PBP2a in β-Lactam-Resistant Laboratory Mutants and Clinical Isolates: Disruption Versus Reduced Penicillin Affinity.

Alterations in PBP2a have been recognized in cefotaxime-resistant laboratory mutants and β-lactam-resistant clinical isolates of Streptococcus pneumoniae. DNA sequencing revealed fundamental differences between these two settings. Internal stop codons in pbp2a occurred in all three laboratory mutants analyzed, caused by a mutation in pbp2a of mutant C604, and tandem duplications within pbp2a resulting in premature stop codons in another two mutants C403 and C406.

Highly variable penicillin resistance determinants PBP 2x, PBP 2b, and PBP 1a in isolates of two Streptococcus pneumoniae clonal groups, Poland 23F-16 and Poland 6B-20.

Penicillin-binding proteins (PBPs) in representatives of two Streptococcus pneumoniae clonal groups that are prevalent in Poland, Poland 23F-16 and Poland 6B-20, were investigated by PBP profile analysis, antibody reactivity pattern analysis, and DNA sequence analysis of the transpeptidase (TP) domain-encoding regions of the pbp2x, pbp2b, and pbp1a genes. The isolates differed in their MICs of beta-lactam antibiotics. The majority of the 6B isolates were intermediately susceptible to penicillin (penicillin MICs, 0.

Sustained attention in children at risk for schizophrenia: findings with two visual continuous performance tests in a new sample.

In partial replication of an earlier study, 35 children at high risk for schizophrenia, 25 children at high risk for affective disorder, and 53 normal control children from a new sample of 7- to 12-year-old subjects were tested with two new visual continuous performance tests. Response levels and intrasubject variability were analyzed separately. Multivariate analyses on factor scores derived from response levels indicate that "groups" is a significant predictor for a factor reflecting discriminability (or sensitivity) for the more difficult of these tests but not for the less difficult one, and that high risk for schizophrenia is associated with lower performance.

Auditory recognition memory in adolescents at risk for schizophrenia: report on a verbal continuous recognition task.

As part of the New York High-Risk Project and in the context of a third round of testing, auditory short-term recognition memory for words and for consonant-vowel-consonant trigrams was measured in normal control adolescents (n = 53) and in adolescents at high risk for schizophrenia (n = 46). Differences in performance between the two groups are attributable to a lower initial memory strength on the part of the high-risk subjects, with trigrams showing larger differences than words. A subgroup of the high-risk subjects characterized by "clinical deviancy" showed, in addition, a (nonsignificant) increase in the rate of information loss from memory for trigrams.