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Biomedical subjects

A Mazzoni

Publications and source records attributed to A Mazzoni.

At least 19 recordsLinked to original sources
PubMed2006

Electric-current-assisted application of self-etch adhesives to dentin.

The use of electric current during the application of etch-and-rinse adhesive systems has been recently claimed to increase bonding of etch-and-rinse adhesives by enhancing substrate impregnation. The null hypothesis tested in this study was that electrically assisted application has no effect on bond strength of self-etching bonding systems. Three self-etch adhesives (Protect-Bond, Xeno III, and Prompt L-Pop) were applied with the aid of an electric signal-generating device (ElectroBond) and tested vs. controls prepared with the same disposable sponges but without electric current. Specimens bonded under the influence of electric current exhibited increased microtensile bond strength compared with the controls (p<0.05). High-resolution SEM analysis showed that bonding under the influence of electricity reduced interfacial nanoleakage. It is speculated that resin infiltration may be improved by the attraction of polar monomers by an electric current or by modification of the dentin surface charges, resulting in better water substitution or evaporation.

Ammonia↗
PubMed2004

Plasma exchange for polyradiculoneuropathy following kidney transplantation: a case report.

We describe a case of polyradiculoneuropathy (PRN) following living donor kidney transplantation, without clinical evidence of preexisting infection. In this study plasma exchange treatment resulted 6 days later in improvement in extremity weakness and paresthesias in the upper and lower extremities. Total neurological recovery was obtained 3 months after the onset of symptoms.

Humans↗
PubMed2004

The use of extracorporeal photopheresis for allograft rejection in liver transplant recipients.

BACKGROUND: Originally introduced for cutaneous T-cell lymphomas and autoimmune diseases, extracorporeal photopheresis (ECP) has been proven effective to reverse allograft rejection. The aim of the present work was to show the results of a single-center experience with ECP for the treatment of biopsy-proven rejection in selected liver transplant (LT) recipients. PATIENTS AND METHODS: A retrospective review of five LT patients (M:F=4:1; median age 51 years) undergoing ECP for biopsy-proven allograft rejection between January 1996 and December 2003. In this period 476 LT were performed on 441 patients. RESULTS: The indications for LT were three cases of HCV-related cirrhosis, complicated by hepatocellular carcinoma in two; one HBV-HDV-alcoholic cirrhosis; and one fulminant HBV hepatitis. All patients received calcineurin-inhibitor (CNI)-based immunosuppression with induction using anti-IL2R monoclonal antibodies. Indications for ECP were: ductopenic rejection in one patient with HCV recurrence; steroid-resistant acute rejection in two; acute rejection in a major ABO-mismatched liver graft; and one acute rejection in a patient with a proven allergy to steroids. The median interval from LT to inception of ECP was 43 days. The median number of ECP sessions per patient was 20. During the course of ECP, two patients tested positive for CMV antigenemia, associated in one case with bacterial pneumonia. All patients tolerated ECP and there were no procedure-related complications. At a median follow-up of 7.9 months after start of ECP, neither rejection relapses nor HCV/HBV recurrences have been observed. Three patients are off ECP with complete reversal and low-dose immunosuppression. Two patients are still receiving ECP with full-dose immunosuppression: one has achieved normal liver function but ECP is indicated due to a major ABO-incompatible liver graft, while the other patient's liver functions have not yet returned to baseline values.

Adult↗
PubMed2004

Comparative evaluation of Sensititre YeastOne vs. the NCCLS M27A protocol and E-test for antifungal susceptibility testing of yeasts.

A recently developed microdilution method (Sensititre) YeastOne) may represent a valid alternative to the National Committee for Clinical Laboratory Standards (NCCLS) method for routine testing. The Medical Mycology Committee of the Associazione Microbiologi Clinici Italiani (AMCLI) decided to evaluate its reproducibility and reliability compared with the NCCLS M27A protocol and the E-test. Nineteen strains each of Candida albicans and Ca. parapsilosis, isolated from systemic infections, were tested against amphotericin B, flucytosine, ketoconazole, itraconazole, and fluconazole. All the participating laboratories tested the YeastOne panels, while the E-test and the NCCLS method were performed by two laboratories each. Interlaboratory reproducibility showed a good correlation (from 95% for amphotericin B to 92.5% for flucytosine). The agreement between NCCLS and YeastOne ranged from 95 (ketoconazole and itraconazole) to 100% (amphotericin B and flucytosine), whereas the agreement between E-test and YeastOne ranged from 72.5 (fluconazole) to 100% (amphotericin B and flucytosine). The Sensititre YeastOne panels appear to be an excellent alternative to both the E-test and the NCCLS protocol for antifungal susceptibility testing.

Amphotericin B↗
PubMed2003

Combined twice-daily plasma exchange and continuous veno-venous hemodiafiltration for bridging severe acute liver failure.

Aiming to remove the toxins produced during the course of severe hepatic failure, we combined hemodiafiltration and plasma exchange (patient plasma replaced by fresh frozen plasma in a twice-daily regimen) for treatment of five patients: two affected by primary nonfunction of a liver graft and three by fulminant hepatic failure. The simultaneous use of the two extracorporeal techniques allowed a rapid reduction in the administration of vasoactive drugs and a rapid, significant decrease in the indices of liver necrosis. Native liver functional recovery occurred in one case, and the wait for a second graft was made possible in the other four. Although it has been reported that the detoxifying efficacy of plasma exchange is optimal when the replaced volume of plasma is high, such a technique requires both long treatment times and high blood flows in the extracorporeal circuit, making it often hemodynamically intolerable. Our approach leads to replacement of smaller volumes, allowing lower blood flows that are better tolerated despite the often unstable hemodynamics of these patients. Liver transplantation and retransplantation remains the definite therapy for severe liver failure or primary nonfunction. However, the organ waiting time is unpredictable and often does not coincide with the patients' clinical needs. Thus alternative strategies must be developed until a suitable donor is found or there is spontaneous recovery. From this point of view, in our albeit limited experience, twice-daily plasma exchange combined with hemodiafiltration has proved to be an effective therapeutic approach.

Acute Disease↗
PubMed2001

Secreted MD-2 is a large polymeric protein that efficiently confers lipopolysaccharide sensitivity to Toll-like receptor 4.

Toll-like receptor 4 (TLR4), the principal signaling receptor for lipopolysaccharide (LPS) in mammals, requires the binding of MD-2 to its extracellular domain for maximal responsiveness. MD-2 contains a leader sequence but lacks a transmembrane domain, and we asked whether it is secreted into the medium as an active protein. As a source of secreted MD-2 (sMD-2), we used culture supernatants from cells stably transduced with epitope-tagged human MD-2. We show that sMD-2 exists as a heterogeneous collection of large disulfide-linked oligomers formed from stable dimeric subunits and that concentrations of sMD-2 as low as 50 pM enhance the responsiveness of TLR4 reporter cells to LPS. An MD-2-like activity is also released by monocyte-derived dendritic cells from normal donors. When coexpressed, TLR4 indiscriminately associates in the endoplasmic reticulum/cis Golgi with different-sized oligomers of MD-2, and excess MD-2 is secreted into the medium. We conclude that normal and transfected cells secrete a soluble form of MD-2 that binds with high affinity to TLR4 and that could play a role in regulating responses to LPS and other pathogen-derived substances in vivo.

Antigens, Surface↗
PubMed2001

Regulation of Toll-like receptors in human monocytes and dendritic cells.

A number of pathogens induce immature dendritic cells (iDC) to migrate to lymphoid organs where, as mature DC (mDC), they serve as efficient APC. We hypothesized that pathogen recognition by iDC is mediated by Toll-like receptors (TLRs), and asked which TLRs are expressed during the progression of monocytes to mDC. We first measured mRNA levels for TLRs 1-5 and MD2 (a protein required for TLR4 function) by Northern analysis. For most TLRs, message expression decreased severalfold as monocytes differentiated into iDC, but opposing this trend, TLR3 and MD2 showed marked increases during iDC formation. When iDC were induced to mature with LPS or TNF-alpha, expression of most TLRs transiently increased and then nearly disappeared. Stimulation of iDC, but not mDC, with LPS resulted in the activation of IL-1 receptor-associated kinase, an early component in the TLR signaling pathway, strongly suggesting that LPS signals through a TLR. Surface expression of TLRs 1 and 4, as measured by mAb binding, was very low, corresponding to a few thousand molecules per cell in monocytes, and a few hundred or less in iDC. We conclude that TLRs are expressed in iDC and are involved in responses to at least one pathogen-derived substance, LPS. If TLR4 is solely responsible for LPS signaling in humans, as it is in mice, then its extremely low surface expression implies that it is a very efficient signal transducer in iDC.

Antigens, Surface↗
PubMed2001

Histoplasma capsulatum var. capsulatum occurring in an HIV-positive Ghanaian immigrant to Italy. Identification of H. capsulatum DNA by PCR from paraffin sample.

Histoplasmosis, which is highly endemic in the United States, is rare in Europe, usually imported but sometimes autochthonous. In Africa, histoplasmosis capsulati coexists with "African histoplasmosis", a characteristic skin infection caused by H. capsulatum var. duboisii. Histoplamosis due to H. capsulatum is one of the 12 secondary infections listed in the surveillance definitions of AIDS. We report the case of a 36-year-old black man with acquired immunodeficiency syndrome (AIDS) who was living in Italy but originally came from Ghana. Histoplasmosis was disseminated with fever and cutaneous manifestations. The diagnosis was demonstrated morphologically based on the presence of yeast, observed by light microscopy, in skin lesions and by identification of H. capsulatum var. capsulatum DNA by nested PCR from a paraffin sample. No clinical reports of histoplamosis capsulati in Ghana have been published until now. The present case stresses the role of immigration of subjects from outside Europe who have been infected in their native country.

AIDS-Related Opportunistic Infections↗
PubMed2001

Histamine regulates cytokine production in maturing dendritic cells, resulting in altered T cell polarization.

Atopic diseases such as allergy and asthma are characterized by increases in Th2 cells and serum IgE antibodies. The binding of allergens to IgE on mast cells triggers the release of several mediators, of which histamine is the most prevalent. Here we show that histamine, together with a maturation signal, acts directly upon immature dendritic cells (iDCs), profoundly altering their T cell polarizing capacity. We demonstrate that iDCs express two active histamine receptors, H1 and H2. Histamine did not significantly affect the LPS-driven maturation of iDCs with regard to phenotypic changes or capacity to prime naive T cells, but it dramatically altered the repertoire of cytokines and chemokines secreted by mature DCs. In particular, histamine, acting upon the H2 receptor for a short period of time, increased IL-10 production and reduced IL-12 secretion. As a result, histamine-matured DCs polarized naive CD4(+) T cells toward a Th2 phenotype, as compared with DCs that had matured in the absence of histamine. We propose that the Th2 cells favor IgE production, leading to increased histamine secretion by mast cells, thus creating a positive feedback loop that could contribute to the severity of atopic diseases.

Cell Polarity↗
PubMed2000

Immortalized myeloid suppressor cells trigger apoptosis in antigen-activated T lymphocytes.

We described a generalized suppression of CTL anamnestic responses that occurred in mice bearing large tumor nodules or immunized with powerful recombinant viral immunogens. Immune suppression entirely depended on GM-CSF-driven accumulation of CD11b(+)/Gr-1(+) myeloid suppressor cells (MSC) in secondary lymphoid organs. To further investigate the nature and properties of MSC, we immortalized CD11b(+)/Gr-1(+) cells isolated from the spleens of immunosuppressed mice, using a retrovirus encoding the v-myc and v-raf oncogenes. Immortalized cells expressed monocyte/macrophage markers (CD11b, F4/80, CD86, CD11c), but they differed from previously characterized macrophage lines in their capacities to inhibit T lymphocyte activation. Two MSC lines, MSC-1 and MSC-2, were selected based upon their abilities to inhibit Ag-specific proliferative and functional CTL responses. MSC-1 line was constitutively inhibitory, while suppressive functions of MSC-2 line were stimulated by exposure to the cytokine IL-4. Both MSC lines triggered the apoptotic cascade in Ag-activated T lymphocytes by a mechanism requiring cell-cell contact. Some well-known membrane molecules involved in the activation of apoptotic pathways (e.g., TNF-related apoptosis-inducing ligand, Fas ligand, TNF-alpha) were ruled out as candidate effectors for the suppression mechanism. The immortalized myeloid lines represent a novel, useful tool to shed light on the molecules involved in the differentiation of myeloid-related suppressors as well as in the inhibitory pathway they use to control T lymphocyte activation.

3T3 Cells↗
PubMed2000

Anterior approaches in juvenile nasopharyngeal angiofibromas with intracranial extension.

Although surgery is regarded as the mainstay of treatment for juvenile nasopharyngeal angiofibromas (JNAs), ancillary treatment modalities such as radiotherapy and on rare occasions chemotherapy are still recommended by many for intracranial extension with apparent radiologic involvement of the cavernous sinus and internal carotid artery. Further, most authors undertaking surgical excision of this subgroup of patients would recommend a lateral or combined frontal and lateral approach for its removal. In a series of 49 cases of JNA, 14 were found during surgery to have intracranial extradural extension; the anterior approach was used for their removal. Although in these cases, on radiography the cavernous sinus often looked to be invaded and the internal carotid artery was displaced superolaterally, there was no difficulty in establishing a plane of dissection. Total removal was achieved in 11 of the 14 cases with a single-stage procedure. Of the 3 cases with residual tumor, only 1 occurred intracranially. Removal was achieved by a subtemporal approach in this case. For the extracranial residual tumors 1 required a midface degloving and the other, with a 1-cm residual tumor in the nasopharynx, has been treated conservatively for 6 years with no evidence of growth. No deaths or significant complications have occurred, and radiotherapy has not been required. We conclude that JNAs are tumors with a predilection for spread but that rarely invade dura, acting instead to displace it. We believe that surgery is the method of choice for treating these lesions and that an anterior surgical approach with microsurgical techniques should be used in the first instance. In the last 2 cases we preferred a midface degloving technique to avoid facial scarring and because this approach allows a widening of the surgical field if needed by the performance of bilateral maxillary free bone flaps. On the rare occasion that a lateral approach, with its attendant permanent conductive hearing loss, is found to be necessary for total tumor removal, this can be done as a staged procedure. This may be necessary when the tumor has spread lateral to the horizontal internal carotid artery.

Adolescent↗
PubMed2000

A modified retrosigmoid approach for direct exposure of the fundus of the internal auditory canal for hearing preservation in acoustic neuroma surgery.

OBJECTIVE: This is a clinical report on a modified retrosigmoid approach with direct exposure of the fundus of the internal auditory canal for hearing preservation in acoustic neuroma surgery. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center of an ear, nose, and throat department in a public hospital. PATIENTS: One hundred fifty consecutive procedures were reviewed, including 61 males and 89 females with an age range of 13 to 69 years and a mean age of 47 years. There were 15 patients with tumor occupying solely the internal auditory canal and 135 patients with extension into the cerebellopontine angle with an extrameatal diameter of up to 52 mm and a mean of 11.5 mm. INTERVENTION: The retrosigmoid approach included a wide craniotomy, a perimeatal petrous bone removal up to the blue line of the labyrinth, and a direct exposure of the fundus at the orifices of the facial and cochlear nerves. The quadrant of the superior vestibular nerve remained unexposed. MAIN OUTCOME MEASURES: Hearing was measured according to the American Academy of Otolaryngology-Head and Neck Surgery criteria for reporting results of hearing preservation and by comparison with the preoperative level. Facial nerve function was measured using the House-Brackmann grading. The radicality of tumor removal was investigated with mid- to long-term magnetic resonance imaging (MRI). RESULTS: Measurable hearing was preserved in 45.3%, and in 32.4% of these cases, it was within 15 dB/15% discrimination. Grade 1 or 2 facial function was preserved in 85.3%. MRI follow-up revealed a 3.3% tumor residual or regrowth in the complete series. No residual tumor was found at the 3-year MRI in the last series of patients operated on with direct control of the fundus. CONCLUSIONS: This modified retrosigmoid approach permits the direct exposure of the facial and cochlear quadrants of the fundus. This allows tumor dissection under direct visual control. Removing the tumor from the vestibular quadrant of the fundus is done blindly in a minority of cases and carries a minimal risk of residual tumor. This technique requires only conventional equipment and skills of neurotology.

Adolescent↗
PubMed2000

Histopathological evidence of North American blastomycosis in Italy: report of two cases.

No clinical reports of blastomycosis in Italy have been published until now. We here report two cases of histologically diagnosed, unexpected cutaneous involvement in patients, aged 78 and 52 years, living in North Italy and never having been abroad. The histological differential diagnosis between blastomycosis and other fungal pathogens is discussed. Even in the absence of culture the present cases can confidently be considered as genuine examples of Blastomyces dermatitidis infection in Italy.

Adult↗
PubMed2000

Short-term antibiotic prophylaxis for the prevention of wound infection and secondary meningitis in acoustic neuroma surgery: a ten-year experience in a regional hospital.

Wound infection and secondary meningitis are important complications for patients undergoing acoustic neuroma surgery. The Authors retrospectively evaluated the efficacy of a short-term protocol utilizing vancomycin and netilmicin. 434 patients underwent acoustic neuroma surgery in the Otorhinolaryngology Division, A.O. Ospedali Riuniti di Bergamo, from February 1987 to February 1997. Perioperative short-term prophylaxis was administered with vancomycin plus netilmicin. The utility of the prophylaxis schedule was evaluated on the basis of the occurrence of infectious episodes during the first 10-day follow-up. Only 2 episodes (0.5%) of bacterial meningitis were observed.

Anti-Bacterial Agents↗
PubMed1999

CD38 triggers cytotoxic responses in activated human natural killer cells.

Receptors used by natural killer (NK) cells to mediate natural cytotoxicity are poorly defined, although it is now clear that a number of adhesion molecules can serve this function. CD38 transduces signals on T- and B-cell lines, and we asked whether it could trigger lytic and secretory responses in human NK cells. By using an anti-CD38 monoclonal antibody in reverse antibody-dependent cellular cytotoxicity experiments, it is shown that CD38 engagement triggers cytotoxic responses by activated NK cells, but not by cytotoxic T lymphocytes or fresh NK cells. Cross-linking with anti-CD38 F(ab')(2) caused activated NK cells to release granzymes and cytokines, but did not trigger an increase in intracellular Ca(2+). Fresh NK cells acquired CD38-dependent lytic function during activation with interleukin-2 (IL-2), and inhibitor studies suggested that IL-2 stimulated the de novo expression of proteins that act between CD38 and the lytic machinery in NK cells. The induction of proteins that link commonly expressed adhesion molecules to effector mechanisms could provide a paradigm for pathogen recognition by the innate immune system.

ADP-ribosyl Cyclase↗