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Biomedical subjects

S Thomas

Publications and source records attributed to S Thomas.

At least 487 records · Page 27Linked to original sources
PubMed1994

Perfluorocarbon distribution to liver, lung and spleen of emulsions of perfluorotributylamine (FTBA) in pigs and rats and perfluorooctyl bromide (PFOB) in rats and dogs by 19F NMR spectroscopy.

Perfluorocarbon emulsion (FCE) particles are reported to be taken up by the reticuloendothelial system (RES) and ultimately eliminated by the lung. This distribution provides an opportunity to measure oxygen partial pressure in vivo with fluorine-19 magnetic resonance imaging (19F MRI). Since the MR image signal-to-noise ratio is directly proportional to the fluorine concentration in the tissue, a greater concentration of perfluorocarbon (PFC) in the tissue will result in a greater confidence in the oxygen image and reduce measurement time. It was postulated that the biodistribution of PFC administered in emulsion form may depend on species RES or FCE composition. The distribution of an emulsion (Oxypherol-E.T.) containing perfluorotributylamine (FTBA) 5 days after administration to pigs (11 g FTBA/kg body weight i.p.) and rats (19 g FTBA/kg i.p.) and an emulsion (Oxygent) containing perfluorooctyl bromide (PFOB) 7 days after administration to dogs (11 g PFOB/kg i.v.) and 5 days after administrations to rats (19 g PFOB/kg i.p.) was analyzed by F-19 NMR spectroscopy of tissue samples. PFC concentrations in spleen are 2 to 3 times those in liver. This pattern appears to be independent of PFC emulsion or species. In contrast, lung PFC content was less than that in the liver and showed a dependence upon both species and PFC emulsion.

Animals↗
PubMed1994

Computerization of clinical laboratories and health care facilities: Making decisions in transition. Part I: General considerations.

In summary, it is perhaps appropriate to reflect on the transition zone that health care finds itself in now. Federally and provincially funded Royal Commission reports and health surveys over the last thirty years have all drawn a number of similar conclusions. Some of these are particularly important to keep in mind as major investments in hospital and laboratory information systems are made. First, it is known that health care providers and services are not distributed evenly throughout the country and that there is uneven utilization of services. Second, the "health" in health care is not defined in purely medical terms. Health is a function of genetic background, personal choices and behaviors like diet and exercise, socioeconomic conditions like housing, family situations, education, and employment, and the physical environment in which an individual lives and works. Governments at all levels now use this concept of health when determining policy and funding. Third, a change of emphasis has occurred from the traditional hospital-centered model to one that is community based. How well will your laboratory and facility responding to the inevitable changes to funding and consumer utilization? How well does the HIS/LIS vendor understand the circumstances affecting your organization and what agreements can be made to ensure future system support? How will an increase in profile-type testing and reflexive testing be handled to minimize disruptions to work flow and productivity? How can analytical instrument selection change the whole focus of the laboratory operation and impact on other areas? Will the traditional terms "in patient" and "out patient" still apply, or will a term somewhere in the middle evolve?(ABSTRACT TRUNCATED AT 250 WORDS)

Canada↗
PubMed1994

A disability perspective on home care.

As the disabled community continues to find its voice, advocates are trying to change the way our society defines disabled persons and the way our health care system defines the services they need. Home- and community-based care can offer the disabled the independence and community access they want--home care agencies should be aware of the special needs of this growing population.

Caregivers↗
PubMed1994

Pattern of caries experience among an elderly population in south India.

A study was carried out among a population aged 60 years or over in South India. The caries experience, as expressed by the DMFT index, was found to be a mean of 13.51, of which the 'missing' component was 10.98. The sample population had an average of 18.42 teeth present but not one of the 300 individuals interviewed and examined had a tooth filled. Details are given of the teeth most commonly carious and missing. Data are also provided on habits and oral hygiene measures and their effect on the oral health of the elderly in this region.

Age Factors↗
PubMed1994

Refractive errors in preterm babies.

Fifty preterm neonates were followed up at the age of 6 months and 1 year. In addition to developmental assessment, a complete ophthalmological examination was done on both visits. The largest (62%) gestational age group was of 34-36 weeks. At 6 months, none of the infants had normal vision. At 1 year of age, 64% of the babies had normal vision while incidence of myopia and hypermetropia was 16% and 20%, respectively. There was an inverse relationship noted between gestation and incidence of refractive errors. It was also noted that with decreasing weight, the incidence of myopia increased. Myopia was seen exclusively among infants of birth weight of 2000 g or less. Birth weight had a significant positive correlation with astigmatism. No correlation of asphyxia with refractive errors was observed. It is recommended that all preterm babies should have an ophthalmological examination at one year of age with follow up later on.

Anisometropia↗
PubMed1994

Evidence of linkage disequilibrium in the Spanish polycystic kidney disease I population.

Forty-one Spanish families with polycystic kidney disease 1 (PKD1) were studied for evidence of linkage disequilibrium between the disease locus and six closely linked markers. Four of these loci--three highly polymorphic microsatellites (SM6, CW3, and CW2) and an RFLP marker (BLu24)--are described for the first time in this report. Overall the results reveal many different haplotypes on the disease-carrying chromosome, suggesting a variety of independent PKD1 mutations. However, linkage disequilibrium was found between BLu24 and PKD1, and this was corroborated by haplotype analysis including the microsatellite polymorphisms. From this analysis a group of closely related haplotypes, consisting of four markers, was found on 40% of PKD1 chromosomes, although markers flanking this homogeneous region showed greater variability. This study has highlighted an interesting subpopulation of Spanish PKD1 chromosomes, many of which have a common origin, that may be useful for localizing the PKD1 locus more precisely.

Alleles↗
PubMed1994

Reaction of 14C-acetaldehyde with whole blood in vitro: further evidence for the formation of unstable complexes with plasma proteins and red cells.

When heparinised whole blood was incubated with 5, 10, 45 or 180 microM 14C-acetaldehyde for 1 hr, an average of 33%, 34%, 33% and 41%, respectively, of the radioactivity was associated with red cells and the remainder with plasma. Although 71-80% of the radioactivity in the plasma was TCA-precipitable, only 0.9-3.1% was non-dialysable after 48 hr of dialysis, indicating that much of the acetaldehyde was reversibly bound to protein. When blood was incubated with 10-180 microM 14C-acetaldehyde for 1 hr and the plasma subjected to Sephacryl S300 gel filtration, 0.3-1.9% of the added radioactivity was found in the albumin and IgG fractions; this radioactivity is presumed to reside in both unstable and stable acetaldehyde-protein adducts. Plasma derived from whole blood which was incubated with 5-180 microM acetaldehyde and dialysed for 24 hr displayed cytotoxic activity against A9 cells. These data indicate that when 14C-acetaldehyde is incubated with whole blood, even at concentrations as low as 5-10 microM, a substantial proportion of the radioactive molecules form unstable cytotoxic adducts with plasma proteins and a much smaller proportion form stable adducts. Blood cells (mainly red cells) that were incubated with 14C-acetaldehyde were able to transfer radioactivity to cocultured K562 cells, supporting the possibility that not only acetaldehyde-modified plasma proteins but also acetaldehyde-modified blood cells may transport acetaldehyde and be cytotoxic in vivo.

Acetaldehyde↗
PubMed1994

Linkage disequilibrium in the region of the autosomal dominant polycystic kidney disease gene (PKD1).

The gene for autosomal dominant polycystic kidney disease (PKD1) is located on chromosome 16p, between the flanking markers D16S84 and D16S125 (26.6prox). This region is 750 kb long and has been cloned. We have looked at the association of 10 polymorphic markers from the region, with the disease and with each other. This was done in a set of Scottish families that had previously shown association with D16S94, a marker proximal to the PKD1 region. We report significant association between two CA repeat markers and the disease but have not found evidence for a single founder haplotype in these families, indicating the presence of several mutations in this population. Our results favor a location of the PKD1 gene in the proximal part of the candidate region.

Alleles↗
PubMed1994

Cervicography.

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Cervix Uteri↗
PubMed1993

3-Nitro-3,4-dihydro-2(1H)-quinolones. Excitatory amino acid antagonists acting at glycine-site NMDA and (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors.

3,4-Dihydro-2(1H)-quinolones, evolved from 2-carboxy-1,2,3,4,- tetrahydroquinolines and 3-carboxy-4-hydroxy-2(1H)-quinolones, have been synthesized and evaluated in vitro for antagonist activity at the glycine site on the NMDA receptor and for AMPA [(RS)-alpha-amino-3- hydroxy-5-methyl-4-isoxazolepropionic acid] antagonist activity. Generally poor potency at the glycine site is observed when a variety of electron-withdrawing substituents are attached to the 3-position of 3,4-dihydro-2(1H)-quinolones. The analogues 5-9 (IC50 values > 100 microM, Table I) exist largely in the 3,4-dipseudoaxial conformation (as evidenced by 1H NMR spectra), whereas the 3-cyano derivative (10, IC50 = 12.0 microM) has a relatively high population of the 3-pseudoequatorial conformer. The 3-nitro analogue (4, IC50 = 1.32 microM) has a pKa approximately 5 and thus exists at physiological pH as an anion with the nitro group planar to the quinolone ring. The general requirement of acidity for high affinity binding at the glycine/NMDA site is supported with the good activity of the other 3-nitro derivatives (13-21), all of which are deprotonated at physiological pH. The 3-nitro-3,4-dihydro-2(1H)-quinolones and 2-carboxy-1,2,3,4-tetrahydroquinolines show quite different structure-activity relationships at the 4-position. The unselective excitatory amino acid activity of 21 is comparable with 6,7-dichloro-quinoxaline-2,3-dione and 6,7-dichloroquinoxalic acid and this suggests similarities in their modes of binding to excitatory amino acid receptors. The broad spectrum excitatory amino acid antagonist activity of the 4-unsubstituted analogue 21 (KbNMDA = 6.7 microM, KbAMPA = 9.2 microM) and the glycine/NMDA selectivity of the other 3-nitro derivatives allows the proposal of a model for AMPA receptor binding which differs from the glycine binding pharmacophore in that there is bulk intolerance adjacent to the 4-position. Compound 21 (L-698,544) is active (ED50 = 13.2 mg/kg) in the DBA/2 mouse anticonvulsant model and is the most potent combined glycine/NMDA-AMPA antagonist yet reported, in vivo, and may prove to be a useful pharmacological tool.

Amino Acids↗
PubMed1993

[Guidelines of the Dutch College of Family Practitioners].

The Dutch College of General Practitioners (NHG) produces scientifically founded guidelines for general practice. They mark the emancipation of General Practice into a specialism in its own right and are used for education and quality control. They differ from national and international consensus guidelines, in that they are developed by general practitioners only, and that notice is taken of the specific predictive value of signs and tests in the setting of general practice. Moreover they usually go into more detail. NHG Standards are provided with additional Teaching Packages for use in comprehensive programme of continuous medical education. So far, 40 Standards have been published. They were very well received by general practitioners. Diffusion to the rest of the medical profession is under way.

Family Practice↗