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Biomedical subjects

A Lupi

Publications and source records attributed to A Lupi.

At least 55 records · Page 3Linked to original sources
PubMed1996

Bovine hemoglobin cross-linked through the beta chains: functional and structural aspects.

2-Nor-2-formylpyridoxal (NFPLP) has been synthesized and coupled to bovine Hb according to the procedure developed by Benesch and Benesch. The reaction of bovine Hb with NFPLP leads to a cross-linkage between the beta subunits, which greatly stabilizes the low affinity T state of the molecule and simultaneously abolishes the tendency of the tetramer to dissociate into alpha beta dimers. The functional properties, examined from both the equilibrium and kinetic points of view, indicate that the chemical modification affects the O2 affinity, abolishes cooperativity, and induces a slight decrease of the Bohr effect. From modeling studies we are confronted with two different structural alternatives; the cross-link of beta chains may be formed between lysine 82 of beta2 and the N terminus of methionine 2 of beta1 or between the two lysine 82 residues of both beta2 chains. Digestion of modified beta globin chains and isolation of the cross-linked peptide have showed that NFPLP cross-links Met-beta2 and Lys-beta82. This allowed discussion in some detail of the molecular basis of the Bohr effect of the modified bovine hemoglobin. On the whole, NFPLP-modified bovine Hb could be considered as a first step toward the synthesis of a potential blood substitute.

Animals↗
PubMed1995

Removal of platelet-activating factor in experimental continuous arteriovenous hemofiltration.

OBJECTIVE: There is a positive correlation between the amount of ultrafiltration and the improved survival rate of patients with ischemia or sepsis-induced acute renal failure. Continuous arteriovenous hemofiltration (CAVH) removes vasoactive substances with a molecular weight of < 1000 daltons. This study evaluated the removal of platelet-activating factor, a lipid mediator of endotoxic shock, by CAVH with respect to kinetics, adsorption, and ultrafiltration. DESIGN: Prospective laboratory study. SUBJECTS: Normal human subjects. INTERVENTIONS: Radioactive [3H] or biologically active platelet-activating factor was added to whole blood or washed blood resuspended in Tris-buffered (pH 7.2) physiologic saline with 4% human serum albumin or plasma. Whole or washed blood cells or plasma were recirculated at 100 mL/min through polysulfone hemofilters for 120 mins with ultrafiltration (condition A), without ultrafiltration (condition B), or in a static condition (condition C). Concentrations of albumin, total protein, and radioactive or biologically active platelet-activating factor in samples obtained from the blood and ultrafiltrate compartment were determined. MEASUREMENTS: Biologically active platelet-activating factor was quantified on washed rabbit platelets and results were expressed in ng/mL over a calibration curve obtained with synthetic platelet-activating factor. MAIN RESULTS: [3H]-platelet-activating factor added to recirculated whole blood was ultrafiltered (percent of ultrafiltered platelet-activating factor/min: 0.48 +/- 0.02 [SD]; total platelet-activating factor removed in 120 mins: 15.52%; condition A) at significantly (p < .001) higher amounts than when added to washed blood cells (percent of ultrafiltered platelet-activating factor removed/min: 0.195 +/- 0.06; total platelet-activating factor removed in 120 mins: 7.46%). The highest amounts of [3H]-platelet-activating factor were bound to polysulfone membranes after recirculation with whole blood (44.5 +/- 12.2%) than with washed blood (1.1 +/- 0.3%) or plasma (11.9 +/- 0.7%). Biologically active platelet-activating factor concentrations significantly decreased in both conditions A and B (maximal decrease at 120 mins: 63% and 59%, respectively). No significant reduction could be observed in condition C. CONCLUSIONS: These studies provide experimental evidence for the prompt, efficient removal of platelet-activating factor in CAVH and provide a possible rationale for the beneficial effect of this therapy in the development of multiple organ failure in sepsis.

Adsorption↗
PubMed1995

Differences in vasodilatory response to dipyridamole between patients with angina and normal coronary arteries and patients with successful coronary angioplasty.

BACKGROUND: Previous studies reported a reduced coronary blood flow reserve, assessed by the intravenous administration of dipyridamole, in patients with angina and normal coronary arteries, and early after successful coronary angioplasty, which suggests the presence of small coronary vessel dysfunction. This study aimed to establish whether the mechanisms of small coronary vessel disease in these two groups of patients are similar. METHODS: The effects of the intracoronary infusion of adenosine and dipyridamole (maximum dose 2.7 and 7.5 mg/min, respectively) on coronary blood flow velocity were assessed in 11 patients with angina and normal coronary arteries (group A) and in 12 patients immediately after successful coronary angioplasty (group B) using a 0.018" Doppler wire. RESULTS: Baseline coronary blood flow velocity was significantly higher in group B than group A (34 +/- 14 versus 19 +/- 8 cm/s; P = 0.001). In group A, coronary blood flow velocity was higher during adenosine than dipyridamole infusion (74 +/- 17 versus 58 +/- 21 cm/s; P < 0.001), whereas in group B velocities were similar (85 +/- 30 versus 78 +/- 32 cm/s; NS). CONCLUSIONS: In patients with angina and normal coronary arteries, a maximal dose of adenosine causes a greater coronary dilation than that of dipyridamole. Given that dipyridamole operates mainly through an inhibition of adenosine re-uptake, it can only dilate the arteriolar segments exposed to endogenous adenosine. Therefore, the lower response to dipyridamole than to exogenous adenosine observed in patients with angina and normal coronary arteries suggests an impairment of the pre-arterioles that are not influenced by endogenous adenosine, resulting in a limited flow-mediated dilation in response to arteriolar dilation. Such an impairment is not apparent immediately after successful coronary angioplasty, where the most obvious abnormality is an increase of baseline coronary blood flow velocity.

Adenosine↗
PubMed1995

[The Shouldice plastic surgery: our clinical experience].

The Authors present cases of groin hernioplasty using the Shouldice method; the method used for more than six years, such as elective technique to treat groin hernia, is evaluated on the basis of results of complications and recurrences. A careful clinical check of patients operated on over one year at least, allows confirmation of the efficiency of the method, because it results in a low percentage of recurrence and complications, plus a low social and economical cost. For these reasons it is proposed that the method is applied in day surgery.

Adult↗
PubMed1994

[Pulmonary carcinoid tumors].

27 patients suffering from carcinoid of the lung (18 females and 9 males, middle age 52 years, range 26-68) underwent surgery in our department. The neoplasms were located at the pulmonary hilum in 21 cases. The diagnosis was occasional in 6 cases, cough (51.8%) and recurrent bronchitis (37%) were the most frequent symptoms. No instances of carcinoid syndrome were detected. Preoperative staging ruled out pathologic mediastinal lymph nodes or hematogenous metastases. 26 patients underwent complete excision of the neoplasm (11 lobectomies, 9 pneumonectomies, 4 bilobectomies, 1 segmental resection, 1 bronchial wedge resection). Histologically, 4 cases were categorized as atypical carcinoids. Two patients died within 1 year, one suffering from atypical carcinoid because of disease progression, and an other one (suffering from atypical carcinoid) who underwent only at exploratory thoracotomy followed by chemotherapy. A patient suffering from typical carcinoid died within 1.5 years because of gallbladder carcinoma. From our experience and from the literature review it appears that carcinoids has to be considered as malignant neoplasms and treated according to.

Adult↗
PubMed1994

[Iatrogenic rupture of the esophagus: presentation of several cases].

Four cases of iatrogenic rupture of the oesophagus are presented. The site of the lesion was in the cervical tract in 1 case and in the thoracic tract in the other 3 cases. Their etiology was pneumatic endoscopic dilatation for achalasia in 2 cases, endoscopic insertion of a Celestin tube for carcinoma of the thoracic tract of the oesophagus in 1 case, and diagnostic endoscopy in the last one. Instrumental findings were relevant in all cases. All patients underwent surgery. In the patients suffering from achalasia, the rupture was repaired by a patch of the gastric fundus. The patient suffering from carcinoma underwent an oesophageal resection, the one with cervical perforation underwent a mediastinal drainage. There were no deaths or considerable post operating complications. In a patient suffering from achalasia gastro-oesophageal reflux was demonstrated after some months following the operation.

Aged↗
PubMed1994

[Primary germinal tumors of the mediastinum: our experience in 9 cases].

9 patients (8 males 1 female, middle age 24.3 years, range 20-41) affected by primary mediastinal germ cell tumor were surgically treated in our department. They were 4 seminomas, 2 embryonal carcinomas, 1 malignant teratoma and 2 benign teratomas. Three patients were asymptomatic; cough, dyspnea and chest pain were the most frequently observed symptoms. The staging work-up did not show signs of metastatic disease in the malignant types. Benign teratomas underwent complete excision. In one patient suffering from seminoma radiotherapy and chemotherapy caused complete remission of the disease. In the others cases remission of the neoplasm was obtained by resection and adjuvant therapy in 3 cases, by neoadjuvant treatment and excision of the residual mass in 3 cases. Among the patients suffering from seminoma, 2 are dead at 60 months since initial treatment and 2 are alive at 132 and 120 months respectively. Among the patients with malignant nonseminomatous tumours, 2 are alive at 60 and 36 months and 1 patient is dead at 13 months. Two patients with benign teratoma are alive at 189 and 168 months respectively. At present a multimodality treatment including surgery, radiotherapy and cisplatin-based combination chemotherapy, give the most satisfactory results in the treatment of malignant mediastinal germ cell tumours.

Adolescent↗
PubMed1993

Value and limits of testicular scintigraphy in paediatric acute scrotum.

Abrupt onset of scrotal symptoms is a not uncommon condition, particularly in the paediatric age, which raises the problem of a rapid decision concerning proper therapeutic management (i.e. surgery or pharmacotherapy); the testicular radionuclide scan is generally considered to be helpful in making this choice, as it is theoretically able to distinguish between hypervascular (inflammation) and hypovascular conditions (testicular torsion). We report our experience in paediatric patients presenting acute scrotum. Thirty consecutive cases were examined, but three were discarded because of their non-routine features. Our records show that torsion of the appendix testis is far from uncommon (6 cases out of 27); however, the scintigraphic pattern of this pathological condition, which usually does not require urgent surgical treatment, does not seem to differ greatly from that of scrotal inflammation. Of the remaining 21 cases, 15 were correctly diagnosed, while 4 were to be considered non-diagnostic because of the presence of hypovascular scrotal conditions other than testicular torsion. We conclude that, while not always a very precise tool for the diagnosis of acute scrotum, nevertheless testicular scan results may be considered a useful parameter in choosing the proper type of treatment.

Adolescent↗
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↗
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↗
PubMed1977

Synthetic analogs of natural prenylated and chromene chalcones.

A number of synthetic analogs of the prenylated and chromene chalcones isolated from lonchocarpus neuroscapha (Leguminosae) were obtained by condensation of prenylated acetophenones with substituted benzaldehydes. The antibacterial activity of these products was studied and correlated with their structure.

Acetophenones↗