Search PubMed⌕ Search

Biomedical subjects

David Cohen

Publications and source records attributed to David Cohen.

At least 73 records · Page 4Linked to original sources
PubMed2003

Aggression and the three opioid families (endorphins, enkephalins, and dynorphins) in mice.

Previous studies suggest that brain opioid activity decreases aggression in animal models. The main objective of the current study was to examine the possible genetic relationship between intermale aggression and brain levels of enkephalins, endorphins, and dynorphins in 11 inbred strains of mice. Pursuit, rattling, and attack behaviors were observed in a dyadic encounter with a standard opponent. It appeared that, as expected, enkephalins and endorphins were always negatively correlated with aggression scores. The findings indicate that brain Met5-enkephalin levels were significantly and highly positively correlated with attack latency. Brain adrenocorticotrophic hormone (ACTH) and beta-endorphin levels were significantly and negatively correlated with the number of rattlings, which is consistent with the hypothesis that rattling is a stress-related behavior. In contrast with Met5-enkephalin, ACTH and beta-endorphin, the correlations between dynorphin A and aggression scores were nonsignificant and very low. These preliminary results suggest that common genetic sources of variation contribute to differences between the 11 inbred strains in both endogenous opioidergic systems and intermale aggression. Further studies are required to confirm the genetic relationship between offensive aggression and brain enkephalins and endorphins and to better understand the mechanisms underlying the role of endogenous opioids in offensive aggression with regard to opioid receptor activity.

Adrenocorticotropic Hormone↗
PubMed2003

[Autism: toward a necessary cultural revolution].

Autism is a pervasive developmental disorder of childhood characterised by disturbances in both social interactions and communication as well as stereotyped patterns of activities and behaviour. The increase in estimates of the prevalence of autism has raised the question of an "epidemic" of autism. More active case assessment and changes in diagnostic criteria probably account in large part for such increase. Investigators have attempted to define the neural pathophysiology of autism ever since the hypothesis of "refrigerator mother" as its cause was replaced by the view that it is a developmental disorder of the immature brain. However consensus is yet to be reached concerning the brain regions implicated. Psychoanalysis, cognitive psychology, neurophysiology, neuropharmacology, and genetics propose restricted view of the major issues leaving extensive areas unexplored. Therapeutic approaches induce only partial and uncertain results. There is no cure for autism but substantial evidence indicates that early, intensive, individualised education is beneficial for children. All modern intervention programs for autism affected children share a high degree of environmental structuring and predictability and an extensive individual approach. Autism being a behaviourally defined syndrome, it gave rise to a number of controversies concerning definition, classification, etiopathogenesis and therapeutics. In the 1990s a crisis has occurred in France with a loss of confidence between parents and psychiatrists with a problem concerning the means and ways of care of the autistic individual. The aim of this paper is to point out the different questions raised by autism in order to better understand this syndrome which touches upon essential behaviour-related aspects such as self consciousness, reality perception, the functioning of the thought and communication, as well as the role of hereditary and acquired influences in normal and pathological development.

Autistic Disorder↗
PubMed2003

British Association of Stroke Physicians: benchmarking survey of stroke services.

BACKGROUND: the National Service Framework for Older People requires every general hospital which cares for stroke patients to introduce a specialist stroke service by 2004. OBJECTIVE: to describe the organisation and staffing of specialist hospital-based stroke services in the UK. DESIGN: a national postal survey of consultant members of the British Association of Stroke Physicians (BASP) seeking details of the provision of neurovascular clinics, acute stroke units (ASUs), stroke rehabilitation units (SRUs), and the organisation and staffing of these services. RESULTS: the response rate was 91/126 (72%). Fifty-four neurovascular clinics, 40 ASUs and 68 SRUs were identified. Neurovascular clinics used a number of strategies to maintain rapid access and 30 (56%) were run by a single consultant. Only 50% ASUs usually admitted patients within 24 h of stroke. As the number of beds available on ASUs and SRUs did not reflect the total number of stroke in-patients, 21 (53%) ASUs and 45 (79%) SRUs had admission criteria. Training opportunities were limited: 37% ASUs and 82% SRUs had no specialist registrar. The therapy sessions (1 session=half a day) available per bed per week on a SRU were: physiotherapy 0.8; occupational therapy 0.6; speech and language therapy 0.25. CONCLUSIONS: significant development is needed to achieve the NSF target for hospital-based stroke services as few Trusts currently have all components in place and even when available not all stroke patients have access to specialist care. Stroke specialists will be required to run these services but training opportunities are currently limited. Stroke unit therapy staffing levels were lower than was available in randomised controlled trials.

Aged↗
PubMed2003

Paroxetine versus clomipramine in adolescents with severe major depression: a double-blind, randomized, multicenter trial.

OBJECTIVE: To date, two randomized, double-blind trials of serotonin reuptake inhibitors (SRIs) have shown that antidepressant drugs are effective in treating adolescent depression. In contrast, tricyclic antidepressants (TCAs) are not superior to placebo. This has led to a serotonin hypothesis in this age group. This study explores this hypothesis and compares paroxetine, a specific SRI, with clomipramine, a TCA with SRI activity. METHOD: One hundred twenty-one adolescents (aged 12-20 years) with major depression were enrolled and randomized (stratified for age) to 20 or 40 mg of paroxetine or 75 mg or 150 mg of clomipramine for 8 weeks. Primary outcome measurements were the Clinical Global Impression (CGI) scale and the Montgomery and Asberg Depression Rating Scale (MADRS). RESULTS: Of the 121 patients, 58 received clomipramine and 63 paroxetine. Based on intent-to-treat analysis, both agents had similar efficacy, with no effect of age; 48.3% and 58.2% of the subjects receiving clomipramine and 65.1% and 59.3% of those receiving paroxetine were rated responders on the MADRS and CGI scales, respectively. Study withdrawals were frequent in both groups (41% and 31%, respectively), but side effects were significantly more frequent with clomipramine (69% versus 49.2%, respectively; p = .027). CONCLUSION: Paroxetine and clomipramine exhibit similar efficacy in adolescent depression. These data support the serotonin hypothesis but do not confirm it in the absence of a placebo arm. Given the adverse event profile of clomipramine, specific SRIs should be preferred. However, more placebo-controlled studies are needed to establish definitively the efficacy of SRIs in this age group.

Adolescent↗
PubMed2003

The effect of hydrogen peroxide applied to the middle ear on inner ear function.

OBJECTIVES/HYPOTHESIS: The objective was to assess the effect of hydrogen peroxide applied to the middle ear on cochlear and vestibular function. STUDY DESIGN: Prospective animal study. METHODS: Sand rats underwent a right-side total labyrinthectomy, and a polyethylene tube was inserted into the left-side middle ear. Following baseline recordings of vestibular evoked potentials in response to linear acceleration stimuli and auditory brainstem response, each experimental animal received five daily applications of hydrogen peroxide into the left-side middle ear. Two control groups received saline and gentamicin, respectively. Subsequently, recordings were repeated and compared with baseline measurements. RESULTS: Saline administration affected neither vestibular evoked potentials nor auditory brainstem response. In contrast, both responses could not be recorded following gentamicin application. After hydrogen peroxide administration, auditory brainstem response could not be recorded in 25% (3 of 12) of the animals, whereas in the remaining nine animals the average auditory brainstem response threshold was significantly elevated by 55 dB (P =.000002). Linear vestibular evoked potentials could not be recorded in 42% (5 of 12) of the animals. CONCLUSION: It appears that topical hydrogen peroxide adversely affects both cochlear and vestibular function of the sand rat. The study demonstrated the effect of a reactive oxygen species on inner ear function and may be useful in the study of mechanisms responsible for this damage and its protection. Clinically, although an animal model was used in the present study, caution should be exercised when large amounts of hydrogen peroxide are applied to a dry, perforated ear.

Administration, Topical↗
PubMed2003

Case study: effectiveness of plasma exchange in an adolescent with systemic lupus erythematosus and catatonia.

Catatonia is a rare but severe condition in adolescents that can be associated with both psychiatric and organic causes. The present report notes that systemic lupus erythematosus should be considered among possible causes of catatonia and shows that plasma exchange could be an efficient treatment option for such neuropsychiatric manifestations of systemic lupus erythematosus, to avoid the use of electroconvulsive therapy in young patients.

Adolescent↗
PubMed2003

Early events in the Fusarium verticillioides-maize interaction characterized by using a green fluorescent protein-expressing transgenic isolate.

The infection of maize by Fusarium verticillioides can result in highly variable disease symptoms ranging from asymptomatic plants to severe rotting and wilting. We produced F. verticillioides green fluorescent protein-expressing transgenic isolates and used them to characterize early events in the F. verticillioides-maize interaction that may affect later symptom appearance. Plants grown in F. verticillioides-infested soil were smaller and chlorotic. The fungus colonized all of the underground parts of a plant but was found primarily in lateral roots and mesocotyl tissue. In some mesocotyl cells, conidia were produced within 14 to 21 days after infection. Intercellular mycelium was detected, but additional cells were not infected until 21 days after planting. At 25 to 30 days after planting, the mesocotyl and main roots were heavily infected, and rotting developed in these tissues. Other tissues, including the adventitious roots and the stem, appeared to be healthy and contained only a small number of hyphae. These results imply that asymptomatic systemic infection is characterized by a mode of fungal development that includes infection of certain tissues, intercellular growth of a limited number of fungal hyphae, and reproduction of the fungus in a few cells without invasion of other cells. Development of visibly rotted tissue is associated with massive production of fungal mycelium and much less organized growth.

Fusarium↗
PubMed2003

Is secretory otitis media a single disease entity?

The outcome of 809 children who had middle ear effusion (MEE) was correlated with their age and medical history and the bacteriologic and cytologic findings of the MEE. Three groups emerged. Group A (n = 384) had a medical history of relatively recent acute otitis media (AOM) with a peak prevalence of 2.6 years of age, and its MEE was hypercellular (mostly polymorphonuclear leukocytes) with a 24% rate of positive bacteriologic culture. In contrast, the peak prevalence of group B (n = 280) was approximately 5 years of age. Its MEE followed no otologic medical history and was bacteriologically sterile with relatively few cells (mostly lymphocytes typical of viral infections). Group AB (n = 145) resembled group B except that they had a history of AOM some years before hearing loss onset. Altogether, the clinical features of group A are statistically distinguishable from those of groups B and AB in most respects. These findings explain the bimodal peak prevalence distribution that was found in many available epidemiological studies of secretory otitis media (SOM) and that was also seen in our data. It appears that SOM should neither be termed nor treated as an otitis media, but as a sequela of either bacterial AOM (group A) or of insidious, asymptomatic, probably viral otitis media (groups B and AB). Our data do not support antibiotic treatment for SOM (otitis media with effusion)--especially not in chronic cases.

Acute Disease↗
PubMed2003

The differential vulnerability of the inner ear end-organs to several external factors.

In a number of recently conducted animal studies, the effect of various external factors such as ototoxic substances, different types of noise and systemic disease on the different end-organs of the inner ear has been investigated. These studies are distinguished by the use of short latency vestibular evoked potentials (VsEPs) (to both linear and angular acceleration), an objective method for directly assessing the function of the different vestibular end-organs. In addition, the well known auditory brainstem response (ABR) was used to assess cochlear function. The studies are reviewed and it appears that the general pattern of effect is as follows: ABR (cochlea) is the most sensitive to the various external factors; angular VsEPs (semicircular canals) the least sensitive; linear VsEPs (otolith organs) intermediate between them.

Diabetes Complications↗
PubMed2003

Aggression: the testosterone-serotonin link.

The relevance of central neurotransmission to aggressive and impulsive behavior has become more evident due to extensive research in humans and animals. Among other findings, there are abundant data relating low serotonergic activity--as measured by low cerebrospinal fluid 5-hydroxyindolacetic acid, and a blunted response of prolactin to fenfluramine--to impulsive behavior. Many studies on testosterone activity show a relation between high plasma levels and a tendency towards aggression. It is hypothesized that the interaction between low serotonin and high testosterone levels in the central nervous system has a significant effect on the neural mechanisms involved in the expression of aggressive behavior. It seems that testosterone modulates serotonergic receptor activity in a way that directly affects aggression, fear and anxiety. Our survey reviews the main findings on serotonin, testosterone and the possible interaction between them with regard to these behavioral phenomena.

Aggression↗
PubMed2003

Cluster-randomised trial of risk communication to enhance informed uptake of cervical screening.

BACKGROUND: Women overestimate both population and individual risk of cervical cancer. This may contribute to the recognised excess screening frequency for low-risk women. AIM: To investigate whether an individualized risk communication package could affect stated preferences for screening interval and actual screening behaviour. DESIGN: Pragmatic, practice-based cluster randomised controlled trial. SETTING: Twenty-nine practices (15 intervention, 14 control) in North Wales recruited 1890 women attending for cervical smears. METHOD: A risk communication package containing visual material was compared with normal practice. Practice nurses received training in its delivery. The short-term primary outcome was stated preference for screening interval; the long-term primary outcome was actual screening behaviour. RESULTS: In the short term, intervention arm women were significantly less likely to prefer a shorter than recommended interval (odds ratio [OR] = 0.51, 95% confidence interval [CI] = 0.41 to 0.64; P < 0.0001). At the five-year follow-up, fewer women in the intervention arm had attended for screening sooner than their recommended recall. The magnitude of difference in excess screening interval preference and behaviour was similar, but behaviour had a wider confidence interval and a marginally non-significant P-value (OR = 0.61, 95% CI = 0.36 to 1.03; P = 0.063). Better knowledge and more accurate risk perceptions were demonstrated, with an improvement in measures of anxiety. The extra cost per woman receiving the intervention was 6 Pounds. CONCLUSIONS: Women's perception of risk contributes to determining screening intervals in addition to practice factors. Simple risk information delivered in primary care affected women's stated preferences for tests. The impact on actual screening behaviour was more equivocal. Overall, the intervention showed a substantial benefit and any disbenefit can be ruled out. This approach to providing risk information could, at low cost, benefit other screening programmes and may relieve anxiety.

Adult↗
PubMed2003

Screening for depression: preventive medicine or telemarketing?

In this editorial, the authors critically examine a recent recommendation by the United States Preventive Services Task Force that all adults visiting primary care practitioners be routinely "screened" for depression. Drug industry funding for depression screening campaigns, popular but unproven assertions that depression is a "biochemical disorder," and the banality of antidepressant prescribing are seen to motivate the proposal. The full report cited by the Task Force omits information on the lack of effectiveness of antidepressants compared to placebo and recognizes that the potential harms of screening have not been studied.

Adult↗
PubMed2002

Intraocular lens power calculation after macular hole surgery.

A patient had cataract surgery in both eyes after bilateral macular hole repair. In the left eye, the intraocular lens power was calculated using the axial length obtained by biometry. In the right eye, 0.5 mm, the estimated depth of the foveolar crater after stage 3 macular hole repair, was subtracted from the A-scan measurement to obtain the functional axial length. Postoperatively, refraction was +0.25 diopter (D) in the right eye and +1.63 D in the left eye. Biometry after macular hole surgery should be corrected by subtracting the depth of the foveolar crater from the measured axial length.

Aged↗
PubMed2002

Drug treatment of conduct disorder in young people.

Although conduct disorder (CD) is the most common psychiatric disorder in youth from the community and encompasses one third to one half of all referrals to child and adolescent clinics, there is no licensed drug, to date, for treatment of CD, neither in Europe nor in the US. The aims of this paper are to review research data available on the use of medication for CD in young people and to identify future directions for research. We review 17 controlled studies and six open trials. Investigated compounds mainly belong to three classes of psychotropic drugs: mood stabilizers, neuroleptics and stimulants (six, five and six controlled studies, respectively). Lithium is the most documented treatment (3/4 positive studies). Conventional neuroleptics have been most commonly prescribed (3/3 positive studies), atypical neuroleptics appear promising (2/2 positive studies). Methylphenidate improves some CD symptoms, even in the absence of ADHD (6/6 positive studies). Sparse research has been conducted on response to antidepressants. The evidence for an effective role of pharmacotherapy in CD is still limited. Treatment should be multimodal and individualized to each patient's specific condition.

Adolescent↗