51 research outputs found
A Study of Formal and Informal Mentoring in the United States Air Force
Mentoring has been identified as a significant contributor to employee performance and development. Debate has come about as result of implementation of formal mentoring programs where mentors are assigned to protĂ©gĂ©s as opposed to informal relationship formed out of mutual respect and liking. Secondary data, including measures of leader member exchange, similarity, contact time, and others, were used from a 1998 survey of company grade officers (protĂ©gĂ©s) and their formal and informal mentors. Analysis of Variance compared mean values between formally and informally mentored protĂ©gĂ©s. Additionally, a logistic regression was used to understand the impact that different measures had on the protĂ©gĂ©âs decision to identify an informal mentor. Leader Member Exchange, Similarity, Contact Time, and Military Status (active duty versus civilian) all were identified as having a significant impact on a protĂ©gĂ©s decision to identify an informal mentor. Since the United States Air Force has implemented a formal mentoring program this study offers suggestions of ways which formal relationships can be improved. By focusing on leader member exchange concepts supervisors can become more successful formal mentors. Additionally, Air Force members should also be encouraged to engage in informal mentoring relationships in order to fully capitalize upon the benefits of mentoring
A Phase II, Randomized Study on an Investigational DTPw-HBV/Hib-MenAC Conjugate Vaccine Administered to Infants in Northern Ghana
BACKGROUND: Combining meningococcal vaccination with routine immunization in infancy may reduce the burden of meningococcal meningitis, especially in the meningitis belt of Africa. We have evaluated the immunogenicity, persistence of immune response, immune memory and safety of an investigational DTPw-HBV/Hib-MenAC conjugate vaccine given to infants in Northern Ghana. METHODS AND FINDINGS: In this phase II, double blind, randomized, controlled study, 280 infants were primed with DTPw-HBV/Hib-MenAC or DTPw-HBV/Hib vaccines at 6, 10 and 14 weeks of age. At 12 months of age, children in each group received a challenge dose of serogroup A+C polysaccharides. Antibody responses were assessed pre, and one month-post dose 3 of the priming schedule and pre and 1 month after administration of the challenge dose. One month post-dose 3, 87.8% and 88.2% of subjects in the study group had bactericidal meningococcal serogroup A (SBA-MenA) and meningococcal serogroup C (SBA-MenC) antibody titres > or = 1:8 respectively. Seroprotection/seropositivity rates to the 5 antigens administered in the routine EPI schedule were non-inferior in children in the study group compared to those in the control group. The percentages of subjects in the study group with persisting SBA-MenA titres > or = 1:8 or SBA-MenC titres > or = 1:8 at the age of 12 months prior to challenge were significantly higher than in control group (47.7% vs 25.7% and 56.4% vs 5.1% respectively). The administration of 10 microg of serogroup A polysaccharide increased the SBA-MenA GMT by 14.0-fold in the DTPW-HBV/HibMenAC-group compared to a 3.8 fold increase in the control-group. Corresponding fold-increases in SBA-MenC titres following challenge with 10 microg of group C polysaccharide were 18.8 and 1.9 respectively. Reactogenicity following primary vaccination or the administration of the challenge dose was similar in both groups, except for swelling (Grade 3) after primary vaccination which was more frequent in children in the vaccine than in the control group (23.7%; 95%CI [19.6-28.1] of doses vs 14.1%; 95% CI [10.9-17.8] of doses). Fifty-nine SAEs (including 8 deaths), none of them related to vaccination, were reported during the entire study. CONCLUSIONS: Three dose primary vaccination with DTPw-HBV/Hib-MenAC was non-inferior to DTPw-HBV/Hib for the 5 common antigens used in the routine EPI schedule and induced bactericidal antibodies against Neisseria meningitidis of serogroups A and C in the majority of infants. Serogroup A and C bactericidal antibody levels had fallen below titres associated with protection in nearly half of the infants by the age of 12 months confirming that a booster dose is required at about that age. An enhanced memory response was shown after polysaccharide challenge. This vaccine could provide protection against 7 important childhood diseases (including meningococcal A and C) and be of particular value in countries of the African meningitis belt. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN35754083
Sequence Analysis of the rfb Loci, Encoding Proteins Involved in the Biosynthesis of the Salmonella enterica O17 and O18 Antigens: Serogroup-Specific Identification by PCR
We report sequencing of the O antigen encoded by the rfb gene cluster of Salmonella enterica serotype Jangwani (O17) and Salmonella serotype Cerro (O18). We developed serogroup O17- and O18-specific PCR assays based on rfb gene targets and found them to be sensitive and specific for rapid identification of Salmonella serogroups O17 and O18
Molecular Analysis of the rfb O Antigen Gene Cluster of Salmonella enterica Serogroup O:6,14 and Development of a Serogroup-Specific PCR Assay
The Kauffmann-White scheme for serotyping Salmonella recognizes 46 somatic (O) antigen groups, which together with detection of the flagellar (H) antigens form the basis for serotype identification. Although serotyping has become an invaluable typing method for epidemiological investigations of Salmonella, it does have some practical limitations. We have been characterizing the genes required for O and H antigen biosynthesis with the goal of developing a DNA-based system for the determination of serotype in Salmonella. The majority of the enzymes involved in O antigen biosynthesis are encoded by the rfb gene cluster. We report the sequencing of the rfb region from S. enterica serotype Sundsvall (serogroup O:6,14). The S. enterica serotype Sundsvall rfb region is 8.4 kb in length and comprises six open reading frames. When compared with other previously characterized rfb regions, the serogroup O:6,14 sequence is most related to serogroup C(1). On the basis of DNA sequence similarity, we identified two genes from the mannose biosynthetic pathway, two mannosyl transferase genes, the O unit flippase gene and, possibly, the O antigen polymerase. The whole cluster is derived from a low-G+C-content organism. Comparative sequencing of an additional serogroup O:6,14 isolate (S. enterica serotype Carrau) revealed a highly homologous sequence, suggesting that O antigen factors O:24 and O:25 (additional O factors associated with serogroup O:6,14) are encoded outside the rfb gene cluster. We developed a serogroup O:6,14-specific PCR assay based on a region of the putative wzx (O antigen flippase) gene. This provides the basis for a sensitive and specific test for the rapid identification of Salmonella serogroup O:6,14
Febre purpĂșrica brasileira, virulĂȘncia em modelo animal do Haemophilus Aegyptius (H. influenzae biogrupo aegyptius)
Brazilian purpuric fever (BPF) is caused by invasive strains of Haemophilus aegyptius (H.influenzae biogroup aegyptius, Hae). These strains were differentiated from Hae strains associated only with conjunctivitis (non-invasive Hae strains) through specific molecular markers. Complement-depleted infant rat model was used to study the invasive and non-invasive Hae strains to compare their virulence potential. Inoculating 10(5) bacteria in the rats, the invasive strains caused 80 to 100% bacteremia and the intensity of bacteremia was 10(2,5±0,49) to >; 10(4,69) cfu/ml of blood. Using the same infectious dose, the non-invasive strains did not cause frequent bacteremia (0 to 50%) and the intensity was 0 to 10(3,69±0,53) cfu/ml of blood. The infectious doses able to cause 50% of bacteremia in the rats (BD 50%) varied from ; 10(7,3) bacteria for non-invasive strains. Passive immunization using antisera to invasive strains protected rats against bacteremia caused by homologous strains, but not by heterologous strain. By comparing the bacteremia caused by Hae and bacteremia caused by H. influenzae b (Eagan strain, Hib), it was demonstrated that Hib had higher virulence potential. This animal model was useful to clarify the virulence potential of invasive Hae strains.Febre PurpĂșrica Brasileira (FPB) Ă© causada por cepas invasoras de Haemophilus aegyptius (H. influenzae biogrupo aegyptius, Hae). Estas cepas invasoras foram diferenciadas de cepas de Hae associadas apenas a conjuntivites (cepas nĂŁo invasoras) atravĂ©s de marcadores moleculares especĂficos. Modelo de ratos recĂ©m nascidos depletados de complemento foi aplicado ao estudo de cepas de Hae, associadas e nĂŁo associadas a FPB, com o objetivo de se caracterizar seus potenciais de virulĂȘncia. Com dose infectante de 10(5) cĂ©lulas, as cepas invasoras causaram bacteriemia em 80-100% dos ratos inoculados,.e a magnitude da bacteriemia variou de 10(2,5±0,49) a >; 10(4,69) ufc/ml de sangue. Usando a mesma dose infectante as cepas controles nĂŁo causaram bacteriemia frequente (0 a 50%) e a magnitude variou de 0 a 10(3,69±0,53) ufc/ml de sangue. As doses infectantes capazes de causar bacteriemia em 50% dos ratos inoculados (DB50%) para as cepas invasoras de Hae variaram de ; 10(7,3) bactĂ©rias. Imunização passiva com antissoros produzidos com cepas invasoras demonstrou que os ratos foram protegidos das bacteriemias causadas pelas cepas homĂłlogas, mas nĂŁo da infecção causada pela cepa heterĂłloga. Comparando a bacteriemia causada pelas cepas de Hae com a bacteriemia causada pelo H. influenzae b, cepa Eagan (Hib), foi demonstrado o maior potencial de invasibilidade de Hib. Este modelo animal demonstrou ser Ăștil para esclarecer o maior potencial de virulĂȘncia das cepas invasoras de Hae
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