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Biomedical subjects

A Waite

Publications and source records attributed to A Waite.

13 recordsLinked to original sources
PubMed2000

A mesoscale phytoplankton bloom in the polar Southern Ocean stimulated by iron fertilization.

Changes in iron supply to oceanic plankton are thought to have a significant effect on concentrations of atmospheric carbon dioxide by altering rates of carbon sequestration, a theory known as the 'iron hypothesis'. For this reason, it is important to understand the response of pelagic biota to increased iron supply. Here we report the results of a mesoscale iron fertilization experiment in the polar Southern Ocean, where the potential to sequester iron-elevated algal carbon is probably greatest. Increased iron supply led to elevated phytoplankton biomass and rates of photosynthesis in surface waters, causing a large drawdown of carbon dioxide and macronutrients, and elevated dimethyl sulphide levels after 13 days. This drawdown was mostly due to the proliferation of diatom stocks. But downward export of biogenic carbon was not increased. Moreover, satellite observations of this massive bloom 30 days later, suggest that a sufficient proportion of the added iron was retained in surface waters. Our findings demonstrate that iron supply controls phytoplankton growth and community composition during summer in these polar Southern Ocean waters, but the fate of algal carbon remains unknown and depends on the interplay between the processes controlling export, remineralisation and timescales of water mass subduction.

Atmosphere↗
PubMed2000

The effect of pH on the photophysics and photochemistry of disulphonated aluminum phthalocyanine

The results of a study of the effect of pH on the photophysics and photochemistry of di-sulphonated aluminum phthalocyanine (AlPcS2) in aqueous solution are presented. The pH dependence of the triplet quantum yield, fluorescence quantum yield, singlet-oxygen quantum yield, triplet lifetime, fluorescence lifetime and apparent dimerization constants is investigated and the results interpreted in terms of the pH dependence of the nature of the axial ligands. Evidence that the aluminum-axial ligand bond strength, rather than dimer binding energy that determines the extent of dimerization is provided by semi-empirical and ab initio calculations. Possible dimer structures obtained using ab initio calculations are discussed.

Journal Article↗
PubMed1999

Do immunoassays differentially detect different acidity glycoforms of FSH?

OBJECTIVE: The possibility of the carbohydrate residues of glycoproteins affecting their recognition in immunoassays is an important and unresolved issue. This study looked for evidence of differential recognition of FSH glycoform preparations, of variable isoelectric point (pI) and known molarity, using three routine assays employing different antibody configurations. DESIGN: Seven glycoform preparations with differing pI bands (between 3.8 and 5.5) were produced by isoelectric focusing of recombinant human FSH and the molecular weights determined by mass spectroscopy. Three concentrations of each glycoform were assayed and the results expressed relative to unfractionated material. From the relative responses, recognition differences between the assay methods and between the glycoform preparations were investigated. MEASUREMENTS: Three routine assays were employed: the commercially available Amerlite(R) enzyme immunoassay and Delfia(R) immunofluorometric assay, together with an in-house competitive two-site radioimmunoassay (RIA). RESULTS: Overall, the three assays gave the same relative responses for equivalent glycoforms, with the only exceptions involving small differences between some assay pairs for the fractions at the extremes of the pI range investigated. Within each assay type, differences (P < 0.05) of up to 33% existed between glycoforms of different pI, however, these differences showed no patterns or trends across the entire acidity range examined. CONCLUSIONS: Between the assay methods investigated in this study, few differences exist in the recognition of individual pI bands of FSH when expressed relative to a common unfractionated standard. Differences were apparent in the recognition of the different acidity glycoforms within each assay method, however, these were small and unlikely to be of clinical significance.

Analysis of Variance↗
PubMed1997

Case management: a week in the life of a clinical case management team.

This paper describes the work of a clinical case management core team (four nurses and an occupational therapist) during the course of a week. Information was gathered through non-participant observation of the team by two independent researchers. Transcripts produced from the data recorded were examined. From this, seven categories of activity were identified: planned client contact; unplanned client contact; family/carer contact; liaison; administration; team information sharing and supervision, training and personal development. These categories were felt to encompass the range of activities practised by the team. The amount of time that case managers spent engaged in these core functions was calculated. Detailed examples are presented. Results are discussed with reference to Kanter's components and principles of clinical case management.

Adult↗
PubMed1993

The comparative costs of care using apnoea monitors and scales in families with a cot death.

This paper reports the findings from a programme, which provided support to families with a subsequent baby following a cot death. One hundred families participated in the study. Fifty families were randomly allocated apnoea monitors, and the remainder provided with scales and weight charts for daily weighing. The results show that the parents in both groups expressed equal satisfaction with their designated method. However, compared with families allocated scales, those using apnoea monitors attended the child health clinics more often, and the number of contacts with the paediatrician was increased. They also had slightly more home and general practitioner contacts and hospital admissions. The capital and running costs of providing monitors was also greater for this group.

Apnea↗
PubMed1983

Cellular mechanisms of insulin release: the effects of vitamin D deficiency and repletion on rat insulin secretion.

To determine whether impaired insulin release from perifused rat islets of vitamin D-deficient (D-def) rats is a result of vitamin D-deficiency specifically or an associated decrease in food intake, we: 1) compared insulin release from islets of vitamin D-def rats with insulin release from islets of pair fed (pf) normal rats, and 2) measured the effects of 1,25(OH)2D3 treatment on food intake and insulin secretion from islets of D-def rats. Both vitamin D-def and pf normal rat islets showed significantly diminished insulin release in comparison with normal controls but were not different from each other. When D-def rats were repleted with 1,25(OH)2D3, food intake increased and insulin secretion improved during perifusion of rat islets. When D-def rats treated with 1,25(OH)2D3 were prevented from increasing their food intake in response to 1,25(OH)2D3 by pair feeding to a group of untreated D-def rats, insulin release from islets of treated rats was not significantly different from untreated D-def rats. To separate the effects of vitamin D deficiency from hypocalcemia, a group of vitamin D-def hypocalcemic rats was compared with a group of D-def normocalcemic rats. Normocalcemia did not reverse the defect in insulin release. In studies of cellular calcium uptake, both pf and D-def rat islets took up less calcium than normal islets but calcium uptake was not different between pf and D-def rat islets. Our studies suggest that vitamin D deficiency is associated with marked impairment of biphasic insulin release and that the decrease in food intake may account for this impairment at least in part.

Animals↗
PubMedDate not supplied

Repeat sudden unexpected and unexplained infant deaths: natural or unnatural?

BACKGROUND: There have been suggestions that when two or three unexpected unexplained infant deaths occur within a family they are more likely to be unnatural than natural. We aimed to estimate the probability that a second infant death is natural versus unnatural. METHODS: The Care of Next Infant programme (CONI) supports parents who have previously had an unexpected and apparently unexplained infant death and is currently available in over 90% of health districts in England, Wales, and Northern Ireland. We studied all deaths in 6373 infants who had completed the CONI programme by December, 1999. After a CONI death, we made detailed enquiries into the previous death and the CONI death, including a family interview, a review of autopsies, and case discussion. FINDINGS: 57 (8.9 per 1000) CONI infants died. Nine deaths were inevitable, and 48 were unexpected. 44 families lost one child, and two families lost two children. Of the 46 first CONI deaths, 40 were natural; the other six were probable homicides, five committed by one or both parents (two criminally convicted). The ratio of 40 natural to six unnatural deaths is 6.7 (95% CI 2.8-19.4). Enquiries identified 18 families with two SIDS(sudden infant death syndrome) deaths and two families with probable covert double homicides (ratio 9.0 [2.2 to 80.0]). There were no convictions in 13 incomplete cases. Families with three deaths are reported. INTERPRETATION: Repeat unexpected infant deaths are most probably natural.

Humans↗
PubMedDate not supplied

The influence of group size on children's competitive behavior.

The present research was designed to test the hypothesis that children would compete more in tetrads than in dyads. Twenty-two pairs of male and 14 pairs of female target children (N = 72) played a competitive game in both tetrads and dyads. Consistent with the hypothesis, male target children competed more in tetrads than in dyads. This hypothesis was not supported for females, however. Analyses of the dynamics of tetrads and dyads further demonstrated that based on a global measure of smiling, the emotional atmosphere was less positive in tetrads than in dyads. The causes and consequences of interaction in different sized social groups are discussed.

Child↗