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Biomedical subjects

L Adamson

Publications and source records attributed to L Adamson.

At least 37 records · Page 2Linked to original sources
PubMed1985

Factor XIII catalyzed formation of fibrinogen-fibronectin oligomers--a thiol enhanced process.

Fibrinogen and plasma fibronectin were shown to interact in the presence of factor XIIIa. The reaction was enhanced by dithiothreitol and was accompanied by an increase in the turbidity of the solution and the formation of particulate matter and gel structures. At a constant concentration of fibrinogen the turbidity increase was dependent on the fibronectin concentration and at a constant concentration of fibronectin, on the fibrinogen concentration. Kinetic experiments showed that an initial step in the reaction between fibrinogen and fibronectin was the formation of a transient intermediate containing 1 mole of fibrinogen and 1 mole of fibronectin. Transient intermediates of larger molecular weight and containing both fibrinogen and fibronectin were also formed. These heterooligomers eventually reached huge molecular sizes and at early times formed particulate matter that sedimented on centrifugation. The predominant molecular species formed in an equimolar mixture of fibrinogen and fibronectin were heteropolymers. Small amounts of homopolymers composed of fibrinogen and possibly also homopolymers of fibronectin were detected. The results are discussed in terms of reaction mechanism and potential importance of this novel oligomerization pathway in haemostasis, thrombosis and tissue repair.

Dithiothreitol↗
PubMed1985

FXIII induced gelation of human fibrinogen--an alternative thiol enhanced, thrombin independent pathway.

Factor XIII induced gelation of human fibrinogen in the presence of calcium ions. At the end of this reaction between 95 and 100% of the fibrinogen was incorporated into the gel matrix. The gelation was dramatically enhanced by DTT. Cysteine and beta-mercaptoethanol also enhanced the reaction, but less efficiently. Thrombin activated factor XIII led to shortened gelation time and increased the rate of gelation. The reaction was inhibited by p-chloromercuribenzoate and iodoacetamide. Neither fibrinopeptide A, nor fibrinopeptide B were released during gelation, while quantitative release of FPA by thrombin was demonstrated from preformed gel matrices. SDS-PAGE showed the presence of gamma-dimers and alpha-polymers in the gel matrix. In the clot supernatants gamma-dimers were observed already before the gel point. We also observed that the clotting of fibrinogen by thrombin was perturbed by DTT. Preincubation of fibrinogen with calcium ions prevented this effect of DTT.

Calcium↗
PubMed1984

Effect of intravenous glucose injection on human maternal and fetal heart rate at term.

The effects of maternal intravenous glucose administration (25 gm) on maternal heart rate, fetal heart rate, gross fetal body movements, and fetal heart rate accelerations was measured in 11 healthy pregnant women at 38 to 40 weeks' gestational age. Mean maternal heart rate increased from 78.3 +/- 0.8 bpm during the control period to 82.7 +/- 0.5 bpm at 30 to 85 minutes following glucose injections (p less than 0.01). Mean fetal heart rate rose from 137.8 +/- 0.4 bpm to 142.4 +/- 0.3 bpm at 50 to 95 minutes following injections (p less than 0.001). The incidence of gross fetal body movements and the number, duration, and amplitude of fetal heart rate accelerations did not change following glucose injection. We conclude that maternal glucose administration near term results in a small but significant increase in the mean maternal heart rate and fetal heart rate and no change in the incidence of gross fetal body movements or in fetal heart rate accelerations.

Blood Glucose↗
PubMed1982

Effects of intravenous glucose injections on human fetal breathing movements and gross fetal body movements at 38 to 40 weeks' gestational age.

Fetal breathing movements and gross fetal body movements were studied subsequent to the intravenous injection of either 25 gm of glucose or an equal volume of normal saline solution in 10 healthy women with uncomplicated pregnancies at 38 to 40 weeks' gestation. The incidence of fetal breathing increased from 17.5% during the control period to 54.9% after glucose injection. Neither glucose nor saline solution had any effect on the incidence of gross fetal body movements. All fetuses made some breathing movements during any 15-minute interval between 30 and 75 minutes after glucose injection. These data suggest a useful strategy for clinical measurement of fetal breathing activity near term.

Apgar Score↗
PubMed1976

Nitrazepam: lastingly effective but trouble on withdrawal.

The sleep of 10 volunteers with an average age of 57 years was recorded electrophysiologically before, during, and after nitrazepam 5 mg nightly for 10 weeks. Sleep was longer and less broken on the drug and no tolerance was obvious after two months' use. Withdrawal of the drug, however, caused sleep to be temporarily worse than before the drug had been taken. Slow-wave sleep was reduced by nitrazepam, but the accompanying secretion of growth hormone was not impaired.

Adult↗
PubMed1976

Do placebos alter sleep?

Deliberate suggestion that an inert capsule was a sleeping pill was found not to influence subjective ratings of sleep quality or anxiety or the electrophysiologically recorded features of sleep in 10 volunteers aged 41-62 years.

Adult↗
PubMed1976

The behavior of the full-term but underweight newborn infant.

Ten underweight full-term newborns were compared with 10 full-weight newborns on the Brazelton Neonatal Behavioral Assessment Scale. The Brazelton examination differentiated the two groups clearly on the reflexes of walking, crawling and passive movements of arms and legs, and on rooting and sucking. More importantly, it differentiated the two groups on behaviors which are important for the caretaker of the baby: these are attractiveness, need for stimulation, interactive processes and motor processes. The 10 underweight infants were followed up at a later date during the first year. They showed temperamental organizational difficulties and some indication of psychosomatic reaction to stress. It is possible that the underweight newborn's fragile organization elicits anxiety in the caretaker which makes interaction difficult.

Child Behavior↗
PubMed1976

Regional obstetric anesthesia and newborn behavior: effect over the first ten days of life.

This study examined the effects of carefully controlled amounts of analgesic premedications and anesthetics administered to mothers during delivery on the behavior of the newborn over the first ten days of life. The subjects were selected to minimize the synergistic effects of medication and other stress factors, such as abnormalities of pregnancy, labor, or delivery. The effects of these drugs on the behavior of these infants was small. The data provide a picture of the behavioral recovery of a group of minimally stressed newborns.

Adult↗
PubMed1975

Early mother-infant reciprocity.

By three weeks of age, the human neonate demonstrates behaviours which are quite different with an object and with a human interactant. He also demonstrates an expectancy for interaction with his caregiver which has clearly defined limits, as demonstrated behaviourally. In microanalysis of videotape, we saw regularly a set of interactive behaviours which were demonstrable in optimal face-to-face interaction between infants and their mothers. All parts of the infant's body move in smooth circular patterns as he attends to her. His face-to-face attention to her is rhythmic with approach-withdrawal cycling of extremities. The attention phase and build-up to her cues are followed by turning away and a recovery phase in a rhythm of attention-non-attention which seems to define a cyclical homeostatic curve of attention, averaging several cycles per minute. When she violates his expectancy for rhythmic interaction by presenting a still, unresponsive face to him, he becomes visibly concerned, his movements become jerky, he averts his face, then attempts to draw her into interaction. When repeated attempts fail, he finally withdraws into an attitude of helplessness, face averted, body curled up and motionless. If she returns to her usual interactive responses, he comes alive after an initial puzzled period, and returns to his rhythmic cyclical behaviour which has previously characterized their ongoing face-to-face interaction. This attentional cycling may be diagnostic of optimal mother-infant interactions and seems not to be present in more disturbed interactions.

Attention↗
PubMed1973

Two anti-anxiety drugs: a psychoneuroendocrine study.

Eight males were studied during 27 weeks, including two periods of five weeks during which they received clinical doses of sodium amylobarbitone and benzoctamine. Substitution of placebo for either drug caused raised anxiety and impairment of mental concentration. The drugs reduced restlessness during sleep and reduced paradoxical sleep. By the fifth week of sodium amylobarbitone, although sleep was still less restless in the early night it was more restless than normal in the late night.Blood samples were taken half-hourly during sleep by indwelling venous catheter. Plasma growth hormone concentration was little affected during drug administration but rose temporarily after withdrawal. There was a reduction of plasma corticosteroid concentration during sleep throughout administration of the drugs and a rebound above normal during the first withdrawal week.

Adrenal Cortex Hormones↗