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Biomedical subjects

E Baker

Publications and source records attributed to E Baker.

At least 271 records · Page 15Linked to original sources
PubMed1983

The effects of scheduling format and booster sessions on a broad-spectrum psychosocial approach to smoking prevention.

The effectiveness of a fifteen session psychosocial smoking prevention strategy was tested on 902 seventh graders from seven junior high schools in suburban New York over 2 years. The prevention program was implemented by regular classroom teachers and consisted of a cognitive component dealing with the immediate consequences of cigarette smoking, a decision-making component, a relaxation-training component, a social skills training component, and a self-improvement component. In addition to testing the overall effectiveness of this approach, the relative efficacy of two different scheduling formats was compared and the extent to which "booster" sessions conducted during the year after completion of the program helped to maintain reductions in new smoking was also examined. Results indicated that the prevention program was able to reduce new cigarette smoking by 50% at the end of the first year and by 55% at the end of the second year for the intensive format condition. New regular cigarette smoking was reduced by 87% in the second year for the students in the booster condition. Significant changes consistent with nonsmoking were also evident on several cognitive, attitudinal, and personality variables.

Adolescent↗
PubMed1983

Distribution of transferrin and transferrin receptors in the rabbit placenta.

The quantity and distribution of transferrin and transferrin-binding sites in the placenta were investigated in rabbits on the 28th-29th days of pregnancy. The animals were injected intravenously with a mixture of 59Fe-125I-labelled rabbit diferric transferrin and 131I-labelled rabbit albumin. The binding of transferrin to placentas removed 3-75 min later was determined by using the 131I-labelled albumin values to correct for tissue content of plasma. Mean values for transferrin binding of 1460 and 560 micrograms/g tissue were obtained 3-15 and 45-75 min after injection, respectively. Gel filtration of placental extracts prepared with the non-ionic detergent, Teric 12A9, showed that the 125I-labelled transferrin bound to a large molecular weight component which had the properties of a specific receptor. The receptor had a higher affinity for diferric transferrin than for apotransferrin. The subcellular distribution of transferrin binding sites was determined by differential centrifugation of placental homogenates and by electron microscope autoradiography. The results with the former method indicated that the transferrin was bound to the microsomal fraction of the cells. Autoradiography showed that the majority of the transferrin molecules were at intracellular sites, mainly on the membrane of intracellular vesicles. It is concluded that iron-containing transferrin molecules enter the trophoblast cells by endocytosis or via a canalicular system after binding to cell membrane receptors. The higher affinity of the receptors for diferric transferrin than for apotransferrin explains the difference in amount of transferrin binding found within 15 min of injecting labelled diferric transferrin and that found 45-75 min later when much of the iron had been removed from the transferrin.

Animals↗
PubMed1983

Transcatheter occlusion of a Blalock-Taussig shunt with a detachable balloon in a child.

A case of transcatheter occlusion of a Blalock-Taussig shunt with a detachable silicone filled balloon is described. This 11 year old boy had previously had a repair of tetralogy of Fallot together with ligation of a large Blalock-Taussig shunt. Though there was a good surgical result, the shunt proved to be incompletely closed leaving a significant left to right shunt. As an alternative to a further operation a silicone filled balloon was detached in the Blalock-Taussig shunt and this successfully closed the fistula.

Angioplasty, Balloon↗
PubMed1982

Genetic length of a human chromosomal segment measured by recombination between two fragile sites.

Two families were studied in which the same homolog of chromosome pair 10 expressed both the fragile sites on the long (q) arm at 10q23 and 10q25. Recombination between the fragile sites was observed in 3 of the 27 offspring in whom it could occur. The genetic length of chromosome between the fragile sites was 11 female centimorgans within a 95 percent probability interval of 4 to 28 centimorgans. This estimate of genetic length is comparable to those obtained with other methods.

Chromosome Banding↗
PubMed1982

Sister-chromatid exchange (SCE) analysis in mothers exposed to DNA-damaging agents and their newborn infants.

The incidence of SCE in the lymphocytes of mothers and their newborn infants was determined. A detailed antenatal history of parental habits such as smoking, alcohol consumption and possible exposure to DNA-damaging agents was documented. The results showed that the SCE rate in the newborn is significantly less than that of their mothers. Mothers who consumed alcohol, but not cigarette smokers, had a significantly increased SCE rate compared to control mothers. However, these maternal habits did not affect the SCE rate of their infants. Neonates with neural tube defects showed a significantly increased SCE rate compared to normal babies.

Abnormalities, Multiple↗
PubMed1982

Effect of iron saturation on transferrin uptake by reticulocytes. A morphological study.

The presence of iron on the transferrin molecule increases its affinity for and sojourn time on the reticulocyte. This could be due to selective internalization of iron-containing transferrin molecules. This possibility was investigated by electron microscopic autoradiography. Rabbit reticulocytes were incubated with rabbit transferrin at 6, 33, and 72% iron saturations, and the distribution of transferrin molecules at membrane and intracellular locations was assessed by grain counting. The results showed that (1) both apotransferrin and iron transferrin enter the cell interior and (2) the amount of intracellular transferrin was primarily controlled by the concentration of membrane-bound transferrin and not by its iron saturation.

Animals↗
PubMed1981

Sister chromatid exchange in aplastic anemia.

The incidence of sister chromatid exchanges (SCE) in the lymphocytes of patients with aplastic anemia (AA) was determined before and after exposure to mitomycin C (MMC). The "baseline" SCE rate was significantly higher in AA, but MMC-induced SCE rate was not different compared to controls. It is suggested that some patients with AA may have an underlying DNA damage.

Adolescent↗
PubMed1981

Iron release from isolated hepatocytes.

The isolated hepatocyte suspension was evaluated as an experimental procedure for investigating liver iron metabolism. Following prelabelling in vivo with transferrin-59Fe, isolated hepatocytes released radioactive iron in vitro by a temperature dependent process, without change in cell viability. Iron mobilization was increased by serum, apotransferrin and a range of iron chelators, of which the most effective were citrate, desferrioxamine and the ionophore A 23187. The rate of iron release was inversely related to oxygen levels, indicating that a ferric-ferrous reduction was involved in iron mobilization. The uncoupler TTFB, DTPA, and hypercapnia caused a reduction in iron release, but the metabolites cysteine, NADH and ascorbic acid had no effect. It was concluded that isolated hepatocytes are a useful experimental model for studying iron metabolism and for further evaluation of iron chelators.

Animals↗
PubMed1980

Effect of thirty-two per cent dextran 70 on peritoneal adhesion formation and re-formation after lysis.

Thirty-two per cent dextran 70 in dextrose (Hyskon) has been reported effective in limiting adhesion formation following a peritoneal injury when employed in doses larger than that known to be safe for intraperitoneal use in humans. The effectiveness of a lower dosage believed to be safe for human use was investigated. Female rabbits received a standardized injury to their uterine horns and proximal fallopian tubes. Following the injury, Hyskon (2.5 ml/kg of body weight) was dripped over the sites of injury in the treatment group. Animals were reoperated upon 2 weeks later, and adhesions were scored. Hyskon significantly reduced adhesion formation. In a second experiment the effect of Hyskon on adhesion re-formation was evaluated. Adhesions were induced in the same manner. Two weeks later, the animals were reoperated upon, and adhesions were scored and lysed. Hyskon was instilled in the treatment group as in the first experiment. No significant difference was noted between adhesion scores in control and treatment groups after adhesion induction or when re-evaluated 2 weeks after lysis.

Animals↗
PubMed1980

The regulation of iron release from the perfused rat liver.

Factors affecting iron efflux from the isolated perfused rat liver were studied following the intravenous administration of transferrin-(59)Fe or transferrin-(55)Fe administered to the rat from 1.5 h to 3.5 d before perfusion of the liver. The liver was perfused with rat red cells suspended either in rat plasma or Eagle's Basal Medium (EBM). The mean rate of efflux into a plasma pool containing normal iron and transferrin concentrations was 0.9% of the initial hepatic radioactive iron pool per hour. In EBM the average rate of efflux was 0.1%/h and this could be increased to the rate observed with plasma by the addition of apotransferrin. The rate of iron release from the liver in the presence of apotransferrin or other chelators was inversely proportional to the time of prelabelling. Maximal release rates were observed in livers perfused within 5 h of administering transferrin-(59)Fe to the rat. The effect of apotransferrin on efflux into EBM was concentration dependent. However, the maximum release of liver iron by apotransferrin occurred at physiological apotransferrin concentrations and addition of apotransferrin to plasma produced no increase in the rate of iron efflux. The stimulation of iron release in EBM caused by apotransferrin could be reversed by reducing the unsaturated iron binding capacity of the perfusate, either by addition of iron or removal of apotransferrin. However, increasing the iron concentration in the perfusate by the addition of iron-saturated transferrin without any reduction in the unsaturated iron binding capacity additionally increased iron release into plasma and EBM. This presumably reflects the exchange of plasma transferrin-(56)Fe for liver (59)Fe. Hence iron release measured in these studies represent the sum of two processes-net release of (59)Fe induced by apotransferrin and iron exchange between plasma and liver iron pools. Apotransferrin and desferrioxamine were equally effective, per unit iron binding capacity, in mobilizing liver iron, and may compete for the same parenchymal iron pool. This suggests that mobilization of iron by apotransferrin may depend solely on its ability to chelate ferric iron and not on a more specific ferroxidase activity or interaction with membrane receptors.

Animals↗
PubMed1979

Liposome entrapped desferrioxamine and iron transporting ionophores: a new approach to iron chelation therapy.

Liposome-entrapped desferrioxamine was administered to iron-over-loaded 59Fe lavelled mice. When given orally or intraperitoneally entrapment did not enhance the effect of the chelator, but given intravenously liposomal desferrioxamine doubled the 59Fe excretion for a given dose of the drug, and excretion after a single dose continued for up to 3 d. In addition, liposomes containing ionophore A23187 administered concurrently with DTPA caused an excretion of 59Fe, whereas DTPA alone had no effect.

Animals↗