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Biomedical subjects

F Piazza

Publications and source records attributed to F Piazza.

At least 55 records · Page 3Linked to original sources
PubMed1998

Involvement of the IP-10 chemokine in sarcoid granulomatous reactions.

The accumulation of T cells and monocytes at sites of ongoing inflammation represents the earliest step in the series of events that lead to granuloma formation in sarcoidosis. In this study, we evaluated the pulmonary production of IFN-inducible protein 10 (IP-10), a CXC chemokine that stimulates the directional migration of activated T cells. Striking levels of IP-10 were demonstrated in the bronchoalveolar lavage (BAL) fluid of 24 patients with pulmonary sarcoidosis and lymphocytic alveolitis, as compared with patients with inactive disease or control subjects. A positive correlation was demonstrated between IP-10 levels and the number of sarcoid CD45R0+/CD4+ cells in the BAL. Immunochemistry, performed with an anti-human IP-10 polyclonal Ab in lymph nodes displaying prominent sarcoid granulomas, showed that cells bearing IP-10 were mainly epithelioid cells and CD68+ macrophages located inside granulomatous areas. Macrophages recovered from the BAL of sarcoid patients stained positive for IP-10 protein. Furthermore, alveolar macrophages isolated from sarcoid patients with T cell alveolitis and cultured for 24 h in presence of IFN-gamma secreted definite levels of IP-10 capable of inducing T cell chemiotaxis. Interestingly, alveolar lymphocytes recovered from patients with active sarcoidosis were CD4+ T cells expressing Th1 cytokines (IL-2 and IFN-gamma) and high levels of CXCR3. Taken together, these data suggest the potential role of IP-10 in regulating the migration and activation of T cells toward sites of sarcoid inflammatory process and the consequent granuloma formation.

Adult↗
PubMed1998

Development of a chemiluminescent urease activity assay for Helicobacter pylori infection diagnosis in gastric mucosa biopsies.

A chemiluminescent urease activity assay has been developed and optimized using the chemiluminescent pH indicator phthalhydrazidylazoacetylacetone. This compound is stable at pH </= 7 and decomposes at higher pH values, emitting light in the presence of H2O2. Urease catalyzes hydrolysis of urea to form NH3 and CO2 which increase the pH of the reaction medium, thus allowing the chemiluminescent indicator to decompose and produce photons. The emitted light is proportional to the urease activity when urea is in excess. Urease tests based on colorimetric pH indicators like phenol red are commercially available and commonly used for the rapid diagnosis of Helicobacter pylori infection in gastric mucosa biopsy specimens, since this bacterium produces high amounts of urease. Such colorimetric tests often lack sensitivity, giving false-negative results. The developed chemiluminescent test proved to be at least 50-fold more sensitive than the colorimetric tests, permitting early diagnosis of infection, and it is more rapid, giving results in 1-10 min compared to 30 min. Further applications of this assay could be the in situ localization of urease activity, corresponding to the presence of H. pylori, in gastric mucosa cryosections and the development of high-throughput screening assays of antimicrobial drugs able to inactivate the bacterium.

Adult↗
PubMed1998

Separation techniques for bile salts analysis.

The analysis of bile salts in biological samples has remained a difficult task, due to the complex nature of the salts and also to their low concentration in common sample fluids such as plasma and urine. Given their importance, the development of accurate and sensitive methods of instrumental analysis has been the subject of intensive research, and recent advances have eliminated or lessened some of the difficulties. Currently available techniques are the following: thin-layer chromatography, gas chromatography, high-performance liquid chromatography, supercritical fluid chromatography, gas chromatography-mass spectrometry and capillary electrophoresis. Liquid chromatography coupled with mass spectrometry (thermospray, fast atom bombardment, electrospray and ionspray), a method undergoing continuous improvement, is also being applied to bile salts analysis. In this paper, these various techniques, which differ greatly in specificity, accuracy and simplicity, are reviewed and discussed, in terms of analytical performance, applicability to a given sample fluid, major limitations, ability to identify uncommon bile salts, including unsaturated oxo derivatives, glucuronides, sulfates, glycosides and bile alcohols.

Bile Acids and Salts↗
PubMed1998

Definition of the interferon-alpha receptor-binding domain on the TYK2 kinase.

Interferons and cytokines modulate gene expression via a simple, direct signaling pathway containing receptors, JAK tyrosine kinases, and STAT transcription factors. The interferon-alpha pathway is a model for these cascades. Two receptors, IFNaR1 and IFNaR2, associate exclusively in a constitutive manner with two JAK proteins, TYK2 and JAK1, respectively. Defining the molecular interface between JAK proteins and their receptors is critical to understanding the signaling pathway and may contribute to the development of novel therapeutics. This report defines the IFNaR1 interaction domain on TYK2. In vitro binding studies demonstrate that the amino-terminal half of TYK2, which is approximately 600 amino acids long and contains JAK homology (JH) domains 3-7, comprises the maximal binding domain for IFNaR1. A fragment containing amino acids 171-601 (JH3-6) also binds IFNaR1, but with reduced affinity. Glutathione S-transferase-TYK2 fusion proteins approximating either the JH6 or JH3 domain affinity-precipitate IFNaR1, suggesting that these are major sites of interaction within the larger binding domain. TYK2 amino acids 1-601 act in a dominant manner to inhibit the transcription of an interferon-alpha-dependent reporter gene, presumably by displacing endogenous TYK2 from the receptor. This same fragment inhibits interferon-alpha-dependent tyrosine phosphorylation of TYK2, STAT1, and STAT2.

Binding Sites↗
PubMed1998

Taurohyodeoxycholic acid protects against taurochenodeoxycholic acid-induced cholestasis in the rat.

The prevention of the hepatotoxic effects produced by intravenous infusion of taurochenodeoxycholic acid (TCDCA) by coinfusion with taurohyodeoxycholic acid (THDCA) was evaluated in bile fistula rats; the hepatoprotective effects of the latter were also compared with those of tauroursodeoxycholic acid (TUDCA). Rats infused with TCDCA at a dose of 8 micromol/min/kg showed reduced bile flow and calcium secretion, as well as increased biliary release of alkaline phosphatase (AP) and lactate dehydrogenase (LDH). This was associated with a very low biliary secretion rate of TCDCA (approximately 1 micromol/min/kg). Simultaneous infusion of THDCA or TUDCA at the same dose preserved bile flow and almost totally abolished the pathological leakage of the two enzymes into bile. The effect was slightly more potent for THDCA. The maximum secretion rate of TCDCA increased to the highest value (8 micromol/min/kg) when coinfused with either of the two hepatoprotective bile acids (BA), which were efficiently and completely secreted in the bile, without metabolism. Calcium output was also restored and phospholipid (PL) secretion increased with respect to the control saline infusion. This increase was higher in the THDCA study. These data show that THDCA is highly effective in the prevention of hepatotoxicity induced by intravenous infusion of TCDCA by facilitating its biliary secretion and reducing its hepatic residence time; this was associated with selective stimulation of PL biliary secretion.

Alkaline Phosphatase↗
PubMed1998

Scutumplasty: costal cartilage versus bone paté.

This study was carried out to evaluate the anatomical and hearing results of the reparation of attic defects in closed tympanoplasty. Reparation was carried out in 194 patients by using a costal cartilage allograft, and in 159 patients with a bone pate autograft. The follow-up was from 1 to 5 years. The study was not truly randomized owing to an occasional lack of allogenic costal cartilage. In the group 'costal cartilage' a partial resorption was observed in 5.7% and a complete resorption in 4.7% of the cases. In the group 'bone pate', partial resorption was observed in 5.5% and total resorption in 2.7% of the patients. Satisfactory hearing results were obtained in 86% of the patients of the group 'costal cartilage' and in 82% of the patients of the group 'bone paté'. Both graft materials may be recommended for repairing erosions caused by the cholesteatoma in the wall of the external auditory canal.

Adult↗
PubMed1998

Learning and approximation capabilities of adaptive spline activation function neural networks.

In this paper, we study the theoretical properties of a new kind of artificial neural network, which is able to adapt its activation functions by varying the control points of a Catmull-Rom cubic spline. Most of all, we are interested in generalization capability, and we can show that our architecture presents several advantages. First of all, it can be seen as a sub-optimal realization of the additive spline based model obtained by the reguralization theory. Besides, simulations confirm that the special learning mechanism allows to use in a very effective way the network's free parameters, keeping their total number at lower values than in networks with sigmoidal activation functions. Other notable properties are a shorter training time and a reduced hardware complexity, due to the surplus in the number of neurons.

Journal Article↗
PubMed1998

[Progressive sensorineural hearing loss: neoplastic causes].

Acoustic neuromas represent about 90% of all space-occupying lesions of the cerebellopontine angle and account for approximately 6% of all intracranial tumors. Progressive unilateral sensorineural hearing loss is the most frequent initial symptom occurring in over 90% of patients. A sudden onset of hearing loss occurs in 5%, while 5% of cases present with normal hearing. The incidence of hearing loss does not seem to be related to tumor size. Accuracy of the tumor detection by gadolinium-enhanced magnetic resonance imaging has been reported as 99-100% even for intracanalicular tumors. The ABR false negative rate for intracanalicular tumors has been reported to be as high as 9-11%. Rare lesions of the cerebellopontine angle include: meningiomas, epidermoids, arachnoid cysts, trigeminal nerve neuromas, facial nerve neuromas, neurinomas of lower cranial nerves, glomus tumors and metastases. Therefore, a high suspicion index and awareness of symptoms and an adequate audiologic and neuroradiologic work-up are the clues to early diagnosis and appropriate surgical treatment.

Cerebellar Neoplasms↗
PubMed1998

[Cleft palate and dysfunction of the eustachian tube].

Secretory otitis media (SOM) is a frequent complication in infants with cleft palate. In cleft palate the muscles that open the Eustachian tube (tensor palatini and levator palatini) have abnormal connections thereby making the tube opening either difficult or impossible. This will lead to secretory otitis media in 95% of cases, since the middle ear will not be aerated. In this paper, 14 patients operated on for cleft palate during the first year of life were examined. SOM was treated only by medical therapy without the insertion of tympanostomy tubes. Post-operative follow-up ranged from 2 months to 5 years. In all patient SOM was still present at last follow-up with poor efficacy of medical therapy. Therefore, our therapeutic protocol includes myringotomy and insertion of tympanostomy tubes during the first general anesthesia for cleft palate treatment.

Adolescent↗
PubMed1998

[Conservative treatment of locally advanced bladder carcinoma: neoadjuvant chemotherapy, TUR and radiotherapy. Results in 40 patients].

PURPOSE: to assess the results of bladder preservation in infiltrating bladder cancer. The potential for neoadjuvant chemotherapy followed by extensive TUR and radiotherapy was investigated in 40 patients with T2-T4a G2-G3 bladder carcinoma. MATERIALS AND METHODS: from 1983 to 1995, 40 patients were submitted to bladder-sparing treatment consisting of neoadjuvant chemotherapy, extensive, TUR and radiotherapy. Most patients had T3G3 cancer. Cystectomy was not performed due to patient" choice in 29 cases (72.5%), for severe pulmonary or cardiovascular disease in disease in 9 patients (22.5) and age over 80 in 2 (5%) patients. A deep TUR-biopsy was performed before and after chemotherapy and an extensive TUR was repeated at the end of radiotherapy. In the first 30 patients chemotherapy consisted of 2-4 cycles of 70 mg/m2 cisplatin on fay 1, and 40 mg/m2 methotrexate on days 8 and 15. In the last 10 patients chemotherapy consisted of 3 cycles of CMV (100 mg/m2 cisplatin on day 2, 30 mg/m2 of vinblastine on days 1 and 8). Total dose of radiotherapy was 60-65 Gy. Recurrent superficial tumors were treated transurethrally. Radical cystectomy, when feasible, was considered for persistent or recurrent invasive disease. RESULTS: after chemotherapy, a clinical objective response was obtained in 27 patients (67.5%), 19 (47.5%) of whom showed a complete response. Thirteen (32.5%) patients showed no response and 5 (12.5%) progressed during chemotherapy. After extensive TUR of any residual mass and radiotherapy, a complete response was achieved in 6 patients who initially showed a partial response and in other 2 patients and stable disease after chemotherapy. Altogether, 27 patients (67.5%) presented had local recurrences, 3 patients underwent cystectomy. Fourteen patients (35%) are alive and 13 NED (65 months mean survival). Five patients died of unrelated disease. Twenty-one patients (52.5%) died of distant metastases (mean survival 28 months). Four patients presented distant metastases after vesical infiltrating recurrence and 4 patients had distant metastases in the absence of loco-regional recurrence. Twenty-two patients (55%) maintained an intact bladder. Patients with complete response to chemotherapy showed a low risk for developing recurrent infiltrating tumors and metastases. CONCLUSIONS: A complete tumor was maintained at 5 years in over 50% of the patients conservatively treated. Bladder salvage is feasible in selected patients.

Adult↗
PubMed1998

[Ultrasonic tissue characterization analysis in type 1 diabetes: a very early index of diabetic cardiomyopathy?].

BACKGROUND: Based on various epidemiological observations, it has been hypothesized that there is a "diabetic cardiomyopathy" strictly related to diabetes per se and probably due to an increase in the collagen content at the myocardial level, to microangiopathy or to complex alteration of myocardial metabolic pattern. Ultrasonic tissue characterization has recently been applied with different methodological approaches in order to identify early structural alterations of the myocardium. METHODS: We used two different methods of myocardial tissue characterization, i.e. integrated backscatter and videodensitometry, to analyze 26 type I diabetics without clinical symptoms, without hypertension or coronary artery disease, which were excluded on the basis of a negative exercise ECG, and in whom conventional echocardiographic parameters were normal. Seventeen healthy age- and sex-matched subjects were evaluated as the control group. RESULTS: Of the common left ventricular functional indexes, only E/A ratio (expression of global diastolic function) was lower in diabetics compared with controls (p < 0.01). The integrated backscatter index (IBI%) at the septum and posterior wall was significantly higher in diabetics as compared to controls, expressing an increased collagen content on a myocardial level. The cyclic variation index (%) of the mean gray level (videodensitometry) was significantly lower in diabetics in comparison with controls, both for the septum (p < 0.0001) and posterior wall (p < 0.002). This probably expresses an altered intrinsic myocardial contractility, due to an increase in myocardial collagen content and/or impairment of micro-circulatory function. CONCLUSION: In agreement with previous studies, we found an altered behavior in myocardial tissue reflectivity in type I diabetics. The real significance of this finding in the "normal" heart is the subject of intense debate. One hypothesis is that these findings could be considered a very early index of a "diabetic cardiomyopathy".

Adult↗
PubMed1997

[Intraoperative tonal-threshold audiometry in the surgery of otosclerosis].

At the end of stapedioplasty, performed under local anesthesia, the surgeon usually tests the hearing function making questions to the patient turning his voice from a soft whisper to a loud tone. At the ENT Department, University of Parma Italy, a more precise method is employed in order to measure the air conduction threshold of the patient at the beginning and at the end of surgery. From April 1996 to October 1996, intraoperative pure-tone audiometry was performed in 36 patients who underwent stapedioplasty. A portable audiometer "Amplaid 161/C Amplifon" was used in the operating room. Air conduction thresholds were measured at 125-8000 Hz. Intraoperative pure-tone audiometry allows an instantaneous and a more accurate evaluation of the surgical functional results.

Adult↗
PubMed1996

Ultrasonic videodensitometric analysis in type 1 diabetic myocardium.

OBJECTIVE: To test the hypothesis that quantitative analysis of two-dimensional echocardiographic gray-level distributions could allow one to detect the early changes in acoustic properties of human diabetes myocardium differentiating it from normal myocardium. METHODS: We evaluated, by two-dimensional echocardiography, 28 asymptomatic type 1 insulin-dependent diabetic patients with normal ventricular function (group A) and 15 age- and sex-matched healthy controls (group B). By selection, all of the diabetics were normotensive and had a negative maximal exercise stress. Echocardiographic images were digitized by using a calibrated digitization system. Quantitative texture analysis was accomplished on data from the septum and posterior wall both at end-diastole and at end-systole. The following parameters were obtained: the mean gray level of the regions of interest, and its absolute SD, skewness, kurtosis, and cyclic variation index. RESULTS: The main result of this study was that the cyclic variation indices of the echo amplitudes of the septum and posterior wall in the diabetic group were significantly lower than those in controls (P < 0.001 and P < 0.002, respectively). Furthermore, the diabetic group had a significantly higher mean gray level of the septum [group A 54.3 +/- 22.5 (mean +/- SD) versus group B 39.7 +/- 9.8, P < 0.03] at end-diastole. The mean gray-level of the posterior wall was similar in the two groups, both at end-diastole and at end-systole. CONCLUSION: Alterations of cyclic echo amplitude (possibly related to collagen deposition) can be detected in asymptomatic diabetic patients with normal resting function. Theoretically, this finding might be considered an early preclinical alteration, potentially related to subsequent development of "diabetic cardiomyopathy'.

Adult↗
PubMed1996

Polynucleotide phosphorylase of Escherichia coli is required for the establishment of bacteriophage P4 immunity.

Bacteriophage P4's superinfection immunity mechanism is unique among those of other known bacteriophages in several respects: (i) the P4 immunity factor is not a protein but a short, stable RNA (CI RNA); (ii) in the prophage the expression of the replication operon is prevented by premature transcription termination rather than by repression of transcription initiation; (iii) transcription termination is controlled via RNA-RNA interactions between the CI RNA and two complementary target sequences on the nascent transcript; and (iv) the CI RNA is produced by processing of the same transcript it controls. It was thought that several host-encoded factors may participate in the molecular events required for P4 immunity expression, i.e., RNA processing, RNA-RNA interactions, and transcription termination. To identify such factors we searched for Escherichia coli mutations that affect P4 lysogenization. One such mutation, bfl-1, severely reduced P4's lysogenization frequency and delayed both the disappearance of the long transcripts that cover the entire replication operon and the appearance of the CI RNA. By physical mapping and genetic analysis we show that bfl-1 is allelic to pnp, which codes for polynucleotide phosphorylase, a 3'-to-5' exonucleolytic enzyme. A previously isolated pnp null mutant (pnp-7) exhibited a phenotype similar to that of bfl-1. These results indicate that the polynucleotide phosphorylase of E. coli is involved with the maturation pathway of bacteriophage P4's RNA immunity factor.

Chromosome Mapping↗
PubMed1996

[Electrocochleography by extra- and transtympanic methods: the results in a group of normal subjects].

Electrocochleography (ECoG) is an electrophysiologic approach to the study of hearing. In ECoG, electrical activity that originates within the cochlea or the auditory nerve is recorded. ECoG represents an evoked or stimulus dependent measure. The electrical potentials which can be analyzed in ECoG are: the cochlear microphonic potential (CM), the summating potential (SP) and the acoustic nerve potential (AP). Two major types of electrocochleography electrodes can be used, transtympanic and extratympanic. Transtympanic ECoG is performed by inserting a long needle electrode, placed through the tympanic membrane onto the promontory. Extratympanic ECoG is recorded by using electrodes placed within the external meatus near the tympanic membrane. At the ENT Department of the University of Parma, ECoG was performed in 10 normal hearing subjects (4 males and 6 females. Their ages ranged from 21 to 29 years (mean 26 years). All subjects underwent ECoG recording simultaneously with extratympanic and transtympanic technique.

Adult↗
PubMed1996

[Brainstem auditory evoked potentials in neonatology: the method and results in a group of normal newborns].

Brainstem evoked responses audiometry was performed on 10 newborn infants. They ranged in postnatal age from 19 hours to 5 days and in estimated gestational age from 39 to 42 weeks. Clicks of 0.1 msec duration were presented at a rate of 11.4 per second. Measurements were made at 50, 80 and 100 dB. Wave V latencies were evaluated at 50, 80 and 100 dB HL in order to measure the auditory threshold. The latency of wave V is the datum of interest. Wave V responses were obtained bilaterally at 50 dB HL. Waves I and III latencies were measured at 100 dB HL.

Acoustic Stimulation↗
PubMed1995

Well-differentiated endocrine tumours of the middle ear and of the hindgut have immunocytochemical and ultrastructural features in common.

The immunocytochemical analysis of two cases of well-differentiated endocrine tumours (carcinoids) of the middle ear revealed predominant cell populations producing pancreatic polypeptide (PP)-related peptides, glucagon-related peptides, and serotonin (the latter only in one case). In consecutive sections PP- and glucagon-related immunoreactivities mainly colocalized in the same tumour cells. Ultrastructurally tumour cells were characterized by medium-sized to large granules of moderate to high density, on which PP and glicentin were localized by the immunogold technique. No amphicrine cells were found. These features are consistent with those of similar tumours in the rectal mucosa that are mainly composed of L cells coexpressing both PP-related and glucagon-related peptides. Additional tumour antigens of hindgut type detected immunohistochemically were prostatic acid phosphatase and CAR-5 mucin. Expression of the CAR-5 antigen was also found in samples of normal middle ear mucosa, in which endocrine cells have not been identified. In case 1 peritumoral mucosal invaginations showed a proliferation of endocrine cells identical immunophenotypically to tumour cells, possibly representing a precursor lesion. It is concluded that well-differentiated endocrine tumours of the middle ear are a distinct pathological entity characterized by multiple hormone production, typically involving three classes of hormones (pancreatic polypeptide-related peptides, glucagon-related peptides, and serotonin) of the hindgut endocrine system.

Adult↗