An unusual hernia: congenital pericardial effusion associated with liver herniation into the pericardial sac

To our knowledge there have been only two previous cases of diaphragmatic hernia into the pericardium diagnosed antenatally. We describe our pre- and post-natal radiological findings in such a case, although the final diagnosis eluded us until after delivery.     

Double dissociation between the involvement of the bed nucleus of the stria terminalis and the central nucleus of the amygdala in startle increases produced by conditioned versus unconditioned fear

The amplitude of the acoustic startle response is reliably enhanced when elicited in the presence of bright light (light-enhanced startle) or in the presence of cues previously paired with shock (fear-potentiated startle). Light-enhanced startle appears to reflect an unconditioned response to an anxiogenic stimulus, whereas fear-potentiated startle reflects a conditioned response to a fear-eliciting stimulus. We examine the involvement of the basolateral nucleus of the amygdala, the central nucleus of the amygdala, and the bed nucleus of the stria terminalis in both phenomena. Immediately before light-enhanced or fear-potentiated startle testing, rats received intracranial infusions of the AMPA receptor antagonist 2, 3-dihydroxy-6-nitro-7-sulphamoylbenzo(F)-quinoxaline (3 microg) or PBS. Infusions into the central nucleus of the amygdala blocked fear-potentiated but not light-enhanced startle, and infusions into the bed nucleus of the stria terminalis blocked light-enhanced but not fear-potentiated startle. Infusions into the basolateral amygdala disrupted both phenomena. These findings indicate that the neuroanatomical substrates of fear-potentiated and light-enhanced startle, and perhaps more generally of conditioned and unconditioned fear, may be anatomically dissociated.     

Factors that influence the use and perceptions of employee assistance programs at six worksites

Employee assistance programs (EAPs) have gained significant importance in contemporary worksites. This article uses data from 6 case studies to examine several research questions regarding the relationship between worker demographic (e.g., gender, job tenure, and marital status), substance use, and workplace policies and the actual and potential use of the company EAP. Unlike in most of the existing literature, the authors did not find that gender, marital status, or job dissatisfaction are statistically related to actual or potential EAP use at most worksites. However, job tenure and some substance use behaviors were related to actual EAP use in a positive and statistically significant way. Another important finding, underlying the credible integration of EAPs into worksite culture, is the positive and robust relationship between employee trust and confidence in the EAP and actual use. The results of our study both reinforce some long-established principles in the EAP field and encourage further consideration of other beliefs.     

An algorithm for computing the inverse Z transform

The authors determine an infinite impulse response of a causal system via a sampling algorithm applied to the transform on the unit circle     

Predicting high-risk preterm birth using artificial neural networks.

A reengineered approach to the early prediction of preterm birth is presented as a complimentary technique to the current procedure of using costly and invasive clinical testing on high-risk maternal populations. Artificial neural networks (ANNs) are employed as a screening tool for preterm birth on a heterogeneous maternal population; risk estimations use obstetrical variables available to physicians before 23 weeks gestation. The objective was to assess if ANNs have a potential use in obstetrical outcome estimations in low-risk maternal populations. The back-propagation feedforward ANN was trained and tested on cases with eight input variables describing the patient's obstetrical history; the output variables were: 1) preterm birth; 2) high-risk preterm birth; and 3) a refined high-risk preterm birth outcome excluding all cases where resuscitation was delivered in the form of free flow oxygen. Artificial training sets were created to increase the distribution of the underrepresented class to 20%. Training on the refined high-risk preterm birth model increased the network's sensitivity to 54.8%, compared to just over 20% for the nonartificially distributed preterm birth model.     

Parametric modulation of an atomic magnetometer

The authors report on a rubidium atomic magnetometer designed for use in a shielded environment. Operating in the spin-exchange relaxation-free regime, the magnetometer utilizes parametric modulation of the z-magnetic field to suppress noise associated with airflow through the oven and to simultaneously detect x- and y-field components, using a single probe beam, with minimal loss of sensitivity and bandwidth. A white noise level of 60 fT/(Hz)(1/2) was achieved.     

Clinical evaluation of Acuvue contact lenses with UV blocking characteristics

BACKGROUND: In response to increasing scientific evidence which indicates that ultraviolet radiation (UVR) is a potential threat to ocular health, Acuvue contact lenses (Vistakon, Johnson & Johnson Vision Products Inc., Jacksonville, Florida) have been developed which incorporate an ultraviolet (UV) blocker within the lens polymer. Data are presented for the first clinical evaluation of Acuvue lenses with UV blocking characteristics. METHOD: A double-masked, multicenter, prospective clinical trial involving 94 subjects was conducted. The study followed a randomized, parallel group design and consisted of 3 months of daily wear with two-weekly lens replacement. Two thirds of the subjects (61) wore the test lenses (Acuvue with UV blocker) and the remaining subjects (33) wore conventional Acuvue lenses (without UV blocker). RESULTS: Biomicroscopic evaluations indicated that the performance of the test and control lenses was clinically similar. No clinically relevant differences between the test and control lenses were noted in the subjective assessments of vision, comfort, or handling. In addition, no differences were shown for surface deposition, lens durability, visual acuity, and subjective symptoms. CONCLUSION: The study findings indicate that the addition of a UV blocker to Acuvue contact lenses has been achieved without affecting daily wear clinical performance. Because there is increasing evidence to suggest that the ocular tissues may be damaged by UVR, it is prudent for eye care practitioners to prescribe contact lenses that offer the benefits of both regular replacement and UV protection.     

Thoracic spinal neuron responses to repeated myocardial ischemia and epicardial bradykinin

Bradykinin has been strongly implicated as a mediator of cardiac nociception. During coronary artery occlusion, the content of bradykinin in coronary sinus blood increases. In non-cardiac tissues nociception to bradykinin exhibits tachyphylaxis, however, this phenomenon has not been rigorously studied in the heart. This raises the question that repeated coronary occlusions may also result in tachyphylaxis, thereby reducing cardiac sensation on subsequent ischemic stimulation. We therefore examined the hypothesis that repetitive episodes of myocardial ischemia and of epicardial application of bradykinin demonstrate tachyphylaxis. Mongrel cats were anesthetized with alpha-chloralose and heart rate, arterial pressure, and thoracic spinal neuron firing rate were recorded during 60 s of anterior descending coronary occlusion or local epicardial application of bradykinin (10 microM). Neurons were identified by cutaneous receptive fields in the left shoulder area. Sixty-one of 93 neurons tested responded with an increase in firing rate to coronary artery occlusion only (n=24), bradykinin only (n=19) or to both (n=18). On repetitive coronary occlusion, 14 of 25 neurons demonstrated tachyphylaxis compared to 12 of 15 tested with bradykinin (p<0.05). Similar responses were observed in thoracic spinal neurons that projected to the brain. In neurons demonstrating tachyphylaxis, dorsal cervical cold block partially restored the neuronal activation to coronary occlusion but not to bradykinin. We conclude, based on neuronal responses to repetitive stimuli, that afferent spinal responses to coronary occlusion and bradykinin are different. These data suggest that bradykinin is not the sole mediator of myocardial ischemic pain. The tachyphylaxis to repeated coronary artery occlusions may contribute to the clinical phenomenon of silent myocardial ischemia.     

Contribution of parental blood pressures to association between low birth weight and adult high blood pressure: cross sectional study

OBJECTIVE: To examine the possibility that low birth weight is a feature of the inherited predisposition to high blood pressure. DESIGN: Cross sectional study. SETTING: Primary care medical centre in Edinburgh. SUBJECTS: One offspring of 452 families (231 men and 221 women aged 16-26 years) in whom blood pressure, weight, and height were measured in 1986 and whose parents had blood pressure measured in 1979. Birth weights were obtained from case records (270 offspring) or by questionnaires sent to the mothers (182 offspring). MAIN OUTCOME MEASURES: Birth weight and adult systolic blood pressure in offspring in relation to parental blood pressure. RESULTS: If parental blood pressures were not considered, a 1 kg decrease in birth weight was associated with a 2.24 mm Hg increase in systolic blood pressure of offspring (P = 0.06) after correction for current weight and sex. However, parental blood pressures correlated positively with blood pressure of offspring, and higher maternal blood pressure was associated with lower birth weight (-3.03 g/mm Hg, P < 0.01). After correction for parental blood pressures, a 1 kg decrease in birth weight was associated with only a 1.71 mm Hg increase in the systolic blood pressure of the offspring (P = 0.15). CONCLUSIONS: Low birth weight is a feature of the inherited predisposition to hypertension, perhaps because it is associated with higher maternal blood pressure during pregnancy. Parental blood pressure may be an important confounding factor in the relation between low birth weight and subsequent hypertension.