Transmembranous Transport and Adsorption of Beta-2-microglobulin during Hemodialysis using Polysulfone, polyacrylonitrile, polymethylmethacrylate and Cuprammonium Rayon Membranes

Beta-2-microglobulin (b2M) was identified as a causative agent of amyloidosis associated with long-term hemodialysis (HD). Therefore, we examined handling of b2M during a 4-hour hemodialysis session. We compared b2M adsoprtion and diffusive/convective elimination between high-flux membranes such as polysulfone (PS; F 60®, Fresenius), polyacrylonitrile (AN 69; FiltralR, Hospal) and polyacrylonitrile (PAN, PAN 12CX2R, Asahi) and less permeable membranes such as cuprammonium rayon (CR; AM 160 HR, Asahi) and polymethylmethacrylate (PMMA; BK-1.6 UR, Toray). To calculate total elimination, arterio-venous differences of b2M were measured at 0, 5, 20, 60 and 240 minutes; dialysate concentration was analyzed to evaluate diffusive/convective transport. Differences between recovery in dialysate and total removal were regarded as amount removed by adsorption. Total elimination per 4-hour hemodialysis session and per m2 membrane surface was 154.7 ± 12.3 mg for the PS, 137.8 ± 28.4 mg for the AN 69, 179.8 ± 47.5 mg for the PAN, 130.8 ± 11.8 mg for the PMMA and 14.4 ± 16.0 mg for the CR membrane. Diffusive/convective transport was 128.0 ± 18.1 mg for PS, 54.7 ± 8.1 mg for AN 69 and 106.5 ± 20.8 mg for PAN and insignificant for PMMA and CR. Adsorption was 26.7 ± 4.3 mg for PS, 83.1 ± 29.0 mg for AN 69 and 59.8 ± 17.2 mg for PAN. Besides transmembranous transport sorption is an important mode of elimination. Weekly endogenous generation rate is about twice as high as b2M elimination

Beta-2-Microglobulin Adsorption and Release in-Vitro: Influence of Membrane Material, Osmolality and Heparin

We studied the effects of cuprammonium rayon (CR), polyacrylonitrile (PAN), polysulfone (PS), changes in osmolality, and heparin dosage on beta-2-microglobulin (b2M) handling in an in-vitro model that excluded convective transport and minimized diffusive transport. Both PAN and PS exhibited high adsorption capacity for b2M. Osmolality changes had no effect on b2M adsorption or release. CR membrane adsorption was minimal but increased slightly when higher heparin doses were used. In experiments with CR and high heparin doses (4 U/ml) b2M release occurred during the first 15 minutes of in-vitro dialysis, but this increase was inhibited by removing the leukocytes from the blood, indicating that b2M is released from leukocytes.

In vitro-Untersudiungen über Angriffspunkt und Wirkungsunterschiede zum Heparin / In Vitro Studies on the Mode of Action and Differences to Heparin

The effect of a semisynthetic pentosan-polysulfo-ester (SP 54) upon the complement system in vitro has been studied in comparison with the effects of heparin. Both substances inhibit in small concentrations the Cl-esterase. There are differences in the effect of SP 54 and heparin. According to the in vitro results SP 54 seems to have a ten times higher anticomplementary action. At the same time the influence upon coagulation is less. SP 54 appears to be a substance of therapeutic interest.

Prevalence of adrenal and extra-adrenal Conn syndrome in hypertensive patients

BACKGROUND

Primary aldosteronism (PA) is caused by an adrenal aldosterone-producing tumor (A-APT) or adrenal hyperplasia. An extra-adrenal APT (E-APT) as a cause of PA has been reported in 5 cases. Autopsy studies show a high incidence of ectopic adrenocortical tissue. We did a prospective study of the prevalence of A-APTs and E-APTs and the biochemical features of E-APTs in patients with PA.

METHODS

Hypertensive patients (N = 3900) referred to our unit were screened for PA by measuring renin activity, urinary aldosterone-18-glucuronide, tetrahydroaldosterone, and 18-hydroxycorticosterone (18-OH-B). Primary aldosteronism was found in 257 cases. The differentiation between A-APTs and adrenal hyperplasia was based on the results of postural response of renin, plasma aldosterone, 18-OH-B, computed tomography, isotope scanning, or adrenal venous aldosterone. Ultrasound examination of the abdomen was used to screen for E-APT.

RESULTS

The cause of PA was bilateral adrenal hyperplasia in 101 cases, unilateral adrenal hyperplasia in 2, an A-APT in 146, and an E-APT in 1. The site of aldosterone production was uncertain in 7 patients who had normal adrenal glands on computed tomography but refused to undergo isotopic scanning and adrenal venous catheterization. Ultrasound examination disclosed normal retroperitoneum in 4 of the 7 cases but could not rule out E-APT in 3 cases. The biochemical features of the patient with the E-APT were similar to classic A-APT, with low renin, high aldosterone, and high 18-OH-B values without appropriate response to posture or to short-term volume expansion. The excision of the E-APT in the right kidney resulted in normalization of blood pressure and renin, aldosterone, and 18-OH-B levels.

CONCLUSION

Although E-APT is rare, it should be considered in the interests of specific therapy for PA because aldosterone-secreting malignant ovarian tumors also have been reported.

Role of 21-deoxyaldosterone in human hypertension

21-Deoxyaldosterone has been postulated to be a precursor of aldosterone in an alternative biosynthesis pathway and Kelly's-M1 is considered to be its metabolite. In healthy volunteers, the excretion rate of 21-deoxyaldosterone and of Kelly's-M1 are significantly lower than the aldosterone metabolites, aldosterone-18-glucuronide and tetrahydro-aldosterone and than the aldosterone precursor 18-OH-corticosterone. Essential hypertension patients (with low and normal renin) excrete comparable values of 21-deoxyaldosterone and Kelly's-M1 as normotensives. In 66% of aldosterone-producing adenoma cases (APA) and in 60% of idiopathic hyperaldosteronism (IHA) patients, significantly raised values of 21-deoxyaldosterone and Kelly's-M1 were found. The patients with the high excretion rates of both steroids showed only moderately increased values of the aldosterone metabolites, aldosterone-18-glucuronide and tetrahydro-aldosterone, as well as of the aldosterone precursor 18-OH-corticosterone. In contrast, the latter mentioned steroids were excreted in higher amounts in those patients with normal excretion of 21-deoxyaldosterone and Kelly's-M1. Hence, it is suggested that aldosterone is produced alternatively either via 18-OH-corticosterone alone or additionally via 21-deoxyaldosterone. Furthermore, in three cases of "incidentally" discovered adrenal adenomas, 21-deoxyaldosterone and Kelly's-M1 were the only elevated steroids. After adrenalectomy, excretion of 21-deoxyaldosterone and of Kelly's-M1 and blood pressure returned to normal, which proves that these steroids play a role in blood pressure regulation. In essential hypertension, ACTH infusion induced a significant increase of 21-deoxyaldosterone and Kelly's-M1. However, the increase after angiotensin II was 3- to 6-fold higher than after ACTH. IHA patients proved to be more responsive to angiotensin II; and, in contrast, APA cases proved to be more sensitive to ACTH. The data suggest that beside the main route of aldosterone biosynthesis via 11-deoxycorticosterone, corticosterone and 18-OH-corticosterone an alternative pathway exists via 21-deoxyaldosterone in healthy and in hypertensive patients. There are similarities between the regulation of 21-deoxyaldosterone and the regulation of aldosterone. The determination of 21-deoxyaldosterone and its possible metabolite Kelly's-M1 might be appropriate in the diagnosis of mineralocorticoid-induced forms of hypertension, especially when an adrenal adenoma is discovered.

Characterization of "refilling types" by continuous blood volume monitoring during hemodialysis

Fluid removal during HD is frequently associated with acute hypotension due to insufficient mobilization of extravascular fluid and subsequent hypovolemia. Large variability in vascular refilling makes dialysis therapy difficult and requires a better understanding of fluid distribution in the individual hemodialysis (HD) patient. Blood volume monitoring was performed by continuous measurement of blood density with a DMA 46 Density Meter (Fa. Chempro, PAAR, Austria) in six patients on regular HD treatment. A body filtration coefficient (CF = extra/intravascular fluid shift) was calculated using a computer model by Schneditz et al (1990) and blood density was measured during a 60-minute ultrafiltration period (1/3 x delta kg/hr = 19 +/- 4 ml/min). Concerning blood density differences (delta f%) and body filtration coefficient (CF) there was a wide inter-individual range (delta f = 2.8-8.0%, CF = 3-9 ml/mm Hg/min), but there was a good intraindividual reproducibility of delta f and CF. A negative correlation (r = -0.95) between delta f and CF could be established. The severity of hypotensive episodes and frequency of interventions correlated well with delta f and CF; severe symptoms occurred with a delta f > 6% and a CF < 4 ml/mm Hg/min. These results suggest that improvement in dialysis therapy can be achieved by blood volume monitoring and classification of "refilling types." By blood volume-controlled computerized sodium and UF profiles, a reduction of hypotensive episodes and emergency intervention might be possible.

Transmembranous transport and adsorption of beta-2-microglobulin during hemodialysis using polysulfone, polyacrylonitrile, polymethylmethacrylate and cuprammonium rayon membranes

Beta-2-microglobulin (b2M) was identified as a causative agent of amyloidosis associated with long-term hemodialysis (HD). Therefore, we examined handling of b2M during a 4-hour hemodialysis session. We compared b2M adsoprtion and diffusive/convective elimination between high-flux membranes such as polysulfone (PS; F 60, Fresenius), polyacrylonitrile (AN 69; Filtral, Hospal) and polyacrylonitrile (PAN, PAN 12CX2, Asahi) and less permeable membranes such as cuprammonium rayon (CR; AM 160 H, Asahi) and polymethylmethacrylate (PMMA; BK-1.6 U, Toray). To calculate total elimination, arterio-venous differences of b2M were measured at 0, 5, 20, 60 and 240 minutes; dialysate concentration was analyzed to evaluate diffusive/convective transport. Differences between recovery in dialysate and total removal were regarded as amount removed by adsorption. Total elimination per 4-hour hemodialysis session and per m2 membrane surface was 154.7 +/- 12.3 mg for the PS, 137.8 +/- 28.4 mg for the AN 69, 179.8 +/- 47.5 mg for the PAN, 130.8 +/- 11.8 mg for the PMMA and 14.4 +/- 16.0 mg for the CR membrane. Diffusive/convective transport was 128.0 +/- 18.1 mg for PS, 54.7 +/- 8.1 mg for AN 69 and 106.5 +/- 20.8 mg for PAN and insignificant for PMMA and CR. Adsorption was 26.7 +/- 4.3 mg for PS, 83.1 +/- 29.0 mg for AN 69 and 59.8 +/- 17.2 mg for PAN. Besides transmembranous transport sorption is an important mode of elimination. Weekly endogenous generation rate is about twice as high as b2M elimination.

Inappropriate secretion of antidiuretic hormone, polydipsia and hypothalamic calcifications

We studied a 41 year old patient who had pathologic fluid intake of 10 1/day together with syndrome of inappropriate antidiuretic hormone. Imaging studies revealed a lesion of the anterior wall of the third cerebral ventricle. A review of relevant literature indicated several different disturbances by which alterations of thirst, vasopressin-secretion and abnormalities of anterior third ventricle may be associated. The present case presents an unusual and potentially dangerous combination in this spectrum of changes.

Beta-2-microglobulin adsorption and release in-vitro: influence of membrane material, osmolality and heparin

We studied the effects of cuprammonium rayon (CR), polyacrylonitrile (PAN), polysulfone (PS), changes in osmolality, and heparin dosage on beta-2-microglobulin (b2M) handling in an in-vitro model that excluded convective transport and minimized diffusive transport. Both PAN and PS exhibited high adsorption capacity for b2M. Osmolality changes had no effect on b2M adsorption or release. CR membrane adsorption was minimal but increased slightly when higher heparin doses were used. In experiments with CR and high heparin doses (4 U/ml) b2M release occurred during the first 15 minutes of in-vitro dialysis, but this increase was inhibited by removing the leukocytes from the blood, indicating that b2M is released from leukocytes.

[Hypokalemia as the principal symptom of covert vomiting. Clinical and diagnostic aspects]

In ten adults (nine females), referred for hypokalemia as the cardinal symptom of uncertain etiology and normal blood pressure, surreptitious self-induced vomiting was demonstrated as the main cause. In the majority of such patients, the pathognomonic pattern of serum and urine electrolytes (in the unstable phase--loss of gastric juice) allows diagnosis without hospitalization. If there are atypical urinary electrolyte values or the patients deny vomiting, hospitalization or part-hospitalization is recommended, with parenteral administration of 1 litre physiological saline daily under weight control, and (if necessary) toxicological urine tests for diuretics if there is a high urinary chloride level. In this manner a sufficiently accurate diagnosis is possible.

Permeability and secondary membrane formation of a high flux polysulfone hemofilter

It has been assumed that the molecular weight (MW) cut-off of a newly fabricated polysulfone capillary dialyzer (F60, Fresenius, FRG) is similar to that of the human glomerulus. We recently tested the device in vivo and found this not to be so, based on the device's ability to eliminate substances of a MW of 10,000 to 60,000 daltons. One of the reasons for this discrepancy was found to be the influence of secondary membrane formation on solute permeability. Endogenous marker substances of a defined MW (beta 2-microglobulin, myoglobin, RBP, alpha 1-microglobulin, acid alpha 1-glycoprotein, alpha 1-antitrypsin, prealbumin, and albumin were measured by laser nephelometry or radioimmune assay; sieving coefficients (SC) and protein eliminations were calculated for each low MW protein.

Three cases of hemodialysis-associated hypersensitivity reactions

According to the United States Food and Drug Administration, untoward reactions to capillary hemodialyzers occur at a rate of 3.5 of every 100,000 dialyzers sold. Allergic symptoms immediately after initiation of dialysis consist of burning retrosternal pain, sensation of diffuse heat, cold perspiration, periorbital and facial edema, flushing, laryngeal stridor, bronchial hypersecretion, hypotension, bradycardia, and loss of consciousness. In 1982 Popli et al. reported four patients suffering from such allergic manifestations; three were successfully managed after being taken off dialysis. These investigators thought that inadequate rinsing of cuprammonium cellulose capillary dialyzers was responsible for the reactions, and recommended rinsing the blood compartment with 2 liters of normal saline, and the dialysate compartment with 10 liters of dialysate, both in a single-pass fashion over 20 minutes. Nichols and Platts (1982) (3) reported 15 patients with urticaria, severe bronchospasm, and shock occurring immediately after the blood had been returned from the dialyzer. These authors suggested that the sterilizing agent, ethylene oxide (ETO), was responsible. Poothullil et al. (1975) (4) described a patient with pruritus, severe dyspnea, and hypotension during dialysis. On the basis of a positive skin prick test (dermal reaction to ETO-exposed human albumin) and of antigen-induced histamine release from peripheral leucocytes, these workers suggested that ETO was responsible for the allergic reactions. Marshall et al. (1984) (5) reported that 8.9% of hemodialysis patients had positive skin tests to ETO and that 12.1% were ETO-radioallergosorbent test (RAST) positive.(ABSTRACT TRUNCATED AT 250 WORDS)

[Quantitative determination of total urinary protein utilizing the principle of Coomassie Brilliant Blue G250 binding to protein (author's transl)]

Coomassie Brilliant Blue G250 was used for the determination of total urinary protein and compared with the biuret-procedure. In the Coomassie Brilliant Blue G250-assay 0.10 ml urine are added to 5.0 ml Coomassie Brilliant Blue G250 reagent and the sample is read against the reagent blank. The Coomassie Brilliant Blue G250 method seems to be superior to the biuret-procedure because of better reproducibility, higher sensitivity and simpler handling. The upper limit or urinary protein excretion in 49 healthy subjects was 120 mg/24 h. To evaluate the clinical significance of the Coomassie Brilliant Blue G250 method the urinary protein concentration of 134 patients with metabolic, systemic and organ diseases was compared with the biuret-procedure. The regression line was y = 0.827 X + 8.713 mg/l with a correlation coefficient of r = 0.966. The type of proteinuria (mixed, glomerular, tubular) had no influence on the protein value measured with the Coomassie Brilliant Blue G250 method. However in selective proteinuria, like Bence-Jones protein excretion, there is no correlation between the two methods, because the concentration of Bence-Jones protein is underestimated. Lower protein values were also frequently obtained for patients with diabetes mellitus. Some specimens from patients with chronic renal failure treated by haemodialysis showed elevated values. In spite of these limitations the Coomassie Brilliant Blue G250 method might become the method of choice for the determination of total urinary protein.

[Fanconi syndrome in an adult coincident with early myeloma with monoclonal IgG, type kappa, anomaly (author's transl)]

First description of a case of early myeloma with monoclonal IgG, type kappa, anomaly plus Bence-Jones proteinuria and Fanconi's syndrome in a 67-year-old woman. Characteristic crystalline inclusion bodies were found in plasma cells of bone marrow and renal tissue.

Dissociation in the excretion of different aldosterone metabolites and unmetabolized ('free') aldosterone in hypertension

1. The determination of aldosterone-18-glucuronide (pH 1-labile aldosterone) was complemented by concomitant measurements of free urinary aldosterone and tetrahydroaldosterone in 307 patients, most of whom were hypertensive. In 38 cases (12.3%) the normal, aldosterone-18-glucuronide concentration was clinically misleading, but increased free aldosterone and/or tetrahydroaldosterone values suggested the presence of hyperaldosteronism, which in many of these cases was confirmed by elevated excretion of the possible major aldosterone precursor 18-hydroxycorticosterone (18-OH-B). 2. Of 224 patients with essential hypertension and normal or low plasma renin activity 18 had an elevated free aldosterone and/or tetrahydroaldosterone excretion without increased aldosterone-18-glucuronide. These cases may represent early or pre-symptomatic forms of primary hyperaldosteronism. In other cases, particularly when tetrahydroaldosterone was increased alone, abnormalities of aldosterone metabolism were suspected. 3. In two out of 15 patients with primary hyperaldosteronism, aldosterone-18-glucuronide values were frequently found to be normal, although elevations were noted in other variables. However, no relation to the morphological abnormality (adenoma versus hyperplasia) was seen.

[Idiopathic edema, capillaropathy, pericardial and pleural effusions with high protein content (author's transl)]

Clinical and electron microscopic studies of two female patients are reported who, in addition to the symptoms and signs of idiopathic edema, had pericardial (and pleural) effusions. In one patient pericardiectomy had to be performed, in the other patient pharmacotherapy with spironolactone was effective. In these patients the protein-concentrations of edema fluid (25 and 12 g/l) and pericardial fluid (55-61 and 48 g/l) were relatively high; the distribution space of labelled protein was increased; blood volumes were low-normal or decreased. Electronmicroscopy of the microvasculature showed identical alterations in both cases. In the cutaneous vessels the endothelium developed numerous abnormal cytoplasmic processes and intercellular "gaps". In the capillaries of skeletal muscle our findings indicate an increase in vesicular transport. We suggest the electron microscopic alterations to be the morphologic correlate for the increased transport and extravascular accumulation of protein. Changes as they are described here in humans with idiopathic edema have been documented before in animals with experimental edema.