Biomedical subjects

B C Eichhorst

Publications and source records attributed to B C Eichhorst.

4 recordsLinked to original sources

PubMed1988

Contraception.

The technology of fertility control has made dramatic strides in the past 25 years, offering a wider variety of safe, effective contraceptive choices than ever before. Lower dose oral contraceptives, new barrier techniques, and improved IUDs have been important recent advances, and new methods of hormonal delivery offer promise for the future. However, the search for safer, more effective, and more convenient contraceptive options must continue as a high research priority.

Contraception↗

PubMed1977

Factors determining human chorion laeve permeability in vitro.

An increased mean diffusion permeability across human chorion laeve in vitro was measured for meperidine (D = 5.26 x 10(-6) cm.2 sec.-1) and diazepam (D = 4.51 X 10(-6) cm.2 sec.-1). These values corresponded to large chloroform-buffer partition coefficients (49 and 29) measured for these two compounds. Diffusion permeability values of 3.98 and 2.18 x 10-6 cm.2 sec.-1 measured for urea and glucose corresponded to their relative insolubility in lipid, as indicated by chloroform-buffer partition coefficients of 0.05 and 0.0004, respectively. An increase in placental permeability in vitro to the weak organic acid 5,5-dimethyl, 2,4-oxazalidinedione at lower pH's corresponded to an increase in the fat-soluble nonionized fraction of this compound. These data support the concept that this tissue is most permeable to compounds of relatively small molecular size and/or with a high level of lipid solubility. The large diffusion permeability values measured for meperidine and diazepam suggest that these compounds will diffuse rapidly between mother and fetus at a maximal rate limited only by uterine blood flow.

Cell Membrane Permeability↗

PubMed1976

Permeability of chorion laeve to succinylcholine in vitro.

The simultaneous diffusion of 14C-succinylcholine and p-amino hippurate across human placental tissue in vitro was measured. Column chromatographic purification of the radioactivity followed by paper chromatographic analysis showed little alteration of the succinylcholine during the course of these experiments. Similar chloroform-buffer partition coefficients for the two solutes were measured. Thus in these experiments, the nearly identical transfer rates of these two similar sized, lipid-insoluble compounds indicated that succinylcholine crosses human placental tissue in quantitites compatible with its molecular size and lipophobic nature, and that the diffusion rate is not significantly influenced by its increased molecular charge.

Aminohippuric Acids↗

PubMed1976

Permeability of human chorion laeve to diazepam and meperidine.

In vitro placental permeability to diazepam (Valium) and meperidine (Demerol) in excess of that measured for antipyrine, suggest that these compounds will diffuse across placental tissue in vivo at a maximal or perfusion-limited rate. Such findings correspond to the high fetal blood levels reported for these substances following maternal administration and indicate that these lipid-soluble analgesics cross this tissue by transcellular as well as extracellular pathways.

Aminohippuric Acids↗