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Biomedical subjects

O Ostberg

Publications and source records attributed to O Ostberg.

12 recordsLinked to original sources
PubMed2003

Quantification of ADP and ATP receptor expression in human platelets.

The mechanism of ADP-mediated platelet activation has been difficult to unravel due to the large number of receptors for extracellular nucleotides (P2 receptors). mRNA levels in circulating platelets are very low, but have been shown to be translationally active. By optimizing mRNA extraction and using real time (RT)-PCR we were able to establish a protocol for highly sensitive platelet mRNA quantification in human regular blood samples. In platelets from healthy volunteers, only P2X1, P2Y1 and P2Y12 were found in significant levels, with the following order of expression: P2Y12 >> P2X1 > P2Y1. Other P2 receptors (P2Y2, P2Y4, P2Y6, P2Y11, P2Y13, P2X4, P2X7) had very low expression. As a control measurement to exclude contamination, P2 receptors in buffy coat were quantified but had a completely different profile. Incubation in vitro revealed a more rapid degradation rate for P2X1 receptor mRNA than for P2Y1 and P2Y12, indicating that the level of P2X1 may be relatively higher in newly released platelets and in megacaryocytes. In conclusion, we have developed the first protocol for quantifying mRNA expression in human platelets limiting the P2 receptor drug development targets to P2Y12, P2Y1 and P2X1. Furthermore, the method could be used to study platelet expression for any gene in human materials.

Base Sequence↗
PubMed1994

MTFA templates for quick and inexpensive assessment of display image resolution.

Traditional MTFA measurements are time-consuming, expensive and cumbersome. This situation was a hindrance in the authors' work on the evaluation of the merits of MTFA as a measure of display screen image quality. A set of hard-copy MTFA templates was therefore designed to constitute an intervening variable suitable for quick quality assessments by experimental subjects. This intervening scale worked quite satisfactorily, and the present paper reports how it has been turned into an independent tool for the assessment of display image resolution.

Journal Article↗
PubMed1992

On the merits of ancient Chinese eye acupressure practices.

Chinese schoolchildren and adults with strenuous visual tasks routinely perform massage-and-pressure exercises on selected acupressure points around the eyes. This practice, taught by the Jing-Luo school of acupuncture for more than 4000 years, is claimed to prevent and cure myopia and other afflictions thought to result from visual close work. A four-week pilot experiment was carried out with the aim of designing a proper study on the possible short-term benefits of eye acupressure programmes. Questionnaire data revealed that the subjects did experience various eye/vision symptoms as a result of the 90 min experimental task. This could not be verified by the measurements of accommodation precision and critical flicker fusion, nor could any beneficial effects of acupressure be seen over the four experimental weeks.

Journal Article↗
PubMed1977

Individual differences in human circadian rhythms.

Research into individual differences in circadian rhythms is reviewed, particularly morningness-eveningness. It was hypothesised that extraverts would be inclined towards eveningness and introverts towards morningness. Forty-eight subjects took regularly their oral temperature. Peak times were identified from smoothed temperature curves. Results showed that extraverts had a peak time insignificantly later than introverts. Re-grouping of the data into the morningness-eveningness dimension, based upon the results of a self assessment questionnaire, showed that evening types had significantly later peak times than morning types. Morningness-eveningness was not significantly ocrrelated with extraversion-introversion, although there was a trend. No significant differences were found for sleep lengths with either groupings, or for sleep-wake habits within extraversion-introversion. Morning types retired and arose significantly earlier than evening types. Although sleep-wake habits and extraversion-introversion help to determine peak times there are other contributory factors to peak time which appear to be partly covered by the questionnaire.

Adolescent↗
PubMed1976

A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms.

An English language self-assessment Morningness-Eveningness questionnaire is presented and evaluated against individual differences in the circadian vatiation of oral temperature. 48 subjects falling into Morning, Evening and Intermediate type categories regularly took their temperature. Circadian peak time were identified from the smoothed temperature curves of each subject. Results showed that Morning types and a significantly earlier peak time than Evening types and tended to have a higher daytime temperature and lower post peak temperature. The Intermediate type had temperatures between those of the other groups. Although no significant differences in sleep lengths were found between the three types, Morning types retired and arose significantly earlier than Evening types. Whilst these time significatly correlated with peak time, the questionnaire showed a higher peak time correlation. Although sleep habits are an important déterminant of peak time there are other contibutory factors, and these appear to be partly covered by the questionnaire. Although the questionnaire appears to be valid, further evaluation using a wider subject population is required.

Adolescent↗
PubMed1975

Time of day effects on extroversion and salivation.

A circadian rhythm in the biological basis of extroversion-introversion (E-I) was hypothesized. Eighty subjects had their EPI E-I scores and lemon juice test (LJT) scores assessed at a.m. and at p.m. Results showed that : (a) there were high intra-test correlations for EPI E-I and LJT; (b) a significant correlation between EPI E-I and LJT was only found for a.m. and not for p.m.; and (c) there were large individual differences in LJT scores. It was concluded that a circadian rhythm of E-I could not be detected by these measures, and that applicability of the LJT to E-I depends upon the time of day of assessment and the measurement procedure employed.

Adolescent↗