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1.
Prevalence of chromosomal abnormalities in 2078 infertile couples referred for assisted reproductive techniques 总被引:2,自引:0,他引:2
Clementini E Palka C Iezzi I Stuppia L Guanciali-Franchi P Tiboni GM 《Human reproduction (Oxford, England)》2005,20(2):437-442
BACKGROUND: This study analyses the prevalence of karyotype changes and Yq11 microdeletions among couples referred for assisted reproduction techniques. METHODS: Prior to receiving either IVF or ICSI treatment, each partner of 2078 infertile couples was screened for karyotype changes by GTG-banding technique on peripheral lymphocytes. No subject presented with obvious phenotype of chromosomal rearrangement. All the oligo/azoospermic men with normal karyotype were further investigated by PCR for Yq11 microdeletions. RESULTS: Eighty-two out of 2078 couples (3.95%) had one partner carrying a chromosomal change, and 10 out of 202 (4.95%) men showed Yq11 microdeletions. The chromosomal rearrangements were 44 (2.1%) translocations, 23 (1.1%) gonosomal mosaics, six (0.3%) 47,XXY, five (0.24%) marker chromosomes, three (0.14%) inversions and one (0.05%) duplication. Frequency of anomalies in men and women were similar: 42 and 40 cases respectively. CONCLUSIONS: Partners of infertile couples requiring IVF or ICSI treatment appear to be affected by higher frequency of chromosomal rearrangements than the general population. Categories with greater risk were represented by men with sperm cell count <20 x 10(6) sperm/ml, and women with history of pregnancy loss. 相似文献
2.
3.
Liberati M Melchiorre K D'Emilio I Guanciali-Franchi PE Iezzi I Rotmensch S Celentano C 《Fetal diagnosis and therapy》2008,23(1):15-17
Pallister-Killian syndrome (PKS) is a sporadic chromosomal anomaly, caused by a tissue-specific mosaic distribution of an additional isochromosome 12p. About 60 cases of prenatal diagnosis of PKS have been reported. Only 1 case of PKS is described on the basis of prenatal screening, presenting increased nuchal translucency. An abnormal fetal facial profile is described prenatally as sonographic evidence of PKS. We report a case of prenatal diagnosis in a fetus undergoing second-level scan due to positive triple screen with ultrasound features of PKS. 相似文献
4.
Biological width formation to immediate implants placed at different level in relation to the crestal bone: an experimental study in dogs
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5.
In this study, a series of silyl-containing ethoxycarbonates and ethoxycarbamates on electron poor anilines and phenols were synthesized and their kinetics of disassembly determined in real-time upon exposure to fluoride ion sources at room temperature. The results provide a greater understanding of stability and kinetics for silyl-containing protecting groups that eliminate volatile molecules upon removal, which will allow for simplification of orthogonal protection in complex organic molecules.Rate constants of disassembly for synthesized silyl-containing ethoxycarbonyls were significantly faster than TEOC, a common protecting group.Silicon-based groups have demonstrated wide utility in organic syntheses, ranging from orthogonal protection of amine, hydroxyl and acid functionalities in complex drug molecules1–3 to utilization as a trigger in self-immolative polymers and dendrimers.4–6 One of the commonly used silicon-based protecting groups is 2-(trimethylsilyl)ethoxycarbonyl (TEOC),7 which was originally developed and later optimized for N-protection of amino acids to prevent formation of oligopeptides, but has since been utilized for protection of other functionalities.8 The uniqueness of TEOC is that it can be preferentially removed with a mild de-blocking agent, such as fluoride ion, in the presence of other base-sensitive groups to produce low molecular weight and volatile by-products via cascading bond cleavage, thereby easing purification of complex mixtures and enabling greater product yields.During our course of utilizing TEOC to protect amine and hydroxyl functionality on aliphatic oligomers we discovered there was a severe lack of kinetic data in the literature for removal of TEOC using fluoride ion, as most papers generally stated the times for removal as occurring within hours at elevated temperatures7 to days at room temperature.9,10 Furthermore, similar silyl-containing protecting groups, such as (2-phenyl-2-trimethylsilyl)ethoxycarbonyl (PSOC)11 and 2-(triphenylsilyl)ethoxycarbonyl (TPSEOC),12 were reported to be removed under milder fluoride ion conditions and/or faster times than TEOC due to a more readily formed fluoro-containing penta-coordinated intermediate as a result of phenyl group incorporation. However, while these groups were reported to be removed within minutes to hours at room temperature the studies provide minimal details on the actual kinetics compared to TEOC. As a result, we aimed to generate quantitative kinetic data for the removal of TEOC and other silyl-containing ethoxycarbonyl groups from functionality by performing disassembly experiments with fluoride ion sources at room temperature, as this information is relevant to those utilizing orthogonal protecting group chemistry in multi-step synthesis and potentially in the processing of pharmaceuticals.Herein, we report the kinetics of disassembly (i.e., rate constants (k) for removal) for a series of silyl-terminated ethoxycarbonyl protecting groups, such as TEOC, 2-(methyldiphenylsilyl)ethoxycarbonyl (MDPSEOC), and several extended chain versions of these molecules, from electron poor hydroxyl and amine functionalities. To do this, we utilized non-substituted and para-substituted phenols and anilines, as these molecules provided a UV-visible chromophore for real-time detection during removal of the protecting groups. We also synthesized and determined the kinetics of disassembly for several novel silyl-centered bis(ethoxycarbonyls), as we were interested in studying the reaction of multiple fluoride ions with silicon and their influence on the resulting kinetics.Our study of these molecules commenced by attempting to determine the rate constants of disassembly for 4-nitrophenyl (2-(trimethylsilyl)ethyl) carbonate (1a), a commercially available control,13 and synthesized 2-(trimethylsilyl)ethyl (4-nitrophenyl)carbamate (1b), using solutions of different fluoride salts in organic solvents and water. It was initially found that tetrahydrofuran (THF), dichloromethane, and acetonitrile provided good solubility of these organic molecules, with water and water/solvent combinations providing limited solubility. Furthermore, fluoride ion sources, such as tetrabutylammonium fluoride trihydrate (TBAF·3H2O) and a 1 : 1 molar ratio of TBAF/CsF, provided good solubility in the aforementioned solvents and several solvent/water combinations, whereas solubility of cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), and stannous fluoride (SnF2) were limited. It should be noted that a 1 : 1 TBAF/CsF mixture in THF provided nearly identical rate constants of disassembly during initial studies as TBAF in THF. However, to maintain fluoride ion solution consistency it was determined that all kinetic experiments would be conducted in THF using commercially available TBAF in THF.Kinetic experiments for 1a and 1b were conducted as 0.1 mM solutions in THF using 1 ml cuvettes and an Agilent 8453 UV-Visible Spectrophotometer. To initiate disassembly, 4 molar equivalents of 1.0 M TBAF in THF were added separately to 1a and 1b at room temperature (Scheme 1), then the absorbance of the solutions were recorded up to 120 minutes. The cuvettes were not stirred upon addition of the fluoride salt solution in effort to prevent an increase in the rate of disassembly due to turbidity. Silyl-terminated carbonate 1a, which has a maximum absorbance (λmax) at 270 nm, decreased within minutes as a new absorbance at λmax of 423 nm appeared, corresponding to 4-nitrophenolate (2a).14 Ethylene and carbon dioxide were detected via gas chromatography/mass spectrometry (GC-MS), thereby supporting the proposed mechanism of disassembly as shown in Scheme 1.7 The rate constant of disassembly for 1a was found to be 2196 ± 1380 M−1 min−1 for the second order reaction (15 although this peak quickly decreased as a new absorbance at λmax of 366 nm was formed. The latter corresponded to 4-nitroaniline (2c),16 the conjugate acid of 2b, and is proposed to have resulted from beta-elimination of a proton on the tetrabutylammonium cation, thereby forming tributylamine and 1-butene as side products via a Hofmann elimination.171H-NMR and GC-MS analysis of the solution after disassembly supports this hypothesis. The rate constant of disassembly for 1b was determined to be 38.5 ± 0.3 M−1 min−1, and the slower rate compared to 1a is consistent with substituted anilines possessing a larger pKa value than substituted phenols. 2-(methyldiphenylsilyl)ethyl (4-nitrophenyl) carbonate 1c and 2-(methyldiphenylsilyl)ethyl (4-nitrophenyl)carbamate 1d were subsequently synthesized and their rate constants of disassembly determined. Although similar to the triphenylsilyl and 2-phenyl-2-trimethylsilyl ethoxycarbonyl protecting groups reported in the literature,11,12 we chose the methyldiphenylsilyl group because it was a hybrid of the aforementioned groups, the kinetics of phenyl-containing silyl groups had not been reported, and the lone methyl group provided a basis for larger aliphatic groups, which are discussed in subsequent paragraphs.Open in a separate windowScheme 1Products and proposed mechanism of disassembly for reaction of silyl-terminated carbonates and carbamates with TBAF.Rate constants of disassembly and percentage of silyl-terminated carbonates and carbamates remaining once treated with TBAF under non-stirred conditions
Open in a separate windowThe rate constants of 1c and 1d were found to be 355 ± 28 M−1 min−1 and 77.1 ± 0.2 M−1 min−1 (12 However, the rate constant of 1c was slower than 1a, which contradicted this rationale. To address the issue, we synthesized 1a and compared it to the rate constant of disassembly for the commercially available version, yet we found no change in the results. After viewing the first few seconds of the absorbance spectra we noticed the absorbance of 1a was decreasing slightly, even before addition of TBAF, which signified molecule instability at room temperature. This resulted in a faster rate constant compared to 1b when calculated via Excel plot. We currently do not have the ability to study the kinetics at reduced temperatures, but the instability supports literature examples for the use of 1a at 0 °C to protect organic functionality. On the contrary, 1c was stable at room temperature for weeks, and thus may be useful as an alternative protecting group for orthogonal chemistry.Once changes in the UV-visible spectra no longer appeared to occur, thus signifying that disassembly had slowed or ceased, the lowest absorbance of the silyl-terminated carbonates and carbamates was used to calculate the concentration of non-disassembled starting material. This, in-turn, could be represented as an approximate percentage of remaining starting material as shown in Scheme 2), and if so, how their rates differed from the non-extended molecules (1a–1d). We also aimed to confirm whether or not these extended molecules would provide an increased rate constant of disassembly when phenyl groups were attached to the silicon atom. To accomplish this, we developed a synthetic route to insert ethanolamine or N-methyl ethanolamine between the ethoxycarbonyl and aromatic chromophore (Scheme S1 of ESI†). Upon addition of 4 molar equivalents of 1.0 M TBAF in THF, silyl-terminated molecules 3a and 3b resulted in complete disassembly with rate constants of 42 638 ± 1720 M−1 min−1 and 46 049 ± 1860 M−1 min−1, respectively, whereas molecules 3c and 3d resulted in complete disassembly with rate constants of 118 711 ± 14 000 M−1 min−1 and 123 825 ± 4000 M−1 min−1, respectively (Scheme 2 and demonstrating that the rates were significantly enhanced by the entropic increase.18,19 Detection of the oxizolidinones were confirmed by GC-MS analysis of the reaction solutions after disassembly. The rate constants for the molecules containing N-methyl linkages (3b and 3d) were found to be greater than those with non-N-alkylated linkages (3a and 3c), which is consistent with the greater nucleophilicity of the resulting secondary amide ion (i.e., after loss of CO2) compared to those of primary amine ions. Furthermore, molecules with methyldiphenylsilyl groups (3c and 3d) proved to have faster rates of disassembly than those with trimethylsilyl groups (3a and 3b), which, as previously mentioned, is consistent with literature reports for enhanced reactivity at the silicon atom upon phenyl group attachment.Open in a separate windowScheme 2Products and proposed mechanisms of disassembly for reaction of silyl-terminated extended chain carbonates and carbamates with TBAF.Rate constants of disassembly and percentage of silyl-terminated extended chain carbonates and carbamates remaining once treated with TBAF under non-stirred conditions
Open in a separate windowaRates based on disappearance of starting material within first minutes.As shown in Scheme 2 the percentage of 4-nitrophenolate (2a) produced during disassembly was likely equivalent to the percentage of starting material disassembled.Following the results of the extended carbonates we decided to synthesize and determined the rate constants of disassembly for several silyl-terminated extended chain carbamates (3e–3h, Schemes 2 and S1 of ESI†). However, when each of these carbamates (λmax at 321 nm) were treated with 4 molar equivalents of 1.0 M TBAF in THF we observed the minor formation of a species with a similar absorption to 4-nitrophenylamide (2b, λmax of 445 nm), but we did not observe a peak for 4-nitroaniline (2c, λmax of 366 nm) or the appearance of any other peaks. Furthermore, the absorbance peak for the starting materials never decreased beyond 70%, even after monitoring the reaction for 24 hours, and treatment with 100 equivalents of TBAF did not influence the decrease in the starting materials. Although extend chain carbamates 3e–3h did not fully disassemble, we report the rates for loss of the starting materials during the first minutes of exposure to TBAF (†). This suggested that complete disassembly was possible, although the elevated temperature at the inlet likely facilitated disassembly. Furthermore, while the addition of TBAF at room temperature showed a new spot via TLC, we were unable to purify and analyse the by-product. Thus, we assume that fluoride ion attack at room temperature resulted in cleavage of the silyl group and elimination of ethylene and carbon dioxide, but that formation of the oxazolidinone ring did not occur due to the greater thermal barrier to cyclization at the carbamate linkage (i.e., compared to similar carbonates). As a result, protonation of the amide anion may have occurred, possibly by reaction with tetrabutylammonium ion via a Hofmann elimination. Protonation of the amide anion would also explain why the starting material never fully decreased, as the by-product would have a similar absorbance as the starting material.Akin to the extended chain carbonates, the absorbance of extended chain carbamates 3e–3h after 10 minutes could be used to calculate an approximate percentage of non-disassembled starting material. However, unlike the carbonates, the carbamates did not completely disassemble, thus the percentage of generated arene chromophores could not be determined.Our focus then turned to the synthesis of novel silyl-centered molecules, such as bis(ethoxycarbamates) (5a and 5b) and bis(ethoxycarbonates) (5c and 5d) (Scheme S2 of ESI†). Upon treatment of (dimethylsilanediyl)bis(ethane-2,1-diyl) bis((4-nitrophenyl)carbamate) (5a, Scheme 3) with 8 molar equivalents of 1.0 M TBAF in THF we detected 4-nitrophenolate (2b), followed by the formation of 2c, and calculated a rate constant of disassembly of 967 ± 14 M−1 min−1 (Scheme 3. Silyl-centered molecule (diphenylsilanediyl)bis(ethane-2,1-diyl) bis((4-nitrophenyl)carbamate) (5b), when treated with 8 molar equivalents of TBAF in THF, demonstrated a rate constant of 1733 ± 30 M−1 min−1, which followed a similar trend for silyl-terminated molecules where the electrophilicity of silicon was increased upon phenyl group attachment. It is important to note that 8 molar equivalents of TBAF were used in order to maintain a ratio of 4 molar equivalents per UV-detectable end group. However, when 4 molar equivalents of TBAF were utilized the rates for 5a and 5b were 50% slower, thus confirming the second order reaction. Nevertheless, these rates were still faster when compared to silyl-terminated molecules 1b and 1d.Open in a separate windowScheme 3Products and proposed mechanism of disassembly for reaction of silyl-centered bis(ethoxycarbonyls) with TBAF.Rate constants of disassembly and percentage of silyl-centered bis(ethoxycarbonates) and bis(ethoxycarbamates) remaining once treated with TBAF under non-stirred conditions
Open in a separate windowIn contrast to the bis(ethoxycarbamates), silyl-centered bis(ethoxycarbonates) (5c and 5d) demonstrated a significant increase in their rates of disassembly compared to silyl-terminated carbonates. For instance, the rate constant for 5c was 38 358 ± 2200 M−1 min−1, about a 39-fold increase compared to 5a. However, the rate for 5d was 404 699 ± 64 100 M−1 min−1, about a 233-fold increase compared to 5b and about a 10-fold increase compared to 5c (相似文献
Entry | Structure | k (M−1 min−1) | Approx. % remaining |
---|---|---|---|
1a | 2196 ± 1380 | 0 | |
1b | 38.5 ± 0.3 | 68 | |
1c | 355 ± 28 | 41 | |
1d | 77.1 ± 0.2 | 27 |
Entry | Structure | k (M−1 min−1) | Approx. % remaining |
---|---|---|---|
3a | 42 638 ± 1720 | 16 | |
3b | 46 049 ± 1860 | 15 | |
3c | 118 711 ± 14 000 | 16 | |
3d | 123 825 ± 4000 | 13 | |
3e | 70.7 ± 38.4a | 53 | |
3f | 122 608 ± 15 654a | 34 | |
3g | 1134 ± 787a | 38 | |
3h | 244 851 ± 39 000a | 26 |
Entry | Structure | k (M−1 min−1) | Approx. % remaining |
---|---|---|---|
5a | 967 ± 14 | 35 | |
5b | 1733 ± 30 | 34 | |
5c | 38 358 ± 2200 | 31 | |
5d | 404 699 ± 64 100 | 16 |
6.
7.
A Human Clinical,Histological, Histomorphometrical,and Radiographical Study on Biphasic HA‐Beta‐TCP 30/70 in Maxillary Sinus Augmentation
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8.
Danilo Alessio Di Stefano Paolo Arosio Adriano Piattelli Vittoria Perrotti Giovanna Iezzi 《The journal of advanced prosthodontics》2015,7(1):51-55
PURPOSE
Bone density at implant placement site is a key factor to obtain the primary stability of the fixture, which, in turn, is a prognostic factor for osseointegration and long-term success of an implant supported rehabilitation. Recently, an implant motor with a bone density measurement probe has been introduced. The aim of the present study was to test the objectiveness of the bone densities registered by the implant motor regardless of the operator performing them.MATERIALS AND METHODS
A total of 3704 bone density measurements, performed by means of the implant motor, were registered by 39 operators at different implant sites during routine activity. Bone density measurements were grouped according to their distribution across the jaws. Specifically, four different areas were distinguished: a pre-antral (between teeth from first right maxillary premolar to first left maxillary premolar) and a sub-antral (more distally) zone in the maxilla, and an interforaminal (between and including teeth from first left mandibular premolar to first right mandibular premolar) and a retroforaminal (more distally) zone in the lower one. A statistical comparison was performed to check the inter-operators variability of the collected data.RESULTS
The device produced consistent and operator-independent bone density values at each tooth position, showing a reliable bone-density measurement.CONCLUSION
The implant motor demonstrated to be a helpful tool to properly plan implant placement and loading irrespective of the operator using it. 相似文献9.
Jamil A. Shibli Carlo Mangano Francesco Mangano José A. Rodrigues Alessandra Cassoni Karen Bechara Jose Divino B. Ferreia Alexandre M. Dottore Giovanna Iezzi Adriano Piattelli 《Journal of periodontology》2013,84(6):732-737
Objective: Direct laser metal forming (DLMF) is a procedure in which a high‐power laser beam is directed onto a metal powder bed and programmed to fuse particles according to a computer‐aided design file, generating a thin metal layer. This histologic study evaluated the bone‐to‐implant contact (BIC%) around immediately loaded DLMF transitional implants retrieved after 2 months from posterior human maxillae. Methods: Twelve totally edentulous individuals (mean age, 66.14 ± 2.11 years) received DLMF transitional implants divided in twelve immediately loaded (IL) and twelve unloaded (UI) implants. These transitional implants were placed between conventional implants to support the interim complete maxillary denture during the healing period. After 8 weeks, the transitional implants and the surrounding tissue were removed and prepared for histomorphometric analysis. Results: Mature woven preexisting bone lined by newly formed bone in early stages of maturation were found around all retrieved implants. Histometric evaluation indicated that the mean BIC% was 45.20 ± 7.68% and 34.10 ± 7.85% for IL and UI, respectively (P <0.05). Conclusion: The present data obtained in humans showed that, although both IL and UI presented good BIC%, IL DLMF implants had a higher BIC% in the posterior maxilla. 相似文献
10.
Giuseppe Corinaldesi Luigi Piersanti Adriano Piattelli Giovanna Iezzi Francesco Pieri Claudio Marchetti 《The British journal of oral & maxillofacial surgery》2013
The aim of this study was to evaluate the quantity and quality of bony regeneration after we had used recombinant human bone morphogenetic protein-7 (rhBMP-7 to augment the floor of the maxillary sinus. Nine consecutive patients with bilateral posterior maxillary atrophy who required augmentation of the sinus for interposition of implants were treated simultaneously with rhBMP-7 (Osigraft) with deproteinised bone substitute (0.5 g on the test side) and with deproteinised bone alone (2.0 g on the control side). Computed tomographic images preoperatively, immediately postoperatively, and at 4 months postoperatively showed a mean (SD) postoperative gain of 10.8 (3.0) mm on the test side and of 10.2 (1.8) mm on the control side. Histological and histomorphometric analyses of biopsy specimens showed that there was significantly more new bone on the control side (19.9 (6.8)%) than on the test side (6.6 (4.8)%). In this pilot controlled trial of the use of rhBMP-7, histological analyses showed that it resulted in the formation of less bone than treatment with inorganic bovine hydroxyapatite. 相似文献