An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis

Based on elevated concentrations of a set of “impact markers” at the onset of the Younger Dryas stadial from sedimentary contexts across North America, Firestone, Kennett, West, and others have argued that 12.9 ka the Earth experienced an impact by an extraterrestrial body, an event that had devastating ecological consequences for humans, plants, and animals in the New World [Firestone RB, et al. (2007) Proc. Natl. Acad. Sci. USA 104:16016–16021]. Herein, we report the results of an independent analysis of magnetic minerals and microspherules from seven sites of similar age, including two examined by Firestone et al. We were unable to reproduce any results of the Firestone et al. study and find no support for Younger Dryas extraterrestrial impact.     

Methodological considerations for aging research: Introduction to a symposium and methodological commentary

This article introduces a set of papers which illustrate the application or multivariate techniques to problems in aging research. Multivariate research strategies raise new issues in the choice of sample size that are discussed. The papers reviewed in this introduction are concerned with factorial invariance, the measurement of change, and various regression techniques useful in modeling developmental data.     

Relationship of clinical symptoms and substance use in schizophrenia patients on conventional versus atypical antipsychotics

A large body of research documents the high prevalence and devastating consequences of substance abuse among individuals diagnosed with schizophrenia. One prominent theory of the high rate of comorbidity between these disorders is that substance abuse in schizophrenia is an attempt to self-medicate psychiatric symptoms including negative symptoms and depression as well as side effects including extrapyramidal reactions (EPR). Consistent with this notion, novel antipsychotic medications, which have been shown to reduce negative and depressive symptoms while exhibiting a lower propensity to cause EPR, have been associated with reduced substance abuse in patients with schizophrenia. To further explore the self-medication hypothesis as it relates to the mechanism by which atypical antipsychotics reduce substance abuse, we compared schizophrenia patients with a history of substance abuse medicated with either conventional (n = 35) or atypical (n = 35) antipsychotics. Patients with schizophrenia who did not have a history of substance abuse who were on conventional (n = 23) vs. atypical antipsychotics (n = 29) were also examined. Assessments included the Positive and Negative Symptom Scale, Hamilton Rating Scale for Depression, Simpson-Angus, and Abnormal Involuntary Movement Scale. Compared with conventional medications, atypical antipsychotic drugs were associated with reduced levels of substance use (primarily alcohol). Interestingly, however, in substance-abusing patients there were no significant differences between patients on conventional vs. atypical agents with respect to positive or negative symptoms, depression, or EPR. These data suggest that theories related to self-medication of symptoms and side effects do not appear to account for the difference in rates of substance use found in schizophrenia patients on atypical vs. conventional antipsychotic medications.     

Sweet syndrome in multiple myeloma: a series of six cases

BACKGROUND: Sweet syndrome (SS), a paraneoplastic syndrome characterized by fever, neutrophilia, multiple erythematous painful plaques, and a dense dermal neutrophilic infiltration, has a known association with hematologic malignancies such as acute myelogenous leukemia. However, no clear association with multiple myeloma (MM) has been reported. MATERIALS AND METHODS: Pathology reports of the 2357 patients with multiple myeloma at the University of Arkansas for Medical Sciences were reviewed to retrieve cases who had developed SS. Cytogenetic studies and immunoglobulin secretory status were retrieved. Five cases of SS in MM and 25 cases of SS in patients without MM underwent syndecan-1 immunohistochemistry. OBSERVATIONS: Six cases of SS occurring in the setting of MM showed a predominance in patients secreting IgG paraprotein. Five of the six patients received granulocyte-colony stimulating factor while the sixth received granulocyte-monocyte-colony stimulating factor. Fifty percent showed a non-specific cytogenetic anomaly. CONCLUSIONS: There is no specific cytogenetic anomaly associated with SS in the setting of MM. This paraneoplastic syndrome may be secondary to elevated levels of granulocyte colony stimulating factor (G-CSF), possibly with a component of enhanced sensitivity to endogenous G-CSF. The immunoglobulin secretory status parallels that seen in MM with cutaneous involvement, but IgG secretors may be at an increased risk of developing SS compared with their counterparts who secrete other immunoglobulins.     

Induction of a brainstem correlate of conditioned taste aversion expression: role of the pontine parabrachial nucleus

Increases in Fos-like immunoreactivity (FLI) in the intermediate division of the nucleus of the solitary tract (iNTS) are seen following the expression of a conditioned taste aversion (CTA). In studies limited to behavioral assessment, the pontine parabrachial nucleus (PBN) has been demonstrated to play a critical role in the acquisition, but not the expression, of CTAs. To better define the role of the PBN in taste aversion learning, the present study examined the effects of PBN lesions on FLI in iNTS in animals with lesions placed either before or after CTA training. As is the case with behavioral expression of a CTA, timing of PBN lesions was found to be critical. Lesions placed prior to conditioning blocked evidence of conditioning, including both taste rejection and FLI in iNTS. Lesions placed after conditioning, but before testing, did not interfere with either taste rejection or FLI. These results support and extend prior claims that PBN is critical for CTA acquisition but not expression. They also demonstrate that input from PBN to iNTS is not necessary for the FLI seen there during CTA expression.