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Biomedical subjects

M Feriani

Publications and source records attributed to M Feriani.

At least 91 records · Page 5Linked to original sources
PubMed1984

The role of neurotransmitters in the genesis of uremic encephalopathy.

To classify the influence of neurotransmitters in the genesis of uremic encephalopathy we studied cerebrospinal fluid (CSF) and plasma (P) amino acid (AA) concentration, in patients undergoing various dialytic treatments (hemodialysis = HD, intermittent and continuous peritoneal dialysis = IPD and CAPD). HD causes a significant decrease in CSF/P ratios of branched chain AA (BCAA) and a significant increase in CSF Glycine/Valine ratio, suggesting an augmented brain uptake of Glycine at detriment of Valine. In IPD the general trend of Aromatic AA/BCAA ratio suggests a preferential transport of Aromatic AA through the blood brain barrier. The differences between IPD and HD are confirmed by data concerning metabolites of Serotonin and Dopamine: CSF concentrations of 5- Hydroxyindoleacetic acid and Homovanillic acid are low in HD but high in IPD. So, a reduced (in HD) and an increased (in IPD) activity of monoamine systems could be at the basis of some neurological disturbances appearing in uremia.

Adolescent↗
PubMed1982

Changes of cerebral density in dialyzed patients.

CT studies were made on 38 patients receiving different dialytic treatment, 10 patients with chronic renal failure not yet dialyzed, and 15 healthy subjects. No morphological modifications were observed. On the contrary, significant changes of density were demonstrated after a dialysis session in the population treated intermittently. In these patients the density values were similar to those registered in the controls 1-6 h after a dialysis session. End stage renal failure and CAPD patients always had normal density values. Therefore cerebral density changes are caused only by the intermittent dialytic treatment.

Absorptiometry, Photon↗
PubMed1982

Studies on brain density in hemodialysis and peritoneal dialysis.

30 patients on hemodialysis or peritoneal dialysis have been investigated by computerized tomographic (CT) scan. To evaluate possible cerebral alterations induced by dialysis, CT examinations were carried out before, immediately after and 6 h after the end of dialysis with an Evaluskop, which provides an objective precise evaluation of even slight variations in brain density. No morphological variations were noted after dialysis, while the brain density fell significantly during and after the treatment. A decrease in density was not observed in normal subjects or in patients on continuous peritoneal dialysis. The changes in the densitometric values of brain tissue suggest that there is a postdialysis gain in cerebral water linked to the intermittent treatment. CT may represent a simple reliable method for studying uremic encephalopathy and investigating the pathogenesis of the dialysis disequilibrium syndrome.

Adolescent↗
PubMed1982

Anatomical bases of peritoneal permeability: a reappraisal. Anatomy of peritoneum.

The peritoneal membrane consists of flat mesothelial cells linked together with digitations and containing vesiculae with pinocytic capacity, of endothelial cells (containing Weibel-Palade's bodies and vesiculae) and of an interstitial tissue consisting of a network of watery channels. The cellular structures of mesothelium and endothelium are characterized by tight and gap junctions or perhaps by macular junctions. The visceral peritoneum shows a prevalence of gap junctions, the pericysic veins contain only tight junctions while both types can be found in the arterioles. Two different ways for solute transport are theoretically possible: the vesicles of plasmalemma (via pinocytosis) and the junctions (via size-sieving effect). Studies with tracers did not furnish unequivocal data on this problem and did not clarify if these structures could be the equivalent of the pores of the Landis-Pappenheimer's theory. The studies of Karnowsky and Simionescu, using tracers, have in fact given opposite results.

Animals↗
PubMed1982

Pharmacokinetics of intravenous and intraperitoneal cefuroxime during peritoneal dialysis.

We investigated the pharmacokinetics of cefuroxime sodium, a new parenteral beta-lactam antibiotic, in 15 patients with stable chronic renal failure during intermittent peritoneal dialysis (IPD). Eight patients were administered 1 g cefuroxime as an intravenous bolus 1 h before the start of dialysis. Mean plasma levels of cefuroxime fell from 80 mcg/ml at 1 h to 40 mcg/ml at 6-8 h. At 24 h, concentrations were higher than 20 mcg/ml. In peritoneal fluid cefuroxime reached 16.7 mcg/ml at 1 h and 7.55 mcg/ml at 6 h. Seven patients received cefuroxime added to the dialysis solution at a dose of 2.5 g/10 liters. After 6 h of dialysis, cefuroxime reached plasma levels of 60 mcg/ml; after 24 h, concentrations were 37.5 mcg/ml. These results demonstrate that cefuroxime, administered by the i.v. route, easily diffuses from blood to peritoneal fluid and, from peritoneal fluid to blood when added to the dialysis solution. In both cases concentrations reached by cefuroxime are sufficient to treat peritoneal infections associated with peritoneal dialysis.

Adult↗
PubMed1981

Acid-base balance on peritoneal dialysis.

Forty studies of acid-base balance during intermittent peritoneal dialysis (IPD) and during continuous ambulatory peritoneal dialysis (CAPD) were performed on 20 patients who were receiving IPD with acetate buffer (5 patients), IPD with lactate buffer (5 patients), CAPD with acetate buffer (5 patients) and CAPD with lactate buffer (5 patients). Measurements of acetate, lactate and pyruvate levels in blood and dialyzate were taken at different times during dialysis; blood samples for blood gas analysis were drawn at the same times. Calculations of the kinetics of acetate, lactate and bicarbonate during IPD and CAPD were carried out according to the method of Tolchin [1977] but modified for PD. Thus it was possible to quantify the balance of the buffers, their mass transfer rates, bicarbonate generation and the percentage of buffer converted to HCO3. IPD kinetics of acetate and lactate were found to be similar, the main difference being a lower and significant percentage conversion of lactate to bicarbonate (45%) compared to that of acetate to bicarbonate (71%) (P < 0.005). On CAPD the kinetics of the two buffers was quite different: while the serum lactate level was always low (mean 0.97 +/- 0.33 mM/l), the acetate level was always high (mean 5.12 +/- 3.34 mM/l). Thus the utilization of the two buffers during "acute intermittent" treatment (IPD) and "continuous" treatment (CAPD) is different. On IPD there are no important differences between the two buffers, whilst on CAPD lactate seems to be better and safer than acetate; for instance, serum HCO3 values are relatively constant with lactate (27.7 +/- 2.13 mM/l) while with acetate there is a trend to exceed physiological values (29.5 +/- 1.7 mM/l). When acetate is used in the dialyzate for CAPD the concentration must be less than 38.5 mM/l.

Acetates↗
PubMedDate not supplied

Use of different buffers in peritoneal dialysis.

A buffer is included in the peritoneal dialysis solution in order to offset the hydrogen ions normally produced during the metabolic processes. Nowadays, the buffer used is lactate, and its concentration in conventional peritoneal dialysis fluids is 35 or 40 mmol/L. Despite the general thought that peritoneal dialysis adequately corrects uremic acidosis, several studies have demonstrated that more than 50% of patients present mild to moderate acidosis with the solution containing 35 mmol/L of lactate, although with a 40 mmol/L solution this percentage decreases, a substantial number of patients still remain acidotic. This acid-base derangement is characterized by a normal pH and a below-normal plasma bicarbonate concentration, although the external body base balance is in equilibrium. There is evidence that this condition contributes to uremic osteodystrophy and has a detrimental effect on protein metabolism. Conventional solutions also affect mesothelial cell viability and local leukocyte function and have potential systemic effects such as the impairment of cellular redox state. New solutions containing pure bicarbonate or a mixture of bicarbonate and lactate have recently been investigated. A bicarbonate solution containing 34 mmol/L significantly increased plasma bicarbonate levels as compared with the lactate 35 mmol/L solution. It has been demonstrated that bicarbonate solutions have better biocompatibility than the lactate buffered solution and substantially reduce abdominal discomfort experienced by a certain percentage of patients during the solution infusion. These studies demonstrated that the bicarbonate-buffered CAPD solution is safe, well-tolerated, and does not present any, even potential, side effects. Thus, it seems reasonable to consider the bicarbonate buffered solution the standard instead of the alternative, and it might entirely replace lactate as buffer in peritoneal dialysis fluid.

Buffers↗
PubMedDate not supplied

Oxalate removal by differing dialysis techniques.

Secondary hyperoxalemia is a common feature in patients with chronic renal failure, but oxalate removal is not adequately accomplished by regular dialysis treatment. Oxalate removal in two groups of patients, 11 on continuous ambulatory peritoneal dialysis (CAPD) and 12 on hemodialysis (HD), was investigated. HD patients were studied during a regular bicarbonate dialysis and during hemodiafiltration (HDF) with a high convective component (UF = 66 mL/min) and AN69 filter (Hospal Filtral 12, 1.2 m2, Hospal Industrie, Meyzieu, France). All HD and HDF spent dialysate and all 24 hr CAPD effluents were collected; oxalate concentration was measured by high performance liquid chromatography (HPLC) using an ion exchange column. Both oxalate flux and total extraction were statistically higher during HDF treatments (HDF = 1.87 +/- 0.77 mg/min and 335.9 +/- 131.5 mg/session, respectively; HD = 0.99 +/- 0.74 mg/min, 226 +/- 153 mg/session, respectively; p < 0.02). The positive interaction of convective and diffusive fluxes probably played a major role in oxalate removal during treatment with a high convective component; solute-membrane interactions can occur by using either cellulosic or synthetic fibers. In CAPD patients, oxalate removal (76.42 +/- 50.85 mg/day) was lower than in patients on either HD or HDF, although weekly oxalate extraction was statistically no different between CAPD (535.46 +/- 356 mg/week) and HD (677.72 +/- 460.82 mg/week). It was concluded that HDF is more effective than HD or CAPD in oxalate removal. Long-term studies are needed to demonstrate whether these kinetic findings have clinical relevance.

Adult↗
PubMedDate not supplied

Acid-base balance in peritoneal dialysis.

In patients without functioning kidneys, alkali replenishment is accomplished by the addition, via dialysis solution, of either HCO 3 - itself or a metabolic precursor of this anion, such as lactate. The body base balance in peritoneal dialysis (PD) patients is self-regulated by the feedback between plasma bicarbonate concentration and dialytic base gain. Dialytic base gain is the only source of buffer for PD patients and this gain should counteract the metabolic acid production. Dialytic base gain depends on peritoneal buffer fluxes (lactate reabsorption minus bicarbonate lost). The plasma bicarbonate level is determined by the dialytic base gain and the metabolic acid production. Bicarbonate buffered PD solution provides some advantages over the conventional lactate buffered PD solution.

Acetates↗
PubMedDate not supplied

The importance of ultrafiltration on acid-base status in a dialysis population.

The amount of fluid withdrawn by ultrafiltration in a dialysis session plays an important role in regulating the acid-base status of patients. It has been previously demonstrated that an interdialytic weight gain of 3 kilograms requires the removal of 3 liters, mostly of extracellular fluid, which may contain 60-70 mMols of bicarbonate. Such losses require an increase in the buffer mass transfer to achieve a good buffer balance. The importance of interdialytic weight gain (IWG) on acid-base status was evaluated in two significantly different periods. In the period where the IWG was lower, predialytic pH and HCO3 were significantly higher than in the alternate period. Since dialysis schedule, dialysate buffer, daily protein intake and given medications did not differ during the two periods, we conclude that a reduced ultrafiltration due to less weight gain betters predialytic acid-base status.

Acid-Base Equilibrium↗
PubMedDate not supplied

Technical and clinical evaluation of a new system for ultrafiltration control during hemodialysis.

A new system for ultrafiltration control during hemodialysis is described. The apparatus consists of a computer operated system of load cells that register variations in weight of the outlet dialysate versus inlet dialysate. Once the weight loss of the patient has been established, the gravimetric control operates on the dialysate circuit to obtain the transmembrane pressure adequate to achieve the desired ultrafiltration rate and patient weight loss. The system can be used as a complete dialysis machine or as a separate module that can be adapted to any standard dialysis machine. This module was tested in more than 220 dialysis sessions, using different membranes and ultrafiltration rates. The difference between the scheduled and the real weight loss was always less than 100 g at the end of the dialysis session. The number of technical interventions required were few, as was the rate of complications related to the system. The system is safe and reliable and offers a low cost opportunity to improve dialysis tolerance by accurate and progressive ultrafiltration during the session.

Body Weight↗