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Biomedical subjects

R Moor

Publications and source records attributed to R Moor.

8 recordsLinked to original sources
PubMed2001

Pain assessment in a children's A&E: a critical analysis.

In this particular children's A&E department it is evident that pain assessment is a high priority among the nursing staff. Pain is routinely assessed on every child during triage, so analgesia is given as soon as possible and children are not left suffering pain for an unnecessary length of time. However, because pain is not routinely reassessed it is often unknown whether the pain has been fully relieved. It appears that not all the resources available for assessing a child's pain are utilised, resulting in the possibility that not all aspects of a child's pain are assessed. Pain is assessed using the child's self reports or nurses' observations. It has been shown that these are not always appropriate and there is need to use a number of different tools for assessing a child's pain. There is also the need for a validated tool to assess pain in younger children. When referring back to McGrath and Unruh's (1987) definitions of pain measurement and pain assessment, it could be concluded that nurses in the children's A&E department measure pain, but, due to the lack of emphasis which is placed on the different aspects of pain and the limited range of tools which are used, they do not assess pain effectively. In order for pain assessment to be improved, nurses need to be made aware of the different aspects of pain and different tools which are available to assess them in children. This could be initiated by implementing the RCN (1999) guidelines for pain recognition and assessment in children.

Child↗
PubMed2001

Maturation of pig oocytes in vivo and in vitro.

In this review the concept that the origins of embryonic failure occur during oocyte development is explored. The four factors that determine oocyte viability, namely a normal growth phase, adequate follicle cell support during maturation, the completion of intracellular reprogramming before fertilization and the functioning of oocyte surveillance mechanisms, form the four sections of this review. The viability of pig oocytes at the end of the growth phase is compromised by presumptive spontaneous meiotic progression and by morphological heterogeneity. Determining the percentage and identity of viable dictyate oocytes, and identifying the reasons for the loss of viability, are key areas of future investigation. Although the requirement for follicle cell support during maturation is already established, little is yet known about the underlying signals and their transmission to the oocyte. The analysis of the action and nature of somatic signals will provide the foundation for further advances in the maturation of oocytes in vitro. Signalling cascades in oocytes control both the translation of masked mRNA and the modification and spatial localization of resultant proteins. The interdependent nature of this control system explains why inappropriate signals during maturation lead to subsequent embryonic mortality. Chromosomal errors during meiosis and early mitosis accumulate because of the leaky nature of the checkpoint system during the maternally regulated part of development: effective cell cycle surveillance is established only after the activation of the embryonic genome. In summary, we emphasize that the quality of the dictyate oocyte and the provision of appropriate signals in vitro are the principal determinants of maturational success.

Animals↗
PubMed2000

Selective requirement for Cdc25C protein synthesis during meiotic progression in porcine oocytes.

Fundamental differences between meiosis and mitosis suggest that the shared central cell cycle machinery may be regulated differently during the two division cycles. This paper focuses on unique features of Cdc25C protein function during meiotic progression. We report on the existence of oocyte-specific CDC25C transcripts that differ from their somatic counterparts in the 3' untranslated region. While CDC25C mRNA levels remain constant in fully-grown oocytes, corresponding protein levels increase progressively during maturation to a maximum at metaphase II. Elevation of Cdc25C protein levels in G2-oocytes by mRNA injection failed to increase MPF-kinase levels or to induce premature entry into M-phase. Likewise, antisense-induced arrest of translation (translational arrest) had no effect on chromosome condensation, nucleolar disassembly, or nuclear membrane contraction. By contrast, translational arrest inhibited subsequent events including membrane disassembly and spindle formation. Neither up- nor down-regulation of Cdc25C synthesis after metaphase I plate formation influenced progression to metaphase II. However, translational arrest during metaphase resulted in incomplete chromosome decondensation and abnormal pronuclear membrane assembly after activation. We conclude that Cdc25 protein, translated from unique transcripts, is preferentially located in the oocyte nucleus and is essential for progress through late diakinesis. Subsequently, new synthesis of Cdc25C protein is required for the orderly transition from meiotic to mitotic cell division.

Animals↗
PubMed1989

[High-speed motion picture analysis of bone fractures].

Torsional fractures of plastic and cadaver tibiae were investigated using high speed cinematography. The bones were fractured while immersed in water. With greater than 9000 frames/sec the fracture was displayed in about 5 frames showing the progression of the fracture lines. The immersion in water made a strong implosion visible which may result in considerable tissue damage in vivo.

Biomechanical Phenomena↗
PubMed1986

Laser Doppler flowmetry for bone blood flow measurement: correlation with microsphere estimates and evaluation of the effect of intracapsular pressure on femoral head blood flow.

Laser Doppler flowmetry (LDF) was used to measure bone blood flow in the rabbit femoral head and femoral condyles. To correlate the LDF output signal blood cell flux to in vivo blood flow, simultaneous measurements using LDF and 85Sr-labeled microspheres were made in an adult rabbit model. There was no correlation between the two methods for blood flow in the femoral condyles and the correlation between the two methods for blood flow in the femoral head does not achieve statistical significance. An LDF signal of 0.4 V was approximately equal to a microsphere measured flow rate of 0.4 ml blood/g bone/min. The strength of the correlation in the latter case may have been affected by (a) large arteriovenous shunts, (b) inadequate mixing of the microspheres with a left ventricular injection, and (c) insufficient numbers of microspheres present in the bone samples with which to satisfy the mathematical requirements of the microsphere method. When LDF was used to evaluate the effect of elevated intracapsular pressure on femoral head blood flow in skeletally mature rabbits, femoral head subchondral bone blood flow declined with increasing intracapsular pressure from a baseline value of 0.343 +/- 0.036 to a value of 0.127 +/- 0.27 at 120 cm of water pressure. The decline in femoral head blood flow was statistically significant at pressures of 40 cm of water or higher (p less than 0.001), and evaluation of sections of the proximal femora made from preterminal disulphine blue injections confirmed these findings. Intracapsular tamponade has an adverse effect on femoral head blood flow beginning well below central venous pressure and should be considered in the pathophysiology of posttraumatic and nontraumatic necrosis of the femoral head. Laser Doppler flowmetry was easy to use and appears to be a reproducible technique for evaluating femoral head blood flow, offering distinct advantages over the microsphere technique for measuring bone blood flow. Further studies of the in vivo calibration of the LDF method for bone blood flow are necessary for the method to have potential for clinical application.

Animals↗
PubMedDate not supplied

Chemically enucleated mouse oocytes: ultrastructure and kinetics of histone H1 kinase activity.

The objective of the study was to characterize the ultrastructure changes and biochemical mechanisms underlying the expulsion of the entire chromosome complement in chemically enucleated mouse oocytes. The ultrastructural studies demonstrated that the morphology of cytoplasts produced by etoposide-cycloheximide treatment were indistinguishable from intact metaphase I and II oocytes. Moreover, polar bodies formed by chemical enucleation were in almost all cases completely separated from the parent cytoplast and differed from normal polar bodies only in their chromatin content morphology and because they contained a slightly higher number of cytoplasmic organelles. The mode of polar body formation, however, in normal and chemically enucleated oocytes differs substantially: spindle involvement is important for normal polar body extrusion but plays no part in the protracted expulsion of chromosomes during chemical enucleation. After etoposide-cycloheximide treatment, histone H1 kinase activity remains high for the ensuing 6-8 h before declining gradually to basal levels 14 h after treatment. The expulsion of the polar body occurred only after the slowly declining H1 kinase activity reached basal levels. The activity of this kinase rose sharply to reach maximal levels within 4 h when the enucleated oocytes were removed from the inhibitor-supplemented medium and placed in normal medium. The findings in this paper indicate that cytoplasts produced by chemical enucleation are morphologically normal, thus suggesting that these enucleated cells are suitable for cloning studies. Although effective in mouse oocytes, we postulate that certain modifications to the enucleation technology are necessary before a reliable non-invasive protocol for ungulate oocytes will be available.

Animals↗
PubMedDate not supplied

Mouse oocyte maturation: the effect of modified nucleocytoplasmic ratio.

Fully grown mouse oocytes isolated from large antral follicles and cultured in vitro complete their maturation up to the second metaphase with extrusion of the first polar body (1PB) with a 40/50 proportion (80%). When their cytoplasmic volume is, however, reduced before the onset of culture, the frequency of oocytes completing maturation gradually decreases. In the half oocytes, 66% (33/50) extruded 1PB, while in third oocytes the proportion was 57% (28/49) and in quarter oocytes no polar bodies were extruded. The time course of germinal vesicle breakdown was also delayed in comparison to the decreased cytoplasmic volume. Moreover, the isolated germinal vesicles surrounded with a thin cytoplasmic rim only remained intact after a prolonged culture. The full competence of complete maturation can be restored by fusion of an additional cytoplast to the manipulated nucleate parts. We postulate that a critical nucleocytoplasmic volume ratio is absolutely necessary for normal maturation in mammalian oocytes.

Animals↗