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Biomedical subjects

M Jacobson

Publications and source records attributed to M Jacobson.

252 records · Page 14Linked to original sources
PubMedDate not supplied

Use of tannic acid to study cytoplasmic vesicles and membrane invaginations in epididymal fat pads of ageing mice.

A staining technique based upon the known ability of tannic acid to selectively stain the outer layer of the triple-layered plasma membrane was used, along with electron microscopic examination of stained, serial sections, to differentiate between surface invaginations, clusters of invaginations, free vesicles and tubular channels in epididymal fat pads from young, fed and fasted mice and from old, fed mice. A preliminary semiquantitative evaluation of the average number of each type of structure per cell was attempted. There were no significant numbers of free cytoplasmic vesicles of approximately 50 nm diameter (the dimension of most surface invaginations) under any conditions studied. Most apparent vesicles were stained by tannic acid and were, therefore, actually invaginations of the plasma membrane. There were no tubular channels of this size seen in any of the electron micrographs examined in serial sections. We estimated that there are about 50 single invaginations per micron2 of plasma membrane surface in both young and old fed mice. In addition there were about 20 invaginations/micron2 grouped as clusters of 2-15 per group (mean, 4 per group) in the fed mice. There was a tendency for the number of invaginations in clusters to increase during fasting; about 40% of the surface invaginations were grouped in clusters in adipocytes of fasted mice. Although there was no effect of ageing on the concentrations of surface invaginations or in their groupings as clusters, the total number of invaginations per cell must have increased almost 3-fold as the cells enlarged. The function of these surface invaginations and deeply penetrating groups of invaginations remains to be elucidated.

Adipose Tissue↗
PubMedDate not supplied

Is there a pharmacokinetic interaction between foscarnet and zalcitabine during concomitant administration?

Foscarnet, an antiviral agent used in the treatment of cytomegalovirus infection, and zalcitabine, an antiretroviral nucleoside analogue used in the treatment of human immunodeficiency virus infection, are commonly used concomitantly. Foscarnet and zalcitabine may interact pharmacokinetically, as both compounds are partially eliminated by renal tubular secretion. Owing to dose-related toxicities associated with these two drugs, it is essential that we have data regarding their pharmacokinetic disposition during concomitant therapy. Twelve patients randomly received either foscarnet (four doses) or zalcitabine (five doses) (Phase 1), followed by concomitant foscarnet (four doses) and zalcitabine (six doses) (Phase 2), followed by dosing with the drug not received in Phase 1 (Phase 3). Following the last dose in each phase of the study, serial plasma samples were collected over 8 hours for zalcitabine and over 12 hours for foscarnet to determine the pharmacokinetics of each drug using noncompartmental analysis. Foscarnet plasma and urine levels were determined using high-performance liquid chromatography, and zalcitabine levels were determined using radioimmunoassay. No clinically significant alterations in the pharmacokinetics of foscarnet or zalcitabine occurred in this study. Thus despite the potential for foscarnet and zalcitabine to compete for renal tubular secretion, no apparent pharmacokinetic interaction exists between these two drugs at the clinically relevant doses studied.

Administration, Oral↗
PubMedDate not supplied

Understanding lesbians' mammography utilization.

Lesbians face unique barriers to health care, and may be at higher risk for breast cancer than are other women. Yet, no research on lesbians and mammography utilization exists. We conducted telephone interviews of 107 lesbians aged 51-80, of whom 68 had had mammograms in the last year and 39 had not. Responses to open-ended questions identified the barriers lesbians face in obtaining mammography, lesbians, reasons for obtaining mammograms, and factors that would help lesbians obtain mammograms. Some issues identified were particular to lesbians; many issues were common to those identified by general samples of women (which include lesbians).

Aged↗
PubMedDate not supplied

Effect of an 8-hour holding period on in vivo and in vitro properties of red cells and factor VIII content of plasma after collection in a red cell additive system.

Extension of the holding time for whole blood units from 6 to 8 hours at ambient temperature should provide enhanced flexibility in the preparation of platelet concentrates (PCs). A paired study was conducted to evaluate the characteristics of stored red cells (RBCs) and plasma prepared from whole blood collected into a red cell additive system (CPD-ADSOL) after an extended holding time. An individual donated a unit of whole blood on two occasions; 1 unit was held for 6 hours before processing and the other for 8 hours. Autologous RBC 24-hour survival levels after 42 days of storage were comparable. Laboratory A, using a 99mTc-51Cr technique, found mean survival levels of 79 percent (6-hour hold) and 78 percent (8-hour hold) (n = 8). Analysis by the single-label procedure found the mean levels to be 82 and 81 percent. Laboratory B, using an albumin 125I-51Cr technique, found mean survival levels of 74 and 72 percent (n = 10). Mean hemolysis and ATP levels were found to be comparable after 42 days of storage following 6- and 8-hour holding periods. 2,3 DPG levels were reduced to a greater degree during the longer hold. The factor VIII levels in plasma frozen for at least a month after 6- and 8-hour holding periods were comparable; thawed plasma contained mean levels of 0.77 and 0.76 units per mL (n = 21). These studies indicate that components prepared by using a CPD-ADSOL system after holding periods of 6 and 8 hours have comparable properties.

Blood↗
PubMedDate not supplied

Structure-response relationships in noctuid sex pheromone reception. An introductory report.

Electroantennogram (EAG) data reflecting response spectra of male pheromone receptors have been analyzed for 16 species of Noctuidae (Lepidoptera). The test compounds included 100 pheromone analogues, altered in chain length, in position and configuration of double bond(s), and in the functional end groups. On comparison of amounts of substance required to elicit an equivalent EAG response, a single compound was determined to be most effective on a given species: these structures, either known or proposed as the natural sex pheromones of the species, were cis-7-dodecen-1-y1 acetate, cis-7-tetradecen-1-y1 acetate, cis-9-tetradecen-1-yu acetate, trans-9-tetradecen-1-y1 acetate, cis-11-hexadecen-1-y1 acetate, cis-9, trans-12-tetradecadien-1-y1 acetate, cis-9-tetradecen-1-y1 formate, and cis-9-tetradecen-1-ol, respectively. Elongation (shortening) of the chain by 1 or 2 methylene groups, the movement of a double bond 1 carbon from the optimum, a change to the opposite geometrical isomer, or the introduction of a second double bond invariably reduced EAG responses to 1.8 to 56 times below that observed with the most stimulating compound, in all 16 species. Further alterations in chain length or in double bond position caused even greater reduction in activity, as did certain in end group (Tables I and II). A set of distinct rules could be derived from these structure-response relationships; one of these rules concerns the optimum position of the double bond(s) in relation to chain length, and another one the ratios in activity values produced by end group variations, irrespective of chain length. The same rules described here for 16 noctuid species held also for the structure-response relationships observed within various additional groups of Lepidoptera. From EAG values determined in this study, an attempt has been made to calculate physicochemical propteries of underlying acceptor structures.

Animals↗
PubMedDate not supplied

Attraction of ethyl ether extracts of 232 botanicals to oriental fruit flies, melon flies, and Mediterranean fruit flies.

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), the melon fly, Dacus cucurbitae Coquillett, and the oriental fruit fly, D. dorsalis Hendel, three Hawaiian tephritids of economic importance, were exposed to traps each containing one of 232 ethyl ether extracts of air-dried botanicals. The principal concern was to establish which extracts were attractive judged on the basis of an index determined by the number of times more flies were attracted to the trap baited with water and extract than were attracted to traps baited with water only. Female Mediterranean fruit flies were attracted to 61 extracts and melon fly females to 31 extracts. Female oriental fruit flies were not much attracted. Many extracts were attractive to males of the three species. The extract of Coffea robusta Linden (Family Rubiaceae) was the only material attractive to both sexes of all three species.

Animals↗
PubMedDate not supplied

Naturally occurring insect growth regulators. II. Screening of insect and plant extracts as insect juvenile hormone mimics.

Ethereal extracts prepared from the larvae, pupae, or eggs of 10 species of insects and from various parts of 343 species of higher plants were screened for juvenilizing effects against Tenebrio molitor and Oncopeltus fasciatus. Activity in both species was shown by an extract of the larvae of the stable fly, Stomoxys calcitrans, whereas an extract of the pupae was active in O. fasiatus only. Extracts of two plant species (Echinacea angustifolia roots and Chamaecyparis lawsoniana seeds) showed high juvenilizing activity in T. MOLITOR, AND EXtracts of five plant species (Clethra alnifolia stems, leaves, and fruits, Sassafras albidum roots and root bark, Eucalyptus camaldulensis stems and bark, Pinus rigida twigs and leaves, and Iris douglasiana roots, stems, and fruits) were highly active in O. fasciatus an extract of Tsuga canadensis leaves showed lower activity in this insect. Extracts of 16 species of plants showed high insecticidal activity (mortality) in O. fasciatus but lacked juvenilizing properties in both species of test insects.

Animals↗
PubMedDate not supplied

Naturally occurring insect growth regulators. III. Echinolone, a highly active juvenile hormone mimic from Echinacea angustifolia roots.

A compound, C14H24O2, which induces strong juvenilizing effects in the yellow mealworm, Tenebrio molitor L., following topical application to the pupal stage, was isolated in pure form from the roots of Echinacea angustifolia DC and tentatively identified as dextrorotatory (E)-10-hydroxy-4,10-dimethyl-4,11-dodecadien-2-one. The compound has been named echinolone.

Biological Assay↗
PubMedDate not supplied

No association between serum cholesterol and growth in preadolescent American children.

To determine the relation between serum cholesterol level (SCL) and growth in preadolescent children (2-12 years of age) in the United States, we examined the association of SCL and three measures of growth in a national sample of American children from 1971 to 1974. We investigated three parameters: sitting height, standing height, and weight and undertook separate analyses for sex and race. We found no consistent statistically significant associations with any of these three measures of growth. This result did not change when we adjusted the data for age alone or for age, poverty index, serum protein level, and hematocrit. We conclude that growth in this population group is not dependent on SCL.

Body Height↗