The Intersection of cerebral cholesterol metabolism and Alzheimer's disease: Mechanisms and therapeutic prospects.

Alzheimer's disease (AD) is a common neurodegenerative disease in the elderly, the exact pathogenesis of which remains incompletely understood, and effective preventive and therapeutic drugs are currently lacking. Cholesterol plays a vital role in cell membrane formation and neurotransmitter synthesis, and its abnormal metabolism is associated with the onset of AD. With the continuous advancement of imaging techniques and molecular biology methods, researchers can more accurately explore the relationship between cholesterol metabolism and AD. Elevated cholesterol levels may lead to vascular dysfunction, thereby affecting neuronal function. Additionally, abnormal cholesterol metabolism may affect the metabolism of ß-amyloid protein, thereby promoting the onset of AD. Brain cholesterol levels are regulated by multiple factors. This review aims to deepen the understanding of the subtle relationship between cholesterol homeostasis and AD, and to introduce the latest advances in cholesterol-regulating AD treatment strategies, thereby inspiring readers to contemplate deeply on this complex relationship. Although there are still many unresolved important issues regarding the risk of brain cholesterol and AD, and some studies may have opposite conclusions, further research is needed to enrich our understanding. However, these findings are expected to deepen our understanding of the pathogenesis of AD and provide important insights for the future development of AD treatment strategies targeting brain cholesterol homeostasis.

The role of mitochondria in myocardial damage caused by energy metabolism disorders: From mechanisms to therapeutics.

Myocardial damage is the most serious pathological consequence of cardiovascular diseases and an important reason for their high mortality. In recent years, because of the high prevalence of systemic energy metabolism disorders (e.g., obesity, diabetes mellitus, and metabolic syndrome), complications of myocardial damage caused by these disorders have attracted widespread attention. Energy metabolism disorders are independent of traditional injury-related risk factors, such as ischemia, hypoxia, trauma, and infection. An imbalance of myocardial metabolic flexibility and myocardial energy depletion are usually the initial changes of myocardial injury caused by energy metabolism disorders, and abnormal morphology and functional destruction of the mitochondria are their important features. Specifically, mitochondria are the centers of energy metabolism, and recent evidence has shown that decreased mitochondrial function, caused by an imbalance in mitochondrial quality control, may play a key role in myocardial injury caused by energy metabolism disorders. Under chronic energy stress, mitochondria undergo pathological fission, while mitophagy, mitochondrial fusion, and biogenesis are inhibited, and mitochondrial protein balance and transfer are disturbed, resulting in the accumulation of nonfunctional and damaged mitochondria. Consequently, damaged mitochondria lead to myocardial energy depletion and the accumulation of large amounts of reactive oxygen species, further aggravating the imbalance in mitochondrial quality control and forming a vicious cycle. In addition, impaired mitochondria coordinate calcium homeostasis imbalance, and epigenetic alterations participate in the pathogenesis of myocardial damage. These pathological changes induce rapid progression of myocardial damage, eventually leading to heart failure or sudden cardiac death. To intervene more specifically in the myocardial damage caused by metabolic disorders, we need to understand the specific role of mitochondria in this context in detail. Accordingly, promising therapeutic strategies have been proposed. We also summarize the existing therapeutic strategies to provide a reference for clinical treatment and developing new therapies.

Serum androgen profiles in women with premature ovarian insufficiency: a systematic review and meta-analysis.

OBJECTIVE: This meta-analysis aims to investigate serum androgen profiles (testosterone, dehydroepiandrosterone sulfate, androstenedione, and sex hormone-binding globulin) in women with premature ovarian failure and to establish if there is evidence of diminished androgen levels in these women. METHODS: Various Internet sources of PubMed, Cochrane library, and Medline were searched systematically until February, 2018. Out of a pool of 2,461 studies, after applying the inclusion/exclusion criterion, 14, 8, 10, and 9 studies were chosen for testosterone, dehydroepiandrosterone sulfate, androstenedione, and sex hormone-binding globulin, respectively, for this meta-analysis. The effect measure was the standardized mean difference with 95% confidence interval (95% CI) in a random-effects model. RESULTS: The testosterone concentrations in premature ovarian insufficiency were compared with fertile controls: stamdard mean difference (IV, random, 95% CI) -0.73 [-0.99, -0.46], P value < 0.05. The dehydroepiandrosterone sulfate concentrations in premature ovarian insufficiency compared to fertile controls: standard mean difference (IV, random, 95% CI) -0.65 [-0.92, -0.37], P value < 0.05. Androstenedione in premature ovarian insufficiency were compared with fertile controls: standard mean difference (IV, random, 95% CI) -1.09 [-1.71, -0.48], P value < 0.05. Sex hormone-binding globulin levels did not show statistical significance. The dehydroepiandrosterone sulfate levels were reduced in premature ovarian insufficiency cases, but still showed a higher level than in postmenopausal women. CONCLUSIONS: Women with premature ovarian insufficiency are at risk for decreased concentrations of testosterone, dehydroepiandrosterone sulfate, and androstenedione. Dehydroepiandrosterone sulfate levels were more reduced in postmenopausal controls when compared with premature ovarian insufficiency cases.

[Clinical study on the effects of the femoral attachment site of grafts and the tunnel angle on the function of knee joint after anterior cruciate ligament reconstruction].

OBJECTIVE: To investigate the effects of the attachment site of grafts and the tunnel angle on the function of knee joint after anterior cruciate ligament reconstruction. METHODS: From January 2006 to May 2009, 47 patients(32 males and 15 females, ranging in age from 19 to 51 years old, with an average of 35.3 years old) were treated with single-bundle reconstruction of anterior cruciate ligament. Several indexes were measured at the latest follow-up as follow: attachment sites of graft on the femoral condyle were recorded, the femoral tunnel angles on coronal and sagittal planes were measured on postoperative X-ray films. According to the IKDC score, these patients were divided into two groups. In the first group, 38 patients were found the IKDC score more than 90 at the latest follow-up, and in the second group 9 patients were found IKDC score less than 90. By comparing the two groups, the relation of the indexes and postoperative function of knee was analyzed. RESULTS: The IKDC which was more than 90 at the latest follow-up was found in 38 patients, whose femoral attachments site of ACL was positioned at (29.73 +/- 4.31)% (ranged from 16.21% to 53.82%) from the posterior end of Blumensaat's line. IKDC which was less than 90 was found in 9 patients, whose femoral attachments site of ACL was positioned at (46.61 +/- 3.43)% (ranged from 27.18% to 72.34%). There was significant difference between the two groups (P = -0.000 7). The IKDC more than 90 at the latest follow-up was found in 38 patients,whose femoral tunnel angle on coronal plane was (49.5 +/- 4.72) degrees (ranged from 33 degrees to 67 degrees) and on sagittal plane was (31.3 +/- 5.12) degrees (ranged from 11 degrees to 45 degrees) were significantly less than those whose IKDC less than 90 at the latest follow-up on coronal plane was (67.6 +/- 3.09) degrees (ranged from 41 degrees to 81 degrees) and on sagittal plane was (41.2 +/- 5.69) degrees (ranged from 23 degrees to 56 degrees) (P = 0.000 7, P = -0.000 8). CONCLUSION: There is close relation between the attachment site of grafts and the tunnel angle with the function of knee, so in anterior cruciate ligament should be anatomic reconstructed with the anterior medial approach.

A crucial role for Olig2 in white matter astrocyte development.

The mechanisms underlying astrocyte heterogeneity in the developing mouse brain are poorly understood. The bHLH transcription factor Olig2 is essential for motoneuron and oligodendrocyte formation; however, its role in astrocyte development remains obscure. During cortical development, Olig2 is transiently expressed in immature developing astrocytes at neonatal stages and is progressively downregulated in astrocytes at late postnatal stages. To assess the function of Olig2 in astrocyte formation, we conditionally ablated Olig2 in a spatiotemporally controlled manner. In the Olig2-ablated cortex and spinal cord, the formation of astrocytes in the white matter is severely compromised. Temporally controlled mutagenesis revealed that postnatal Olig2 function is required for astrocyte differentiation in the cerebral white matter. By contrast, astrocytes in the cortical gray matter are formed, but with sustained GFAP upregulation in the superficial layers. Cell type-specific mutagenesis and fate-mapping analyses indicate that abnormal astrocyte formation is at least in part attributable to the loss of Olig2 in developing astrocytes and their precursors. Thus, our studies uncover a crucial role for Olig2 in white matter astrocyte development and reveal divergent transcriptional requirements for, and developmental sources of, morphologically and spatially distinct astrocyte subpopulations.

Postreactivation glucocorticoids impair recall of established fear memory.

Pavlovian fear conditioning provides one of the best rodent models of acquired anxiety disorders, including posttraumatic stress disorder. Injection of a variety of drugs after training in fear-conditioning paradigms can impair consolidation of fear memories. Indeed, early clinical trials suggest that immediate administration of such drugs after a traumatic event may decrease the risk of developing posttraumatic stress disorder in humans (Pitman et al., 2002; Vaiva et al., 2003). The use of such a treatment is limited by the difficulty of treating every patient at risk and by the difficulty in predicting which patients will experience chronic adverse consequences. Recent clinical trials suggest that administration of glucocorticoids may have a beneficial effect on established posttraumatic stress disorder (Aerni et al., 2004) and specific phobia (Soravia et al., 2006). Conversely, glucocorticoid administration after training is known to enhance memory consolidation (McGaugh and Roozendaal, 2002; Roozendaal, 2002). From a clinical perspective, enhancement of a fear memory or a reactivated fear memory would not be desirable. We report here that when glucocorticoids are administered immediately after reactivation of a contextual fear memory, subsequent recall is significantly diminished. Additional experiments support the interpretation that glucocorticoids not only decrease fear memory retrieval but, in addition, augment consolidation of fear memory extinction rather than decreasing reconsolidation. These findings provide a rodent model for a potential treatment of established acquired anxiety disorders in humans, as suggested by others (Aerni et al., 2004; Schelling et al., 2004), based on a mechanism of enhanced extinction.