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Swept-source optical coherence tomography (SSOCT) is a noncontact, noninvasive bioimaging tool that uses various probes to obtain high contrast images. Rare-earth based upconversion particles (UCPs...

Introduction:The aim of this study was to evaluate repeatability and reproducibility of newly calculated biomechanical parameters of the cornea, developed by our research group.Methods:One eye from each of the 23 healthy subjects was measured three times consecutively, three times at different daytimes and on three different days. The within-subject standard deviation and coefficient of variation, as well as the intraclass correlation coefficient, were calculated for every parameter in each group.Results:Excellent repeatability and reproducibility (coefficient of variation < 5%, intraclass correlation coefficient > 0.75) was found for corrected values measured at A1, HC, and A2 time points (2nd A2 Time, 2nd A1 Time, 2nd HC Time, 2nd HC Def Amp and 2nd A1 Def Amp). Corneal-specific stiffness parameters, which showed good repeatability and reliability, were DA_cor (coefficient of variation = 4.02%, intraclass correlation coefficient = 0.919), KcLinear (coefficient of variation = 4.03%, intraclass correlation coefficient = 0.895), areaForceCornea (coefficient of variation = 3.34%, intraclass correlation coefficient = 0.853) and E2 (coefficient of variation = 4.1%, intraclass correlation coefficient = 0.78). Overall, most parameters fell into the category of good reliability (high intraclass correlation coefficient) and poor reproducibility (low coefficient of variation), including all the parameters describing extraocular deformation (DA_ext, AEPvED, AUC EDef, areaForceExtra, Kg and μg). Comparing the coefficient of variation values for intrasession, intersession and daytime measurements, there were no indices for diurnal changes.Conclusion:Most parameters showed good repeatability and reliability. The extraocular stiffness parameters showed poor reproducibility. KcLinear can serve as a very reliable and repeatable indicator of corneal stiffness.

Develop a clinically relevant and reproducible endoscopic animal model for subglottic stenosis amenable to testing of minimally invasive therapeutic modalities.Cohort study.Division of Laboratory Animals Research, University of Pittsburgh.Subglottic stenosis was induced endoscopically via microsuspension laryngoscopy in 26 New Zealand white rabbits. A trimmed polypropylene brush connected to a novel electronic stenosis induction apparatus was used to create circumferential trauma to the subglottis. By using open source image analysis software, the cross-sectional areas of the stenotic and native airways were compared to calculate the percentage of stenosis and the Myer-Cotton classification grade.Of the 26 rabbits, 24 (92%) exhibited stenosis after the first attempt. The mean percentage of airway stenosis was 57% (range, 34%-85%; SD, 15%). Five rabbits (19.2%) died on the day of stenosis induction from procedural complications. Of the 21 rabbits, 2 demonstrated no stenosis 7 days after initial injury and so underwent reinduction of airway injury, upon which they developed stenosis. Overall, 14 of the 21 rabbits (67%) exhibited moderate to severe stenosis (grade 2 or 3).The stenosis induction apparatus reliably induced stenosis with a low mortality rate as compared with that of other methods in the literature. The device could be improved to generate a predetermined potentially reproducible grade of stenosis as desired by the operator. This method sets the stage for a clinically relevant and reproducible subglottic stenosis disease model that is amenable to testing of minimally invasive treatment modalities.

Early detection of malignancy is important in order to reduce morbidity and mortality rate. However, existing approaches are based on a single modality having limited performance. Hence, the key objective of this study is detection and validation of breast cancer images using multimodality approach by combining both ultrasonography and mammography. Further, we investigate a particular segmentation approach that can accurately detect breast lesions using a dual-modality system. Three popular techniques i.e. Fuzzy-c-Means (FCM), and K-means (KM) and DPSO (Darwinian Particle swarm optimization) are experimented and evaluated for detecting lesions using combined ultrasonography and mammography. Performance measures such as the area of breast mass lesions, Jaccard Index (JI) and Dice Similarity Coefficient (DSC) have been used for the evaluation of the proposed dual modality breast cancer detection model. The results show that out of the implemented techniques, FCM outperformed others in detecting the lesion on both ultrasonography and mammography images with JI: highest average value (0.748) and lowest SD (0.124), DSC: highest average value (0.851) and lowest SD (0.084) and segmentation accuracy: highest average value (0.92) and lowest SD (0.074).

Pediatric laryngotracheal stenosis is a complex congenital or acquired airway injury that may manifest into a potentially life-threatening airway emergency condition. Depending on the severity of obstruction, treatment often requires a combination of endoscopic techniques, open surgical repair, intraluminal stenting, or tracheostomy. A balloon expandable biodegradable airway stent maintaining patency while safely degrading over time may address the complications and morbidity issues of existing treatments providing a less invasive and more effective management technique. Previous studies have focused on implementation of degradable polymeric scaffolds associated with potentially life-threatening pitfalls. The feasibility of an ultra-high ductility magnesium-alloy based biodegradable airway stents was demonstrated for the first time. The stents were highly corrosion resistant under in vitro flow environments, while safely degrading in vivo without affecting growth of the rabbit airway. The metallic matrix and degradation products were well tolerated by the airway tissue without exhibiting any noticeable local or systemic toxicity., Wu et al. demonstrate utility of a novel, ultrahigh ductility Mg alloy-based biodegradable stent in vitro and in vivo for use in congenital disorders like pediatric laryngotracheal stenosis. Tested in both bioreactor system and rabbit airway model, these stents display higher corrosion resistance and better in vivo degradation without affecting growth of rabbit airway.

3D printing of various biomaterials including titanium and stainless steel has been studied for treating patients with cranio-maxillofacial bone defect. The potential long term complications with use of inert biometals have opened the opportunities for use of biodegradable metals in the clinical arena. The authors previously reported that binder-jet 3D printing technique enhanced the degradation rates of biodegradable Fe-Mn alloy by creating engineered micropores rendering the system attractive as biodegradable implantable devices. In the present study, the authors employed CALPHAD modeling to systematically study and modify the Fe-Mn alloy composition to achieve enhanced degradation rates. Accordingly, Ca and Mg addition to Fe-35 wt% Mn solid solution predicted increase in degradation rates. In order to validate the CALPHAD results, Fe – (35 − y) wt% Mn – y wt% X (X = Ca, Mg, and y = 0, 1, 2) were synthesized by using high energy mechanical alloying (HEMA). Sintered pellets of Fe-Mn-Ca and Fe-Mn-Mg were then subjected to potentiodynamic polarization (PDP) and live/dead cell viability tests. Sintered pellets of Fe-Mn, Fe-Mn-Ca, and Fe-Mn-Mg also exhibited MC3T3 murine pre-osteoblast cells viability in the live/dead assay results. Fe-Mn and Fe-Mn-1Ca were thus accordingly selected for 3D printing and the results further confirmed enhanced degradation of Ca addition to 3D printed constructs validating the theoretical and alloy development studies. Live/dead and MTT cell viability results also confirmed good cytocompatibility of the 3D-printed Fe-Mn and Fe-Mn-1Ca constructs. Statement of Significance Bone grafting is widely used for the treatment of cranio-maxillofacial bone injuries. 3D printing of biodegradable Fe alloy is anticipated to be advantageous over current bone grafting techniques. 3D printing offers the fabrication of precise and tailored bone grafts to fit the patient specific bone defect needs. Biodegradable Fe alloy is a good candidate for 3D printing synthetic grafts to regenerate bone tissue without eliciting complications. CALPHAD theoretical models were used to develop new Fe-Mn-Ca/Mg alloys to enhance the degradation rates of traditional Fe-Mn alloys. In vitro experimental results also showed enhanced degradation rates and good cytocompatibility of sintered Fe-Mn-Ca/Mg compacts. 3D printing of Fe-Mn and Fe-Mn-1Ca alloys further demonstrated their feasibility as potentially viable bone grafts for the future.

Biphasic mixtures of crystalline β-tricalcium magnesium phosphate (β-TCMP) and an amorphous calcium magnesium phosphate have been synthesized and reported to support enhanced hMSC differentiation in comparison to β-tricalcium phosphate (β-TCP) due to the release of increased amounts of bioactive ions. In the current study, completely amorphous β-TCMP has been synthesized which is capable of releasing increased amounts of Mg(2+) and PO4(3-) ions, rather than a biphasic mixture as earlier reported. The amorphous phase formed was observed to crystallize between temperatures of 400-600°C. The scaffolds prepared with amorphous β-TCMP were capable of supporting enhanced hMSC proliferation and differentiation in comparison to commercially available β-TCP. However, a similar gene expression of mature osteoblast markers, OCN and COL-1, in comparison to biphasic β-TCMP was observed. To further study the role of Mg(2+) and PO4(3-) ions in regulating hMSC osteogenic differentiation, the capability of hMSCs to mineralize in growth media supplemented with Mg(2+) and PO4(3-) ions was studied. Interestingly, 5mM PO4(3-) supported mineralization while the addition of 5mM Mg(2+) to 5mM PO4(3-) inhibited mineralization. It was therefore concluded that the release of Ca(2+) ions from β-TCMP scaffolds also plays a role in regulating osteogenic differentiation on these scaffolds and it is noted that further work is required to more accurately determine the exact role of Mg(2+) in regulating hMSC osteogenic differentiation.

Biodegradable magnesium (Mg) alloys exhibit improved mechanical properties compared to degradable polymers while degrading in vivo circumventing the complications of permanent metals, obviating the need for surgical removal. This study investigated the safety and efficacy of Mg-Y-Zn-Zr-Ca (WZ42) alloy compared to non-degradable Ti6Al4V over a 14-week follow-up implanted as pins to fix a full osteotomy in rat femurs and as wires wrapped around the outside of the femurs as a cerclage. We used a fully load bearing model allowing implants to intentionally experience realistic loads without immobilization. To assess systemic toxicity, blood cell count and serum biochemical tests were performed. Livers and kidneys were harvested to observe any accumulation of alloying elements. Hard and soft tissues adjacent to the fracture site were also histologically examined. Degradation behavior and bone morphology were determined using micro-computed tomography scans. Corrosion occurred gradually, with degradation seen after two weeks of implantation with points of high stress observed near the fracture site ultimately resulting in WZ42 alloy pin fracture. At 14 weeks however, normal bone healing was observed in femurs fixed with the WZ42 alloy confirmed by the presence of osteoid, osteoblast activity, and new bone formation. Blood testing exhibited no significant changes arising from the WZ42 alloy compared to the two control groups. No recognizable differences in the morphology and more importantly, no accumulation of Mg, Zn, and Ca in the kidney and liver of rats were observed. These load bearing model results collectively taken, thus demonstrate the feasibility for use of the Mg-Y-Zn-Zr-Ca alloy for long bone fracture fixation applications.

Bone tissue engineering requires the upregulation of several regenerative stages, including a critical early phase of angiogenesis. Previous studies have suggested that a sequential delivery of platelet-derived growth factor (PDGF) to bone morphogenetic protein-2 (BMP-2) could promote angiogenic tubule formation when delivered to in vitro cocultures of human umbilical vein endothelial cells (HUVECs) and human mesenchymal stem cells (hMSCs). However, it was previously unclear that this PDGF to BMP-2 delivery schedule will result in cell migration into the scaffolding system and affect the later expression of bone markers. Additionally, a controlled delivery system had not yet been engineered for programmed sequential presentation of this particular growth factor. By combining alginate matrices with calcium phosphate scaffolding, a programmed growth factor delivery schedule was achieved. Specifically, a combination of alginate microspheres, alginate hydrogels, and a novel blend of resorbable calcium phosphate-based cement (ReCaPP) was used. PDGF and BMP-2 were sequentially released from this hybrid calcium phosphate/alginate scaffold with the desired 3-day overlap in PDGF to BMP-2 delivery. Using a three-dimensional coculture model, we observed that this sequence of PDGF to BMP-2 delivery influenced both cellular infiltration and alkaline phosphatase (ALP) expression. It was found that the presence of early PDGF delivery increased the distance of cell infiltration into the calcium phosphate/alginate scaffolding in comparison to early BMP-2 delivery and simultaneous PDGF+BMP-2 delivery. It was also observed that hMSCs expressed a greater amount of ALP+ staining in response to scaffolds delivering the sequential PDGF to BMP-2 schedule, when compared with scaffolds delivering no growth factor, or PDGF alone. Importantly, hMSCs cultured with scaffolds releasing the PDGF to BMP-2 schedule showed similar amounts of ALP staining to hMSCs cultured with BMP-2 alone, suggesting that the sequential schedule of PDGF to BMP-2 presentation promotes differentiation of hMSCs toward an osteoblast phenotype while also increasing cellular infiltration of the scaffold.

Magnesium phosphate implants may be used for bone void filling applications, potentially replacing traditionally studied bioceramics, which suffer from limited resorption and inferior mechanical properties compared to natural bone. In this study, amorphous and crystalline trimagnesium phosphates were synthesized and characterized utilizing a variety of analytical methods. In vitro solubility and cytotoxicity of the corresponding amorphous and crystalline phosphates were also analyzed. Amorphous magnesium phosphate was shown to be more soluble than the crystalline counterpart in vitro while inducing mineralization of an amorphous phosphate phase mimicking hydroxyapatite-type characteristic morphology on the substrate surface. The rapid mineralization of the amorphous magnesium phosphate was found to promote the proliferation and differentiation of osteoblast-like cells in comparison to the crystalline phase. Both magnesium phosphates hindered the differentiation of monocytes into osteoclasts. The combined effects of the spontaneous serum-mediated apatite-like mineralization, increased osteoblast differentiation and suspended osteoclast formation indicate that the amorphous magnesium phosphates may be promising bioactive materials for bone void repair applications.

Existing energy resources are struggling to cope with the current energy requirements. It is therefore, necessary to increase energy efficiency and reduce greenhouse gases emissions in integrated steel industries. The yield of coking by-products is one of the key ways to achieve these goals. This review article is focused on history of the by-products such as coal tar, coal tar pitch, ammonia, hydrogen sulphide, pyridine, hydrogen cynide and carbon based material. Different technology for removal of mentioned by-products are briefly described according to technology development at different stage. Yield and quality of coking byproducts, its impacts on carbonization processes and factors such as volatile matter, rank of coal, reactive macerals, elemental constituents, and temperature were also investigated.

This study examines the influence of national culture on various facets of a country's sustainability indicators, namely environmental performance, human development, and the avoidance of corruption. At the outset, using exploratory factor analysis from data from 57 countries from the GLOBE cultural practices, we identify three dimensions of culture: performance based culture (PBC), socially supportive culture (SSC) and gender egalitarianism culture (GEC). Then, using hierarchical regression analyses, we explore the role of cultural and economic factors on the various facets of sustainability. Specifically, we find that both PBC and GEC positively influence the environmental performance, even after controlling for wealth of a nation, i.e., GDP. GEC interacts with economic freedom in positively influencing environmental performance. GEC also positively influences human development as does GDP and economic growth rate. Interaction effects are also explored. We finally summarize the implications of the dimensions of culture and economic factors on the sustainability factors, and provide suggestions for future research.

BACKGROUND: Manual small incision cataract surgery is a simple and less expensive technique of cataract surgery but gives visual result almost equivalent to Phacoemulsification. PURPOSE: To compare surgery induced astigmatism in manual small incision cataract surgery through superior and temporal approaches. METHODOLOGY: One hundred and thirty eyes were included in this study. Eyes with steeper vertical keratometric reading were subjected to superior small incision cataract surgery (SICS) and those with a steeper horizontal keratometric reading were subjected to temporal small incision cataract surgery (SICS). Eyes with no astigmatism were randomly subjected to either type of surgery. Each group had 65 eyes. All the patients were followed up on 1 st , 7 th , 30 th and 90 th postoperative days. During each follow up, UCVA and BCVA were recorded, slit lamp examination was performed; autorefractometry and keratometric examinations were also performed. RESULTS: Out of 65 in the temporal incision group only 55 completed follow up till 90th day. The mean surgery induced astigmatism was found to be 1.45 ± 0.4 D in superior and 0.70 ± 0.3 D in the temporal incision group. Amount of surgery induced astigmatism was found to be significantly lower among the temporal incision group (t = 11.444, p = 0.000). CONCLUSION: SICS through temporal approach provides a better stabilization of refraction with significantly lesser amount of SIA than superior approach.

Additive manufacturing presents opportunities to treat bone defects using biomimetic tissue scaffolds. Past investigations have explored modulating scaffold mechanical properties through varying materials and geometric motifs. Herein, we applied the rotated plywood structure of bone tissue to a 3D printed scaffold with the goal of improving mechanical performance compared to an orthogonal mesh design commonly used in tissue scaffold applications. The scaffolds were subjected to uniaxial compression followed by scanning electron microscopy and microcomputer tomography. The uniaxial compression test was characterized through elastic modulus (mean 1.32 GPa biomimetic, 0.196 GPa orthogonal, p < 0.001), ultimate compressive strength (mean 16.546 MPa biomimetic, 6.309 MPa orthogonal design, p < 0.001), and ultimate compressive strain values (4.867% biomimetic, 9.000% orthogonal, p < 0.005). Correlation of microfracture imaging to bulk scaffold mode of failure suggest that utilizing the biomimetic plywood design not only improved mechanical performance, but also reduced asymmetrtic buckling, plastic deformation, and fracture propagation similar to bone tissue.

Here we present a method of QT interval meas-urement for Physionet's online QT Challenge ECG database using the combination of wavelet and time plane feature extraction mechanisms. For this we mainly combined two previous works one done using the Daubechies 6 wavelet and one time plane based with modifications in their algorithms and inclusion of two more wavelets (Daubechies 8 and Symlet 6). But found that out of these three wavelets Daube-chies 6 and 8 gives the best output and when averaged with the interval of time plane feature extraction method it gives least percentage of error with respect to the median reference QT interval as specified by Physionet. Our modified time plane feature extraction scheme along with the wavelet method together produces best re-sults for automated QT wave measurement as its regular verification is important for analyzing cardiac health. For the V2 chest lead particularly whose QT wave is of tremendous significance we have tested on 530 recordings of Physionet. This is because delay in cardiac repolarization causes ventricular tachyarrhythmias as well as Torsade de pointes (TdP). A feature of TdP is pronounced prolongation of the QT interval in the supraventricular beat preceding the ar-rhythmia. TdP can degenerate into ventricular fibrillation, leading to sudden death.

A series of tri- and di-organotin(IV) derivatives of the types R3SnL, R2SnL2 and [(R2SnL)2O]2 have been synthesized by the reaction of tri- and di-organotin(IV) chloride(s) with sodium cyclopropane carboxylate and sodium 3-cyclohexylpropanoate. Based on spectroscopic evidence (IR and NMR), all the triorganotin carboxylates were found to be penta-coordinated in the solid state (except the tricyclohexyltin derivative, which was found to be four-coordinated) and four-coordinated in the solution state. Attempted reaction of Me2SnCl2 with sodium cyclopropane carboxylate in 1:2 stoichiometry afforded a bis(dicarboxylato tetraorganodistannoxane) complex, {[Me2Sn(cyclo-CH2)2CHCOO]2O}2. The X-ray diffraction of this ‘dimethyltin(IV) complex’ shows that the compound possesses a tetranuclear aggregate with one bridging bidentate and other free organic ester type monodentate carboxylate groups in which each Sn atom has a five-coordinated geometry. These complexes were also screened for their antifungal activities. Copyright © 2008 John Wiley & Sons, Ltd.

Aims To report the 6-year incidence of, and risk factors for, cardiovascular disease (CVD), either coronary disease or stroke, in previously hospitalized African-Americans with Type 1 diabetes mellitus. Methods African-Americans (n = 483) with Type 1 diabetes were re-examined as part of a 6-year follow-up. At both visits, patients underwent a structured clinical interview, which included history of either coronary disease or stroke, ocular examination and masked grading of seven stereoscopic fundus photographs, blood pressure measurements, and administration of the Beck Depression Inventory. Biological measurements included blood and urine assays. Results Of the 483 patients who had a 6-year follow-up, 449 had no evidence of CVD at the baseline examination. Of these 449 patients, 51 (11.4%) developed any CVD—42 (9.3%) coronary disease and 14 (3.1%) a stroke. Six-year incidence of any CVD was significantly associated with older age (P

Background: Myopia is one of the most common causes of visual impairment worldwide.It is proved in earlier studies that the eye shape is different in myopic and nonmyopic children even at a very young age, with the former manifesting asymmetric axial globe elongation and the latter global expansion but limited information is available regarding hypermetropia. Aim: To find out the variations of axial ocular dimensions in relation to age, sex, height and to demonstrate any possible correlation of body mass index (BMI) in myopic hypermetropic and emmetropic patients. Settings: It is a cross-sectional observational study. Materials and Methods: All the patients attending eye OPD in the Regional Institute of Ophthalmology (R.I.O.), Medical College, Kolkata, West Bengal, India from June2010 to May 2011.Axial dimensions were measured by B-mode USG. Refractive status was measured.Age, gender, height and BMI were also observed. After collecting all the data,all the variables were summarised by descriptive statistics followed by correlation testing by Pearson’s Correlation Coefficient r. Results: Height was positively correlated with axial length, anterior chamber depth, vitreous chamber depth ;age was positively correlated with axial length, vitreous chamber depth and negatively correlated with anterior chamber depth. Subjects with higher BMI tended to had refractions that were more hypermetropic. Conclusion: The findings of the present study can highlight not only the normal range of the different ocular parameters namely axial length, anterior chamber depth, vitreous chamber depth and lens thickness but their variation with age, gender, height and weight.

We report the first stage of a genome scan of schizophrenia (SZ) and bipolar disorder (BP) covering 18 candidate chromosomal areas. In addition to testing susceptibility loci that are specific to each disorder, we tested the hypothesis that some susceptibility loci might be common to both disorders. A total of 480 individuals from 21 multigenerational pedigrees of Eastern Québec were evaluated by means of a consensus best-estimate diagnosis made blind to diagnoses in relatives and were genotyped with 220 microsatellite markers. Two-point and multipoint model-based linkage analyses were performed and mod scores (Z, for max Z(max)) are reported. The strongest linkage signals were detected at D18S1145 (in 18q12; Z = 4.03) for BP, and at D6S334 (in 6p 22-24; Z(het) = 3.47; alpha = 0.66) for SZ. Three other chromosomal areas (3q, 10p, and 21q) yielded linkage signals. Chromosomes 3p, 4p, 5p, 5q, 6q, 8p, 9q, 11q, 11p, 12q, 13q, 18p and 22q showed no evidence of linkage. The 18q12 results met the Lander and Kruglyak (1995) criterion for a genome-wide significant linkage and suggested that this susceptibility region may be shared by SZ and BP. The 6p finding provided confirmatory evidence of linkage for SZ. Our results suggest that both specific and common susceptibility loci must be searched for SZ and BP.

Background: Agartala is one of the fastest growing cities in India. With rapid increase in the number of bikes and other motor vehicles, road traffic accidents (RTA) are also increasing sharply. Ocular trauma and resultant ophthalmic morbidities following RTA is common. Aims & Objective: To study the epidemiology and pattern of ocular trauma among the road traffic accident cases. Materials and Methods: A hospital based study was conducted during February to July 2013 among 700 road traffic cases attending Ophthalmology and Casualty Department of Agartala Govt. Medical College, Tripura. Descriptive statistics and chi square test were used for presenting data. Results: Out of 700 RTA patients 82.86% (580) were male and 17.14% (120) were female. Majority i.e. 76% (532) of the RTA cases occurred among the two- wheeler users, 42 (35.29 %) were drunk and 17% (119) of the RTA cased sustained ocular injuries. Among the ocular injury cases, 60% (72) suffered from ecchymosis. Out of 119 RTAs with ocular injuries, 22 (18.48%) had no PL at reporting due to due to ocular nerve injury and all of them failed to recover even after treatment. Conclusion: Two-wheeler accident is common and an important cause for loss of vision following RTA. Victims of RTA reporting with loss of vision due to optic nerve injury had poor visual prognosis. Hence, primary preventive approach through behaviour change communication among the bikers for promoting safe riding practices and strict implementation of traffic rules like riding at safe speed, wearing helmet and avoiding alcohol before driving are needed to prevent RTA associated blindness.

Syntheses of methyl 2-O-beta-L-rhamnopyranosyl-beta-D-galactopyranoside (9), methyl 2-O-alpha-L-rhamnopyranosyl-beta-D-galactopyranoside (13), and methyl 4-O-beta-D-glucopyranosyl-2-O-alpha-L-rhamnopyranosyl-beta-D- galactopyranoside (16) in good yields are described. Both 13 and 16 significantly inhibit antigen-antibody precipitation in the S. pneumoniae Type 23 immune system. The results indicate that the rhamnosyl group in the side chain of the repeating unit of the antigen is alpha and not beta as reported previously, and that the trisaccharide related to 16 is the immunodominant group.

This paper reports the reaction of SnMe2Cl2 with adenosine, guanosine and inosine in aqueous solution at pH 4.5. The nucleosides give probably polymeric species in which there is monodentate coordination to O2′ of the ribose ring as indicated by 80 MHz PMR.

The syntheses of the complexes formulated as SnMe2Cl2(Ad)2 (I), SnMe2Cl2(Ado)2 (II), SnMe2Cl2- (9-MeAd)2 (III) [Ad = adenine, Ado = adenosine, 9-MeAd = 9-methyladenine] as well as the more unexpected SnPhCl2(OH)(Ad)2·3H2O (IV) and SnPhCl3(Ado)2 (V) by reaction of SnMe2Cl2 or SnPh2Cl2 with the appropriate bases in methanol is described. 1H NMR studies suggest that coordination is through the N-7 position of the adenine base.

Preparation et donnees IR et RMN de Cp 2 Ti(OCOC 6 H 4 NH 2 ) 2 CpTi(Cl)(SCH 2 CHNH 2 OCO)•2H 2 O et Cp 2 Ti(OCOCH 2 NHCOC 6 H 5 ) 2

The capsular polysaccharide from Streptococcus pneumoniae Type 23 (S-23) was found to contain D-galactose, D-glucose, L-rhamnose, glycerol, and phosphorus in the ratios of 1:1:2:0.6:1. Methylation analysis provided information about the linkages of the different sugar units. The sequence of the different sugar residues was confirmed by Smith degradation. Oxidation of S-23 with chromium trioxide indicated that all of the sugar units have the beta configuration. The results suggest the following structure for the repeating unit. (formula; see text)