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Biomedical subjects

K Ritchie

Publications and source records attributed to K Ritchie.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Mental-behavioral disorders in Alzheimer's disease].

Behavioural and psychological disorders are often observed in Alzheimer's disease. Some are common, such as symptoms of depression, apathy, aggressivity, agitation, psychotic disturbances, disorders of sleep rhythm, etc. Many factors contribute to the aetiology of these disorders, mainly cerebral lesions, environmental changes, somatic illnesses, iatrogenic factors and psychological reaction mechanisms. Management must take each into account. Treatment comprises medication (symptomatic treatment of the various disorders, cholinergic treatment) and other means (adaptation of the inhabitation, informing family and friends, psychotherapy, etc.).

Affective Symptoms↗
PubMed1998

Progressive disability in senile dementia is accelerated in the presence of depression.

OBJECTIVES: To assess the extent to which loss of ability to perform everyday activities in early stage senile dementia is worsened by the presence of depressive illness. METHODS: To evolution of disabilities is measured by an activity scale permitting observation of small changes in everyday performance in a cohort of 397 elderly persons with subclinical cognitive deficit. Over the 3 years of the study, 11% of the cohort developed dementia without depression and 5% dementia with depression. RESULTS: Progressive disablement was found to be greater in persons with senile dementia as compared to normal subjects. Depression alone had no significant effect over the time period. Persons with both senile dementia and depression had significantly higher rates of disability at 3 years than persons with senile dementia alone. Significantly greater decrements across the observation period were observed in dressing, washing, use of telephone and continence in the senile dementia-depression group only. CONCLUSION: Depression does not in itself engender significant disability, but interacts with senile dementia to accelerate loss of functioning. Effective treatment of depressive illness in senile dementia may have significant impact on the prevalence and severity of disability.

Activities of Daily Living↗
PubMed1998

Nitrogen balance for wheat canopies (Triticum aestivum cv. Veery 10) grown under elevated and ambient CO2 concentrations.

We examined the hypothesis that elevated CO2 concentration would increase NO3- absorption and assimilation using intact wheat canopies (Triticum aestivum cv. Veery 10). Nitrate consumption, the sum of plant absorption and nitrogen loss, was continuously monitored for 23 d following germination under two CO2 concentrations (360 and 1000 micromol mol-1 CO2) and two root zone NO3- concentrations (100 and 1000 mmol m3 NO3-). The plants were grown at high density (1780 m-2) in a 28 m3 controlled environment chamber using solution culture techniques. Wheat responded to 1000 micromol mol-1 CO2 by increasing carbon allocation to root biomass production. Elevated CO2 also increased root zone NO3- consumption, but most of this increase did not result in higher biomass nitrogen. Rather, nitrogen loss accounted for the greatest part of the difference in NO3- consumption between the elevated and ambient [CO2] treatments. The total amount of NO3(-)-N absorbed by roots or the amount of NO3(-)-N assimilated per unit area did not significantly differ between elevated and ambient [CO2] treatments. Instead, specific leaf organic nitrogen content declined, and NO3- accumulated in canopies growing under 1000 micromol mol-1 CO2. Our results indicated that 1000 micromol mol-1 CO2 diminished NO3- assimilation. If NO3- assimilation were impaired by high [CO2], then this offers an explanation for why organic nitrogen contents are often observed to decline in elevated [CO2] environments.

Absorption↗
PubMed1998

An ergonomic analysis of the fulcrum effect in the acquisition of endoscopic skills.

BACKGROUND: The loss of three-dimensional visual depth cues has been thought to be the main hindrance to the acquisition of endoscopic skills. However, the "fulcrum effect" of the abdominal wall on the manipulation of instruments has not to our knowledge been previously investigated. METHODS: Subjects with no experience in endoscopy were required to make multiple defined incisions under laparoscopic laboratory conditions, within ten two-minute periods in the first study and 50 in the second. Eleven subjects operated under normal imaging conditions and 11 with the y-axis inverted. RESULTS: Subjects who operated with the image inverted made significantly more incisions and significantly more correct incisions than those working under normal conditions. This effect persisted over 50 trials. CONCLUSIONS: The fulcrum effect has a major detrimental influence on acquisition of endoscopic skills. Further work is required to investigate the role of image inversion in clinical endoscopic training.

Adult↗
PubMed1998

Mental health expectancy--the European perspective: a synopsis of results presented at the Conference of the European Network for the Calculation of Health Expectancies (Euro-REVES). Medical Research Council Cognitive Function and Ageing Study Group.

The increase in life expectancy observed over the last decade has particular relevance for mental health conditions of old age, such as dementia. Although mental disorders have been estimated to be responsible for 60% of all disabilities, until recently population health indicators such as health expectancies have concentrated on calculating disability-free life expectancy based on physical functioning. In 1994, a European Network for the Calculation of Health Expectancies (Euro-REVES) was established, one of its aims being the development and promotion of mental health expectancies. Such indicators may have an important role in monitoring future changes in the mental health of populations and predicting service needs. This article summarizes the proceedings and recommendations of the first European Conference on Mental Health Expectancy.

Aged↗
PubMed1998

Mental health expectancy: an indicator to bridge the gap between clinical and public health perspectives of population mental health.

Mental health indicators generally used in public health are derived from mortality statistics, but they do not reflect the impact that disability due to mental disorders has on population health. The present study proposes a global indicator of population mental health which combines both mortality and morbidity data. The data used were the results of a Health Interview Survey, including the 12-item version of the General Health Questionnaire, mortality life-tables for the general population, and data from a two-step epidemiological study used to assign the probability of case status. The results are calculated for the Catalonia region in north-east Spain. Life expectancy and mental health expectancies at all ages were found to be higher for women than for men. Men were found to have a higher total life expectancy in good mental health. The feasibility and potential areas of application of this generic mental health index are discussed.

Adolescent↗
PubMed1998

[Early diagnosis of Alzheimer disease].

On of the major challenges for public health in developed countries for the 21st century is that of aging, and in particular Alzheimer's disease. Progress has been made in the development of symptomatic treatment and prevention and early diagnosis of Alzheimer's disease is becoming mandatory. In the present state of our knowledge, no marker for early diagnosis has been described. However, the combined use of clinical observations (behavioral and neuropsychological features) and complementary information (brain morphology and functional imaging, biological data, neurophysiology explorations) could be helpful for early diagnosis of Alzheimer's disease well before the onset of dementia.

Aged↗
PubMed1998

Competence to stand trial: clinician reliability and the role of offense severity.

As research strategies for studying competence to stand trial evolve, interest in the decision-making process of clinicians and the factors that may influence the clinical process has grown. This study assesses the reliability of clinical opinions regarding the basis for competence decisions and the influence that severity of the offense has upon the clinical determinations of competence. One-hundred eighty-eight criminal defendants in an outpatient forensic clinic were evaluated by pairs of clinicians (psychiatrists and clinical psychologists). Each clinician was asked to complete a questionnaire regarding the defendant's overall degree of competence on a 0 to 10 rating scale, ability to understand charges and proceedings and ability to assist in one's defense, and the likelihood that the defendant was malingering. Results demonstrated a high degree of reliability not only in clinical determinations of competence (agreement in 187 of 188 cases), but in estimates of overall degree of competence and the basis for findings of competence or incompetence (e.g., the Dusky criteria). Misdemeanor defendants were more likely to be found incompetent to stand trial. However, degree of competence was only associated with offense severity for defendants found incompetent to stand trial. There was no relationship between these variables for competent defendants. These results suggest that clinicians may require a higher degree of competence for defendants charged with more serious offenses, although this process may not apply equally to competent and incompetent defendants. Furthermore, conducting competence interviews jointly appears to increase the concordance of competence opinions.

Crime↗
PubMed1997

Breast health and associated premenstrual symptoms in women with severe cyclic mastopathy.

OBJECTIVES: A case-control study was undertaken to examine the association of cyclic mastopathy with premenstrual syndrome and prior breast health. STUDY DESIGN: A total of 34 women with severe cyclic mastopathy (cases) and 29 women with no significant breast symptoms (controls) prospectively recorded breast pain and swelling and symptoms of premenstrual syndrome during one menstrual cycle. They also provided information on past breast health. The two study groups were compared by use of standard statistical methods. RESULTS: Women with cyclic mastopathy reported more frequent consultations with physicians for specific breast lumpiness (p = 0.02) or generalized lumpiness (p = 0.004) and for all breast problems (p = 0.0001) and more frequent mammograms (p = 0.04), surgical breast biopsies (p = 0.06), and breast needle aspirations (p = 0.05). Premenstrual symptoms were more severe in women with cyclic mastopathy; this was most pronounced for physical symptoms (water retention and breast symptoms, p < 0.001) but also present for negative affect, behavior change, and impaired concentration (p < 0.05). CONCLUSIONS: Women with cyclic mastopathy have a spectrum of breast concerns and they undergo more frequent breast investigations than do women without the disorder. Most symptoms of premenstrual syndrome are also more severe in women with cyclic mastopathy.

Adolescent↗
PubMed1997

Failed trial of vacuum or forceps--maternal and fetal outcome.

OBJECTIVE: Our purpose was to compare the maternal and neonatal morbidity associated with a failed trial of instrumental delivery with that of proceeding directly to cesarean section during the second stage of labor. STUDY DESIGN: All second-stage cesarean deliveries between January 1986 and December 1992 in a tertiary care teaching hospital were retrospectively reviewed. Specific maternal and neonatal outcome parameters were studied to compare the failed instrumental group with the direct-to-cesarean section group. RESULTS: Of 29,457 live births at > 37 weeks' gestation, 401 women had a cesarean section performed in the second stage of labor. There were 326 cases in which cesarean section was performed directly during the second stage of labor and 75 women who had a failed attempt of instrumental delivery (forceps 33, vacuum 25, both 17) before cesarean delivery was done. The three instrumental groups and the direct-to-cesarean section group did not differ in any of the outcome variables for either mother or newborn. CONCLUSIONS: Failed instrumental delivery performed as a trial of forceps and/or vacuum in a setting where a cesarean section can follow promptly is not associated with increased morbidity of either mother or baby.

Cesarean Section↗
PubMed1997

Dynamic strength of molecular adhesion bonds.

In biology, molecular linkages at, within, and beneath cell interfaces arise mainly from weak noncovalent interactions. These bonds will fail under any level of pulling force if held for sufficient time. Thus, when tested with ultrasensitive force probes, we expect cohesive material strength and strength of adhesion at interfaces to be time- and loading rate-dependent properties. To examine what can be learned from measurements of bond strength, we have extended Kramers' theory for reaction kinetics in liquids to bond dissociation under force and tested the predictions by smart Monte Carlo (Brownian dynamics) simulations of bond rupture. By definition, bond strength is the force that produces the most frequent failure in repeated tests of breakage, i.e., the peak in the distribution of rupture forces. As verified by the simulations, theory shows that bond strength progresses through three dynamic regimes of loading rate. First, bond strength emerges at a critical rate of loading (> or = 0) at which spontaneous dissociation is just frequent enough to keep the distribution peak at zero force. In the slow-loading regime immediately above the critical rate, strength grows as a weak power of loading rate and reflects initial coupling of force to the bonding potential. At higher rates, there is crossover to a fast regime in which strength continues to increase as the logarithm of the loading rate over many decades independent of the type of attraction. Finally, at ultrafast loading rates approaching the domain of molecular dynamics simulations, the bonding potential is quickly overwhelmed by the rapidly increasing force, so that only naked frictional drag on the structure remains to retard separation. Hence, to expose the energy landscape that governs bond strength, molecular adhesion forces must be examined over an enormous span of time scales. However, a significant gap exists between the time domain of force measurements in the laboratory and the extremely fast scale of molecular motions. Using results from a simulation of biotin-avidin bonds (Izrailev, S., S. Stepaniants, M. Balsera, Y. Oono, and K. Schulten. 1997. Molecular dynamics study of unbinding of the avidin-biotin complex. Biophys. J., this issue), we describe how Brownian dynamics can help bridge the gap between molecular dynamics and probe tests.

Avidin↗
PubMed1997

Impact of anesthesia on the cognitive functioning of the elderly.

Exposure to general anesthesia has been suggested as a possible cause of long-term cognitive impairment in elderly subjects. The present study reviews the literature in this field in order to describe postoperative cognitive impairment in elderly populations, to determine to what extent this may be attributed to anesthetic agents, and to consider evidence of a causal relationship between anesthesia and onset of senile dementia. A systematic literature search was conducted using five bibliographic databases (PASCAL, Medline, Excerpta Medica, Psychological Abstracts, and Science Citation Index). Significant cognitive dysfunction was found to be common in elderly persons 1 to 3 days after surgery, but reports of longer-term impairment are inconsistent due to the heterogeneity of the procedures used and populations targeted in such studies. Incidence rates vary widely according to type of surgery, suggesting that factors other than anesthesia explain a significant proportion of the observed variance. Anesthesia appears to be associated with longerterm cognitive disorder and the acceleration of senile dementia, but only in a small number of cases, suggesting the existence of other interacting etiological factors.

Aged↗
PubMed1997

Neuropsychological assessment in Alzheimer's disease: current status and future directions.

Neuropsychological assessment involves the observation and measurement of an individual's behavior in relation to a given stimulus that has been selected for its likelihood to provoke an abnormal response in the presence of neurological damage. This approach incorporates a medical and psychological approach to diagnosis in that both pathology-specific signs and deviations from normal distributions are examined. In the case of Alzheimer's disease (AD), this methodology has assumed considerable importance. This is because behavioral indicators remain the principal basis for provisional diagnosis when there are no biological markers. Observations of elderly persons with and without senile dementia have led to the development of stimuli, or tests, that are able to assess the functioning of specific cognitive processes affected in AD as opposed to more common age-associated changes. Many of these tests have been found to be culturally portable. Diagnostic difficulties arise principally from the fact that many neuropsychological tests cannot be used in isolation, from uncertainty as to the limits of "normal" functioning and from the psychometric problems related to pathological thresholds and item-weighting. The usefulness of neuropsychological testing in the future could undoubtedly be enhanced by the use of measures derived from indices of decline in functioning rather than normative data and the development of functional testing in collaboration with cerebral imaging.

Aged↗
PubMed1997

Evidence that elevated CO2 levels can indirectly increase rhizosphere denitrifier activity.

We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, as determined by a nitrogen mass balance, increased with elevated CO2 levels in the shoot environment and with a high NO3- concentration in the rooting zone. These results indicated that aerial CO2 concentration can play a role in rhizosphere denitrifier activity.

Ammonia↗