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A Thea

Publications and source records attributed to A Thea.

At least 19 recordsLinked to original sources

[Complex vascular access].

Availability of a proper vascular access is a basic condition for a proper extracorporeal replacement in end-stage chronic renal failure. However, biological factors, management and other problems, may variously condition their middle-long term survival. Therefore, personal experience of over 25 years has been critically reviewed in order to obtain useful information. In particular "hard" situations necessitating complex procedures have been examined but, if possible, preserving the peripherical vascular features.

Animals

Correlations between bone histopathology and serum biochemistry in uremic patients on chronic hemodialysis.

To define which noninvasive investigations are of value in predicting bone histology, we analyzed transiliac bone specimens (66 biopsies, 14 autopsies) from 80 uremic patients on chronic dialysis. Results were compared with values of different measurements of parathyroid hormone (PTH), alkaline phosphatase (APH), osteocalcin, calcitonin, baseline and post-deferroxamine (DFO) aluminium (Al),--beta 2 microglobulin, ferritin and bone mineral density. Among histomorphometric parameters, woven osteoid, active osteoblastic surface and resorption surface showed the best correlations with dynamic and biochemical marks of active bone metabolism. Among biochemical parameters, intact PTH and APH were better related to histomorphometric and dynamic bone parameters than other PTH measurements as well as osteocalcin, while calcitonin was related to no parameters. Stainable Al alone, and not total bone Al content was related to bone histology. Baseline Al was related to lamellar osteoid, while post-DFO Al was related to stainable Al. beta 2 microglobulin was positively related to active osteoid surface and ferritin was inversely related to the mineral apposition rate, while bone mineral density was related only to total bone volume. We conclude that, though definite diagnosis requires the use of histological methods, few simple biochemical parameters may offer insight to the bone metabolic status, useful to the physician in day to day clinical practice.

Absorptiometry, Photon

Scleroderma renal crisis is still a life-threatening syndrome.

Scleroderma renal crisis (SRC) was known as a rare and catastrophic syndrome responsible for acute renal failure (ARF) in a context of widespread microvascular disease occurring in progressive systemic sclerosis (PSS). Following pathogenetic hypoteses, angiotensin converting enzyme (ACE) inhibitors, plasma infusions (PI), and plasma-exchange (PE) have been employed in SRC with favorable results. Our purpose was to verify whether these therapies have consistently changed the fatal prognosis of SRC, even in our experience. In the last 10 years, SRC was diagnosed in eight patients (all eight with histologic data). The first five cases were treated with steroids, antihypertensive-cocktail, and PI: all five died, two within 48 hours, three after 10, 15, and 300 days, respectively. Three other patients were treated with ACE inhibitors, PI, and PE: all three died after 1, 9, and 12 months of HD. Clinical-histological correlations showed a strong relationship between the extent of glomerular involvement and the degree of renal failure, while arterial lesions seem to be more related to the past history of PSS, independently from the previous existence of hypertension. We conclude that "true" SRC diagnosed by restrictive criteria is still a rare life-threatening syndrome, and, unfortunately, no clear predictive biochemical or clinical signs could be identified; vascular renal involvement correlates to the duration of PSS independently of previous clinical evidence of renal failure or hypertension; a glomerular pattern similar to that reported for hemolytic-uremic syndrome (HUS)/thrombotic thrombocytopenic purpura (TTP) syndrome is directly related to the degree of acute renal involvement; SRC may occur even in the absence of hypertension, mainly if cardiomyopathy is present: in our experience. ACE inhibitors and plasma therapies have changed the short-time prognosis of SRC, but they may be unable to provide recovery from dialysis and do not avoid further evolution of extrarenal PSS exiting in late death.

Adult

Hemolytic-uremic syndrome during recombinant alpha-interferon treatment for hairy cell leukemia.

We report a case of hemolytic uremic syndrome in a patient suffering from hairy cell leukemia during recombinant alpha-interferon treatment. We believe that this is the first report of the occurrence of this peculiar kind of acute renal failure following alpha-interferon therapy. This association may suggest possible speculations regarding side effects of interferon treatment and pathogenesis of hemolytic uremic syndrome.

Biopsy

Concomitant iron and aluminum mass transfer following deferoxamine infusion during hemofiltration.

Variable tissue overloading can alter the removal rate of iron and aluminum from uremics. Owing to its higher affinity to deferoxamine (DFO) and higher plasma concentrations, Fe could impair Al removal in cases of simultaneous body burden. Fe and Al plasma kinetics and mass transfer were therefore studied in 12 uremic patients with different Fe and Al status: six with normal ferritin levels (less than 400 micrograms/L [ng/mL]), and Al 1.4 to 4.7 mumol/L (40 to 131 micrograms/L) (group A); six with increased ferritin (greater than 2,000 micrograms/L), and Al 1.7 to 17 mumol/L (47 to 476 micrograms/L) (group B). DFO (40 and 80 mg/kg in a random sequence) was administered once a week during the first hour of the first hemofiltration (HF). The results show that in both groups and with both DFO doses, maximum Fe and Al mass transfer was achieved in the first and second HF, respectively. The 80-mg/kg dose of DFO significantly raised Al mass transfer in both groups, whereas Fe mass transfer was only slightly affected. Even though plasma Fe levels were almost always higher than Al, Al mass transfer eventually exceeded that of Fe, in both Fe-normal and Fe-overload patients. The bias towards Al in mass transfer was enhanced in both groups in the second HF, and at the higher DFO doses. Thus, DFO once a week reduced Fe loss to less than 30 mumol/wk in patients with normal ferritin levels. In both Fe and Al overloaded patients, Al can be removed, and Al mass transfer may often exceed Fe mass transfer, depending on the degree of tissue burden, the time from DFO infusion, and the DFO dose.

Adult

Clinical and histological results of long-term management of aluminium overloading in uraemic patients with desferrioxamine.

Aluminium introxication in uraemic patients has been reported both in epidemic and sporadic forms. Desferrioxamine (DFO) results in strong Al mobilisation, but definitive treatment schedules, times of stop, and actual long-term Al removal her not been established. This study was carried out on three sporadic cases of Al intoxication treated with DFO for 3 1/2, 4 1/2 and 1 years. Clinical and laboratory parameters were employed to check the brain, bone and red cell status. Direct evaluation of Al kinetics showed that actual Al removal may be overestimated. In our experience it did not exceed 100 mg/year, and the ratio (DFO used/Al removed) decreased to 150 g/25 mg after two years of DFO, though considerable tissue deposits persisted in the patient who died after 3 1/2 years of treatment. Despite unexplained EEG worsening, neurological symptoms improved. Relapses, however, occurred after many years of DFO. Bone status improvement, at least in parathyroidectomised patients, proved to be only partial and time-related. The therapeutic effectiveness of DFO in these patients seemed to be exhausted after two years even if Al deposits had not vanished.

Adult

Prevention and treatment of aluminum overload in uremic patients: long-term results.

The authors evaluate the efficacy of a protocol of prevention and treatment of aluminum (Al) overload in RDT patients during a 7-year period (from 1981, 164 patients, to 1987, 161 patients). Al in dialysate solutions was always less than 25 micrograms/l. Baseline Al levels greater than 100 micrograms/l were found in 22% of patients in 1981 but in none in 1987, while the percentage of values less than 60 micrograms/l increased from 55 to 91%. DFO tests were positive in 54% and 7% of cases in 1981 and 1987, respectively. A clinical diagnosis of Al intoxication was performed in 6 patients in 1981, and no further cases were diagnosed later. DFO treatment (50 mg/kg once a week) was employed preventively in 31 patients owing to positive DFO-tests, and in the 6 Al-intoxicated patients therapeutically. In the former patients none developed clinical intoxication. In the latter group clinical improvement was only temporary in the three parathyroidectomized patients. Al hydroxide [Al(OH)3] as a phosphate binder was tapered off in 1981 and substituted by Al-free chelants. In 1987, 66% of patients were given CaCO3 or Mg (OH)2 alone or in association, while 34% still needed Al(OH)3, although at low dosages (less than 2 g/day). The conclusion is that such a protocol is able to prevent and to treat cases of Al intoxication, albeit only partially.

Adult

Hypervitaminosis B12 in maintenance hemodialysis patients receiving massive supplementation of vitamin B12.

We have administered routinely a multivitamin preparation containing a megadose of B12 to 106 hemodialysis patients after dialysis treatments. We found that these patients had very high levels of serum vitamin B12 which returned to original values only after a period of three years after stopping the vitamin. Discontinuing therapy had no effect on hemoglobin, mean erythrocyte corpuscular volume, or motor nerve conduction velocity. It is not known whether maintaining a prolonged high level of vitamin B12 is harmful. However, animal and epidemiologic studies have suggested that both cobalamin and cobalt may be potentially toxic. In view of the absence of demonstrable benefit and the possible risk of toxicity, we believe that the use of such megadose vitamin compounds in dialysis patients should be re-evaluated.

Adult

Direct interaction between polymorphonuclear neutrophils and cuprophan membranes in a plasma-free model of dialysis.

Plasma-free, purified, normal, human polymorphonuclear neutrophils (PMN) were recirculated for 60 minutes in an experimental model of dialysis using cuprophan membranes and acetate or bicarbonate dialysate. At different time intervals, the intracellular contents of PMN-derived cationic proteins (NCP), the release of lysosyme, beta-glucuronidase and PAF as well as the occurrence of PMN and platelet aggregating activities in the supernatants were evaluated. The formation of PMN aggregates, the depletion of intracellular contents of NCP together with the release of lysosomal constituents occurred early (5-10 min) in the course of recirculation. These events were concomitant with the occurrence of PMN aggregating activity in the supernatants due to the release of NCP, as it was antagonised (30-40%) by a rabbit anti-human NCP, and to the release of PAF which also accounted for the platelet aggregating activity that was independent from both adenosine diphosphate and cyclo-oxygenase inhibitors. These data suggest that direct interaction occurs between human PMN and cuprophan in in vitro conditions in the absence of plasma factors and point to a role for cellular mediators in the pathogenesis of the intravascular alterations occurring early in haemodialysis.

Cell Aggregation

Urokinase treatment for arteriovenous fistulae declotting in dialyzed patients.

Urokinase treatment, previously employed with success in the declotting of deep venous thrombosis and arteriovenous shunts in patients undergoing regular dialytic treatment (RDT), was used in 23 cases of arteriovenous fistula thrombotic occlusion in 18 RDT patients. The treatment was successful in 65.2% of the cases without any negative side effects, except 1 case which may have developed a pulmonary embolism. Patients with severe hypofibrinolysis may need larger doses or may have a recurrence of the thrombotic episode. All therapeutic failures correlated with the presence of fibrosis or sclerosis.

Adult