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Biomedical subjects

J S Schultz

Publications and source records attributed to J S Schultz.

At least 73 records · Page 4Linked to original sources
PubMed1971

Passive asymmetric transport through biological membranes.

The magnitude of passive diffusional solute transfer through artificial membranes is usually considered to be independent of the direction of the concentration gradient driving force. It can be shown, however, that a composite membrane, having as one component a membrane with a chemical reaction-facilitated diffusion transport mechanism, can result in an asymmetrical flux. An asymmetric flux caused by this type of structural heterogeneity may be one mechanism contributing to the asymmetric properties of biological membranes. Similar vectorial fluxes can be generated in interfacial solute transfer through membranes if hydrodynamic boundary layers occur at the membrane interface and reversible chemical reactions with the permeant species are involved in either phase.

Biological Transport↗
PubMed1970

Studies of Lp-lipoprotein as a quantitative genetic trait.

Sera from 11 individuals which were classified as Lp(a-) by direct gel diffusion and by absorption tests showed the presence of Lp(a) lipoprotein when the sera were concentrated 120-fold. This Lp(a) antigen was demonstrated by gel diffusion to be indistinguishable from Lp-lipoprotein isolated from known Lp(a+) sera. The Lp(a) preparations from sera classified Lp(a-) also showed electrophoretic mobility in immunoelectrophoresis and schlieren diagrams in ultracentrifugal analyses similar to Lp-lipoprotein from Lp(a+) sera. The proposal is made that observed individual variations in tests for the Lp-lipoprotein reflect a quantitative genetic trait and that it is likely that different individuals produce Lp-lipoprotein in widely varying amounts. The consistency of this proposal with certain previous observations on the Lp system is discussed.

Antigens↗
PubMed1967

Differential dialysis culture for separation and concentration of a macromolecular product.

A differential dialysis flask, constructed with three chambers and two membranes of different porosity, was used to effect the separation and concentration of enterotoxin B produced extracellularly by a culture of Staphylococcus aureus. Variables were examined that affected the diffusion of glucose, as measured by half-equilibration time and permeability coefficient; the relative chamber volume, type of membrane, membrane masking, and mixing all exerted a substantial influence on diffusion rates. A number of membrane filters were tested for usefulness; one type, made with vinylidene fluoride, had desirable physical and diffusional properties, but neither it nor others consistently withheld the bacteria for more than a marginally useful period of about 50 hr. In ordinary two-chambered dialysis culture, the amount of enterotoxin reached 10 times that in control culture; in differential, three-chambered dialysis culture the comparable factor of increase was about 7, with about two-thirds of this amount being separated from cells in the product chamber of the flask.

Dialysis↗
PubMedDate not supplied

Reiter's syndrome following Shigella flexneri 2a: a sequel to traveler's diarrhea. Report of a case with hepatitis.

Shigella flexneri 2a was isolated from a patient with Reiter's syndrome (RS) following a family outbreak of traveler's diarrhea. Among 3 members at risk, only the patient was positive for HLA-B27. Data from 3 similar families support the hypothesis that susceptibility to RS is genetically transmitted. It is urged that every effort be made to culture and subtype Shigella and other enteric pathogens in RS following diarrhea. Concurrently, the patient had hepatitis, interpreted as a parallel enteric infection.

Adult↗
PubMedDate not supplied

Initial treatment of glaucoma: surgery or medications.

Should surgery or medications be the initial therapy for primary open angle glaucoma? In this set of articles, Drs. Sherwood, Migdal, and Hitchings present evidence suggesting that filtration surgery provides better intraocular pressure control than does medical treatment, good (or better) visual field preservation, and visual acuity as good as that in medically treated fellow eyes. They also cite cost effectiveness, quality of life, and possible adverse effects of medical treatment on future surgery. Drs. Sharir and Zimmerman, on the other hand, favor initial medical therapy, questioning the validity of some reports on surgical results, citing the risks of complications, and noting recent and current progress in the development of antiglaucoma medications. Dr. Schultz' editorial evaluates both points of view, concluding that additional prospective randomized tests may be useful and that either approach may be a viable option, as long as it is individualized to each particular patient.

Acetazolamide↗
PubMedDate not supplied

The combinatorial library: a multifunctional resource.

About 10 years ago Dr. Mario Geysen introduced a method for synthesizing a large number of peptides on solid supports simultaneously. This work has subsequently been generalized by many other research groups to develop technologies that allow from hundreds to thousands to millions of compounds to be synthesized in parallel. These large collections of compounds have been now termed combinatorial libraries. Much of the effort in this field has been directed to drug discovery. However, in recent years, these libraries have been shown to be very useful for finding compounds (such as inhibitors, binding agents, enzymes, and antibodies) that satisfy specific requirements. Thus these techniques represent a very excellent resource for the discovery of compounds for a variety of biotechnological process needs.

Amino Acid Sequence↗
PubMedDate not supplied

Affinity sensor: a new technique for developing implantable sensors for glucose and other metabolites.

We describe affinity sensors for monitoring various metabolites in blood plasma by optical means. The principle of detection is similar to that used in radioimmunoassays and is based on the competitive binding of a particular metabolite and a fluorescein-labeled analogue with receptor sites specific for the metabolite and the labeled ligand. This concept has been directed toward the development of an affinity sensor for glucose. Concanavalin A, a protein with specific binding character for glucose, was immobilized on the inside surface of a hollow dialysis fiber. Fluorescein-labeled dextran was selected as the competitive labeled ligand. The molecular weight cutoff of the dialysis fiber is low enough to completely retain the 70,000 MW dextran within the fiber lumen while glucose can freely pass through the dialysis membrane. The sensor is completed by inserting a single optical fiber in the lumen of the dialysis fiber, thus allowing measurement of the unbound FITC-dextran. Preliminary tests of the sensor indicated the feasibility of the approach. Sensitivity to glucose in the physiologic range was obtained, but further work will be required to optimize the sensitivity and response time of the sensor.

Blood Glucose↗