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Biomedical subjects

J R Davidson

Publications and source records attributed to J R Davidson.

At least 19 recordsLinked to original sources
PubMed1992

Cardiac arrest in Ontario: circumstances, community response, role of prehospital defibrillation and predictors of survival.

OBJECTIVES: To describe the patient characteristics, circumstances and community response in cases of out-of-hospital cardiac arrest; to evaluate the effect on survival of the introduction of prehospital defibrillation; and to identify factors that predict survival. DESIGN: Population-based before-and-after clinical trial. SETTING: Five Ontario communities: London, Sudbury, the Greater Niagara region, Kingston and Ottawa. PATIENTS: A consecutive sample of 1510 primary cardiac arrest patients who were transported to hospital by ambulance over 2 years. INTERVENTION: The use of defibrillators by ambulance attendants. MAIN OUTCOME MEASURES: Patient characteristics (sex and age), circumstances of arrest (place, whether arrest was witnessed and cardiac rhythm), citizen response (whether cardiopulmonary resuscitation [CPR] was started by a bystander, time to access to emergency medical services and time to initiation of CPR), emergency medical services response (ambulance response time, time to initiation of CPR and time to rhythm analysis with defibrillator) and survival rates. MAIN RESULTS: A total of 92.1% of the patients were 50 years of age or older, and 68.3% were men. Overall, 79.6% of the arrests occurred in the home. The average ambulance response time for witnessed cases was 7.8 minutes. The overall survival rate was 2.5%. The survival rates before and after defibrillators were introduced were similar, and the general functional outcome of the survivors did not differ significantly between the two phases. Factors predicting survival included patient's age, ambulance response time and whether CPR was started before the ambulance arrived. CONCLUSIONS: The survival rate was lower than expected. The availability of prehospital defibrillation did not affect survival. To improve survival rates after cardiac arrest ambulance response times must be reduced and the frequency of bystander-initiated CPR increased. Once these changes are in place a beneficial effect from advanced manoeuvres such as prehospital defibrillation may be seen.

Adult↗
PubMed1992

Social phobia: biological aspects and pharmacotherapy.

1. Social phobia is one of the anxiety disorders that until recently, had not been thoroughly investigated. 2. Social phobia is a relatively common anxiety disorder that appears to have a genetic basis. 3. There are certain physiological aspects of social phobia that separate it from the other anxiety disorders. 4. Support for a dopaminergic abnormality related to social phobia is supported by investigation studies and pharmacotherapy. 5. There are a number of studies reporting success in the treatment of social phobia with medications.

Adrenergic beta-Antagonists↗
PubMed1992

Fractures of the mandible and maxilla.

External fixation is an effective method for stabilization of many mandibular fractures. Thorough physical examination and patient stabilization should be instituted before attending to the fractures and associated soft tissue trauma. Normal occlusion rather than perfect reduction is the goal of oral fracture repair. Loose teeth or teeth in the fracture should be removed, as should any avascular bone fragments. Soft tissue wounds should be treated as for any contaminated wound. Mucosal wounds are allowed to heal by second intention. Although prophylactic perioperative antibiotics are indicated, they are usually not needed postoperatively. The three basic types of external fixators described include the Kirschner-Ehmer splint, pins or screws and acrylic, and the biphase splint. All three types are relatively easy to apply, and the principles of their application are similar. A minimum of two pins or screws are placed percutaneously in each fragment, avoiding the mandibular canal. The Kirschner-Ehmer splint is more easily adjustable than the biphase splint or the pin-acrylic splint, which use acrylic connecting bars. The advantages of fixators that use acrylic bars are that the pins or screws need not all be in the same plane and that they are more lightweight than the Kirschner-Ehmer splint. The disadvantages of the biphase splint are its increased expense and its use being limited to larger dogs. External fixators are well tolerated by the animals, and postoperative care is minimal. Mandibular fractures are usually healed in 3 to 5 weeks, and the fixators can be removed with the animal under sedation.

Animals↗
PubMed1991

Predictors of response to monoamine oxidase inhibitors: do they exist?

Multiple regression analysis was conducted on potential response predictors in a double-blind study of monoamine oxidase inhibitors (MAOI) and placebo treatment in 130 depressed outpatients. Positive main effects were found for sex (female), lack of prior hospitalization, presence of precipitating events. A negative main effect was found for concurrent physical illness. Treatment x predictor effects were found for distinct quality and non-reactivity. Non-reactivity was associated with positive outcome in the active drug group, but with negative outcome in the placebo group [corrected]. Distinct quality demonstrated a more complex effect, its presence being associated with decreased improvement in the treatment group and greater improvement in the control group. No atypical depressive symptoms predicted MAOI response, and we were unable to characterize a specifically responsive MAOI syndrome.

Adult↗
PubMed1991

Post-traumatic stress disorder in the community: an epidemiological study.

Post-traumatic stress disorder (PTSD) was studied in the Piedmont region of North Carolina. Among 2985 subjects, the lifetime and six month prevalence figures for PTSD were 1.30 and 0.44% respectively. In comparison to non-PTSD subjects, those with PTSD had significantly greater job instability, family history of psychiatric illness, parental poverty, child abuse, and separation or divorce of parents prior to age 10. PTSD was associated with greater psychiatric comorbidity and attempted suicide, increased frequency of bronchial asthma, hypertension, peptic ulcer and with impaired social support. Differences were noted between chronic and acute PTSD on a number of measures, with chronic PTSD being accompanied by more frequent social phobia, reduced social support and greater avoidance symptoms.

Adolescent↗
PubMed1991

Diagnostic issues in posttraumatic stress disorder: considerations for the DSM-IV.

Four issues of key interest with regard to posttraumatic stress disorder in the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) are discussed. These include: (a) how to define the stressor criterion, especially, whether or not the victim's response ought to be included and whether low-magnitude traumas qualify etiologically; (b) the cohesiveness of the syndrome and the validity of items across stressor groups; (c) the position of posttraumatic stress disorder within DSM-IV; and (d) comorbidity with other illnesses.

Dissociative Disorders↗
PubMed1991

The Brief Social Phobia Scale.

An observer measure of social phobic symptoms, referred to as the Brief Social Phobia Scale, consists of 11 items, 7 evaluating commonly feared or avoided situations and 4 additional items measuring autonomic distress. Symptoms represented by the scale items are found frequently in social phobia, and the instrument demonstrates acceptable interrater and test-retest reliability, internal consistency, concurrent validity against other measures of social phobia, and the ability of patients to change as a result of treatment. It can also detect differences between active treatment and placebo treatment. A comparison of the sensitivity of this scale with other scales in detection of size of effect also is presented.

Humans↗
PubMed1991

Long-term treatment of social phobia with clonazepam.

Twenty-six socially phobic outpatients were treated with clonazepam for the relief of symptoms. At evaluation, which took place after an average of 11.3 months of continuous treatment, 22 (84.6%) patients showed good improvement and 4 (14.4%) showed no improvement or were not recovered. The dose declined over time, from a peak mean of 2.1 mg/day to a mean of 0.94 mg/day at follow-up. Side effects are described, along with individual case descriptions that illustrate important aspects of the use of benzodiazepines for the treatment of social phobia.

Adult↗
PubMed1991

Levels of urinary free cortisol in social phobia.

Levels of urinary free cortisol were measured in 10 patients with social phobias and in 15 age- and sex-matched normal controls. No differences were found either in cortisol levels or in the ratio of free cortisol to creatinine. These nonsignificant differences between groups do not necessarily rule out the possibility that the hypothalamic-pituitary-adrenal axis may be altered in individuals with social phobia.

Adult↗
PubMed1991

Growth hormone and cortisol secretion in relation to sleep and wakefulness.

The study investigated secretory patterns of growth hormone (GH) and cortisol in relation to sleep and wakefulness. Plasma hormone levels were monitored in 10 young men during baseline waking and sleeping, during 40 hours of wakefulness, and during sleep following deprivation. The normal nocturnal GH surge disappeared with sleep deprivation, and was intensified following sleep deprivation. Mean GH levels were higher during slow wave sleep (SWS) compared with other sleep stages. During sleep after deprivation, GH secretion was prolonged, and second GH peaks occurred in three subjects which were not associated with SWS. Average 24-hour cortisol levels were not altered by sleep deprivation or sleep following deprivation, but the nocturnal cortisol rise occurred approximately one hour earlier with sleep deprivation and one hour later with resumed sleep, compared to baseline. This effect on the timing of the rise is consistent with an initial inhibitory influence of sleep on cortisol secretion. The results demonstrate that: the nocturnal growth hormone surge is largely sleep-dependent; temporal associations between GH and SWS are not reliable after sleep deprivation; although the cortisol rhythm is not sleep-dependent, the timing of the cortisol rise may be influenced by sudden changes in the sleep-wake schedule.

Adult↗
PubMed1990

Continuation treatment of panic disorder with high-potency benzodiazepines.

High-potency benzodiazepines such as clonazepam and alprazolam are effective and safe in the short-term treatment of panic disorder, but less is known about their effectiveness and safety over the long term. Further understanding of these issues is important since panic disorder is usually chronic and may call for long-term treatment. Available naturalistic data suggest that tolerance to the antipanic or antiphobic effects of clonazepam and alprazolam does not occur in panic disorder/agoraphobia; doses also tend to decrease over time. Withdrawal symptoms occur after short-term treatment with alprazolam, but less is known about clonazepam in this respect. Other issues discussed include management of withdrawal, clinical use of benzodiazepines, importance of comorbidity, and the use of benzodiazepines in association with behavior therapy.

Agoraphobia↗
PubMed1989

Classification of depression by grade of membership: a confirmation study.

One hundred and thirty out-patients with depression were studied by grade of membership multivariate (GOM) analysis. Five depressive types were generated. Pure Type I represented a mild form of melancholia in older, stable males, who showed a modest drug response. Pure Type II included obsessive-anxious symptoms in older patients who responded well to an MAOI drug, but poorly to placebo. Pure Type III was a mildly symptomatic form of depression which responded well to placebo. Pure Type IV included features of agitation, mood worsening later in the day, anorexia and depersonalization; it was commonly precipitated by external stress and MAOI treatment was more effective than placebo. In Pure Type V depression, patients were mostly younger females with high levels of symptomatology, atypical vegetative symptoms, unstable life-styles, disadvantaged backgrounds and a poor response to MAOI and placebo. These results resemble in many ways our earlier GOM study of depression, as well as other multivariate studies of depression in the literature.

Adult↗
PubMed1989

Effects of sleep deprivation on human immune functions.

The effect of 40 h of wakefulness on a variety of immunological parameters in the peripheral blood from 10 normal male subjects was studied. Sleep deprivation led to enhanced nocturnal plasma interleukin 1-like and interleukin 2-like activities. The rise in nocturnal response of lymphocytes to pokeweed mitogen stimulation during a normal 24 h sleep-wake cycle was delayed by sleep deprivation, but the response to the phytohemagglutinin mitogen was unaffected. With resumed nocturnal sleep, there was a prolonged decline in natural killer cell activity (measured as spontaneous cytolytic activity for human tumor cells) and return of an increased response to pokeweed mitogen. The altered patterns in immune functions occurred independently of the cortisol circadian rhythm, which remained unchanged.

Adult↗
PubMed1989

Pharmacotherapy in posttraumatic stress disorder: historical and clinical considerations and future directions.

Posttraumatic stress disorder (PTSD) has long been recognized as responsive to drug and somatic treatments. Clinical characteristics and patterns of treatment response were well described in the 1940s. Recent studies indicate that tricyclic antidepressants and monoamine oxidase inhibitors (MAOIs) have specific ameliorative effects on PTSD symptoms, but further work is needed in this regard. Goals of drug therapy are provided and future directions suggested.

Humans↗
PubMed1985

The shadow of life: psychosocial explanations for placenta rituals.

Culturally determined patterns of behavior associated with placenta disposal are characteristic of many modern and ancient societies. This paper defines this type of placenta disposal as a ritual event that delimits a "portion of reality"; explanations are provided leading to the conclusion that placenta rituals operate as anxiety releasing mechanisms that provide a means of control over the future health and welfare of mother, child, and community. The question of why the placenta figures so prominently in folk beliefs and practices has previously been attributed to its morphological and physiological properties; this paper argues that attributes associated with it from a psychosocial model are equally important. The data for this study were drawn from a compilation of ethnographic reports of post-partum practices in African, Asian, European, and Latin American societies. Additional information on placenta disposal was derived from interviews with 1,859 Peruvian informants. Analysis of the data obtained from the Peruvian studies show a significant difference between rural and semi-urban patterns of placenta disposal.

Ceremonial Behavior↗