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Biomedical subjects

D D Lobdell

Publications and source records attributed to D D Lobdell.

8 recordsLinked to original sources
PubMed1994

A treatment system for implementing an extracorporeal liver assist device.

Biologically active devices are receiving increasing attention, especially in the management of endocrine pancreatic failure (diabetes) and acute liver failure. In both instances, mechanical devices have been unable to replace the function of the original organ, and consequences range from inconvenient (e.g., regular insulin shots, diabetic vasculopathy) to fatal (e.g., fulminant hepatic failure). In developing a cell-based liver assist device, we concluded that currently available extracorporeal blood treatment systems are not suited to the delivery of high molecular weight substances and that they do not adequately address the metabolic needs of the device. We therefore developed a system that provides safe, continuous perfusion of an extracorporeal organ. We detail the design and first clinical use of the system.

Animals↗
PubMed1993

Research benefits.

Explore the source record for details and available documents.

Costs and Cost Analysis↗
PubMed1991

Extracorporeal methods in lipid reduction pursuant to improvement in risk factors associated with atherosclerosis.

Atherosclerosis is the leading cause of death in the United States. Elevated plasma levels of low-density lipoprotein and lipoprotein(a) [Lp(a)] and subnormal levels of high density lipoprotein are risk factors in atherosclerotic coronary heart disease. Extracorporeal methods of affecting these risk factors are reviewed. The limited information on the effects of apheresis procedures on Lp(a) is discussed and extended from a kinetic modeling approach. An estimate, made of the number of patients who could be expected to benefit from extracorporeal lipid lowering, is presented.

Arteriosclerosis↗
PubMed1988

Reduction of low-density lipoproteins with dextran sulfate in patients with familial hypercholesterolemia.

A novel on-line system for the selective precipitation of low-density lipoprotein (LDL) using dextran sulfate has been devised and tested in four patients with heterozygous familial hypercholesterolemia (type II). The mean pretreatment serum cholesterol was 410 mg/dl. Plasma was generated by membrane filtration and LDL and VLDL (very-low-density lipoprotein) were completely precipitated with 10-35 mg% dextran sulfate (Mr 5,000) in the presence of 55 mM Ca2+. The precipitate was removed by filtration and the excess Ca2+ by dialysis. For 41 procedures the mean reduction of plasma solutes was LDL + VLDL 65%, HDL 23%, fibrinogen 19%, albumin 15%, IgG 20%, IgA 19%, IgM 24%. We conclude that dextran sulfate precipitation is an effective method for selective on-line removal of LDL from plasma.

Adult↗
PubMed1988

Treatment of hypercholesterolemia by precipitation of lipoproteins with dextran sulfate.

An on-line continuous system for the selective precipitation of low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL) has been devised and tested. This system conserves high-density lipoproteins (HDL) and other plasma macromolecules. LDL and VLDL are precipitated from plasma using 10-35 mg/dl dextran sulfate (Mr 5,000) in the presence of 55 mM calcium with a reduced concentration of monovalent cations. The plasma is obtained by membrane filtration of whole blood using the COBE Centry TPE System (Cobe Laboratories Inc, Lakewood, Co.). The precipitated LDL plus VLDL is removed by filtration, and the electrolytes are restored by dialysis. The plasma minus LDL plus VLDL is then returned to the patient. Four patients with heterozygous familial hypercholesterolemia (type II) were treated 70 times. The mean pretreatment serum cholesterol was 383 mg/dl. The mean reductions in plasma components were: LDL plus VLDL 63%; HDL 27%; fibrinogen 19%; albumin 15%; IgG 20%; IgA 19%; IgM 25%; C3 30%; and C4 27%. The cholesterol returned to near normal values in approximately 2 weeks after each treatment. Four normal volunteers were each treated one time. These individuals had a mean pretreatment serum cholesterol of 201 mg/dl. The mean reduction in plasma components were: LDL plus VLDL 70%; HDL 27%; fibrinogen 24%; albumin 14%; IgG 18%; IgA 17%; IgM 20%; C3 27%; C4 22%; C3 proactivator 12%; alpha 1-antitrypsin 17%; ceruloplasma 17%; transferrin 18%; alpha 2-macroglobulin 17%; and orosomucoid 13%. It is our conclusion that dextran sulfate precipitation is an effective on-line means of selectively removing LDL plus VLDL from plasma while conserving HDL and other plasma macromolecules.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1981

An invertible simple equation for computation of blood O2 dissociation relations.

An equation that will represent blood O2 dissociation relations over the saturation range of 0-100% and be invertible is presented. The Hill equation is contained as a special case of this form. Determination of the four parameters of the equations by standard dissociation curves presented by Severinghaus gives an equation of improved accuracy when contrasted to previous treatments. A program for use of this equation with certain hand-held calculators is available.

Humans↗
PubMed1976

Calculations for pH during CO2 and O2 exchange with blood.

New mathematical formulas are presented to calculate directly the change in blood pH during CO2, and O2 exchange with blood. pH changes are calculated from changes in blood PCO2 and saturation values or from changes in blood PCO2 and blood PO2 values. Computational results agree well with information obtained from a Dill nomogram. These new formulas have applicability to the modelling of gas exchange in blood oxygenators as well as to estimating blood acid-base parameters following the mixing of blood samples.

Blood↗