P-selectin Expression Tracks Cerebral Atrophy in Mexican-Americans

Background and Purpose: We hypothesized that the P-selectin (SELP) gene, localized to a region on chromosome 1q24, pleiotropically contributes to increased blood pressure and cerebral atrophy. We tested this hypothesis by performing genetic correlation analyses for 13 mRNA gene expression measures from P-selectin and 11 other genes located in 1q24 region and three magnetic resonance imaging derived indices of cerebral integrity. Methods: The subject pool consisted of 369 (219F; aged 28–85, average = 47.1 ± 12.7 years) normally aging, community-dwelling members of large extended Mexican-American families. Genetic correlation analysis decomposed phenotypic correlation coefficients into genetic and environmental components among 13 leukocyte-based mRNA gene expressions and three whole-brain and regional measurements of cerebral integrity: cortical gray matter thickness, fractional anisotropy of cerebral white matter, and the volume of hyperintensive WM lesions. Results: From the 13 gene expressions, significant phenotypic correlations were only found for the P- and L-selectin expression levels. Increases in P-selectin expression levels tracked with decline in cerebral integrity while the opposite trend was observed for L-selectin expression. The correlations for the P-selectin expression were driven by shared genetic factors, while the correlations with L-selectin expression were due to shared environmental effects. Conclusion: This study demonstrated that P-selectin expression shared a significant variance with measurements of cerebral integrity and posits elevated P-selectin expression levels as a potential risk factor of hypertension-related cerebral atrophy.

Fractional anisotropy of cerebral white matter and thickness of cortical gray matter across the lifespan

We examined age trajectories of fractional anisotropy (FA) of cerebral white matter (WM) and thickness of cortical gray matter (GM) in 1031 healthy human subjects (aged 11-90 years). Whole-brain FA and GM thickness values followed quadratic trajectories with age but the relationship between them was linear, indicating that a putative biological mechanism may explain the non-linearity of their age trajectories. Inclusion of the FA values into the quadratic model of the whole-brain and regional GM thickness changes with age made the effect of the age(2) term no longer significant for the whole-brain GM thickness and greatly reduced its significance for regional GM thickness measurements. The phylogenetic order of cerebral myelination helped to further explain the intersubject variability in GM thickness. FA values for the early maturing WM were significantly better (p=10(-6)) at explaining variability in GM thickness in maturing (aged 11-20) subjects than FA values for the late maturing WM. The opposite trend was observed for aging subjects (aged 40-90) where FA values for the late maturing WM were better (p=10(-16)) at explaining the variability in GM thickness. We concluded that the non-linearity of the age trajectory for GM thickness, measured from T1-weighted MRI, was partially explained by the heterogeneity and the heterochronicity of the age-related changes in the microintegrity of cerebral WM. We consider these findings as the evidence that the measurements of age-related changes in GM thickness and FA are driven, in part, by a common biological mechanism, presumed to be related to changes in cerebral myelination.

Solution of an inverse problem for fractals and other sets

The problem of providing succinct approximate descriptions of given bounded subsets of R(n) can be solved by application of the contraction mapping principle.

Fractional anisotropy of water diffusion in cerebral white matter across the lifespan

Determining the time of peak of cerebral maturation is vital for our understanding of when cerebral maturation ceases and the cerebral degeneration in healthy aging begins. We carefully mapped changes in fractional anisotropy (FA) of water diffusion for eleven major cerebral white matter tracts in a large group (831) of healthy human subjects aged 11-90. FA is a neuroimaging index of micro-structural white matter integrity, sensitive to age-related changes in cerebral myelin levels, measured using diffusion tensor imaging. The average FA values of cerebral white matter (WM) reached peak at the age 32 ± 6 years. FA measurements for all but one major cortical white matter tract (cortico-spinal) reached peaks between 23 and 39 years of age. The maturation rates, prior to age-of-peak were significantly correlated (r=0.74; p=0.01) with the rates of decline, past age-of-peak. Regional analysis of corpus callosum (CC) showed that thinly-myelinated, densely packed fibers in the genu, that connect pre-frontal areas, maturated later and showed higher decline in aging than the more thickly myelinated motor and sensory areas in the body and splenium of CC. Our findings can be summarized as: associative, cerebral WM tracts that reach their peak FA values later in life also show progressively higher age-related decline than earlier maturing motor and sensory tracts. These findings carry multiple and diverse implications for both theoretical studies of the neurobiology of maturation and aging and for the clinical studies of neuropsychiatric disorders.

Processing speed is correlated with cerebral health markers in the frontal lobes as quantified by neuroimaging

We explored relationships between decline in cognitive processing speed (CPS) and change in frontal lobe MRI/MRS-based indices of cerebral integrity in 38 healthy adults (age 57-90 years). CPS was assessed using a battery of four timed neuropsychological tests: Grooved Pegboard, Coding, Symbol Digit Modalities Test and Category Fluency (Fruits and Furniture). The neuropsychological tests were factor analyzed to extract two components of CPS: psychomotor (PM) and psychophysical (PP). MRI-based indices of cerebral integrity included three cortical measurements per hemisphere (GM thickness, intergyral and sulcal spans) and two subcortical indices (fractional anisotropy (FA), measured using track-based spatial statistics (TBSS), and the volume of hyperintense WM (HWM)). MRS indices included levels of choline-containing compounds (GPC+PC), phosphocreatine plus creatine (PCr+Cr), and N-acetylaspartate (NAA), measured bilaterally in the frontal WM bundles. A substantial fraction of the variance in the PM-CPS (58%) was attributed to atrophic changes in frontal WM, observed as increases in sulcal span, declines in FA values and reductions in concentrations of NAA and choline-containing compounds. A smaller proportion (20%) of variance in the PP-CPS could be explained by bilateral increases in frontal sulcal span and increases in HWM volumes.

National survey of physicians practice patterns: Fertility preservation and cancer patients

CRA9508

Background: Addressing the impact of cancer treatment on fertility is a high priority in providing quality cancer care to patients of childbearing age. Evidence suggests less than 50% of patients receive adequate fertility information prior to cancer treatment. This study assessed the practice patterns of physicians and identified perceptions of barriers to communication about fertility. Methods: A 37 item survey was developed by a review of the literature and previous qualitative interviews. A random sample of physicians from the American Medical Association Masterfile was stratified by board specialty related to oncology. Three waves of surveys were distributed across the United States. The domains of the survey included demographics, knowledge, attitudes and practice behaviors related to FP with patients of childbearing age. Results: Of 1,979 physicians identified, a total of 613 physicians completed the survey, yielding a 33% response rate among oncologists. Oncologists with favorable attitudes towards FP were 4.9 times more likely to discuss the impact of cancer treatment on future fertility than those who have unfavorable attitudes. GYN or Medical/Hematological oncologists were 2.1 times more likely than other specialists to report feeling comfortable discussing FP with their patients. The majority of oncologists reported discussing FP with patients and indicated the primary barrier to discussion was a patient too ill to delay treatment. However, less than 25% of oncologists report referring patients for FP and only 38% report knowledge of the ASCO guidelines suggesting oncologists should discuss FP and refer all patients of childbearing age. Less than 25% of physicians surveyed reported distributing educational materials regarding FP. Conclusions: The majority of physicians in this survey report discussing FP; however they are not consulting specialists or providing educational materials to their patients. Future research will include the development of physician and nurse training curricula and interventions to facilitate discussion of FP between physicians and cancer patients.

No significant financial relationships to disclose.

National survey of physicians practice patterns: Fertility preservation and cancer patients

CRA9508

The full, final text of this abstract will be available in Part II of the 2009 ASCO Annual Meeting Proceedings, distributed onsite at the Meeting on May 30, 2009, and as a supplement to the June 20, 2009, issue of the Journal of Clinical Oncology.

No significant financial relationships to disclose.

Absence of Pneumocystis jiroveci pneumonia in liver transplantation recipients receiving short-term (3-month) prophylaxis

Pneumocystis jiroveci (formerly known as Pneumocystis carinii) is a fungal pathogen that causes pneumonia (PCP) in liver transplant recipients. Consequently, prophylaxis with trimethoprim-sulfamethoxazole (TMP/SMZ) is typically administered for at least 1 year at most liver transplant programs. At our center we have utilized a short-term (3-month) prophylactic regimen with TMP/SMZ for the past decade and report our experience and speculate on the potential widespread application of this approach.

METHODS

For patients transplanted at our center between January 1997 and January 2007, we recorded all documented PCP infections by review of our liver transplant database and hospital-based electronic medical records system, both of which record all infections and culture results.

RESULTS

We recorded no cases of PCP in any of the liver transplant recipients at our center during the study period.

CONCLUSIONS

We report the absence of PCP in a large cohort of liver transplant recipients receiving a short-term (3-month) prophylaxis with TMP/SMZ. These findings provide a rational basis to consider short-term (3-month) PCP prophylaxis or avoidance of prophylaxis altogether in selected low-risk patients.