Biomedical subjects

John C Russell

Publications and source records attributed to John C Russell.

3 recordsLinked to original sources

PubMed2005

Ampelomyces mycoparasites from apple powdery mildew identified as a distinct group based on single-stranded conformation polymorphism analysis of the rDNA ITS region.

Pycnidial fungi belonging to the genus Ampelomyces are the most common natural antagonists of powdery mildews worldwide. During a study of the interactions between apple powdery mildew (Podosphaera leucotricha) and Ampelomyces mycoparasites, 52 new Ampelomyces isolates were obtained from P. leucotricha and, in addition, 13 new isolates from other species of the Erysiphaceae in four European countries. Their genetic diversity was screened using single-stranded conformation polymorphism (SSCP) analysis of the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA). For comparison, 24 isolates obtained from genetic resource collections or other sources were included in this study. Based on the ITS-SSCP patterns, the isolates were placed in eight groups. The isolates belonged to two types based on their growth in culture. The faster-growing and the slower-growing isolates were included in different SSCP groups. A phylogenetic analysis of the ITS sequences of representatives of these groups confirmed the results obtained with the SSCP method, and showed that the faster-growing isolates do not belong to Ampelomyces as suggested by earlier studies. All the isolates from P. leucotricha fell into a distinct SSCP group of genetically homogeneous isolates. This suggests that Ampelomyces mycoparasites which occur in apple powdery mildew are slightly different from the other Ampelomyces groups which contain mycoparasites from various powdery mildew species. This may be because the main growth period of Ampelomyces mycoparasites in apple powdery mildew is isolated in time from that of Ampelomyces isolates that occur in other species of the Erysiphaceae. P. leucotricha starts its life-cycle early in the season, usually in March-April, while most powdery mildews are active in the same environments only late in the year.

Ascomycota↗

PubMedDate not supplied

Ethnic differences in symptoms of post-traumatic stress after the Exxon Valdez oil spill.

INTRODUCTION: Previous studies have reported ethnic differences in the prevalence of post-traumatic stress disorder (PTSD), but the reasons for these differences remain unclear. HYPOTHESIS: Ethnic differences in the prevalence of PTSD may reflect ethnic differences in (1) exposure to traumatic events; (2) appraisal of such event as traumatic; and (3) culturally-determined responses to standardized diagnostic instruments, reflecting differences in cultural meanings associated with physical symptoms and idioms of distress. METHODS: Ethnic differences in risk factors and factor structures of PTSD symptoms were examined in 188 Alaskan Natives and 371 Euro-Americans exposed to the Exxon-Valdez oil spill in 1989. RESULTS: High levels of social disruption were associated with PTSD one year after the oil spill in both ethnic groups. However, low family support, participation in spill clean-up activities, and a decline in subsistence activities were significantly associated with PTSD in Alaskan Natives, but not in Euro-Americans. Factor analysis of the Diagnostic Interview Schedule PTSD subscale revealed five factors for both ethnic groups. However, the items comprising these factors were dissimilar. CONCLUSIONS: These results suggest that social disruption is sufficiently traumatic to be associated with symptoms of post-traumatic stress, but that a diagnosis of PTSD must take into consideration local interpretations of these symptoms.

Adult↗

PubMedDate not supplied

Solid phase assembly of defined protein conjugates.

We have developed a solid-phase procedure for protein-protein conjugation that gives greater control over product size and composition than previous methods. Conjugates are assembled by sequential addition of activated proteins to the support under conditions suitable for maintaining the activity of the proteins. The total number of conjugate units to be prepared is fixed in the first step by the quantity of the first protein absorbed by the support. In each following step, the added protein links only to previously bound protein. The final conjugate is released to solution by cleaving the linker holding the first protein to the support. This stepwise assembly provides uniformly sized conjugates of the desired size and composition with placement of components at the desired positions within the structure. Using this approach, we have prepared a series of conjugates containing R-phycoerythrin as the central protein, with varying quantities of alkaline phosphatase and IgG with expected molecular masses ranging from 1.6 to 11.5 MDa. Size-exclusion chromatography and atomic force microscopy demonstrate homogeneity and control of the conjugate size. In an immunoassay for human thyroid stimulating hormone, the conjugates show signals consistent with their compositions.

Alkaline Phosphatase↗