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M Venturi

Publications and source records attributed to M Venturi.

At least 19 recordsLinked to original sources
PubMed2003

A preliminary analysis of the morphology of lateral canals after root canal filling using a tooth-clearing technique.

AIM: This study used a modified tooth-clearing technique to allow observation of accessory canals following filling with a warm gutta-percha technique and one of two endodontic cements. METHODOLOGY: Ten extracted human maxillary molars with three roots were selected and divided into two equal groups of five teeth. Each group had 15 canals. Root canal preparation was performed with a modified double flared technique; irrigation with 5% NaOCl and lubrication with RC-Prep were used. The canals were then filled with gutta-percha and cement utilizing a warm vertical condensation technique in the apical third followed by thermo-mechanical compaction in the middle and coronal thirds. Pulp Canal Sealer or AH-Plus were used in the experimental groups. The teeth were demineralized with a modified buffered acid solution, cleared in methylsalicylate and examined under a stereomicroscope. Accessory canals were evaluated in the apical, middle and coronal thirds of each root canal and categorized as narrow or wide, following observation on four surfaces. The depth of penetration of gutta-percha and cement into lateral canals was scored using a 5-point system. RESULTS: Complete transparency of the roots was achieved. Accessory canals were detected in all specimens. In coronal ramifications, gutta-percha filled the empty spaces (coronal thirds, grades 3 and 4: 70.9% in AH-Plus group and 68.8% in Pulp Canal Sealer group). In the apical accessory canals, gutta-percha entered less frequently (apical thirds, grades 3 and 4: 17.9% in the AH-Plus group and 3.2% in the Pulp Canal Sealer group); cement without gutta-percha (grades 1 and 2) was present in 55.5% in the AH-Plus group and 38.7% of the Pulp Canal Sealer group. Analysis showed that AH-Plus cement resulted in significantly greater filling of the apical accessory canals compared to Pulp Canal Sealer. CONCLUSIONS: The modified tooth-clearing technique allowed observation of fine morphological details in all specimens. Effective gutta-percha filling was evident in most of the wide coronal lateral canals whilst the apical narrow ramifications were often incompletely filled by cement. Overall AH-Plus demonstrated better diffusion into lateral accessory canals compared to Pulp Canal Sealer.

Citrates↗
PubMed2002

Temperature change within gutta-percha induced by the System-B Heat Source.

AIM: This study evaluated the temperature change within gutta-percha during the vertical compaction technique performed with a System-B Heat Source. METHODOLOGY: Extracted human teeth were prepared and divided in two equal groups depending on the apex diameter (group 1: 0.20-0.25 mm and group 2: 0.30-0.35 mm). Teeth were root treated with a combination of step-back and coronal flaring instrumentation using Gates Glidden burs and hand stainless steel K- and H-files. Two thermocouples were connected to the outer surface of the root: the first one was placed 2 mm apically from cement-enamel junction (CEJ) (point C); and the second one 1.5 mm from the apex (point A). The instrumented canals were filled with size F gutta-percha cones. All teeth were then immersed in a thermostatic bath at a constant temperature of 37 degrees C and warm vertical compaction was performed using a System-B Heat Source. delta T values were recorded by means of a digital thermometer connected to the thermocouples. RESULTS: Increments of temperature (delta T) recorded in point A revealed a mean value of 0.5 +/- 0.5 degree C for group 1 and 0.9 +/- 1.1 degrees C for group 2; delta T values recorded at point C gave a mean value of 4.1 +/- 1.7 degrees C for group 1 and 3.9 +/- 1.81 degrees C in group 2. No statistical difference was found between the groups, whilst a difference was present between the measurements at points A and C (P < 0.01). CONCLUSIONS: The use of the System-B Heat Source on root canals maintained at a constant body temperature by a thermostatic bath revealed that the increase of temperature of the gutta-percha at the apical third of the canal was negligible and that the compaction of the mass of the gutta-percha close to the apex was performed at body temperature. Minor changes in temperature of the outer surface of the root canals occurred, suggesting no danger for the periradicular tissues.

Analysis of Variance↗
PubMed2002

Selection criteria and long-term results of surgery in symptomatic rectocele.

BACKGROUND: The aim of this study was to confirm some selection criteria for the transrectal repair of the anterior rectocele and to compare our surgical results with those reported in the literature. METHODS: From January 1992 to December 1999, 30 females (mean age 52.9 years, range 28-70 yrs) affected by anterior rectocele were prospectively evaluated with a standard questionnaire, clinical examination, proctosigmoidoscopy, colonic transit time, dynamic defecography, anal EMG, anal manometry. Then, they were submitted to transrectal repair of rectocele with anterior plication of the rectal muscular wall. Fourteen (46.6%) of them were also submitted to perineal levatorplasty. Patients were followed postoperatively (mean 25.7 months) with the same standard questionnaire, clinical examination, defecography, and manometry. Results were tested by Fisher's Exact text, Wilcoxon's test, and "t"-test. RESULTS: Rectal dyschezia, incomplete evacuation, digital help in defecating, mean stool frequency, and rectal bleeding significantly improved. After 3 months, 30% of patients had no complaints, 40% had only 1-2 episodes/month complaints, 13.3% had evacuation only using laxatives, and 16.6% were unchanged. Defecography showed a significant reduction of the rectocele in 70% of patients after 3 months. Manometric parameters were not significantly modified. Four (28.6%) out of 14 patients submitted to perineal levatorplasty complained of dyspareunia. CONCLUSIONS: Our surgical results were comparable with those reported in the literature, with more than 80% of successful outcome. Preoperative clinical data and defecography were confirmed to be basic parameters in selecting patients for surgery. Colonic transit time, anal EMG, and anorectal manometry demonstrated to be useful to recognize conditions as slow colonic transit time, peripheral denervation, and reduced voluntary contraction that could lead to a less satisfactory outcome after surgery, and might benefit with a postoperative perineal rehabilitation by biofeedback and anal electrostimulations. The perineal levatorplasty is not suitable in young females, due to the risk of dyspareunia.

Adult↗
PubMed2001

Dual-mode "co-conformational" switching in catenanes incorporating bipyridinium and dialkylammonium recognition sites.

Three [2]catenanes and three [3]catenanes incorporating one or two pi-electron-rich macrocyclic polyethers and one pi-electron-deficient polycationic cyclophane have been synthesized in yields ranging from 4 to 38%. The pi-electron-rich macrocyclic components possess either two 1,4-dioxybenzene or two 1.5-dioxynaphthalene recognition sites. The pi-electron-deficient cyclophane components incorporate two bipyridinium and either one or two dialkylammonium recognition sites. The template-directed syntheses of these catenanes rely on i) pi...pi stacking interactions between the dioxyarene and bipyridinium recognition sites, ii) C-H...O hydrogen bonds between some of the bipyridinium hydrogen atoms and some of the polyether oxygen atoms, and iii) C-H...pi interactions between some of the dioxyarene hydrogen atoms and the aromatic spacers separating the bipyridinium units. The six catenanes were characterized by mass spectrometry and by both 1H and 13C NMR spectroscopy. The absorption spectra and the electrochemical properties of the catenanes have been investigated and compared with those exhibited by the component macrocycles and by related known catenanes. Broad and weak absorption bands in the visible region, originating from charge-transfer (CT) interactions between electron-donor and electron-acceptor units, have been observed. Such charge-transfer interactions are responsible for the quenching of the potentially fluorescent excited states of the aromatic units of the macrocyclic polyether components. The redox behavior of these novel compounds has been investigated and correlations among the observed redox potentials are illustrated and discussed. The catenanes undergo co-conformational switching upon one-electron reduction of the two bipyridinium units. One of them--in its reduced form--can be also switched by acid/base inputs and exhibits AND logic behavior. The co-conformational rearrangements induced by the redox and acid/base stimulations lend themselves to exploitation in the development of molecular-level machines and logic gates.

Journal Article↗
PubMed2001

Na(+)/H(+) antiporters.

Na(+)/H(+) antiporters are membrane proteins that play a major role in pH and Na(+) homeostasis of cells throughout the biological kingdom, from bacteria to humans and higher plants. The emerging genomic sequence projects already have started to reveal that the Na(+)/H(+) antiporters cluster in several families. Structure and function studies of a purified antiporter protein have as yet been conducted mainly with NhaA, the key Na(+)/H(+) antiporter of Escherichia coli. This antiporter has been overexpressed, purified and reconstituted in a functional form in proteoliposomes. It has recently been crystallized in both 3D as well as 2D crystals. The NhaA 2D crystals were analyzed by cryoelectron microscopy and a density map at 4 A resolution was obtained and a 3D map was reconstructed. NhaA is shown to exist in the 2D crystals as a dimer of monomers each composed of 12 transmembrane segments with an asymmetric helix packing. This is the first insight into the structure of a polytopic membrane protein. Many Na(+)/H(+) antiporters are characterized by very dramatic sensitivity to pH, a property that corroborates their role in pH homeostasis. The molecular mechanism underlying this pH sensitivity has been studied in NhaA. Amino acid residues involved in the pH response have been identified. Conformational changes transducing the pH change into a change in activity were found in loop VIII-IX and at the N-terminus by probing trypsin digestion or binding of a specific monoclonal antibody respectively. Regulation by pH of the eukaryotic Na(+)/H(+) antiporters involves an intricate signal transduction pathway (recently reviewed by Yun et al., Am. J. Physiol. 269 (1995) G1-G11). The transcription of NhaA has been shown to be regulated by a novel Na(+)-specific regulatory network. It is envisaged that interdisciplinary approaches combining structure, molecular and cell biology as well as genomics should be applied in the future to the study of this important group of transporters.

Amino Acid Sequence↗
PubMed2001

Oligomerization of NhaA, the Na+/H+ antiporter of Escherichia coli in the membrane and its functional and structural consequences.

Recently, a two-dimensional crystal structure of NhaA, the Na+/H+ antiporter of Escherichia coli has been obtained [Williams, K. A., Kaufer, U. G., Padan, E., Schuldiner, S. and Kühlbrandt, W. (1999) EMBO J., 18, 3558-3563]. In these crystals NhaA exists as a dimer. Using biochemical and genetic approaches here we show that NhaA exists in the native membrane as a homooligomer. Functional complementation between the polypeptides of NhaA was demonstrated by coexpression of pairs of conditional lethal (at high pH in the presence of Na+) mutant alleles of nhaA in EP432, a strain lacking antiporters. Physical interaction in the membrane was shown between the His-tagged NhaA polypeptide which is readily affinity purified from DM-solubilized membranes with a Ni2+-NTA column and another which is not; only when coexpressed did both copurify on the column. The organization of the oligomer in the membrane was studied in situ by site-directed cross-linking experiments. Cysteine residues were introduced--one per NhaA--into certain loops of Cys-less NhaA, so that only intermolecular cross-linking could take place. Different linker-size cross-linkers were applied to the membranes, and the amount of the cross-linked protein was analyzed by mobility shift on SDS-PAGE. The results are consistent with homooligomeric NhaA and the location of residue 254 in the interface between monomers. Intermolecular cross-linking of V254C caused an acidic shift in the pH profile of NhaA.

Alleles↗
PubMed2001

Which surgical approach for rectocele? A multicentric report from Italian coloproctologists.

The most effective surgical technique for rectocele has not yet been clearly established. A retrospective multicentric study was carried out to compare the long-term results of 3 endorectal techniques (Block, Sarles and stapled) and the perineal levatorplasty, alone and in association, in a series of patients with symptomatic rectocele. From January 1992 to December 1999, 2212 patients with defecation disorders were referred to 5 Italian coloproctology units. An anterior rectocele was clinically diagnosed in 1045 patients and confirmed with defecography. On the basis of clinical and radiological parameters, 317 patients (312 women; mean age, 52.4+/-20.1 years) were selected for surgery. Group 1 consisted of 141 patients (136 women; mean age, 50.4+/-18.8 years) who were submitted to endorectal operations. Group 2 consisted of 126 women (mean age, 52.5+/-19.7 years) who received perineal levatorplasty. Finally, 50 women (mean age, 54.3+/-21.9 years) in Group 3 received endorectal operations associated with perineal levatorplasty. A total of 269 patients were followed postoperatively (mean period, 24.2+/-3.1 months, 27.5+/-5.4 months and, 22.8+/-2.8 months, respectively) with the same questionnaire and clinical examination. Three months after surgery, a defecography examination and anorectal manometry were performed in 136 and 132 patients, respectively. Operative time, hospital stay and time to return to work were significantly higher in Group 3 (p<0.001). There was one death in Group 3 due to severe sepsis. Main postoperative complications were: in Group 1, hemorrhage (7.8%, all Sarles), dehiscence of the endorectal suture (5.0%, all Block), distal rectal stenosis (2.1%, 1 stapled, 2 block), and rectovaginal fistula (1.4%, all Sarles); in Group 2, delayed healing of the perineal wound (16.4%); in Group 3 delayed healing of the perineal wound (22.0%), hemorrhage (6%, all Sarles), dehiscence (4.0%), stenosis (2.0%). 17.3% of patients of Group 2 and 22.5% of Group 3 complained of dyspareunia. Postoperative defecography showed a complete absence of the rectocele in 44.1% of patients and reduction of size in the others, without significant differences among the three groups. Manometric pattern was not significantly modified by surgery. Significant symptoms recurred in 5.9% of the patients in Group 1, 6.4% in Group 2, and 5.0% in Group 3. Perineal levatorplasty did not significantly improve obstructed defecation, as it did not allow to excise the rectal mucosal prolapse, and was followed by an high incidence of delayed healing of the perineal wound and dyspareunia. Sarles procedure achieved better control of mucosal prolapse but carried a higher complication rate compared to the others. The association of the perineal levatorplasty with an endorectal technique required significantly longer operative time, and led to a longer hospital stay and time to return to work. In conclusion, the investigated techniques showed different patterns of postoperative complications: bleeding after Sarles, dehiscence after Block, dyspareunia after perineoplasty and fatal gangrene after stapled, but non of them showed a clear superiority over the others in term of clinical or functional results 2 years after surgery.

Adult↗
PubMed2001

Randomised controlled trial between stapled circumferential mucosectomy and conventional circular hemorrhoidectomy in advanced hemorrhoids with external mucosal prolapse.

BACKGROUND: This randomized prospective study compared the outcome of circular hemorrhoidectomy according to the Hospital Leopold Bellan (HLB) technique (Paris) with Longo stapled circumferential mucosectomy (LSCM) in two homogeneous groups of patients affected by circular fourth-degree hemorrhoids with external mucosal prolapse. METHODS: From December 1996 to December 1999, 80 consecutive patients with fourth-degree hemorrhoids and external mucosal prolapse were randomly assigned to two groups. Forty patients (group A: 18 men, 22 women, mean age 50.5 years, range 21 to 82) underwent HLB hemorrhoidectomy, and 40 patients (group B: 15 men, 25 women, mean age 51.0 years, range 29 to 92) underwent LSCM. Before surgery, all patients were selected with a standard questionnaire for symptom evaluation, full proctological examination, flexible rectosigmoidoscopy, dynamic defecography, and anorectal manometry. No significant differences among the two groups were found. All patients were controlled with follow-up questionnaire and with clinical examination at 1, 2, 4, 12, and 54 weeks after the operation. A postoperative manometry was performed 3 months after surgery. RESULTS: The length of the operation was significantly lower in group B (25 +/- 3.1 SD versus 50 +/- 5.3 minutes, P <0.001). Mean hospital stay was 3 +/- 0.4 days in group A and 2 +/- 0.5 days in group B (P <0.01). Mean duration of inability to work was 8 +/- 0.9 days in group B and 15 +/- 1.4 days in group A (P <0.001). Postoperative pain was significantly lower in group B (P <0.001). Mean length of follow-up was 20 +/- 8.0 months in group A and 20 +/- 7.8 months in group B. Late complications were similar in the two groups, with 0%, at present, recurrence rate. CONCLUSIONS: Our results confirm that both operations are safe, easy to perform, and effective in the treatment of advanced hemorrhoids with external mucosal prolapse. However, the LSCM seems to be preferable owing to the fewer postoperative complications, easier postoperative management, and shorter time to return to work. A longer follow-up is required to confirm the true efficacy of this surgical method.

Adult↗
PubMed2001

Artificial molecular-level machines: which energy to make them work?

The concept of machine can be extended to the molecular level by designing and synthesizing (supra)molecular species capable of performing mechanical movements. The energy needed to make a machine work can be supplied as chemical energy, electrical energy, or light. When a chemical "fuel" is used, waste products are formed, whereas this is not the case when suitable photochemical or electrochemical energy inputs are employed. A number of elementary functions performed by molecular-level machines are illustrated, and more complex ones are foreseen.

Electrochemistry↗
PubMed2000

A photochemically driven molecular-level abacus

A molecular-level abacus-like system driven by light inputs has been designed in the form of a [2]rotaxane, comprising the pi-electron-donating macrocyclic polyether bis-p-phenylene-34-crown-10 (BPP34C10) and a dumbbell-shaped component that contains 1) a Ru(II) polypyridine complex as one of its stoppers in the form of a photoactive unit, 2) a p-terphenyl-type ring system as a rigid spacer, 3) a 4,4'-bipyridinium unit and a 3,3'-dimethyl-4,4'-bipyridinium unit as pi-electron-accepting stations, and 4) a tetraarylmethane group as the second stopper. The synthesis of the [2]rotaxane was accomplished in four successive stages. First of all, the dumbbell-shaped component of the [2]rotaxane was constructed by using conventional synthetic methodology to make 1) the so-called "west-side" comprised of the Ru(II) polypyridine complex linked by a bismethylene spacer to the p-terphenyl-type ring system terminated by a benzylic bromomethyl function and 2) the so-called "east-side" comprised of the tetraarylmethane group, attached by a polyether linkage to the bipyridinium unit, itself joined in turn by a trismethylene spacer to an incipient 3,3'-dimethyl-4,4'-bipyridinium unit. Next, 3) the "west-side" and "east-side" were fused together by means of an alkylation to give the dumbbell-shaped compound, which was 4) finally subjected to a thermodynamically driven slippage reaction, with BPP34C10 as the ring, to afford the [2]rotaxane. The structure of this interlocked molecular compound was characterized by mass spectrometry and NMR spectroscopy, which also established, along with cyclic voltammetry, the co-conformational behavior of the molecular shuttle. The stable translational isomer is the one in which the BPP34C10 component encircles the 4,4'-bipyridinium unit, in keeping with the fact that this station is a better pi-electron acceptor than the other station. This observation raises the question- can the BPP34C10 macrocycle be made to shuttle between the two stations by a sequence of photoinduced electron transfer processes? In order to find an answer to this question, the electrochemical, photophysical, and photochemical (under continuous and pulsed excitation) properties of the [2]rotaxane, its dumbbell-shaped component, and some model compounds containing electro- and photoactive units have been investigated. In an attempt to obtain the photoinduced abacus-like movement of the BPP34C10 macrocycle between the two stations, two strategies have been employed-one was based fully on processes that involved only the rotaxane components (intramolecular mechanism), while the other one required the help of external reactants (sacrificial mechanism). Both mechanisms imply a sequence of four steps (destabilization of the stable translational isomer, macrocyclic ring displacement, electronic reset, and nuclear reset) that have to compete with energy-wasteful steps. The results have demonstrated that photochemically driven switching can be performed successfully by the sacrificial mechanism, whereas, in the case of the intramolecular mechanism, it would appear that the electronic reset of the system is faster than the ring displacement.

Journal Article↗
PubMed2000

The electrochemically-driven decomplexation/recomplexation of inclusion adducts of ferrocene derivatives with an electron-accepting receptor

The tetracationic cyclophane, cyclobis(paraquat-4,4'-biphenylene), binds 1,1'-disubstituted ferrocene-based polyethers as a result of (i) [pi...pi] stacking between the pi-electron-deficient bipyridinium units and the pi-electron-rich cyclopentadienyl rings and (ii) [C-H...O] hydrogen bonds between the alpha-bipyridinium hydrogen atoms and the polyether oxygen atoms. However, even the presence of a bulky tetraarylmethane group--which is too large to thread through the cavity of the cyclophane host--at the end of each of the two polyether substituents of the ferrocene-containing guest does not discourage adduct formation of the inclusion type. Thus, in these adducts, the ferrocene unit of the guest is located inside the cavity of the host with its two polyether chains protruding outward from the same side of the host. The alternative pseudorotaxane geometry is not observed in solutions of these 1:1 adducts. The host-guest adducts display absorption bands in the visible spectral region, characteristic of charge-transfer interactions. In the case of one of these adducts, reversible decomplexation/recomplexation takes place upon electrochemical oxidation/reduction of the ferrocene-based unit or upon reduction/oxidation of the tetracationic cyclophane.

Journal Article↗
PubMed2000

Switching of pseudorotaxanes and catenanes incorporating a tetrathiafulvalene unit by redox and chemical inputs

An acyclic polyether 1a, incorporating a central tetrathiafulvalene (TTF) electron donor unit and two 4-tert-butylphenoxy groups at its termini, has been synthesized. Two macrocyclic polyethers containing two different electron donors, namely a TTF unit with, in one case, a 1,4-dioxybenzene ring (2a), and, in the other case (2b), a 1,5-dioxynaphthalene ring system, have also been synthesized. These two macrocyclic polyethers have been mechanically interlocked in kinetically controlled template-directed syntheses with cyclobis(paraquat-p-phenylene) cyclophane (3(4+)) to afford the [2]catenanes 2a/3(4+) and 2b/3(4+), respectively. X-ray crystallography reveals that the [2]-catenane 2b/3(4+) has the TTF unit of 2b located inside the cavity of 3(4+). The spectroscopic (UV/vis and 1H NMR) and electrochemical properties of compounds 1a, 2a, 2b, 2a/3(4+), and 2b/3(4+) and of the [2]pseudorotaxane 1a.3(4+) were investigated. The absorption and emission properties of the mono- and dioxidized forms of the TTF unit in these various species have also been studied. The results obtained in acetonitrile solution can be summarized as follows. (a) While TTF2+ exhibits a strong fluorescence, no emission can be observed for the TTF2+ units contained in the polyethers and in their pseudorotaxanes and catenanes. (b) A donor-acceptor absorption band is observed upon two-electron oxidation of the TTF unit in the macrocyclic polyethers 2a and 2b. (c) The spontaneous self-assembly of 1a and 3(4+) to give the [2]pseudorotaxane 1a.3(4+) is strongly favored (Kass. = 5 x 10(5) L mol-1) but slow (at 296 K, k = 11.3 L mol-1 s-1 and delta G++ = 15.9 kcal mol-1) because of the steric hindrance associated with the bulky end groups of 1a. (d) In the pseudorotaxane 1a.3(4+), the reversible displacement of the cyclophane from the TTF unit in the threadlike substrate occurs on oxidation/reduction of its electroactive components. (e) Switching between the two translational isomers of the catenanes 2a/3(4+) and 2b/3(4+) occurs by cyclic oxidation and reduction of the TTF unit contained in 2a and in 2b, respectively. (f) Addition of o-chloroanil to the pseudorotaxane 1a.3(4+) and to the catenanes 2a/3(4+) and 2b/3(4+) causes the displacement of the TTF unit from the cavity of the cyclophane 3(4+) because of the formation of an adduct between the TTF unit and o-chloroanil.

Journal Article↗
PubMed2000

The monoclonal antibody 1F6 identifies a pH-dependent conformational change in the hydrophilic NH(2) terminus of NhaA Na(+)/H(+) antiporter of Escherichia coli.

One of the most interesting properties of the NhaA Na(+)/H(+) antiporter of Escherichia coli is the strong regulation of its activity by pH. This regulation is accompanied by a conformational change that can be probed by digestion with trypsin and involves the hydrophilic loop connecting the transmembrane helices VIII-IX. In the present work we show that a monoclonal antibody (mAb), 1F6, recognizes yet another domain of NhaA in a pH-dependent manner. This antibody binds NhaA at pH 8.5 but not at pH 4.5, whereas two other mAbs bind to NhaA independently of pH. The epitope of mAb 1F6 was located at the NH(2) terminus of NhaA by probing proteolytic fragments in Western blot analysis and amino acid sequencing. The antibody bound to the peptide HLHRFFSS, starting at the third amino acid of NhaA. A synthetic peptide with this sequence was shown to bind mAb 1F6 both at acidic and alkaline pH suggesting that this peptide is accessible to mAb 1F6 in the native protein only at alkaline pH. Although slightly shifted to acidic pH, the pH profile of the binding of mAb 1F6 to the antiporter is similar to that of both the Na(+)/H(+) antiporter activity as well as to its sensitivity to trypsin. We thus suggest that these pH profiles reflect a pH-dependent conformational change, which leads to activation of the antiporter. Indeed, a replacement of Gly-338 by Ser (G338S), which alleviates the pH dependence of both the NhaA activity as well as its sensitivity to trypsin, affects in a similar pattern the binding of mAb 1F6 to NhaA. Furthermore, the binding site of mAb 1F6 is involved in the functioning of the antiporter as follows: a double Cys replacement H3C/H5C causes an acidic shift by half a pH unit in the pH dependence of the antiporter; N-ethylmaleimide, which does not inhibit the wild-type protein, inhibits H3C/H5C antiporter to an extent similar to that exerted by mAb 1F6.

Amino Acid Sequence↗
PubMed2000

Role of iodine in evolution and carcinogenesis of thyroid, breast and stomach.

The authors have hypothesized that dietary iodine (deficiency or excess) is associated with the development of some gastric and mammary cancers, as it is well-known for thyroid cancer. They report a short review of their own work and of the general literature on this correlation and on the antioxidant function of iodide in stomach, breast and thyroid. Thyroid cells phylogenetically derived from primitive iodide-concentrating gastroenteric cells which, during evolution, migrated and specialized in uptake and storage of iodine, also in order to adapt the organisms from iodine-rich sea to iodine-deficient land. Mammary cells also derived from primitive iodide-concentrating ectoderm. Stomach, breast and thyroid share an important iodide-concentrating ability and an efficient peroxidase activity, which transfers electrons from iodides to the oxygen of hydrogen peroxide and so protects the cells from damage caused by lipid peroxidation. The authors suggest that iodide might have an ancestral antioxidant function in all iodide-concentrating cells from primitive Algae to more recent Vertebrates. In Italy, gastric cancer is more frequent in farmers and in iodine-deficient populations, living in mountainous and hilly areas, than in fishermen. In the last two decades, Italian decrease of gastric cancer seems to be correlated more to the higher dietary consumption of iodine-rich fish rather than to consumption of fruit and vegetables, which indeed has decreased in Italy.

Adult↗
PubMed1999

Surgical treatment of complete rectal prolapse: results of abdominal and perineal approaches.

This retrospective study reports the results of our 5-year experience in the diagnosis and treatment of rectal prolapse with fecal incontinence by the abdominal (laparotomy or laparoscopy) and perineal approaches. Twenty-five patients (group A; 22 women and 3 men; mean age 57.3 years; range 22-76 years) were operated on by the abdominal approach and ten (group B; 8 women and 2 men; mean age 68.9 years; range 58-84 years) by the perineal approach. All patients were evaluated by clinical examination, proctosigmoidoscopy, pancolonic transit time, dynamic defecography, anorectal manometry, and anal electromyography preparatory to surgery. In patients of group A, we performed an abdominal rectopexy in 19 cases (7 by laparoscopy) and in the remaining 6 cases, a sigmoid resection-rectopexy (3 of which were by laparoscopy). All patients of group B were treated by a perineal operation using Delorme's mucosectomy in 4 cases and Altemeier's rectosigmoidectomy with total perineoplasty in 6 cases. The mean follow-up was 38.8 months in group A and 25.7 months in group B. The postoperative complication rate was 8% (two cases) in group A, whereas no significant complications occurred in group B. Dyschezia and fecal incontinence improved significantly in both groups (P < 0.05 in group A and P < 0.005 in group B), whereas anoperineal pain was not significantly reduced. At 1-year follow-up, the recurrences rates were 8% in group A and 30% in group B. Rectopexy or resection-rectopexy proved to be a safe and effective procedure for external prolapse, without a discernible difference between the laparotomic and laparoscopic techniques. In selected cases, the perineal approach gives good results regarding fecal incontinence without complications, even if in these patients, the likelihood of recurrence is high.

Adult↗
PubMed1999

Laparotomic vs. laparoscopic rectopexy in complete rectal prolapse.

AIM: The aim of this study was to compare the functional and clinical results of laparotomic and laparoscopic rectopexy in 2 homogeneous groups of patients with complete rectal prolapse and fecal incontinence. METHODS: Between January 1989 and December 1997, twenty-three patients underwent abdominal rectopexy. Thirteen patients (group A, 12 females and 1 male, mean age 57.3, range 22-76 years), and 10 patients (group B, 10 females, mean age 52.3, range 26-70 years) were submitted respectively to either Wells laparotomic or laparoscopic rectopexy by the same surgical team using the same surgical technique and materials. Before the operation a detailed clinical history was collected, and the patients were studied by inspection and digital examination of the anorectum, proctosigmoidoscopy, pancolonic transit time, dynamic defecography, anorectal manometry and anal electromyography. After the operation all patients underwent perineal physiotherapy, external electric stimulation, and perineal biofeedback. Mean follow-up was 37.1 (range 6-90) months in group A and 25.7 (range 6-49) months in group B. Values were compared by chi(2), Mann-Whitney U, and Wilcoxon tests as appropriate. Differences were considered significant at p < 0.05. RESULTS: In both groups dyschezia and fecal incontinence improved significantly (p < 0.05) after the operation. The basal pressure of the anal sphincter, squeezing pressure and rectoanal reflex improved without significance, and anal-perineal pain was not significantly reduced. In group B the postoperative hospital stay was lower than in group A, with a reduction in costs. CONCLUSION: Laparoscopic Wells rectopexy has the same clinical and functional results as laparotomic rectopexy, but with a shorter postoperative hospital stay and lower costs.

Adult↗