The effect of mode of delivery on neonatal mortality in very low birthweight infants born in Victoria, Australia: Caesarean section is associated with increased survival in breech-presenting, but not vertex-presenting, infants

To determine whether the improved survival of very low birthweight (VLBW) infants (< 1500 g) born in Australia can be attributed to currently high rates of Caesarean section, we examined the associations between neonatal mortality and Caesarean section in singleton liveborn VLBW infants (500–1499 g) born during 1986–93 in Victoria, Australia, using data from the Victorian Perinatal Collection Unit. The infants included in this study had completed > 23 weeks of gestation, had no life-threatening malformations and had not been delivered by a repeat Caesarean without a trial of labour (n = 2763). For infants weighing 500–749 g, 750–999 g, 1000–1249 g and 1250–1499 g, the neonatal mortality rates were 56.1%, 25.7%, 13.0% and 4.3% respectively, and the Caesarean section rates were 33.1%, 42.3%, 54.8% and 55.8%. Nearly half of these births (n = 1269) were associated with one or more obstetric indications for Caesarean section (non-breech malpresentaion, fetal distress, prolapsed cord, placenta praevia, pre-eclampsia and hypertension). Overall, the odds ratio (OR) for neonatal death associated with Caesarean section was 0.92 [95% confidence interval 0.60–1.41], after adjustment for gestational age, birthweight, year of birth, type of hospital, presence or absence of labour, presentation and obstetric indications for Caesarean section. However, when the vertex-presenting (n = 1702) and breech-presenting (n = 746) infants were considered separately, the adjusted ORs for neonatal death were 1.98 [0.96–4.10] and 0.52 [0.29–0.96] respectively. For those infants without obstetric indications for Caesarean section, the adjusted ORs for neonatal death in vertex-presenting (n = 950) and breech-presenting (n = 446) infants were 3.80 [1.11–13.0] and 0.47 [0.23–0.6]. These recent population - based data support the view that Caesarean section does not enhance the neonatal survival of VLBW babies when obstetric complications are absent.     

Implosive therapy for the treatment of combat-related PTSD

Implosive therapy for the treatment of post-traumatic stress disorder is based on the principle of exposing the patient to trauma-related cues until there is a reduction in the anxiety associated with the cues. It is a relatively specialized procedure regarding which few clinicians receive extensive supervised training, despite the numerous case studies that demonstrate its effectiveness. The present paper addresses a number of procedural issues and offers guidelines for conducting implosive therapy with traumatized combat veterans. Elements of controversy regarding the application of implosive therapy are discussed.     

Effects of diflubenzuron on limb regeneration and molting in the fiddler crab, Uca pugilator

Fiddler crabs, Uca pugilator, were exposed to the insect growth regulator diflubenzuron (Dimilin^®) at 0.5, 5, and 50 μg/l after multiple autotomy of one chela and five walking legs. Regeneration of the first walking leg was monitored, and time to ecdysis, mortality, and morphology of the regenerated limbs observed. Continuous exposure to the chemical produced a dose-dependent retardation of regeneration. Animals molting in the higher concentrations exhibited significant mortality at ecdysis. Exposure to the pesticide for a single week produced similar but less severe effects. However, if crabs molted while in the pesticide, significant mortality was observed. The presence of sediment in the container with the crab moderated the effects of the pesticide, but did not eliminate them.

The regenerated limbs of the crabs that survived ecdysis were found to have lesions in the form of black areas in which the cuticle was improperly developed. These lesions were seen in crabs that had been in the pesticide for only one week (week 2 or week 3) as well as those that had had continuous exposure. They were also seen in crabs that regenerated in Dimilin with sediment. In addition, the number of setae on limbs was reduced compared to the number on limbs that had regenerated in clean sea water.     

Neuron-specific enolase and malignant lymphomas (23 cases)

Summary The immunoreactivity of polyclonal antiserum to neuron-specific enolase (NSE) has been investigated. Twenty-three cases of malignant lymphoma (ML) were studied and compared with previously published reports. In our study 11 out of 23 cases showed strong or weak NSE positivity; any type of ML could be positive or negative even among B or T cell ML. This study indicated that polyclonal NSE is not a specific marker; it might be an inconstant marker of ML with no apparent correlation between reactivity and morphology or phenotype.     

Sample size considerations when groups are the appropriate unit of analysis.

This article discusses issues to be considered by nurse researchers when groups should be used as the unit of randomization. Advantages and disadvantages are presented, with statistical calculations needed to determine the effective sample size. Examples of these concepts are presented using data from the Black Cosmetologists Promoting Health Program. Different hypothetical scenarios and their impact on sample size are also presented. Given the complexity of calculating the sample size when using groups as the unit of randomization, it is advantageous for researchers to work closely with statisticians when designing and implementing studies that anticipate the use of groups as the unit of randomization.     

Survival Strategies for Nurse-Midwifery Students

Nurse-midwifery students face multiple stressors in their educational experience. Strategies to resolve stress and promote adaptation to the new role are examined and measures used to promote students' adaptation to the educational experience are described.     

The effects of increased physical exercise on disruptive behavior in retarded persons

The low frequency but highly intense disruptive behavior of 10 institutionalized mentally retarded persons was treated by providing them with opportunities for vigorous exercise. In two experiments, severely aggressive and hyperactive clients were exposed to two daily periods of jogging and strenuous activities in multiple baseline designs across clients. Rating scale data collected daily from cottage and school personnel indicated a systematic reduction in problem behavior for 8 of the 10 participants to levels considered "not a problem" or only "an occasional problem." Physical exercise may offer promise as an effective, benign, and practical adjunct to other treatment and management techniques.     

Cytogenetic effects of methylmercury in embryos of the killifish,Fundulus heteroclitus

Fertilized eggs of the killifish,Fundulus heteroclitus, were exposed experimentally to methylmercury (MeHg) to evaluate whether this compound induced cytogenetic effects expressed in the embryos. An additional objective was to assess cytogenetically whetherFundulus embryos from groups that were determined to be more susceptible to the teratogenic effects of MeHg were also more susceptible to its mutagenic effects. Embryos exposed to 0.05 mg/L MeHg for 1 and 7 days post-fertilization were preserved in 10% formalin for cytological examination, while unfixed embryos from the same clutches were evaluated for teratogenic effects. Untreated embyros from each clutch served as controls. Cytogenetic-cytological analyses of fixed treated susceptible embryos that exhibited teratogenic effects revealed decreased mitotic counts (5.0-fold), and increased chromosomal aberrations (2.5-fold) when compared to their controls. There were also decreased mitotic counts (1.5-fold) and increased chromosomal aberrations (2-fold) in embryos from resistant groups when compared to their controls. Exposure to MeHg also retarded development. Forty to fifty percent of the susceptible and resistant control embryos reached the tail-bud stage, but only 28% of the treated resistant and none of the treated susceptible embryos reached this stage. There was also a significant correlation (P < 0.05) between teratogenic and mutagenic effects of MeHg in early stages ofFundulus.