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Biomedical subjects

B J Snell

Publications and source records attributed to B J Snell.

10 recordsLinked to original sources
PubMed2000

Characterisation of central adenosine A(1) receptors and adenosine transporters in mice lacking the adenosine A(2a) receptor.

The present study was designed to assess whether adenosine A(2a) receptor knockout mice exhibit altered purine utilisation in brain nuclei. Specifically, the properties of adenosine transporters and adenosine A(1) receptors were characterised in brain membranes and on slide-mounted sections. The B(MAX) for [(3)H]nitrobenzylthioinosine ([(3)H]NBTI) binding (adenosine transporter density) was significantly reduced in brainstem membranes of homozygotes (560+/-52 fmol/mg protein, n=5, P<0.05, Kruskal-Wallis ANOVA) compared to wildtype (1239+/-213 fmol/mg protein) and heterozygous mice (1300+/-558 fmol/mg protein). Quantitative autoradiography data indicated that [(3)H]NBTI binding in the medulla oblongata of heterozygous mice was seen to decrease significantly (P<0.05) in the subpostremal nucleus tractus solitarius (NTS), medial NTS, inferior olive and area postrema (AP). On the other hand, in the homozygous mice a decrease was seen in the medial NTS and AP. In the pons, [(3)H]1, 3-dipropyl-8-cyclopentylxanthine ([(3)H]DPCPX) (adenosine A(1) receptor density) binding increased significantly (P<0.05, Kruskal-Wallis ANOVA) in the lateral parabrachial nucleus, caudal pontine reticular nucleus and locus coeruleus of homozygotes compared to wildtype. In higher brain centres, [(3)H]NBTI binding was reduced in the paraventricular thalamic nucleus of both heterozygous and homozygous mice, whereas [(3)H]DPCPX binding was reduced in the hippocampus and lateral hypothalamus of heterozygotes. In homozygotes, [(3)H]DPCPX binding in the hippocampus increased compared to wildtype mice. The present study indicates that deletion of the A(2a) receptor may have contributed to region-specific compensatory changes in purine utilisation in brain nuclei associated with autonomic, neuroendocrine and behavioural regulation.

Affinity Labels↗
PubMed2000

Visualisation of AMPA binding sites in the brain of mice lacking the adenosine A(2a) receptor.

Adenosine A(2a) receptor knockout mice (A(2a)R k/o) have been characterised as hypertensive, aggressive, anxious and hypoalgesic [12]. Thus, the present study was designed to investigate markers of glutamatergic transmission in specific brain nuclei associated with autonomic regulation. Visualisation of alpha-amino-3-hydroxy-5-methylisoxasole-4-propionic acid binding sites in the brains of A(2a)R k/o mice was achieved by utilising quantitative receptor autoradiography with (S)-[(3)H]-5-fluorowillardiine ([(3)H]FW:10 nM) on slide-mounted sections of mouse-brain. [(3)H]FW binding significantly increased in the nucleus tractus solitarius and area postrema of A(2a)R k/o mice compared with wildtype CD-1 mice. In other autonomic nuclei examined, binding was unchanged between wildtype and knockout mice. The present study suggests that glutamatergic neurotransmission within certain neural pathways involved in autonomic and motor control is altered in the brains of A(2a)R k/o mice.

Animals↗
PubMed1995

Development and experience of a university-based, freestanding birthing center.

OBJECTIVE: To describe our experience with a freestanding birthing center established in conjunction with a university medical center, and to determine the safety and effectiveness of such a program. METHODS: The University of California Irvine Medical Center opened a freestanding birthing center 2 miles from the hospital. The unit provides prenatal, labor, delivery, postpartum and well-baby care 24 hours/day. All direct patient care is provided by certified nurse-midwives. Data were collected prospectively to provide a descriptive account and to evaluate maternal and perinatal morbidity and mortality to determine the safety and efficacy of this approach. RESULTS: During the first 20 months of operation, the University of California Irvine Birthing Center cared for 1830 patients. Approximately 90% were indigent, 85% were Hispanic, and 35% were nulliparas. Of the total patients, 12% were transferred antenatally for high-risk conditions and 19% were transferred intrapartum. The cesarean rate for all patients was 10% (6.5% for those whose intrapartum care began at the birthing center). The perinatal mortality rate was six per 1000. Neonatal morbidity rates, neonatal intensive care unit admissions, and maternal complications were not greater than expected. CONCLUSION: The first 20 months of experience with a university-based, freestanding birthing center suggests that this alternative is safe for delivering obstetric and newborn care to low-risk patients.

Adolescent↗
PubMed1992

The association of formula samples given at hospital discharge with the early duration of breastfeeding.

Conflicting results have been reported regarding the association of formula samples given at hospital discharge with breastfeeding duration. This study investigated the relationship between the distribution of formula samples and breastfeeding duration in low-income Hispanic women. A gift pack of formula was distributed randomly to 88 breastfeeding women. All women received a telephone call at one and three weeks to collect information about infant feeding. Chi-square analysis revealed no significant difference in the proportion of women exclusively breastfeeding at one week. However, fewer women were exclusively breastfeeding in the gift pack group at three weeks (p less than .004). Gift packs given to Hispanic breastfeeding women are associated with a decrease in exclusively breastfeeding during the first three weeks postpartum.

Academic Medical Centers↗
PubMedDate not supplied

Use of prostaglandins for induction of labor.

Nurse-midwives are sometimes required to intervene in the normal process of labor. Numerous clinical trials have investigated the use of prostaglandins for induction of labor. Research indicates the use of prostaglandins to be a safe and effective method of induction of labor with favorable results when compared with the more traditional use of oxytocin. Patient acceptance appears to be favorable because of the reduced need for restrictive and invasive methods of monitoring and administration that accompany intravenous oxytocin. Thus, the use of prostaglandins for induction of labor offers nurse-midwives an attractive alternative to the use of oxytocin when induction is medically indicated. This article provides a description of the biochemical effects of prostaglandins on the uterus and cervix, development and clinical use of prostaglandin preparations, indications for use of induction, and potential for utilization in nurse-midwifery practice.

Birthing Centers↗
PubMedDate not supplied

The use of amnioinfusion in nurse-midwifery practice.

Intrapartum amnioinfusion is being used in a variety of clinical settings and for multiple therapeutic modalities to prevent fetal distress and improve outcomes. The procedure has demonstrated efficacy in cases of variable decelerations and thick, meconium-stained amniotic fluid. Amnioinfusion has been shown to improve maternal and neonatal outcomes by decreasing cesarean sections for fetal distress, improving cord pH, and decreasing the amount of meconium present below the cords at delivery. This article describes the pathophysiology of amniotic fluid volume disorders that indicate the use of amnioinfusion, reviews the literature regarding the indications and therapeutic effects, and describes techniques for the use of amnioinfusion. In addition, there is a discussion of the contraindications associated with the use of amnioinfusion and its use in and out of hospital settings. The technique for amnioinfusion is simple, easy, and inexpensive to initiate. It can be performed in a variety of settings, provided there is adequate equipment, personnel, and emergency services available. Certified nurse-midwives should become familiar and comfortable with the procedure in order to provide complete care for the families they serve.

Amnion↗
PubMedDate not supplied

Transfer rates from freestanding birth centers. A comparison with the National Birth Center Study.

This article reviews retrospective data derived from Sharp The BirthPlace. San Diego for 1993-94 and from the University of California. Irvine, Birthing Center for 1994 and compares these findings to data obtained from the National Birth Center Study (NBCS). The focus of this article is on intrapartum transfer rates from the two freestanding birth centers as a critical clinical indicator. Cause-specific transfer rates were calculated for eight clinical conditions. Data suggest that cause-specific intrapartum transfer rates are influenced by factors such as risk profile of the client population, distance to the referral center and mechanisms of transfer, definitions and diagnostic criteria used, and clinical practice guidelines. Reports from the literature, such as NBCS data, might serve as points of reference, but are likely not appropriate baseline indicators (benchmarks of "best practice") for clinical events, against which individual performance can be measured; rather, these benchmarks should be individually defined, based on characteristics unique to each birth center.

Birthing Centers↗
PubMedDate not supplied

Issues related to the practice of prescribing.

Prescribing a drug is intended to bring about a desired beneficial change in the health of an individual and has been practiced for centuries. The historical development, controls and regulations, and trends and issues in prescribing are provided to give nurses a strong foundation for practice. In almost all states, prescriptive authority has been expanded to include advanced practice nurses. An awareness of federal and state statutes and regulations can help nurses administer drugs in a safe, effective, and timely manner.

Drug Approval↗