A single recombinant plasmid expressing two major outer surface proteins of the Lyme disease spirochete.

A gene bank of DNA from the Lyme disease spirochete was constructed in the plasmid pBR322. Plasmid pTRH32, a recombinant that in Escherichia coli expresses the two major outer surface proteins of the Lyme disease spirochete, was identified. One of the recombinant products, designated OspA, represents a surface protein that appears to be common to all Lyme disease spirochetes, whereas the other recombinant product, designated OspB, represents a more variable surface protein. This recombinant plasmid provides a foundation for future studies on the epidemiology and pathogenesis of Lyme disease as well as on the genetic organization of the etiologic agent.

Friendship quality and sociometric status: between-group differences and links to loneliness in severely abused and nonabused children.

OBJECTIVE: There were two main aims: first, to illuminate the difference between abused children's general popularity with classmates and success in close friendships; second, to examine the specific interactional qualities of abused children's friendships and their links to loneliness. METHOD: Thirty-five severely abused children and 43 matched, nonabused children were compared on peer-rated sociometric status, self-reported loneliness, and observed and self-reported friendship quality. RESULTS: Abused children were not rated significantly lower sociometrically, nor did they differ significantly from control children on several measures of friendship quality, such as resolving conflicts and helping each other. However, abused children were observed to be more negative and less proactive in their interactions. They also reported their friendships as being more conflictual, and as higher on betrayal and lower on caring. Only observational friendship variables predicted loneliness. CONCLUSIONS: The results challenge the assumption that abused children's peer relationships are uniformly more maladaptive than nonabused children's, and point to the possible benefits of structured interventions for "normalizing" their friendship interactions. The pattern of difficulties exhibited by abused children (e.g., conflict) provides foci for more specific interventions. Multi-method assessments are necessary and the multi-dimensional nature of children's social adjustment is important to understand.

Isolation and characterization of alkaline protease-deficient mutants of Pseudomonas aeruginosa in vitro and in a mouse eye model.

Mutants of Pseudomonas aeruginosa are described which are markedly deficient in alkaline protease production. Characterization of these mutants in vitro suggests that the mutations in two of these strains are specific for alkaline protease production. Examination of these mutants in a mouse eye model demonstrates that alkaline protease is required for the establishment of corneal infections with P. aeruginosa PA103. Mutants deficient in alkaline protease production could not colonize traumatized cornea and did not produce the corneal damage characteristic of infection by the parental strain. Addition of subdamaging amounts of alkaline protease to eyes infected with the protease-deficient mutants resulted in infections which were indistinguishable from infections caused by the parental strain.

Organization of genes encoding two outer membrane proteins of the Lyme disease agent Borrelia burgdorferi within a single transcriptional unit.

OspA and OspB are major outer membrane proteins and antigens of the Lyme disease spirochete, Borrelia burgdorferi. We examined the organization of ospA and ospB, the genes encoding these proteins. The location and direction of transcription of each osp gene was determined by subcloning, deletion analysis, and transposon Tn5 mutagenesis. Transposon Tn5 insertions within the ospA gene abrogated expression of ospB, suggesting that these genes are transcribed from a common promoter. Northern blot analysis of mRNA from B. burgdorferi with two DNA probes individually specific for ospA or ospB identified a 2.2-kilobase transcript that hybridized with each probe. These studies indicate that the two osp genes of B. burgdorferi constitute a single transcriptional unit.

Locus of the Pseudomonas aeruginosa toxin A gene.

The gene for Pseudomonas aeruginosa toxin A has been mapped in the late region of the chromosome of strain PAO. Strain PAO-PR1, which produces parental levels of toxin A antigen that is enzymatically inactive and nontoxic, was used as the donor for R68.45 plasmid-mediated genetic exchange. Strain PAO-PR1 (toxA1) was mated with toxin A-producing strains, and exconjugates for selected prototrophic markers were tested for the transfer of toxA1. The toxA1 gene was located between cnu-9001 and pur-67 at approximately 85 min on the PAO chromosome.

Heterogeneity of major proteins in Lyme disease borreliae: a molecular analysis of North American and European isolates.

We examined 46 isolates of Borrelia burgdorferi, the etiologic agent of Lyme disease and related disorders, with polyacrylamide gel electrophoresis and monoclonal antibodies. Our attention was on the OspA proteins, which are major proteins of the spirochete. There were at least four discernible phenotypes of the OspA protein. While 25 North American isolates were, with one exception, homogeneous in the type of OspA protein that they produced, 21 European isolates were heterogeneous in the types of OspA proteins represented. Only three European strains resembled North American strains in their OspA phenotype. Application of a deoxyribonucleic acid probe for an ospA gene demonstrated that the arrangement of ospA-associated sequences in the DNA differed between isolates.

Comparison of two methods of genetic exchange in determination of the genetic locus of the structural gene for Pseudomonas aeruginosa elastase.

A mutation, lasA1, that results in the synthesis of enzymatically inactive elastase protein was mapped by R68.45 plasmid-mediated conjugation and transposon-facilitated recombination to ca. 75 min on the Pseudomonas aeruginosa PAO chromosome. Since immunologically cross-reactive material is produced, the mutation presumably arose within the elastase structural gene.

The timing of child physical maltreatment: a cross-domain growth analysis of impact on adolescent externalizing and internalizing problems.

In a sample of 578 children assessed in kindergarten through the eighth grade, we used growth modeling to determine the basic developmental trajectories of mother-reported and teacher-reported externalizing and internalizing behaviors for three physical maltreatment groups of children-early-harmed (prior to age 5 years), later-harmed (age 5 years and over), and nonharmed--controlling for SES and gender. Results demonstrated that the earlier children experienced harsh physical treatment by significant adults, the more likely they were to experience adjustment problems in early adolescence. Over multiple domains, early physical maltreatment was related to more negative sequelae than the same type of maltreatment occurring at later periods. In addition, the fitted growth models revealed that the early-harmed group exhibited someswhat higher initial levels of teacher-reported externalizing problems in kindergarten and significantly different rates of change in these problem behaviors than other children, as reported by mothers over the 9 years of this study. The early-harmed children were also seen by teachers, in kindergarten, as exhibiting higher levels of internalizing behaviors. The later-harmed children were seen by their teachers as increasing their externalizing problem behaviors more rapidly over the 9 years than did the early- or nonharmed children. These findings indicate that the timing of maltreatment is a salient factor in examining the developmental effects of physical harm.