Factor analysis of the Communication Disturbances Index

The present study utilized factor analysis to investigate possible underlying processes in schizophrenic thought disorder. Using the Communication Disturbances Index [CDI; Arch. Gen. Psychiatry, 53, (1996) 358], a measure of disruption in the communication of meaning from speaker to listener, we examined the speech of 58 stable schizophrenia outpatients for six different types of referential communication disturbances. We calculated instances of disturbance per 100 words and then factor-analyzed our data using the SAS statistical package. Principal components analysis with an oblique rotation produced both a two- and a three-factor solution, depending on factor inclusion criteria. In the three-factor solution, the first two factors reflected weaknesses in language structural organization and in concept-boundary definition, respectively. The third factor appeared to reflect weaknesses in specific facets of memory functioning. In the two-factor solution, the aforementioned structural organization and concept-boundary definition factors were combined into a single executive functioning factor. Results from the study may be heuristic in the development of models of language disturbance in schizophrenia patients.     

Phosphorylation-dependent nucleocytoplasmic shuttling of pancreatic duodenal homeobox-1

Pancreatic duodenal homeobox-1 (PDX-1) is a homeodomain protein that plays an important role in the development of the pancreas and in maintaining the identity and function of the islets of Langerhans. It also regulates the expression of the insulin gene in response to changes in glucose and insulin concentrations. Glucose and insulin regulate PDX-1 by way of a signaling pathway involving phosphatidylinositol 3-kinase (PI 3-kinase) and SAPK2/p38. Activation of this pathway leads to phosphorylation of PDX-1 and its movement into the nucleus. To investigate the intracellular trafficking of PDX-1, immunocytochemistry was used to localize PDX-1 in the human beta-cell line NesPDX-1, in which PDX-1 is overexpressed, and in MIN6 beta-cells. In low-glucose conditions, PDX-1 localized predominantly to the nuclear periphery, with some staining in the cytoplasm. After stimulation with glucose, PDX-1 was present in the nucleoplasm. The translocation of PDX-1 to the nucleoplasm was complete within 15 min and occurred in 5-10 mmol/l glucose. Insulin and sodium arsenite, an activator of the stress-activated pathway, also stimulated PDX-1 movement from the nuclear periphery to the nucleoplasm. When cells were transferred between high glucose- and low glucose-containing medium, PDX-1 rapidly shuttled between the nuclear periphery and the nucleoplasm. Glucose- and insulin-stimulated translocation of PDX-1 to the nucleoplasm was inhibited by wortmannin and SB 203580, indicating that a pathway involving PI 3-kinase and SAPK2/p38 was involved; translocation was unaffected by PD 098959 and rapamycin, suggesting that neither mitogen-activated protein kinase nor p70(s6k) were involved. Arsenite-stimulated import of PDX-1 into the nucleus was inhibited by SB 203580 but not by wortmannin. Export from the nucleoplasm to the nuclear periphery was inhibited by calyculin A and okadaic acid, suggesting that dephosphorylation of PDX-1 was involved. These results demonstrated that PDX-1 shuttles between the nuclear periphery and nucleoplasm in response to changes in glucose and insulin concentrations and that these events are dependent on PI 3-kinase, SAPK2/p38, and a nuclear phosphatase(s).     

Mixing patterns and the spread of close-contact infectious diseases

Surprisingly little is known regarding the human mixing patterns relevant to the spread of close-contact infections, such as measles, influenza and meningococcal disease. This study aims to estimate the number of partnerships that individuals make, their stability and the degree to which mixing is assortative with respect to age. We defined four levels of putative at-risk events from casual (physical contact without conversation) to intimate (contact of a sexual nature), and asked university student volunteers to record details on those they contacted at these levels on three separate days. We found that intimate contacts are stable over short time periods whereas there was no evidence of repeat casual contacts with the same individuals. The contacts were increasingly assortative as intimacy increased. Such information will aid the development and parameterisation of models of close contact diseases, and may have direct use in outbreak investigations.