Fitting the determined impedance in the guinea pig inner ear to Randles circuit using square error minimization in the range of 100 Hz to 50 kHz.

Objective. Several lumped and distributed parameter models of the inner ear have been proposed to improve vestibular implant stimulation. The models should account for all significant physical phenomena that influence the current propagation, such as the electrical double layer (EDL) and medium polarization. The electrical properties of the medium are reflected in the electrical impedance; therefore, the study aimed to measure the impedance in the guinea pig inner ear and construct its equivalent circuit.Approach. The electrical impedance was measured from 100 Hz to 50 kHz between a pair of platinum electrodes immersed in 0.9% NaCl saline solution using sinusoidal voltage signals. The Randles circuit was fitted to the measured impedance in the saline solution in order to estimate the EDL parameters (C,W,andRct) of the electrode interface in saline. Then, the electrical impedance was measured between all combinations of the electrodes located in the semicircular canal ampullae and the vestibular nerve in the guinea pigin vitro. The extended Randles circuit considering the medium polarization (Ri,Re,Cm) together with EDL parameters (C,Rct) obtained from the saline solution was fitted to the measured impedance of the guinea pig inner ear. The Warburg element was assumed negligible and was not considered in the guinea pig model.Main results. For the set-up used, the obtained EDL parameters were:C=27.09*10-8F,Rct=18.75kΩ.The average values of intra-, extracellular resistances, and membrane capacitance wereRi=4.74kΩ,Re=45.05kΩ,Cm=9.69*10-8F,respectively.Significance. The obtained values of the model parameters can serve as a good estimation of the EDL for modelling work. The EDL, together with medium polarization, plays a significant role in the electrical impedance of the guinea pig inner ear, therefore, they should be considered in electrical conductivity models to increase the credibility of the simulations.

Hypoxia modulates the effect of dihydroartemisinin on endothelial cells.

Artemisinin derivatives, the current cornerstone of malaria treatment, possess also anti-angiogenic and anti-tumor activity. Hypoxia plays a crucial role both in severe malaria (as a consequence of the cytoadherence of infected erythrocytes to the microvasculature) and in cancer (due to the restricted blood supply in the growing tumor mass). However, the consequences of hypoxia onto the effects of artemisinins is under-researched. This study aimed at assessing how the inhibition of microvascular endothelial cell (HMEC-1) growth induced by dihydroartemisinin (DHA, an antimalarial drug and the active metabolite of currently in-use artemisinins) is affected by oxygen tension. Low doses of DHA (achieved in the patients' plasma when treating malaria) were more inhibitory in hypoxia, whereas high doses (required for anti-angiogenic or anti-tumor activity) were more effective in normoxia. The peroxide bridge is essential for cellular toxicity (deoxyDHA was inactive). High doses of DHA caused HMEC-1 apoptosis and G2 cell cycle arrest. Effects were mediated by the generation of oxidative stress as demonstrated by DCF-DA fluorescence and membrane lipid peroxidation analysis. Overall, these results suggest that DHA inhibition of endothelial cell growth is related to the level of tissue oxygenation and drug concentration. This should be considered when studying both the effects of artemisinin derivatives as antimalarials and the potential therapeutic applications of these drugs as anti-tumor agents.

Old and new targets for innovative antimalarial compounds: the different strategies of the Italian Malaria Network.

Clinical treatment-failures to affordable drugs encouraged new investigation for discovery and development of new prophylactic and therapeutic interventions against malaria. The Drug Discovery Cluster (DDcl) of the Italian Malaria Network gathers several highly integrated and complementary laboratories from different Italian Institutions to identify, synthesise, screen in vitro and in vivo new antimalarial molecules directed against the intraerythrocytic stage of P. falciparum parasites and/or with transmission blocking activity to select lead compounds for further development. Complementary research activities, both in vitro and in the clinics, aim at investigating the pathogenetic mechanisms of severe malaria anaemia and the different manifestations of the disease in malaria-HIV co-infected patients to identify new therapies and improve survival.

Sex differentiation pattern in the annual fish Austrolebias charrua (Cyprinodontiformes: Rivulidae).

Sex differentiation process, determination of sexual strategy, and gametogenesis of the annual fish Austrolebias charrua are established. Evidence of histological sex differentiation in an antero-posterior gradient was observed in pre-hatching stages. Sexual strategy corresponds to the "differentiated gonochoric" pattern. Histological analyses of adult gonads showed an asynchronous spawning mode for females and continuous spawning for males. Mature oocytes presented fluid yolk. Testis organization corresponded to a restricted spermatogonial model. Herein, we report the ultrastructural organization of the vitelline envelope and the main features of the sperm of A. charrua. Taking together these results also contribute to phylogenetic studies and provide base line data to propose A. charrua as a biomonitor of contamination in a protected area.

Composite lengthened arterial conduits: long-term angiographic results of an uncommon surgical strategy.

BACKGROUND: We sought to evaluate the long-term patency rate of composite lengthened conduits. METHODS AND RESULTS: From December 1991 to April 2000, 43 patients had a composite lengthened arterial conduit. There was a mean of 2.83 +/- 1.23 anastomoses per patient. No 30-day mortality occurred. Five patients died from 3 to 84 months after the operation (mean, 38.6 +/- 34.6 months). After a mean follow-up of 57.0 +/- 32.3 months (range, 3-99 months), all the survivors are asymptomatic. The only cardiac major events recorded were 2 (4.6%) late acute myocardial infarctions in the patients who died. Eight-year survival and event-free survival were both 80.4% +/- 9.1% (range, 3%-93%). In the early period (13.5 +/- 4.8 days) in 26 patients, 26 arterial composite lengthened conduits and 37 distal anastomoses had postoperative angiographic control; all the anastomoses were rates as grade A, according to Fitzgibbon classification. In the late period (29 +/- 30 months) in 23 patients, 23 arterial composite lengthened conduits and 34 distal anastomoses were checked; the patency rate was 22 (95.6%) of 23 for the composite lengthened conduits and 33 (97%) of 34 for the distal anastomoses. CONCLUSIONS: In particular situations, when the length of an arterial conduit is not enough to allow a correct use of the graft, lengthening of an arterial conduit can be a safe and effective technique.

Predicting the biologic behavior of ductal carcinoma in situ: an analysis of molecular markers.

BACKGROUND: Ductal carcinoma in situ (DCIS) of the breast encompasses a heterogeneous group of noninvasive cancers that now represents 19% of new breast cancer cases. Optimal treatment remains controversial. We undertook this study to characterize the relationship between angiogenic markers and the biologic behavior of various DCIS phenotypes. METHODS: We performed histopathologic review and immunohistochemistry for p53, vascular endothelial growth factor (VEGF), and factor VIII-related antigen on 103 specimens of pure DCIS. RESULTS: VEGF expression was seen in 89 tumors (86%) and correlated with microvessel density (MVD). Among VEGF-negative tumors, mean MVD (number of microvessels per square millimeter) was 48 +/- 19, versus 117 +/- 7 for tumors expressing VEGF (P =.001). Strong p53 expression was observed in 28 tumors (27%) and was associated with comedo histology, high tumor grade, necrosis, high MVD, and ipsilateral tumor recurrence (all P < or =.03). Among 8 patients with ipsilateral recurrence, 5 (63%) had tumors with strong p53 expression, whereas only 24% of patients without recurrence had tumors with strong p53 expression (P =.03). Although 7 of 8 patients with ipsilateral recurrence had tumors with VEGF and high MVD, neither parameter achieved statistical significance. CONCLUSIONS: These data suggest that molecular alterations may help predict the biologic aggressiveness of DCIS. Mutant p53 expression predisposes the patient toward ipsilateral recurrence, perhaps by promoting angiogenesis. Further investigation may identify clinically useful markers and novel treatment strategies.

Myocardial revascularization with and without cardiopulmonary bypass in multivessel disease: impact of the strategy on early outcome.

BACKGROUND: The impact of myocardial revascularization without cardiopulmonary bypass (CPB) was evaluated in a series of consecutive patients with multivessel disease. METHODS: From May 21, 1997 to November 30, 2000, 1,843 consecutive patients underwent isolated myocardial revascularization. From this total, 919 patients were done without CPB (group A, 49.9%) and 924 patients were done with CPB (group B, 50.1%). Patients that converted from without CPB to with CPB were included in group A. Thirty-three variables were evaluated with univariate and multivariate analysis to identify the independent variables predictive of higher incidence of early mortality, acute myocardial infarction, cerebrovascular accident, and early major events. RESULTS: Early mortality was 2.2% (group A, 1.4%; group B, 3.0%; p = 0.016), acute myocardial infarction incidence was 1.8% (group A, 1.1%; group B, 2.6%; p = 0.027), cerebrovascular accident incidence was 0.9% (group A, 0.8%; group B, 1.0%; p = not significant), and early major events incidence was 6.7% (group A, 5.3%; group B, 8.2%; p < 0.001). Stepwise logistic regression analysis showed that CPB was an independent risk factor for higher mortality (odds ratio, 2.2; p = 0.0217), higher incidence of acute myocardial infarction (odds ratio, 2.5; p = 0.0185), and higher incidence of early major events (odds ratio, 1.8, p = 0.0034). CONCLUSIONS: When CPB was not used, patients experienced lower early mortality and incidences of acute myocardial infarction were less complicated, both at univariate analysis and stepwise logistic regression analysis.

Mitral valve procedure in dilated cardiomyopathy: repair or replacement?

BACKGROUND: Mitral valve (MV) procedure for dilated cardiomyopathy is becoming popular. We analyzed the indications to MV repair or replacement according to our 10-year experience. METHODS: From January 1990 to May 2000, 49 patients with dilated cardiomyopathy (12 idiopathic and 37 ischemic) underwent MV operation, 29 repair and 20 replacement. Preoperative evaluation included measurement of MV coaptation depth (CD) as a mirror of the abnormalities of MV apparatus leading to functional mitral regurgitation. RESULTS: Thirty-day mortality was 4.2% (2 patients). One-, 3-, 5-, and 10-year actuarial survival was, respectively, 90%, 87%, 78%, and 73%. The possibility of survival with at least one New York Heart Association functional class improvement was 88%, 76%, 71%, and 65%. Return of functional mitral regurgitation after MV repair was nearly inevitable; however, using a scale from 0 to 4, mean postoperative functional mitral regurgitation was 1.2+/-0.8 when preoperative MVCD was 10 mm or less and 2.5+/-0.7 when preoperative MVCD was 11 mm or higher (p < 0.05). Globally, functional results were not influenced by the strategy of treatment (MV repair or replacement). CONCLUSIONS: Mitral valve operation can give satisfying survival and good palliation of dilated cardiomyopathy. The MVCD can be helpful in the choice of the surgical strategy on the MV.

Early clinical experience with a new sutureless anastomotic device for proximal anastomosis of the saphenous vein to the aorta.

BACKGROUND: Avoiding aortic side clamping is useful to avoid local particulate embolization. A device that allows a saphenous vein graft to be anastomosed to the aorta without aortic manipulation is clinically evaluated. METHODS AND RESULTS: From July 1999 to March 2000, 17 patients who underwent myocardial revascularization had an aorta-saphenous vein graft anastomosis performed by means of an aortic anastomotic device. Eight were operated on with cardiopulmonary bypass and 9 without. The proximal anastomoses created by the aortic anastomotic device were performed before the institution of cardiopulmonary bypass or before the related distal anastomosis was performed. In 11 patients transcranial Doppler ultrasound was used. In 1 (6%) patient the saphenous vein graft was not deployed, and in 2 (12%) a single suture was added for minor bleeding. None of the 11 patients evaluated with transcranial Doppler ultrasound had evidence of particulate embolization during the procedure. No patient died or was reoperated on for bleeding. Six (35%) patients had a postoperative angiogram 48 +/- 26 days after the operation that showed widely patent proximal anastomoses. CONCLUSIONS: Use of an aortic anastomotic device allows a sutureless anastomosis to be created between the aorta and saphenous vein graft. The device could be used in totally endoscopic myocardial revascularization. A second-generation device is ready to solve the problems encountered and to increase the ease in handling the device.

[Anesthetics management in patients with epidermolysis bullosa]. / Condotta anestesiologica in un paziente affetto da epidermolisi bollosa.

The anesthetic management used in a 4-yr-old boy with dystrophic epidermolysis bullosa (DEB) submitted to long-lasting urological surgery is reported. Medical treatment of cutaneous bullae in various stages of healing was undertaken preoperatively. Other preoperative therapies were performed to treat sepsis and to improve poor nutritional state. Different measures were used during monitoring and inhalation induction and maintenance of anesthesia in order to prevent frictional trauma to the skin and oropharyngeal mucosa, leading to blistering. Anesthesia and surgery proceeded uneventfully, while surgical complications and sepsis occurred postoperatively. However the patient was discharged from intensive care unit to surgical ward on 35 postoperative days without evidence of oropharyngeal bullae and with a good improvement of his cutaneous condition. The conclusions are drawn that, even if the patient with DEB represents a challenge to the anesthesiologist, a long-lasting surgical intervention can be performed successfully. The main aspect in the anesthetic management of these patients is the detailed knowledge of all problems that anesthesiologist must face and solve to preserve skin and mucosa integrity, avoiding the risk of severe complications.

[Anesthesiologic management of susceptible children at risk for malignant hyperthermia]. / Condotta anestesiologica in soggetti pediatrici a rischio di ipertermia maligna.

In order to prevent malignant hyperthermia (MH) in children, the authors are currently using a perioperative anaesthetic protocol. In vitro contracture tests with halothane and caffein are performed in selected patients: those with previous signs suggestive of MH, but not severe enough for a definite diagnosis; those with susceptibility to MH in their relatives; those affected by myopathies or other disorders very frequently associated with MH. Even though CK should be considered an unreliable predictor of MH susceptibility, trigger agents are avoided in children with high and constant CK levels. However, prophylactic dantrolene is never employed. In this way, over the last decade no episodes of classic malignant hyperthermia in a large number of children submitted to anaesthesia (more than 50,000) have been observed.

[Combined craniofacial surgery in malignant tumors of the ethmoid]. / Il trattamento chirurgico combinato cranio-facciale nei tumori maligni dell'etmoide.

The Authors discuss the importance of surgical treatment in ethmoid cancer basing their discussion upon observation of three cases involving the anterior skull base which followed an overview of the epidemiology, histology and evaluation of this kind of pathology. After reviewing Literature they stress the validity of anterior craniofacial resection which allows a wide exposure of the complex anatomic structures at the base of the skull and a monoblock resection of malignant tumors as well as a satisfactory reconstruction of the resulting defect at the skull base. Furthermore, they emphasize the still existing differences among many Authors as far as surgical technique is concerned and the extreme variability of the survival rate. The Authors conclude that in order to make a comparison between the results of different Authors, data concerning the site of origin, the extension and the histology of the tumors and the length of the follow-up should be more homogeneous.

Changes in human parotid salivary protein and sialic acid levels during pregnancy.

Saliva was collected with a Carlson-Crittenden device, under citric acid stimulation, in 107 pregnant women, 9 puerperal and 7 non-pregnant controls. No significant changes were found in salivary flow rate, pH and amylase levels. The total protein levels were decreased during pregnancy and the puerperium. The sialic acid levels decreased gradually but markedly during pregnancy, returning to normal levels in the puerperium. These changes in parotid saliva may be related to the hormonal changes of pregnancy.

Internalization and degradation of human alpha-A interferon bound to bovine MDBK cells: regulation of the decay and resynthesis of receptors.

The binding of 125I-labeled human interferon alpha-A (HuIFN-alpha A) to receptors of bovine MDBK cells was investigated. About 4-fold more 125I-interferon was bound at 37 degrees C than at 0 degrees C. To establish whether the cell-bound IFN was internalized, the cells were treated with diluted acetic acid, a procedure known to remove polypeptides bound to the cell surface. About 80% of the IFN bound at 0 degrees C was dissociated from the cells by this treatment, whereas only 45% of that bound after a 2 h incubation at 37 degrees C was dissociated. Release of cell-bound 125I-interferon by cells washed and incubated in fresh medium was next examined at the two temperatures. At 0 degrees C, up to 50% of cell-bound IFN was released into the medium over a 2 h period, whereas at 37 degrees C the cell-bound radioactivity was slowly released over several hours as acid-soluble degradation products. Interferon was therefore internalized and degraded by MDBK cells incubated at 37 degrees C, but not by cells incubated at 0 degrees C. The increased binding at 37 degrees C could possibly be explained by the internalization of IFN/receptor complexes and by the recycling of the receptors to the cell surface. This recycling was limited, however, since incubation of MDBK cells with unlabeled IFN led to a rapid decrease or down regulation of available receptors. Recovery of binding activity was prevented by the addition of inhibitors of protein and RNA synthesis, suggesting that de novo synthesis of receptors was required. The half-life of the IFN receptor in the presence of cycloheximide was about 3 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of interferon with cellular receptors. Internalization and degradation of cell-bound interferon.

Human interferon alpha A, produced in Escherichia coli by recombinant DNA technology, was labeled with 125I to study its binding to receptors on human lymphoblastoid Daudi cells. This binding showed a marked temperature dependency, with maximum binding obtained at 30-37 degrees C. About 60% of the cell-bound radioactivity was released upon subsequent addition of unlabeled interferon, indicating that only part of the cell-bound interferon could be displaced by competitor. Moreover, about 30-50% of cell-bound interferon was not released by treating the cells with 0.2 N acetic acid, a procedure which removes polypeptide hormones on the cell surface, indicating that part of the interferon bound at 37 degrees C was internalized. This interferon was slowly degraded to acid-soluble products, which were released into the culture medium. Treatment of DAudi cells with the lysosomotropic amines chloroquine and methylamine inhibited the degradation of interferon. Methylamine, however, also inhibited the internalization of interferon. Daudi cells treated with interferon in the presence of chloroquine showed an increase in the interferon-induced enzyme 2',5'-oligo(A) polymerase comparable to that of cells treated with interferon alone. This enzyme increased to a similar extent in cells treated with interferon and cytochalasin, a drug which inhibited internalization of interferon by 50%. These results suggest that degradation and possibly internalization of interferon are not required for at least some of its biological activities.

Analogs of (2'-5')oligo(A). Endonuclease activation and inhibition of protein synthesis in intact cells.

Synthetic analogs of (2'-5')oligo(A) were assayed for endonuclease activation in cell extracts and for inhibition of protein synthesis in intact cells. The analogs are triadenylates: (i) methylated in the terminal 3'-OH; (ii) methylated at all three 3'-OH groups; (iii) with different numbers of phosphate groups at the 5' terminus or with a methylene group between the beta- and gamma-phosphate. Only 5'-phosphorylated monomethylated analogs activate an endonuclease in cell extracts and are powerful inhibitors of protein synthesis in intact cells. The analogs with only one 5'-terminal phosphate may require addition of another phosphate for activity since the kinase inhibitor 2-aminopurine prevents endonuclease activation by this compound but not by the di- and triphosphate-terminated triadenylates. These results suggest that two terminal phosphates and one or two free 3'-OH are required for endonuclease activation and inhibition of protein synthesis. The monomethylated analogs are more active than (2'-5')pppA3 because of their resistance to degradation by cellular enzymes. Accordingly, the monomethylated analogs cause a prolonged inhibition of protein synthesis in human fibroblasts treated with nanomolar concentrations of these compounds.

Immunoglobulins in periodontal tissues. II. Concentrations of immunoglobulins in granulation tissue from pockets of periodontosis and periodontitis patients.

In recent years evidence in the literature has indicated that the immune response may play an important role in the initiation and progression of the periodontal diseases. A study was initiated to determine the IgA, IgG, and IgM concentrations in the granulation tissue removed from deep infrabony pockets of patients with periodontosis and advanced periodontitis. Comparison of mean immunoglobulin levels between the periodontosis and periodontitis groups revealed a statistically significant increase (P less than 0.05) for IgG in the granulation tissue from the periodontosis group. The possible implications of these findings are discussed.

Immunoglobulins in periodontal tissues. III. Concentrations of immunoglobulins in dilantin-induced and idiopathic gingival hyperplastic tissues.

Immunoglobulin levels in both Dilantin-induced and idiopathic hyperplastic gingiva were determined and compared with the concentrations in normal gingival tissue. A statistically significant increase in IgG was found in Dilantin hyperplastic tissue, but no significant difference could be shown for idiopathic gingival hyperplasia. IgA levels did not differ significantly in the three types of tissue assayed. IgM was detected in 90% of the Dilantin hyperplastic gingival specimens assayed (mean GI = 1.2) and in 75% of the idiopathic hyperplastic tissue (mean GI = 0.7). This incidence of IgM detection was higher than that reported for normal and inflamed gingiva from periodontitis patients. The significance of these findings and possible correlation with the degree of tissue inflammation are discussed.