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Biomedical subjects

P Elder

Publications and source records attributed to P Elder.

11 recordsLinked to original sources
PubMed2004

Therapy-related myelodysplasia and leukemia occur infrequently following VP-16 priming and autotransplantation without total body irradiation.

The use of VP-16 for stem cell mobilization has been cited as a significant risk factor for the development of therapy-related myelodysplasia/leukemia (tMDS/tAML) following autologous transplantation. The present study analyzed a large cohort of patients who underwent autotransplantation following stem cell mobilization with VP-16 and radiation-free preparation in order to determine the risk of tMDS/tAML. The estimated incidence of 9.9% at 7 years suggests that in the absence of TBI, VP-16 priming is not associated with an increased incidence of tMDS/tAML.

Adolescent↗
PubMed1995

Empirical development of brief smoking prevention videotapes which target African-American adolescents.

Two studies are described which provide evaluations for two brief videotapes developed as supplemental materials in the prevention of tobacco use among African-American adolescents. One videotape (the "soap opera") provides a more general audience-oriented presentation of prevention material and it was filmed primarily at a shopping mall, whereas the other videotape (the "rap") provides a "hip-hop generation" presentation, and it was filmed primarily at an outdoor hangout. The first study compared the two videotapes against each other. The second study compared the two videotapes combined in the same presentation, controlling for order of presentation, against a discussion group control. The results of the two studies indicated few differences in receptivity to the two videotapes among primarily African-American and Latino young adolescents. The rap videotape was rated as more accurate in its depiction of the African-American lifestyle, although both videotapes were equally liked. When shown together, the videotapes were not found to be superior in decreasing behavioral intention to smoke compared to a discussion group control. No change in trial of smoking was observed within or across conditions measured over a pre-post summer interval. These data suggest that "culturally sensitive" videotapes have no more of a short-term effect on youth than do other types of brief interventions which involve minority implementers.

Adolescent↗
PubMed1993

Blood flow measurement by Doppler ultrasound: a question of angles.

Ultrasound Doppler equipment is widely used to estimate blood velocity and volume flow. Recently there has been correspondence concerning the origin of the Doppler shift in blood vessels. The assumption that only the movement of the target need be considered is challenged by the observation that Doppler shifts occur where there is relative motion. In blood there is unlikely to be relative motion between a reflecting blood corpuscle and its supporting plasma. In the simple case of plug flow the relative movement takes place at the vessel wall. An investigation is described which uses a flow rig Doppler phantom to assess what effect, if any, this phenomenon would have on Doppler shift results obtained by insonating a vessel such as the aortic arch and range gating through a curved section where flow velocity gradients are encountered. It has been assumed that if the sample volume were to lie in that part of the vessel in which the blood velocity vector were directly towards the probe, then an angle of 0 degrees could be assumed for calculations using the Doppler equation. Our results indicate that the observed Doppler shifts lie midway between those expected if the shift were to occur solely at the first moving fluid boundary and those originating only from scatterers within the sample volume.

Blood Circulation↗
PubMed1992

Kinetic characterization of reductant dependent processes of iron mobilization from endocytic vesicles.

The reductant dependence of iron mobilization from isolated rabbit reticulocyte endosomes containing diferric transferrin is reported. The kinetic effects of acidification by a H(+)-ATPase are eliminated by incubating the endosomes at pH 6.0 in the presence of 15 microM FCCP to acidify the intravesicular milieu and to dissociate 59Fe(III) from transferrin. In the absence of reductants, iron is not released from the vesicles, and iron leakage is negligible. The second-order dependence of rate constants and amounts of 59Fe mobilized from endosomes using ascorbate, ferrocyanide, or NADH are consistent with reversible mechanisms. The estimated apparent first-order rate constant for mobilization by ascorbate is (2.7 +/- 0.4) x 10(-3) s-1 in contrast to (3.2 +/- 0.1) x 10(-4) s-1 for NADH and (3.5 +/- 0.6) x 10(-4) s-1 for ferrocyanide. These results support models where multiple reactions are involved in complex processes leading to iron transfer and membrane translocation. A type II NADH dehydrogenase (diaphorase) is present on the endosome outer membrane. The kinetics of extravesicular ferricyanide reduction indicate a bimolecular-bimolecular steady-state mechanism with substrate inhibition. Ferricyanide inhibition of 59Fe mobilization is not detected. Significant differences between mobilization and ferricyanide reduction kinetics indicate that the diaphorase is not involved in 59Fe(III) reduction. Sequential additions of NADH followed by ascorbate or vice versa indicate a minimum of two sites of 59Fe(III) residence; one site available to reducing equivalents from ascorbate and a different site available to NADH. Sequential additions using ferrocyanide and the other reductants suggest interactions among sites available for reduction. Inhibition of ascorbate-mediated mobilization by DCCD and enhancement of ferrocyanide and NADH-mediated mobilization suggest a role for a moiety with characteristics of a proton pore similar to that of the H(+)-ATPase. These data provide significant constraints on models of iron reduction, translocation, and mobilization by endocytic vesicles.

Animals↗
PubMed1990

Non-operative management of malignant intestinal obstruction.

Intestinal obstruction is a relatively common clinical problem in patients with advanced cancer, particularly those with colorectal and ovarian tumours. A proportion of patients have a non-malignant cause for their obstruction, but in the remaining patients obstruction will be caused by advanced malignancy itself. In the past, most patients were either managed surgically or by nasogastric intestinal decompression and intravenous hydration. Surgery in patients with advanced cancer is associated with high mortality and morbidity. Effective surgical decompression is difficult. We have managed 24 patients with advanced abdominal malignancy and previous operative or radiological evidence of intestinal obstruction without operation. The technique is only appropriate for patients in whom a solitary or correctable obstructing lesion can be excluded. The patient is encouraged to take free fluid and a diet low in fibre. Intestinal colic is managed with morphine, the dose required being titrated for each individual patient against background pain and colic. Vomiting is controlled by the parenteral administration of antiemetic drugs. To simplify drug administration, morphine and metoclopramide are mixed in the same syringe and infused subcutaneously simultaneously. In our 24 patients the mean survival rate after the onset of complete obstruction was 29.2 days. The mean dose of morphine infused was 9.2 mg/h, and the mean dose of metoclopramide was 6.9 mg/h. The case of an 82-year-old male patient is presented. We commend the technique to surgeons contemplating surgery in these very difficult patients. It is simple, relatively non-invasive and saves the patients the pain, discomfort and complications of unproductive surgery.

Adult↗
PubMedDate not supplied

Qualitative development of smoking prevention programming for minority youth.

Brief discussion groups were completed with 211 predominantly African American and Latino seventh graders to investigate reasons for adolescent smoking and perceived efficacious smoking prevention program strategies. Study data consisted of audiotaped group discussions, which were content-coded, and open-ended posttest responses. The results indicated that, through use of relatively nondirected methods, reasons for smoking and smoking prevention methods generated by African American and Latino youth were similar to those popularly endorsed by white youths in previous research. Perhaps, optimal program contents are similar across ethnic groups. Still, one may speculate that identification with and diffusion of prevention messages may be maximized if they demonstrate cultural relevancy.

Adolescent↗
PubMedDate not supplied

The relation of ethnic identification with cigarette smoking among US urban African American and Latino youth: a pilot study.

Primarily African American and Latino seventh graders (N = 545) attending health and science classes at three urban Southern California junior high schools were administered a 13-item ethnic identification assessment during one class period, to investigate the relationship between ethnic identification and tobacco use. For African Americans, the perception of looking different from other ethnic groups was found to be associated with avoidance of peer tobacco use. Among Latinos, the perception of being liked by other ethnic groups, and enjoying interaction with people outside of their ethnic group, were found to be associated with negating peer influence for tobacco use. Watching television shows with main characters of same ethnic group was associated with being able to make friends without using tobacco, for both ethnic groups. For Latinos, ever trying a cigarette was associated with the perception of being liked by other ethnic groups. These results suggest there may be elements inherent in ethnic identification protective against peer influence for smoking among ethnic minority youth. Also, acculturation of Latinos to the majority population may increase their risk for experimentation with tobacco products.

Adolescent↗