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Biomedical subjects

A Zonta

Publications and source records attributed to A Zonta.

At least 19 recordsLinked to original sources
PubMed2004

How to study boron biodistribution in liver metastases from colorectal cancer.

The purpose of this study was to evaluate boron distribution for a safe and effective BNCT (Boron Neutron Capture Therapy) of liver metastases. Samples both from healthy and tumour liver parenchyma were analysed, after i.v. boron administration, by: alpha particles counting under neutron irradiation; morphological analysis by standard haematoxylin-eosin staining; neutron autoradiography. Our method was unaffected by the cytological heterogeneity inside tumour nodules; it demonstrated selective boron distribution in tumour tissue and predicted estimated mean therapeutic doses in tumour and safety doses in healthy tissue. The time interval for efficient BNCT was 2 to 4 hours after i.v. boron administration.

Animals↗
PubMed2003

[Experimental kidney transplantation: a comparison between different models].

AIM: Two different models of kidney transplantation have been compared using 3 different techniques. The kidney grafts were procured from living donors (laparoscopic or laparotomic technique) and from cadaveric donors. METHODS: Twenty-four outbred piglets (Large White, weight range 24-27 kg) underwent kidney transplantation. We divided the recipients into 2 groups with the following characteristics: group 1 (n=12) was represented by orthopic kidney recipients whose grafts were retrieved by laparoscopic or lapartomic technique from living unrelated donors; group 2 (n=12) was constituted by heterotopic kidney recipients whose grafts were retrieved by laparotomic technique from unrelated cadaveric donors. In both groups, Grogoire-Lich technique and Politano-Laedbetter technique were used in order to perform ureteral-vescical anastomosis together with a new technique developed from our experience called Politano-Laedbetter modified. All transplanted pigs underwent double immunosoppressive steroid therapy (tacrolimus and micofenolate mofetil). The pigs were observed for 60 days. RESULTS: The survival rates in group 1 and in group 2 were 75% (n=9) and 66% (n=8), respectively. No significative differences were noted in length of operative time, creatinemia and ureamia levels in both study groups. The Gregoire-Lich technique was associated with a higher rate of complications. CONCLUSION: Two different experimental models of kidney transplantation are feasible in pigs. The classic technique could be combined with the orthopic one based on the type of study needed.

Animals↗
PubMed2000

Directed evolution of an enantioselective lipase.

BACKGROUND: The biocatalytic production of enantiopure compounds is of steadily increasing importance to the chemical and biotechnological industry. In most cases, however, it is impossible to identify an enzyme that possesses the desired enantioselectivity. Therefore, there is a strong need to create by molecular biological methods novel enzymes which display high enantioselectivity. RESULTS: A bacterial lipase from Pseudomonas aeruginosa (PAL) was evolved to catalyze with high enantioselectivity the hydrolysis of the chiral model substrate 2-methyldecanoic acid p-nitrophenyl ester. Successive rounds of random mutagenesis by ep-PCR and saturation mutagenesis resulted in an increase in enantioselectivity from E=1.1 for the wild-type enzyme to E=25.8 for the best variant which carried five amino acid substitutions. The recently solved three-dimensional structure of PAL allowed us to analyze the structural consequences of these substitutions. CONCLUSIONS: A highly enantioselective lipase was created by increasing the flexibility of distinct loops of the enzyme. Our results demonstrate that enantioselective enzymes can be created by directed evolution, thereby opening up a large area of novel applications in biotechnology.

Amino Acid Sequence↗
PubMed1999

Liver ischemia modifies the concentration of plasmatic catecholamines after reperfusion in the rat.

Pulmonary hypertension is one of the most frequent and severe consequences of liver ischemia. The aim of this study is to evaluate the presence of humoral vasoactive mediators, generated during liver ischemia, which could be able to determine the onset of pulmonary hypertension. Thus, we evaluated the plasmatic concentration of catecholamines (adrenaline, noradrenaline, dopamine) during the immediate reperfusion period. Wistar rats were used. Animals (n = 89) were divided into four groups. Group 1 served as control (sham-operated). In group 2 animals underwent 60 min of left hepatic exclusion. In group 3 animals underwent to bilateral adrenectomy. In group 4 animals had both bilateral adrenectomy and liver ischemia. Ischemia in group 2 and 4 was induced by interrupting the vascular supply to the left and median lobes, so avoiding the use of a portal shunt. Blood samples were collected from the suprahepatic inferior caval vein immediately after reperfusion. Strips of the main pulmonary artery were put into an isolated organ bath and tested for the response to noradrenaline, adrenaline and plasma samples. Plasma samples collected after ischemia caused a significantly greater (p < 0.01) contraction of the pulmonary artery compared to controls. Plasma samples collected after adrenectomy caused a weak contraction which was not different from that obtained in the adrenectomy + ischemia group. Plasma concentrations of catecholamines after liver ischemia were significantly increased in the control group (p < 0. 01). In adrenectomized rats only the adrenaline level was greatly reduced. However ischemia did not increase plasma catecholamines as it occurred in sham-operated rats.

Animals↗
PubMed1999

[Whole pancreatic transplantation and islet transplantation. Experiment notes].

BACKGROUND: The results of pancreas transplantation have greatly improved in recent years. The path to further improvements goes through extensive experimental researches. METHODS: This study describes the effects of different procedures as hemodynamic asset and postoperative outcome. Twenty-nine swine underwent a total pancreatectomy, and were stratified into five groups. Group one (n = 5) served as control. Group two (n = 7) was autotransplanted. Group three (n = 6) and group four (n = 6) underwent allotransplantation; the first without immunosuppression and the second treated with cyclosporine and steroids. In group five (n = 5) Langerhans Islets transplantation was performed. RESULTS: Survival was different depending on which methodology was applied. The postoperative survival was 7 +/- 2 days in group one, 24 +/- 16 days in group two, 17 +/- 7 days in group three, 27 +/- 8 days in group four and 12 +/- 6 days in group five. CONCLUSIONS: The postoperative glucose control was normal in group two and group four while a severe diabetes appeared in group one (group 1 vs group 2: p < 0.05) and in group three during acute graft rejection after the 12th postoperative day (group 3 vs group 4: p < 0.05). Glycemia was slightly controlled in group five. The intraoperative hemodynamic status was evaluated at the time of pancreatectomy, harvesting, revascularization, and when surgery was over. Among the different parameters studied (mean arterial and pulmonary pressure, pulmonary wedge pressure, central venous pressure, cardiac output, oxygen extraction ratio, systemic vascular resistance, oxygen delivery and oxygen consumption), a statistically significant difference between group one and group five (p < 0.05) was observed.

Animals↗
PubMed1998

Radioimmunoassisted surgery for lung metastases from colorectal cancer: results and perspectives.

The high incidence of resectable lung metastases from colorectal cancer and the very poor prognosis of untreated patients (less than 24-month survival) has promoted the surgical approach to treatment. Since the main aims of this kind of surgery are the complete resection of the tumor, the preservation of tumor-free parenchyma, and a minimal surgical trauma, innovative surgical techniques have been developed. We report on our experience in the radioimmunoassisted pulmonary metastasectomy by the use of a hand-held gamma-detecting probe (GDP) and describe the application of the intraoperative radioimmunolocalization of tumor to video-assisted minimally invasive surgery.

Antibodies, Monoclonal↗
PubMed1998

Internal mammary blood supply for ileo-colon interposition in esophagogastroplasty: a case report.

We report on a clinical case where microsurgical techniques successfully supported traditional surgery in a wide reconstruction between the oropharynx and small bowel. Several years ago, the patient sustained a severe corrosive injury of the upper digestive tract with subsequent esophageal stricture and stiffening; at that time, an emergency gastrectomy was performed. In this case, the restoration of the defect could not rely on the classic colonic interposition. During the operation the ileo-colic flap, well-fitted for tension-free reconstruction, revealed the foreseen inadequacy of its vascularization based on the sole middle colic vascular pedicle. The blood supply to its proximal part was then increased by microanastomosis between the right internal mammary and ileo-colic vessels. The revascularization ensured the viability of the interposed tissue. Oral intake resumed after 3 weeks; nowadays the patient is able to maintain her ideal weight with adequate nutrition.

Adult↗
PubMed1998

[Treatment of the nephrotoxicity of immunosuppressive drugs with insulin-like growth factor-I].

BACKGROUND: Delayed graft function is a common and severe complication after cadaveric kidney transplantation. Besides a more complicated postoperative course, DGF can worsen the overall graft survival. In particular, DGF enhances the nephrotoxicity of mainstream immunosuppressants cyclosporine and FK506. This study evaluates a new therapeutical approach to the treatment of DGF related nephrotoxicity, based on the administration of IGF-I. METHODS: Sixty inbred Lewis rats underwent a bilateral clamping of the renal pedicles (20') as standard damage. The animals were stratified in six groups, according to the postoperative treatment. Group 1 served as control and received only the standard ischemic injury. Cyclosporine and FK506 were added in groups 3 and 5. Groups 2, 4 and 6 had the same treatment of groups 1, 3, 5 respectively, plus the administration of IGF-I. Blood samples were drawn daily to evaluate creatinine and BUN for 7 days. RESULTS: The rats treated with IGF-I had significantly better values compared to the respective controls (2-way ANOVA, p < 0.05). CONCLUSIONS: In conclusion, IGF-I improves the nephrotoxicity of mainstream immunosuppressants in this model. Its use is potentially beneficial for transplantation.

Animals↗
PubMed1998

[Duodenal schwannoma. Clinical considerations].

The recent observation of a case of schwannoma in the second part of the duodenum lead the authors to a literature survey in order to state the present knowledge of this subject. Schwannoma is an ectodermal neoplasm arising from the nerve sheath that envelop axons. In the gastrointestinal tract these tumours can concern cells of the myentericus and submucosus plexus of the intestinal wall. A duodenal location is extremely rare. Gastroduodenal endoscopy, abdominal ultrasonography and CT scan were found as important investigatory tools, but only histological examination of the excised tissue suggests the definitive diagnosis. Therapy consists in the radical excision of the tumour; this is rarely obtained by endoscopic way because of the submucosal neoplastic growth. Then a surgical laparotomic approach is more often required and it allows to perform local excisions through a duodenotomy, partial duodenectomy or ampullectomy and more complex operations, like a cephalic duodenopancreatectomy, in front of extended papillar involvement. The latter was the suitable treatment for radical removing of the juxtapapillar schwannoma reported by the authors; the uneventful postoperative course, the patient's excellent general conditions and nutriture at 12 months confirm the validity of the therapeutic policy.

Duodenal Neoplasms↗
PubMed1998

[The hemodynamic effects of the in-vivo administration of insulin-like growth-factor I].

BACKGROUND: Recent studies have demonstrated that IGF-I has several biological activities that correlate with the GH axis, by acting as a cell protecting factor and a promoting compound in different tissues and organs. Our latest findings have demonstrated a potential application of IGF-I in the treatment of postischemic renal injury, which frequently appears after a kidney transplant. The beneficial effect of the renal postoperative recovery probably correlates with the regulation of the vascular tone, in which IGF-I plays a role with other cytokines. However, this rises the question whether IGF-I has any effect on the general hemodynamic status. This study was designed to underline the intraoperative hemodynamic effect of exogenous IGF-I in an experimental setting of renal transplantation in swine. METHODS: Twelve female swine underwent a left renal autotransplantation. At the reperfusion the animals were separated in two groups. Group one served as control. Group two received 400 micrograms of IGF-I (added to the flushing solution). The animals were kept under complete hemodynamic monitoring over the operation. RESULTS: Among the different parameters studied (mean arterial pressure, mean pulmonary arterial pressure, pulmonary wedge pressure, central venous pressure, cardiac output, oxygen extraction ratio, systemic vascular resistance, oxygen delivery and oxygen consumption), any statistically significant difference between group one and two were observed. CONCLUSIONS: While the clinical administration of IGF-I requires further studies, the in vivo administration of this peptide is apparently well tolerated, and does not cause any hemodynamic instability to the operation.

Analysis of Variance↗
PubMed1997

Insulin-like growth factor-I ameliorates delayed kidney graft function and the acute nephrotoxic effects of cyclosporine.

BACKGROUND: Delayed graft function (DGF) is a relatively common complication after cadaveric renal transplantation. The adverse effect of DGF on long-term graft survival has lead to intensive efforts to reduce ischemic graft injury. In this study we examined the effects of a new protective treatment based on insulin growth factor (IGF)-I. We evaluated the impact of the treatment on renal recovery and on the nephrotoxicity that is a common side effect of mainstream immunosuppressants. Because therapy with IGF-I or the analog des(1-3)IGF-I is effective in treating experimental ischemic renal failure, these peptides may be useful as perspective clinical treatments. METHODS: We have addressed three areas relating to the potential use of IGF-I and its analog des(1-3)IGF-I. First, because of the immunogenic properties of IGF-I, we assessed the effect of des(1-3)IGF-I on the rejection of skin allografts in Lewis rats. Next we determined whether treatment with des(1-3)IGF-I influences the early function of transplanted kidneys in a model of DGF induced by a combination of warm and cold ischemia. Finally we tested whether IGF-I protects against acute cyclosporine nephrotoxicity. RESULTS: Des(1-3)IGF-I did not accelerate the rejection of the skin grafts (P=0.57). The administration of this peptide in a model of syngenic renal transplant improved the early function of the graft. Postoperative values of creatinine and blood urea nitrogen were significantly better (P<0.05) in treated animals. IGF-I also ameliorated the nephrotoxicity of cyclosporine, with better values of creatinine and blood urea nitrogen (P<0.05). CONCLUSIONS: In evaluating this study it should be recognized that the animal models studied, although widely used, differ from the human condition. However, IGF-I and des(1-3)IGF-I exhibit properties that strongly suggest their value in preventing clinical DGF, and they deserve further studies.

Animals↗