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Biomedical subjects

B A Collins

Publications and source records attributed to B A Collins.

At least 19 recordsLinked to original sources
PubMed1996

The preterm prediction study: maternal stress is associated with spontaneous preterm birth at less than thirty-five weeks' gestation. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

OBJECTIVE: Our purpose was to determine whether various measures of poor psychosocial status in pregnancy are associated with spontaneous preterm birth, fetal growth restriction, or low birth weight. STUDY DESIGN: Anxiety, stress, self-esteem, mastery, and depression were assessed at 25 to 29 weeks in 2593 gravid women by use of a 28-item Likert scale. Scores for each psychosocial subscale were determined, and an overall psychosocial score was calculated. Scores were divided into quartiles, and the lowest quartile scores were used to define poor psychosocial status. The percent spontaneous preterm birth, low birth weight, and fetal growth restriction in women with low and high psychosocial scores were compared. Logistic regression analyses provided the odds ratios and 95% confidence intervals. RESULTS: Analyses revealed that stress was significantly associated with spontaneous preterm birth and with low birth weight with odds ratios of 1.16, p = 0.003, and 1.08, p = 0.02, respectively, for each point on the scale. A low score on the combined scale or on any subscale other than stress did not predict spontaneous preterm birth, fetal growth restriction, or low birth weight. After multivariate adjustment was performed for psychosocial status, substance use, and demographic traits, black race was the only variable significantly associated with spontaneous preterm birth, fetal growth restriction, and low birth weight; stress and low education were associated with spontaneous preterm birth and low birth weight. CONCLUSION: Stress was associated with spontaneous preterm birth and low birth weight even after adjustment for maternal demographic and behavioral characteristics. Black race continues to be a significant predictor of spontaneous preterm birth, fetal growth restriction, and low birth weight even after adjustment for stress, substance use, and other demographic factors.

Adult↗
PubMed1996

The nursing management of women experiencing preterm labor: clinical guidelines and why they are needed.

Nursing care is a critical component of therapy for women experiencing preterm labor. Diversity exists, however, in the level of comprehensiveness and consistency in guidelines for clinical practice. Nonstandardized care interferes with the ability to achieve consistent, positive patient care outcomes. This article is intended for nurses who seek to organize and standardize their care for women experiencing preterm labor. This article presents a review of the applicable practice and research literature. Clinical guidelines for the nursing management of women experiencing preterm labor are presented in the appendix.

Female↗
PubMed1994

Descriptions of comfort by substance-using and nonusing postpartum women.

OBJECTIVE: To compare definitions of comfort held by a group of postpartum substance users with those of a group of nonusers. SETTING: The postpartum unit of a large university hospital. PARTICIPANTS: The convenience sample constituted 36 postpartum women; half were substance users and half denied substance use. The nonusing participants were matched to the users according to age, race, type of delivery, and parity. DESIGN: Qualitative, descriptive. MAIN OUTCOME MEASURES: Data were collected through semistructured, individual interviews. Patients defined comfort and described the characteristics and patterns of comfort during the postpartum period. RESULTS: Data were analyzed into three categories of themes. Attributes of comfort were resolution of pain, resolution of fatigue, satiation of hunger, resolution of individual irritants, and relaxation. Interventions for comfort were standard therapy, supportive presence, and caring nursing approach. Modifiers of comfort were individualized comfort patterns, environmental ease, and maternal concern. CONCLUSIONS: Comfort is more than the absence of pain. A supportive presence and a caring nursing approach were the most helpful interventions.

Adolescent↗
PubMed1993

Injuries to pedal cyclists resulting in death and hospitalisation.

AIM: To determine the incidence of injury deaths and hospitalisations associated with pedal cycle use in both traffic and nontraffic environments and in the national population of New Zealand. METHODS: All cases of pedal cycle injuries resulting in death between 1979-88, and all those resulting in hospitalisation in 1988 were identified from health information services files. RESULTS: Between 1979 and 1988, 238 cyclists died. Seventy-six percent were male, and 39% of all fatalities occurred to those aged 5-14 years. Collisions with motor vehicles accounted for most fatalities. Head injuries alone, or with other injuries, were associated with death in 60% of cases. In 1988, 1500 cyclists were admitted to hospital for the treatment of their injuries. Fifty-one percent of those hospitalised were aged 5-14, and males accounted for 70% of all admissions. Thirty-four percent involved a collision with a motor vehicle. Intracranial injuries and skull fractures accounted for 46% of hospital admissions, and had the highest scores on the abbreviated injury scale (AIS). CONCLUSION: This study shows that head injuries are a common cause of death and hospital admission for cyclists. Increases in cycle helmet wearing rates are likely to reduce the frequency and severity of head injury. Other prevention strategies include cycling skills programmes that have been evaluated and shown to be effective, the identification and modification of aspects of cycle design that contribute to injuries, and changes to road design.

Abbreviated Injury Scale↗
PubMed1993

Ethical issues in conducting clinical nursing research.

It frequently is assumed that research is being conducted in an ethical manner. Although this usually is the case, the approaches used to assure an ethical approach are not explicitly described in research proposals, protocols, presentations, or manuscripts. This paper explicates the ethical issues related to conducting clinical nursing research. Ethical principles and the problems of scientific misconduct are presented. Rights of human subjects and rights of special subjects are discussed, and practical points about the conduct of ethical research are summarized.

Animal Welfare↗
PubMed1992

Calcium signalling in single growth hormone-releasing factor-responsive pituitary cells.

The release of pituitary GH appears to be critically dependent on alterations in the free intracellular Ca2+ concentration ([Ca2+]i). However, little is known about the nature of Ca2+ signalling within normal pituitary cells. We, therefore, examined [Ca2+]i patterns in individual cultured pituicytes of adult male rats under basal conditions and in response to GH regulatory agents, using the calcium-sensitive dye fura-2 together with digital imaging microscopy. Perfusion of cultured anterior pituitary cells with GH-releasing factor (GHRF) resulted in a marked increase in [Ca2+]i in specific pituitary cells. These cells did not respond to other hypothalamic secretagogues (GnRH, TRH, or CRF), and there was no evidence of desensitization on repetitive administration of GHRF. Somatotrophs (n = 134) exhibited spontaneous oscillations of [Ca2+]i in the basal state, with considerable heterogeneity of oscillatory patterns among cells. After application of a near-maximal stimulatory dose of GHRF (1 nM), there was a striking 2.2-fold increase in the amplitude of [Ca2+]i oscillations and only a modest increase in their frequency. Forskolin (1 microM) augmented somatotroph [Ca2+]i in patterns similar to those of GHRF. Somatostatin (10 nM) abolished the [Ca2+]i response to GHRF (n = 26); this reflected a marked reduction in the amplitude of [Ca2+]i oscillations and a slight reduction in their frequency. Ca(2+)-free medium or the Ca2+ channel antagonist nimodipine (0.1-1 microM) suppressed the Ca2+ stimulatory effect of GHRF. Conversely, the Ca2+ channel agonist BAY K8644 (1 microM) strikingly augmented the GHRF-induced rise in [Ca2+]i, with a major stimulatory effect on the amplitude of [Ca2+]i oscillations and no observed effect on their frequency. In summary, GHRF and other hypothalamic secretagogues increase [Ca2+]i in pituitary cells in a highly specific manner, consistent with the known specificity of their effects on hormone release. Somatotrophs exhibit spontaneous rhythmic oscillation of [Ca2+]i in the basal state. Known regulators of GH release markedly alter the [Ca2+]i oscillatory pattern in characteristic manners, exerting predominant effects on the amplitude of [Ca2+]i pulses and lesser effects on their frequency. These striking effects of GH regulatory agents on pituitary Ca2+ signalling are consistent with the concept that modulation of [Ca2+]i is a critical mediator of somatotroph function.

Animals↗
PubMed1989

The antagonism by BW A868C of PGD2 and BW245C activation of human platelet adenylate cyclase.

1. In glycerol-lysed human platelets, prostaglandin D2 (PGD2) and the hydantoin BW245C both activate adenylate cyclase in a biphasic manner. These activations are qualitatively different from those of carbacyclin, iloprost and prostaglandin E2 (PGE2) whose E/[A] curves can be adequately described by rectangular hyperbolae. 2. Prostaglandin E1 (PGE1) had E/[A] curves of slope significantly lower than that expected for a rectangular hyperbolae. 2. Prostaglandin E1 (PGE1) had E/[A] curves of slope significantly lower than that expected for a rectangular hyperbola. 3. The selective PGD2 antagonist BW A868C shifts the first phase of the PGD2 and BW245C E/[A] curves but has no effect on the second phase. 4. Applying a two-receptor model enables a pKB to be derived for BW A868C of 9.11. 5. BW A868C has no effect on carbacyclin, iloprost, prostacyclin, PGE1 and PGE2 at a concentration 1,000 fold that of its KB against PGD2 and BW245C. 6. These results indicate that PGD2 and BW245C are capable of activating adenylate cyclase in human platelets through the DP-receptor and by another mechanism as yet uncharacterized.

Adenylyl Cyclases↗
PubMed1989

Do you need an external consultant? A model for decision making.

Consultation is an integral part of the clinical nurse specialist (CNS) role. Some problems, however, are best resolved by a consultant from outside of the organization. This paper presents a decision-making model for use by CNSs in determining the need for an external consultant. The decision-making model involves two general steps. Each step introduces a series of incumbent questions. In the first step, the nature of the problem is assessed, and questions about the philosophical foundation, theoretical framework, and problem substruction are introduced. In the second step, the requirements for solution of the problem are described, precipitating questions about the consultant role requirements, role functions, and introspection and evaluation. Through systematic questioning about the nature of the problem and the solution requirements, the CNS may make an informed decision regarding the recommendation to employ an external consultant. An overall blueprint for the systematic questioning in this decision-making process is presented.

Attitude↗
PubMed1984

Blue-sensitive cones in the primate retina: microspectrophotometry of the visual pigment.

Direct absorbance and bleaching absorbance-difference spectra were obtained using a photon-counting microspectrophotometer from the outer segments of ten blue-sensitive cones of macaque monkeys. The peak wavelength (lambda max) of the direct measurements was 426 +/- 3.4 nm, whereas the lambda max of the bleaching difference was 434 +/- 6.6 nm. We consider these values to be upper and lower bounds since both measurements may be shifted in opposite directions by wavelength-dependent effects. Therefore, the true peak sensitivity must be close to 430 nm.

Animals↗
PubMed1979

Intraretinal distribution of cone pigments in certain teleost fishes.

Microspectrophotometric investigations of visual pigments in the teleost family Cichlidae determined that morphological "twin cones" need not be "pigment twins" as well. In each species there were two pigments that could be found in these cells; a "longwave" and a "shortwave" type whose precise spectral location varies for each species, making the terms red and green inadequate to describe them. Studies of the receptor mosaic with the nitro-blue tetrazolium chloride reduction technique permitted the sampling of larger receptor populations and confirmed that twin cones in several cichlid species could be either longwave-longwave, longwave-shortwave, or shortwave-shortwave pairs, and that the relative proportions of these twin cone types vary in different parts of the retinas. Nonuniform distribution of pigment types was also evident in the eyes of several other species from a variety of piscine taxa.

Animals↗
PubMed1979

Triple cones found in retinas of 3 fish species.

Triple cones were found in the retinas of 3 species of fishes indigenous to the Woods Hole area. The function of these triple cones can not be deduced from the behavior patterns of these fishes.

Animals↗
PubMed1979

Sectioning of Epon blocks in the 20 m to 60 micromicron range for histological studies.

Thick sections of tissue, (20 micron--60 micron), are useful in studying the relationship between individual large cells and cell layers in organized neural structures. The ability of the Nomarski Differential Interference-Contrast Microscope to bring a single thin layer into sharp focus makes the examination of such sections feasible. Although celloidin is the classical embedding medium for large, thick sections of neural tissue, the time necessary for this preparation is most inconvenient. Epon is an excellent embedding medium; however, it is extremely hard and brittle. By heating the Epon block face, thick sections can be cut. To avoid the cumbersome, often detrimental use of heat, a modification of this technique was found. Epon blocks, trimmed to a 1 millimeter square face, may be sectioned at room temperature on the sliding microtome at 20 micron to 60 micron with ease. The simple method of preparing such sections is described.

Animals↗
PubMed1978

Ellipsosomes: organelles containing a cytochrome-like pigment in the retinal cones of certain fishes.

Ellipsosomes are dense spherical bodies containing a very large concentration of a heme pigment spectroscopically resembling pure cytochrome c. They are located at the outer ends of the inner segments of the cones of certain fishes. Although, superficially, they resemble the similarly located oil droplets in the cones of birds and reptiles, their ultrastructure and staining properties resemble those of the neighboring mitochondria. However, like the oil droplets, they may serve as intracellular color filters.

Animals↗
PubMed1978

Long term fixation for histological studies.

It was found that a glutaraldehyde-formalin-phosphate buffered fixative could preserve retinal tissue for light microscopy, even if the tissue remained in the fixative for a month. Retinal tissue that previously was difficult and expensive to procure could now be obtained.

Animals↗