PubMed Health⌕ Search

Biomedical subjects

A L Evans

Publications and source records attributed to A L Evans.

At least 19 recordsLinked to original sources
PubMed1995

Gait speed and activities of daily living function in geriatric patients.

OBJECTIVE: To establish the relationship between gait speed (GS) and functional independence in elderly people. DESIGN: GS is suggested as being a criterion standard in rehabilitation reflecting muscle strength. This study assessed the relationship between gait speed and functional independence in Activities of Daily Living (ADL). GS was measured by portable accelerometer over 2 meters. The mean of 3 attempts was taken. ADL function was measured by an occupational therapist using the modified Barthel ADL Index. The relationship between these measures was assessed by a statistician. SETTING: A geriatric unit in a hospital in Scotland. PATIENTS: One hundred sixty-one inpatients and outpatients were selected at random from the patients of a geriatric unit over a 3-month period. Patients were eligible if they were mobile with or without a walking aid. INTERVENTIONS: GS was measured by portable ultrasonic accelerometer. Patients were reviewed by an occupational therapist, blinded to their GS, who recorded functional capacity. Case sheet review provided diagnostic details and cognitive function. The type of floor surface was recorded. MAIN OUTCOME MEASURES: GS (m/sec), and Barthel score. RESULTS: Patients with GS of < .25m/sec were more likely to be dependent in one or more ADL function, p < .01. Those with a GS between .35 and .55m/sec were more likely to be independent in all ADL functions, p < .001. Patients whose GS was > .55m/sec did not maintain this independence. There was no relationship between GS and floor surface or cognitive function. CONCLUSIONS: GS is a useful indicator of ADL function in geriatric patients.

Activities of Daily Living↗
PubMed1994

The measurement of steady-state visual evoked cortical potentials using an adaptive noise canceller.

A new software method for measuring steady-state visual evoked cortical potentials (VECPs) has been developed using the principle of adaptive noise cancelling. The steady-state VECP is composed of narrow-band frequency components at harmonics of the stimulus frequency. In clinical recordings, these signal components are masked by wide-band noise, predominantly electroencephalographic activity and muscle noise. The stimulus frequency is exactly known and by using a reference sinusoid at the stimulus frequency (or its harmonics) the adaptive noise canceller (ANC) is able to cancel uncorrelated noise components from the recording. In effect, the ANC functions as an adaptive narrow-band-pass filter at the reference frequency. The performance of the ANC has been evaluated using both simulated and physiological signals. The output of the ANC provides temporal information on the signal amplitude and phase, and can be used to calculate the reliability of signal detection. For this application, the ANC has a number of advantages over the fast Fourier transform: it is a more sensitive detector, it requires fewer calculations, it is less computationally intensive, it requires less memory and it can be implemented in real time.

Algorithms↗
PubMed1992

Characterisation and correction of a mammalian cell mutant defective in late step of base excision repair.

An Indian muntjac cell line, SVM, is unusually sensitive to cell killing induced by a range of alkylating agents. Cells transfected with the Escherichia coli ada gene or human genomic DNA have allowed the response of SVM to alkylating agents to be dissociated into two distinct components. Thus, in SVM, which expresses very low levels of alkyltransferase (AT), O6-alkylguanine appears to be the major cytotoxic, clastogenic, and recombinogenic lesion following exposure to agents such as methylnitrosourea (MNU). However, SVM is also very sensitive to agents such as dimethylsulfate (DMS), which produce only very low levels of O6-methylguanine damage. Sensitivity to DMS resides in an inability to complete base excision repair, with the appearance of persistent single-strand DNA breaks (SSBs), and does not appear to involve defects in glycosylase, apurinic/apyrimidinic endonuclease, or DNA ligase activities. Another, possibly related, phenotypic trait in SVM is its limited ability to ligate transfected linear plasmid DNA. Transfectants of SVM, harboring human DNA sequences, show a significant correction of DMS-induced cytotoxicity and clastogenicity and a reduction in the levels of DMS-induced DNA SSBs. The DMS-resistant transfectants have an increased ability to ligate linear plasmid DNA, and also express AT, making these lines resistant to alkylating agents such as MNU. These results suggest that cells possess a mechanism that regulates AT expression, plasmid break-joining ability, and certain aspects of base excision repair. Transfectants of SVM containing human DNA provide a means to isolate genes involved in a coordinate response to alkylation damage.

Alkylating Agents↗
PubMed1991

Cutaneomuscular reflexes recorded from the first dorsal interosseous muscle of children with cerebral palsy.

Cutaneomuscular reflexes were recorded from the first dorsal interosseous muscles of 21 children with spastic cerebral palsy. The reflex responses in children with cerebral palsy were consistent with dysfunction of the pyramidal system, but differed from those seen in adults with central nervous lesions. This provides further evidence that the effect of a central nervous lesion on the reflex control of movement is dependent on whether it occurs in early or adult life.

Adolescent↗
PubMed1991

Effect of cooling rate on leucite volume fraction in dental porcelains.

Prasad et al. (1988) have shown that slow cooling of dental porcelain produces increases in thermal expansion sufficient to make a compatible metal-porcelain system incompatible. The present study was undertaken to determine whether the increase in porcelain thermal expansion might be attributable to crystallization of additional leucite during slow cooling of the porcelain. Eight x-ray diffraction specimens for each of six commercial dental porcelains and for the Component No. 1 frit of the Weinstein and Weinstein (1962) and Weinstein et al. (1962) patents were fabricated and divided into two groups. Specimens in the first group (termed fast-cooled) were cooled in the conventional manner by removing them from the furnace at the maximum firing temperature immediately into room air. Specimens in the second group (termed slow-cooled) were cooled slowly by interrupting power to the furnace muffle and allowing them to cool inside the closed furnace. Quantitative x-ray diffraction was performed on the fast- and slow-cooled porcelain specimens with standards containing leucite volume fractions of 0.111, 0.223, 0.334, and 0.445. Unpaired, one-tailed t tests were performed on the fast- and slow-cool data, and a significant increase (p less than 0.05) in the amount of leucite (as a function of the slow cooling) was found for each of the porcelains. The increases in the leucite volume fractions resulting from the slow cooling ranged from a low of 8.5% to a high of 55.8%, with an average increase of 26.9%.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum Compounds↗
PubMed1991

Color changes in post-cure heat-treated resin composites.

The purpose of this study was to determine the color changes that arise from post-cure heat treatment of selected light-cured resin composites by using colorimetric as well as observational methods. Brands of composite were selected that were solely Bis-GMA-based and Bis-GMA/urethane based. These materials also represented a range of filler content (low, medium, and high). The RGB values of cured resin discs were obtained immediately after light-curing as well as after a 5-minute post-cure heat exposure. The range of post-cure temperature was from 100-300 degrees C in 25 degrees C increments. The mean delta L*, delta a*, delta b* and delta E* were determined from red, green and blue data using triplicate replications for each heating condition. Twenty-one observers were asked to determine if the randomly arranged post-cure heated specimens differed in color from the unheated, cured control specimen for each brand. The results indicate that a delta E* value of approximately 3 resulted in greater than 50% of the observers noting a color difference between the post-cure heated specimen and the unheated control. The degree of color change was influenced more by the amount of resin content in the composite systems rather than by the particular resin composition. Microfill resins showed greater potential for color change than did the other types of materials. If clinicians are considering using conventional light-cured composite materials for inlays, the choice of material as well as the post-cure temperature will influence the ability to match the inlay with the original shade of composite selected.

Analysis of Variance↗
PubMed1990

Maturation of the cutaneomuscular reflex recorded from the first dorsal interosseous muscle in man.

1. Cutaneous reflexes have been recorded from the first dorsal interosseous muscle following electrical stimulation of the digital nerves of the index finger in man. Recordings have been obtained from 127 children, aged from 3 to 18 years while each performed an isometric abduction of the index finger and whole hand grips. 2. In the adult, reflexes recorded while subjects performed an isometric abduction of the index finger consisted of three readily identifiable components within the first 100 ms. These were an initial short spinal latency increase in EMG (E1), followed by a decrease (I1), followed by a prominent longer-latency increase (E2) which was normally larger in size than the shorter-latency increase. 3. The configuration of the reflex changed during development. When recorded during an abduction, the E1 component was present in all children and showed a small but progressive reduction in size with age. With increasing age, both the I1 and E2 components were present in an increasing proportion of children and increased in size until the adult configuration was reached at 14-15 years. 4. Comparison of reflexes recorded during sustained whole hand grips with reflexes recorded during an isometric index finger abduction revealed differences in all three components. When recorded during those grips used in the present study the E1 component was generally significantly larger while the I1 component was generally significantly smaller than when recorded during index finger abduction. At all ages the E2 component was significantly smaller when recorded during a grip. 5. The configuration of the reflex during an isometric index finger abduction was compared with the ability of the child to perform rapid finger movements. Those children who had no E2 component tended not to perform well in the tests of rapid finger movement. However, there was no simple relationship between the size of the E2 component and ability to produce rapid finger movements.

Adolescent↗
PubMed1990

Dreams and suicidal behaviour.

Oneirology, the study and interpretation of dream content, has been part of human experience throughout recorded history. In modern times, the interpretation of dreams has been used as a tool in the practice of psychotherapy for the purpose of developing insight into the individual's intrapsychic and interpersonal relationships. Ringel, Jung, and others have noted that the content of dreams may be used to assess the individual's state of mind with regard to suicidal intent. Litman has noted the difference between dreams related to suicide and dreams expressing the presence of a clinical depression. Death dreams of the elderly may be considered expressions of depressive symptoms, although this conclusion should be approached with caution. Taylor, Sanford, and others have noted that death dreams generally may be considered as the need for transformation within the individual's personality. The author's impressions taken from clinical experience as well as his experience in teaching university-level courses both in dream interpretation and suicidology are also included in this paper.

Depressive Disorder↗
PubMed1989

The Pocket Speech Aid.

A rapid-access but limited vocabulary communication aid for the non-vocal and speech impaired is useful in some well defined situations. The design and construction of such a device is described. Three distinct situations have been identified where an aid is essential and an initial evaluation has shown the Pocket Speech Aid to be very successful.

Biomedical Engineering↗
PubMed1989

Task-dependent changes in cutaneous reflexes recorded from various muscles controlling finger movement in man.

1. Cutaneous reflex responses have been recorded from muscles involved in the control of finger movement following electrical stimulation of the digital nerves of the fingers in man. 2. Recordings have been made while subjects performed various manual tasks. 3. Reflexes recorded while subjects performed a relatively isolated finger movement consisted of an initial short-latency increase in muscle electrical activity, followed by a decrease, followed by a prominent longer-latency increase. The long-latency excitatory component was smaller or absent during those grips used in the present study. 4. The short-latency excitatory (E1) and inhibitory (I1) components of the cutaneomuscular reflex response are mediated via spinal pathways. The second longer-latency excitatory component (E2) is of supraspinal origin, requiring the integrity of the dorsal columns, sensorimotor cortex and corticospinal tract (Jenner & Stephens, 1982). The results of the present study suggest that one or more of these supraspinal pathways is more active when a finger is used in a relatively isolated manner than when the same finger participates in any of the gripping manoeuvres used in the present experiments.

Adolescent↗
PubMed1988

The functional testing of external cardiac pacemakers.

In common with all other biomedical equipment, cardiac pacemakers should be routinely tested and serviced. Experience has shown that although they are generally very reliable some faults have occurred that might have been detected by regular testing. A testing protocol is suggested that has two levels, routine tests that check the essential functions of the pacemakers and supplementary tests that check those parameters which are less likely to be of immediate clinical significance. The measurement details and rationale of the tests are described in some detail. Finally, a preliminary evaluation of a test instrument which has been developed specifically for these procedures shows that it is rapid and easy to use and allows a more rigorous standard of testing to be achieved.

Equipment Failure↗