Elimination kinetics of plasma exchange

Interest in the therapeutic use of plasma exchange for various diseases is growing. The two different effects of plasma exchange are elimination and activation. The kinetics are linear for elimination by plasma exchange, but not for activation. Plasma exchange is performed intermittently and can be described by intermittent kinetics. According to intermittent kinetics, plasma exchange removes 50% to 75% of a substance in plasma within 1-2 h, corresponding to an elimination half-life of 30-40 min. Hybrid kinetics, a mixture of actually intermittent but theoretically continuous elimination by plasma exchange, can however also be applied. Hybrid kinetics are more convenient and more reliable than intermittent kinetics. This is because hybrid kinetics are based solely on the concentrations before each plasma exchange; hybrid kinetics also reflect removal from the entire body and not just from the plasma compartment. According to hybrid kinetics, the amount of a substance in the body removed within 3-4 days is 50% of the difference between the initial and the final plasma concentration, depending on the intensity of plasma exchange. The intensity may well contribute at least in part to the beneficial effect of plasma exchange in various diseases.

Influence of prostaglandin A1 on renal filtration, hemodynamics and excretion. Investigations in chronically instrumented conscious dogs on a low- and high-sodium diet

The effect on renal function of a 210-min infusion of PGA1 into the aorta of 10 conscious beagle dogs has been investigated. In the sodium-replete group, PGA1 caused an increase in the glomerular filtration rate (GFR) (24%), renal blood flow (17%) and sodium excretion (20%). By contrast, in the sodium-depleted group, PGA1 caused a considerable reduction of GFR (25%) and sodium excretion (51%). In this group, baseline renal blood flow was lower, and there was no further reduction during PGA1 infusion. Fractional sodium excretion was unchanged in the sodium-replete dogs, but was reduced in the sodium-deplete state. Plasma renin activity was markedly elevated and further increased in the sodium-deplete group, but it was nearly unchanged in the sodium-replete group. This difference in renal response to exogenous PGA1 might be due to interaction with the renin-angiotensin system, which was markedly stimulated by sodium depletion and additionally by prostaglandin infusion.

Incorporation of inositol hexaphosphate into red blood cells mediated by dimethyl sulfoxide

Inositol hexaphosphate (IHP) binds to deoxyhemoglobin and markedly decreases the affinity of hemoglobin for oxygen. We introduce here a method for incorporating this polyphosphate into erythrocytes, thus preparing very low affinity cells for use in respiration research. The method uses dimethyl sulfoxide (DMSO) to facilitate entry of IHP. The cells are exposed to a high concentration of DMSO which is rapidly diluted with IHP solution. During this dilution the cells become leaky and IHP enters. The influence of several variables at each step of the process has been investigated and the data support a transient osmotic gradient mechanism for IHP incorporation.

Influence of Prostaglandin A₁ on Renal Filtration, Hemodynamics and Excretion

The effect on renal function of a 210-min infusion of PGA₁ into the aorta of 10 conscious beagle dogs has been investigated. In the sodium-replete group, PGA₁ caused an increase in the glomerular filtration rate (GFR) (24%), renal blood flow (17%) and sodium excretion (20%). By contrast, in the sodium-depleted group, PGA₁ caused a considerable reduction of GFR (25%) and sodium excretion (51%). In this group, baseline renal blood flow was lower, and there was no further reduction during PGA₁ infusion. Fractional sodium excretion was unchanged in the sodium-replete dogs, but was reduced in the sodium-deplete state. Plasma renin activity was markedly elevated and further increased in the sodium-deplete group, but it was nearly unchanged in the sodium-replete group. This difference in renal response to exogenous PGA₁ might be due to interaction with the renin-angiotensin system, which was markedly stimulated by sodium depletion and additionally by prostaglandin infusion.

Demonstration of cerebrospinal fluid oligoclonal banding in neurologic diseases by agarose gel electrophoresis and immunofixation

Demonstration of an oligoclonal immunoglobulin pattern in cerebrospinal fluid by a commercial agarose gel electrophoresis system and immunofixation were evaluated in the service clinical laboratory of a university hospital. In 303 patients, 45 with clinically definite multiple sclerosis and 209 with other neurologic diseases, the sensitivity of oligoclonal banding for multiple sclerosis was 71%, and the specificity, 83%. Oligoclonal banding was frequent in inflammatory disease, tumor/pseudotumor or vascular diseases of the central nervous system (35%, 36% and 26%, respectively) and less frequent in degenerative central nervous system disease and peripheral neuropathy (5.2% and 15%). No patient with non-neurologic disease had oligoclonal banding. The addition of an immunochemical step (immunofixation) did not increase sensitivity and only minimally increased specificity. It did permit distinction in selected cases between immunoglobulin and other molecules with identical electrophoretic mobility.

Influence of Prostaglandins A_1, E₁, E₂, and F_2α on Renal Blood Flow and Plasma Renin Activity

The effects of different prostaglandins (PG) on serial determinations of renal blood flow (RBF), mean arterial blood pressure (MABP), renal vascular resistance (RVR) and renin release were investigated in the conscious, chronically instrumented dog. 2 months after right-sided nephrectomy, female beagle dogs (n=6) were implanted with an electromagnetic flow probe and an inflatable pneumatic cuff around the left renal artery, and a catheter was inserted into the aorta above the renal artery. In repeated experiments, different prostaglandins (PGA_1, E₁, E₂ and F_2α) were infused above the renal artery at increasing doses (infusion time 15 min, doses 0.03–1.0µg min^-1 kg^-1). Lower and medium doses induced an increase of RBF, which returned to or were slightly below control levels with higher doses. PGA, appeared to be the most potent vasodilator with a significant hypotensive activity and the greatest augmentation of RBF. Simultaneously, renin release was most pronounced by PGA,.

Inhibition of anti-inflammatory drugs of prostaglandin production in cultured macrophages

1. A sensitive, simple, reproducible, and economical assay for structure-activity investigations of non-steroidal anti-inflammatory drugs (NSAID) is lacking. This has prompted us to investigate the advantages and limitations of defining for that purpose the potency of NSAID's as inhibitors of tumour promoter-induced prostaglandin (PG) release from mouse peritoneal macrophages in culture. 2. These cells release mainly PGE2 and PGI2 (measured as its stable hydrolysis product 6-keto-PGF1 alpha) upon stimulation with the tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). 3. The PG release was dose-dependently inhibited by a variety of NSAID's. Their inhibitory potency was dependent on the culture conditions employed. The widely used acidic NSAID's were more potent when assayed under serum free culture conditions at low pH. 4. Dose response curves for acidic NSAID tested under serum free conditions allowed for the definition of IC50 values being reproducible within their 95% confidence limits. 5. The IC50 values obtained for different standard acidic NSAID's varied within 4 orders of magnitude. They corresponded favourably to their clinical potency and their potency in a variety of standard tests for anti-inflammatory drugs. 6. IC50 values of five congeners of indomethacin differed up to 2 orders of magnitude in agreement with in vivo observations indicating the applicability of this assay for structure-activity investigations.

[A report on the syndroma of narrow spinal canal at congenital chondrodystrophy (author's transl)]

It is reported on a case of congenital chondrodystrophy associated with a narrow spinal canal. The difficulties in diagnosis are pointed out and electromyography is marked to enlarge the diagnostic possibilities in such patients. In cases with clinical signs of spinal--or nerve nerve root compression, complete laminectomy is indicated.

Prostaglandin release from macrophages: an assay system for anti-inflammatory drugs in vitro

It is the intention of this communication to present a simple and reliable in vitro system for the evaluation of anti-inflammatory drugs. The system described appears to combine the advantages of two established procedures, i.e. measurement of the inhibition of prostaglandin (PG) synthesis in vitro using microsomal enzyme preparations and the measurement of the inhibitory effects of drugs on PG synthesis in vivo avoiding major limitations. We propose to measure the effect of drugs on the PG release from mouse peritoneal macrophages in vitro. The influence of culture conditions, phagocytosis and drugs on the PG release from these cells is described. We found that antibody-coated erythrocytes are especially suitable triggers of PG release, and that the release can be inhibited by steroidal and non-steroidal anti-inflammatory drugs in concentrations resembling their effective doses in vivo.