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Biomedical subjects

C Mason

Publications and source records attributed to C Mason.

At least 37 records · Page 2Linked to original sources
PubMed1996

Temporal integration of events within and between the cerebral hemispheres.

The effect of interhemispheric transmission time (IHTT) on temporal perception was investigated by comparing simultaneity thresholds under unimanual and bimanual stimulation conditions. In the unimanual conditions the tactile stimuli were delivered to the same hand and were received by the same hemisphere, but in bimanual conditions, where stimuli were delivered to different hands, interhemispheric communication was necessary in order to compare the timing of the two stimuli. Randomised order of stimulating the fingers of the hands was compared with consistent stimulation of each hand. Previous studies have used only consistent stimulation. Thirty-two undergraduate university students (16 males and 16 females) were tested. Bimanual simultaneity thresholds were significantly higher than unimanual. Previous research showing an absence of laterality effects for simultaneity judgements was confirmed, supporting a hemispheric equivalence model of temporal processing. Simultaneity thresholds were not affected by randomisation of stimulus location, indicating that expectancy effects were not responsible for the difference between bimanual and unimanual thresholds. The implication of these findings is that temporal perceptions are affected by the process of interhemispheric transmission.

Adolescent↗
PubMed1996

Prediction of ECT response: validation of a refined sign-based (CORE) system for defining melancholia.

BACKGROUND: The clinical validity of melancholia has been argued on the basis of its capacity to predict response to electroconvulsive therapy (ECT). We have argued that a sign-based (CORE) rating system of psychomotor disturbance can identify patients with melancholia. Therefore, the clinical validity of the CORE system was tested here in terms of its capacity to predict response to ECT. METHOD: The response of 81 patients with primary affective disorders to an individualised course of ECT was investigated. CORE scores and other clinical predictors were evaluated in terms of their capacity to predict effect size changes in symptoms and disability. RESULTS: CORE scores predicted ECT response, as did the presence of psychotic features. The combination of marked psychomotor change (high CORE scores) and psychotic features predicted the best response to ECT. CONCLUSION: This study supports the clinical validity of the CORE system for diagnosing melancholia.

Aged↗
PubMed1996

Multiple supernumeraries: the importance of clinical and radiographic follow-up.

The occurrence of multiple supernumerary teeth is a rare phenomenon. Three cases of multiple supernumeraries are presented which illustrate problems which may arise during long-term follow-up: resorption of adjacent teeth, enlargement of the follicles, movement of the unerupted teeth and development of further supernumeraries. These cases highlight the importance of adequate initial surveillance, anticipation of potential problems, assessing the risk-benefits of surgery and long-term monitoring, in some cases following the surgical removal of supernumeraries.

Adolescent↗
PubMed1996

Defining the personality disorders: description of an Australian database.

OBJECTIVE: We seek to improve the definition and classification of the personality disorders (PDs) and derive a large database for addressing this objective. METHOD: The paper describes the rationale for the development of a large set of descriptors of the PDs (including all DSM-IV and ICD-10 descriptors, but enriched by an additional 109 items), the design of parallel self-report (SR) and corroborative witness (CW) measures, sample recruitment (of 863 patients with a priori evidence of personality disorder or disturbance) and preliminary descriptive data. RESULTS: Analyses (particularly those comparing ratings on molar PD descriptions with putative PD dimensions) argue for acceptable reliability of the data set, while both the size of the sample and the representation of all PD dimensions of interest argue for the adequacy of the database. CONCLUSIONS: We consider in some detail current limitations to the definition and classification of the PDs, and foreshadow the analytic techniques that will be used to address the key objectives of allowing the PDs to be modelled more clearly and, ideally, measured with greater precision and validity.

Adult↗
PubMed1996

An overview of depression-prone personality traits and the role of interpersonal sensitivity.

A number of personality styles have been proposed as vulnerability traits to depression. In this paper methodological problems associated with identifying such traits are discussed. These include state effects contaminating personality scales and the issue of depressive heterogeneity. Potential depression-prone personality traits are then discussed, including obsessionality, neuroticism, dependency and cognitive dysfunction. High interpersonal sensitivity as a risk factor to depression is then discussed.

Depressive Disorder↗
PubMed1995

The changing pattern of day-care treatment for children in a London dental teaching hospital.

Day-stay general anaesthesia facilities may be employed to provide comprehensive dental care for children who are unable to accept treatment using alternative methods of patient management. This approach to delivery of care has been shown to be cost-effective, acceptable and efficaceous. This study was set up to investigate changes in the pattern of care provided in day-care facilities at a London dental teaching hospital over a 20-year period--1972 to 1992. The results show that the use of the facilities at this centre has increased with time, with a greater increase amongst older children in recent years. Although the main use is still for the treatment of caries, oral surgery procedures, especially those related to orthodontic treatment, have increased by 200% between 1982 and 1992. This correlates with the increase in older age groups being treated. Details of mean numbers of teeth restored and extracted for each age group are presented for 1992. They indicate, for the younger age groups, not only the high treatment needs of patients referred to the hospital, but also suggest a trend for more radical treatment planning in order to avoid further general anaesthesia. Readers are reminded that, despite its advantages, general anaesthesia should be avoided if possible.

Adolescent↗
PubMed1995

Is there a physiological basis for the couvade and onset of paternal care?

Couvade is the male experience of pregnancy and couvade syndrome incorporates a range of symptoms suffered by "pregnant" men. The aetiology of the couvade syndrome is unknown. Anthropologists, psychiatrists, nurses and sociologists have provided explanations for behaviour changes in "pregnant" men in terms of cultural pressure, intrapsychic processes and psychosocial adaptation to a new situation. The adoption of a biological perspective allows us to ask a new question: is there a physiological basis for the couvade syndrome? A fresh research agenda would include measurement of physiological change and a search for causation. Implications for nursing are outlined.

Animals↗
PubMed1995

Severe tracheal stenosis and operative delivery.

We report the management of anaesthesia for Caesarean section in a woman with severe extensive tracheal stenosis. Management was initially with spinal anaesthesia, but general anaesthesia became necessary as a result of profuse intra-operative bleeding. We describe the use of the Hayek oscillator cuirass ventilator to allow instrumentation of the larynx whilst maintaining respiratory support, and for weaning from mechanical ventilation.

Adult↗
PubMed1995

Unusual distribution of enamel hypoplasia in an 11-year-old child with Proteus syndrome.

An 11-year-old girl with Proteus syndrome attended our dental department because her teeth were sensitive to cold stimuli and because of the poor appearance of her anterior teeth. Extraoral examination revealed several of the previously reported craniofacial features of Proteus syndrome: facial and skull asymmetry, exostoses of the nasal bridge, and mandibular prognathism. Intraoral examination revealed enamel hypoplasia of primary and permanent teeth. The distribution of hypoplasia was unusual in that only teeth on the right side of the mouth were affected, and also in that only the distal half of the crown of the maxillary right permanent central incisor was affected. Behavioural problems necessitated treatment under general anaesthesia; the affected primary teeth were extracted and the hypoplastic permanent teeth were restored, relieving the patient's symptoms and greatly improving aesthetics.

Child↗
PubMed1995

The prevalence of clinically significant anaemia and haemoglobinopathy in children requiring dental treatment under general anaesthesia: a retrospective study of 1000 patients.

There is little information on the possible value of screening children who are liable to haemoglobinopathies as part of pre-operative assessment for dental treatment under general anaesthesia. The present retrospective investigation examined, first, the number of patients having low haemoglobin levels among 1000 patients who had undergone haematological investigation prior to general anaesthesia in a dental outpatient unit, and, secondly, the subsequent clinical management of these patients. Haemoglobin levels of 10.0 g/dl or less were found in 31 children: 13 Asian, 7 Afro-Caribbean, 5 Mediterranean, 3 Arabic, 1 white Caucasian and 2 Oriental children. In addition, 17 patients had sickle-cell trait and 2 had beta-thalassaemia trait, but there was no relationship between the presence of haemoglobinopathy and low levels of haemoglobin. The planned general anaesthesia was undertaken for 22 of the 31 children who had low levels of haemoglobin and for the 19 children with haemoglobinopathy. Only 6 children ultimately did not undergo general anaesthesia, all failing to return. It is concluded that pre-anaesthetic haematological assessment of children needing minor dental surgery is rarely of any significant clinical value.

Adolescent↗
PubMed1995

Alcohol, tumor necrosis factor, and tuberculosis.

Alcohol exerts potent suppressive effects on the immune system that significantly increase host susceptibility to a variety of infections, particularly pneumonia. Historically, tuberculosis has been strongly associated with alcohol abuse. Although the relationship between alcohol abuse and tuberculosis is widely appreciated, the basic mechanisms by which alcohol immunosuppresses the host remain to be clarified. A major obstacle in furthering our understanding of this association has been the difficulty in distinguishing between the effects of alcohol per se and the other frequent sequelae of alcoholism such as nutritional deficiencies, liver disease, cigarette smoking, hygienic factors, and lifestyle. This article focuses on the role of tumor necrosis factor-alpha (TNF) in host defense and how alcohol modulates the activity of this important cytokine. While TNF's role in mediating the lethal consequences of infection has been the subject of much conjecture, this review focuses on the emerging evidence that TNF is an essential factor in the normal immune response to numerous infections, including tuberculosis.

AIDS-Related Opportunistic Infections↗
PubMed1995

Ethanol suppresses Mycobacteria tuberculosis-induced mRNA for nitric oxide synthase in alveolar macrophages, in vivo.

Acute ingestion of alcohol [ethanol (ETOH)] adversely affects the immunocompetence of both naive individuals as well as chronic alcohol abusers. An increased incidence and severity of tuberculosis is found in chronic alcohol abusers. Nitric oxide (NO) produced by alveolar macrophages (AMs) may play a role in the in vitro killing of Mycobacterium avium and Mycobacterium tuberculosis (MTB). Moreover, tumor necrosis factor-alpha (TNF-alpha) is believed to be a primary cytokine mediator of NO production by AMs. Recent studies from our laboratory demonstrated that ETOH suppressed endotoxin-induced increases in both TNF-alpha and NO in AMs, in vivo. We tested the postulate that acute ingestion of ETOH can interfere with mycobacteria-induced upregulation of the NO system in AMs, in vivo. We show that heat-killed M. avium complex (MAC) and human virulent MTB instilled into rat lungs rapidly increased mRNA for inducible NO synthase II (iNOS) of AMs in fluid obtained by bronchoalveolar lavage (BAL fluid). This was associated with production of reactive nitrogen intermediates [(RNIs); NO2- and NO3-] in BAL fluid, lung homogenate, and AMs in the absence of a significant increase in BAL fluid TNF-alpha. A single dose of ETOH (5.5 g/kg, ip) administered 30 min before intratracheal administration of MAC or MTB attenuated both MAC and MTB-induced increases in RNI in BAL fluid, lung, and AMs, and the increase in mRNA for iNOS. Thus, mycobacteria upregulate iNOS mRNA and enhance RNI production by AMs without any increase in the production of TNF-alpha. Moreover, ETOH attenuates mycobacteria-induced upregulation of mRNA for iNOS and RNI production in the absence of ETOH-mediated suppression of TNF. Speculatively, ETOH-mediated inhibition of the AM NO system may offer an explanation for the increased severity of mycobacterial infections in alcoholics.

Alcoholic Intoxication↗
PubMed1995

In vitro activity of D0870 compared with those of other azoles against fluconazole-resistant Candida spp.

We compared the in vitro activity of a new triazole, D0870, with those of fluconazole, itraconazole, and ketoconazole against 41 clinical isolates of fluconazole-resistant Candida belonging to nine different species. The 50% inhibitory concentrations (IC50s) were determined by a microdilution method with morpholinopropanesulfonic acid (MOPS)-buffered RPMI medium and an inoculum of approximately 10(4) yeasts per ml. After incubation for 48 h at 37 degrees C the optical density at 550 nm was measured. The IC50 was the lowest drug concentration which reduced the optical density at 550 nm by > or = 50% compared with that for a drug-free control. D0870 had significant activity against many of the isolates. Its activity was comparable to that of ketoconazole, slightly superior to that of itraconazole, and markedly superior to that of fluconazole against Candida albicans. Against Candida glabrata, Candida krusei, and Candida inconspicua, it had activity similar to those of itraconazole and ketoconazole but had activity superior to that of fluconazole. D0870 IC50s for some isolates were increased. This may be due to cross-resistance mechanisms because the IC50s of both itraconazole and ketoconazole for these isolates were often high. When IC50s and IC80s were compared there was a marked organism and drug variation. With C. glabrata much higher endpoints for itraconazole were observed when an IC80 endpoint was used. For C. albicans there was also a significant shift upward in endpoints for itraconazole and ketoconazole. Values were changed little when IC50 and IC80 endpoints of D0870 were compared. For 35 of 41 isolates tested the D0870 IC50 was less than the 2.5-mg/liter breakpoint threshold proposed previously. Therefore, D0870 may be a useful agent for the therapy of infections caused by fluconazole-resistant Candida spp.

Antifungal Agents↗
PubMed1995

Rapid induction of mRNA for nitric oxide synthase II in rat alveolar macrophages by intratracheal administration of Mycobacterium tuberculosis and Mycobacterium avium.

Mycobacterium avium complex (MAC) organisms are among the most common bacterial cause of disseminated infection in patients with acquired immune deficiency syndrome (AIDS). An increase in the incidence of virulent Mycobacterium tuberculosis (MTB) is also occurring throughout the world. In vitro data suggest that nitric oxide (NO) may be important in restricting the growth of MAC. However, the ability of MTB to stimulate NO production and the susceptibility of MTB to the bactericidal activity of NO produced by murine alveolar macrophages (AM) is controversial. This study tested the hypothesis that in vivo administration of heat-killed MAC (strain 100 and 101) and human virulent MTB (strain F1) to rats stimulated NO production by rat AM, ex vivo. We show that heat-killed MTB instilled into rat lungs rapidly induced mRNA for NO synthase (iNOS) II in AM obtained by bronchoalveolar lavage (BAL). In contrast, expression of AM iNOS mRNA was only found in 40% of the rats given MAC. Moreover, the change in iNOS mRNA in the AM obtained from rats given MTB and MAC correlated with the production of the reactive nitrogen intermediates (RNI) NO2- and NO3- in BAL fluid, lung homogenate, and the spontaneous generation of RNI by isolated AM ex vivo and occurred without measurable increases in BAL fluid tumor necrosis factor-alpha (TNF-alpha). L-NG-monomethylarginine (50 mg/kg, ip) given 30 min before MAC or MTB attenuated the increase in RNI in lung homogenates and BAL fluid. This is the first demonstration that in vivo exposure to MTB results in rapid upregulation of gene expression for iNOS which is associated with functional RNI production by rat AM. These results show that MTB human virulent strain 1 has the ability to rapidly upregulate iNOS mRNA in AM. If human AM generate NO from L-arginine by either iNOS or other NADPH oxidases then NO may play a role in the overall host-defense response of the lung to MAC and MTB.

Amino Acid Oxidoreductases↗