A critical review of chronic stress effects on spatial learning and memory

The purpose of this review is to evaluate the effects of chronic stress on hippocampal-dependent function, based primarily upon studies using young, adult male rodents and spatial navigation tasks. Despite this restriction, variability amongst the findings was evident and how or even whether chronic stress influenced spatial ability depended upon the type of task, the dependent variable measured and how the task was implemented, the type and duration of the stressors, housing conditions of the animals that include accessibility to food and cage mates, and duration from the end of the stress to the start of behavioral assessment. Nonetheless, patterns emerged as follows: For spatial memory, chronic stress impairs spatial reference memory and has transient effects on spatial working memory. For spatial learning, however, chronic stress effects appear to be task-specific: chronic stress impairs spatial learning on appetitively motivated tasks, such as the radial arm maze or holeboard, tasks that evoke relatively mild to low arousal components from fear. But under testing conditions that evoke moderate to strong arousal components from fear, such as during radial arm water maze testing, chronic stress appears to have minimal impairing effects or may even facilitate spatial learning. Chronic stress clearly impacts nearly every brain region and thus, how chronic stress alters hippocampal spatial ability likely depends upon the engagement of other brain structures during behavioral training and testing.     

Receptor–receptor interactions: A novel concept in brain integration

A brief historical presentation of the hypothesis on receptor–receptor interactions as an important integrative mechanism taking place at plasma membrane level is given. Some concepts derived from this integrative mechanism especially the possible assemblage of receptors in receptor mosaics (high-order receptor oligomers) and their relevance for the molecular networks associated with the plasma membrane are discussed. In particular, the Rodbell's disaggregation theory for G-proteins is revisited in the frame of receptor mosaic model.     

Increased consumption of dietary cholesterol,lutein, and zeaxanthin as egg yolks does not decrease serum concentrations and lipoprotein distribution of other carotenoids,retinol, and tocopherols

We have previously reported that consumption of lutein and zeaxanthin as 2 and 4 egg yolks per day for 5 weeks significantly increased serum lutein and zeaxanthin concentrations in older adults taking cholesterol-lowering statins. We hypothesized that increased consumption of eggs, lutein, and zeaxanthin may correlate with decreased absorption of other carotenoids and increased absorption of vitamins A and E, thus affecting their serum concentrations and lipoprotein distribution. Fifty-two subjects aged at least 60 years consumed 2 egg yolks per day followed by 4 egg yolks per day for 5 weeks each with a 4-week egg-free period at baseline and between the 2 interventions. Mean serum β-cryptoxanthin, lycopene, α-carotene, β-carotene, α-tocopherol, and retinol concentrations did not change during the 2 and 4 egg yolk phases. Mean serum α-cryptoxanthin and γ-tocopherol concentrations did not change after the 2 egg yolk phase, but increased by 47% (P < .001) and 19% (P < .05), respectively, after the 4 egg yolk phase. The percentage distribution of carotenoids and tocopherols between the high-density lipoprotein (HDL) and non-HDL fractions was not significantly different during the egg yolk phases compared with baseline despite the significant increases in lutein and zeaxanthin carried on HDL and non-HDL fractions. In conclusion, increased dietary cholesterol, lutein, and zeaxanthin consumed as egg yolks did not decrease the absorption of other carotenoids, and increased γ-tocopherol but not retinol as evidenced by their serum and lipoprotein concentrations. Two and 4 egg yolk consumption increases serum and retinal lutein and zeaxanthin without altering the serum status of the other carotenoids, tocopherol, and retinol.     

Glucosamine attenuates increases of intraabdominal fat,serum leptin levels,and insulin resistance induced by a high-fat diet in rats

The levels of circulating nonesterified fatty acids increase during obesity and contribute to insulin resistance by inhibiting insulin-stimulated glucose transport and phosphorylation in human muscles. In cells, glucose-6-phosphate is primarily used in glycogenesis and glycolysis; only 1% to 3% is converted to glucosamine-6-phosphate, which enters the hexosamine-biosynthesis pathway. The major end product of this pathway, uridine-5′-diphosphate-N-acetyl-glucosamine, which is increased by exogenous glucosamine (GlcN) administration, mediates insulin resistance. We hypothesized that the administration of GlcN to rats receiving a high-fat (HF) diet may potentiate the effects of an HF diet on glucose tolerance and other metabolic variables. To evaluate this relationship, 2 groups of rats were fed with a control or HF diet; and another 2 groups received glucosamine hydrochloride at a dose of 500 mg/kg dissolved in drinking water for 21 weeks. Metabolic variables related to insulin resistance were then measured. The levels of blood glucose and serum insulin were higher in a glucose tolerance test in the HF group as compared with the control group. Rats receiving GlcN had reduced liver glycogen and only slightly worsened glucose tolerance as compared with control rats, although this did not induce insulin resistance as evaluated by the homeostasis model assessment. Glucosamine administration was able to partially or completely inhibit some effects of the HF diet by reducing fat depot weight and serum leptin levels, thus resulting in a smaller increase in the insulinemic response to a glucose injection and lower postabsorptive glycemia.     

What does individual strength say about resistance training status?

The point at which an individual becomes resistance “trained” is not well defined in the literature. Some studies have defined training status as having engaged in consistent resistance training activities for a given period of time, whereas others base inclusion criteria on strength levels alone, or levels of strength in combination with training age/time. If the primary focus of a study is to examine adaptations in individuals with high levels of strength, then it may be appropriate to exclude the individuals who do not meet strength requirements. However, given the heterogeneity of the strength response to resistance training, strength cannot separate those who are “trained” from those who are “untrained.” We suggest that, when determining resistance training status, training age (time) and the modality of training (specificity) should be the primary criteria considered. Muscle Nerve 55 : 455–457, 2017     

Haptoglobin-beta chain defined by monoclonal antibody RM2 as a novel serum marker for prostate cancer

In our previous study, monoclonal antibody RM2, established toward the glycosyl epitope, reflected grade of malignancy of prostate cancer cells whereas RM2 reactivity to benign glands was negative or weak. RM2 reactivity was also detected in stroma, suggesting the glycoprotein RM2 recognizes could be released into the bloodstream. Then, we explored RM2 reactivity to sera of early prostate cancer. We compared RM2 reactivity to sera between 62 patients with early prostate cancer and 43 subjects with benign prostatic disease, and examined RM2 reactivity before and after radical prostatectomy in 15 patients by Western blotting. We also examined RM2 reactivity to sera of the other urogenital cancers. RM2 reactivity was significantly enhanced on a serum glycoprotein with molecular mass approximately 40 kDa, hereby termed GPX, in the patients with early prostate cancer when compared with those with benign prostatic disease (p < 0.0001). Setting an appropriate cutoff level, RM2 reactivity to GPX for detection of prostate cancer had sensitivity of 87% and specificity of 84%, respectively. Furthermore, the level of RM2 reactivity significantly decreased after radical prostatectomy (p = 0.006). However, increased RM2 reactivity to GPX was also observed in the other urogenital cancers. The proteomics approach identified GPX as haptoglobin-beta chain and RM2 showed preferential reactivity toward haptoglobin-beta chain derived from prostate cancer when compared with polyclonal anti-haptoglobin antibody. Haptoglobin-beta chain defined by RM2 is a novel serum marker that may be useful for detection of early prostate cancer when coupled with prostate-specific antigen because it is not specific to prostate cancer.     

药源性横纹肌溶解综合征回顾性分析

目的：了解药物所致横纹肌溶解综合征（RM）的发生情况及临床特点,提高防治水平。方法：收集与分析中国生物医学文献数据库及中国医院数字图书馆期刊全文库（1994年1月～2009年8月）药物所致RM的病例。结果：药物所致RM159例,口服给药比其他给药途径更易引起RM,有131人占总数的82.39%。发生于用药2个月内RM的有48例,占54.55%。常见药物有26种,按发生例数排序前4位的药物有：调节血脂药58例（占36.48%）排在首位,其中他汀类调节血脂药有49例。其次是乙醇32例（占20.13%）、有机磷农药30例（占18.87%）、阿片类药其中海洛因15例（占9.43%）。结论：许多常用药物均可引起RM,使其发病率日益增多,若不及时诊断,治疗常可威胁生命。     

Improving discrimination capacity through rapidly mutating Y-STRs in structured populations from the African continent

Y chromosome short tandem repeats (Y-STRs) typing is becoming increasingly popular in forensic casework mainly because it allows the recovery of male-specific genetic information from severely unbalanced male-female DNA mixtures. The relatively low discrimination power of conventional Y-STR multiplexes, due to linkage disequilibrium among polymorphic loci, has been partially overcome by the introduction of rapidly mutating Y microsatellites (RM Y-STRs) with mutation rates exceeding 1 × 10^-2/generation. In previous works, we reported an unexpectedly high level of haplotype sharing among African males using the Yfiler Plus PCR Amplification kit, the most powerful commercially available system, including 19 conventional Y-STRs and 6 RM Y-STRs. In particular, analyzing 1370 males from northern, eastern and central Africa, 240 subjects were found to share 100 Y-STR haplotypes. We attributed the relatively low discrimination capacity to several factors including patrilocality, endogamy, sampling bias and degree of urbanization. In the present study, using a blind search analysis based on 16 autosomal STRs, we first investigated the kinship between pairs of African males previously found to share the Yfiler Plus haplotype; then, we evaluated the improvement in identification capacity allowed by a PCR multiplex assay (RM-YPlex) based on 13 “first generation” RM Y-STR, seven of which are not included in the Yfiler Plus multiplex. Among 228 pairs of males sharing a Yfiler Plus haplotype, we detected 134 related (cousins or closer) and 94 unrelated (or distantly related) pairs of subjects. By using the RM-YPlex, we observed a full genotype concordance for the six loci shared with the Yfiler Plus, while the additional seven RM Y-STRs allowed the discrimination among 58.2 % related pairs and 84.0 % unrelated pairs. The discrimination capacity increased from 0.898 to 0.958, while the proportion of males sharing a haplotype decreased from 17.5 % to 8.0 %. These findings further highlight the capability of RM Y-STRs to distinguish males even in close kinship scenarios and in sub-structured populations as African ones, but at the same time call for the discovery and testing of additional RM Y-STRs to fully differentiate male relatives.