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Biomedical subjects

B Kemp

Publications and source records attributed to B Kemp.

At least 181 records · Page 10Linked to original sources
PubMed1986

Simulation of human hypnograms using a Markov chain model.

A Markov chain model has been proposed as a mechanism that generates human sleep stages. A method for estimating the parameters of the model, i.e., the transition probabilities (rates) between sleep stages, has been introduced and applied to 95 hypnograms taken from 23 subjects. The rates characterize interindividual differences and nightly variations of the sleep mechanism, related to sleep-onset behavior, to the decreasing amount of slow wave sleep in the course of the night, and to the REM-NREM periodicity. The model simulates both probabilistic and the above-mentioned predictable dynamics of sleep, but only if these time-varying, individual rates are applied.

Humans↗
PubMed1985

An optimal monitor of the electroencephalographic sigma sleep state.

A model has been proposed for a Markov-jumping sleep depth that modulates a white-noise driven structure generating the sigma rhythm in the electroencephalogram. The corresponding maximum likelihood monitor, that continuously detects the current sleep stage from the observed electroencephalogram, has been derived and implemented. Simulations show high detection performances.

Cybernetics↗
PubMed1985

One-carbon metabolism disturbances in affective disorders. A preliminary report.

Methionine adenosyltransferase (MAT) activity (Vmax) and the relative amount of phosphatidylcholine (% PC) were measured in erythrocytes of up to 30 DSM-III diagnosed manic, 17 unipolar depressed patients, and 28 normal controls. Manic subjects had significantly higher and depressed subjects significantly lower MAT Vmax than normals. The relative amount of PC was in the low range for the depressives, and in the high range for the manics. Depressive patients present, in these tests, similar abnormalities to those seen previously in schizophrenic patients. Clinical and diagnostic implications of these findings are discussed.

Bipolar Disorder↗
PubMed1985

Decreasing the burden in families caring for a relative with a dementing illness. A controlled study.

The purpose of this study was to investigate the efficacy of a specifically designed group support program for relatives of patients with Alzheimer's disease and related disorders. The group program included educational/supportive activities and used basic principles of the cognitive-behavioral approach. Twenty-two subjects participated in an eight-session program. Eighteen control subjects received no treatment. Measures of family burden, levels of depression, and knowledge of dementia were obtained. Experimental subjects showed a significant decrease in total family burden, whereas control subjects actually showed a significant increase, experimental subjects also showed reduction in their levels of depression. Experimental subjects showed a significantly greater improvement than did control subjects on knowledge of dementia. The acquisition of new knowledge was an important ingredient in reducing perception of burden and levels of depression, but other facets of the intervention also accounted for the improvement. Results indicated that a relatively short but intensive support experience can have a positive effect in reducing some of the burden and depression associated with the care of a demented relative.

Adolescent↗
PubMed1985

The flexor carpi radialis H-reflex in lesions of the sixth and seventh cervical nerve roots.

In 143 normal subjects latencies of H-reflexes of the flexor carpi radialis muscle were well correlated with arm lengths. In 32 patients with injury to cervical roots C5 to C8 it was shown that latencies were only abnormal in lesions of roots C6 or C7. It is suggested that in most instances root C6 or C7 and, probably both roots in some cases are involved in the reflex pathway. Repeat electrophysiological examinations after surgery provided valuable data about the various types of nerve root recovery.

Adult↗
PubMed1985

Vocational rehabilitation of the older worker.

Work is an important social role. A disability can interfere with a person's work abilities and opportunities at any age. Unfortunately, the older population has received disproportionately little attention in rehabilitation, particularly in vocational rehabilitation. This is true, in spite of the fact that there is a growing population of older persons, with a high prevalence of disability. When returning an older disabled person to work, consideration of his or her particular physical, psychological, and social characteristics is required. This paper discusses the involvement of occupational therapists in the returning of older persons to work.

Aged↗
PubMed1984

Health needs of the Hispanic elderly.

This paper presents results of a study concerning the health care needs of the Hispanic elderly population of Los Angeles County. By use of the Comprehensive Assessment and Referral Evaluation (CARE) instrument, data on a sample of 704 subjects were employed to compute the scores for 22 Likert-type scales measuring the prevalence of numerous psychiatric, medical, and social problems. The data indicate that older Hispanics were affected by cognitive impairment (13.8 per cent), depression/demoralization (30.8 per cent), heart disorders (12.8 per cent), stroke effects (11.5 per cent), arthritis (28.3 per cent), hypertension (23.7 per cent), financial hardship (28.0 per cent), fear of crime (38.4 per cent), ambulation problems (17.2 per cent), or activity limitation (24.7 per cent); they also needed assistance (19.3 per cent) or used social services (22.0 per cent). Further analysis revealed that the prevalence of many of these problems varies significantly according to the age, sex, language, and income of respondents. The indicators of health care needs used in the study differed substantially from the more traditional measures based on the person's own perception of his or her health.

Aged↗
PubMed1984

Use of health care services by older Hispanics.

This paper presents information on regarding older Hispanics' use of health care services in an urban setting. Using the Comprehensive Assessment and Referral Evaluation (CARE) questionnaire, data on patterns of health care use and correlates of health services utilization were collected from a sample of 704 Hispanics age 60 and over residing in Los Angeles County. The results indicate that during the year preceding the interview, 79.4 per cent of the respondents saw a physician and 10 per cent were hospitalized. Of those seeing a doctor, 83.5 per cent saw a general practitioner and 32.6 per cent a specialist. When requiring medical care, respondents said that they would go to local private doctors (49.9%), hospitals (26.7%), neighborhood clinics (18.6%), and Mexico (2%). Further analysis revealed that some utilization measures varied significantly according to respondents' sociodemographic and economic correlates such as age, language, income, and availability of health insurance.

Aged↗
PubMed1983

Accurate measurement of flash-evoked alpha attenuation.

An accurate method for measuring flash evoked alpha attenuation has been derived, based on a model of the alpha generator. The method has been applied to 10 healthy volunteers in order to determine their alpha attenuation latencies (AALs). For the 9 subjects which showed at least some alpha rhythm, the AAL group mean is 95 msec. The AAL inaccuracy (S.D. 5 msec) is smaller than interindividual differences (S.D. 13 msec). There exists no relationship between the AAL and the frequency of the alpha rhythm.

Adult↗
PubMed1982

Ulnar F-wave conduction velocity in epidural metastatic root lesions.

In 40 controls and 19 patients with neoplastic lesions of the eighth cervical and first thoracic nerve roots confirmed by myelography, ulnar F-wave conduction velocity (FWCV) was estimated using the shortest F-wave latency (FWL). F-waves were recorded from needle electrodes inserted in the abductor digiti minimi manus muscle after stimulation of the ulnar nerve at the wrist. Motor nerve conduction velocities of distal ulnar segments were normal. It was found that the ulnar FWCV decreases significantly with increasing age. This is not true for FWL. During the initial examinations ulnar FWCV was delayed in 18 patients. At follow-up, ulnar signs correlated well with changes in FWCV. Low F-wave frequency and wide FWL differences are also important features in ulnar root disease.

Adolescent↗
PubMed1982

Tiapride in the treatment of tardive dyskinesia.

The effect of Tiapride on dyskinesia was evaluated in 12 patients with tardive dyskinesia in a double-blind controlled cross-over trial. The effect was measured by a Doppler-radar device and by counting the number of involuntary movements from video-recordings. Besides these methods, subjective assessments were made on analogue scales by family, nurses and attendant doctors. The subjective evaluation appeared to be useless because of many inconsistent answers. The quantitative methods revealed a significant diminution of the involuntary movements in the Tiapride therapy period (P less than 0.01). It appears that tiapride is an effective drug in the treatment of tardive dyskinesia. No clinically important side-effects have been observed. The drug appeared not to induce parkinsonism.

Adult↗
PubMed1982

Tiapride in the treatment of Huntington's chorea.

Twenty-two patients with Huntington's chorea were investigated in a double-blind controlled cross-over trial. The effect was measured by counting the number of involuntary movements from video-recordings and by a Doppler-radar device. Besides these methods, subjective assessments were made on analogue scales by patients, family, nurses and attendant doctors. The quantitative methods revealed no significant diminution of the involuntary movements in the Tiapride therapy period. The subjective evaluation turned out to be useless because of many inconsistent answers.

Adult↗
PubMed1981

Optimal detection of the alpha state in a model of the human electroencephalogram.

A mole of the EEG with waxing, waning and blocking alpha rhythm is described. One parameter is time dependent and simulates the "physiological alpha state' of the EEG generating network. A theoretically optimal detector of this state appears to be prescribed by the model and the statistics of the alpha state parameter. It minimizes the expected false decision rate.

Alpha Rhythm↗
PubMed1979

Auditory brainstem evoked responses in brainstem compression due to posterior fossa tumors.

Five patients with unilateral posterior fossa tumors were investigated with Auditory Brainstem Evoked Responses (B.E.R.). The B.E.R., recorded from the ear ipsilateral to the tumor, were consistent with a lesion of the acoustic nerve or the cochlear nuclei in all patients. The contralaterally evoked responses in four patients with large tumors and radiological signs of brainstem compression showed normal latencies and amplitudes of the first three waves, while waves IV and V were definitely abnormal with respect to amplitudes and latencies. (The 4th patient had a normal wave IV and a delayed, small wave V). In one patient with a relatively small acoustic neurinoma the contralateral B.E.R. were normal. It is concluded that the upper pontine and lower midbrain level, presumed sites of generation of wave IV and V of the B.E.R., are more susceptible to brainstem compression due to unilateral posterior fossa tumors, than the lower parts of the brainstem.

Adult↗
PubMed1978

[Influence of uncorrelated noise sources in parallel signal processing chains on the coherence function (author's transl)].

When linear relationships between bio-electrical signals have to be established, it is important to consider the possible influence of noise added to these signals during recording and processing. Using a model for the signal generation (Fig. 1A) and one for the signal processing (Fig. 1B), the influence of uncorrelated noise in parallel signal processing chains on the coherence function can be quantified (Fig. 2). This is illustrated by the results of electrophysiological experiments, in which field potentials have been recorded simultaneously by two electrodes in different parts of the rat brain.

Animals↗
PubMedDate not supplied

Vasopressin antisense peptide interactions with the V1 receptor.

The molecular recognition hypothesis, that peptide ligands and their receptor binding sites are encoded by complementary nucleotide sequences, was tested for arginine vasopressin (AVP) and its V1 receptor. Binding of [125I] [d(CH2)5,Sar7]AVP (a selective V1 vasopressin antagonist radioligand) or [3H]AVP to rat liver plasma membranes was inhibited by peptides known to bind to V1 receptors but not by the AVP complementary peptide (Ser-Ser-Trp-Ala-Val-Leu-Glu-Val-Ala) (PVA). Rabbit anti-PVA antibodies were nonimmunoreactive with any protein in rat liver membranes or in a partially purified preparation from rat liver containing reconstitutable vasopressin binding activity. Furthermore, there was no suppression of the AVP pressor effect by PVA in vivo using a rat blood pressure bioassay. These findings do not support the hypothesis that the V1 receptor binding site is encoded by the antisense DNA strand to AVP.

Amino Acid Sequence↗