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Biomedical subjects

S Blackburn

Publications and source records attributed to S Blackburn.

At least 19 recordsLinked to original sources
PubMed2001

Factors influencing the distributions of polyunsaturated terpenoids in the diatom, Rhizosolenia setigera.

Polyunsaturated highly branched isoprenoid (HBI) hydrocarbon distributions of laboratory cultures of five strains of the planktonic diatom Rhizosolenia setigera (Brightwell) are shown herein to be highly variable. Some strains produced both haslenes with from three to five double bonds and rhizenes. The haslenes comprised not only Delta5 alkenes but also those with C7(20) unsaturation, including hasla-7(20),9E,Z, 23-trienes and hasla-7(20),9E,Z-13, 23-tetraenes. The rhizenes contained C7(25) unsaturation and the vinyl moiety common to all algal haslenes so far characterised. The effects of temperature and salinity on HBI composition, along with isotopic content, were determined in strain CS 389/A. Increase in growth temperature from 18 to 25 degrees C increased the degree of unsaturation in the haslenes and E to Z isomerisation in the triene. There was also an increase in unsaturation in the rhizenes at the highest growth temperature, with hexaenes dominant over the pentaenes but in the rhizenes, Z to E isomerisation increased. Increased salinity from 15 to 35 psu increased cell growth and rhizene production but decreased haslene production. Unsaturation in haslenes was not changed by increased salinity but unsaturation in the rhizenes decreased. These may reflect growth rate differences. The carbon isotopic compositions of the haslenes and rhizenes were similar to that of the major sterol at 18 degrees C, but the major HBI isomers were 3-4 per mil depleted relative to phytol released by saponification from chlorophyll a. This suggests biosynthesis of HBIs from a different isotopic pool of isopentenyl biphosphate to that from which phytol is biosynthesised. At 25 degrees C, further isotopic differences were observed. The variables controlling HBI distributions in R. setigera are still not fully understood and rationalisation of the environmental controls on the sedimentary distributions of the HBIs from R. setigera may only be possible once such factors are established.

Alkenes↗
PubMed2001

Neonatal thermal care, part I: Survey of temperature probe practices.

PURPOSE: To determine nurses' practices regarding skin temperature probes. DESIGN: Data were collected using an anonymous questionnaire, which was returned by mail. Questionnaires were distributed by volunteer neonatal nurses. Items included frequency of probe change, position of probe, use of probes in skin and air servocontrolled incubators and radiant warmers, as well as demographic data. SAMPLE: Eighty-three neonatal nurses. RESULTS: Nurses reported that skin servocontrolled incubators are used widely, but generally only for infants less than 28 weeks gestational age; a high proportion of respondents reported using continuous monitoring of skin temperature in air servocontrol incubators. Although most nurses reported positioning infants to prevent their lying on the probe, 21 percent reported using the same probe site regardless of infant position. Routine changing of the probe cover was reported by a number of nurses. Practices were influenced by individual knowledge, beliefs, and experience as well as by unit protocols, which varied widely.

Attitude of Health Personnel↗
PubMed2001

Neonatal thermal care, part II: Microbial growth under temperature probe covers.

PURPOSE: To determine if temperature probe covers contribute to nosocomial infections by providing an environment for skin microbe colonization. DESIGN: Descriptive, comparative design with infants randomized into two groups: foam probe cover and hydrogel probe cover. Skin cultures were obtained 72 hours after cover placement. Bacterial growth was quantified after 24 and 48 hours. Skin integrity was assessed using visual irritations scores (VIS) every 5 minutes for 30 minutes following cover removal. ANOVA and ANOVA-RM were used to compare amounts of microbes and VIS scores between groups. SAMPLE: Twenty-six medically stable infants, 29 to 34 weeks gestational age, less than 10 days postbirth, and in an incubator. MAIN OUTCOME VARIABLE: Microbial growth and VIS. RESULTS: There were no statistically significant differences in microbial growth and VIS scores between groups (p > .05). Clinical significance was noted in VIS scores. Infants who had foam covers had more sustained irritation scores.

Analysis of Variance↗
PubMed2001

Neonatal thermal care, part III: The effect of infant position and temperature probe placement.

PURPOSE: Accurate management of infant temperature requires appropriate placement of temperature monitoring probes. Currently, there is a lack of consensus regarding placement of skin temperature probes and the effect on temperature monitoring of the infant's lying on the probe. The objective of this study was to compare abdomen and back skin temperatures when infants were positioned supine and prone. DESIGN: A quasi-experimental design was used to randomize infants to prone or supine position. Infant back, abdomen, and axillary temperatures were measured at one-minute intervals with small disposable thermocouples over a one-hour period. SAMPLE: Twenty-three infants, weight 820-2,400 gm, gestational age 27-37 weeks, postnatal age three to ten days. MAIN OUTCOME VARIABLE: Gradient between abdomen and back temperature. RESULTS: Both mean abdomen and mean back temperatures differed significantly by position (t-test, p = .003 and .028, respectively). Weight and postnatal age did not have an effect on the mean difference between abdomen and back temperature. Results indicate that probe placement and infant positioning are important factors altering measurement of skin temperature.

Abdomen↗
PubMed2000

Internet resources for perinatal and neonatal nurses.

The goal of this column is to provide JPNN readers with a periodic update of additional Internet resources they may find useful for their practice, for recommending to clients and their families, or for teaching.

Humans↗
PubMed1999

Stereopsis based on monocular gaps: metrical encoding of depth and slant without matching contours.

It is often the case in binocular vision that one eye can see between two objects lying at different distances but the other eye cannot. We have found that the visual system is able to correctly interpret images produced this way in which a single solid rectangle in one eye is fused with two half-sized rectangles in the other eye separated by a vertical gap comprising the background. Two rectangles in depth are seen. It is as if the solid rectangle is treated as two components which each match one of the physically separated rectangles in the contralateral eye. The sign of the depth depends on which eye's view has the gap and its magnitude increases with gap width. Measured depth is found to be equivalent to real stereoscopic depth with a relative disparity equal to the monocular gap. If overall disparity differences are eliminated, between the left and the right images, variations in perceived slant of the two rectangles are still seen with increasing gap size. That two surfaces can be seen in metric binocular depth despite complete camouflage of their separation in one eye's view, suggests that stereopsis be regarded as a broad process of surface recovery not necessarily requiring image disparity at the location of the depth step.

Depth Perception↗
PubMed1999

Internet resources for neonatal nurses.

The availability of health information over the Internet has exploded in recent years. Nurses can use the Internet to access information to support professional and clinical interests and join in dialogues with colleagues around the world. The Internet can also be used to identify resources for clients and their families. As with any other information resource, Internet sites must be evaluated for accuracy, currency, and objectivity. The article describes examples of Internet resources and discussion forums for neonatal nurses, use of search engines to find and retrieve information about specific topics, and evaluation of World Wide Web sites.

Adult↗
PubMed1999

Dementia. Part 4: Risk management.

Negative assumptions that people with dementia are at risk from a variety of dangers often influence the care they receive. Such attitudes are usually based on misunderstandings about the meaning behind observed behaviours. Good risk management practice involves assessing how risk can be managed in ways that enhance autonomy and wellbeing.

Aged↗
PubMed1998

Environmental impact of the NICU on developmental outcomes.

The neonate, especially the premature one, is both dependent on and vulnerable to the intensive care environment to support physiologic and neurobehavioral organization. Concerns about this environment have led to suggestions that it may be a major contributing factor in the persistent incidence of behavioral and learning problems among preterm infants. By modifying the neonatal intensive care environment to provide a more developmentally supportive milieu, we can better meet the infant's physiologic and neurobehavioral needs, support the infant's emerging organization, and foster growth and development.

Developmental Disabilities↗
PubMed1995

Panum's limiting case: double fusion, convergence error, or 'da Vinci stereopsis'.

Panum's limiting case--a perceived depth difference between two lines in one eye combined with only one in the other eye--has long been considered weak or reversible. In the last few years this has led to strong promotion of the view that Panum's case is not based on a stereoscopic process involving double fusion, that only one line is fused, with the depth of the other one attributable either to fixation disparity or to occlusion cues. This view is refuted in two ways. First it is shown that when the separation of the two lines, considered as a disparity, is within the range of 'patent stereopsis', depth is perceived with a precision and accuracy indistinguishable from regular stereopsis. The predictions of nonstereoscopic theories concerning the effects of fixation are not borne out at small disparities. Second, very compelling Panum versions of orientation and curvature disparity are introduced, which are difficult to account for except by a process of double fusion. Finally it is shown that at large disparities the depth in Panum's case deviates from prediction more frequently than does regular stereoscopic depth.

Convergence, Ocular↗
PubMed1995

Problems of preterm infants after discharge.

Preterm infants often experience continuing health problems after discharge and have a higher rate of readmittance to the hospital during the first year. These infants also are at risk for neurodevelopmental problems, such as language, learning, and school difficulties. The continuing health and developmental problems of preterm infants creates stress for the family. Nurses caring for these infants in hospital settings must understand the problems for which preterm infants are at risk after discharge as a basis for appropriate discharge planning and teaching. A similar knowledge base will help nurses working in community settings in assessment and interventions with infants and their families after discharge.

Developmental Disabilities↗
PubMed1995

Hyperbilirubinemia and neonatal jaundice.

Jaundice is a common physiologic problem seen in both term and preterm infants. Normal transitional changes in bilirubin metabolism lead to physiological jaundice in many infants. In some infants these normal changes at birth may be exaggerated, such as occurs with immaturity, or may interact with health alterations (pathologic jaundice), resulting in the accumulation of excess bilirubin and development of hyperbilirubinemia. Caregivers must appreciate the processes and the basis for physiologic jaundice and hyperbilirubinemia and recognize infants at risk for these disorders. This article reviews neonatal bilirubin metabolism as a basis for understanding the causes and treatment of physiologic jaundice and hyperbilirubinemia arising from either physiologic or pathologic causes. Patterns of bilirubin in breast fed infants are discussed along with other issues related to breast feeding and jaundice. Treatment of hyperbilirubinemia and implications for nursing assessment and management of infants under phototherapy are also described.

Breast Feeding↗
PubMed1994

Interrater agreement for diagnosis of Alzheimer's disease: the MIRAGE study.

There are standardized criteria to assist in the diagnosis of Alzheimer's disease (AD), a disorder that lacks unique clinical, morphologic, or biochemical features. Diagnostic reliability of single groups of investigators using these criteria is moderate to substantial. In this study, seven clinicians at separate sites established a criteria-based diagnosis in 42 consecutive memory disorder patients participating in a national genetic epidemiologic study using a quantitative multiaxis AD rating scale (ADRS) that incorporates NINCDS/ADRDA criteria, reliability of information, and comorbidity. Reliability, measured by a generalized kappa statistic for more than two raters, was substantial (0.63 +/- 0.13) when the subjects were grouped as "AD" (probable or possible) versus "not AD," but somewhat lower (0.52 +/- 0.10) when subjects were classified as probable AD, possible AD, or not AD. There was unanimous agreement for two-thirds of the subjects using a dichotomous classification scheme. These findings suggest that the ADRS is a useful diagnostic instrument for multicenter studies.

Alzheimer Disease↗