Differential effects of different antipsychotic drugs on cognitive function in patients with chronic schizophrenia.

BACKGROUND: Cognitive impairment is core feature of schizophrenia. The impact of antipsychotics on cognition remains controversial. This study aimed to examine the effects of long-term use of different types of antipsychotics on cognitive impairment in schizophrenia patients. METHODS: We used the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to assess the cognition of three groups of schizophrenia patients (318 on clozapine, 125 on risperidone, and 166 on typical antipsychotic drugs) and 399 healthy controls, and used the Positive and Negative Syndrome Scale to assess schizophrenia symptoms of patients. RESULTS: Patients taking typical antipsychotics scored higher on the immediate memory and delayed memory index than those taking clozapine or risperidone (all p < 0.01). Patients taking clozapine scored higher on the language subscale than those taking risperidone (p < 0.05). Multiple regression analysis showed that the drug type was identified as an independent contributor to the immediate memory, language, and delayed memory index of RBANS (all p < 0.05). CONCLUSIONS: Patients taking typical antipsychotics have better memory than those taking clozapine or risperidone. Patients taking clozapine have better language function than those taking risperidone.

Rhizobial peptidase HrrP cleaves host-encoded signaling peptides and mediates symbiotic compatibility.

Legume-rhizobium pairs are often observed that produce symbiotic root nodules but fail to fix nitrogen. Using the Sinorhizobium meliloti and Medicago truncatula symbiotic system, we previously described several naturally occurring accessory plasmids capable of disrupting the late stages of nodule development while enhancing bacterial proliferation within the nodule. We report here that host range restriction peptidase (hrrP), a gene found on one of these plasmids, is capable of conferring both these properties. hrrP encodes an M16A family metallopeptidase whose catalytic activity is required for these symbiotic effects. The ability of hrrP to suppress nitrogen fixation is conditioned upon the genotypes of both the host plant and the hrrP-expressing rhizobial strain, suggesting its involvement in symbiotic communication. Purified HrrP protein is capable of degrading a range of nodule-specific cysteine-rich (NCR) peptides encoded by M. truncatula. NCR peptides are crucial signals used by M. truncatula for inducing and maintaining rhizobial differentiation within nodules, as demonstrated in the accompanying article [Horváth B, et al. (2015) Proc Natl Acad Sci USA, 10.1073/pnas.1500777112]. The expression pattern of hrrP and its effects on rhizobial morphology are consistent with the NCR peptide cleavage model. This work points to a symbiotic dialogue involving a complex ensemble of host-derived signaling peptides and bacterial modifier enzymes capable of adjusting signal strength, sometimes with exploitative outcomes.