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Biomedical subjects

D Shafer

Publications and source records attributed to D Shafer.

9 recordsLinked to original sources
PubMed1992

Immunomagnetic separation of tumor necrosis factor alpha. I. Batch procedure for human temporomandibular fluid.

A batch separation procedure has been developed for retrieval of tumor necrosis factor (TNF) alpha from the microliter volumes of fluid isolated from the human temporomandibular joint (TMJ). Paramagnetic beads coated with monoclonal antibodies for TNF were used. The beads, and bound TNF, were recovered from solution with the aid of a magnetic field. The amount of bead-bound TNF was quantified using an immuno-based assay developed in this laboratory called the cluster assay. The cluster assay was specific for TNF and linear up to 10 ng. Using these methods we found that TMJ fluid contained 0.2-4.2 ng per 100 microliters of fluid with a mean value of 1.9 ng and a standard deviation of 1.1 ng. This study demonstrates the utility of batch immunomagnetic separation for the concentration and purification of proteins, and the cluster assay for quantification of proteins from microliter volumes of body fluids.

Antibodies, Monoclonal↗
PubMed1992

Identification of apoB-containing lipoprotein families in NIDDM.

The purpose of this study was to determine the concentrations and composition of apoB-containing lipoprotein families in whole plasma and major lipoprotein density classes of a selected group of Native Americans from northeastern Oklahoma with non-insulin-dependent diabetes mellitus. The measurement of lipoprotein density classes showed that the total lipoprotein mass of very-low-density lipoproteins was significantly higher and that of high-density lipoproteins significantly lower in diabetic patients than nondiabetic control subjects regardless of their plasma triglyceride levels. The VLDLs were enriched with TG, free cholesterol, and apolipoproteins C-III and E. HDLs were enriched with TG but depleted of apoC-III and apoE. There was no change in the levels of TG-enriched low-density lipoproteins. Fractionation of VLDL by sequential immunoprecipitation with antisera to apoE and apoC-III established that increased concentrations of this density class in diabetic patients are due to elevated levels of TG-rich lipoprotein LP-B:C and lipoprotein LP-B:C:E. The levels of LP-B:C particles were increased more than the levels of LP-B:C:E particles. The LDLs were characterized by a slight increase in TG-enriched lipoprotein B and no change in the levels of LP-B:C and LP-B:C:E. There was no difference between diabetic patients with or without vascular disease in the levels of LP-B and LP-B:C:E. However, patients with vascular disease had higher concentrations of LP-B:C particles in VLDL and whole plasma than patients without vascular disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Degradation of dimethyl nitrosamine by Methylosinus trichosporium OB3b.

The degradation of dimethyl nitrosoamine (DMNA) by a methanotroph, Methylosinus trichosporium OB3b, was studied using 14C-labelled DMNA. The organism was capable of assimilating DMNA-carbon and converting it to CO2. The rates of CO2 production (VCO2) from DMNA and its cellular uptake (VP) were linearly correlated with DMNA concentrations of 0.03-10 mM, which corresponded to approximately 3% of added DMNA metabolized in 24 h. These rates were two to three orders of magnitude less than the rate of uptake of methane (VCH4. VCH4 was suppressed when the concentrations of DMNA exceeded 0.3 mM. In the presence of 0.1 mM DMNA, VP and VCO2 were essentially the same in the presence or absence of methane in the first 8 h of incubation, but declined sharply thereafter only when methane was absent. These observations suggest that the metabolism of DMNA was carried out by methane monooxygenase (MMO), and that NADH, a cofactor for MMO, may be provided by the oxidation of the stored compounds in the cells when methane is not available.

Biodegradation, Environmental↗
PubMed1985

Morphine depression of T cell E-rosetting: definition of the process.

Two kinetic assays were developed to assess opiate effects on rates of T cell E-rosetting. The first adopted the thermal conditions of active E-rosetting assays (varying between 37 and 23 C) whereas the second incorporated cooler thermal conditions (varying between 0 and 29 C). In vitro treatment of lymphocytes with morphine depressed E-receptor levels and E-rosetting in both assays. With the 0-29 C procedure early stages of E-rosette formation were characterized by phase transition kinetics indicative of sequential gain and loss of E-rosettes. Assay thermal and erythrocyte (E) to T cell contact conditions, and the inclusion of morphine during E-rosetting, were independent variables that coordinately modulated the expression of phase transitions. Phase transitions were also noted during capping of total T cell E-rosettes at 37 C. The reason for phase transitions appears to be that T cells undergo sequential cycling of E-receptors, increasing because of the new expression of dormant E-receptors as the result of E-receptor microdisplacement and decreasing because E-rosettes are lost owing to patching and capping processes. According to this construction of the E-rosetting process, morphine inhibits E-rosetting and modulates expression of phase transitions by interfering with E-receptor microdisplacement processes. Presumably this interference by morphine is mediated through alteration of membrane fluidity and promotion of E-receptor coupling (and/or inhibition of uncoupling) to a transducer-effector component within the cell membrane. These findings and conclusions are specifically relevant to immunoregulatory processes and are also helpful for understanding the general nature of biological and physiological responses associated with receptor-ligand interactions.

Erythrocytes↗
PubMed1978

Retinal embolization from endocarditis.

Arterial emboli, fragmentation of both the arterial and venous blood columns, and bilateral cherry red spot were seen in the fundus of a patient with progressive onset of visual loss. Initially, the patient, a 56-year-old housewife, was thought to have temporal arteritis. Her clinical condition worsened on steroids which was subsequently discontinued when 5 out of 6 blood cultures were reported positive. Showers of microemboli were responsible for her unusual fundus findings.

Arteritis↗