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Biomedical subjects

G Graham

Publications and source records attributed to G Graham.

At least 91 records · Page 5Linked to original sources
PubMed1980

Age-related differences for motion sickness in the rat.

The relationship between motion sickness and age was examined in three groups of male rats in order to determine whether or not age related differences in susceptibility are due to experiential factors or unspecified changes in the central nervous system. The results revealed no difference in susceptibility between 2-month old and 11-month old group. However, the 20-month old group was significantly less susceptible to motion sickness than either of the other groups. These findings indicate that general age related changes in the central nervous system are more likely to account for the relationship between motion sickness and age tha are experiential factors.

Aging↗
PubMed1980

Performance of a radiometer transcutaneous oxygen monitor in a neonatal-intensive-care unit.

We evaluated the performance of the Radiometer TCM-1 Transcutaneous Oxygen Monitor in a Class III neonatal-intensive-care unit during an 11-month clinical trial (in excess of 4000 h) in which we monitored 115 infants ranging in gestational age from 25 to 43 weeks and in birthweight from 595 to 4220 g. In vitro transcutaneous partial pressure of oxygen (ptcO2) measurements were accurate within 1% of the theoretical value and precise (1.4% CV at 156 mmHg) at 44 degrees C. Determinations at other temperature were less accurate except in rare instances when specific patient-associated ptcO2/paO2 bias was identified. In vitro comparison of ptcO2 (y) and arterial partial pressure of oxygen (paO2) (x) measurements agreed well (y = 0.90x + 6.9, r = 0.94) except when infants were less than 24 h old. In this latter group the ptcO2/paO2 ratio usually exceeded 1.0 and fluctuated unpredictably. ptcO2 measurements on infants less than 24 h old had to be interpreted cautiously. In general, the ptcO2 and paO2 measurements agreed sufficiently well for the physicians to use them as the basis for directing patient care.

Age Factors↗
PubMed1980

Commercially available blood-gas quality controls compared with tonometered blood.

We compared three commercially supplied blood-gas quality control solutions ("contrIL," "G.A.S.," and "Quantra") and tonometered whole blood under research and service conditions in four hospital laboratories. In some situations Quantra and tonometered blood were comparably sensitive to problems with blood-gas instrument malfunctions (e.g., hydraulics or temperature control) but the aqueous buffer-based materials were less sensitive. Within-day precision for all control materials was similar. The precision of pCO2 determinations in long-term studies was also similar for all control materials, as were pH determinations on commercial controls. For pO2 (especially at O2 < 50 mmHg), sample handling technique influenced the precision and accuracy of Quantra more than the other materials. The variability in pO2 determination with Quantra seems primarily to result from sensitivity in incubation temperature (3% change per degree C at 145 mmHg and 7% change per degree C at 43 mmHg). This study identifies some of the limitations of blood-gas control materials per se and some limitations related to specific blood-gas instruments that affect interpretation of results from them.

Blood Gas Analysis↗
PubMed1980

Changes in transcutaneous oxygen tension during capillary blood-gas sampling.

With a Radiometer TCM-1 oxygen monitor, we followed the fluctuations in transcutaneous oxygen tension (ptcO2) during capillary blood collection from a heel prick. Thirty premature infants who presented with some respiratory compromise showed unpredictably increased (43 of 125 observations) or decreased (82 of 125 observations) values during this blood-sampling process. The fluctuation exceeded 10 mmHg in 61 observations and represented as much as -67% relative change. In general, ptcO2 values exceeded capillary pO2 values determined by standard blood-gas analysis. We investigated several aspects of capillary blood sampling to explain these observations. Because the induced response is a dynamic change, which continues throughout the collection process, we conclude that successive specimens will have different O2 tensions. Even if the capillary blood pO2 truly reflected paO2, the magnitude and direction of deviation from the patient's uncompromised O2 tension could lead to inappropriate management. We conclude that capillary blood specimens should not be used for pO2 determinations in newborns.

Blood Gas Analysis↗
PubMed1978

Non-specific serum iron in thalassaemia: an abnormal serum iron fraction of potential toxicity.

Iron binding in the sera of 35 patients with beta thalassaemia major and intermedia was studied. In patients receiving regular blood transfusions since infancy transferrin was completely saturated and about 2.7--7.1 mumol/l of the serum iron could be removed by dialysis or ultrafiltration in the presence of a chelating agent or by filtration on DEAE-Sephadex-catecholdisulphonic acid columns. In contrast, less than 1.0 mumol/l of transferrin bound iron was removed when subjected to the same procedures. The non-specific iron of thalassaemic sera could no longer be demonstrated after incubation with normal serum. These findings indicate that non-specific iron is a chelatable with normal serum. These findings indicate that non-specific iron is a chelatable compound which is readily available for transferrin binding. In view of the known toxicity of unbound iron, its identification in thalassaemic sera might be of relevance to the pathogenesis of tissue damage and the protective effect of iron chelating therapy in this disease.

Adolescent↗
PubMed1977

Hormone changes in relation to the time of fetal death after prostaglandin-induced abortion.

The changes in unconjugated estradiol-17beta and estriol, progesterone and chorionic somatomammotropin (HCS) in peripheral plasma have been studied in 18 women at 30-minute intervals following intra-uterine prostaglandin E2 administration for therapeutic termination of second trimester pregnancy. The hormonal changes were related to the time of fetal death detected by the disappearance of fetal heart pulsations. Prostaglandin E2 was given by the intra-amniotic route with urea (5 patients) or with intravenous oxytocin (5 patients), or by the extra-amniotic route with intravenous oxytocin (8 patients). Fetal death occurred rapidly with intra-amniotic PGE2, but usually at a late stage with extra-amniotic PGE2. Three fetuses in the extra-amniotic group died at or just before abortion. A variety of fetal heart changes were noted and the time of fetal death did not appear to influence the time of abortion within each treatment subgroup. Estradiol and estriol showed a sligh but persistent fall over 24 hours prior to induction of abortion. A more rapid fall usually occurred after induction, with a consistent fall around the time of fetal death. Progesterone and HCS usually fell much less before and immediately after fetal death. A marked rise in estradiol sometimes occurred before fetal death, particularly in the intraamniotic PGE2 and urea subgroup. Estriol levels declined more rapidly before than after fetal death, whereas fetal death had less consistent effects on the other hormones. All hormones had usually fallen considerably at the time of abortion, and in some individuals marked fluctuations in hormone levels were seen.

Abortion, Induced↗
PubMed1976

Single-dose evaluation of a new enteric-coated aspirin preparation.

The bioavailability of a new enteric-coated tablet of aspirin (Ecotrin, Smith, Kline and French) was evaluated after single doses to eight volunteers. One tablet was administered to each subject on four occasions--twice after a light breakfast, once after a heavy breakfast and once after pretreatment with metoclopramide. The study utilized non-invasive techniques. The rate of absorption of aspirin was estimated by the time course of concentrations of salicylate in saliva, while the total bioavailability was determined by the recovery of total salicylate in urine. The urinary recovery of aspirin from all 32 trials was 575 +/- 25 mg (mean +/- standard error), representing 89% +/- 4% of the administered dose. The different treatments did not significantly alter the urinary recovery. The absorption of aspirin from the enteric-coated tablets was delayed and slow. Absorption was retarded by a heavy meal and hastened by pretreatment with metoclopramide. The effect of metoclopramide is consistent with the release of aspirin in the small intestine. Overall, the single-dose tests indicated satisfactory functioning of the enteric coating.

Adult↗
PubMed1975

The effect of serum and experimental variables on the transferrin and reticulocyte interaction.

The transfer of iron from transferrin to the developing erythrocyte is a research area of high interest and considerable controversy. We have found that the results of transferrin-reticulocyte incubation studies are quite sensitive to the experimental procedures that are utilized. Reticulocytosis has been induced in rabbits by phelbotomy and phenylhydrazine injections. While the latter gives a higher reticulocyte count, the cells appear to exhibit an altered transferrin-membrane interaction. Transferrin has been iodinated by published methods utilizing chloramine-T and molecular iodine. The iodotransferrin products exhibit the same iron donation ability, however, evidence was found that the chloramine-T treatment leads to a nonspecific binding of transferrin to the reticulocyte. The means of saturating transferrin with 59Fe is also of prime importance. Fe(NH4)2(SO4)2 and especially FeCl3 were found to yield nonspecifically bound iron when added to transferrin or serum. This artifact was reflected in an altered transferrin-reticulocyte interaction. Using what we believe to be optimal conditions, the effect of serum on the transferrin-reticulocyte system was re-examined. The results clearly indicated an enhancement of iron uptake by reticulocytes in the presence of serum, as well as an accelerated incorporation of iron by the cytoplasmic fraction.

Animals↗
PubMed1975

[Effect of cyclophosphamide on themetabolism of erythrocytes].

Cyclophosphamide was applied i.p. in the dose of 100 mg kg-1 to rats. After one, two, three, and seven days the animals were killed and in the collected heparinized blood the incorporation of o-phosphate 32P in erythrocytes was determined in vitro at 37 degrees C and in 35 minutes. Decreased incorporation in animals with Cyclophosphamide indicated, compared with the control, disturbed metabolism of phosphate. The method can be applied as a criterion of secondary toxic effects in the treatment of cancerostatics of alkylation type.

Animals↗