Developmental age and fatty acid amide hydrolase genetic variation converge to mediate fear regulation in female mice

Anxiety disorders are more prevalent in females than in males, yet a majority of basic neuroscience studies are performed in males. Furthermore, anxiety disorders peak in prevalence during adolescence, yet little is known about neurodevelopmental trajectories of fear expression, particularly in females. To examine these factors, we fear conditioned juvenile, adolescent, and adult female mice and exposed them to fear extinction and a long-term recall test. For this, we used knock-in mice containing a common human mutation in the gene for fatty acid amide hydrolase (FAAH), the primary catabolic enzyme for the endocannabinoid anandamide (FAAH-IN). This mutation has been shown to impart a low-anxiety phenotype in humans, and in rodents relative to their wild-type littermates. We find an impact of the FAAH polymorphism on developmental changes in fear behavior. Specifically, the FAAH polymorphism appears to induce a state of hypervigilance (increased fear) during adolescence. We also used markerless pose estimation software to classify alternative behaviors outside of freezing. These analyses revealed age differences in vigilance to indicators of threat and in the propensity of mice to explore an aversive environment, though genotypic differences were minimal. These findings address a gap in the literature regarding developmental patterns of fear learning and memory as well as the mechanistic contributions of the endocannabinoid system in females.

The role of BDNF in mediating the prophylactic effects of (R,S)-ketamine on fear generalization and extinction

Fear generalization is a conserved survival mechanism that can become maladaptive in the face of traumatic situations, a feature central to certain anxiety disorders including posttraumatic stress disorder (PTSD). However, the neural circuitry and molecular mechanisms underlying fear generalization remain unclear. Recent studies have shown that prophylactic treatment with (R,S)-ketamine confers protective effects in stress-induced depressive behaviors and enhances contextual fear discrimination, but the extent to which these effects extend to fear generalization after auditory fear conditioning remains unclear. Here, we build on this work by using a behavioral model of fear generalization in mice involving foot shocks with differential intensity levels during auditory fear conditioning. We find that prophylactic (R,S)-ketamine treatment exerts protective effects that results in enhanced fear discrimination in wild type mice. As the growth factor, brain-derived neurotrophic factor (BDNF), has been shown to mediate the rapid antidepressant actions of (R,S)-ketamine, we used a loss-of-function BDNF mouse line (BDNF Val66Met) to determine whether BDNF is involved in (R,S)-ketamine's prophylactic effects on fear generalization. We found that BDNF Val66Met mice were resistant to the protective effects of prophylactic (R,S)-ketamine administration on fear generalization and extinction. We then used fiber photometry to parse out underlying neural activity and found that in the ventral hippocampus there were significant fear generalization-dependent patterns of activity for wild type and BDNF Val66Met mice that were altered by prophylactic (R,S)-ketamine treatment. Overall, these findings indicate a role for the ventral hippocampus and BDNF signaling in modulating the mitigating effects of prophylactic (R,S)-ketamine treatment on generalized fear.

975 RELATIONSHIP BETWEEN HAND GRIP STRENGTH (HGS) AND 10 YEAR PROBABILITY OF MAJOR OSTEOPOROTIC FRACTURES IN OLDER

Introduction

HGS has been shown to be associated with adverse outcomes in a wide range of conditions. It has also been found to be associated with bone mineral density and is inversely associated with risk of osteoporotic fractures. The aim of this study was to determine the association between HGS and 10 year probability of sustaining a major osteoporotic fractures in older inpatient and to evaluate the effect of gender on this association.

Method

This was a cross-sectional, observational analysis of older patients admitted into hospital between September and November 2021. HGS was measured in these patients using the JAMAR hydraulic hand held dynamometer. The Southampton protocol was used. The FRAX UK tool (without BMD) was used to calculate 10 year probability of major osteoporotic fractures. Patients were included if they were 60 years and above. Younger patients were excluded as were stroke patients. Patients with incomplete data were excluded from analysis. The SPSS 27 package was used for statistical analysis. Baseline characteristics were calculated using descriptive statistics. Pearson’s correlation coefficient and linear regression were used to calculate correlation.

Results

104 patients were analysed—41 males and 63 females. Mean age was 83 years (SD 8.2). Grip strength was inversely correlated with FRAX UK in predicting 10 year probability of major osteoporotic fractures in all patients, male patients and female patients (r = −0.452; p < 0.001, r = −0.351; p = 0.02 and r = −0.271; p = 0.03 respectively).

Conclusion

Grip strength is negatively associated with increased probability of major osteoporotic fractures in older inpatients. Reference(s) Ma Y, Fu L, Jia L, et al. Muscle strength rather than muscle mass is associated with osteoporosis in older Chinese adults. J Formos Med Assoc. 2018;117(2):101–108. doi:10.1016/j.jfma.2017.03.004

Myelination is delayed during postnatal brain development in the mdx mouse model of Duchenne muscular dystrophy

BACKGROUND

In Duchenne muscular dystrophy (DMD), the loss of the dystrophin component of the dystrophin-glycoprotein complex (DGC) compromises plasma membrane integrity in skeletal muscle, resulting in extensive muscle degeneration. In addition, many DMD patients exhibit brain deficits in which the cellular etiology remains poorly understood. We recently found that dystroglycan, a receptor component of the DGC that binds intracellularly to dystrophin, regulates the development of oligodendrocytes, the myelinating glial cells of the brain.

RESULTS

We investigated whether dystrophin contributes to oligodendroglial function and brain myelination. We found that oligodendrocytes express up to three dystrophin isoforms, in conjunction with classic DGC components, which are developmentally regulated during differentiation and in response to extracellular matrix engagement. We found that mdx mice, a model of DMD lacking expression of the largest dystrophin isoform, have delayed myelination and inappropriate oligodendrocyte progenitor proliferation in the cerebral cortex. When we prevented the expression of all oligodendroglial dystrophin isoforms in cultured oligodendrocytes using RNA interference, we found that later stages of oligodendrocyte maturation were significantly delayed, similar to mdx phenotypes in the developing brain.

CONCLUSIONS

We find that dystrophin is expressed in oligodendrocytes and influences developmental myelination, which provides new insight into potential cellular contributors to brain dysfunction associated with DMD.

Health care reform and societal values

Hong Kong is undergoing a public debate on the need to reform and future directions of reforming its health care system. This paper highlights the debates and considerations brought up by the Hospital Authority, the largest provider of public health care in Hong Kong, on the ethical principles and societal values underlying the upcoming reform. It is recognized that the exact meanings behind each ethical principle and value must be debated and clarified during the reform process. In a modern day society like Hong Kong, societal values are likely to be diversified. A health care system also has to fulfil different and often conflicting objectives of equity, efficiency, quality and choice. It would be difficult for a health care system to satisfy these different values and objectives based on a single value parameter. The Hong Kong experience shows that a society may prefer a combination of strategies in addressing different societal values. The re-structuring of the health care system in Hong Kong should therefore be based on a balanced and optimum combination of various financing and delivery strategies.

Positron emission tomography diagnosis of pulmonary metastases in osteogenic sarcoma

Positron emission tomography (PET) is an imaging technique that can produce high-quality tomographic images reflective of the metabolic characteristics of imaged tissue. Among the many positron-emitting tracers utilized in conjunction with PET is [18F]fluoride ion; it is actively taken up in bone in proportion to bone metabolic activity, analogous to standard nuclear medicine bone scanning agents such as technetium methylenediphosphonate ([99mTc]MDP). Whole-body imaging with PET and [18F]fluoride ion generates tomographic images that are useful in mapping patterns of bone metabolism, as well as identifying extraosseous site of bone formation or calcification. We report the case of a patient with polyostotic fibrous dysplasia, metastatic osteogenic sarcoma, and a breast mass, who presented with pulmonary nodules, in whom [18F] fluoride ion/PET imaging was useful in confirming the nature of the pulmonary nodules.

Whole-body positron emission tomography with 2-[18F]-fluoro-2-deoxy-D-glucose can detect recurrent ovarian carcinoma

The existing means of detecting recurrent ovarian carcinoma are notoriously poor. Positron emission tomography (PET) is a form of computer-assisted imaging which produces images reflective of the biochemistry of the tissues rather than their physical characteristics. PET imaging with the positron emitting glucose analog 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) exploits the accelerated rate of glycolysis characteristic of malignant tissue to image tumors. To begin to study PET's ability to diagnose recurrent ovarian cancer, whole-body PET FDG scanning was performed on 13 patients prior to planned surgical exploration. Seven patients were suspected of having recurrence based upon clinical findings, and 6 patients were clinically free of disease. In all 6 of the patients with suspected recurrence who subsequently underwent surgery, PET images demonstrated increased FDG uptake in a distribution that correlated with surgical-pathologic findings. Both intraperitoneal and extraperitoneal lesions were detected by PET. All 6 patients judged clinically free of disease had negative PET scans, but in 5 of these microscopic foci of residual tumor were found at surgery. Although PET FDG cannot replace surgery in the detection of microscopic recurrence, it can accurately detect tumors greater than 1.0 cm in diameter.

Whole-body positron emission tomography with (fluorine-18)-2-deoxyglucose can detect metastatic carcinoma of the fallopian tube

Distant sites of metastatic fallopian tube carcinoma, including humerus, umbilicus, and groin, were clearly imaged with FDG-PET; the surgical-pathologic correlations are presented. In disorders such as ovarian or fallopian tube cancer, where a reliable means of diagnosing persistent or recurrent disease remains elusive, PET scanning offers another approach to this problem. Based on the increased rate of glucose metabolism in tumors, this modality focuses on the biochemical differences between malignant tissues and their normal counterparts in order to demonstrate positive findings on imaging. Potential uses of PET scanning in gynecologic oncology are presented.

Hyperammonemia following allogeneic bone marrow transplantation

Hyperammonemia is a rare and serious complication of intensive cytotoxic chemotherapy. We report the case of a patient who developed profound idiopathic hyperammonemia following bone marrow transplantation for chronic myelogenous leukemia. Despite rapid institution of hemodialysis, sodium benzoate, and the experimental agent sodium phenylacetate, the patient ultimately succumbed to complications of this metabolic derangement. The literature is reviewed, and recommendations for an approach to this complication of marrow transplantation are proposed.