Appraisal, coping, and social support as mediators of well-being in Black and White family caregivers of patients with Alzheimer's disease.

Family caregivers of patients with Alzheimer's disease (AD) commonly have high levels of psychological distress. Black caregivers often report less depression than White caregivers, but the process underlying this difference is poorly understood. With the use of a stress process model, 123 White and 74 Black family caregivers of patients with AD and other progressive dementias were studied. Black caregivers appraised patient problems as less stressful and reported higher self-efficacy in managing caregiving problems and less depression than did White caregivers. White and Black caregivers also differed significantly in coping responses but not in social supports. Structural equation analyses indicated that the correlational structure of the stress process was similar in White and Black caregivers. Caregiving stressors and race did not affect well-being through direct paths, but they were mediated by effects for appraisal, social support and activity, and coping. Possible cultural mechanisms explaining the better adjustment among Black caregivers are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abrogation of the G2 cell cycle checkpoint associated with overexpression of HSIX1: a possible mechanism of breast carcinogenesis

While conducting a search for cell cycle-regulated genes in human mammary carcinoma cells, we identified HSIX1, a recently discovered member of a new homeobox gene subfamily. HSIX1 expression was absent at the onset of and increased toward the end of S phase. Since its expression pattern is suggestive of a role after S phase, we investigated the effect of HSIX1 in the G2 cell cycle checkpoint. Overexpression of HSIX1 in MCF7 cells abrogated the G2 cell cycle checkpoint in response to x-ray irradiation. HSIX1 expression was absent or very low in normal mammary tissue, but was high in 44% of primary breast cancers and 90% of metastatic lesions. In addition, HSIX1 was expressed in a variety of cancer cell lines, suggesting an important function in multiple tumor types. These data support the role for homeobox genes in tumorigenesis/tumor progression, possibly through a cell cycle function.     

Infectious causes of atherosclerosis

Brain imaging studies have suggested a critical role for prefrontal cortex in working memory (WM) tasks that require both maintainenance and manipulation of information over time in delayed-response WM tasks. In the present study, functional magnetic resonance imaging (fMRI) was used to examine whether prefrontal areas are activated when only maintenance is required in a delayed-response WM task, without the overt requirement to manipulate the stored information. In two scans, six subjects performed WM tasks in which, on each trial, they (1) encoded 1, 3, or 6 to-be-remembered letters, (2) maintained these letters across a 5-second unfilled delay, and (3) determined whether a single probe letter was or was not part of the memory set. Activation of left caudal inferior frontal gyrus was observed, relative to the 1-letter task, when subjects were required to maintain 3 letters in WM. When subjects were required to maintain 6 letters in WM, additional prefrontal areas, most notably middle and superior frontal gyri, were activated bilaterally. Thus, increasing the amount of to-be-maintained information, without any overt manipulation requirement, resulted in the recruitment of wide-spread frontal-lobe regions. Inferior frontal gyrus activation was left-hemisphere dominant in both the 3- and 6-letter conditions, suggesting that such activation reflected material-specific verbal processes. Activation in middle and superior frontal gyri appeared only in the 6-letter condition and was right-hemisphere dominant, suggesting that such activation reflected material-independent executive processes.     

Characterization of leptospiral catalase and peroxidase

Peroxidase from Leptospira biflexa strain B-16 ad catalase from Leptospira interrogans canicola Hond Utrecht were characterized and compared and both appeared to be heme enzymes as judged by their inhibition profiles and rapid inactivation during catalysis. Neither enzyme exhibited monovalent or divalent cation requirements. Dialysis of cell-free extracts resulted in loss of peroxidase activity but catalase was unaffected by this procedure. Peroxidase had a Km for H2O2 of 12.5 microM while catalase had a Km of 70 mM for H2O2. Catalase and peroxidase were physically separated by sedimentation in linear sucrose gradients. The specific activities of each enzyme seemed to be a function of the state of growth at which the cells were harvested and both enzymes were found associated with membranes, peroxidase by hydrophobic and catalase by ionic interactions. Speculative deductions are presented concerning the phylogenetic interrelationships of both enzymes as well as their significance in the biology and pathogenicity of leptospires.     

A One and a Half Centered Expansion for Ion Atom Collisions

A new method for numerically calculating ion atom collisions is presented. It uses time dependent amplitudes for target excitation and ionization but time independent amplitudes for charge transfer. It is efficient in its use of computer time and removes the known difficulty with a single centered expansion for the proton hydrogen system below 60 keV.