DE3643348A1 - THERMAL FILTRATION OF PLASMA - Google Patents

Description

The present invention relates to filtration of macromolecules from fluids and in particular the removal of unwanted macromolecules from plasma solutions by the process known as thermofiltration.

The separation of unwanted solutes from blood plasma by plasma filtration is a known method for the treatment of diseases, such diseases usually undesirably high levels of solute Substances in plasma or plasma admixtures (hereinafter referred to as plasma admixtures), such as Toxins, excess antibodies and other metabolic factors. Successful treatment of such diseases involves removing the unwanted Plasma admixtures from the blood plasma by membrane filtration.

Various plasma filtration devices, including cascade filtration, double filtration and cold filtration have been developed. This procedure but contain a number of undesirable properties, that limit their use.

A number of parameters have been demonstrated which can be compared with the Performance, the module design, the Membrane properties, plasma composition and Include plasma and filtration temperature. properties of the module that the fluid dynamics and in turn affect performance, include the Area, fluid and film dimensions, just like that Properties of the separating membrane, including the Type of polymer and microstructural features such as pore size, pore curvature, pore length and number of pores.  

Affect changes in the composition of the plasma also its filtration. Plasma from patients with different disease states or with different Macromolecule content has different Filtration properties. Manipulating the plasma, changes in pH or electrolyte composition to effect and the addition of anticoagulant Substances such as heparin and others that are macromolecular aggregating additives such as polyethylene glycol affect the filtration performance. In general such manipulations are carried out to the separation one or a group of solutes from the Plasma by macromolecular aggregation or precipitation reinforce.

Because of the number of parameters that affect the filtration performance It was demonstrated that the Temperature selection and its regulation is a key parameter is in fluid separation. To selective removal to reinforce in a particular macromolecular area, it is extremely important within a special Temperature range to work. In this There were remarkable differences for comparable relationships Filtration conditions (similar working flows, Modular types and plasma types) between Cascade and double filtration that are close to ambient temperatures work, and cold filtration observed at temperatures below a set physiological temperature work.

Temperature control shows many advantages over other parameters by controlling the temperature of the am easiest to control physical parameters is and by using the temperature control with a Variety of complexing agents can be combined to to increase the sensitivity of macromolecule removal.  

A specific example of this can be in the case of cold filtration are shown, in which the addition of Heparin due to the formation of a cold gel (cryogel) Formation of a complex with fibronectin and fibrinogen helps at temperatures below 25 ° C.

Filtration at a temperature below the physiological Temperature is for the removal of plasma components effective that are similar in size however differ in temperature sensitivity. A Number of autoimmune diseases can be treated in this form as described in the literature. Education and contributes to the effectiveness of this treatment Removal of cold gel from high concentrations of the macromolecules composed with are linked to the autoimmune disease states. As a result, the separation is based on cold filtration not on the molecular size at physiological temperature but on the molecular size at reduced temperatures.

Operation at reduced temperature can, however actually reduce the selectivity of molecular separation, if the size differences are big, because the aggregation or complexation of small molecules can also occur at reduced temperatures. Consequently, it can be for the separation, which is due to the size differences based on physiological temperatures, be more advantageous to avoid cold gel formation.

It is therefore an object of the present invention to provide a improved device for removing unwanted macromolecules from fluids in an effective and powerful Way to create.  

In one aspect, the present invention relates on a device for the selective removal of macromolecules from a plasma solution that is creating a plasma solution that contains the macromolecules to be removed contains, the heating and / or holding the Plasma solution at a temperature near or above that Normal body temperature but below the boiling point of the Plasma solution and the filtration of the heated plasma solution during a temperature near or above that Normal body temperature but below the boiling point with a membrane filter encloses to macromolecules more selective to remove from the plasma solution. In addition can be different by heating the plasma solution Macromolecules present in the plasma solution be inactivated or denatured, leading to their selective Removal by plasma filtration helps.

Another aspect relates to the present Invention on a selective removal device of macromolecules from a plasma solution that the Securing a blood flow from a Sample, separating the blood flow into a concentrated Cell element stream and a plasma stream that contains the macromolecules to be removed, the heating or holding the plasma flow that is to be removed Contains macromolecules at a temperature near or above normal body temperature below their boiling point, filtering the heated Plasma current during a temperature near or above normal body temperature but below hers Boiling point with a membrane filter to the macromolecules more selective to remove from the plasma solution to to form a filtered plasma stream, connecting the filtered plasma stream and the cell element stream, to form a treated plasma stream, and cooling and / or returning the treated  Includes plasma flow to samples.

Another aspect relates to the present Invention on a device for regulating the conditions the lipoprotein abnormalities in a living organism by selective removal of macromolecules from a Plasma solution that ensures blood flow from a living organism, the separation the flow of blood into a concentrated stream of cell elements and a plasma stream that contains those to be removed Contains macromolecules that warm or hold the Plasma stream that contains the macromolecules to be removed contains, at a temperature near or above that Normal body temperature but below its boiling point, filtering the heated plasma stream during a temperature near or above normal body temperature but below its boiling point a membrane filter to remove the macromolecules from the Remove plasma solution more selectively to a filtered To form plasma stream, connecting the filtered Plasma flow and the cell element flow to a treated plasma flow to form, and cooling and / or returning the treated plasma stream to includes living organism.

Another aspect relates to the present Invention on a device for more selective removal of macromolecules from a plasma solution, which includes: a facility for reception and division a plasma-containing solution that contains macromolecules obtained from a sample into a concentrated one Cell element stream and a plasma stream, a Device for receiving, warming and / or keeping the Plasma flow at a temperature near or above the normal body temperature, but below its boiling point, a facility for recording and filtering  of the heated plasma flow to the macromolecules to selectively remove a facility to accommodate the filtered plasma stream from the filter device and for receiving the concentrated cell element stream and to connect these streams to a treated stream to form that essentially of the macromolecules, that should be removed, is free, and set up for receiving and / or cooling the combination stream to normal body temperature to get this fluid to the Samples attributed.

The following is a brief description of the drawings, for the purpose of illustrating the invention being represented.

Fig. 1 shows the circuit used in in vitro filtration;

Figure 2 shows the extracorporeal circuit used in ex vivo or clinical filtration;

Figure 3 shows the amount of cholesterol removed at changed temperatures for in vitro filtration;

FIG. 4 shows the mean screening coefficients for various types of plasma (module of the Kuraray Eval 4A type, in vitro at 37 ° C.);

Fig. 5 shows the particle size distribution of lipoprotein for FHC plasma and dog plasma with different cholesterol values; and

Figure 6 shows post-treatment recovery in a dog with LDL-VLDL and HDL cholesterol.

It was found to oppose the thermofiltration conventionally known methods of plasma filtration shows many advantages. Thermofiltration is removal of macromolecules from plasma by heating the Plasmas to a selective temperature near or above normal physiological temperature, however not above its boiling point, and filtering the heated plasma with a membrane filter with a Porosity that remove the desired macromolecules becomes. The critical benefits of thermofiltration be represented include the ability to much larger plasma volume at higher temperatures filter because plasma is exposed to higher temperatures will have a lower tendency to rain unwanted solutes on the membrane media form, and the more selective removal of macromolecules, based on the differences in the screening coefficients based at higher temperatures.

The evaluations of a large number of membrane filters Plasma filtration, based on the filter material, the Pore size and structure show that the module from Type Kuraray Eval 4A (copolymer of ethylene and vinyl alcohol, Kuraray Co., Japan) and other modules more similar Properties for fractionation of plasma admixtures by thermofiltration are particularly well suited. Other suitable filters include those that have a filter media use that made of polysulfone, polypropylene, Nylon, polyester, cellulose acetate, collagen and the like consists.  

It has been demonstrated for the Kuraray Eval 4A module that the sieving coefficients of some macromolecules 37 ° C and 42 ° C are remarkably higher than at 25 ° C. (Table I below) are particularly noteworthy higher screenings of HDL cholesterol, IgG, fibrinogen, Total protein and albumin at 37 to 42 ° C. In addition can as a result of reducing cold gel formation a much larger one at these higher temperatures Plasma volumes are filtered. The reason for this is that near or above normal physiological temperatures the aggregation of the solute is kept to a minimum and the separation to the Differences in the molecular size of the solutes and is not based on the aggregate compositions.

Table I

Screening coefficients for different macromolecules

All macromolecules come from the same plasma source. Heparin dosage: 1000 U / L.

TP: total protein, Alb: albumin, Glb: globulin, Fib: Fibrinogen, T Chol: total cholesterol, LDL: lipoprotein low density, HDL: high density lipoprotein, TG: Triglycerides.

In addition, thermofiltration is an effective one Process for removing pyroglobulins from plasma solutions. Pyroglobulins are serum globulins that occur during failing to heat or gelling. Usually do not become pyroglobulins in sera from normal individuals found. They become rather easy with macroglobulinemia and other lymphoid proliferative or multiple bone marrow disorders connected.

Warming up a serum that contains pyroglobulins 55-56 ° C results in the formation of a gel that the serum can be effectively removed by plasma filtration can. Similarly, proteins and other immunoglobulins, that effectively denature or coagulate when heated, also effectively removed by thermofiltration will.

As a consequence of the above advantages of Thermofiltration compared to conventionally known processes Plasma separation can be thermofiltration used to contribute to pathological macromolecules connected and not connected plasma treatments selectively to separate from blood while at the same time Passage or return of beneficial plasma proteins is allowed. The advantage of this type of treatment can be clearly shown in the therapeutic cholesterol regulation will.  

Cholesterol has been determined to be an important component arterial buildup in atherosclerosis just like with hypercholesterolemia. cholesterol circulates in the blood, linked to large protein molecules. A form of cholesterol that carries protein called Is called low density lipoprotein (LDL) known to promote atherosclerosis. A little 2/3 or more of all blood cholesterol is in LDL transported. Another form called lipoprotein High density (HDL) is called protection against known this disease process. That is why selective removal of LDL and maintenance of HDL in the treatment of arteriosclerosis and the therapeutic regulation of hypercholesterolemia important.

Recently, a plasma exchange has been in place for removal of plasma and its replacement with electrolyte solutions and / or family-related plasma products Hypercholesterolemia patients used. This procedure however, are not selective and remove lipoproteins low density (LDL) dosed with lipoproteins high density (HDL) and other plasma proteins used for are beneficial to the patient. In addition, various Process for the selective removal of LDL studied, including anti-LDL antibody Sepharose columns and combinations of heparin precipitation and bicarbonate dialysis, membrane filtration, however, shows in in terms of biocompatibility and treatment costs and effectiveness against these processes many Advantages.

The selective removal of LDL cholesterol from plasma by thermofiltration both under in vitro and can also be detected under ex vivo conditions. In vitro refers to experimental conditions that are in a  Laboratory, whereas ex vivo Conditions of extracorporeal circulation with living Organisms.

I. in vitro filtration

Various types of plasma are used in vitro to evaluate the temperature effect on selective cholesterol removal. The in vitro filtration tests are carried out with various types of plasma at variable temperatures in accordance with the extracorporeal circuit shown in FIG. 1.

In Fig. 1, one unit per ml of heparin (heparin-sodium injection, Invenex Lab., OH) is added to the plasma container 10 by keeping the plasma at about 37 ° C. by the heat controller 12 and a magnetic stirrer 14 . The plasma is withdrawn from the plasma container 10 into the line 16 and fed into the plasma pump 18 at a flow rate of 15 ml / min. The plasma is pumped from the plasma pump 18 into the line 20 and then into the water bath 22 , which is regulated by a heat controller 24 . Within the water bath 22 , the plasma flows through the heat exchanger 26 and flows through the pressure gauge 28 into the filter 30 , where the LDL cholesterol is retained and the HDL cholesterol and albumin essentially pass through. The filtered plasma without LDL cholesterol flows out of the filter 30 through the line 32 into the filtrate collecting tray 34 .

The following specific examples illustrate the Application of the present invention further.  

example 1

Family-linked type II hypercholesterolemia plasma (FHC) was obtained by repeated centrifuge plasma exchange. The in vitro filtration tests were carried out with the FHC plasma and the Kuraray EVAL 4A membrane filter at temperatures of 4, 25, 37, 42 and 47 ° C. in accordance with the extracorporeal circuit shown in FIG. 1 and described above. The mean screening coefficients ( SC ), the plasma volume treated and the total amount of LDL and HDL cholesterol were determined at the above temperatures according to the following calculations. wherein a sieving coefficient of 0.9 to 1 indicates little or no separation or removal of the macromolecule from the plasma and a sieving coefficient of 0 to 0.1 indicates essentially the total removal of the macromolecules from the plasma.

Amount of removal (g) = concentration in the plasma container (g / dl) × (1- sc ) × treated volume (dl)

Results

Table II shows the volume treated and the mean Screening coefficients for total cholesterol, HDL Cholesterol, LDL cholesterol and albumin in variable Temperatures. The results show that more than  85% of total cholesterol and 90% of LDL Cholesterol was removed while more than 70% Albumin and 60% of the HDL cholesterol through the filter went through. The screening coefficients of HDL Cholesterol and albumin increased with increasing Temperature, while LDL cholesterol is temperature independent was.

Table II:

Mean sieving coefficients and treated plasma volumes at different temperatures, in vitro filtration test of Kuraray Eval 4A (1.0 M specific surface area) using family-bound hypercholesterolemia plasma

Fig. 3 illustrates that the cholesterol removal is different at different temperatures. At 37 to 42 ° C, the amount of LDL cholesterol removed is greatest (4.5 g module), while HDL cholesterol is below 0.1 g. The distance per module was limited by the permitted maximum value P _tm (300 mm Hg (399 mbar)).

Conclusion: Thermofiltration is under in vitro conditions in the selective removal of large Amounts of LDL cholesterol from plasma very effective, while large amounts of the valuable HDL cholesterol and Albumins are maintained. In vitro membrane filtration of FHC plasma allowed with the Eval 4A filter almost complete reluctance of LDL High screening cholesterol or maintaining HDL Cholesterol and albumin. The sieving coefficients of HDL cholesterol and albumin increased with increasing Temperature while the sieving coefficient of LDL- Cholesterol almost a complete at all temperatures Reluctance was. Consequently, membrane filtration improves near or above the physiological Temperatures, and that is thermofiltration, which Selectivity versus removal of LDL cholesterol that of HDL cholesterol and albumin.

In addition, thermofiltration also allows larger plasma volumes to be treated. This is a Result of the reduction in cold gel formation and less removal of the solutes at increased Temperatures should not be removed. Per Module units are also larger volumes of plasma treated, and larger amounts of cholesterol away.

Example II

In vitro module filtration tests were carried out in accordance with the extracorporeal circuit described in FIG. 1 and above at 4, 25, 37, 42, 47 and 52 ° C. using Eval 4A (copolymer of ethylene and vinyl alcohol, specific surface area 2.0 m ² ) with normal human plasma (NHP) and sclerotic cholangitis plasma (SCP). The NHP was obtained by filtering outdated citrated plasma at 37 ° C using the Toray PS-05 type plasma separator (polymethyl methacrylate, specific surface area 0.5 m ² , Toray Industries, Japan). The SCP was obtained by membrane plasma exchange. The SCP differed from the NHP in that the SCP had 1.5 times higher fibrinogen and four times higher LDL cholesterol concentrations with similar levels of albumin and antithrombin III when compared to NHP.

All filtration experiments were carried out with a plasma flow of 30 ml / min. Changes in Inlet pressures were a function of transmembrane pressure recorded and reflect the membrane clogging again.

The samples obtained before and after filtration were analyzed for a variety of dissolved biochemicals, including albumin (Alb), fibrinogen (Fib), total cholesterol (T Chol), LDL cholesterol (LDL Chol), HDL cholesterol (HDL Chol), Antithrombin III (AT III) and heparin. Alb was measured using the bromcresol green method with an automatic analyzer (SMA-II, Technicon Instrument Co., Tarrytown, NY). Fib was measured using the Fibrosystem (BBL, Ockeysville, MD) device. T chol and triglycerides were measured with an automatic analyzer (AA II, Technicon Inst. Co.) using the enzymatic cholesterol oxidase peroxidase method. LDL was calculated as: T chol-HDL chol-1/5 trigylcerides. HDL chol was measured by the dextran sulfate Mg ²⁺ precipitation method. Antithrombin III and heparin were measured after protopath-antithrombin III and synthetic heparin substrate testing (American Dade, Miami, FL).

Results

FIGS. 4A and 4B show the treated volumes and Siebungskoeffizienten for the filtration of NHP and SCP in a temperature range of 4 to 52 ° C. Larger volumes were treated in both plasmas when the temperature was increased from 4 to 52 ° C. However, the treated volume did not increase at temperatures above 42 ° C and fell markedly at 52 ° C. The sieving of Alb increased from 4 to 42 ° C with increasing temperature and then also fell. A similar trend can be seen with fibrinogen. Significant increases in the screening of HDL chol were observed in the temperature range from 4 to 42 ° C, whereby no significant changes in LDL chol were noticed. The screening of HDL chol also fell at 52 ° C. The total distance of LDL chol and the distance ratios of HDL chol and Alb to LDL chol are shown in Table III. Maximum values of the removed amount of LDL chol and a minimal removal of HDL chol and Alb depending on the LDL chol removal were obtained at 42 ° C.

Table III:

Total distance and ratio of HDL / LDL and albumin / LDL cholesterol removal using NHP and SCP patient plasma at variable temperatures.

Conclusion: These results indicate that operating near the physiological temperature promises to prevent the heparin-induced aggregation that occurs below the physiological temperature and the prevention of filter clogging caused by these deposits when using smaller pore size membranes to separate molecules. As shown in Figures 4A and 4B, the filtration above the physiological temperature (up to 47 ° C) produces larger treated volumes and higher throughputs of albumin and HDL chol. These results show that plasma filtration near or above 37 ° C, thermofiltration, promises clinical use in the separation of plasma contaminants based on the size differences (selective separation of LDL, namely HDL sieving).

II. Ex vivo filtration

Ex vivo filtration is the continuous filtering of plasma with living organisms. The ex vivo filtration tests were carried out at 37 ° C. according to the extracorporeal circuit shown in FIG. 2.

Referring to Fig. 2, blood is drawn from the artery of a living organism in line 36 and passed to a pump 38 from which it is pumped into line 40 , passed through the pressure gauge and into the plasma separator 44 by plasma and blood cell elements be separated. The concentrated blood cell elements are conducted in line 46 , while the plasma is conducted in line 48 . From line 48 , the plasma flows through the pump 50 into line 52 and enters the water bath 54 , which is regulated by the heat controller 56 . Within the water bath 54 , the plasma flows through the heat exchanger 58 and through the pressure gauge 60 into the filter 62 , essentially holding LDL cholesterol and essentially passing HDL cholesterol, albumin and other low molecular weight macromolecules.

Plasma 62 , which is essentially free of LDL cholesterol, flows from filter 62 through line 64 and is mixed with the blood cell elements of line 46 . The mixture is then either cooled to body temperature in heat exchanger 66 or passed to line 68 where it flows through pressure gauge 70 and passed to line 72 and is returned to the vein of the living organism in a continuous process.

The following specific examples illustrate the practical application of the present invention.

Example 3

As a result of the similarity of the lipoproteins and their suitable height for a connected filtration became a hypercholesterol dog the model chosen for an ex vivo filtration. The Thyroid / Diet Dog model has become generally accepted studied extensively. Using this model were three different cholesterol ranges up evaluated at 600 mg / dl (normal, 120 mg / dl).

In two healthy male bastard dogs with one Weights of 24 to 30 kg were arteriovenous (AV) Fistulas formed. As a control, dogs with a Normal Diet (Laboratory Dog Diet 5006, Lab Chow, St. Louis,  MO) held. As a medium cholesterol concentration model became the same dog on the same diet surgical thyroid removal kept. As high The dog was using cholesterol concentration model on a special diet consisting of normal flour with 4% hydrogenated coconut oil and 0.75% cholic acid (TD 75337, Taklad, Madison, WI) after thyroid removal was added.

Under general anesthesia with nitrogen monoxide gas and nembutal injection (nembutal sodium solution, Abott Lab. IL), the ex vivo filtration studies in dogs were carried out at different cholesterol values. An AV fistula was used to enter the blood and 200 units / kg of heparin was injected as an anticoagulant. Plasma was separated into the connected extracorporeal system using a membrane plasma separator (Mitsubishi 60TW, polyethylene, Mitsubishi Rayon Co., Japan). The separated plasma was filtered using the same procedure as in the in vitro filtration (at 37 ° C), and the filtered plasma was then combined again and returned to the dog ( Fig. 3). The blood and plasma flows used were 60 and 15 ml / min, respectively. A calculated plasma volume was filtered. Ringer's solution containing 800 to 1000 ml of lactate was intravenously infused during the extracorporeal circulation.

At the same time from the arterial and plasma lines of the Filter inlets and outlets were sampled if one half and the entire volume were treated, and before and after treatment.

At 1 hour, and 1, 3, 7, 14, and 21 days after treatment, samples were taken after 14 to 16 hours of fasting. The dogs were given the same diet as before the ad libitum filtration. The biochemical measurements included cholesterol and triglyceride (automatic analyzer AA II, Technicon Instrument Co., NY), HDL cholesterol (dextran sulfate MgCl ₂ precipitation method) in addition to routine serum multiple analysis (SMA-II system, Technicon Instrument Co) and hematological Analysis (automated cell counter, Coulter Electronics Inc., FL).

The LDL cholesterol concentration of human plasma was calculated using the equation:

Total cholesterol - HDL cholesterol - 1/5 triglyceride

The LDL-VLDL cholesterol concentration in dogs was calculated as follows:

Total cholesterol - HDL cholesterol

The lipoprotein fractions for analysis were prepared by a preparatory ultracentrifuge (human LDL; 1.006 ≦ ωτ d ≦ ωτ 1.063, human HDL; 1.063 ≦ ωτ d ≦ ωτ 1.21, dog LDL-VLDL; d ≦ ωτ 1.063, dogs -HDL; 1.087 ≦ ωτ d ≦ ωτ 1.21), where d = density. Lipoprotein particle sizes were measured using sieve negative electron microscopic images. These fractions of the dog lipoproteins are not homogeneous, but are comparable to the fractions obtained by precipitation processes.

Results

Table IV shows the cholesterol concentration at various stages in the dog model. Total cholesterol, particularly LDL-VLDL cholesterol, was increased and the ratio of LDL-VLDL cholesterol to HDL cholesterol was increased more than ten times. Albumin showed no noticeable change. Connected plasma filtration was performed at each cholesterol level. The transmembrane pressure ( P _tm ) of the plasma separator was stable throughout the procedure. The sieving coefficients of albumin and total cholesterol and other macromolecules were greater than 95%. The P _tm value of the macromolecular filter increased gradually during the flow. The P _tm values for a treated plasma volume ranged from 10 to 256 mmHg (13.3 to 329.5 mbar). Notable differences in the changes in P _tm did not depend on the cholesterol concentrations.

Table IV

Cholesterol and Albumin Levels in a Dog Hypercholesterolemia Model

Table V shows the mean sieving coefficients with different cholesterol values. LDL-VLDL cholesterol was strongly retained by the plasma filter, whereas albumin and HDL cholesterol showed high screening. The sc value of the LDL-VLDL cholesterol decreased with increased cholesterol.

Table V

Average screening coefficients of the macromolecule filter, combined ex vivo filtration test (37 ° C) of Kuraray Eval 4A with different cholesterol values

Fig. 5 shows the particle size distribution of the lipoprotein FHC for the plasma and the dog plasmas with different levels of cholesterol. The size difference between the HDL and the LDL of the FHC plasma was larger than that of the dog plasmas. The particle diameter and the deviation from LDL-VLDL in the dog plasmas were also increased, but not to such an extent as in human plasma. The HDL size was not significantly different between these groups.

Fig. 5 shows the post-treatment recovery of HDL and VLDL cholesterols HCL. Recovery of LDL-VLDL cholesterol was prolonged in the higher cholesterol groups. Groups II and III took approximately two weeks to return to pre-treatment values. HDL cholesterol recovery was constant and returned to pre-treatment values for all groups within 7 days. Fig. 6 shows the changes in the LDL-VLDL-cholesterol / HDL-cholesterol ratios. This ratio decreased during the post-filtration period and was kept at a lower value for 14 days. The tendency to a more reduced ratio for longer periods compared to the values before or after treatment was greater in group III, which had the most cholesterol.

Conclusion:

These data show that the particle size of the lipoprotein and the screening coefficients very much from the cholesterol concentration depend. As well as the cholesterol concentration increases, the particle size increases of lipoprotein (especially LDL / VLDL) the screening and the total distance increases of cholesterol (LDL-VLDL-cholesterol).

A comparison of the sieving coefficients shows that the LDL-VLDL screening in dogs larger than that in human LDL is. This relationship is established by examining the Particle size explains the larger deviations and Overlaps between LDL-VLDL and HDL in dogs shows which makes it more difficult to get lipoproteins in dogs separate than in humans. These results show that thermofiltration in humans in relation to the selective Lipoprotein removal quite effective  is.

Furthermore, this data shows that there is a further continuous recovery of LDL-VLDL cholesterol in the more hypercholesterolemic levels while HDL cholesterol recovery remains relatively normal. Reducing LDL Cholesterol With Obtaining HDL cholesterol through thermofiltration and the ongoing Recovery of LDL-VLDL cholesterol with retention of the lower LDL / HDL ratio is one important indication of an effective method of treatment of lipoprotein abnormalities.

Example IV

Initially, clinical thermofiltration procedures were used a secondary hypercholesterolemia patient. The patient selected for the trial was a 39 year old man who has a high concentration (210 to 450 mg / dl) cholesterol and a very high LDL / HDL Cholesterol ratio (8-30) due to cholestasis Sclerosis cholangitis.

According to the connected system shown in Fig. 2, the thermal filtration tests were carried out. The blood flow was set at 100 ml / min and the plasma flow at 30 ml / min. Toray PS-05 (Toray Industries, Tokyo, Japan) and Asahi Plsamaflol (AP 0511: Asahi Medical Co., Tokyo, Japan) modules were used as plasma separators, and Eval 4A 2.0 m ² (Kuraray Co., Osaka, Japan) were used as plasma filters. The filter and hot plate were fitted with an electrical heating pad to maintain the temperature in the cold chamber at 37 ° C in the Cryomax device (Cryomax 360; Parker Biomedical, Irvine, CA, USA). To prevent coagulation, 5000 units of heparin were injected as a bolus before the extracorporeal circuit was initiated. The treated plasma volume and transmembrane pressure were continuously monitored during the procedure. Filtration was carried out until the transmembrane pressure ( P _tm ) of the plasma filter reached 500 mm Hg (665 mbar). Samples were taken from the filter's plasma inlet and outlet lines simultaneously when the P _{tm reached} 150 and 300 mm Hg (199 to 399 mbar) to calculate the screening coefficients ( sc ).

The solute sieve was calculated as the concentration in the filtrate divided by the concentration in the plasma inlet to the plasma filter. The biochemical measurements included cholesterol and triglyceride (AAII automatic analyzer, Technicon Instrument Co., Tarrytown, NY, USA) and HDL cholesterol (dextran sulfate-MgCl ₂ precipitation method) in addition to routine serum multiple analysis (SMA-II, Technicon Instrument Co.). After plugging, the filter was removed from the circuit and the plasmapheresis procedure changed to plasma exchange using a 5% albumin solution as the substitution fluid.

The plasma exchange continued until a calculated one Plasma volume (2893 ml) by plasma exchange alone was treated.

The in vitro filtration studies were under Using the same filter, the same temperature and plasma from the same patient as in Example 1 described.  

Results

This procedure was well tolerated by the patient and no backlash was observed. No substitution fluid was used during the thermofiltration phase. Up to a P _tm of 500 mm Hg (665 mbar), 1355 ± 275 ml (1160 and 1540 ml) of the plasma were filtered, and 1117 ± 183 ml (980 and 1253 ml) were up to a P _tm of 300 mm Hg (399 mbar) filtered. The course of the P _tm value as a function of the filtered volume was comparable to the in vitro investigations with the plasma of this patient, as was the filtered volume (1060 ml treated up to 300 mm Hg (399 mbar) of the P _tm value in vitro).

There was almost complete retention of LDL + VLDL cholesterol ( sc = 0.02) and high throughput of albumin ( sc = 0.75 and HDL cholesterol ( sc = 0.78). Fibrinogen screening was low (0, 07) These results were comparable to the in vitro filtration results (Table VI below).

Table VI

Concentration and sieving coefficient ( sc ) of the solute (mean ± SD)

Conclusions

The sieving coefficients of LDL cholesterol (0.02), Demonstrate HDL cholesterol (0.78) and albumin (0.75) the selectivity of thermofiltration. These results are using the in vitro filtration tests comparable to the plasma of the same patient. The advantage of this system compared to the plasma exchange, is the maintenance of the HDL (antiatherogenes Lipoprotein) and other essential plasma admixtures, that would be excreted during plasma exchange. The Thermofiltration is more selective than membrane schemes without Temperature control and easier to use because of it no other plasma treatment steps or addition potentially harmful chemical additives. In addition, abnormal concentrations can vary Proteins (such as immunoglobulins) through thermofiltration can also be removed effectively.

Claims (3)

1. Device for the more selective removal of macromolecules from a plasma solution, characterized by :

• a) a device for dividing a plasma-containing solution which contains macromolecules into a concentrated cell element stream and a plasma stream,
• b) a device for heating the plasma flow to a temperature above normal body temperature, but below its boiling point,
• c) means for filtering the heated plasma stream to selectively remove the macromolecules;
• d) means for receiving the filtered plasma stream and the concentrated cell element stream, and connecting these streams to form a treated stream that is substantially free of selective macromolecules.

2. Device according to claim 1, characterized in that they continue to have a device for cooling the combined current to normal body temperature and for returning the fluid to the samples. 3. Device according to claim 1, characterized in that that the heating device is adapted to the plasma flow to a temperature in the range of to heat about 35 to about 60 ° C.