Drug delivery systems for cancer chemotherapy are employed to improve the effectiveness and decrease the side-effects of highly toxic drugs. Most chemotherapy agents have indiscriminate cytotoxicity that affects normal, as well as cancer cells. To overcome these problems, new more efficient nanosystems for drug delivery are increasingly being investigated. Polyamidoamine (PAMAM) dendrimers are an example of a versatile and reproducible type of nanocarrier that can be loaded with drugs, and modified by attaching target-specific ligands that recognize receptors that are over-expressed on cancer cells. PAMAM dendrimers with a high density of cationic charges display electrostatic interactions with nucleic acids (DNA, siRNA, miRNA, etc.), creating dendriplexes that can preserve the nucleic acids from degradation. Dendrimers are prepared by conducting several successive “generations” of synthetic reactions so their size can be easily controlled and they have good uniformity. Dendrimers are particularly well-suited to co-delivery applications (simultaneous delivery of drugs and/or genes). In the current review, we discuss dendrimer-based targeted delivery of drugs/genes and co-delivery systems mainly for cancer therapy.

Background Three versions of Perceived Stress Scale (PSS-14, PSS-10, and PSS-4) are among the most widely used measures of stress. The aim of current study was to validate this instrument in a sample of non-demented elderly adults to facilitate studies of the impact of stress on health. Methods 768 nondemented adults over the age of 70 years completed the PSS-14 questionnaire and other neuropsychological tests. Exploratory Factor Analysis (EFA) was used to determine the underlying factor structure of all PSS versions and Confirmatory Factor Analysis (CFA) was used to test the construct validity of factors. The internal consistency reliability of the scales was assessed using Cronbach's alpha, and concurrent validity was evaluated by examining PSS relation with age, gender, depression, anxiety, and Positive Affect and Negative Affect Schedule (PANAS). Results A two-factor model was the optimal fit for the 14- and 10-item versions of PSS. For the PSS-14, all items’ loadings exceeded 0.4 for one of the two factors except item 12. Therefore, we studied a 13-item version of PSS as well as 10- and 4-item subsets representing PSS-10 and PSS-4. Internal consistency coefficients were satisfactory for the full scale of PSS-13 and PSS-10, but not for PSS-4. Women reported higher levels of stress than men. Higher levels of total PSS scores showed association with higher levels of depression, anxiety, and negative affect, and lower level of positive affect. Conclusions The 13- and 10-item versions of PSS may be used to understand the experience of stress among older adults.

The hippocampus plays a critical role in verbal and spatial memory, thus any pathological damage to this formation may lead to cognitive impairment. It is suggested that right and left hippocampi are affected differentially in healthy or pathologic aging. The purpose of this study was to test the hypothesis that verbal episodic memory performance is associated with left hippocampal volume (HV) while spatial memory is associated with right HV. 115 non-demented adults over age 70 were drawn from the Einstein Aging Study. Verbal memory was measured using the free recall score from the Free and Cued Selective Reminding Test – immediate recall (FCSRT-IR), logical memory immediate and delayed subtests (LM-I and LM-II) from the Wechsler Memory Scale-Revised (WMS-R). Spatial Memory was measured using a computerized dot memory paradigm that has been validated for use in older adults. All participants underwent 3T MRI with subsequent automatized measurement of the volume of each hippocampus. The sample had a mean age of 78.7 years (SD=5.0); 57% were women, and 52% were white. Participants had a mean of 14.3 years (SD=3.5) of education. In regression models, two tests of verbal memory (FCSRT-IR free recall and LM-II) were positively associated with left HV, but not with right HV. Performance on the spatial memory task was associated with right HV, but not left HV. Our findings support the hypothesis that the left hippocampus plays a critical role in episodic verbal memory, while right hippocampus might be more important for spatial memory processing among non-demented older adults.

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Introduction: Selective hippocampal (HC) subfield atrophy has been reported in older adults with mild cognitive impairment and Alzheimer’s disease. The goal of this study was to investigate the associations between the volume of hippocampal subfields and visual and verbal episodic memory in cognitively normal older adults. Methods: This study was conducted on a subset of 133 participants from the Einstein Aging Study (EAS), a community-based study of non-demented older adults systematically recruited from the Bronx, N.Y. All participants completed comprehensive EAS neuropsychological assessment. Visual episodic memory was assessed using the Complex Figure Delayed Recall subtest from the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Verbal episodic memory was assessed using Delayed Recall from the Free and Cued Selective Reminding Test (FCSRT). All participants underwent 3T MRI brain scanning with subsequent automatic measurement of the hemispheric hippocampal subfield volumes (CA1, CA2- CA3, CA4-dente gyrus, presubiculum, and subiculum).Weused linear regressions to model the association between hippocampal subfield volumes and visual and verbal episodic memory tests while adjusting for age, sex, education, and total intracranial volume. Results: Participants had a mean age of 78.9 (SD = 5.1) and 60.2% were female. Total hippocampal volume was associated with Complex Figure Delayed Recall (β = 0.31, p = 0.001) and FCSRT Delayed Recall (β = 0.27, p = 0.007); subiculum volume was associated with Complex Figure Delayed Recall (β = 0.27, p = 0.002)and FCSRT Delayed Recall ( β = 0.24, p = 0.010); CA1 was associated with Complex Figure Delayed Recall ( β = 0.26, p < 0.002) and FCSRT Delayed Recall ( β = 0.20, p = 0.025). Conclusions: Our findings confirm previous research on the specific roles of CA1 and subiculum in episodic memory. Our results suggest that hippocampal subfields have sensitive roles in the process of visual and verbal episodic memory.

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