58 research outputs found
Pneumococcal conjugate vaccine given shortly after birth stimulates effective antibody concentrations and primes immunological memory for sustained infant protection.
BACKGROUND: In developing countries, newborn immunization with pneumococcal conjugate vaccines (PCVs) could protect young infants who are at high risk of invasive pneumococcal disease (IPD) but might lead to immune tolerance. METHODS: In a randomized trial, young infants received 7-valent PCV at 6, 10, and 14 weeks (Expanded Programme on Immunization [EPI] group) or 0, 10, and 14 weeks (newborn group). Safety was monitored actively at 2-7 days and then passively. Serum samples obtained at birth and 6, 10, 14, 18, 36, and 37 weeks were assayed by enzyme-linked immunosorbent assay for anticapsular immunoglobulin G concentration and avidity. Infants were boosted with either 7-valent PCV or one-fifth dose of pneumococcal polysaccharide vaccine at 36 weeks. Nasopharyngeal swab samples were obtained at 18 and 36 weeks. RESULTS: Three-hundred neonates and young infants were enrolled. Newborn vaccination was well tolerated. Adverse events occurred equally in each group; none was related to immunization. One infant, immunized at birth, died of unrelated neonatal sepsis. At 18 weeks, protective concentrations (â„0.35 ÎŒg/mL) were achieved against each serotype by â„87% of infants with no significant differences between groups. Geometric mean concentrations were higher in the EPI group for serotypes 4, 9V, 18C, and 19F at 18 weeks and for serotype 4 at 36 weeks. Avidity was greater in the newborn group for serotypes 4, 6B, and 19F at 18 weeks and for serotype 19F at 36 weeks. Booster responses and vaccine-type/nonvaccine-type carriage prevalence did not differ between groups. CONCLUSIONS: PCV was safe, immunogenic, and primed for memory when given at birth. There was no evidence of immune tolerance. Vaccination beginning at birth offers an alternative to control IPD in vulnerable young infants
Lewis Base Mediated ÎČ-Elimination and Lewis Acid Mediated Insertion Reactions of Disilazido Zirconium Compounds
The reactivity of a series of disilazido zirconocene complexes is dominated by the migration of anionic groups (hydrogen, alkyl, halide, OTf) between the zirconium and silicon centers. The direction of these migrations is controlled by the addition of two-electron donors (Lewis bases) or two-electron acceptors (Lewis acids). The cationic nonclassical [Cp2ZrN(SiHMe2)2]+ ([2]+) is prepared from Cp2Zr{N(SiHMe2)2}H (1) and B(C6F5)3 or [Ph3C][B(C6F5)4], while reactions of B(C6F5)3 and Cp2Zr{N(SiHMe2)2}R (R = Me (3), Et (5), n-C3H7 (7), CHâCHSiMe3 (9)) provide a mixture of [2]+ and [Cp2ZrN(SiHMe2)(SiRMe2)]+. The latter products are formed through B(C6F5)3 abstraction of a ÎČ-H and R group migration from Zr to the ÎČ-Si center. Related ÎČ-hydrogen abstraction and X group migration reactions are observed for Cp2Zr{N(SiHMe2)2}X (X = OTf (11), Cl (13), OMe (15), O-i-C3H7 (16)). Alternatively, addition of DMAP (DMAP = 4-(dimethylamino)pyridine) to [2]+ results in coordination to a Si center and hydrogen migration to zirconium, giving the cationic complex [Cp2Zr{N(SiHMe2)(SiMe2DMAP)}H]+ ([19]+). Related hydrogen migration occurs from [Cp2ZrN(SiHMe2)(SiMe2OCHMe2)]+ ([18]+) to give [Cp2Zr{N(SiMe2DMAP)(SiMe2OCHMe2)}H]+ ([22]+), whereas X group migration is observed upon addition of DMAP to [Cp2ZrN(SiHMe2)(SiMe2X)]+ (X = OTf ([12]+), Cl ([14]+)) to give [Cp2Zr{N(SiHMe2)(SiMe2DMAP)}X]+ (X = OTf ([26]+), Cl ([20]+)). The species involved in these transformations are described by resonance structures that suggest ÎČ-elimination. Notably, such pathways are previously unknown in early metal amide chemistry. Finally, these migrations facilitate direct SiâH addition to carbonyls, which is proposed to occur through a pathway that previously had been reserved for later transition metal compounds
Effect of Integrated Employee Training on Sustainable Mobility of Matatu Saccos in Public Transport Sector in Nairobi County, Kenya
This study was carried out to assess the effect of
integrated employee training on sustainable mobility of Matatu
Sacco in public transport sector in Nairobi County. Training in
transport sector is of paramount importance as it makes the
drivers more responsible which in turn reduces road accident,
vehicle maintenance and enhances proper handling of
passengers and creates an improved public image for the sector.
The study comprised of 177 Sacco Managers representing all the
Matatu Sacco registered by NTSA in Nairobi County in
2015.NTSA, 2015. The study was guided by positivism
philosophy where census was applied and adopted mixed
method research design. Data from the Sacco Managers was
collected using a structured questionnaire, while an interview
schedule was used for the representatives from both the MoT
and VOA. Data was analyzed using descriptive and inferential
statistics, and the results revealed that influence of integrated
employee training, had significant influence on sustainable
mobility of Matatu Saccos in public transport sector in Nairobi
County, Kenya. The results also revealed that there has been
training of simple technical skills, such as, maintenance of
vehicles and first aid to the drivers. It can be concluded that
training drivers on safety improves public image in Matatu
Saccos. Recommendations can be made that it is important to
conduct training needs assessment before training employees to
ensure missing gaps or mismatch on the skills are well filled or
captured to ensure training objectives are achieved effectively.
This would enable both the ministry of transport and Sacco
management to develop competent training programs for its
employees
Unsupported boronâcarbon Ï-coordination to platinum as an isolable snapshot of Ï-bond activation
Ï-Complexes of transition metalsâkey intermediates in metal-mediated bond activation and homogeneous catalysisâhave traditionally been isolable only when chelating or when one of the participating atoms is hydrogen. Here, by treating the Lewis-basic transition metal complex [Pt(PEt3)4] with an electron-poor borirene, we isolate a complex with an unsupported borirene ligand bound, not through the unsaturated C=C bond, but exclusively via a BâC single bond. Using NMR spectroscopy, X-ray crystallography and density functional theory calculations, we show, herein, that coordination of the borirene ligand is based on electron donation from the BâC Ï bond to the metal, aided by a strong Pt-to-B dative interaction. The complex is the first isolable non-agostic Ï-complex featuring two p-block elements and has broad implications as a model for the metal-mediated activation of strong p-block-p-block Ï-bonds
Interplay between Theory and Experiment: Computational Organometallic and Transition Metal Chemistry
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