[Handling of material, including paraffin-embedded specimens, for diagnosis by electron microscopy].
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Breast Neoplasms↗
Biomedical subjects
V Torre
Publications and source records attributed to V Torre.
[Polymorphism of poorly differentiated rhinopharyngeal carcinoma: description of 3 cases].
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Adult↗
[Diagnostic considerations in a case of poorly differentiated carcinoma of the mediastinum].
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Biomarkers, Tumor↗
[Morphological study of the palatine tonsils: clinical and histopathological considerations].
This study examined 71 pediatric tonsillectomy patients through accurate case history and clinical examination, placing particular emphasis on pathologies concomitant to tonsillopathy. In an attempt to find anatomo-clinical correlations, these data were processed together with the results of a histomorphological study of thetonsil epithelium, performed on all tonsillectomy samples. The majority of these patients were females and none more than 13 years of age. Numerous pathologies were found associated with the tonsillopathy and in varying combinations, first and foremost of which was adenoid hypertrophy. Only approximately one fifth of the patients did not show any concomitant pathology of note. All patients presented a history of recurrent pharyngotonsillitis (at least 4 episodes a year) with symptoms arising from 1 to 10 years prior to surgery. The concomitant pathologies included: respiratory, cutaneous and food allergies, asthma, obstructive sleep apnea, rheumatic diseases, etc. From the histomorphological point of view, particular modifications were found in the follicle epithelium and interstitial cells of the palatine tonsil. An exasperated fibrotic interstitial reaction and chronic duration of the disease appeared to prevent tonsil filter function, facilitating chronicization of the tonsillopathy or onset of recurrent infections and concomitant allergies. In the allergic patients the tonsil epithelium was thickened and compact and showed various degrees of chorion edema, in agreement with what is found in the literature. On the contrary, few morphostructural palatine tonsil mutations were found in those subjects which did not present any concomitant pathology or were affected by tonsillopathy of brief duration. All the histomorphological modifications encountered appear related to the individual patient history, confirming the hypothesis that tonsil epithelium can not only condition the evolution of tonsillopathy--reflecting the effect of various factors--but, above all, it directs the immune response, thus playing a role in the development of various concomitant pathologies.
Adolescent↗
[Laryngeal tuberculosis: considerations on the most recent clinical and epidemiological data and presentation of a case report].
According to the "Global Tuberculosis Control" performed in 1999--the third complete, international, global report on tuberculosis infection--173 countries reported their infection data to the WHO; of these countries 102 met the criteria for "DOTS programs" at the end of 1997. The DOTS programs are the only control strategy able to produce a cure rate of 85%. Both at the national and international (Centers of Disease Control) levels, guidelines have been drawn up to improve and coordinate the fight against tuberculosis. New indicators and methods of analysis should be developed to quantify the full impact on the control of infection transmission, incidence, prevalence, mortality and prevention of drug resistance. In addition, two significant world-wide events have affected the increase morbidity rate seen in the last decade in the more highly industrial countries: immigration from countries outside the European Community and HIV infection. The tuberculosis infection worsens the evolution of HIV, facilitating viral replication. In the present work the authors discuss the most recent epidemiological data regarding tuberculosis infection and review the Literature on the primary laryngeal location of the disease. Then they present a clinical case which recently came under observation. This case is a typical example of the clinical picture of the laryngeal tuberculosis seen today. It must not be forgotten that in recent years there has been an increase in morbidity in Italy, in both the pulmonary and extrapulmonary forms of the disease, although in our country the problem of delayed or incomplete reporting is quite widespread. The data show that the age ranges with the highest incidence of both pulmonary and extrapulmonary forms are the 25-35 and 60-70 year groups. Distribution by sex, on the hand, shows that the pulmonary forms are most often seen in males while the extrapulmonary forms have practical the same frequency in both sexes. In recent years the clinical and morphological aspects of tubercular laryngitis have changed significantly from what they were before chemotherapy and the most common clinical form is pseudotumoral tuberculosis. This form requires a differential diagnosis to distinguish it from neoplasms because they present a similar objective picture and have no signs of simultaneous or previous pulmonary involvement.
Diagnosis, Differential↗
[Biphasic hypopharyngeal synovial sarcoma: ultrastructural, cytofluorometric and immunohistochemical study and brief review of the literature].
Synovial sarcomas account for 7-10% of all soft tissue malignancies and the rare head and neck region location accounts for an average 5% of them. A brief review of the data in the Literature has shown that not more than one hundred cases of cervical-facial synovial sarcoma have been reported. In the head and neck locations this form of tumor is significantly less aggressive, with a higher survival rate and a recurrence rate much lower than the 60-70% shown for other locations in the limbs. After a brief review of the Literature, Authors present a rare clinical case of hypopharyngeal synovial sarcoma which recently came under observation. Despite the accurate diagnostic procedure, after surgical removal of the tumor by CO2 laser microlaryngoscopy, diagnosis required the use of histological and ultrastructural techniques. CT and NMR of the neck using contrast medium showed that the structure of the neoformation was similar to that of the soft tissues, it was 3-4 cm in diameter, located in the hypopharynx and had an extensive surface in contact with the left glossoepiglottic groove. The lesion appeared to involve the free edge of the aryepiglottic fold, coming into contact with the free edge of the epiglottis; it could not be dissociated form the epiglottis and obliterated both the homolateral glossoepiglottic vallecula and the pyriform sinus. Structural analysis after radiography with a contrast medium showed a marked impregnation of the lesion, indicative of high degree of vascolarization. Ultrastructural, cytofluormetric and immunohistochemical analyses were performed on the neoplasm in order to process all these data together with the clinical parameters; in other words a multi-parameter evaluation was performed, as suggested by other Authors, to determine the therapy and arrange more accurate monitoring of this patient, victim of a neoplasm with a high potential for metastases.
Adolescent↗
[Description of a particular case of the so-called Schmincke lymphoepithelioma and study of the correlation with Epstein-Barr virus].
For poorly differentiated rhinopharyngeal carcinomas, the clinical presentation (association with the Epstein-Barr virus, paraneoplastic syndromes, onset of lymphoma) and the histopathological features can be polymorphous and they can confound or delay diagnosis and preparation of an adequate treatment plan (radio-chemotherapy). Often these neoplasms arise as clinically primitive laterocervical metastases, masked by clinical findings and a history that can lead to the mistaken diagnosis of systemic lymphoproliferative processes such as Hodgkin's disease. Here an observation of this type is presented in a young patient (19 years old) who came under observation for a laterocervical tumefaction recurrent from a previous exeresis performed at another hospital and symptoms of serotine febricula, dysphagia and serology positive for the Epstein-Barr virus (EBV). The patient underwent surgery and then radiotherapy and has been under close post-operative follow-up for two years. To date the patient's condition--both local and general--is good. The particular histology of the neoformation lies in the abundant infiltration of plasma cell and lymphocyte eosinophils, at times in blastic form. Moreover, elements with a large clear nucleus and evident nucleolus (Hodgkin-like) and scattered multinucleate Langhans-type giant cells can be seen. Immunohistologically the tumor cells markedly express for cytokeratin and the latent membrane protein (LMP1) of the Epstein-Barr virus (EBV) and show a high growth fraction. Under the electron microscope, the plurinucleate giant cells present large nuclei with morphology similar to that of tumor cells. The clear cytokeratin-positivity of the tumor elements and the histological and ultrastructural features mentioned led to the diagnosis of a massive metastasis from lymphoepithelial carcinoma, the Schmincke variant, plus EBV infection of the neoplastic cells. The authors conclude assuming that the particular granulomatous reaction is due to the host's reaction to the tumor cells, but also to the reaction to the viral antigens. In the former case we find an attempt to limit the carcinomatous process; in the latter it is a response caused by the EBV and is not, apparently, aimed at protecting against the neoplasm rather it facilitates the neoplastic process.
Adult↗
Potassium and sodium binding to the outer mouth of the K+ channel.
Molecular dynamics simulations of the K+ channel from Streptomyces lividans (KcsA channel) were performed in a membrane-mimetic environment with Na+ and K+ in different initial locations. The structure of the channel remained stable and well preserved for simulations lasting up to 1.5 ns. Salt bridges between Asp80 and Arg89 of neighboring subunits, not detected in the X-ray structure, enhanced the stability of the tetrameric structure. Na+ or K+ ions located in the channel vestibule lost part of their hydration shell and diffused into the channel inner pore in less than a few hundred picoseconds. This powerful catalytic action was caused by strong electrostatic interactions with Asp80 and Glu71. The hydration state of the metal ions turned out to depend significantly on the conformational flexibility of the channel. Furthermore, Na+ entered the channel inner pore bound to more water molecules than K+. The different hydration state of the two ions may be a determinant factor in the ion selectivity of the channel.
Binding Sites↗
Molecular epidemiology of HIV type 1 isolates from the Czech Republic: identification of an env E subtype case.
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Adolescent↗
Physical origin of selectivity in ionic channels of biological membranes.
This paper shows that the selectivity properties of monovalent cation channels found in biological membranes can originate simply from geometrical properties of the inner core of the channel without any critical contribution from electrostatic interactions between the permeating ions and charged or polar groups. By using well-known techniques of statistical mechanics, such as the Langevin equations and Kramer theory of reaction rates, a theoretical equation is provided relating the permeability ratio PB/PA between ions A and B to simple physical properties, such as channel geometry, thermodynamics of ion hydration, and electrostatic interactions between the ion and charged (or polar) groups. Diffusive corrections and recrossing rates are also considered and evaluated. It is shown that the selectivity found in usual K+, gramicidin, Na+, cyclic nucleotide gated, and end plate channels can be explained also in the absence of any charged or polar group. If these groups are present, they significantly change the permeability ratio only if the ion at the selectivity filter is in van der Waals contact with them, otherwise these groups simply affect the channel conductance, lowering the free energy barrier of the same amount for the two ions, thus explaining why single channel conductance, as it is experimentally observed, can be very different in channels sharing the same selectivity sequence. The proposed theory also provides an estimate of channel minimum radius for K+, gramicidin, Na+, and cyclic nucleotide gated channels.
Biophysical Phenomena↗
Cyclic nucleotide-gated channels. Pore topology studied through the accessibility of reporter cysteines.
In voltage- and cyclic nucleotide-gated ion channels, the amino-acid loop that connects the S5 and S6 transmembrane domains, is a major component of the channel pore. It determines ion selectivity and participates in gating. In the alpha subunit of cyclic nucleotide-gated channels from bovine rod, the pore loop is formed by the residues R345-S371, here called R1-S27. These 24 residues were mutated one by one into a cysteine. Mutant channels were expressed in Xenopus laevis oocytes and currents were recorded from excised membrane patches. The accessibility of the substituted cysteines from both sides of the plasma membrane was tested with the thiol-specific reagents 2-aminoethyl methanethiosulfonate (MTSEA) and [2-(trimethylammonium)ethyl]methanethiosulfonate (MTSET). Residues V4C, T20C, and P22C were accessible to MTSET only from the external side of the plasma membrane, and to MTSEA from both sides of the plasma membrane. The effect of MTSEA applied to the inner side of T20C and P22C was prevented by adding 10 mM cysteine to the external side of the plasma membrane. W9C was accessible to MTSET from the internal side only. L7C residue was accessible to internal MTSET, but the inhibition was partial, approximately 50% when the MTS compound was applied in the absence of cGMP and 25% when it was applied in the presence of cGMP, suggesting that this residue is not located inside the pore lumen and that it changes its position during gating. Currents from T15C and T16C mutants were rapidly potentiated by intracellular MTSET. In T16C, a slower partial inhibition took place after the initial potentiation. Current from I17C progressively decayed in inside-out patches. The rundown was accelerated by inwardly applied MTSET. The accessibility results of MTSET indicate a well-defined topology of the channel pore in which residues between L7 and I17 are inwardly accessible, residue G18 and E19 form the narrowest section of the pore, and T20, P21, P22 and V4 are outwardly accessible.
Amino Acid Sequence↗
Properties of the evoked spatio-temporal electrical activity in neuronal assemblies.
Properties of neural computation were studied in two types of neuronal networks: isolated leech ganglia and neuronal cultures of dissociated cortical neurons from neonatal rats. With appropriate experimental set-ups it was possible to obtain a precise description of the spread of excitation induced by specific inputs. The evoked spatio-temporal electrical activity was characterized by large variability and the electrical activity of neurons activated by the same stimulation was found to be statistically independent to a high degree. The variability presumably originates from basic properties of synaptic transmission, which is stochastic in nature. As a consequence, the large variability of the evoked spatio-temporal electrical activity appears to be a general property of neural computation and a typical feature of neuronal assemblies. It is shown, however, that the observed statistical independence of co-activated neurons may be used to reduce the effects of variability by appropriately averaging or pooling the electrical activity.
Animals↗
[Benign extracranial cervical-facial schwannomas: anatomo-clinical and diagnostic considerations on our case reports and review of literature].
Schwannoma is a rare neoplasm in the E.N.T. areas although it is characteristic of this discipline. Indeed, examination of the most recent data in the literature shows that approximately 45% of all neoplasms of the peripheral nerve linings occur in the head and neck district, the most common neurogenic tumors are schwannomas and these constitute 35% of all head and neck tumors. In reviewing the literature attention was focused on schwannomas originating in unusual sites, neglecting the most common sites originating in the eighth and seventh pair of cranial nerves. It was seen that the site of origin and clinical manifestation of these lesions varies widely and the four cases presented here are no exception. These are four schwannomas which came under observation between 1994 and 1997. The sites of origin were, respectively: the floor of the mouth, the submandibular region (corresponding to the Warthon duct), the anterior wall of the external auditory canal and the hypopharynx (corresponding to the pyriform sinus). All of these cases proved quite rare in the literature. All the cases underwent accurate anatomopathological examination and the paper discusses the particular histological and immunohistochemical features encountered. Reference is also made to the problems of differential diagnosis vs. other types of soft tissue tumors. Emphasis is placed on the demonstrated difficulty in recognizing schwannomas from the macroscopic and surgical points of view. The absence of mitoses, necroses, invasiveness and specific features--i.e. hyperchromia and pleomorphism of the nuclei or the presence of large atypical cells--are all parameters confirming that the lesions observed in the present study were benign. No anatompathological features were observed that could justify any particular expression of the schwannoma in the specific sites involved. Nevertheless, the authors present these case because a review of the literature indicated that they are extremely rare and because differential diagnosis of these unusual manifestations is so complex.
Adult↗
Single-channel properties of ionic channels gated by cyclic nucleotides.
This paper presents an extensive analysis of single-channel properties of cyclic nucleotide gated (CNG) channels, obtained by injecting into Xenopus laevis oocytes the mRNA encoding for the alpha and beta subunits from bovine rods. When the alpha and beta subunits of the CNG channel are coexpressed, at least three types of channels with different properties are observed. One type of channel has well-resolved, multiple conductive levels at negative voltages, but not at positive voltages. The other two types of channel are characterized by flickering openings, but are distinguished because they have a low and a high conductance. The alpha subunit of CNG channels has a well-defined conductance of about 28 pS, but multiple conductive levels are observed in mutant channels E363D and T364M. The conductance of these open states is modulated by protons and the membrane voltage, and has an activation energy around 44 kJ/mol. The relative probability of occupying any of these open states is independent of the cGMP concentration, but depends on extracellular protons. The open probability in the presence of saturating cGMP was 0.78, 0.47, 0.5, and 0.007 in the w.t. and mutants E363D, T364M, and E363G, and its dependence on temperature indicates that the thermodynamics of the transition between the closed and open state is also affected by mutations in the pore region. These results suggest that CNG channels have different conductive levels, leading to the existence of multiple open states in homomeric channels and to the flickering behavior in heteromeric channels, and that the pore is an essential part of the gating of CNG channels.
Amino Acid Sequence↗
Time-dependent current decline in cyclic GMP-gated bovine channels caused by point mutations in the pore region expressed in Xenopus oocytes.
1. Amino acids with a charged or a polar residue in the putative pore region, between lysine 346 and glutamate 372 of the alpha-subunit of the cGMP-gated channel from bovine rods were mutated to a different amino acid. The mRNA encoding for the wild-type, i.e. the alpha-subunit, or mutant channels was injected in Xenopus laevis oocytes. 2. When glutamate 363 was mutated to asparagine, serine or alanine, the current activated by a steady cGMP concentration declined in mutant channels. No current decline was observed when glutamate 363 was mutated to aspartate, glutamine or glycine, when theronine 359, 360 and 364 were mutated to alanine or when other charged residues in the pore region were neutralized. 3. The amount of current decline and its time course were significantly voltage dependent. In mutant E363A the current decline developed within about 1.5 s at -100 mV, but in about 6 s at +100 mV. In the same mutant, the current declined to about 55% of its initial level at +100 mV and to about 10% at -100 mV. 4. The current decline in mutants E363A, E363S and E363N was only moderately dependent on the cGMP concentration (from 10 to 1000 microM) and was not caused by a reduced affinity of the mutant channels for cGMP. Analysis of current fluctuations at a single-channel level indicated that current decline was primarily caused by a decrease of the open probability. 5. The wild-type channel was not permeable to dimethylammonium. When glutamate 363 was replaced by a smaller residue such as serine, mutant channels became permeable to dimethylammonium. 6. The current decline observed in mutant channels is reminiscent of desensitization of ligand-gated channels and of inactivation of voltage-gated channels. These results suggest also that gating and permeation through the cGMP-gated channel from bovine rods are intrinsically coupled and that glutamate 363 is part of the molecular structure controlling both the gating and the narrowest region of the pore.
Amino Acid Sequence↗
CCD imaging of the electrical activity in the leech nervous system.
A single ganglion of the nervous system of the leech Hirudo medicinalis was isolated. One or both roots emerging from each side of the ganglion were sucked into suction pipettes used either for extracellular stimulation or for recording the gross electrical activity. The ganglion was stained with the fluorescence voltage sensitive dye Di-4-Anepps. The fluorescence was measured with a nitrogen cooled CCD camera. Our recording system allowed us to measure in real time slow optical signals corresponding to changes in light intensity of at least 5/1000. These signals were caused by the direct polarization of neuronal structures, the afterhyperpolarization or the afterdischarge induced by a prolonged stimulation. When images were acquired at fixed times, several of them could be averaged and optical signals of at least 2/1000 could be reliably measured. These optical signals originated from well identified neurons, such as T, P and N sensory neurons. By taking images at different times and at different focal planes, electrical events could be followed at a temporal resolution of 50 Hz. The three dimensional dynamics of electrical events, initiated by a specific stimulation, was imaged and the spread of excitation among leech neurons was followed. When two roots were selectively stimulated, their neuronal interactions could be imaged and the linear and non-linear terms of the interaction could be characterized.
Animals↗
Effect of changing temperature on the ionic permeation through the cyclic GMP-gated channel from vertebrate photoreceptors.
Native cGMP-gated channels were studied in rod outer segments of the larval tiger salamander Ambystoma tigrinum. The alpha subunit of the cGMP-gated channel from bovine rods, here referred to as the wild type (w.t.), and mutant channels were heterologously expressed in Xenopus laevis oocytes. These channels were studied in excised membrane patches in the inside-out configuration and were activated by the addition of 100 or 500 microM cGMP. The effect of temperature on the ionic permeation was studied. The macroscopic current flowing through the native channel at +100 mV had an activation energy of 35.8, 30, 31.8, 34.5, 41.3, and 22.4 kJ mol-1 in the presence of Li+, Na+, K+, Rb+, Cs+, and NH4+, respectively. The macroscopic current flowing through the w.t. channel at +100 mV had an activation energy of 45.2, 38.2, 37.5, 47.3, 49.4, and 38.9 kJ mol-1 in the presence of Li+, Na+, K+, Rb+, Cs+, and NH4+, respectively. The activation energy of the macroscopic current flowing through the native and w.t. channels did not vary significantly when the ionic concentration of the permeant ion was changed between 2.5 and 110 mM. The activation energy of the single-channel current of the w.t. channel at +100 mV was 40.4 and 33 kJ mol-1 for Na+ and NH4+, respectively. The reversal potential of biionic solutions changed significantly with temperature. These results can be used to obtain an estimate of the enthalpic and entropic contributions to the barrier of the Gibbs free energy experienced by an ion during its permeation through the open channel. These estimates indicate that the ionic permeation and selectivity of the cGMP-gated channel are controlled both by enthalpic and entropic factors and that the selectivity of the native channel for Li+ over Na+ is primarily caused by entropic effects.
Ambystoma↗
The multi-ion nature of the cGMP-gated channel from vertebrate rods.
1. Native cGMP-gated channels were studied in rod outer segments of the larval tiger salamander, Ambystoma tigrinum. The alpha-subunit of the cGMP-gated channel, here referred to as the wild type (WT), and mutant channels were heterologously expressed in Xenopus laevis oocytes. These channels were studied in excised membrane patches in the inside-out configuration and were activated by the addition of 100 or 500 microM cGMP. The current carried by monovalent cations was measured under voltage-clamp conditions. 2. In the presence of 110 mM Na+ in the extracellular medium and different amounts of Na+ in the intracellular medium, the I-V relations of the native channel could be described by a single-site model with a profile of Gibbs free energy with two barriers and a well. A similar result was obtained in the presence of 110 mM Li+ in the extracellular medium and different amounts of Li+ in the intracellular medium. The well depth was 1.4RT (where R is the gas constant and T is the absolute temperature) for both Li+ and Na+. 3. The I-V relations of the native channel in the presence of 110 mM Na+ on one side of the membrane and 110 mM Li+ on the other side could not be described by the same single-site model with identical values of barriers and well obtained in the presence of Li+ or Na+ alone: the well for Li+ had to be at least 4RT. 4. In the presence of mixtures of 110 mM Li+ and Cs+ on the cytoplasmic side of the membrane, an anomalous mole fraction effect was observed both in the native and the WT channel. No anomalous behaviour was seen in the presence of Li(+)-Na+ and Li(+)-NH4+ mixtures. 5. The anomalous mole fraction effect with mixtures of Li+ and Cs+ was not observed in the channel where glutamate 363 was mutated to a glutamine (E363Q) or an asparagine (E363N). When glutamate 363 was mutated to an aspartate (E363D), the anomalous mole fraction effect with mixtures of Li+ and Cs+ was still observed, although significantly reduced. 6. When lysine 346, arginine 369, aspartate 370 and glutamate 372 were neutralized by mutation to glutamine, the ion permeation through the mutant channels and the WT channel had largely similar properties.(ABSTRACT TRUNCATED AT 400 WORDS)
Ambystoma↗