivery systems.

A model but poor immunogen, ovalbumin (OVA), was entrapped in a novel antigen delivery system comprising poly (D,L-lactide-co-glycolide) (PLGA) microparticles. Both the primary and the secondary IgG antibody responses obtained with OVA in microparticles were compared to those obtained with OVA emulsified in Freunds' adjuvants by two routes of immunization, intraperitoneal (i.p.) and subcutaneous (s.c.) injection. Following single i.p. or s.c. injections, the IgG serum antibody responses to OVA in microparticles were significantly greater than the responses to OVA in Freunds' complete adjuvant (FCA) for up to 10 weeks. After s.c. booster doses of OVA, the secondary IgG antibody responses to OVA in microparticles remained greater than the secondary responses to OVA in Freunds', but not significantly so. Furthermore, the primary IgG responses to OVA in microparticles obtained 8-12 weeks after a single i.p. injection were greater than the secondary responses to OVA in Freunds' obtained by repeat s.c. injections at Weeks 0 and 6. These results demonstrate that microparticles can function as potent antigen delivery systems for an entrapped antigen. Due to their ability to degrade slowly in vivo and to release entrapped antigens, microparticles have considerable potential as controlled release antigen delivery systems for the induction of long-term immune responses.

Animals↗
PubMed1990

Molecular ion imaging and dynamic secondary ion mass spectrometry of organic compounds.

An ion microscope equipped with a resistive anode encoder imaging system has been used to acquire molecular secondary ion images, with lateral resolution on the order of 1 microns, from several quaternary ammonium salts, an amino acid, and a polynuclear aromatic hydrocarbon which were deposited onto copper transmission electron microscope grids. All images were generated by using the secondary ion signal of the parent molecular species. The variation of parent and fragment molecular ion signals with primary ion dose indicates that, for many bulk organic compounds, bombardment-induced fragmentation of parent molecules saturates at primary ion doses of (1-8) X 10(14) ions/cm2. Subsequent ion impacts cause little further accumulation of damage in the sample, and intact parent molecular ions are sputtered even after prolonged ion bombardment (i.e. primary ion doses greater than 1 X 10(16) ions/cm2). This saturation process allows molecular images to be obtained at high primary ion doses and allows depth profiles to be obtained from simple molecular solid/metal test structures.

Mass Spectrometry↗
PubMed1990

Analysis of glycosylation changes in IgG using lectins.

A simple rapid assay based on the ability of lectins to bind carbohydrates has been developed to analyse changes in the oligosaccharide chains of IgG. Bandeiraea simplicifolia lectin and Ricinus communis agglutinin have been used to detect terminal N-acetylglucosamine and galactose moieties respectively in IgG using immunodot-blotting. IgG samples (approximately 1 micrograms) were dot-blotted onto nitrocellulose followed by boiling of the blots to expose the carbohydrate moieties. The blots were then treated with biotinylated lectins followed by either streptavidin-biotin-hydrogen peroxidase conjugate or 125I-labelled streptavidin. The colour was developed using chloronaphthol and the blots read on a densitometer. The labelled blots were cut and read on a gamma counter. The use of a monoclonal antibody to N-acetylglucosamine is also discussed. The results obtained using this method are comparable to those obtained by structural analysis.

Arthritis, Rheumatoid↗
PubMed1990

Influence of lipopolysaccharide chemotype on the interaction between Klebsiella pneumoniae and human polymorphonuclear leucocytes.

A series of isogenic mutants lacking either the O1 (O-:K66) or K66 (O1:K-) antigens or both (O-:K-), some of which had additional defects in their LPS core polysaccharide was used to examine the interaction between polymorphonuclear leucocytes (PMNLs) and K. pneumoniae serotype O1:K66. In the absence of serum complement, only a O-:K- strain with a deep rough LPS chemotype elicited a PMNL-dependent chemiluminescent (CL) response. However, following opsonization of the non-capsulated strains by complement, the largest CL response was to the O1:K- mutant. This mutant also activated and bound more complement C3 than any of the other encapsulated or non-capsulated strains examined. Despite the surface exposure of smooth and rough LPS in the encapsulated parent and mutant strains, the K66 antigen reduced the binding of C3 and prevented PMNL activation. Both anti-LPS and anti-K66 antibodies, however, stimulated a PMNL-dependent CL response to the K66 bearing strains.

Antibodies, Bacterial↗
PubMed1990

Direct gene transfer into mouse muscle in vivo.

RNA and DNA expression vectors containing genes for chloramphenicol acetyltransferase, luciferase, and beta-galactosidase were separately injected into mouse skeletal muscle in vivo. Protein expression was readily detected in all cases, and no special delivery system was required for these effects. The extent of expression from both the RNA and DNA constructs was comparable to that obtained from fibroblasts transfected in vitro under optimal conditions. In situ cytochemical staining for beta-galactosidase activity was localized to muscle cells following injection of the beta-galactosidase DNA vector. After injection of the DNA luciferase expression vector, luciferase activity was present in the muscle for at least 2 months.

Animals↗
PubMed1990

Effect of adenotonsillectomy on nocturnal hypoxaemia, sleep disturbance, and symptoms in snoring children.

61 snoring children selected for adenotonsillectomy, mainly for recurrent tonsillitis, were compared with a matched group of 31 healthy children for symptoms of sleep apnoea, extent of sleep hypoxaemia, and amount of sleep disturbance. The studies were repeated six months postoperatively, and after six months in the healthy children. Preoperatively, 61% of the children had degrees of sleep hypoxaemia above normal and 65% had abnormally disturbed sleep. A questionnaire administered to the parents about their children showed abnormal patterns of answers about sleep problems daytime sleepiness, hyperactivity, aggression, learning difficulties, restless sleep, and odd sleeping positions. After adenotonsillectomy, the abnormal hypoxaemia, excessive sleep disturbance, and multiple symptoms almost resolved; a growth spurt also occurred.

Adenoidectomy↗
PubMed1990

Mental health and medical consultation in primary care settings.

This paper examines the effect of psychiatric morbidity, as measured by the GHQ-60, on the probability of being in contact with a primary care physician, and the socio-demographic factors which influenced this effect. We found that the presence of psychiatric morbidity emerged as a major determinant of primary care utilization in both sexes, and about one-sixth of consultations in men and one-fifth of consultations in women could be attributed to it. Logistic modelling was used to investigate the joint effect on general practitioner consultation of psychiatric morbidity and seven socio-demographic variables. Sex, age, and psychiatric morbidity exerted independent, but not interactive, effects on consultation.

Adolescent↗