Biomedical subjects
Publications and source records attributed to A Baraldi.
The various components in the N 1s photoemission spectra of amorphous carbon nitride are identified by measuring their photon energy dependence and comparing the experimental results with ab initio multiple scattering calculations. The intensity modulations with photon energy are due to the extended x-ray absorption fine structure effects.
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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.
During the past 10 years the type of vascular access for haemodialysis procedures have changed markedly in our centre: more elbow AV fistulae and more central venous catheters are now used. Nevertheless, early referral to nephrologists and availability of central venous catheters and peritoneal dialysis allow elderly people to be admitted for dialysis treatment. Since vascular access for haemodialysis plays a key role in patient well-being, it is mandatory to apply quality assurance criteria to vascular access for haemodialysis surgery. Based on the results of a national survey, in Italy this policy is still in its early stages: monitoring of vascular access differs amongst centres, interventional radiology is used in a differing way, planning of vascular access for haemodialysis in pre-dialysis patients often remains an unsolved problem. According to our initial experience, we propose the use and validation of a quality-index [(minimum success rate) in elective vascular access for haemodialysis surgery], allowing accreditation of a department and a single surgeon for access management. Prevalence of central venous catheters at first dialysis of chronic renal failure patients is also proposed to evaluate the efficiency in access planning. Better knowledge of vascular access management by different teams could eventually lead to definition of guidelines for this 'Cinderella of dialysis'.
1. Stroke-prone spontaneously hypertensive rats (SHRsp) have been used widely to test agents putatively capable of vascular protection. These animals present an accelerated time course of hypertension and a reduced life-span. When fed a high-sodium diet from the eighth week of life, a further acceleration in blood pressure increase is obtained, and rats start to die after 5 weeks of diet as a consequence of cerebral haemorrhage. In this model, angiotensin-converting enzyme (ACE) inhibitors were repeatedly proved to prevent vascular lesions and death. Notably, this effect was independent of any hypotensive effect. On the contrary, diuretics were shown not to be equally effective. A combination of ACE inhibitors and diuretics, although known to have synergistic effects in the therapy of hypertension, has never previously been tested. 2. Our aim was to study the effects of long-term treatment with the ACE inhibitor delapril (12 mg day-1 kg-1), the thiazide-like diuretic indapamide (1 mg day-1 kg-1), and their combination (12 and 1 mg day-1 kg-1 respectively), on the survival of SHRsp rats fed a high-sodium diet from the eighth week of life onwards. The effects of the treatments on blood pressure, body weight, food and fluid intake, diuresis, proteinuria and the appearance of lesion signs and death were assessed weekly. When control rats reached 50% mortality, they were killed, together with some drug-treated rats, to compare lesions in brain and kidney. The other drug-treated rats continued treatments until 50% mortality was reached in two treatment groups. 3. All drug treatments were able to delay death significantly when compared with control rats, which reached 50% mortality after 6 weeks of salt loading. This event was preceded by a highly significant increase in proteinuria, diuresis and fluid intake that took place 3 weeks after the increase in blood pressure over the initial range. In delapril- or indapamide-treated SHRsp these changes were never seen, even when animals started to die. In the combination-treated group, a significant increase (P < 0.01) in fluid intake and diuresis, but not proteinuria, was observed from the third week of treatment onwards. 4. Treatment with delapril or indapamide did not block the progressive increase in blood pressure as observed in control animals. However, the increase in blood pressure was markedly retarded with respect to control rats. At variance with this, in combination-treated animals blood pressure levels were maintained until the end of the experiment within the 99% confidence interval initially observed in control animals. 5. Infarctual and haemorrhagic cerebral lesions were observed in 38% of control rats; no lesions were noted in brains of age-matched rats receiving a drug treatment. Kidneys from control animals presented major degenerative lesions of glomeruli and arteries, characterized by fibrinoid necrosis. This condition was absent in drug-treated animals, which presented minor signs of ischaemic lesion. Heart hypertrophy, when heart weight was expressed as a percentage of body weight, was similar in saline-, delapril- or indapamide-treated rats. At variance with this, in combination-treated animals the heart weight to body weight ratio was significantly (P < 0.01) lower than in the other groups. 6. In conclusion, the diuretic indapamide showed similar protective effects as the ACE inhibitor delapril on acute vascular lesions and survival of SHRsp. Moreover, their combination synergized in preventing heart hypertrophy consequent to longterm hypertension. This results is probably related to the enhanced diuresis and the better control of blood pressure levels selectively found in combination-treated animals.
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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.
The effect of the urinary calcium concentration (CaU) on erythrocyte morphology was studied by incubating erythrocytes in urine with prefixed CaUs of 5, 10, 20 and 40 mmol/l by addition of CaCl2. The same experiment was carried out on erythrocytes preincubated with levo-verapamil (l-V) at 10, 100 and 200 mumol/l. Phase contrast microscopy observations were performed at 0, 30, 60, 120, and 240 min by 2 experienced investigators. At 0 min the erythrocytes showed a clear extraglomerular pattern. At 60 min marked morphological and volumetric alterations were evident when the CaU was > or = 10 mmol/l. On the contrary, no change was found when red cells were treated with > or = 100 mumol/l l-V, independent of the CaU. Dysmorphic erythrocyturia has been related to transglomerular passage even if it was sporadically observed in hypercalciuric or lithiasic patients. This work suggests a role for a high CaU in causing the formation of microcytic and warped erythrocytes. In our opinion, in hypercalciuric urine the appearance of dysmorphic or mixed hematuria does not necessarily indicate transglomerular passage.
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The expression and distribution pattern of beta 1 (alpha 1-alpha 6) and alpha v beta 3 integrins and ICAM-1 and VCAM-1 counter receptors were evaluated by an immunohistochemical technique on eight renal samples from patients affected by rapidly progressive glomerulonephritis (RPGN) of different aetiologies. In all cases integrins and counterreceptors displayed similar patterns. On tubular cells of renal cortex, a marked upregulation of alpha 2 beta 1, alpha 3 beta 1, alpha 5 beta 1, alpha v beta 3 integrins and VCAM-1 was observed with as many as 60-90% of tubular cross-sections labelled, while a strong ICAM-1 reactivity was limited to the luminal surface. The same adhesion molecules were also uniformly expressed on crescentic cells. In glomeruli, integrin upregulation occurred only on apparently preserved capillary tufts, i.e. in an early stage of lesion, while collapsed and sclerotic tufts showed a reduced integrin expression. In addition a morphometric study of extracellular matrix (EM) proteins cellular fibronectin and tenascin showed a 9.56 +/- 1.9-fold and 3.35 +/- 0.6-fold increase respectively in these proteins, as compared to normal kidney (P < 0.001). The upregulation of alpha v beta 3 on podocytes might play a role in the adhesion of crescentic cells. An increased production of cytokines, in particular transforming growth factor-beta, might induce augmented deposition of EM proteins and upregulation of beta 1 and beta 3 integrins in RPGN.
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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.
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