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Biomedical subjects

B J Stevens

Publications and source records attributed to B J Stevens.

At least 19 recordsLinked to original sources
PubMed2001

Assessment and management of pain in neonates.

Neonates are capable of experiencing pain from birth onwards. An impressive body of neuroanatomical, neurochemical and biobehavioural evidence, which has accumulated over the past 2 decades, supports this capability. This evidence mandates health professionals to attend to the prevention, elimination, or at the very least, control of pain for infants. This mandate is essential since pain is known to have both immediate and long term effects, especially if pain is untreated and is severe, prolonged or frequently experienced. Therefore, pain must be assessed frequently, not only to measure location, intensity and duration but also to determine the effectiveness of interventions implemented to control pain. An impressive array of measures for assessing acute pain in infants exists which incorporates valid pain indicators in this population. However, there is a need to develop new measures to assess chronic pain conditions and pain in infants in acute situations.

Humans↗
PubMed1997

Effectiveness of oral sucrose and simulated rocking on pain response in preterm neonates.

Feeding and carrying have been interventions used by caregivers throughout history in relieving distress in infants. Recent studies on the food substance sucrose have elucidated the comforting effect of the taste component of feeding while studies of rocking have examined the comforting effect of the vestibular component of carrying. The purpose of this study was to determine the effectiveness of sucrose and simulated rocking alone and in combination on diminishing pain response in preterm neonates undergoing routine heelstick procedure in the neonatal intensive care unit (NICU). Preterm infants (n = 85) between 25-34 weeks post-conceptual age (PCA) and 2-10 days postnatal age (PNA) were randomly assigned to one of four conditions for routine heelstick procedure. The conditions were (1) sucrose alone: 0.05 ml of 24% sucrose was placed on the anterior surface of the tongue just prior to the lancing of the heel; (2) simulated rocking alone: 15 min prior to and during the heelstick procedure, the infant was swaddled and put on an oscillating mattress; (3) combination of sucrose and simulated rocking; and (4) placebo: 0.05 ml sterile water administered just prior to heelstick. Physiological (heart rate) and behavioural (facial actions) responses from baseline across 90 s following heelstick were scored second-to-second. Facial actions were analysed with repeated measures MANCOVA and heart rate with repeated measures ANCOVA. Behavioural state and gestational age were covariates. The groups that received sucrose alone or in combination with simulated rocking showed less facial actions indicative of pain than the rocking alone or control group. The addition of rocking to the sucrose condition tended to further blunt the facial expression of pain, but this enhancement did not reach a significant level. Heart rate was not decreased by any intervention compared to the control condition. Although the simulated rocking did promote quiet sleep, which has been reported in earlier studies to blunt pain response, there was no difference between simulated rocking and control groups in either facial expressions indicative of pain or heart rate. The implication of these results is that sucrose, but not simulated rocking may be a means of diminishing pain from minor procedures in preterm infants. Further research is needed on the use of sucrose for more than one procedure as well as examining the contact component of natural rocking, as opposed to simulated rocking.

Administration, Oral↗
PubMed1996

Experience in a neonatal intensive care unit affects pain response.

OBJECTIVE: To determine the effect of being in the neonatal intensive care unit (NICU) on pain responses in infants of 32 weeks' postconceptual age (PCA). DESIGN: A cross-sectional comparative design was used. SETTING: Two level III NICUs, each in metropolitan, university teaching hospitals. PATIENTS: Infants of 32 weeks' PCA born within the past 4 days (the newly born group; n = 53) were compared with infants of the same PCA who had been born 4 weeks earlier (the earlier-born group: n = 36) and had spent that time in an NICU. OUTCOME MEASURES: Heart rate, oxygen saturation levels, and facial actions were used as outcomes in a between-group repeated measures analysis of variance across the heel stick procedure. Background variables of Apgar, weight at birth and data collection, severity of illness, age group, and total number of invasive procedures were entered into a stepwise regression. RESULTS: The two groups responded differently to the heel stick: the earlier-born infants had less behavioral manifestations of pain than the newly born infants. The number of invasive procedures was the primary factor that explained those behavioral differences, with Apgar as a second explanatory factor. The earlier-born infants had higher heart rates and lower oxygen saturation than the newly born infants before as well as during the procedure. These physiological differences were explained by the perinatal factors of age at birth and birth weight. CONCLUSION: Preterm infants who spend PCA weeks 28 through 32 in an NICU are less mature in their pain response than newborn premature infants of 32 weeks' PCA. Greater frequency of invasive procedures is associated with behavioral immaturity, whereas birth factors are associated with physiological immaturity.

Age Factors↗
PubMed1992

Mechanism of action of cyclic beta-1,2-glucan synthetase from Agrobacterium tumefaciens: competition between cyclization and elongation reactions.

We have examined some aspects of the mechanism of cyclic beta-1,2-glucan synthetase from Agrobacterium tumefaciens (235-kDa protein, gene product of the chvB region). The enzyme produces cyclic beta-1,2-glucans containing 17 to 23 glucose residues from UDP-glucose. In the presence of added cyclic beta-1,2-glucans (> 0.5 mg/ml) (containing 17 to 23 glucose residues), the enzyme instead synthesizes larger cyclic beta-1,2-glucans containing 24 to 30 glucose residues. This is achieved by de novo synthesis and not by disproportion reactions with the added product. This is interpreted as inhibition of the specific cyclization reaction for the synthesis of cyclic beta-1,2-glucans containing 17 to 23 glucose residues but with no concomitant effect on the elongation (polymerization) reaction. Temperature and detergents both affect the distribution of sizes of cyclic beta-1,2-glucans, but glucans containing 24 to 30 glucose residues are not produced. We suggest that the size distribution of cyclic beta-1,2-glucan products depends on competing elongation and cyclization reactions.

Agrobacterium tumefaciens↗
PubMed1990

Use of oligonucleotide probes to identify members of two-component regulatory systems in Xanthomonas campestris pathovar campestris.

Two-component regulatory systems comprising a sensor and a regulator protein, both with highly conserved amino acid domains, and commonly genetically linked, have been described in a range of bacterial species and are involved in sensing environmental stimuli. We used two oligonucleotide probes matching the postulated coding regions for domains of sensor and regulator proteins respectively in Xanthomonas campestris pathovar campestris (Xcc) to identify possible two-component regulatory systems in Xcc. Two different fragments of Xcc DNA with homology to both of these probes were cloned. The DNA sequence of part of one of these fragments encompassed a potential open reading frame (ORF), the predicted amino acid sequence of which had extensive homology with regulator proteins of two-component regulatory systems. Analysis of the predicted amino acid sequence for the 3' end of an adjacent ORF revealed a very high level of homology with the C-terminal end of sensor proteins. Strains of Xcc with Tn5-induced mutations in the regulator gene were affected in extracellular polysaccharide production, and also in resistance to salt and chloramphenicol. No effects of mutation in the second clone were observed.

Amino Acid Sequence↗
PubMed1988

Changes in composition and structure of wheat bran resulting from the action of human faecal bacteria in vitro.

Cell-wall material of wheat bran was incubated with human faecal bacteria for 24-72 h and the resulting structural changes were studied by methylation analysis. Of the carbohydrate content, approximately 39% was degraded after 24 h, increasing to only 44% after 72 h. Arabinoxylans and mixed-linkage beta-D-glucans from the aleurone layer were degraded preferentially. After treatment of the bran with alkali, the extent of degradation was increased three-fold as a result of saponification of ester cross-links which facilitated increased degradation of the polymers from both the aleurone and outer, lignified, layers. There was evidence that ester linkages between the glucuronosyl residues, attached to O-2 of the (1----4)-linked xylosyl residues, and phenolic groups of lignin were also saponified. The treatment with alkali also rendered the cellulose more susceptible to bacterial attack. The alkali-soluble acidic arabinoxylan fractions of the bran were degraded readily by bacterial action, but the xyloglucans cross-linked to arabinoxylans by phenolics were relatively resistant.

Arabinose↗
PubMed1985

Immunolocalization of the 100 K nucleolar protein in CHO cells.

The localization of a major nucleolar protein with a molecular weight of 100,000 has been followed in Chinese hamster ovary cells using specific antibodies to this protein and immunocytochemical techniques. By immunofluorescence and immunocytochemistry at ultrastructural level in situ, the 100 K protein was detected abundantly in the nucleolus of interphase cells. In exponentially growing cells, the dense fibrillar component was shown to contain more 100 K protein than the granular RNP component but both the nucleolar components were positively immunostained. Fibrillar centers consistently showed weaker or no staining. The 100 K association with the preribosomal RNP components of the interphase nucleolus supports evidence for a role of this protein in pre-rRNA transcription and preribosomal processing.

Animals↗
PubMed1985

Immunolocalization of the 100 kDa nucleolar protein during the mitotic cycle in CHO cells.

The localization of a major nucleolar protein with a molecular weight of 100,000 has been followed during mitosis in Chinese hamster ovary CHO cells using specific antibodies to this protein and immunocytochemical techniques. The 100 kDa protein was visualized at discrete sites on metaphase chromosomes, corresponding to nucleolus organizer regions, and in large, immunostained nucleolar remnants that are discarded in the cytoplasm after nucleolar disintegration. After mitosis, the 100 kDa protein was shown to play an early role in nucleolar reformation. It was first detected in small deposits around the anaphase chromosomes. In telophase, the protein accumulated simultaneously in prenucleolar bodies and in the reforming nucleoli. The early presence of the 100 kDa protein in the telophase nucleus suggests that it is essential for the reestablishment of nucleolar function after mitosis. Thus this protein is present throughout the CHO cell cycle, an observation which supports the hypothesis that it plays a fundamental role in cell organization.

Animals↗
PubMed1984

Electrothermal atomic absorption determination of aluminum in tissues dissolved in tetramethyl ammonium hydroxide.

In this rapid, precise method for the accurate determination of aluminum in biological tissue, the only preparative step required is the dissolution of the sample in hot aqueous tetramethyl ammonium hydroxide, followed by dilution with ethanol. Aluminum is measured by electrothermal (graphite furnace) atomic absorption spectroscopy, with direct reference to aqueous standards. The CVs for the method within-day and day-to-day are 3.0% and 6.8%, respectively. Analytical recovery of added aluminum is 86 to 108%, and matrix effects are minimal. Measurement of aluminum in tissue from normal laboratory rats and rats injected with aluminum gave values close to those found by an acid digestion method, but higher than those obtained by extraction with a saturated solution of ethylenediaminetetraacetate.

Aluminum↗
PubMed1981

The role of the nurse executive.

It is vital that the nurse executive critically examine her role conception and her role performance. She should take an activist's position in regard to her role, making it the sort of role it should be rather than merely filling the role as others expect or anticipate. Every role has much elasticity in it, and this enables the nurse executive to manipulate and alter the role if she tries. She also should learn to be sensitive to attempts to cast her in lesser roles than those which accord with her position in the organization. Role is an excellent concept by which to consider and link such various elements of management as managerial skills and abilities, managerial functions, organizational status, and strategies for management.

Administrative Personnel↗