On line filtration of dialysate: structural and functional features of an asymmetric polysulfone hollow fiber ultrafilter (Diaclean®)

The endotoxin transfer across dialysis membranes has been investigated using specific in vitro circuits. Backdiffusion and backfiltration have been analyzed and most dialysis membranes have shown to be permeable to LAL positive substances. Synthetic membranes however display the better capacity of retention of these products despite their higher porosity and permeability. For such reason synthetic polysulfone ultrafilters are used as pyrogen filters to obtain ultrapure dialysate. We have investigated the characteristics of a polysulfone ultrafilter named Diaclean and manufactured by Amicon Ireland. The capacity of endotoxin retention has been investigated both in filtration and backfiltration modes on new and used ultrafilters. The capacity of endotoxin adsorption was investigated as well. Used ultrafilters appeared to maintain the retention capacity and the adsorption capacity up to 4 months of use. Only slight differences were noted from the baseline values (p = n.s.). The best adsorption capacity is always displayed by the outer layer of the membrane suggesting its best utilization in back filtration mode with tangential flow. No morphological changes were observed in the used membrane analyzed by scanning electron microscopy.

Leaching and Corrosion of Polyvinyl Chloride (PVC) Tubes in a Dialysis Water Distribution System

PVC tubes, from the dialysis water distribution system of a 14 and a 7 year old plant, were analysed by scanner electron microscopy (SEM) and X-ray microanalysis (EDAX). Results showed that the leaching of material occurs depending on time of use. The phenomenon does not modify the chemical composition of the material. Results suggest that PVC alterations, induced by time, could support bacterial proliferation thus reducing the quality of dialysate.

Assessment of occlusion of the vascular access in patients on chronic hemodialysis: comparison of physical examination with continuous-wave Doppler ultrasound. STOP Investigators. Shunt Thrombotic Occlusion Prevention with Picotamide

BACKGROUND

Dialysis access occlusion is the most common cause of hospitalization and a frequent indirect cause of mortality in patients on chronic hemodialysis. The clinical assessment of an arteriovenous shunt is presently the most widely adopted method for the diagnosis of vascular access occlusion in hemodialysis patients, but no studies have yet investigated objectively its sensitivity and positive predictive value (PPV). Continuous-wave (CW) Doppler ultrasound is a simple, inexpensive, and noninvasive technique for the assessment of arterial blood flow. We have carried out a prospective evaluation of the PPV of CW Doppler for the diagnosis of vascular access occlusion in hemodialysis patients and compared it with clinical investigation.

METHODS

Fourty-one hemodialysis patients with clinical diagnosis of occlusion of their fistula were studied, and in 23 of them the diagnosis of occlusion was objectively validated.

RESULTS

CW Doppler in the patients in whom occlusion was objectively validated showed PPV of 86 and 83% under basal conditions and after fistula compression, respectively, with sensitivities of 95 and 100%, respectively. Clinical diagnosis, under the same conditions, showed a PPV of 83% and a sensitivity of 100%.

CONCLUSIONS

CW Doppler and clinical examination have a similar high sensitivity for the diagnosis of occlusion of the dialysis access; thus, there is no need to use routinely Doppler CW examination, unless objective documentation is required.

Which level of cytokine production is critical in haemodialysis?

Monocyte activation with cytokine production is a well known event in the course of dialysis treatment but its relation to symptoms of haemodialysis or long-term pathological changes in chronic dialysis patients is still under discussion. Cytokine production depends on the balance between inducers and inhibitors while effects rely on the peculiar uraemic environment and cell metabolism. 'Foot-prints' for monocyte activation have been found, but no marker for clinical symptoms has been demonstrated clearly. In this scenario it is almost impossible to link a specific symptom to a definite stimulus such as dialysate microbial contamination or membrane complement generation. The topics discussed in this paper include cytokines synthesis modulation factors, levels in haemodialysis patients, and results of finding markers of clinical relevance. Special attention is paid to microbial contamination of dialysis fluid with analysis of cytokine inducing substances in commercial sterile solutions. Data on cytokine synthesis and activity in the aged are also discussed, with special regard to the haemodialysis setting.

Acute renal failure of medical type in an elderly population

One hundred and nine unselected patients with Acute Renal Failure (ARF) of medical aetiology were hospitalized at the Nephrological Unit of Policlinico University Hospital (Modena) during a 30-month period. ARF was considered as a rapid increase of serum creatinine > 2mg/dl over the baseline level or the doubling of pre-existing value in chronic renal failure. Mean age of patients was 67+/-17 years and median age was 72; 64.2% needing dialytic treatment. Four main causes of ARF were identified: 33 patients had reduced renal perfusion by dehydration, hypotension etc.; 20 multifactorial aetiology; 14 biopsy-investigated renal parenchymal diseases and 39 had drug-related acute renal failure (D-ARF). The clinical outcome was significantly worse in elderly patients as regard mortality (P < 0.02), chronic dialytic treatment (P < 0.04) and complete recovery (P < 0.004). The mean age of D-ARF patients was significantly greater than remaining ARF patients (72.6+/-12.8 vs 63.2+/-18.5: P < 0.004. Nonsteroidal antiinflammatory drugs (NSAIDs) and ACE-inhibitors (Ace-i) caused ARF in 24 and 8 patients respectively. Elderly age, vascular disease and monoclonal gammopathy represented the main risk factors and were significantly more frequent in D-ARF patients (P<001, <0.01, <0.04 respectively). Our data confirm the high susceptibility of ageing kidneys to nephrotoxic damage caused by drugs affecting glomerular autoregulation by microvascular mechanisms. Greater attention to renal changes in ageing and an increased dissemination of preventative measures among nephrologists, could reduce the incidence of these serious and potentially lethal diseases.

Natural history of nutrition in chronic renal failure

Dietetic manipulation significantly influences the progression of renal failure in laboratory animals. Clinical results in humans are contradictory. The aim of the study was epidemiological research on a large sample of kidney disease patients to verify whether renal failure influences nutrient intake before dietetic manipulation. Four hundred and forty-one consecutive, non-selected adult patients with renal insufficiency (creatinine 133-963 mumol, mean 301 +/- 178 mumol in male, 288 +/- 156 mumol/l in female) and 43 kidney disease patients without renal failure were enrolled in the prospective study in the period 1988-1995. Interview at the time of the first nephrological check was performed by only one dietician; the record by recall of intake over 7 days with quantitative assessment was collected with the assistance of nutritional dossier and photographic measures. The patients with renal failure consume energy, proteins, lipids and carbohydrates in lesser quantities than the national population of the same geographical area, but the total lipid and monounsaturated fatty acid intake is higher compared with Italian dietary reference values. In patients with renal failure mean protein intake was 1.02 +/- 0.2 g/kg/day in males and 0.96 +/- 0.2 g/kg/day in females; mean lipid intake was 1.10 +/- 0.2 g/kg/day in males and 1.17 +/- 0.3 g/kg/day in females; mean carbohydrate intake was 3.7 +/- 1.1 g/kg/day in males and 3.49 +/- 1 g/kg/day in females. The nutrition alterations observed in chronic renal failure may be a biological adaptation due to neurological changes affecting the sense of taste.

Haemodialysis therapy in the elderly

Haemodialysis therapy in the elderly has become a recognized reality only in the last decade Information collected from restricted statistics often leads to conflicting conclusions. Length of survival may be a useful indicator of the appropriateness of initiating treatment. Survival and important determinants of survival, such as cardiovascular problems, nutritional status and adequacy of dialysis, are addressed in this study and evaluated in 365 elderly patients, treated at a single institution over a 20 year period.

No direct evidence of increased lipid peroxidation in hemodialysis patients

Lipid peroxidation, as measured by the thiobarbituric acid test, has been reported to have increased in hemodialysis (HD) patients, even though the test has low specificity in vivo. Conjugated diene fatty acid (CDFA) hydroperoxides are formed during lipid peroxidation, but not all conjugated dienes (CD) detected in humans originate from lipid peroxidation: octadeca-9,11-dienoic acid, a nonhydroperoxide CD derivative of linoleic acid (CDLA), has a dietary origin. We evaluated CDFA hydroperoxides, CDLA and linoleic acid, using high-performance liquid chromatography, in lipids extracted from plasma, adipose tissue and RBC membranes obtained from 25 patients treated with HD, 16 patients treated with hemodiafiltration (HDF) and 29 controls. No differences in the levels of CDFA hydroperoxides and linoleic acid were seen in any of the groups. Concentrations of CDLA were found to be significantly high in the adipose tissue and low in the RBC membranes of HD patients. HDF-treated patients showed the same results as HD patients. No direct evidence of increased lipid peroxidation was found in HD patients. This does not exclude the possibility that lipid peroxidation is increased and escapes direct detection due to the body's homeostatic control eliminating the increased production of hydroperoxides. Both HD- and HDF-treated patients showed a significant change in CDLA concentrations, either in the adipose tissue, or in the RBC membranes. These dietary CD may be mistaken for markers of lipid peroxidation by conventional methodologies.

Leaching and corrosion of polyvinyl chloride (PVC) tubes in a dialysis water distribution system

PVC tubes, from the dialysis water distribution system of a 14 and a 7 year old plant, were analysed by scanner electron microscopy (SEM) and X-ray microanalysis (EDAX). Results showed that the leaching of material occurs depending on time of use. The phenomenon does not modify the chemical composition of the material. Results suggest that PVC alterations, induced by time, could support bacterial proliferation thus reducing the quality of dialysate.

On line filtration of dialysate: structural and functional features of an asymmetric polysulfone hollow fiber ultrafilter (Diaclean)

The endotoxin transfer across dialysis membranes has been investigated using specific in vitro circuits. Backdiffusion and backfiltration have been analyzed and most dialysis membranes have shown to be permeable to LAL positive substances. Synthetic membranes however display the better capacity of retention of these products despite their higher porosity and permeability. For such reason synthetic polysulfone ultrafilters are used as pyrogen filters to obtain ultrapure dialysate. We have investigated the characteristics of a polysulfone ultrafilter named Diaclean and manufactured by Amicon Ireland. The capacity of endotoxin retention has been investigated both in filtration and backfiltration modes on new and used ultrafilters. The capacity of endotoxin adsorption was investigated as well. Used ultrafilters appeared to maintain the retention capacity and the adsorption capacity up to 4 months of use. Only slight differences were noted from the baseline values (p = n.s.). The best adsorption capacity is always displayed by the outer layer of the membrane suggesting its best utilization in back filtration mode with tangential flow. No morphological changes were observed in the used membrane analyzed by scanning electron microscopy.

Beta-1 integrins in the normal human glomerular capillary wall: an immunoelectron microscopy study

The localization of the alpha 2, alpha 3 and alpha 6 subunits of the beta 1 integrin family on different cells of the glomerular capillary wall and on juxta-capillary mesangium was investigated using an immunoelectron microscopic technique on freshly harvested normal human glomeruli. Alpha 2 beta 1, alpha 3 beta 1 and alpha 6 beta 1 were weakly expressed on both luminal and abluminal surfaces of glomerular endothelial cells; alpha 2 beta 1 and alpha 3 beta 1 were also found on the mesangium of the juxta-capillary areas. Alpha 3 beta 1 was regularly present in great density on the basal and lateral surface of podocyte foot processes, confirming alpha 3 beta 1 as the unique beta 1 integrin on glomerular epithelial cells. None of these integrins was strictly polarized along the glomerular basement membrane, thus suggesting, in agreement with recent literature, that these molecules perform other biological functions in addition to adhesivity.

Ultrafiltration and endotoxin removal from dialysis fluids

Biocompatibility in hemodialysis is now regarded as a multifactorial problem and dialysate represents a main risk. Pyrogenic fractions mostly coming from gram-negative bacteria easily pass through dialysis membrane, either by backdiffusion or by backfiltration, and induce blood cell activation. To demonstrate the long-term efficiency of a 2 m2 polyamide ultrafilter in producing a pyrogen free solution, we used an experimental circuit ultrafiltering for 240 hours (500 ml/min) a bicarbonate dialysate contaminated (5 to 48 EU/ml) by a Pseudomonas aeruginosa filtrate. The efficiency was monitored by LAL-test and IL-1 PBMC so to detect not only lipid A containing endotoxins but also other cytokines inducing bacterial fractions. At the post-ultrafilter sampling port the LAL-test was < 0.005 to 0.034 EU/ml; IL-1 PBMC was below the detection limit (20 pg/ml) being 27 to 63 pg/ml at the pre-ultrafilter level. Polyamide ultrafiltration represents an efficient system to obtain an endotoxin-free dialysate and a single filter works up to 240 hours.

A randomized trial of cyclosporine in steroid-resistant idiopathic nephrotic syndrome

To compare the efficacy (induction of remission) and safety of cyclosporine (CsA) with those of supportive therapy in patients with steroid-resistant idiopathic nephrotic syndrome (INS), we organized an open, prospective, randomized, multicentric, controlled study for parallel groups, stratified for adults and children. Forty-five patients with steroid-resistant INS were randomly assigned to supportive therapy or CsA (5 mg/kg/day for adults, 6 mg/kg/day for children) for six months, then tapered off by 25% every two months until complete discontinuation. Four patients were lost to follow-up. During the first year 13/22 CsA-treated patients versus three of 19 controls attained remission of the nephrotic syndrome (P < 0.001). A symptom score was assessed at time 0 and at six months. The mean score significantly decreased in the CsA group (P < 0.001), but remained unchanged in the controls. At month 6 the mean urinary protein excretion, the mean serum proteins and plasma cholesterol had significantly improved in the CsA group but were not changed in the controls. There were no significant differences in serum creatinine and creatinine clearance between treatments (interaction time* treatments, P = 0.089 and P = 0.935, respectively) at month 6 versus basal. The CsA-related side-effects were mild; no significant difference in blood pressure between the two groups was seen at any time. This study shows that CsA can bring about remission in some 60% of patients with steroid-resistant INS. In patients with normal renal function and without severe hypertension, CsA at the therapeutic scheme adopted did not produce severe renal or extrarenal toxicity.

Conjugated diene fatty acids in patients with chronic renal failure: evidence of increased lipid peroxidation?

Conjugated diene fatty acids (CDFA) were evaluated by second derivative spectrophotometry in the plasma and adipose tissue of 42 chronic renal failure (CFR) patients in conservative treatment, 40 patients treated by hemodialysis (HD) with cuprophane, cellulose acetate or hemophan, 29 treated by hemodiafiltration (HDF) with polysulfone, polyacrylonitrile or polyamide, and 28 healthy controls. Plasma CDFA were also evaluated at the beginning, at 30 min and at the end of the dialytic session. CDFA were unchanged in CRF patients with creatinine clearance (Ccr) > 10 ml/min respect to the controls, CRF patients with Ccr < 10 ml/min showed a higher level of CDFA both in plasma and adipose tissue (p < 0.02). HD patients showed values similar to those of the control group. The lowest level of CDFA was found in HDF patients (p < 0.01 for plasma, p < 0.05 for adipose tissue versus both control and any other group). A significant relationship between plasma and adipose tissue CDFA was found in all groups. In the group of CRF patients with Ccr < 10 ml/min, females exhibited a higher level of CDFA both in plasma and adipose tissue. No significant change was found during dialytic session, independently from the membrane used. CDFA are not only primary products of lipid peroxidation, but also have a dietary origin, primarily from dairy products. Taking into account the reduced dietary intake, the increase in end-stage CRF may be due to an enhanced oxidative stress and/or to abnormalities in CDFA metabolism. Uremic patients, particularly in the predialytic stage, should be considered at risk for increased oxidative stress. HDF treatment better corrects the abnormality compared to conventional HD.

Very late activation-3 integrin is the dominant beta 1-integrin on the glomerular capillary wall: an immunofluorescence study in nephrotic syndrome

The expression of alpha 2; alpha 3; alpha 5; alpha 6-subunits of the beta 1 [very late activation (VLA)] integrin family was studied in kidney specimens using an immunofluorescent technique. 6 specimens from normal kidney were compared with 10 specimens from patients affected by various glomerulopathies [minimal change nephropathy (MCN), membranous nephropathy (MN) and systemic lupus erythematosus nephritis (SLEN)]. On normal glomeruli, alpha 3 was the dominant integrin, being mainly present on podocytes and showing a linear fluorescent pattern codistributed with laminin. In MCN and SLEN, alpha 3 presented a normal pattern. In MN, alpha 3 revealed a trabecular picture on thickened glomerular basement membranes. Moreover, in stage-III MN, a segmental loss of alpha 3-integrin was detected. In our opinion, VLA-3 may offer an interesting approach to the study of the relationships between podocytes and their substrate.

Prevalence of hepatitis C virus (HCV) antibodies in haemodialysis patients

The prevalence of antibodies to HCV and the course of hepatitis have been determined in 357 haemodialysed patients treated at a single institution. The prevalence of HCV infection increases with the duration of haemodialysis and with the use of blood transfusions, yet there is high frequency of HCV seropositivity even without blood transfusions. Evolution of HCV hepatitis to chronicity is frequent and biological signs of chronic hepatopathy can coexist with absence of alanine aminotransferase (ALT) abnormalities.

Behavior of antibody profile against hepatitis C virus in patients on maintenance hemodialysis

The prevalence of anti-hepatitis C virus (HCV) in dialysis setting is still a nonstandard datum. In particular, it is not known of the phenomenon is stable or increasing or decreasing, even in a given geographical area. We studied the behavior of anti-HCV prevalence during a 12-month follow-up in 415 hemodialysis patients treated at a single institution and belonging to a limited geographical area with standard HCV endemic. Point prevalence of anti-HCV has shown a tendency to growth linked in part of the incidence of infection, in part to new positivities in patients already on dialysis treatment. More than 50% of the new HCV-positive patients, had no history of classical parenteral transmission of the virus. These findings suggest that HCV infection is a phenomenon on the increase in dialysis units and that dialysis treatment emerges as an independent risk factor in contracting infection.

Liquid nitrogen snap frozen saphenous vein for vascular access in dialysis

In the authors' centers, fresh saphenous veins (FSV) procured from routine saphenectomies have been preferred to synthetic prostheses in cases of difficult vascular accesses (VA) for dialysis. The need for veins of different lengths and diameters prompted them to preserve SV by instantaneous freezing in liquid nitrogen since November 1987. Until now, 59 patients have received 35 FSV and 32 cryopreserved SV (CSV). Actuarial patency rates after 1 year are 82% and 72%, respectively. The 6-keto prostaglandin F1 alpha measured on punches of both veins showed residual production of prostacyclin even in CSV, but this was unresponsive to stimulation by arachidonic acid and bradykinin, or to inhibition by aspirin. In the authors' opinion, despite marked endothelial damage, satisfactory clinical results can be obtained by this very simple and cheap method of storing biologic prostheses for dialysis VA.

Improved biocompatibility by modified cellulosic membranes: the case of hemophan

The rising problem of biocompatibility is encouraging the development of new dialysis membranes, but the high cost of synthetic ones precludes their wide use. The authors compared the biocompatibility of cuprophan (CU), cellulose acetate (CA), and hemophan (HE), evaluating both in vitro and in vivo polymorphonuclear leukocyte (PMN) oxidative metabolism activation by resting chemiluminescence and complement activation by C3a; in vivo PMN counts during dialysis were also performed. The lowest increase in in vitro PMN resting chemiluminescence using HE was + 71.3% with CA, +49.3% with CU, and + 21.4% with HE (p less than 0.001 versus CA and CU); furthermore, HE did not significantly stimulate PMN resting chemiluminescence during in vivo hemodialysis: + 56.6% with CA, + 38.8% with CU, and + 3.7% with HE (p less than 0.01 versus CU and p less than 0.001 versus CA). C3a concentration increased with all membranes both in vitro and in vivo, but HE (in both experimental conditions) showed the lowest increase at any time (p less than 0.001 versus CA and CU). After 15 min of dialysis, PMN count dropped to 20.3% of basal values with CU, to 49.8% with CA, and to 76.5% with HE (p less than 0.001 versus CU and CA). Among cellulosic membranes, HE is the most biocompatible and appears to be an important step in preventing blood-membrane interactions and related complications.

Polymorphonuclear oxygen free radical production and complement activation induced by dialysis membranes as assayed in an experimental model

Activation of polymorphonuclear leukocytes with subsequent production of reactive oxygen metabolites has been reported to occur during hemodialysis related to a membrane bioincompatibility. We used an experimental dialysis model to evaluate, by chemiluminescence, the production of reactive oxygen metabolites and, by C3a, complement activation induced by cuprophan, cellulose acetate, hemophan, polysulfone, polyacrylonitrile, polymethylmethacrylate or polyvinyl chloride blood lines alone. No differences were obtained in the system, at time 30 min compared to initial values, as far as zymosan-activated chemiluminescence is concerned; resting chemiluminescence increased markedly with cellulose acetate (+71%), cuprophan (+49%), polymethylmethacrylate (+22%), hemophan (+21%) but had no variation with polysulfone, polyacrylonitrile and blood line. The time course of C3a levels up to 120 min showed a marked rise with cuprophan and cellulose acetate, a moderate increase with hemophan, polysulfone and blood line, and a decrease with polymethylmethacrylate and polyacrylonitrile. The results obtained documented a different behavior of the production of reactive oxygen metabolites compared to complement activation and support the hypothesis that the production of reactive oxygen metabolites by polymorphonuclear leukocytes is stimulated not only by complement activation but also by a direct dialysis membrane interaction.

Oxidative metabolism of polymorphonuclear leukocytes and serum opsonic activity in chronic renal failure

Luminol-amplified chemiluminescence was used to study the oxidative metabolism of polymorphonuclear leukocytes (PMN), in resting state and in response to opsonized zymosan, in 65 patients with different degrees of chronic renal failure (CRF) or on regular dialysis treatment (RDT). Every patient was compared on the same day with a normal subject. Furthermore, the serum opsonic activity was evaluated, cross-matching zymosan opsonized by serum from CRF-RDT patients and normals with PMN from CRF-RDT patients and normals. PMN resting chemiluminescence showed a progressive increase inversely related to the glomerular filtration rate, and it remained high in patients on RDT. Zymosan-activated chemiluminescence indicated a deficit in phagocytosis for PMN of patients with a glomerular filtration rate lower than 10 ml/min, persisting in RDT patients. The serum opsonic activity was always significantly lower in CRF and in RDT patients than in the control group; this defect was already present in patients with mild renal impairment. Our findings suggest that PMN from CRF or RDT patients have an increased reactive oxygen metabolite production in the resting state that may cause cell and tissue damage; the opsonization impairment and the decreased PMN phagocytic activity contribute to increased vulnerability to infection in these patients.

Acid-base balance during biofiltration (BF)

Acid base balance during biofiltration (BF): Six patients on standard acetate hemodialysis (HD) were switched to BF with 1 m2 AN69-S membrane, 12 hours weekly (BF-4h) and, later on, to a stage with 1.2 m2 AN69-S, 9 hours weekly (BF-3h). During BF, in order not to exceed 25 mEq/l in intradialytic arterial HCO3, arterial acid-base was examined hourly and a mean of 178 and 199 mEq of HCO3 respectively were infused in BF-4h and BF-3h. We obtained a better control of acidosis with a reduction of the intradialytic pCO2 decrease and hypoxemia. The amount of HCO3 infused was related to the patients deficit in HCO3 total pool and therefore it can be predicted, to avoid postdialytic alkalosis.

[Increased muscular irritability syndrome: treatment with nifedipine. Report of a case]

In 1980 Alberca et al. described a patient with a syndrome of increased muscle irritability, who presented ondulating muscle rolling movements and electrically silent cramps, myoedema and muscle reactions to mechanical stimulation similar to myotonic response, suggesting a disfunction at myofibrillar level. We saw a similar case, of a male patient, 21 years of age, who complained of cramps of severe intensity for the past four years. These cramps were painful in the upper and lower limbs and impaired his locomotion; they were electrically silent. At percussion the patient showed severe idiomuscular contraction, with a period of increased relaxation, similar to a myotonic reaction and also, prolonged myoedema and rolling muscle contractions. Electromyography was normal, as were histochemical and electron microscopy studies. We carried out a therapeutic trial with niphedipine (a calcium antagonist), on the assumption that the patient showed a disturbance of the myofibrillar function--even though physiopathogenesis of the hyperirritability muscle syndrome was not yet clearly defined--and with a basis on the importance of the intracytoplasmatic level of Ca++ free in the muscle contraction mechanism, not only as the initiating factor of the contractile process, but also as a quantitative controller of the mechanic tension development through regulation of the amount of ATP metabolized during muscle activity. Administration of the drug in a dose of 40 mg daily, per os, brought a remission of the symptoms after two weeks, and the patient could walk normally again. On the introduction of a placebo, on two different opportunities, there occurred a recrudescence of the symptoms after about one week's time.(ABSTRACT TRUNCATED AT 250 WORDS)

[Transcutaneous renal needle-biopsy guided with ultrasonics]

Authors performed percutaneous renal biopsy guided by ultrasounds in 10 patients in whom urography was dangerous or did not provided good renal images. The advantages of this method are in the directional and dimensional accuracy of ultrasound scanning, so that the exact topography of the kidney can be established. The use of ultrasonically guided renal biopsy is mainly recommended in iodine medium idiosyncrasy, in myelomas and renal failure. This method can be preferred in order to establish the exact topography of kidney, in acute anuric renal failure, in chronic failure (when high doses of iodate contrast are needed), and in the presence of cyst.

Long-term use of a "stable" bicarbonate containing dialysate

We present an original method for the preparation of "stable" dialysate containing 35 mEq/l of bicarbonate. The dialysate was utilized with 4 patients for periods ranging from 4 months to 1 year according to a short-term recirculated dialysis schedule in closed circuit (20-40L) (2-2 1/2 hrs) on alternate days. Preliminary results are reported here with respect to the tollerance of the dialytic run and correction of the acid-base balance equilibrium. The clinical tollerance is excellent despite high dehydration rates even in patients particularly sensitive to ultrafiltration. The acidosis correction would seem to be much better with bicarbonate than with traditional dialysis. The difference is even higher if we consider the brevity of the dialysis. During the bicarbonate dialysis we do not observe any fall of the PCO2 or significant difference in PO2 in the patient's blood. The correction of acidosis probably causes the normalization of pre-dialytic potassiemia in spite the "net" removal of K with short dialysis is considerably less.

Cytogenetical and dermatoglyphic studies in patients affected by Steinert's myotonic dystrophy

Cytogenetic and dermatoglyphic studies were performed in 10 patients affected by Steinert's myotonic dystrophy. No anomalies were found in karyotype and dermatoglyphs in these patients, except for an occasional chromosomal translocation.

[Simultaneous evaluation total and selective of GFR and ERPF with Hypaque-131I and with Hippuran-125I (author's transl)]

The Authors report their experience regarding the use of radioisotopes (Hypasults obtained in 40 healthy subjects confirm the reliability of the separate tests. Limitation and value of plasmatic and urinary clearances are briefly discussed. As the methods are simple, reproducible and unharmful for the patient, the Authors suggest an increasing application of these radioisotopic techniques for clinical purposes.

[Anatomo-clinical studies and therapeutic results in 2 cases of essential mixed cryoglobulinemia with renal insufficiency]

Two cases of essential mixed cryoglobulinaemia selected from a personal series on account of their clinical features (hyperviscosity syndrome in one case and frank renal involvement in the other) are presented. Extensive seroimmunological examinations were carried out, along with histopathological studies designed to reveal significant changes in organs and tissues, particularly the skin and kidneys. Reference is briefly made to the debate pathogenesis of the immunological phenomenon that probably lies at the root of the disease. A short account is also given of attempts at treatment with corticosteroids, immunosuppressors and plasmapheresis.