An electron microscope study of synaptic contacts in the abdominal ganglion of Aplysia californica.

The fine structure of the abdominal ganglion of Aplysia californica has been studied in preparations fixed by immersion in aldehydes, either directly or after a survival of a few hours in artificial sea water. The central core of neuropil is surrounded by a rind of neuronal cell bodies floating in a subcapsular space containing a loose meshwork of neuronal and glial processes, separated by wide extracellular spaces. Large primary processes with deeply infolded membranes leave the neuronal perikarya and enter the neuropil where they branch into smaller processes containing either neurofilaments, neurotubules or both. Some have the appearance of initial segments. The neuropil is not a homogeneous structure. Rather, four types of zones can be distinguished: (1) zones of fibers of passage coursing together in the neuropil and making few synaptic contacts: (2) zones of neurosecretory fibers containing large granules and dense-core vesicles, again making few synaptic contacts: (3) zones with a great variety of synaptic contacts between medium size and small profiles; and (4) glomerular zones. The differentiated membranes of the synapses are characterized by a slight increase in density and by being regularly parallel to each other. Presynaptic densities are sometimes quite prominent but specialized dense cytoplasmic opacities have never been seen bordering the postsynaptic membranes, i.e., all synapses are of the symmetrical type. Interlemmal opacities vary considerably in density. In zone 3, the synaptic vesicles are of several sizes, are round, oval or flat, and are either clear or filled with different types of dense material. The population of vesicles within a single profile may consist either of a homogeneous group of similar vesicles or of various mixtures of two or three kinds of vesicles. In profiles with mixtures of clear and large dense-core vesicles, it is often only the clear vesicles which agglomerate towards the differentiated membranes. In such cases the large dense-core vesicles lie as a peripheral halo around the clear vesicles. Here, and especially in other large neuronal profiles not forming contact in the plane of section, they can be seen to associate specifically with mitochondria and glycogen. It is proposed that they do not contain neurotransmitters but are related to mitochondrial activities such as the storage of ATP or the movement of calcium ions. In profiles with mixtures of clear and small dense-core vesicles, both types of vesicles often touch the presynaptic membrane, suggesting the release of two transmitters or of a modulator or neurohormone with a transmitter, by a single terminal. Serial synapses are present in this zone. The glomerular zones contain small profiles forming many synaptic contacts, some of which are arranged in such a way as to suggest the existence of "reciprocal" serial synapses.     

Précipitation et prévention de l'abstinence chez le rat et la souris en état de dépendance aiguë. Comparaison de la naloxone,de la naltrexone et de la diprenorphine

Summary Abstinence signs were precipitated in rats by naloxone (1 mg·kg^-1 s.c.) injected at various times (from 1.5 to 16 h) after a single dose of morphine hydrochloride (15 or 50 mg·kg^-1 s.c.) administered incaqueous solution. Increasing the dose of morphine increased the latency of the phenomena and the duration of the underlying state shifts of signs as described by Bläsig et al. (1974) in chronically morphinized rats also occurred when increasing the dose of morphine and the time interval between the injections of morphine and of naloxone. Naltrexone and diprenorphine were also effective. These three antagonists, given before morphine, were able to prevent precipitated abstinence: however, naloxone was almost ineffective when the higher dose of morphine was used and when the time interval was long. In these latter conditions, naltrexone was definitely more effective and longer acting and diprenorphine still more so. The same characteristics were found for the protective action of the three antagonists in acutely morphinized mice and the same order for their potencies in precipitating abstinence in acutely morphinized mice. Like naloxone, naltrexone and diprenorphine facilitated a nociceptive reaction in normal mice.The abstinence signs precipitated in acutely morphinized rats or mice are probably not unmasked excitatory effects of morphine as such effects should have been increased rather than inhibited by previous administration of specific antagonists; they might correspond to potentiated effects of the antagonists themselves. The prevention by specific antagonists of the abstinence syndrome is most simply interpreted by antagonism (direct or indirect) of dependence induction, but other interpretations are not excluded.

     

Minor physical anomalies and family adversity as risk factors for violent delinquency in adolescence

OBJECTIVE: Minor physical anomalies are considered indicators of disruption in fetal development. They have been found to predict behavioral problems and psychiatric disorders. This study examined the extent to which minor physical anomalies, family adversity, and their interaction predict violent and nonviolent delinquency in adolescence. METHOD: Minor physical anomalies were assessed in a group of 170 adolescent boys from low socioeconomic status neighborhoods of Montréal. The boys had been enrolled in a longitudinal study since their kindergarten year, when an assessment of family adversity had been made on the basis of familial status and the parents' occupational prestige, age at the birth of the first child, and educational level. Adolescent delinquency was measured by using self-reported questionnaires and a search of official crime records. RESULTS: Results from logistic regression analyses indicated that both the total count of minor physical anomalies and the total count of minor physical anomalies of the mouth were significantly associated with an increased risk of violent delinquency in adolescence, beyond the effects of childhood physical aggression and family adversity. Similar findings were not found for nonviolent delinquency. CONCLUSIONS: Children with a higher count of minor physical anomalies, and especially a higher count of anomalies of the mouth, could be more difficult to socialize for different and additive reasons: they may have neurological deficits, and they may have feeding problems in the first months after birth. Longitudinal studies of infants with minor physical anomalies of the mouth are needed to understand the process by which they fail to learn to inhibit physical aggression.     

Behavioural Development in Children of Divorce and Remarriage

We employed an autoregressive modelling technique with data from the Quebec Longitudinal Study to prospectively examine the developmental impact of family transition on behaviour while controlling for predivorce and preremarriage effects. Teachers rated children's anxious, hyperactive, physically aggressive, oppositional, and prosocial behaviour every 2 years from kindergarten through to the end of elementary school.Once individual and parental characteristics and antecedent family events were controlled, children who experienced parental divorce before age 6 exhibited comparatively more behavioural disturbance than their peers whose parents divorced later. With the exception of a protective effect on hyperactive behaviour, remarriage did not have a significant impact on children's behaviour when the legacy of divorce was controlled.Although the results suggest that children of divorced parents show difficulty in many areas of functioning, the effects of family transition on behavioural development were dependent on the child's age and the specific behavioural dimension assessed.Compared to other points in development, early childhood divorce was associated with long-term increases in anxious, hyperactive, and oppositional behaviour during later childhood.The effects of divorce on children's fighting were short-lived.Unlike previous prospective studies that suggest predivorce effects, we did not observe behavioural disturbance prior to divorce or remarriage.     

Problem-based learning in occupational therapy: why do health professionals choose to tutor?

For over 20 years the occupational therapy programmes offered by McMaster University and Mohawk College, Hamilton, Ontario have used small-group, problem-based learning tutorials as a major component of their curriculum. These programmes were among the first occupational therapy programmes in the world to use a problem-based tutorial format. The inclusion as tutors of both full-time faculty and clinicians, from all clinical practice areas, was central to the design of the problem-based learning courses. A survey of all tutors from the last 20 years collected information about why health professionals are motivated to tutor and what they see as challenges to maintaining this educational role. Three primary themes emerged from the data: being an educator; being a learner and present and future challenges to continuing with the tutoring role. Within the educator theme there was a secondary theme of professional duty or obligation. In addition, the participants identified suggestions for enhanced support and continuing education for tutors. This article summarizes the findings of the survey.     

Feasibility of a randomized controlled trial testing nifedipine vs. placebo for the treatment of preterm labor

AIMS: Nifedipine is believed to be a superior tocolytic agent on the basis of efficacy and side-effect profile, but was never prospectively evaluated in a placebo-controlled randomized clinical trial (RCT). In our study, we sought to identify limitations in participation for a would-be RCT comparing nifedipine to placebo. METHODS: A prospective feasibility study was conducted at Ste-Justine Hospital, a tertiary care center, on women between 24 and 34 weeks' gestation, presenting to the labor and delivery room with obstetrical complaints. Patient information was collected and would-be participants were identified on the basis of pre-established clinical and ultrasound criteria as well as on willingness to participate, as determined by the study research nurse. RESULTS: During a 6-month period, 483 women presenting with signs and symptoms of preterm labor (PTL) were eligible for further evaluation. A total of 321 (66.5%) women were excluded for obstetrical and medical reasons whereas 125 (25.9%) did not meet strict inclusion criteria (cervical length <25 mm or positive fetal fibronectin). When using strict criteria, only 37 women (7.6%) were found to be eligible for study participation. Subject willingness to participate as assessed by the research nurse was 50%. CONCLUSIONS: If adhering to strict inclusion/exclusion criteria, the feasibility of an appropriately sampled RCT testing tocolytic therapy against a placebo would require a large concerted multicenter effort to meet sample size demands.     

Identifying Counseling Needs of Nulliparous Adolescent Intrauterine Contraceptive Users: A Qualitative Approach

PurposeTo describe the intrauterine contraception (IUC) adoption process among nulliparous adolescents and to identify the role of the medical provider in this trajectory.MethodsWe conducted semistructured interviews with a clinic-based sample of 20 nulliparous adolescents (aged 15–24 years) with a history of IUC use. Interviews were analyzed using modified grounded theory and cross-case analysis to reveal a process model for IUC adoption, with a focus on the role of the medical provider.ResultsThe model includes the following stages: first awareness, initial reaction, information gathering, adoption, and adjustment and reassessment. It is influenced by personal preferences and experiences, friends, family, sexual partner(s), and medical providers. Interactions with medical providers that study participants found helpful in navigating the adoption process included the use of visuals; tailored counseling to address specific contraceptive needs; assurance that IUC discontinuation was an option; information on a wide range of side effects; medical provider self-disclosure regarding use of IUC; and addressing and validating concerns, both before and after IUC insertion.ConclusionsNulliparous adolescents in this study described a complex IUC adoption process in which the medical provider plays a substantial supportive role. Findings from this study may be used to counsel and support future nulliparous adolescents regarding IUC use.     

Effectiveness of virtual reality exposure therapy for active duty soldiers in a military mental health clinic

Exposure therapy is an evidence-based treatment for posttraumatic stress disorder (PTSD), but research evaluating its effectiveness with active duty service members is limited. This report examines the effectiveness of virtual reality exposure therapy (VRE) for active duty soldiers (N = 24) seeking treatment following a deployment to Iraq or Afghanistan. Relative to their pretreatment self-reported symptoms on the PTSD Checklist, Military Version (M = 60.92; SD = 11.03), patients reported a significant reduction at posttreatment (M = 47.08; SD = 12.70; p < .001). Sixty-two percent of patients (n = 15) reported a reliable change of 11 points or more. This study supports the effectiveness of exposure therapy for active duty soldiers and extends previous research on VRE to this population.     

Heparin-induced thrombocytopenia syndrome as a cause of flap failure: a report of two cases.

BACKGROUND: Flap failure is a major complication in reconstructive plastic surgery. One of the most frequent etiologies of flap failure is venous thrombosis. However, infrequent causes also need to be explored, especially when faced with recurrent thrombosis. Heparin is frequently used in the prevention of venous thrombosis; however, the use of the medication itself may cause a serious thromboembolic state via an immune-related pathophysiological process. This adverse reaction to heparin may be life threatening. CASE PRESENTATION: We present two cases, one pedicled and one free flap, with venous congestion concomitant to heparin-induced thrombocytopenia syndrome, in conjunction with severe life-threatening sequelae. CONCLUSIONS: Heparin-induced thrombocytopenia syndrome can be the cause of postoperative venous congestion. It is necessary to be alert for this syndrome in the presence of recurrent unexplained venous thrombosis or thrombocytopenia in patients receiving anticoagulation therapy.