PubMed Health⌕ Search

Biomedical subjects

B Duncan

Publications and source records attributed to B Duncan.

At least 19 recordsLinked to original sources
PubMed1992

Human fetal liver-derived CD7+CD2lowCD3-CD56- clones that express CD3 gamma, delta, and epsilon and proliferate in response to interleukin-2 (IL-2), IL-3, IL-4, or IL-7: implications for the relationship between T and natural killer cells.

Cells from fetal liver or fetal and adult bone marrow that are membrane (m)CD3 negative and have not rearranged TCR genes but express CD3 proteins in their cytoplasm are considered to be committed T-cell progenitors. Recent findings question whether CD3 is T-cell specific because fetal natural killer (NK) cells have been shown to express cCD3 delta and epsilon proteins. To further examine the relationship between T and NK cells, we generated mCD3-cCD3+ clones from fetal liver. Two stable clones, FL412 and FL508, isolated from different donors, were selected on the basis of absence of the NK cell marker CD56. These clones shared a common phenotype of CD7+CD2lowCD3-CD4-CD8-CD5-CD6-CD11b+CD16-CD56 -. Like fetal NK clones, these clones expressed cytoplasmic CD3 delta and epsilon transcripts and proteins. However, the clones exhibited no or very low levels of cytotoxic activity against K562, JY, or Daudi, which were lysed efficiently by fetal NK clones. TCR beta, gamma, and delta genes in these clones were in germline configuration. Furthermore, both FL412 and FL508 responded not only to interleukin-2 (IL-2), IL-4, or IL-7, but also to IL-3 with proliferation. These results suggest that FL412 and FL508 retained some characteristics of a putative T or NK precursor in the fetal liver and may be useful for analyses of this poorly defined cell type.

Antigens, CD↗
PubMed1992

Maternal mortality in the Thyolo District of southern Malawi.

The Sisterhood Method, a community-based survey technique, was used to estimate the Life Time Risk of a woman dying a maternal death in Southern Malawi. With this figure, the maternal mortality ratio for that area was calculated to be 409 deaths per 100,000 live births. The 4124 adults interviewed reported 150 maternal deaths in sisters. An in-depth questionnaire was then used to determine that 56% of these deaths occurred outside a health facility, largely due to lack of transportation or poor access to fixed health care facilities; 25% died from excessive hemorrhage; 20% from obstructed labour; 18% from abortion; 13% from sepsis; while eclampsia accounted for only 4% of the maternal deaths. This field experience with the Sisterhood Method technique combined with an in-depth questionnaire for determining causes of maternal deaths has provided useful information in a simple and cost-effective manner for use in planning intervention strategies designed to decrease maternal mortality.

Adolescent↗
PubMed1992

Treatment of infants with acute diarrhea: what's recommended and what's practiced.

In 1985, the American Academy of Pediatrics (AAP) published a policy statement on the treatment of infants with acute diarrhea complicated by mild to moderate dehydration. To determine how closely physicians in the United States follow the AAP's treatment guidelines, a questionnaire was sent to 457 pediatricians and 360 family practitioners. The questionnaire presented a hypothetical infant with acute diarrhea complicated by mild to moderate dehydration and included questions regarding the number of such patients seen yearly, length of time used to rehydrate the infant, and how formula or solids are introduced following rehydration. Complete responses were received from 53% of pediatricians and 40% of family practitioners. The number of patients with acute diarrhea seen per year did not affect physician's treatment. Pediatricians and family practitioners responded similarly to most questions. Contrary to the AAP's guidelines to rehydrate in 4 to 6 hours, 62% of responding physicians extend the rehydration period to 12 to 24 hours. Also contrary to the AAP's recommendations, 62% of pediatricians and family practitioners use a lactose-free formula. The majority of responding physicians do follow the AAP's treatment guidelines to initiate feedings with diluted formula. Significantly more pediatricians than family practitioners advance to a full-strength formula within 1 day (P = .011). Fewer than 50% of physicians polled started solids within 24 hours as suggested by the AAP. Overall, the findings suggest that very few pediatricians and family practitioners follow all aspects of the AAP's treatment guidelines for infants with acute diarrhea complicated by mild to moderate dehydration.

Acute Disease↗
PubMed1991

The neonatal immune response to washed and irradiated red cells: lack of evidence of lymphocyte activation.

A total of 21 neonatal infants (11 males and 10 females) were evaluated for lymphocyte subpopulation changes and cellular activation following the receipt of washed and gamma-irradiated red cells. The mean donor exposure was 2 +/- 1.5 donors, and the mean white cell concentration of each 10-mL-per-kg transfusion was 2 x 10(7) cells. A total of 2800 rad (28 Gy) was delivered to each red cell unit prior to washing. The lymphocyte subsets CD3+, CD4+, CD8+, CD19+, CD3+/CD25+, CD3+/HLA-DR, CD4+/CD45RA, CD4+/CDw29, and CD4+/ICHL-1 were analyzed, as were plasma gamma-interferon and neopterin levels, before and after blood transfusion. Posttransfusion samples were obtained from 3 to 12 days after the last blood transfusion. There were no posttransfusion changes in the percentage of lymphocyte subsets analyzed. Furthermore, overlay-histogram analysis of pretransfusion and posttransfusion CD45RA-, CDw29-, and UCHL-1-positive helper T cells failed to reveal a shift in mean channel fluorescence intensity, which is indicative of a lack of cellular activation. Gamma-interferon levels remained unchanged after transfusion (range, 90 +/- 5.9 to 95.5 +/- 5.3 pg/mL), as did neopterin levels (range, 3.7 +/- 1.5 to 4.6 +/- 1.5 ng/mL). This study could not find any evidence, by either cellular or humoral markers, of the activation of neonatal lymphocytes by transfusion. It is hypothesized that this failure to observe lymphocyte activation is due to the low number of donor white cells present in washed, irradiated red cells and/or to a lack of recipient recognition of transfused, allogeneic, donor white cells.

Blood Transfusion↗
PubMed1991

The influence of preschool pertussis immunization on an epidemic of pertussis.

Between 1988 and 1989 there were 896 reported cases of pertussis in Arizona. Of the 781 investigated cases 55 were identified in children younger than 5 years of age. Thirty-five percent of children between 6 months and 5 years of age were not fully immunized; 3 infants died. Approximately 50% of infected children between 5 and 14 years of age had not received 5 doses of pertussis vaccine. Of the 413 physician respondents to a questionnaire, fully 10% do not administer pertussis vaccine to preschool children because of parental, personal or other reasons. We hypothesize that the reservoir of pertussis-susceptible older children and young adults is augmented by this omission of the fifth diphtheria-tetanus toxoids-pertussis vaccine. Newer educational and vaccine strategies are necessary to prevent epidemics of pertussis.

Adolescent↗
PubMed1990

Complete heart block in fetal lambs. I. Technique and acute physiological response.

Prenatally diagnosed complete heart block (CHB), without associated cardiac anomalies, is often refractory to attempts to increase heart rate and cardiac output by medical therapy, and results in fetal death. We developed a model of CHB in fetal lambs in order to evaluate the acute physiological consequences of CHB and to assess the feasibility of fetal cardiac ventricular (V) and atrioventricular (AV) pacing. After hysterotomy and fetal sternotomy AV-sequential pacing leads were placed on the right atrium and ventricle (RV). Electromagnetic flow transducers were placed around the pulmonary artery and the ascending aorta to measure combined ventricular output (CVO) in normal sinus rhythm (NSR), CHB, AV, and V pacing. CHB block was successfully induced in 19 of 21 (90%) fetal lambs at 100 to 110 days' gestation by injection of formalin into the interventricular septum. Two fetuses were refractory to CHB despite multiple injections. The mean ventricular escape rate was 52 +/- 3 (+/- SEM) beats/min (range, 45 to 60 beats/min). CHB lasted for the period of study (1 to 8 hours), and spontaneously reverted to NSR in one fetus after 3 hours. Combined ventricular output in NSR was 470 +/- 31 mL/min (+/- SEM), which fell to 213 +/- 13 mL/min in CHB, 45% of normal CVO (P less than .0001). CVO during AV-sequential and V pacing was 77% (P = .02) and 62% (P less than .001), respectively, of combined ventricular output in NSR. Both RV (27%) and left ventricles (LV) (37%) showed compensatory increase in stroke volume during CHB.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Obesity and mortality in the Lipid Research Clinics Program Follow-up Study.

Using data from the Lipid Research Clinics Program for 1972-1983, the study presented here examined weight history and two indices of obesity: the body mass index (BMI) and the triceps skinfold (TSF) thickness. Cox regression analyses with and without adjustment for cardiovascular disease risk factors revealed a significant (p less than 0.05) quadratic association between BMI and all-causes mortality among men, but not women, after an average 8.4 years of follow-up; mortality was relatively high at both extremes of the BMI distribution. The association was stronger among smokers compared with nonsmokers, and it was apparent among male normotensives, but not hypertensives. All TSF-mortality associations and BMI associations with cancer and coronary heart disease mortality were weak and nonsignificant. Among men, per cent weight change in adulthood showed a significant inverse association with all-causes and cancer mortality. Because BMI and weight history were significantly associated with mortality after adjustment for other risk factors, they appear to be independent predictors of mortality among men.

Adult↗
PubMed1987

Dipyridamole: pharmacokinetics and effects on aspects of platelet function in man.

1. The effect of dipyridamole on platelet function was measured in twelve normal subjects given 150 or 200 mg tablets as single and multiple doses, and in six subjects given single doses of 25, 50 and 100 mg and multiple doses of 50 mg 8 hourly. 2. Platelet aggregation was measured in response to ADP and collagen. In the subjects given 150/200 mg, the platelets were assayed for content of cyclic AMP and for formation of thromboxane after addition of collagen. The responses to ADP and collagen and the cyclic AMP content were assessed in both the presence and absence of added PGE1. The pharmacokinetics of dipyridamole were studied in all subjects. 3. One hour after 150/200 mg single doses of dipyridamole there was significant inhibition of platelet aggregation in response to both collagen and ADP. There was no detectable effect on aggregation at other time points or with lower doses of dipyridamole. The addition of PGE1 to platelets prior to testing did not enhance the effect of dipyridamole on platelet aggregation. 4. In multiple doses, dipyridamole (150/200 mg twice daily for 11 days) had no detectable effect on platelet aggregation. 5. Dipyridamole did not have any effect on platelet cyclic AMP content, whether or not PGE1 was added prior to assay. 6. Dipyridamole did not affect platelet thromboxane formation. 7. Plasma dipyridamole concentrations were maximal 1-2 h after ingestion, at the same time that inhibition of platelet aggregation was detected. The concentrations declined in a biexponential fashion, with a terminal half life of 24.1 +/- 1.9 h (mean +/- s.e. mean). In six of the 17 subjects, the mean steady state plasma concentration was less than 75% of the value predicted from the single dose data.

Adolescent↗
PubMed1979

A comparison of growth: Spanish-surnamed with non-Spanish-surnamed children.

Weight, height, and head circumference measurements of 4,167 Spanish-surnamed school-aged children were compared with similar data from 2,322 non-Spanish surnamed children who resided in the same Denver, Colorado neighborhoods. These data were also compared with data from six other studies. Both male and female Spanish-surnamed children were found to weigh less, be shorter, and have smaller head circumferences than non-Spanish-surnamed children living in the same Denver neighborhoods. The sizes of the children in these two populations residing in lower and lower-middle class neighborhoods were closer to each other than to the sizes of children from middle and upper-middle socioeconomic classes as measured in previous studies or to the sizes of children in the recently published cross-sectional National Center for Health Statistics study. Such comparisons suggest that growth retardation is more a reflection of socioeconomic factors than of ethnic-genetic factors.

Adolescent↗
PubMed1979

Change in worker/nonworker ratios for women.

Effects of age, birth year, and observation year on work behavior are estimated by minimum logit chi-square regression, using data from Current Population Surveys. Most of the observation-year effect is captured by indicators of the business cycle. Further, a model which permits the cycle effects to vary by age is preferred over any additive model. The ratio for young women is most depressed relative to that for older women when times are "good".

Age Factors↗
PubMed1976

Iron and blood donation. Evaluation of a kit method for routine use in a blood transfusion service.

Manifest iron-deficiency anaemia is preceded by a latent stage in which normal haemoglobin levels coexist with low serum iron levels. Regular blood donation involves the removal of significant amounts of iron, and in susceptible donors, may aggravate iron deficiency. It is important for a blood transfusion service to be able to identify these susceptible donors. A commercial kit for the determination of serum iron levels was evaluated and found suitable for introduction as a routine screening test for a transfusion service. A survey of serum iron levels of 200 blood donors showed that 12 1/2% had levels below the normal reference range.

Anemia, Hypochromic↗