Dietary intake and glutamine-serine metabolism control pathologic vascular stiffness.

Perivascular collagen deposition by activated fibroblasts promotes vascular stiffening and drives cardiovascular diseases such as pulmonary hypertension (PH). Whether and how vascular fibroblasts rewire their metabolism to sustain collagen biosynthesis remains unknown. Here, we found that inflammation, hypoxia, and mechanical stress converge on activating the transcriptional coactivators YAP and TAZ (WWTR1) in pulmonary arterial adventitial fibroblasts (PAAFs). Consequently, YAP and TAZ drive glutamine and serine catabolism to sustain proline and glycine anabolism and promote collagen biosynthesis. Pharmacologic or dietary intervention on proline and glycine anabolic demand decreases vascular stiffening and improves cardiovascular function in PH rodent models. By identifying the limiting metabolic pathways for vascular collagen biosynthesis, our findings provide guidance for incorporating metabolic and dietary interventions for treating cardiopulmonary vascular disease.

Classification of Breast Implant Malposition.

BACKGROUND: Implant malposition is a well-recognized complication when using prosthetic implants in the breast for both reconstructive and aesthetic indications. However, to date, no objective classification system has been described. OBJECTIVES: This study presents a prospective trial of an objective and reproducible classification system for implant malposition formulated using retrospective data from a large cohort of patients with implant malposition. METHODS: The authors retrospectively analyzed the degree of medial/lateral and inferior/superior implant malposition relative to their optimal position within the breast footprint in a series of 189 breasts (n = 100 patients). An objective classification system for implant malposition was devised and then applied to a prospective cohort of 53 breasts in 28 patients with implant malposition. RESULTS: The degree of malposition in a single or combination of axes was categorised according to the distance from the ideal breast footprint and measured in centimeters (cms). The classification system incorporated the axis of malposition and distance to generate a treatment decision-making guide. Cases of Grade 1 malposition did not warrant surgical intervention, whilst surgical correction was warranted in all Grade 3 cases.In the combined patient cohort (n = 242 breasts, 128 patients), lateral, inferior, medial and superior displacement ranged between grades 1-3. There was no inter-observer variability in the grades assigned to nine out of ten patients in the prospective group. CONCLUSIONS: We have created a simple and reproducible classification system for implant malposition that allows surgeons to objectively record the extent of malposition, guides surgical decision-making and can be used to document the results of any intervention.

Modifier 22 Use in Fee-for-Service Medicare.

Importance: Modifier 22 is a mechanism designed for surgeons to identify cases that are more complex than their Current Procedural Terminology code accounts for. However, empirical studies of the use and efficacy of modifier 22 are lacking. Objective: To assess the use of modifier 22 in common surgical procedures and the association of use with compensation. Design, Setting, and Participants: This was a cross-sectional analysis of the 2021 Physician/Supplier Procedure Summary Limited Data Set including all Part B carrier and durable medical equipment fee-for-service claims. Claims for 10 common surgical procedures were evaluated, including mastectomy, total hip arthroplasty, total knee arthroplasty, coronary artery bypass grafting, laparoscopic right colectomy, laparoscopic appendectomy, laparoscopic cholecystectomy, kidney transplant, laparoscopic total abdominal hysterectomy and bilateral salpingo-oophorectomy, and lumbar laminectomy. Data were analyzed from August to November 2023. Main Outcomes and Measures: Rate of modifier 22 use, rate of claim denial, mean charges, mean payment for accepted claims, and mean payment for all claims. Results: The sample included 625 316 surgical procedures performed in calendar year 2021. The proportion of modifier 22 coding for a procedure ranged from 5725 of 251 521 (2.3%) in total knee arthroplasty to 1566 of 18 459 (8.5%) in laparoscopic total abdominal hysterectomy and bilateral salpingo-oophorectomy. Submitted charges were 11.1% (95% CI, 9.1-13.2) to 22.8% (95% CI, 21.3-24.3) higher for claims with modifier 22, depending on the procedure. Among accepted claims, those with modifier 22 had increased payments ranging from 0.8% (95% CI, 0.7-1.0) to 4.8% (95% CI, 4.5-5.1). However, claims with modifier 22 were more likely to be denied (7.4% vs 4.0%; P < .001). As a result, overall mean payments were mixed, with 4 procedures having lower payments when modifier 22 was appended, 4 procedures having higher payments with modifier 22, and 2 procedures with no difference. The largest increase in mean payment for modifier 22 claims was for kidney transplant with an increased payment of $71.46 (95% CI, 55.32-87.60), which translates to a relative increase of 3.4% (95% CI, 2.9-4.6). Conclusions and Relevance: The findings in this study suggest that modifier 22 had little to no financial benefit when appended to claims for a diverse panel of surgical procedures. In the current system, surgeons have little reason to request modifier 22, and no mechanisms currently exist for surgeons to recoup payment for difficult operations.

GelMA Hydrogel Reinforced with 3D Printed PEGT/PBT Scaffolds for Supporting Epigenetically-Activated Human Bone Marrow Stromal Cells for Bone Repair.

Epigenetic approaches using the histone deacetylase 2 and 3 inhibitor-MI192 have been reported to accelerate stem cells to form mineralised tissues. Gelatine methacryloyl (GelMA) hydrogels provide a favourable microenvironment to facilitate cell delivery and support tissue formation. However, their application for bone repair is limited due to their low mechanical strength. This study aimed to investigate a GelMA hydrogel reinforced with a 3D printed scaffold to support MI192-induced human bone marrow stromal cells (hBMSCs) for bone formation. Cell culture: The GelMA (5 wt%) hydrogel supported the proliferation of MI192-pre-treated hBMSCs. MI192-pre-treated hBMSCs within the GelMA in osteogenic culture significantly increased alkaline phosphatase activity (p ≤ 0.001) compared to control. Histology: The MI192-pre-treated group enhanced osteoblast-related extracellular matrix deposition and mineralisation (p ≤ 0.001) compared to control. Mechanical testing: GelMA hydrogels reinforced with 3D printed poly(ethylene glycol)-terephthalate/poly(butylene terephthalate) (PEGT/PBT) scaffolds exhibited a 1000-fold increase in the compressive modulus compared to the GelMA alone. MI192-pre-treated hBMSCs within the GelMA-PEGT/PBT constructs significantly enhanced extracellular matrix collagen production and mineralisation compared to control (p ≤ 0.001). These findings demonstrate that the GelMA-PEGT/PBT construct provides enhanced mechanical strength and facilitates the delivery of epigenetically-activated MSCs for bone augmentation strategies.

Nanoencapsulation of casein-derived peptides within electrospun nanofibres.

BACKGROUND: Bioactive peptides derived from milk proteins are recognized as functional foods, but their consumption is limited by undesirable or bitter flavour, poor stability, and low bioavailability. Electrospinning is a versatile process for encapsulation of various bioactive compounds in the form of nanosized fibres, which can circumvent these disadvantages. This study was aimed at the preparation of casein-derived peptides-loaded nanofibres through electrospinning and characterizing them for fortification of milk. RESULTS: Pullulan at 100, 120, and 140 g kg-1 concentrations was used for electrospinning of peptides. Scanning electron and atomic force micrographs revealed the formation of clean bead-free peptides-loaded pullulan nanofibres at 120 and 140 g kg-1 concentrations with mean diameter of 60.45-133.05 nm and encapsulation efficiency of 72.95-86.04%. Fourier transform infrared spectra and X-ray diffractograms revealed the absence of interactions between the functional groups of pullulan and peptides during electrospinning. The zeta potential of the peptides-loaded nanofibres ranged from -15.6 to -24.6 mV, and the hydrodynamic diameter varied from 118.7 to 256.2 nm. The peptides from electrospun nanofibres showed sustained release to the extent of 75.3% after 8 h in gastrointestinal pH conditions. The release kinetics of peptides from nanofibres was best fitted to a Peppas-Sahlin model (R2  = 0.987), and through diffusion and erosion mechanisms. The antioxidant activity of pure peptides and those from nanofibres was comparable. The physico-chemical qualities of milk fortified with encapsulated peptides did not show noticeable difference either. CONCLUSIONS: From the morphological, ultrastructural, particle size, encapsulation efficiency, release kinetics, and antioxidant activity data, it was inferred that electrospinning could be an effective technique for nanoencapsulation of casein-derived bioactive peptides. These peptides-loaded nanofibres could be used for fortification of milk and milk products. © 2021 Society of Chemical Industry.

Dehydrogenation of 1-Phenylethanol Catalyzed by Nickel(II)diphosphine Complexes.

Catalytic efficacy of the nickel(II)-diphosphine systems in the dehydrogenation of 1-phenylethanol to acetophenone under acceptorless conditions was investigated. Steric and electronic factors of the phosphine ligands were found to play an important role in the catalysis, while the nature of the base used and the reaction conditions, viz. time, temperature, and stoichiometry, have also shown major influence. Based on the preliminary analysis, a homogeneous pathway, perhaps involving nickel hydride species, was proposed. Due to the gradual disintegration of the catalytic species, deterioration of catalytic activity was observed resulting into low to moderate conversions. Among the series of catalysts examined, the highest conversion of 52% was exhibited by the catalyst C4, dichloro(1,2-bis(diphenylphosphino)ethane)nickel(II) (5 mol%), when loaded with 50 mol% of sodium ethoxide in toluene at 120 °C.

MI192 induced epigenetic reprogramming enhances the therapeutic efficacy of human bone marrows stromal cells for bone regeneration.

Human bone marrow stromal cells (hBMSCs) have been extensively utilised for bone tissue engineering applications. However, they are associated with limitations that hinder their clinical utility for bone regeneration. Cell fate can be modulated via altering their epigenetic functionality. Inhibiting histone deacetylase (HDAC) enzymes have been reported to promote osteogenic differentiation, with HDAC3 activity shown to be causatively associated with osteogenesis. Therefore, this study aimed to investigate the potential of using an HDAC2 & 3 selective inhibitor - MI192 to induce epigenetic reprogramming of hBMSCs and enhance its therapeutic efficacy for bone formation. Treatment with MI192 caused a time-dose dependant reduction in hBMSCs viability. MI192 was also found to substantially alter hBMSCs epigenetic function through reduced HDAC activity and increased histone acetylation. hBMSCs were pre-treated with MI192 (50 µM) for 48 h prior to osteogenic induction. MI192 pre-treatment significantly upregulated osteoblast-related gene/protein expression (Runx2, ALP, Col1a and OCN) and enhanced alkaline phosphatase specific activity (ALPSA) (1.43-fold) (P ≤ 0.001). Moreover, MI192 substantially increased hBMSCs extracellular matrix calcium deposition (1.4-fold) (P ≤ 0.001) and mineralisation when compared to the untreated control. In 3D microtissue culture, MI192 significantly promoted hBMSCs osteoblast-related gene expression and ALPSA (> 2.41-fold) (P ≤ 0.001). Importantly, MI192 substantially enhanced extracellular matrix deposition (ALP, Col1a, OCN) and mineralisation (1.67-fold) (P ≤ 0.001) within the bioassembled-microtissue (BMT) construct. Following 8-week intraperitoneal implantation within nude mice, MI192 treated hBMSCs exhibited enhanced extracellular matrix deposition and mineralisation (2.39-fold) (P ≤ 0.001) within the BMT when compared to the untreated BMT construct. Taken together, these results demonstrate that MI192 effectively altered hBMSCs epigenetic functionality and is capable of promoting hBMSCs osteogenic differentiation in vitro and in vivo, indicating the potential of using epigenetic reprogramming to enhance the therapeutic efficacy of hBMSCs for bone augmentation strategies.

In Vitro Antiviral Activity of α-Mangostin against Dengue Virus Serotype-2 (DENV-2).

Dengue virus (DENV), a member of the family Flaviviridae, is a threat for global health as it infects more than 100 million people yearly. Approved antiviral therapies or vaccines for the treatment or prevention of DENV infections are not available. In the present study, natural compounds were screened for their antiviral activity against DENV by in vitro cell line-based assay. α-Mangostin, a xanthanoid, was observed to exert antiviral activity against DENV-2 under pre-, co- and post-treatment testing conditions. The antiviral activity was determined by foci forming unit (FFU) assay, quantitative RT-PCR and cell-based immunofluorescence assay (IFA). A complete inhibition of DENV-2 was observed at 8 µM under the co-treatment condition. The possible inhibitory mechanism of α-Mangostin was also determined by docking studies. The molecular docking experiments indicate that α-Mangostin can interact with multiple DENV protein targets such as the NS5 methyltransferase, NS2B-NS3 protease and the glycoprotein E. The in vitro and in silico findings suggest that α-Mangostin possesses the ability to suppress DENV-2 production at different stages of its replication cycle and might act as a prophylactic/therapeutic agent against DENV-2.

In vitro and in vivo studies reveal α-Mangostin, a xanthonoid from Garcinia mangostana, as a promising natural antiviral compound against chikungunya virus.

BACKGROUND: Chikungunya virus (CHIKV), a serious health problem in several tropical countries, is the causative agent of chikungunya fever. Approved antiviral therapies or vaccines for the treatment or prevention of CHIKV infections are not available. As diverse natural phenolic compounds have been shown to possess antiviral activities, we explored the antiviral activity of α-Mangostin, a xanthanoid, against CHIKV infection. METHODS: The in vitro prophylactic and therapeutic effects of α-Mangostin on CHIKV replication in Vero E6 cells were investigated by administering it under pre, post and cotreatment conditions. The antiviral activity was determined by foci forming unit assay, quantitative RT-PCR and cell-based immune-fluorescence assay. The molecular mechanism of inhibitory action was further proposed using in silico molecular docking studies. RESULTS: In vitro studies revealed that 8 µM α-Mangostin completely inhibited CHIKV infectivity under the cotreatment condition. CHIKV replication was also inhibited in virus-infected mice. This is the first in vivo study which clearly showed that α-Mangostin is effective in vivo by significantly reducing virus replication in serum and muscles. Molecular docking indicated that α-Mangostin can efficiently interact with the E2-E1 heterodimeric glycoprotein and the ADP-ribose binding cavity of the nsP3 macrodomain. CONCLUSIONS: The findings suggest that α-Mangostin can inhibit CHIKV infection and replication through possible interaction with multiple CHIKV target proteins and might act as a prophylactic/therapeutic agent against CHIKV.

Management of Acute Gastric Remnant Complications After Roux-en-Y Gastric Bypass: a Single-Center Case Series.

PURPOSE: Roux-en-Y gastric bypass is a common bariatric procedure. Its configuration creates an excluded gastric remnant, which is subject to potential acute complications such as bleeding, perforation, and necrosis. MATERIAL AND METHODS: A retrospective analysis of a prospective database including all patients presenting between 2007 and 2019 to our institution with acute gastric remnant complications after RYGB was performed. RESULTS: Seven patients were included, including 3 hemorrhages, two of which were treated with double-balloon enteroscopy, as well as 3 perforations and 1 necrosis, all of which required emergent surgery. Overall gastric remnant complication rate was 0.3% in this series. CONCLUSION: Acute gastric remnant complications after RYGB are infrequent, but their diagnosis and management can be challenging. Double-balloon enteroscopy has diagnostic and therapeutic value for selected patients. Emergent surgery remains the standard of care for unstable patients and should not be delayed.

Self-healing microcapsules encapsulated with carbon nanotubes for improved thermal and electrical properties.

Microcapsules are widely used by researchers in self-healing composites. In this study, multi-walled carbon nanotubes (CNT) were incorporated into the core of the microcapsules, along with the self-healing agent. Dicyclopentadiene (DCPD) and urea-formaldehyde (UF) were chosen as the core and shell materials respectively, and DCPD-CNT-UF based dual core microcapsules were synthesized. Two types of microcapsules, namely, DCPD-UF and DCPD-CNT-UF were successfully synthesized by the in situ polymerization technique. The novelty of this work is the development of dual core microcapsules with DCPD-CNT-UF combination. Surface morphology characterization and elemental analysis of the microcapsules were carried out using a scanning electron microscope (SEM-EDX). TGA and DSC analysis show that DCPD-CNT-UF microcapsules have better thermal stability than DCPD-UF microcapsules. These novel DCPD-CNT-UF microcapsules were found to be compatible with epoxy base resin for making resin castings. The presence of CNT is found to improve the mechanical, thermal and electrical properties of the resin cast specimens without compromising on self-healing efficiency.

Mutant p53R175H promotes cancer initiation in the pancreas by stabilizing HSP70.

Pancreatic cancer remains a highly lethal malignancy. We have recently shown that simultaneous expression of Kras and mutant Tp53R175H promotes invasive ductal adenocarcinoma from pancreatic ductal cells. We hypothesized specific mutations in TP53 have divergent mechanisms of transforming ductal cells. In order to understand the role of mutant TP53 in transforming pancreatic ductal cells, we used a lentiviral system to express mutant TP53R175H and TP53R273H, two of the most frequently mutated TP53 alleles in pancreatic cancer patients, in immortalized, but not transformed, pancreatic ductal epithelial cells carrying a KRAS mutation (HPNE:KRASG12D). Mutant TP53 expression enhanced colony formation and an RPPA assay results revealed TP53R175H uniquely induced HSP70 expression in HPNE:KRASG12D cells. In the context of TP53R175H expression; we observed nuclear localization of HSP70. We performed immunoprecipitation experiments to show mutant p53R175H binds to HSP70. We also provide evidence mutant p53R175H is important for HSP70 stability and, more importantly, HSP70 is required for mutant p53 stability. These data are critical in the context of events leading to cellular transformation in the pancreas.

Monoanionic, Bis(pyrazolyl)methylborate [(Ph3B)CH(3,5-(CH3)2Pz)2)]- as a Supporting Ligand for Copper(I)-ethylene, cis-2-Butene, and Carbonyl Complexes.

The monoanionic bidentate ligand [(Ph3B)CH(3,5-(CH3)2Pz)2)]- has been prepared from lithium bis(pyrazolyl)methanide and triphenylborane. This useful new ligand is closely related to the well-established bis(pyrazolyl)borate and bis(pyrazolyl)methane ligands but has key differences to both analogues as well. The ethylene, cis-2-butene, and carbon monoxide adducts [(Ph3B)CH(3,5-(CH3)2Pz)2]Cu(L) (where L = C2H4, cis-CH3HC═CHCH3, and CO) have been prepared from [(Ph3B)CH(3,5-(CH3)2Pz)2)]Li(THF), copper(I) triflate, and the corresponding coligand. These complexes have been characterized by NMR spectroscopy and X-ray crystallography. In all cases the bis(pyrazolyl) moiety is bound in κ2N fashion with the BPh3 group rotated to sit over the metal center, sometimes coordinating to the metal via phenyl carbons as in [(Ph3B)CH(3,5-(CH3)2Pz)2)]Li(THF) and [(Ph3B)CH(3,5-(CH3)2Pz)2]Cu(CO) or simply hovering above the metal site as in [(Ph3B)CH(3,5-(CH3)2Pz)2)]Cu(C2H4) and [(Ph3B)CH(3,5-(CH3)2Pz)2)]Cu(cis-CH3HC═CHCH3). The 13C and 1H resonances of the ethylene carbon and protons of [(Ph3B)CH(3,5-(CH3)2Pz)2)]Cu(C2H4) appear at δ 81.0 and 3.71 ppm in CD2Cl2, respectively. The characteristic CO frequency for [(Ph3B)CH(3,5-(CH3)2Pz)2]Cu(CO) has been observed at υ̅ 2092 cm-1 by infrared spectroscopy and is lower than that of free CO suggesting moderate M → CO π-back-donation. A detailed analysis of these complexes has been presented herein.

Fluorinated triazapentadienyl ligand supported ethyl zinc(ii) complexes: reaction with dioxygen and catalytic applications in the Tishchenko reaction.

Ethyl zinc complexes [N{(C3F7)C(Dipp)N}2]ZnEt, [N{(C3F7)C(Cy)N}2]ZnEt, [N{(CF3)C(2,4,6-Br3C6H2)N}2]ZnEt and [N{(C3F7)C(2,6-Cl2C6H3)N}2]ZnEt have been synthesized from the corresponding 1,3,5-triazapentadiene and diethyl zinc. X-ray data show that [N{(C3F7)C(Dipp)N}2]ZnEt has a distorted trigonal planar geometry at the zinc center. The triazapentadienyl ligand binds to zinc in a κ(2)-mode. The zinc-ethyl bonds of [N{(C3F7)C(Dipp)N}2]ZnEt, [N{(C3F7)C(Cy)N}2]ZnEt, [N{(CF3)C(2,4,6-Br3C6H2)N}2]ZnEt and [N{(C3F7)C(2,6-Cl2C6H3)N}2]ZnEt readily undergo oxygen insertion upon exposure to dry air to produce the corresponding zinc-ethoxy or zinc-ethylperoxy compounds. The ethoxy zinc adducts {[N{(CF3)C(2,4,6-Br3C6H2)N}2]ZnOEt}2 and {[N{(C3F7)C(2,6-Cl2C6H3)N}2]ZnOEt}2 as well as the ethylperoxy zinc adduct {[N{(C3F7)C(Cy)N}2]ZnOOEt}2 have been isolated and fully characterized by several methods including X-ray crystallography. They feature dinuclear structures with four-coordinate zinc sites and bridging-ethoxy or -ethylperoxy groups. The ethyl zinc complexes catalyze the Tishchenko reaction of benzaldehyde under solventless conditions affording benzyl benzoate. The reaction of ethyl zinc complexes with dioxygen and their catalytic behaviour in the Tishchenko reaction are affected by the electronic and steric factors of the triazapentadienyl ligand. {[N{(C3F7)C(Cy)N}2]ZnOOEt}2 is an excellent reagent for the epoxidation of trans-chalcone.

New Visible-Light Photoinitiating System for Improved Print Fidelity in Gelatin-Based Bioinks.

Oxygen inhibition is a phenomenon that directly impacts the print fidelity of 3D biofabricated and photopolymerized hydrogel constructs. It typically results in the undesirable physical collapse of fabricated constructs due to impaired cross-linking, and is an issue that generally remains unreported in the literature. In this study, we describe a systematic approach to minimizing oxygen inhibition in photopolymerized gelatin-methacryloyl (Gel-MA)-based hydrogel constructs, by comparing a new visible-light initiating system, Vis + ruthenium (Ru)/sodium persulfate (SPS) to more conventionally adopted ultraviolet (UV) + Irgacure 2959 system. For both systems, increasing photoinitiator concentration and light irradiation intensity successfully reduced oxygen inhibition. However, the UV + I2959 system was detrimental to cells at both high I2959 concentrations and UV light irradiation intensities. The Vis + Ru/SPS system yielded better cell cyto-compatibility, where encapsulated cells remained >85% viable even at high Ru/SPS concentrations and visible-light irradiation intensities for up to 21 days, further highlighting the potential of this system to biofabricate cell-laden constructs with high shape fidelity, cell viability, and metabolic activity.

Zinc(II)-Mediated Carbene Insertion into C-H Bonds in Alkanes.

The cationic zinc adduct {[HB(3,5-(CF3)2Pz)3]Zn(NCMe)2}ClO4 catalyzes the functionalization of tertiary, secondary, and primary C-H bonds of alkanes via carbene insertion. Ethyl diazoacetate serves as the :CHCO2Et carbene precursor. The counteranion, supporting ligand, and coordinating solvents affect the catalytic activity. An in situ generated {[HB(3,5-(CF3)2Pz)3]Zn}(+) species containing a bulkier {B[3,5-(CF3)2C6H3]4}(-) anion gives the best results among the zinc catalysts used.

Zinc-Mediated Carbene Insertion to C-Cl Bonds of Chloromethanes and Isolable Zinc(II) Isocyanide Adducts.

The zinc adduct {[HB(3,5-(CF3)2Pz)3]Zn}(+), which was generated from [HB(3,5-(CF3)2Pz)3]ZnEt and [Ph3C]{B[3,5-(CF3)2C6H3]4}, catalyzes the activation of C-halogen bonds of chloromethanes via carbene insertion. Ethyl diazoacetate serves as the carbene precursor. The presence of {[HB(3,5-(CF3)2Pz)3]Zn}(+) in the reaction mixture was confirmed by obtaining {[HB(3,5-(CF3)2Pz)3]Zn(CN(t)Bu)3}(+) using CN(t)Bu as a trapping agent. {[HB(3,5-(CF3)2Pz)3]Zn(CN(t)Bu)3}(+) loses one zinc-bound CN(t)Bu easily to produce five-coordinate {[HB(3,5-(CF3)2Pz)3]Zn(CN(t)Bu)2}(+).

Treatment of ectopic mandibular second permanent molar with elastic separators.

Ectopic eruption is a developmental disturbance in which the tooth fails to follow its normal eruption pathway. Ectopic eruption of the second molar is relatively rare. This paper presents the case of thirteen-year-old male with an ectopic mandibular second permanent molar. The condition was corrected with surgical exposure and placement of elastic separators. This case report lays emphasis on the practice of basic methods to obtain acceptable results rather than extensive surgical or orthodontic corrections. It is advised that ectopic teeth should not be neglected especially when it concerns developing caries and malocclusion.

Polymerization of propylene promoted by zirconium benzamidinates.

New bis(N,N-trimethylsilylarylamidinate) zirconium dichloride complexes with various carbon substituents were prepared, and their solid as well as solution state structures were studied. In the polymerization of propylene, after activation by MAO, these catalysts provided two fractions. Ether soluble polymers were obtained at a low activity as sticky polymers with lower molecular weights, except with the o-OMe substituted complex. The solid fractions were composed of a highly isotactic polymer and a moderately syndiotactic polymer. An interesting linear correlation was found between the rates of the 2,1 and 3,1 insertions for the ether soluble fractions.