Characterization of some of the enzymes in ragweed pollen.

Ragweed pollen contains 11 esterase, 5 acid phosphatase, 2 alkaline phosphatose, 2 hexokinase, 2 glucose-6-phosphate dehydrogenase isozymes and one leucine amino peptidase band which can be separated by starch gel electrophoresis. The isozymes were distinguished from one another by their electrophoretic mobility, heat inactivation temperatures and antigenic differences.     

Specific high-affinity binding of 125I-labeled mouse interferon to interfevon resistant embryonal carcinoma cells in vitro

Multipotential mouse embryonal carcinoma cells are resistant to several biologic effects of mouse interferon: inhibition of viral multiplication and inhibition of cell division. Nevertheless using ¹²⁵I-labeled highly purified mouse interferon we have shown that these embryonal carcinoma cells express specific interferon receptors in similar number and of the same affinity as interferon sensitive differentiated embryonal carcinoma cells. Thus, mechanisms of interferon resistance are probably multiple: some cells are resistant because they lack specific binding sites for interferon (interferon resistant mouse L1210 cells) and other cells, as shown herein, are resistant to some of the effects of interferon despite binding of interferon to specific receptor sites. Furthermore, these binding sites may be considered functional, since interferon does induce an increase in 2-5A synthetase in these cells.     

Substance use disorders in schizophrenia: review, integration, and a proposed model

Substance use disorders occur in approximately 40 to 50% of individuals with schizophrenia. Clinically, substance use disorders are associated with a variety of negative outcomes in schizophrenia, including incarceration, homelessness, violence, and suicide. An understanding of the reasons for such high rates of substance use disorders may yield insights into the treatment of this comorbidity in schizophrenia. This review summarizes methodological and conceptual issues concerning the study of substance use disorders in schizophrenia and provides a review of the prevalence of this co-occurrence. Prevailing theories regarding the co-occurrence of schizophrenia and substance use disorders are reviewed. Little empirical support is found for models suggesting that schizophrenic symptoms lead to substance use (self-medication), that substance use leads to schizophrenia, or that there is a genetic relationship between schizophrenia and substance use. An integrative affect-regulation model incorporating individual differences in traits and responses to stress is proposed for future study.     

Psychological treatment of benign headache disorders.

This article presents a selective summarization and critique of research on the psychological treatment of headache, with the primary focus on research appearing since 1980. Suggestions for future research directions and methodological improvements are included.     

Failure to produce conditioning with low-dose trimethylthiazoline or cat feces as unconditioned stimuli

Trimethylthiazoline (TMT), a derivative of fox feces, has been reported to fail to produce aversive conditioning as an unconditioned stimulus (UCS) when presented in large amounts (I. S. McGregor, L. Schrama, P. Ambermoon, & R. A. Dielenberg, 2002). Experiment I evaluated very low TMT levels that nonetheless produced defensive behaviors in rats during exposure. Although each level (0.01, 0.05, and 0.10 microl TMT) produced significant change in defensiveness, none resulted in significant changes the following day in the absence of TMT. Experiment 2 evaluated cat urine, cat feces, and cat fur/skin odor against a no-odor control. Urine produced no significant changes, but feces and fur/skin odors elicited virtually identical changes in defensive behaviors during exposure. When tested the next day in the absence of odor, the fur/skin odor-exposed group showed significant differences on the same behaviors as during exposure, but the feces-exposed group showed no differences on any measure. Results suggest that lack of conditioning to TMT may relate to the type of predator odor rather than the amount, predator species, or possible lack of odor components in TMT that are present in natural feces. Predator feces may also be less effective as a UCS because they are poorly predictive of the actual presence of the predator, suggesting the need for a reevaluation of UCS functions in aversive conditioning.     

Mosaic hexasomy 21.

Cases in which there are more than three copies of a sex chromosome, and rarely of an autosome, have been reported, but to our knowledge hexasomy has never been described except in tissue undergoing neoplastic change. This report describes a female infant with multiple malformations in whom we found a mosaic hexasomy 21. This was first detected in amniotic fluid cells and subsequently in skin fibroblasts.     

Kinetics and characterization of interferon production by murine spleen cells stimulated with Legionella pneumophila antigens.

Formalin-killed Legionella pneumophila bacterial cells, as well as a purified cell wall preparation (designated F-1 antigen) containing lipopolysaccharide (LPS), stimulated production of interferons (IFNs) in mouse spleen cell cultures. L. pneumophila whole-cell vaccine induced an IFN that was pH 2 labile and neutralized by anti-IFN-gamma indicating that IFN-gamma was the dominant form present. F-1 antigen induced a mixture of IFNs, depending upon the age of the culture and cell types present. In freshly prepared whole-spleen cultures and in 2-h adherent cultures, F-1 induced predominantly IFN-alpha/beta. In whole-spleen cultures that were allowed to age for 24 to 48 h before stimulation, F-1 was seen to induce mostly IFN-gamma, with low levels of IFN-alpha/beta present. Since only IFN-alpha/beta was produced in T-cell-depleted populations (at 2 h or at 48 h), it is suggested that T cells are responsible for IFN-gamma production in aged cultures. Additionally, heat-treated F-1, Escherichia coli LPS, and heat-treated E. coli LPS all induced similar levels of IFN-gamma in whole-splenocyte or nonadherent cell cultures which were incubated 48 h before stimulation. This suggests that LPS present in F-1 is responsible for IFN-gamma production and that an activated cell population is required. These results show that L. pneumophila antigens can induce the production of various types of IFN in mouse spleen cell cultures through several mechanisms.