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Biomedical subjects

M Lyons

Publications and source records attributed to M Lyons.

At least 19 recordsLinked to original sources
PubMed1997

Effects of clozapine, thioridazine, risperidone and haloperidol on behavioral tests related to extrapyramidal motor function.

Evidence indicates that the antipsychotic drug clozapine has a low propensity for the induction of extrapyramidal motor symptoms, and also that clozapine has therapeutic effects in patients with idiopathic Parkinson's disease. Because tacrine-induced tremulous jaw movements in rats have been suggested as a possible model of extrapyramidal motor dysfunctions, including parkinsonian tremor, the present work was undertaken to investigate the effects of clozapine on tremulous jaw movements. Clozapine decreased tacrine-induced tremulous jaw movements in a dose-related manner, with an ED50 of approximately 3.3 mg/kg. In order to determine the relative potency of this effect compared to other behavioral effects of clozapine, suppression of lever pressing was also studied. Clozapine reduced lever pressing in a dose-related manner, with an ED50 of approximately 5.4 mg/kg. This indicates that clozapine suppressed jaw movements at or below the doses required for suppression of lever pressing. In contrast, the typical antipsychotic drug haloperidol failed to suppress tacrine-induced tremulous jaw movements in doses up to 1.0 mg/kg, which is about 11-fold higher than the ED50 for suppression of lever pressing with that drug. Thioridazine and risperidone also suppressed tremulous jaw movements in roughly the same dose range at which lever pressing was reduced. It is possible that the suppression of tacrine-induced tremulous jaw movements by clozapine in rats is related to the unique behavioral and motor effects of clozapine. The ratio of potencies of these effects (i.e., suppression of tremulous jaw movements versus suppression of lever pressing) could be used as a behavioral procedure for assessing clozapine-like activity in novel compounds.

Animals↗
PubMed1997

Criteria for the diagnosis of sinus mycetoma.

Recent improvements in the treatment options for fungal disease of the sinuses make rapid distinction between the syndromes of invasive and noninvasive sinusitis necessary. On the basis of the extensive review of the literature detailed here, we developed case-finding criteria for the noninvasive syndrome of sinus mycetoma. Using these criteria, we identified 20 cases of sinus mycetoma in the medical literature and compared findings in these patients to those of five patients with mycetoma evaluated in our clinics. Like those in the literature, our patients appeared immunocompetent and were often first seen for evaluation of symptoms other than those usually associated with sinusitis. Two were first seen with a new-onset seizure disorder and one with nasal obstruction alone. Patients from both groups more commonly had mycetoma in their maxillary sinuses, and fungus failed to grow from the cheesy, grey-green, hyphae-rich material removed at the time of surgery. Clinical features in our five patients, which are not noted in published reports of sinus mycetoma, included frequent atopy, nasal polyps, calcification within the sinus on computed tomography, and an excellent response to surgical treatment. Serendipitously, one patient had both allergic fungal sinusitis and a mycetoma in the same sinus. On the basis of this experience, we have modified our case-finding criteria into proposed diagnostic criteria for sinus mycetoma. The elements of these criteria are designed to: (1) exclude patients with invasive fungal sinusitis and (2) differentiate sinus mycetoma from other forms of noninvasive fungal sinusitis on the basis of specific histopathologic findings. This study and the criteria presented reflect our view that sinus mycetoma represents a distinct but not necessarily isolated element in the spectrum of noninvasive fungal disease of the sinuses.

Adult↗
PubMed1997

Subacute infusion of physiological doses of parathyroid hormone raises blood pressure in humans.

BACKGROUND: Acute administration of parathyroid hormone (PTH) causes vasodilation and blood pressure decrease in experimental animals. This effect contrasts with the putative role of secondary hyperparathyroidism in the pathogenesis of hypertension of patients with renal failure. Uraemia is characterized by insulin resistance and hyperinsulinaemia. We therefore investigated whether subacute administration of physiological doses of human 1,34-PTH affects blood pressure under conditions of controlled insulin levels (euglycaemic clamp technique) in humans. METHODS: In a double-blind cross-over design 10 healthy male subjects received, on two occasions, in random order, for 2 h, either a sham infusion or an infusion of 200 units of 1,34-PTH. RESULTS: Mean ionized calcium concentration increased significantly (P < 0.01) within the normal range during euglycaemic hyperinsulinaemia, both with sham infusion (from 1.25 +/- 0.04 to 1.29 +/- 0.02 mmol/l) and with infusion of 1,34-PTH, but the increase was more marked with 1,34-PTH administration (from 1.26 +/- 0.05 to 1.33 +/- 0.07). In addition, mean platelet intracellular calcium concentration (by fluorescence spectroscopy) was unchanged with sham infusion (49.9 +/- 4.1 versus 50.3 +/- 5.0 nmol), but increased significantly (P < 0.05; paired t-test) after 1,34-PTH infusion (from 49.8 +/- 5.0 to 52.8 +/- 5.8). The infusion of 1,34-PTH resulted in a significant (P < 0.01) increase in mean MAP (from 84 +/- 5 to 88 +/- 5 mmHg) as compared with sham infusion (85 +/- 4 versus 86 +/- 4). The intra-individual changes in intracellular calcium concentration (delta[Ca2+]i) were significantly correlated to the changes in mean MAP (delta MAP) (r = 0.87, P < 0.001). In contrast to blood pressure, insulin sensitivity was not affected by 1,34-PTH infusion (M-value: 7.2 +/- 1.6 mg/kg per min) as compared with sham infusion (7.3 +/- 1.4). CONCLUSION: Subacute administration of physiological doses of parathyroid hormone under hyperinsulinaemic conditions significantly affects intracellular calcium and blood pressure in healthy subjects, but does not affect the action of insulin.

Adult↗
PubMed1997

Extent of comorbidity between mental state and personality disorders.

Comorbidity between major psychiatric disorders (Axis I) and personality disorders (Axis II) is widespread, often extremely strong, and invariably confusing. The strongest associations are found between substance use and the cluster B (flamboyant) personality disorders, anxiety disorders and the anxious/fearful personality group (cluster C), and between somatisation and both cluster B and C disorders. The significance of these associations is far from clear, and almost certainly include more than one type of relationship. Empirical studies of patients with and without Axis I and II comorbidity show that the presence of a personality disorder can affect the outcome of treatment, both positively and negatively, in a way that currently appears unpredictable. One useful way of interpreting this comorbidity is by postulating personality dispositions that make some people prone to certain mental state disorders.

Comorbidity↗
PubMed1997

Understanding professional behavior: experiences of occupational therapy students in mental health settings.

A phenomenological study explored occupational therapy students' experiences in psychiatric fieldwork. Of particular interest was students' understanding of professional behavior toward persons who use mental health services. Data were gathered from 16 informants via in-depth interviews and participant observation on multiple occasions during fieldwork affiliations. Emerging from informants' views of professional behavior were difficulties in their reconciling conflicting expectations with regard to emotional and social distance from persons who use mental health services. Additionally, the informants experienced a need to assume authority and maintain control in their dealings with service users. Students' encounters with such issues during fieldwork are indicative of challenges they may face as health professionals in a changing climate of mental health services. These data are stimuli for reflection on features of professional relationships with service users, particularly in response to expectations of persons with disabilities regarding control over their lives.

Adult↗
PubMed1996

Influence of nicotine on myocardial stiffness and fibrosis during chronic ethanol use.

Cardiomyopathy related to ethanol abuse is often accompanied by cigarette use. To examine if the major cardioactive component may intensify the abnormal function and composition induced by chronic ethanol, nicotine was administered orally, 2.5 mg bid, to a canine model receiving 36% of calories as ethanol for 6 months (group III). These animals were compared with group II receiving ethanol alone, group IV on nicotine alone, and controls (group I). In the intact, ventilated, anesthetized dog, left ventricular pressures and volumes were measured before and after dextran infusion and related to left ventricular collagen alterations. Basal heart rate, aortic pressure, and ejection fraction were comparable with controls. End-diastolic pressure and diastolic chamber stiffness (KPV) were significantly higher in the basal state and during dextran infusion in the three experimental groups, compared with group I. The increment was largest in the ethanol-nicotine group. Analysis of left ventricular myocardium revealed a rise of collagen concentrations in all three experimental groups, with an interstitial distribution on histochemical examination. Moreover, determination of advanced glycosylation endproducts, as a measure of alterations in collagen cross-links, revealed higher concentrations versus controls. The greater increase of diastolic stiffness in the nicotine-ethanol group occurred despite a similar concentration of fluorescent products as group II. Because the former had a larger increase of collage concentration, total cross-linked collagen content was presumably greater after the combined use of nicotine-ethanol. Thus, nicotine in relatively high dose when combined with ethanol, elicited a modest further increase in the left ventricular chamber stiffness and collagen concentration.

Administration, Oral↗
PubMed1996

Familial vulnerability factors to post-traumatic stress disorder in male military veterans.

The question has been frequently raised about whether there are emotional disorders that predispose to post-traumatic stress disorder (PTSD). We do know that those with PTSD do have many comorbid disorders, but due to the difficulty in performing prospective studies it is hard to tell what is cause and what is effect. This study bypassed the problem caused by comorbidity by examining family history of four proband groups: PTSD, mixed anxiety disorders, coexisting anxiety and depressive disorders, and screened normal controls. Two questions were examined. First, whether family history predicted who experienced combat situations and second, whether the proband groups could be distinguished by family history. Logistic regression identified two variables that predicted the experience of combat: major depression (odds ratio 2.17) and the DSM-III dramatic personality disorder cluster (odds ratio 1.36). Although there was considerable overlap, family history variables distinguished PTSD from other proband groups. Overall, the pattern of psychopathology in the families of the PTSD probands most closely resembled that in the families of the coexisting anxiety and depressive disorders probands. We conclude that family history methods may be an addition to possible variables that predict who will be exposed to combat and also that family history variables may be able to distinguish a PTSD population from some other types of emotional disorders.

Adult↗
PubMed1996

Process over person?: occupational therapy students' fieldwork experiences of people in psychiatric settings.

This paper explores influences of psychiatric service system processes on occupational therapy students' understanding of people with psychiatric disorders. The fieldwork experiences of 16 occupational therapy undergraduates in clinical settings were studied via in-depth interviews and participant observation. An important part of the students' understanding of people with psychiatric disorders arose from the manner in which the psychiatric service system and occupational therapists have structured their dealings with people as patients or clients. Students were influenced by system practices such as the classification of people as acute/chronic, and a heavy emphasis on quantitative performance indicators of services rendered; along with an occupational therapy process that may be excessively problem-oriented, at the expense of attending to other significant personal and environmental factors within patients'/clients' lives. Such circumstances are likely to undermine students' appreciation of the humanity and individuality of people using the psychiatric service system.

Attitude↗
PubMed1995

Interrater reliability of the Glasgow Coma Scale.

The purpose of this study was to test the interrater reliability of the Glasgow Coma Scale (GCS) when used in assessing neurologically impaired patients. In order to control variables, a videotape was developed of seven patients with different neurological impairments. A total of 57 nurses and physicians with varying degrees of education and experience used the GCS to score the patient responses. These responses were then compared for consensus and against a criterion standard. The comparison showed a low disagreement rating and a moderate to high agreement rating demonstrating that this tool has good interrater reliability (p = 0.000). Nurses may use this tool with confidence as one measure of assessment in evaluating neurologically impaired patients.

Adult↗
PubMed1995

Changes in pathological narcissism.

OBJECTIVE: This study investigated types of change that occur over time in the psychopathology of narcissistic patients. METHOD: Baseline scores on the Diagnostic Interview for Narcissism of 20 patients, clinically diagnosed as having narcissistic personality disorder, were contrasted with their scores 3 years later by means of t tests and chi-square statistics. The authors then compared these changes in narcissism with the patients' accounts of their life events during the interval between the two assessments. RESULTS: A significant decrease in the overall level of pathological narcissism was found, particularly in the areas of interpersonal relations and reactiveness. At follow-up, 60% of the subjects had reached the cutoff score on the diagnostic interview that indicated significant improvement, and 40% remained unchanged, with a high level of pathological narcissism. A high baseline level of narcissism in interpersonal relations was associated with absence of change at follow-up. Examination of life events in the interval between assessments suggests that changes in pathological narcissism are related to three kinds of experiences: achievements, new durable relationships, and disillusionments. CONCLUSIONS: The instability of narcissistic psychopathology found in this study raises questions about the construct validity of narcissistic personality disorder as a diagnostic category and about the core construct of pathological narcissism.

Adult↗
PubMed1994

Recruitment order of motoneurons during functional tasks.

The recruitment order of motoneurons of first dorsal interosseous (1DI) muscle has been shown to be the same during either isometric abduction or flexion of the index finger. However, it is not known whether this stereotyped recruitment is the same for all functional tasks. This question was addressed by using the 1DI muscle, which contributes to many functional tasks involving the hand and fingers. Single motor units and surface electromyographic activity were recorded from 1DI in three human subjects. Each subject performed tasks of abduction of the index finger, rotation to unscrew a threaded knob and pincer to close a spring-loaded clip. The same motor units were activated for each of the three tasks, providing no evidence for the existence of task groups. The order of recruitment of pairs of selected motor units was the same for each of the three tasks.

Adult↗
PubMed1994

Sexually transmitted diseases in the history of Uganda.

First noticed in Uganda in 1863 by a European explorer, sexually transmitted diseases (STDs) were cited as a major cause of morbidity and mortality throughout this century. In 1908 the venereal diseases campaign was launched marking the real introduction of western medicine. By the mid-1920s, the campaign was combined with the medical service but throughout the colonial period (1901-1962) venereal diseases were considered intractable. A 1991 survey revealed alarming incidence rates and in light of the importance of STDs as a co-factor in the transmission of HIV, it is of paramount importance to implement more effective control measures.

HIV Infections↗
PubMed1994

Correlation between red blood cell deformability and changes in hemodynamic function.

BACKGROUND: In sepsis red blood cells (RBCs) have been shown to be less deformable (i.e., more rigid) and have been implicated in decreasing nutrient blood supply and possibly leading to organ dysfunction. However, no studies have demonstrated an association between organ dysfunction and rigid RBCs. This study examined cardiovascular physiologic and histologic changes in two different models to determine whether a relationship may exist between RBC deformability and organ function. METHODS: In the following two experiments, cardiac index (CI) was continuously measured, whereas both deformability index and histology were examined at the end of the experimental periods. The first experiment studied nonanesthetized, hydrated rats after a cecal ligation and puncture (CLP), a slow-developing means of inducing RBC rigidity. In a second experiment animals were anesthetized and received a 20% total blood volume transfusion of either diamide-treated (rigid) RBCs or normal RBCs. RESULTS: CLP-treated animals' CI gradually decreased during 18 hours (232 +/- 60 ml/min/kg to 123 +/- 90 ml/min/kg; p = 0.05), with an increase in systemic vascular resistance (1459 +/- 517 dyne.sec/cm5.m2 to 2337 +/- 1213 dyne.sec/cm5.m2; p = 0.02). Diamide-treated animals had a rapid decrease in CI (86 +/- 7.0 ml/min/kg to 58 +/- 13 ml/min/kg; p = 0.05) and increase in SVR (2269 +/- 373 dyne.sec/cm5.m2 to 3897 +/- 988 dyne.sec/cm5.m2; p = 0.05) from baseline to 120 minutes after treatment respectively. The DI was significantly lower in both CLP and diamide groups (p < 0.03) when compared with control animals. Histologic evidence of subendocardial necrosis was shown in both the CLP- and Diamide-treated animals. CONCLUSIONS: These data suggest an association with RBC deformability and organ function in both septic and nonseptic animal models.

Animals↗
PubMed1994

A case report of intracortical hemangioma. A forgotten intracortical lesion.

The differential diagnosis for lytic intracortical lesions consists primarily of osteoid osteoma and Brodie's abscess. A third, less-well-known lesion is the intracortical hemangioma. It has an identical appearance to the two aforementioned lesions on bone scan and radiographs. This case report will describe the magnetic resonance imaging appearance of intracortical hemangioma and how it might be differentiated from osteoid osteoma and Brodie's abscess.

Abscess↗