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Biomedical subjects

G La Greca

Publications and source records attributed to G La Greca.

At least 37 records · Page 2Linked to original sources
PubMed2000

Impact of biofeedback-induced cardiovascular stability on hemodialysis tolerance and efficiency.

BACKGROUND: Hypotension is caused by a drop in blood volume during ultrafiltration, followed by vasoconstriction and reduced perfusion in some regions of the body. METHODS: We carried out a prospective controlled crossover study on 12 hypotension-prone patients with two different modalities: (A) acetate-free hemodiafiltration with standard ultrafiltration control, and (B) acetate-free hemodiafiltration with monitoring of blood volume and automatic biofeedback with machine-driven adjustments on ultrafiltration and dialysate conductivity. We measured urea Kt/V and equilibrated Kt/V (eKt/V), urea rebound, and urea removal. Hypotensive episodes and interventions were recorded. RESULTS: In group B, fewer hypotensive episodes were recorded (24 out of 72 in group B vs. 59 out of 72 in group A). Saline infusion was required in 57 cases in group A and 15 cases in group B. Urea Kt/V was 1.34 +/- 0.08 in group A and was 1.26 +/- 0.06 in group B; eKt/V was much higher in group B (1.12 +/- 0.05) than in group A (1.03 +/- 008). A significantly higher rebound was observed in group A (14.2 +/- 2.7%) compared with group B (6.4 +/- 2.3%). Discussion. A greater solute sequestration seems to occur during hemodialysis with hypotension. This results in lower eKt/V, enhanced postdialytic rebound, and lower solute removal. Higher efficiency can be observed when dialysis is carried out smoothly and cardiovascular stability is maintained. We conclude that new systems for blood volume monitoring and automatic biofeedback may not only reduce the number of hypotensive episodes during dialysis, but may also contribute to significantly increase the efficacy of the treatment.

Adult↗
PubMed2000

Hemodiafiltration with online regeneration of the ultrafiltrate.

The concept of regeneration of dialysis fluids and of ultrafiltrate in particular has been recently revisited. Hemodiafiltration with online regeneration of the ultrafiltrate allows the concomitant infusion of sodium, calcium, and bicarbonate. Here, we studied the adsorptive characteristics of an integrated two-step sorbent system relative to different solutes present in the ultrafiltrate: sodium, calcium, phosphate, bicarbonate, uric acid, creatinine, and beta2-microglobulin. In vitro studies were performed in order to differentiate the relative roles for each sorbent (mineral-activated charcoal or hydrophobic resin) in adsorbing a given solute. Ex vivo studies were performed in order to evaluate the presence of cytokines (interleukin-1 beta and tumor necrosis factor-alpha), of cytokine (interleukin-1 beta and tumor necrosis factor-alpha)-inducing activities, and of the cytokine release in response to exogenous bacterial lipopolysaccharide by normal whole blood incubated with ultrafiltrate samples obtained at 15, 120, and 240 minutes after the start of treatment. The results of the present studies show the presence of immunomodulatory substances in the ultrafiltrate and the significant (P < 0.01) increase in the lipopolysaccharide-induced release of both interleukin-1 beta and tumor necrosis factor-alpha. The biological relevance of the ultrafiltrate and the possible relevance of the online, endogenous reinfusion are discussed.

Adsorption↗
PubMed2000

The final word.

Explore the source record for details and available documents.

Humans↗
PubMed2000

Role of antigenemia assay in the early diagnosis and treatment of CMV infection in renal transplant patients.

AIM: CMV antigenemia by direct pp65 antigen detection and quantification was monitored on a weekly basis during the first 3 months after kidney transplantation. SUBJECTS AND METHODS: Preemptive therapy with ganciclovir was started according to the following criteria: any positive antigemia in CMV-NEG subjects, a single determination > or = 30 cell or a two fold increase of positive cells in two consecutive specimens in CMV-POS and continued until pp65 was cleared. Overall, 109 patients were monitored. RESULTS: Among the 24 CMV-NEG patients, 13 (54%) developed a pp65 positive assay without symptoms and were treated. Ten patients remained CMV-infection free and one patient developed late onset (7 months) CMV disease (hepatitis). Among the 85 POS patients 15 (17%) developed a pp65 positive assay and were treated. Two of them developed CMV disease within 7 days of the onset of positive antigenemia and 13 were asymptomatic. The other 70 patients remained CMV-infection free. The interval between transplant and the onset of CMV infection was 39 +/- 13 days in the CMV-NEG group and 64 +/- 20 days in the CMV-POS group (p < 0.001). The peak antigenemia level was 193 +/- 175 cells in the CMV-NEG group and 55+/- 78 cells in the CMV-POS group (p < 0.001). The duration of treatment did not differ in the two groups (22 +/- 7days). A second course of therapy, due to a relapse of asymptomatic infection was performed in 11/13 (85%) treated CMV-NEG patients and in 2/15 (13%) treated CMV-POS patients. CONCLUSIONS: Among the total 28 treated patients, we observed only 6 episodes of mild creatinine increase and 9 episodes of mild neutropenia. In the overall population, we observed 8 systemic infections not related to CMV.

Antigens, Viral↗
PubMed2000

[Characterization and prognostic value of colorectal adenomas with molecular genetic markers].

AIM: The study analyses the expression of DNA-ploidy, ki-67, PCNA and p-53 and their role as potential markers of the development of colorectal adenomas. METHODS: 34 adenomas of the large intestine were analysed using endoscopic exeresis in 15 males and 13 females with a mean age of 64 years (range 42-80). Flow cytometric analysis was carried out to calculate the DNA-index and immunohistochemical tests were used to evaluate ki-67, PCNA and p-53. Statistical analysis was based on chi 2 test and Student's "t"-test. RESULTS: The DNA index was not statistically correlated with the histotype and grading. Ki-67 was highly positive in 5 adenomas, 2 aneuploids and 3 diploids, but did not show a clear relationship with other growth parameters. On the contrary, p-53 was statistically correlated with the more advanced degenerative state of adenomas, being pathological in 6 cases (30%), all with marked aneuploidy (p < 0.02) and severe dysplasia (p < 0.004). PCNA, which was also pathological (> 40%) in 4 (23.5%) aneuploid adenomas with severe dysplasia (2 villous and 2 tubulo-villous), appeared to be significantly correlated with the DNA index (p < 0.005), showing a proliferative index of exceptional clinical importance. CONCLUSIONS: The results of this study show that p-53 and PCNA are two parameters that contribute to the definition of the degenerative risk and allow patients to be selected for constant monitoring, although additional follow-up data are essential to enable the clinical verification of these results.

Adenoma↗
PubMed2000

[Migration of the catheter of a totally implantable venous system. A rare mechanical complication].

Catheter migration, represents a rare, mechanical complication following the use of totally implantable venous devices. A case, in which the catheter was inserted into the right internal jugular vein by percutaneous route, without radiological control, is described. Following the chemotherapy infusion drugs, the patient developed a catheter displacement and subcutaneous extravasation. Etiological hypotheses and modalities of prevention are discussed.

Female↗
PubMed2000

Dialysate flow distribution in hollow fiber hemodialyzers with different dialysate pathway configurations.

UNLABELLED: The efficiency of a hemodialyzer is largely dependent on its ability to facilitate diffusion, since this is the main mechanism by which small solutes are removed. The diffusion process can be impaired if there is a mismatch between blood and dialysate flow distribution in the dialyzer. The objective of the paper was to study the impact of different dialysate compartment designs on dialysate flow distribution and urea clearances. Eighteen hollow fiber 1.3 m2 hemodialyzers were studied, 6 each of 3 designs: Type A--standard fiber bundle (PAN 65DX Asahi Medical, Tokyo, Japan); Type B--spacing filaments external to the fibers (PAN 65SF Asahi Medical, Tokyo, Japan); Type C--fibers waved to give Moiré structure (FB130 Nissho-Nipro, Osaka, Japan). IN VITRO STUDIES: 3 dialyzers of each type were studied following dye injection into the dialysate compartment. Dynamic sequential imaging of longitudinal sections of the dialyzer were undertaken, using a new generation helical CT scanner (X-Press/HS1 Toshiba Corporation, Tokyo, Japan). In vivo studies: 3 dialyzers of each type were studied, in randomized sequence, in 3 different patients under standardized dialysis conditions. Blood- and dialysate-side urea clearances were measured at 30 and 150 minutes of treatment. Macroscopic and densitometrical analysis revealed that flow distribution was most homogeneous in the dialyzer with Moiré structure (Type C) and least homogeneous in the standard dialyzer (Type A). Space yarns (Type B) gave an intermediate dialysate flow distribution. Significantly increased urea clearances (p<0.001) were seen with Types B and C, compared to the standard dialyzer. Type C (Moiré) had the highest clearances although these were not significantly greater than Type B (space yarns). In conclusion, more homogeneous dialysate flow distribution and improved small solute clearances can be achieved by use of spacing yarns or waved (Moiré structure) patterns of fiber packing in the dialyzer. These effects are achieved probably as a result of reduced dialysate channeling resulting in a lower degree of mismatch between blood and dialysate flows. The new radiological technique using the helical CT scanner allows detailed flow distribution analysis and has the potential for testing future modifications to dialyzer design.

Equipment Design↗
PubMed2000

[Evolution of the technique and indications of mini-invasive surgery of cholelithiasis].

BACKGROUND: A review of the experience with laparoscopic cholecystectomy to evaluate the impact of the efficacy, safety, and complications on the learning curve. STUDY DESIGN: Retrospective study. METHODS: Between 1993 and 1998, 415 patients, 123 males and 292 females, median age 52.1 years (range 23-96 years), with symptomatic cholelithiasis, underwent laparoscopic cholecystectomy. On the basis of different selection criteria and surgical techniques adopted, our experience was divided into two periods (93-95 and 96-98). RESULTS: The success rate was 89.4% (371 patients) with a conversion rate of 10.6% (44 patients). Overall complications rate was 2.9% (12 patients): 7 major complications (2 biliary tract injuries, 2 hemorrhages, 1 sub-phrenic abscess, 1 gastric perforation and 1 choleperitoneum) and 3 minor complications (1 biliary leakage and 2 wound infections) with 2 long-term sequela (umbilical site eventration). Median hospital stay was 3.3 days, 2.2 days for uncomplicated cases and 5.6 in those converted or complicated. Comparison between the two groups showed a conversion rate of 10.6 vs 10.4% (23 vs 21 patients), with a complication rate of 4.2% vs 2.2%. CONCLUSIONS: Laparoscopic cholecystectomy can be considered a safe and effective procedure for the treatment of simple or complicated cholelithiasis. French surgical technique seems to be easier in the management of acute cholecystitis or lithiasis occurring after acute pancreatitis. Specific training in laparoscopy surgery is mandatory to avoid major complications.

Adult↗
PubMed1999

Feasibility of a porto-intracaval shunt for liver total vascular exclusion in the rabbit: preliminary report.

The animals do not tolerate prolonged caval and/or portal clamping which induces negative pathophysiological events such as release of kinins, damage of the intestinal mucosa, and bacterial translocation. In human liver surgery, these problems have been solved by bio-pump for veno-venous bypass. In order to find a simple method to reproduce a veno-venous bypass, we developed the porto-intracaval shunt and used it in six adult rabbits. The shunt tested was a self constructed 7-french polyurethane shunt modeled as an inverted Y. The inferior vena cava vein below the diaphragm and below the liver and the portal vein were gently dissected. The two longer branches of the shunt were inserted in the cava vein, while the remaining branch of the Y shunt was inserted in the portal vein. After clamping the hepatic artery, the liver was partially resected in three animals and after 60 min the shunt was removed. The insertion of the shunt was always easy and the animals tolerated well the procedure and the anhepatic phase. Our study has been performed in order to test especially the technical feasibility of this shunt in an effort to reduce portal and caval stasis during the anhepatic phase of the surgical procedures that require caval and portal clamping. The technical feasibility has been obtained but we believe that the materials and dimensions of the shunt have to be perfected and adapted depending on the size of the cava and portal veins.

Animals↗
PubMed1999

Present and future options in continuous renal replacement therapies of sepsis and MOF.

Conventional continuous extracorporeal treatments such as hemofiltration and hemodiafiltration have not achieved significant reduction in cytokine plasma levels, in spite of their increasing popularity mainly related to the unnecessary fluid restriction thereby rendering adequate caloric intake possible (Actualités Nephrologiques, 1994). This is mainly due to reduced filtration, to saturability of the adsorption-related phenomena and to the absence of a convective mass transfer. New approaches have been more recently introduced. The concept of blood purification has been applied in some new innovative techniques that use non-selective or selective sorbents. We will focus on the criteria used by others and us to assess the efficiency in vitro and in animal models of sepsis of more recently introduced non-selective and selective devices. Among the innovative techniques, modalities aimed at the plasma treatment will receive emphasis. These modalities that are based on plasma filtration with the use of different sorbents. The preliminary results obtained from ongoing clinical trials will be presented. We will also expand on the technical, biological and clinical aspects that should be addressed in order to establish a new modality as innovative in the treatment of sepsis.

Hemofiltration↗
PubMed1999

In vitro and in vivo evaluation of a new polysulfone membrane for hemodialysis. Reference methodology and clinical results. (Part 1: in vitro study).

Different high flux membranes have been recently developed. The present study is aimed at describing the technical features and the clinical performances of a new high flux polysulfone membrane (T-sulfone, Toray, Japan). The study has been carried out on two different dialyzers (surface area = 1.3 and 1.8 m2). The filters have been tested in vitro under definite experimental conditions. The hydraulic flow resistance, the pressure drop in the blood compartment and the hydraulic permeability have been determined in a wide range of in vitro experimental conditions. The in vitro sieving coefficients for various solutes have also been determined utilizing human blood. Hydraulic permeability was found in the range of 28.4 ml/h/mm Hg/m2 and sieving coefficients were between 0.96 and 1.0 for all low molecular weight solutes. The sieving coefficient for inulin was 0.95. The pressure drop in the filter at 300 ml/min of blood flow was 95 mm Hg for the 1.3 m2 and 57 mm Hg for the 1.8 m2. The filters are then designed to operate in the presence of high blood flows without excessive resistance in the blood compartment. The blood compartment analyzed by means of a special radiological sequence obtained with a helical scanner after dye injection confirmed the homogeneous distribution of the blood flow in several cross sections of the bundle. Adequate distribution of dialysate was confirmed with a similar method applied to the dialysate compartment. The new imaging techniques utilized were greatly helpful to determine adequacy of filter design and flows distribution.

Biocompatible Materials↗
PubMed1999

In vitro and in vivo evaluation of a new polysulfone membrane for hemodialysis. Reference methodology and clinical results. (Part. 2: in vivo study).

Different high flux membranes have been recently developed. The present study is aimed at describing the technical features and the clinical performances of a new high flux polysulfone membrane (T-sulfone, Toray, Japan). The study has been carried out on two different dialyzers (surface area = 1.3 and 1.8 m2). The filters have been tested in vivo during hemodialysis and hemodiafiltration. The in vivo study was carried out on 12 ESRD patients on regular hemodialysis treatment. The protocol was reviewed and approved by the local ethical committee. The in vivo clearances (K) at 300 ml/min of blood flow are reported in the following Table: [Table in text]. Beta-2-m reduction ratio exceeded 50% in all sessions. Beta-2-m mass balance executed by collection of spent dialysate and elution from the used filters evidenced that removal is obtained mostly by filtration while absorption is negligible. Excellent tolerance and hemocompatibility was observed in all the studied sessions.

Adsorption↗
PubMed1999

Use of adsorptive mechanisms in continuous renal replacement therapies in the critically ill.

The pathophysiology of sepsis is becoming a more complicated scenario. In sepsis, endotoxin or other gram-positive derived products induce a complex and dynamic cellular response giving rise to several mediators known to be relevant in the pathogenesis of septic shock, such as specific mediators. substances responsible for up- or down-regulation of cytokine receptors and cytokine antagonists, inactivators of nuclear factor-kappaB or signal transduction pathways, and precursor molecules. In this article, we delve into some new concepts stemming from the use of sorbents in continuous plasma filtration. The rationale is based on the assumption that the nonspecific removal of several mediators of the inflammatory cascade and cytokine network may improve outcome in a rabbit model of septic shock and hemodynamics in a pilot clinical study. The importance of looking for innovative treatments specifically targeted for the special needs of the critically ill patients rather than using concepts and technology applied to the treatment of chronic renal failure is underlined.

Animals↗
PubMed1999

[Kidney and urinary tract injuries. Experience with 113 cases].

BACKGROUND: Trauma of the kidney and urinary tract is not rare in emergency surgery and the related treatment needs today high competence and interdisciplinary approach. Aim of the study was to analyze the personal experience in order to find differences in the treatment during the last years especially for trauma of the kidney. METHODS: The authors report 113 cases of kidney or urinary tract trauma out of 16,569 patients admitted in emergency between 1981 and 1995. Fifty patients (44%) underwent surgery. Thirty patients (26%) underwent surgery for kidney trauma but in only 5 (16%) conservative surgery for partial damage was possible. Section of the ureter occurred in one patient. Ten patients had a rupture of the bladder and 9 the rupture of urethra. The cause of trauma was a gunshot wound in 11 patients (22%). Nineteen patients (38%) had also damage to other organs. RESULTS: The results show absence of morbidity or mortality related with urinary tract trauma. CONCLUSIONS: The analysis of these cases shows that the improvement of diagnostic possibilities allowed the reduction of surgical interventions especially for kidney trauma.

Adolescent↗
PubMed1998

Experimental models in microsurgery.

The development of experimental microsurgery can be considered the natural evolution of a diffuse need to increase precision in many fields of surgery. Microsurgery accelerated the possibility of deepening many unclear aspects of pathophysiology, using miniaturized and reproducible experimental models. We report briefly on the fundamental principles of microsurgery and the most frequently performed and useful models of experimental microsurgery, especially to employ as training models for surgeons, but also as bases for developing new and always-welcome models.

Disease Models, Animal↗