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Biomedical subjects

T Smith

Publications and source records attributed to T Smith.

At least 379 records · Page 21Linked to original sources
PubMed1996

The role and extent of surgery in early invasive breast cancer.

The role of surgery in early invasive breast cancer is reviewed. Technologic developments and widespread use of screening mammography have allowed detection of smaller breast cancers that can be biopsied with minimally invasive procedures. Current treatment strategies include breast conservation therapy for the majority of early invasive breast cancers with local recurrence rates as low as 2%. The role of axillary dissection is being questioned in these early cancers. We review the current scientific data, which may lead to women with early breast cancers being treated with lumpectomy alone in the future, with axillary dissection being done in a scientific and highly selected fashion for the 10% to 30% of women who will benefit from that procedure.

Axilla↗
PubMed1996

Biokinetic behavior of technetium-99m-DMSA in children.

UNLABELLED: After intravenous administration of 99mTc-DMSA, biokinetic data were collected from studies on 24 children aged from 5 wk to 14.8 yr (15 normal and 9 with renal pathology). METHODS: Patients were imaged with a gamma camera up to 30 hr postinjection and the absolute activities in the kidneys, liver, spleen, bladder, knees and whole body were estimated using an attenuation-corrected conjugate counting technique. Renal uptake and elimination rates and urinary excretion of radioactivity were also measured. RESULTS: In children with normal renal function, maximal kidney uptake was 42.4% +/- 5.4% and was taken up with a half-time of 1.0 +/- 0.2 hr. Renal excretion amounted to 18.0% +/- 4.4% at 24 hr and was lowest in children aged less than 1 yr. In children with abnormal renal function, apart from the expected reduction in renal uptake there was evidence of wider variations in uptake rate and increased urinary excretion. Mean uptakes in liver and spleen were approximately 5% and 2%, respectively, in all patients and uptake in knees, assumed to reside in the metaphyseal growth complexes, was 1.4%. CONCLUSION: In children with normal renal function, there was little evidence of age-dependent biokinetic factors other than reduced urinary excretion and lower uptake in knees in children aged less than 1 yr. The results therefore suggest that a single biokinetic model may suffice for radiation dosimetry purposes in normal children irrespective of age.

Age Factors↗
PubMed1996

Radiation dosimetry of technetium-99m-DMSA in children.

UNLABELLED: Radiation dosimetry was performed on 24 children (aged 5 wk to 14.8 yr) who were undergoing routine diagnostic investigation of renal impairment with 99mTc-DMSA. METHODS: Organ doses were calculated using MIRDOSE 3 with biokinetic data obtained in previously described studies, and effective doses and effective dose equivalents were estimated. Interpolation by inverse weight between pediatric anthropomorphic phantoms was compared with age-matching to discrete phantoms. Administered activities were scaled by body surface area from the adult activity of 100 MBq and the resulting radiation doses in normal children were compared with those that would have resulted from a schedule based on body weight. RESULTS: The effective doses estimated by interpolation differed by up to 46% from those based on discrete phantoms and showed less variation. In children with normal bilateral renal function, the mean effective dose per administered activity was 0.91 +/- 0.08 mSv or 0.98 +/- 0.29 mSv by the two methods, respectively. Renal pathology reduced the effective dose, on average, by 15% of the value for normal patients. CONCLUSION: Over the pediatric age range, the uniformity of effective dose values was improved by scaling the administered activity according to body surface area rather than to body weight.

Adolescent↗
PubMed1996

Legionnaires' disease--a potential hazard of rationalisation.

The cases of two elderly patients who complained of general malaise after they had undergone ward transfer (due to rationalisation of the rehabilitation service) are discussed. Both were pyrexial and had signs of pneumonic consolidation. Subsequent investigation revealed that their symptoms were due to infection with Legionella pneumophila. Their cases highlight the problems associated with ward closures and the hazards of stagnant water.

Aged↗
PubMed1996

Are intravenous cannulae still being misused?

We have surveyed the use of intravenous cannulae (IVC) in a district general hospital. Of 354 patients interviewed on various wards, 125 (35.3%) had IVC in situ. The wrist was the commonest location for the cannulae (41.6%). An indication for cannula insertion was present in the majority (93.7%) of patients. Cannulae were left in situ even after their use had ceased, most commonly on wards for the elderly, and on these wards complications were more common. Other wards had specific IVC documentation, which resulted in fewer complications. Cannulae should be used for specific indications and should be reviewed daily for the development of complications and the need for their continued presence.

Adolescent↗
PubMed1996

Infant mortality in a deprived area of Papua New Guinea: priorities for antenatal services and health education.

This cross-sectional study of women was conducted in a deprived area of Papua New Guinea with an estimated infant mortality rate of 133/1000 live births. Mortality patterns derived from birth histories showed that neonatal deaths contribute proportionally more to infant mortality than postneonatal deaths, emphasizing the need for better care at delivery. To examine possible mechanisms for intervention, pregnant women were interviewed to determine patterns of antenatal clinic use, antimalarial drugs and micronutrient supplements given, and how much the women smoked. The results showed that the health system was failing to implement current routine supplementation and prophylaxis regimens, and that there was a need to revise national guidelines. A large proportion of pregnant women smoked during pregnancy, and this behaviour could be a target for future public health campaigns and health worker promotion advice to women.

Adolescent↗
PubMed1995

Hsp47 and cyclophilin B traverse the endoplasmic reticulum with procollagen into pre-Golgi intermediate vesicles. A role for Hsp47 and cyclophilin B in the export of procollagen from the endoplasmic reticulum.

Hsp47 and cyclophilin B (CyPB) are residents of the endoplasmic reticulum (ER). Both of these proteins are closely associated with polysome-associated alpha 1(I) procollagen chains. Hsp47 possesses chaperone properties early during the translation of procollagen while the cis/trans-isomerase properties of CyPB facilitate procollagen folding. In this report, we further investigate the interaction of these proteins with procollagen I during export from the ER. To inhibit vesicular budding and retain procollagen within the ER, cells were treated with the heterotrimeric G protein inhibitor mastoparan or calphostin C, a specific inhibitor of diacylglycerol/phorbol ester binding proteins. To arrest procollagen in pre-Golgi intermediate vesicles, cells were treated with guanosine 5'-3-O-(thio)triphosphate. Pulse-chase experiments of cells labeled with [35S]methionine followed by immunoprecipitation during the chase period with anti-procollagen, anti-Hsp47, and anti-CyPB antibodies were performed to reveal the relationship between Hsp47/CyPB/procollagen I. The distribution of procollagen, Hsp47, and CyPB to the ER and/or pre-Golgi vesicles was verified by immunofluorescence. Hsp47 and CyPB remained associated with procollagen retained within the ER. Hsp47 and CyPB were also associated with procollagen exported from the ER into pre-Golgi intermediate vesicles. Treatment of cells with cyclosporin A diminished the levels of CyPB bound to procollagen and diminished the rate of Hsp47 released from procollagen and the rate of procollagen secretion, suggesting that Hsp47 release from procollagen may be driven by helix formation. Also, these studies suggest that Hsp47 may resemble protein disulfide isomerase and possess both chaperone and anti-chaperone properties. During translation, high levels of Hsp47 are seen to limit protein aggregation and facilitate chain registration. Later, Hsp47 and/or CyPB and protein disulfide isomerase act as anti-chaperones and provide the basis for concentration of procollagen for ER export.

Amino Acid Isomerases↗
PubMed1995

Rapid crystallization of chemically synthesized hammerhead RNAs using a double screening procedure.

To find conditions for obtaining diffraction-quality crystals of a hammerhead RNA rapidly and reproducibly, we employed a "double screening" procedure in which we screened six different RNA synthetic constructs against 48 crystallization conditions using a newly devised sparse matrix. We obtained crystals immediately and diffraction-quality crystals of the sixth RNA construct within six months of initiating the screening of additional RNA sequences. The best crystals diffract to 2.9 A resolution when flash-cooled at synchrotron X-ray sources. Solid-support chemical synthesis combined with sparse matrix screening should allow rapid production of diffraction-quality crystals of a variety of small RNAs, reducing the time commitment for initiating such crystallography projects from several years to several months. The synthetic approach also makes introduction of modified bases to prevent self-cleavage and to generate isomorphous heavy-atom derivative crystals a rapid and straightforward process.

Base Sequence↗
PubMed1995

Proliferating hair cell precursors in the ear of a postembryonic fish are replaced after elimination by cytosine arabinoside.

Identified, proliferating S-phase cells in the postembryonic fish ear are known to be the precursors to new hair cells. It is not known, however, whether the ability to proliferate is restricted to a small population of cells. The ability of cells that are not normally in the cell cycle to enter S-phase was examined using the antimitotic drug cytosine arabinoside (ara-C). The normal population of S-phase cells in the saccule was destroyed by a single large dose of ara-C. Two weeks later, the presence of S-phase cells was evaluated using the S-phase marker bromodeoxyuridine. The results strikingly demonstrate that S-phase cells are replaced, since S-phase cells returned to the saccule in the same number as found in normal fish. The data are interpreted to suggest that a large number of nonsensory support cells are capable of entering the cell cycle and that some mechanism must regulate which of these are actually cycling at any given time.

Animals↗