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Biomedical subjects

G Panzetta

Publications and source records attributed to G Panzetta.

At least 19 recordsLinked to original sources
PubMed2001

Validation of a simple method for assessing sodium intake in dialysis patients.

It has been reported that sodium intake can be estimated in dialysis patients by the increment in the body sodium pool from the end of a dialysis session to the beginning of the following one. To verify the reliability of this method we compared the sodium intake, estimated by the interdialytic changes in plasma sodium concentration (C) and body water volume (V), to sodium removal during three consecutive sessions. For this purpose we investigated 9 nondiabetic patients, 5 females and 4 males, under chronic hemofiltration treatment. Sodium intake was estimated by the formula (C(pre) V(pre)) - (C(post) V(post)) using a flame photometer and electrical bioimpedance to determine the plasma sodium concentration and total body water, respectively. Sodium removal was calculated by the difference between sodium loss into the ultrafiltrate and sodium gain with the reinfusion fluid. The mean values of sodium intake calculated during the three intervals corresponded with the sodium losses measured during the three hemofiltration sessions in each patient (338+/-55 vs. 329+/-67 mEq; r = 0.92, p<0.0001). A direct relationship was also observed between sodium intake and both interdialytic body weight increase (r = 0.89, p< 0.0001) and fluid loss during the sessions (r = 0.88, p<0.0001). This data demonstrates that sodium intake can be properly estimated by the interdialytic changes in body water and plasma sodium concentrations. They also suggest that fluid intake may be influenced by sodium consumption and that sodium intake monitoring could be useful for the control of excessive interdialytic fluid gain.

Aged↗
PubMed2000

Dynamic magnetic resonance imaging in the assessment of chronic medical nephropathies with impaired renal function.

We examined the value of dynamic magnetic resonance imaging (MRI) in chronic renal disease with renal insufficiency. In 33 consecutive patients (21 vascular nephropathy, 12 glomerular nephropathy) MRI was performed using a 1.5-T unit and a body coil, with SE T1-weighted (TR/TE = 600/19 ms) and dynamic TFFE T1-weighted sequences (TR/TE = 12/5 ms, flip angle = 25 degrees ) after manual bolus injection (via a cubital vein) of 0.1 mmol/kg Gd-DTPA-BMA. Morphological evaluation was performed in unblinded fashion by three radiologists, evaluating renal size, cortical thickness, and corticomedullary differentiation. Functional analysis was performed by one reviewer. Time-signal intensity curves, peak intensity value (P), time to peak intensity (T), and the P/T ratio were obtained at the cortex, medulla, and pyelocaliceal system of each kidney. The relationship of these parameters to serum creatinine and with creatinine clearance was investigated. A good correlation between morphological features of the kidneys and serum creatinine values was found. Morphological findings could not distinguish between vascular and glomerular nephropathies. A statistically significant correlation (P <0.01) between cortical P, cortical P/T, medullary P, and serum creatinine and creatinine clearance was found. A significant correlation (P <0.01) was also found between cortical T, medullary P/T, T of the excretory system, and creatinine clearance. The cortical T value was significantly higher (P <0.01) in vascular nephropathy than in glomerular nephropathy. Thus in patients with chronic renal failure dynamic MRI shows both morphological and functional changes. Morphological changes are correlated with the degree of renal insufficiency and not with the type of nephropathy; the functional changes seem to differ in vascular from glomerular nephropathies.

Aged↗
PubMed1998

Acetate-free biofiltration versus bicarbonate haemodialysis in the treatment of patients with diabetic nephropathy: a cross-over multicentric study.

BACKGROUND: Morbidity and mortality rates in diabetic patients on regular dialysis treatment (RDT) are higher than in non-diabetic-subjects on RDT. Moreover, diabetic patients experience an intradialitic morbidity unacceptably higher than in patients with other causes of terminal renal failure. The aim of the present investigation was to compare standard bicarbonate haemodialysis (BHD) with acetate-free biofiltration (AFB) in a group of 41 diabetic patients stable on dialysis treatment for 25 +/- 22 months. METHODS: Twenty-four type II and 17 type I diabetic patients, all requiring insulin therapy, were included and were followed for 1 year in a 6-month cross-over randomized study for both methods. The analysis was carried out on dialysis symptoms, interdialysis symptoms, and nutritional status, and the multivariate analysis of variance for repeated measures on the same subjects in the two techniques was used. RESULTS: AFB significantly reduced dialytic and extradialytic symptoms (P=0.003 and 0.001 respectively). Cardiovascular collapses decreased by 43%, and other dialysis symptoms showed a similar trend (-35%). The interdialysis symptoms decreased by 28% and were accompanied by an increase in subjective wellbeing (39%) when patients were switched from traditional haemodialysis to AFB. Acid base control was better with AFB (P=0.01), both at the beginning and during the session. Slightly significant differences were also obtained for Kt/V (AFB 1.48 +/- 0.29 vs BHD 1.38 +/- 0.30), while no significant difference was noted with respect to sodium mass balance, nutritional status, calorie-protein intake, nPCR, blood glucose profile, and insulin requirements. The number of hospital admissions and the mortality rate, which were much lower during the AFB than the BHD period, were not analysed statistically. CONCLUSIONS: AFB allows better control of some metabolic aspects, reduces intra- and extradialysis symptoms, and improves patient quality of life. Whether the long-term prognosis can be improved by AFB remains to be established with further studies.

Acetates↗
PubMed1998

Acetate free biofiltration (AFB): from theory to clinical results.

Acetate free biofiltration (AFB) is a hemodiafiltration technique based on a buffer-free dialysate and bicarbonate infusion in the postdilution mode. The performance of AFB requires a dialysis machine equipped with an automatic control system to balance the infusion rate to that of ultrafiltration. The filters employed are usually polyacrylonitrile hollow-fiber hemodialyzers. A 145 mEq/l sodium bicarbonate solution is generally used and the infusion rate is regulated at about 8-10 liters per session to ensure optimal convective removal of toxins as well as to compensate for the bicarbonate lost in the dialysate. During AFB bicarbonate transfer results from the balance between diffusive and convective bicarbonate losses in the dialyzer and the amount of bicarbonate infused in the venous return. Thus bicarbonate supply can increase along with the rise in plasma bicarbonate concentration until a steady state is reached when the rate of infused bicarbonate equals bicarbonate losses into the dialyzer. A mild alkalosis may sometimes occur which can be avoided by slightly reducing bicarbonate concentration and/or infusion rate during the session. In spite of the large amount of sodium infused and the unusual high chloride concentration in the dialysate, no difference in the postdialysis plasma sodium levels nor in chloremia has been observed between AFB and bicarbonate dialysis. This is essentially due to the very large removal of these anions by convection (chloride and sodium) and by diffusion (sodium) into the dialyzer. Similarly the significant convective losses of calcium suggest a high dialysate calcium concentration to avoid negative intradialytic calcium balance. Polyacrylonitrile membranes, regularly employed in AFB, allow the passage of endotoxin fragments to the blood circuit in a lesser extent than other membranes. Coupled with the fact that a buffer-free dialysate and a sterile bicarbonate infusion are used AFB can be considered a highly biocompatible dialysis technique. As compared to conventional dialysis AFB allows adequate removal of small molecules and better removal of larger molecules such as beta2-microglobulin. In the short run AFB is characterized by an increase in cardiovascular stability: it improves dialysis symptoms and the subjective well-being of patients. A better acid-base correction is regularly reported together with a rise in some nutritional indices like serum albumin levels. The reasons for these favorable results are not well defined yet. A number of multicenter studies on the effects of AFB have been published with quite similar results, but most of them are non-randomized, and use historical controls. Only one prospective, cross-over study comparing bicarbonate dialysis with AFB in diabetic dialysis patients is available. It concludes that in a six-month observation period with AFB it is possible to better control some metabolic aspects and to improve both treatment tolerance and patients' life quality. However, it is not known whether these positive effects may entail better long-term prognosis; moreover, comparisons between AFB and conventional dialysis were never designed to ascertain the role of the dialysis membrane from that of the other components of AFB on clinical results. Therefore, large prospective trials with long observation periods are necessary to clarify the mechanisms through which AFB might be superior to conventional dialysis as well as the impact of these techniques on long-term prognosis. In such studies other relevant factors such as rehabilitation and life quality of the patients, which have been generally neglected in previous surveys, must also be included to evaluate cost-effectiveness of this therapy.

Acidosis↗
PubMed1997

Autonomic nervous function during haemodialysis assessed by spectral analysis of heart-rate variability.

1. Short-term autonomic response to haemodialysis-induced hypovolaemia was studied in 30 patients undergoing chronic haemodialysis by analysing power spectra of heart-period variability. Patients were classified as haemodynamically stable (15 patients) and unstable (15 patients) according to their past history of cardiovascular collapse during the treatment. Blood volume, systolic arterial pressure and heart period were measured during sessions that ended without the occurrence of collapse. 2. No significant differences were observed when comparing blood volume, heart rate and arterial pressure of stable and unstable patients during the dialysis, and the two groups could not be distinguished merely on the basis of these haemodynamic parameters. Conversely, spectral analysis of beat-to-beat heart-period variability showed markedly different power patterns: in stable patients power was mainly in the low-frequency (LF) band (0.06-0.15 Hz), whereas in unstable patients it was mainly in the high-frequency (HF) band (0.15-0.4 Hz). 3. The efficiency of the autonomic response to hypovolaemia was evaluated by the ratio between the powers in the LF and HF bands. Stable patients exhibited an LF/HF power ratio systematically greater than unstable patients during the entire dialysis, and on the basis of this index the two groups were clearly separated. 4. Results obtained with spectral analysis lead us to conclude that reduced efficiency in the autonomic control of cardiovascular functions could be the main cause of the haemodynamic instability of patients prone to collapse.

Aged↗
PubMed1996

Echo color Doppler imaging of carotid vessels in hemodialysis patients: evidence of high levels of atherosclerotic lesions.

Cardiovascular disease is the major cause of death in patients with end-stage renal disease, and the incidence of atherosclerosis-related complications is significantly higher in dialysis patients than in nonuremic controls. This study aimed at evaluating atherosclerotic involvement of carotid vessels in hemodialysis patients and in a group of subjects with a similar cardiovascular risk factor pattern using echo color Doppler ultrasonography. Carotid lesions have been evaluated, taking into account plaque characters (surface, echogenicity), the most severe luminal narrowing, and the number of vessels involved. A large number of vascular plaques has been observed in uremic patients: 73.8% versus 44% in the control group (chi square test = 10.98; P < 0.01). A high prevalence of carotid lesions has been found in both patients and controls with clinical evidence of cardiovascular complications. Finally, we have considered the presence of carotid lesions with a topographic evaluation. The presence of atheromatous lesions in hemodialysis patients compared with control subjects was statistically significant different in all the vessels except common carotid (internal carotid: chi-square test = 8.59, P < 0.01; external carotid; chi-square test = 13.46, P < 0.01; bulb chi-square test = 7.90; P < 0.01). Our data clearly show that the hemodialysis population suffers from a higher degree of atherosclerosis than age- and sex-matched controls with similar cardiovascular risk patterns, suggesting that the uremic state in conservative and substitutive treatment per se may contribute to "advanced" atherosclerosis. However, this does not enable us to state that hemodialysis accelerates atherosclerosis. In fact, the progression of atherosclerosis might be related to atherogenic factors operative before regular dialysis.

Aged↗
PubMed1995

Protein intake does not depend on the dose of dialysis delivered--provided Kt/V is adequate.

BACKGROUND: A link between malnutrition and the dialysis dose has been recently postulated on the basis of the direct relationship between Kt/V and nPCR and an increase in dialysis therapy has been also proposed in malnourished patients or when nPCR is less than 1 g/kg b.w., but the clinical meaning of such a relationship is unclear. DESIGN: Both dietary protein intake and nPCR were simultaneously determined in a selected population of 35 well-dialysed patients (Kt/V > 0.8) and were related to the delivered dialysis dose. RESULTS: No relationship was found between measured Kt/V (1.10 +/- 0.20) and dietary protein intake (PI, 0.98 +/- 0.20 g/kg) and similarly no relationship was evident between the dialysis dose and nPCR (0.99 +/- 0.20 g/kg). Although the mean nPCR value was similar to that of protein intake, nPCR exceeded protein intake when PI was less than 1 g/kg b.w. CONCLUSION: Our results demonstrate that if the dialysis dose is adequate, protein intake is a dialysis--independent or patient--dependent variable. They also show that at least 0.9 to 1.0 g protein per kg b.w are required to maintain nitrogen balance even in well-dialysed patients.

Adult↗
PubMed1995

Autonomic nervous function and blood volume monitoring during hemodialysis.

We studied the autonomic reflex response to hypovolemia during HD by means of spectral analysis of heart rate variability (SAHRV) in 10 hypotension prone (group A) and 10 hemodynamically stable patients (group B). UF rate normalized per total body water and blood volume fall were similar in the two groups. The sympatho-vagal balance index, calculated as the ratio between the integrals of the spectrum in the low (0.02-0.15 Hz) and in the high frequency range (0.2-0.35 Hz) rose in group B progressively from the beginning of the treatments, reaching a top at the 90th minute and remained subsequently high until the end. On the contrary this index did not show remarkable increases in group A. The differences between the two groups were statistically significant at 0 (4.6 +/- 2.9 vs 1.5 +/- 1.3), 60th (8.3 +/- 7.8 vs 2.2 +/- 2.6), 90th (17.9 +/- 13.4 vs 3.7 +/- 2.8), 150th (8.8 +/- 3.7 vs 2.7 +/- 2.8) and 210th minute (8.6 +/- 5.0 vs 2.9 +/- 2.5). In conclusion SAHRV shows an impairment of autonomic reflex response to hypovolemia in hypotension-prone patients.

Adult↗
PubMed1993

The 59-kDa polypeptide constituent of 8-10-nm cytoplasmic filaments in Neurospora crassa is a pyruvate decarboxylase.

The fungus Neurospora crassa harbors large amounts of cytoplasmic filaments which are homopolymers of a 59-kDa polypeptide (P59Nc). We have used molecular cloning, sequencing and enzyme activity measurement strategies to demonstrate that these filaments are made of pyruvate decarboxylase (PDC, EC 4.1.1.1), which is the key enzyme in the glycolytic-fermentative pathway of ethanol production in fungi, and in certain plants and bacteria. Immunofluorescence analyses of 8-10-nm filaments, as well as quantitative Northern blot studies of P59Nc mRNA and measurements of PDC activity, showed that the presence and abundance of PDC filaments depends on the metabolic growth conditions of the cells. These findings may be of relevance to the biology of ethanol production by fungi, and may shed light on the nature and variable presence of filament bundles described in fungal cells.

Amino Acid Sequence↗
PubMed1993

The contribution of hemofiltration among the treatment modalities of chronic uremia.

To assess the role of hemofiltration (HF) among different treatment modalities, we reviewed our clinical material from 37 patients that consecutively underwent the treatment from 1981 on. A number of 12 patients on HF for at least 1 year deliberately switched to hemodialysis (HD) or hemodiafiltration (HDF) were studied retrospectively. Biochemical and nutritional parameters, cardiovascular aspects and morbidity data were collected during one year before and after the treatment change. A sodium balance study was performed in 9 patients during HF as well. No significant differences in plasma urea, creatinine, phosphate, body weight, serum albumin, transferrin, hemoglobin and PCR were found. BUN tended to be lower during HD-HDF because of the more efficient removal of urea with these treatments. Indeed, the Kt/V index was 0.91 during HF and it was 1.15 with HD-HDF. There were no differences in hypotensive episodes and morbidity. Sodium loss was strictly related to body fluid removal during HF session with a net sodium loss (NSL) of 128 mEq per liter of fluid removal (FR) (NSL = 6.44 + 122 FR; r:0.83; p < 0.01). Adapting sodium concentration of substitution fluid to patients weight gain, cardiovascular stability improved in those subjects more prone to collapse. With equivalence in PCR during the 2 periods, although Kt/V was 20% lower during HF, it seems reasonable to assume that the lower urea clearance might be compensated by the more efficient removal of higher molecular weight substances and/or by the improved biocompatibility of HF.

Aged↗
PubMed1992

Red blood cells and platelet membrane fatty acids in non-dialyzed and dialyzed uremics.

Three groups of patients with chronic renal failure (CRF), 16 non-dialyzed, 16 undergoing haemodialysis (HD), 16 undergoing continuous ambulatory peritoneal dialysis (CAPD), and 48 controls were examined. We analyzed the fatty acid composition in membranes from erythrocytes and platelets and the platelet malondialdehyde (MDA) production as an index of thromboxane metabolism. Marked differences in erythrocytes fatty acid composition were observed between patients with CRF and controls and, particularly, among the three groups of patients with CRF. Patients on CAPD were characterized by an increase in oleic acid, while haemodialyzed had a marked increase in arachidonic acid. Platelet fatty acid composition showed similar differences, suggesting a 'systemic' membrane abnormality. Platelet MDA was increased in haemodialyzed and positively correlated with the platelet arachidonate content.

Adult↗
PubMed1990

The protein catabolic rate as a measure of protein intake in dialysis patients: usefulness and limits.

To test the validity of the determination of protein catabolic rate (PCR) as a measure of protein intake in dialysis patients, we studied a selected population of 27 well-dialysed patients, free of catabolic illnesses, and in apparent clinical stability. Daily protein intake, obtained by controlled dietary records, and protein catabolic rate, measured by urea kinetic modeling, were 1.02 +/- 0.26 and 0.99 +/- 0.16 g/kg respectively. Although there was a good correspondence between protein intake and protein catabolic rate in many of our patients, in the six cases with dietary protein content less than 0.8 g/kg, protein catabolic rate was regularly greater than 0.8 g/kg; on the contrary, in four patients ingesting more than 1.2 g/kg of protein, protein catabolic rate values were significantly less than protein intake. Our results demonstrate that some degree of nitrogen imbalance may be present in about 25% of clinically stable dialysis patients, and suggest that current concepts of clinical stability do not imply a stable metabolic state in a substantial portion of dialysis patients. Therefore, protein catabolic rate determination does not provide a reliable index of protein intake in many dialysis patients.

Adult↗
PubMed1989

Expression of pregnancy specific beta 1-glycoprotein gene in human placenta and hydatiform mole.

Transcriptional studies of the placental protein Pregnancy Specific beta 1-Glycoprotein (SP1 or PS beta G) gene with a cDNA probe in Northern blot analysis showed 15-20 folds mRNA increase in term placenta compared with early placenta and hydatiform mole. This value parallels the SP1 amount translated in wheat germ cell-free system. We conclude that SP1 biosynthesis is regulated at transcriptional level during placental development and a similar mechanism would occur in hydatiform mole which is a hyperplastic trophoblast tumor.

Bacteriophage lambda↗