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David Archer

Publications and source records attributed to David Archer.

7 recordsLinked to original sources
PubMed2005

Murine and math models for the level of stable mixed chimerism to cure beta-thalassemia by nonmyeloablative bone marrow transplantation.

Stable mixed chimeric stem cell transplantation in hemoglobinopathies exploits shorter erythroid survival in hemolytic anemias, providing normal donor red blood cells with a competitive survival advantage. This study examined the level of stable mixed chimerism necessary for complete hematological cure of the thalassemic phenotype, using a nonmyeloablative busulfan chemotherapeutic preparation. Thalassemic mice transplanted from congenic wild-type donors developed partial mixed chimerism. Hematologic cure required >80% donor red blood cells and only >13% donor white blood cells. Murine and human transplant results were compared with a math model for survival advantage of donor peripheral blood cells produced by steady-state chimeric marrow.

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PubMed2002

Glacial--interglacial stability of ocean pH inferred from foraminifer dissolution rates.

The pH of the ocean is controlled by the chemistry of calcium carbonate. This system in turn plays a large role in regulating the CO2 concentration of the atmosphere on timescales of thousands of years and longer. Reconstructions of ocean pH and carbonate-ion concentration are therefore needed to understand the ocean's role in the global carbon cycle. During the Last Glacial Maximum (LGM), the pH of the whole ocean is thought to have been significantly more basic, as inferred from the isotopic composition of boron incorporated into calcium carbonate shells, which would partially explain the lower atmospheric CO2 concentration at that time. Here we reconstruct carbonate-ion concentration--and hence pH--of the glacial oceans, using the extent of calcium carbonate dissolution observed in foraminifer faunal assemblages as compiled in the extensive global CLIMAP data set. We observe decreased carbonate-ion concentrations in the glacial Atlantic Ocean, by roughly 20 micromolkg-1, while little change occurred in the Indian and Pacific oceans relative to today. In the Pacific Ocean, a small (5 micromolkg-1) increase occurred below 3,000m. This rearrangement of ocean pH may be due to changing ocean circulation from glacial to present times, but overall we see no evidence for a shift in the whole-ocean pH as previously inferred from boron isotopes.

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PubMedDate not supplied

Postmenopausal uterine bleeding profiles with two forms of continuous combined hormone replacement therapy.

OBJECTIVE: This study was designed to compare the bleeding profiles of conjugated equine estrogens 0.625 mg in combination with 2.5 mg medroxyprogesterone acetate (Prempro; CEE/MPA group), the most widely prescribed continuous combined hormone replacement therapy (CCHRT) in the United States, with 17beta-estradiol 1 mg combined with 0.5 mg norethindrone acetate (Activella; E(2)/NETA group), a newly available CCHRT preparation, over a 6-month period. DESIGN: This study was a prospective, randomized, multicenter, double-blind, controlled trial. A total of 438 healthy postmenopausal women were randomized and received treatment (Activella n = 217, Prempro n = 221). Each woman recorded bleeding diaries daily. Total cholesterol, triglycerides, and endometrial biopsies were obtained at screening and end-of-trial visits. RESULTS: The more favorable bleeding profile was found in the E(2)/NETA (Activella) group. The differences in bleeding patterns were most marked in the first 3 months of treatment in women who were 1-2 years from last menses, with no bleeding in 71.4% vs. 40.0%; ( p = 0.005) and with no bleeding and no spotting in 54.8% vs. 17.1%; (p = 0.001). Triglycerides fell by 8.5% in the E(2)/NETA group and increased by 11.7% in the CEE/MPA group (p < 0.001). Total cholesterol declined by 9.1% and 6.9%, respectively. CONCLUSION: The most important factor in the continuation of HRT is uterine bleeding. E(2)/NETA has significantly less bleeding than the most commonly prescribed CCHRT CEE/MPA, therefore; E(2)/NETA should be associated with improved continuation rates. The patient taking E(2)/NETA will receive effective treatment for her menopausal symptoms with less bleeding.

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