Biomedical subjects

S Chambers

Publications and source records attributed to S Chambers.

At least 55 records · Page 3Linked to original sources

PubMed1992

Doppler umbilical artery flow velocity waveforms in diabetic pregnancy.

OBJECTIVE: To assess the effect of uncomplicated diabetes on umbilical artery flow velocity waveforms (FVWs); to investigate the relation between glycaemic control and FVWs and the predictive value of umbilical artery FVWs for antenatal fetal compromise. DESIGN: Prospective descriptive study. SETTING: A large diabetic pregnancy clinic in a teaching hospital. SUBJECTS: 128 pregnancies complicated by diabetes mellitus. 170 non diabetic women with no pre-existing or pregnancy complications. INTERVENTIONS: In diabetic pregnancies, umbilical artery resistance index (RI) Doppler recordings and glycosylated haemoglobin were measured every 2 weeks from 28 weeks. MAIN OUTCOME MEASURES: Umbilical artery RI and antenatal fetal compromise defined as a non reactive, decelerative cardiotocograph and/or a biophysical profile score persistently less than 6 and leading to immediate caesarean section. RESULTS: Uncomplicated diabetic pregnancies had FVW values similar to those in the non-diabetic range. Glycaemic control was unrelated to umbilical artery FVW values. Abnormal umbilical artery RI was found in nine pregnancies, these were more likely to show evidence of fetal compromise and to be associated with birthweights of less than 50th centile. In seven pregnancies there was evidence of fetal compromise, but only three of these pregnancies had abnormal FVW values. CONCLUSIONS: The non-diabetic range of umbilical artery RI values is appropriate for diabetic pregnancies. Long-term glycaemic control, within the range in this study, does not seem to affect umbilical artery RI. Abnormal umbilical artery RI is a significant predictor of fetal compromise in diabetic pregnancy, but fetal compromise can occur in association with normal RI values. Undue reliance should not be placed on normal FVW values in diabetic pregnancies.

Apgar Score↗

PubMed1992

The helix-turn-helix motif of sigma 54 is involved in recognition of the -13 promoter region.

Residue Arg-383 in the proposed helix-turn-helix motif of the novel RNA polymerase sigma factor sigma 54 has been changed by site-directed mutagenesis to all possible alternative amino acids. Only two mutants, RK383 and RH383, are active in promoting transcription from either the glnAp2 promoter or the nifL promoter. We constructed a set of mutant derivatives of glnAp2 such that each base in the conserved GG and GC doublets at -24 and -12 was changed to all possible alternatives. All 12 mutant glnAp2 promoters showed a marked promoter-down phenotype with wild-type sigma 54, but RK383 suppressed changes of both G to C and G to T at -13. This result suggests that the sigma 54 helix-turn-helix is involved in recognition of the -13 region of sigma 54-dependent promoters.

Amino Acid Sequence↗

PubMed1991

Vaginal infections, cervical ripening and preterm delivery.

A prospective study is presented which addresses the relative effect of cervicovaginal infection and precocious maturation of the uterine cervix on preterm delivery. From April 1981 through December 1983, a total of 5758 pregnant women were checked by means of a vaginal examination at every prenatal visit and a research for bacterial cervicovaginal infection whenever abnormal signs were observed. The study reveals that vaginal infection has no measurable effect when observed during the second trimester of pregnancy, and a small effect during the third trimester. This means that infection of the vagina or/and the cervix may be demonstrated as a risk factor only when the cervix is short before 28 weeks or open before 37 weeks.

Bacterial Infections↗

PubMed1991

A needs-based methodology for allocating health care resources in Ontario, Canada: development and an application.

In an attempt to limit its health care expenditures, Ontario is, as one option, exploring the possibilities of a capitated system for service delivery payments as opposed to the present mixture of global budgets and fee-for-service. After reviewing the literatures on capitation (primarily American) and on resource allocation (primarily British), the paper sets out to establish a capitation rate, based on 'need' and not prior use, for a range of health services in the northern Ontarian community of Fort Frances-Rainy River. The difficulties and limitations of the needs-based approach are explored. The results reported show the setting of the local population characteristics against provincial average health care utilization data to generate expected use rates, which are then adjusted for need and other factors, particularly relative costs and sparsity. Finally these adjusted rates are applied to current provincial expenditures to derive a target share. This target is then expressed in relation to the planning population to derive the capitation rate.

Budgets↗

PubMed1988

Can audit improve patient care? Effects of studying use of digoxin in general practice.

A survey of monitoring of digoxin treatment in five practices examined the indications for prescribing digoxin, its long term use, and how its use could be monitored. These data were used to generate a protocol for monitoring treatment with digoxin in general practice. The findings of the survey and the protocol were distributed to and discussed with all the partners in the practices participating in the study. One year later similar analysis showed that record keeping (recording of pulse rate and rhythm) had improved significantly in the group of principals carrying out the audit but not in other principals in these practices. Audit may change only the auditors.

Adolescent↗

PubMed1988

Umbilical artery Doppler flow velocity waveform: the outcome of pregnancies with absent end diastolic flow.

We have studied doppler recordings of flow velocity waveform of the umbilical artery in 380 high-risk pregnancies and 160 patients with uncomplicated pregnancies. The results were not used in clinical management. In 24 cases, all in high-risk pregnancies, there was absence of end diastolic flow (AEDF). Four babies died, 22 out of 24 weighted less than the 5th centile for gestation and 20 were delivered by Caesarean Section. With only four exceptions, all fetuses showed other evidence of antenatal fetal compromise, though this was delayed in some cases for up to 24 days. AEDF does not appear to prejudice neonatal outcome. All six babies born weighing 750-999 g survived. In addition, 4 patients continued their pregnancy for 3-6 weeks after the first doppler with AEDF. Only one of the 4 developed other evidence of fetal compromise and two had vaginal deliveries. In our experience, AEDF is found only in abnormal pregnancy, and is a very serious sign of likely fetal compromise. It is an indication for extremely careful surveillance but not necessarily an indication for delivery.

Blood Pressure↗

PubMed1987

Comparative study of iron mobilization from haemosiderin, ferritin and iron(III) precipitates by chelators.

The heteroaromatic chelators 1,2-dimethyl-3-hydroxypyrid-4-one, maltol, mimosine and 2,4-dihydroxypyridine-N-oxide, have been shown to mobilize iron from human spleen haemosiderin, ferritin and also from iron(III) precipitates, all containing equal amounts of iron, at physiological pH. In the case of almost every chelator, the least-solubilized polynuclear iron form was ferritin, whereas haemosiderin was more soluble and the iron(III) precipitate the most soluble of all. Most of the chelators were more efficient than desferrioxamine at releasing iron from ferritin, but less efficient in the removal of iron from the other two polynuclear iron forms. It is suggested that the chelator differences in iron mobilization may be related to variations in the chelator molecular structure, the protein structure, iron forms and in the mechanism of iron release.

Deferiprone↗

PubMed1987

Indwelling urinary catheters in the elderly. Relation of "catheter life" to formation of encrustations in patients with and without blocked catheters.

In order to define the natural history of indwelling urinary catheters in the elderly, 50 patients aged 65 years or older were followed. Their catheters had been in place for a mean of 33.2 days. When removed, 40.4 percent were blocked or showed poor flow. After the catheters were changed, the 14-day "catheter life" was 78 percent. About half the population had blocked catheters. They had a 14-day "catheter life" of only 31.8 percent (p = less than 0.01). Patients with blocked catheters ("blockers") excreted more alkaline urine, calcium, protein, and mucin than patients without blocked catheters ("nonblockers"), but urea-splitting bacteria were no more frequent. The mortality was not significantly different. Flow of water through catheters was closely related to extent of encrustations. Encrustations formed uniformly throughout the catheter lumen except when the tip was obstructed. The distribution and number of species of microorganisms (three and a half per specimen) were virtually identical in catheter and bladder urine, but the counts in the catheter urine were more frequently greater than 100,000 cfu/ml (p = less than 0.01). Patients with blocked catheters appear to be metabolically different from patients without blocked catheters and should have their catheters changed at seven to 10 days to avoid obstruction.

Aged↗

PubMed1987

Formation of encrustations on indwelling urinary catheters in the elderly: a comparison of different types of catheter materials in "blockers" and "nonblockers".

In order to determine the effect of catheter materials on formation of encrustations in long-term indwelling urinary catheters in the elderly we performed a crossover study utilizing commercially available silicone, silicone-coated, teflon-coated and latex catheters that were left in place for 14 days. The study was conducted with #18 french catheters fitted with a 30 ml. balloon since smaller size catheters frequently fell out spontaneously. The distinction between patients who were "blockers" and "nonblockers" was found to be clinically useful since "nonblockers", who constituted about half the population, did well regardless of type of catheter material used. Formation of encrustations and blockage was significantly less in "blockers" with silicone than with teflon-coated or latex catheters. The more rapid flow-time through silicone catheters appears to be related to a larger bore. Although this study supports the use of silicone catheters for "blockers" on long-term drainage the results should not be interpreted to imply that they are preferable to other types of catheters for short-term use or to changing less expensive catheters more frequently when needed.

Aged↗

PubMed1987

Morbidity and mortality associated with indwelling urinary catheters in elderly patients in a nursing home--confounding due to the presence of associated diseases.

A prospective study was conducted in a nursing home among elderly residents treated with and without indwelling catheters. Most of the patients were white females with a mean age of 82.3 years. The mortality at 6 months among catheterized patients was 30.2% compared with 10.1% among the noncatheterized groups (P less than 0.001). Patients with catheters differed significantly from those without in having more impaired mental status and diminished activities of daily living. They also differed significantly for eight of 30 diseases. Cerebrovascular and hypertensive disease were significantly more common in catheterized patients. In contrast, fractures and musculoskeletal disorders were significantly more common among noncatheterized patients. Catheterized patients had significantly more days with fever and symptomatic urinary tract infections and received antibiotics more often than did noncatheterized patients. We conclude that: (1) direct comparisons of morbidity and mortality among catheterized and noncatheterized populations are not valid because of confounding by the presence of associated life-threatening illnesses; and (2) catheterized patients have more clinical episodes of urinary tract infections and fever and are treated more frequently with antibiotics.

Activities of Daily Living↗

PubMed1987

New synthetic approach and iron chelating studies of 1-alkyl-2-methyl-3-hydroxypyrid-4-ones.

The major diseases of iron metabolism are iron deficiency anaemia, which could be treated using Fe2+ or Fe3+ salt supplements, and iron overload, which could arise either from an increased gastrointestinal absorption of iron or from recurrent blood transfusions. While the former form of iron overload could be treated by phlebotomy the latter requires the use of a chelator. Desferrioxamine is the only clinically available chelator for the treatment of iron overload but its use worldwide is limited because it is expensive and orally inactive. Several alpha-ketohydroxy heteroaromatic chelators have been synthesised and tested for their iron binding properties at physiological pH. The synthetic route involves the benzylation of the hydroxyl group of maltol using benzyl chloride, the conversion of the benzylated maltol to the 1-alkyl benzylated pyridine derivative by introducing the corresponding alkylamine in alkaline conditions and the cleavage of the benzyl group in acid to form the 1-alkyl-2-methyl-3-hydroxypyrid-4-one. All the chelators are water soluble and stable at a wide range of pH, forming stable, water soluble, coloured iron complexes with a molar ratio of approximately 3 chelator: 1 iron at pH 7.4 and lower molar ratio of chelators to iron complexes at acidic pH. When the 1-methyl, 1-ethyl and 1-propyl, -2-methyl-3-hydroxypyrid-4-ones were mixed at pH 7.4 with transferrin, ferritin and haemosiderin substantial amounts of iron were released.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical Phenomena↗

PubMed1986

Microbiology.

Explore the source record for details and available documents.

Animals↗

PubMed1985

Hormone and haemodynamic effects of angiotensin II infusion during captopril treatment for heart failure.

Withdrawal of captopril therapy for cardiac failure results in increments in plasma cortisol, noradrenaline and heart rate. To determine whether these changes related to the concomitant rise in circulating angiotensin II, we infused angiotensin II at 0.5, 2, 4 and 8 ng/kg/minute, each infusion lasting for 1 hour, in 4 patients during maintenance captopril therapy for heart failure. A control solution of 5% dextrose was infused over a similar time interval on a separate day. The study was performed under metabolic balance conditions, with constant body posture and continuous haemodynamic monitoring. Angiotensin II induced the expected rise in arterial pressure and in plasma aldosterone. In contrast the diurnal decline in plasma ACTH and cortisol was not altered, and no changes in noradrenaline or heart rate were observed. Plasma angiotensin II appears to have little or no effect on ACTH, cortisol, noradrenaline and heart rate under the conditions of this study.

Adrenocorticotropic Hormone↗

PubMed1985

The osmoprotective properties of urine for bacteria: the protective effect of betaine and human urine against low pH and high concentrations of electrolytes, sugars, and urea.

Growth of Escherichia coli was inhibited in a defined minimal medium by high concentrations of electrolytes and sugars in direct relation to their osmotic strength. Choline, betaine, proline, and human urine increased resistance to these substances. In contrast, the toxic effect of urea was not altered directly by betaine or urine, but was reduced in the presence of other osmolytes. The osmolyte protective effect was augmented by betaine. The osmoprotective effect of betaine and urine was confirmed with 40 strains of enteric bacteria. Urine from 19 healthy subjects contained osmoprotective activity greater than that observed with betaine. A methanol extract of urine was found to be highly protective. Although betaine was present in the extract, it could not account for all the protective activity. Urine contains additional low-molecular-weight osmoprotective agents.

Anti-Bacterial Agents↗

PubMed1985