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Biomedical subjects

G La Greca

Publications and source records attributed to G La Greca.

At least 19 recordsLinked to original sources
PubMed1992

Total gastrectomy: nutritional status after different reconstruction techniques. An experimental study.

The authors report their experimental studies on early nutritional changes in 30 gastrectomized rats where intestinal continuity was restored by three different reconstruction methods, i.e., exclusion of the duodenum from alimentary transit (Sweet-Allen method), or duodenal recanalization (Longmire method) or double duodenal and jejunal recanalization (Moricca method). Ten sham operated rats were used as controls. Results showed that the group of rats which underwent Longmire's reconstruction presented better nutritional parameters (body weight gain, daily food intake, feeding efficiency, albuminemia) than the Moricca and Sweet-Allen reconstruction groups. These results became statistically significant when follow up was extended to 18 months by using an actuarial method. However, perioperative mortality rate was highest in the Longmire reconstruction group.

Anastomosis, Surgical↗
PubMed1992

A new scintigraphic method to characterize ultrafiltration in hollow fiber dialyzers.

Ultrafiltration and pressure profiles in hollow fiber dialyzers with different hydraulic permeabilities have been investigated with a new scintigraphic method. Radiolabelled albumin macroaggregates, used as a nondiffusible marker molecule, were added to the blood in an in vitro circuit and circulated through cuprophan and polysulphon dialyzers. Since the marker molecule was too big to cross the dialysis membrane, its changes in concentration were assumed to occur in response to the variation of the blood water content (filtration or back-filtration). These changes in concentration, recorded by a gamma camera, were evaluated to establish the cumulative values of filtration and back-filtration and their relevant profiles along the length of the dialyzer. The achieved data were compared with the experimental values of ultrafiltration empirically measured and with the theoretical values predicted by a classic linear method. Two conditions were analyzed: A) the minimal filtration rate necessary to avoid back-filtration (critical filtration); and B) the condition of zero net filtration in which filtration equals back-filtration. The nuclear method proved to be extremely precise in predicting the ultrafiltration values and significantly more precise than the linear method, especially for the highly permeable dialyzer. The reason for that probably depends on the non-linear pressure and ultrafiltration profile observed with the scintigraphic pattern of the dialyzer. Viscosity changes and local variations in blood flow may in fact interfere with the pressure drop inside the hollow fibers and result in such a complex behavior. The other interesting aspect of this method is the possibility of accurate measurement of the amount of back-filtration that wouldn't be possible with simple calculations. In conclusion, the complex nature of the phenomena regulating the water fluxes in hollow fiber dialyzers requires more complex calculation than a simple linear model to achieve an accurate range of predictability.

Biophysical Phenomena↗
PubMed1992

Dynamic catheterography in the early diagnosis of peritoneal catheter malfunction.

The dynamic catheterography is an image technique that allows to study the peritoneal solution inflow and outflow phases in case of catheter malfunction. The examination is carried out in three subsequent steps: 1) direct examination without contrast media in order to define the position of the catheter inside the abdomen; 2) low speed catheterography by normal injection of 10 ml of hydrosoluble contrast medium to verify the patency of the cannula; 3) high speed catheterography by 30 ml hydrosoluble dye injected with an automateds high pressure system to study the inflow phase, the fluid distribution in the peritoneal cavity and the patency of the catheter holes. Different radiographic patterns can be found: dislocation of the catheter tip, KinKing, one way obstruction, inner lumen obstruction. The procedure is simple, safe and reliable for a correct diagnosis and for the choice of a successful therapeutic approach to peritoneal catheter malfunction.

Catheterization↗
PubMed1991

Effect of dialysate and substitution fluid buffer on buffer flux in hemodiafiltration.

The effect of differing dialysate and substitution fluid buffer types and concentrations on acid-base balance have not been assessed in patients treated with hemodiafiltration for ESRD. To determine bicarbonate, acetate, lactate and total buffer flux, mass balance studies were performed in patients treated with hemodiafiltration using four different combinations of dialysate and substitution fluids. Driving force for bicarbonate flux was assessed in all treatments. Bicarbonate flux depended on bicarbonate driving force and ultrafiltration rate. Bicarbonate flux was negative in all treatment combinations, even when the driving force was positive. Acetate flux was positive in all treatment combinations, but the net magnitude was small. Lactate flux, when lactate containing substitution fluid was used, varied with dialysate buffer employed during treatment. Overall buffer flux depended on the bicarbonate driving force, ultrafiltration rate, and varied with the type of substitution and dialysate buffer employed. The types and concentrations of buffer used in dialysate and substitution fluid have important effects on the acid-base balance of patients treated with hemodiafiltration. The long-term implications of different therapeutical choices in these patients is unknown.

Acetates↗
PubMed1991

Multicentric study on paired filtration dialysis as a short, highly efficient dialysis technique.

Paired filtration dialysis (two-chamber haemodiafiltration) was evaluated as a short, highly efficient renal replacement therapy in 35 uraemic subjects belonging to three different dialysis centres. The study period was 1 year. Patients were divided into two groups according to their body-weight and drinking habits. The smaller patients underwent 150-min dialysis sessions three times weekly. The larger patients underwent 3-h treatments thrice weekly. The treatment was adequate in all patients according to the KT/V criteria of adequacy. The intradialytic symptomatology was remarkably low and the treatments were well tolerated in all patients. The study confirms the reliability of paired filtration dialysis as a short dialysis technique. In some patients 150 min may be insufficient to achieve an adequate dialysis efficiency and 180 min may be required for the majority of the population.

Adult↗
PubMed1991

A multicenter, selection-adjusted comparison of patient and technique survivals on CAPD and hemodialysis.

Four hundred and eighty CAPD and 373 HD patients started regular dialysis treatment between 1981 and 1987 in 6 dialysis centers. The CAPD patients were 6 years older, on average, than the HD patients and had more complicating conditions (43.3% with 3 or more coexisting risk factors versus 28.9% with coexisting complications). The 7-year patient survival rate was not significantly different. Cox's proportional hazards regression showed that age, cardiovascular disease, cerebrovascular disease, peripheral vascular disease, diabetes, malignancy and multisystem disease had significant adverse effects on patient survival. After correcting for the influence of these factors, no significant differences in patient survival were seen. However, after 53.5 years of age, the increase in the risk of death was significantly higher in HD than in CAPD patients. Technique survival was significantly different in the 6 centers and was better for HD than for CAPD. There was no statistically significant difference between CAPD and HD technique survival when peritonitis was eliminated as a cause of failure. Based on this 7 year analysis, CAPD would appear to be an excellent alternative to HD.

Female↗
PubMed1991

Ultrafiltration and pressure profiles in continuous arterio-venous hemofiltration studied by computerized scintigraphic imaging.

Clotting of the filters in continuous arterio-venous hemofiltration (CAVH) has been frequently related to filtration pressure equilibrium (FPE). The geometry of the filter and the blood flow, together with filtration fraction, are the factors affecting FPE. A new method based on scintigraphic imaging of the filter is described to demonstrate FPE and identify the operational conditions influencing it. A radiolabelled marker molecule (albumin macroaggregates + Tc99) is added to the blood circulating at various flows through the filter. Changes in the concentration of this molecule detected by a gamma camera are used to calculate the water fluxes in different sections of the filter. When the curve reaches a plateau, no further changes occur and FPE is achieved. The study used Amicon D-30 hemofilters and FPE points were achieved for blood flows of 75, 110 and 150 ml/min respectively 8 cm, 12 cm and 18 cm from the inlet. The study not only demonstrates the occurrence of FPE, but also identifies the length of the filter required at a given blood flow to avoid FPE (achieving less clotting and lower heparin requirement). The Amicon diafilter family, having filters of different length, is useful for "personalizing" the filter in CAVH.

Blood Coagulation↗
PubMed1990

[Idiopathic varicocele: incidence in 517 subjects].

A sample population of 517 subjects was screened in order to evaluate the incidence of idiopathic varicocele. Subjects were examined clinically and underwent tests using a Doppler flow-meter. Following a brief introduction to the didymoepididymal disease, the findings of the study are reported. In conclusion, the important role of orthostasis as a causal factor leading to the onset of disease in subjects with a predisposition to diathesis is underlined.

Adult↗
PubMed1990

Paired filtration dialysis: studies on efficiency, flow dynamics and hydraulic properties of the system.

Several strategies have been proposed to increase dialysis efficiency in order to reduce dialysis treatment time. Paired filtration dialysis (two-chamber technique) is a new technique combining the advantages of highly permeable membranes and convective transport with the high depurative efficacy of diffusion. The system operates with two units in series (hemofilter + dialyzer) with membranes of polysulfone and hemophan, respectively. A detailed analysis of the hydraulic properties of the system and its possible optimization in terms of depurative efficiency is reported in this paper. In vitro and in vivo tests provided data sufficient to draw some hypotheses on a new utilization of the system. The system appears to be adequate for operating under conditions of high blood flows, however, some limitations were evidenced during our evaluation: the convective component may be insufficient and further increases are impossible because of the limiting effect of the low surface area of the hemofilter; the configuration in which the weight loss is achieved in the hemofilter exposes to the risk of backfiltration in the dialyzer, reducing the benefits of a highly biocompatible system, and the use of acetate in the dialysate and/or lactate in the substitution fluid may interfere with a satisfactory correction of metabolic acidosis. On the basis of our evaluations, some changes can be proposed such as: (1) increased surface area of the hemofilter; (2) use of blood flows higher than 300 ml/min; (3) use of bicarbonate in the dialysate and in the replacement solution; (4) increased convective component with ultrafiltration rates of 50-60 ml/min and full replacement with substitution fluid in between the two filters, and (5) weight loss achieved in the dialyzer with a constantly positive transmembrane pressure. With such a modification of the operative conditions, paired filtration dialysis can be probably applied as a highly efficient dialysis technique in a large number of patients with a significant reduction of dialysis treatment time.

Blood Flow Velocity↗
PubMed1990

Fluctuation of vasopressin secretion in chronic hypernatremia.

Herein we will describe a case of chronic hypernatremic-hyperosmolar syndrome with cerebral localization of systemic sarcoidosis. Several determinations of plasma arginine vasopressin (p-AVP) at various plasma sodium levels were carried out in this patient. During the study p-AVP values varied between 2.6 and 9.5 pg/ml. A high percentage of them was related to plasma osmolality, pointing out that p-AVP secretion was osmotically mediated. This behavior is in contrast with the tendency of hypernatremic patients previously reported in the literature, in whom p-AVP values were inappropriately low for the corresponding degree of plasma osmolality, suggesting that vasopressin secretion was not influenced by osmotic stimulation. Furthermore, our case, unlike those previously described, showed high values of urinary osmolality. In conclusion, our patient represents, in essence, the 'middle' of the spectrum of the hypodipsic-hypernatremic syndrome, because she is to be inserted between the majority of patients who have little or no osmotically mediated AVP release and the case of a child, recently described, who had completely normal AVP secretion.

Arginine Vasopressin↗
PubMed1990

Alpha-1-antichymotrypsin in renal biopsies.

Alpha 1-Antichymotrypsin (alpha 1-AK) and alpha-1-antitrypsin (alpha 1-AT) represent a defense mechanism to protect the tissues from proteolytic enzyme activity. We studied the implication of alpha 1-AK and alpha 1-AT in glomeruli of patients with different nephropathies based on the analysis of 52 paraffin-embedded renal biopsies with alpha 1-AK and alpha 1-AT antisera. The results demonstrate an intense alpha 1-AK glomerular staining in renal biopsies from patients with minimal-change disease, while a minor staining of this protein was found in the other nephropathies. No significant evidence of alpha 1-AT deposits was observed in our cases. Our findings suggest that when alpha 1-AK is lacking in glomeruli the defense mechanisms against proteolytic enzymes may not be efficient enough to protect the glomerular structures and limit the damage. Since alpha 1-AK is a reactant of the acute phase of inflammation, it may be considered as a marker of activity for monocyte-macrophages in glomerular damage.

Biomarkers↗