Computed Tomography-Derived Skeletal Muscle Radiodensity Is an Early, Sensitive Marker of Age-Related Musculoskeletal Changes in Healthy Adults

Background@#A decrease in computed tomography (CT)-derived skeletal muscle radiodensity (SMD) reflects age-related ectopic fat infiltration of muscle, compromising muscle function and metabolism. We investigated the age-related trajectory of SMD and its association with vertebral trabecular bone density in healthy adults. @*Methods@#In a cohort of healthy adult kidney donors aged 19 to 69 years (n=583), skeletal muscle index (SMI, skeletal muscle area/height2), SMD, and visceral-to-subcutaneous fat (V/S) ratio were analyzed at the level of L3 from preoperative CT scans. Low bone mass was defined as an L1 trabecular Hounsfield unit (HU) <160 HU. @*Results@#L3SMD showed constant decline from the second decade (annual change –0.38% and –0.43% in men and women), whereas the decline of L3SMI became evident only after the fourth decade of life (–0.37% and –0.18% in men and women). One HU decline in L3SMD was associated with elevated odds of low bone mass (adjusted odds ratio, 1.07; 95% confidence interval, 1.02 to 1.13; P=0.003), independent of L3SMI, age, sex, and V/S ratio, with better discriminatory ability compared to L3SMI (area under the receiver-operating characteristics curve 0.68 vs. 0.53, P<0.001). L3SMD improved the identification of low bone mass when added to age, sex, V/S ratio, and L3SMI (category-free net reclassification improvement 0.349, P<0.001; integrated discrimination improvement 0.015, P=0.0165). @*Conclusion@#L3SMD can be an early marker for age-related musculoskeletal changes showing linear decline throughout life from the second decade in healthy adults, with potential diagnostic value for individuals with low bone mass.

Surgical Experience with Retroperitoneal Liposarcoma in a Single Korean Tertiary Medical Center

PURPOSE: This is a report of the surgical treatment and prognosis of retroperitoneal liposarcoma (RPLS) in Koreans. MATERIALS AND METHODS: Nineteen patients treated for RPLS between July 1, 1984, and March 31, 2009, were included. Patient demographics, histopathologic subtypes, survival rate, disease recurrence rate and interval, and adjuvant therapy were reviewed and analyzed. RESULTS: Of the 19 patients diagnosed with RPLS, 26.3% presented with well-differentiated RPLS, 10.5% with dedifferentiated RPLS, 15.8% with myxoid/round cell type, and 47.4% with mixed-type liposarcoma. The mean follow-up period was 66.8 months (range, 6 to 165 months). Primary RPLS was treated in 17 patients. Nine patients (52.9%) had recurrent disease, and recurrence developed at a mean of 47.7 months after primary or repeated surgical treatment. The overall survival rate was 84.2% during a mean follow-up of 66.8 months. The 3- and 5-year survival rates were 86.9%, and the 10-year survival rate was 69.5%. The recurrence interval was significantly shorter in recurrent RPLS cases (p=0.023). The mean growth rate of locally recurrent tumors was 0.34 cm per month. CONCLUSIONS: The survival rates reported here were higher than in previous studies. Locally recurrent tumors presented with a low growth rate, which may have contributed to the relatively high survival rate. A high prevalence of mixed-type RPLS was also noted, and its cause and prognosis require further research.

Repeated Exposure to beta-phenylethylamine Produces Locomotor Sensitization to Amphetamine, but Not Vice Versa, in the Rat

Repeated administration of amphetamine (AMPH) produces behavioral sensitization, a proposed model for the escalation of drug use characteristic of human addicts. beta-Phenylethylamine (PEA) is an endogenous trace amine found in mammalian brain and resembles AMPH both structurally and behaviorally. Previously, it has been reported that chronic PEA administration produces behavioral sensitization to the challenges of AMPH. However, these data were obtained with very high amount of PEA for a relatively long period of time. Further, the effect of PEA challenge on the expression of behavioral sensitization developed by AMPH pre-exposures has not been tested yet. Thus, we examined in the present experiment the expression of behavioral sensitization with AMPH challenge after a mild chronic PEA treatment. Rats were repeatedly administered with systemic injections of saline, beta-phenylethylamine (PEA) (10 or 50 mg/kg), or amphetamine (AMPH) (1.5 mg/kg). When challenged a week after the last pre-injection, rats pre-exposed to either PEA or AMPH showed behavioral sensitization to AMPH (1.0 mg/kg), while these effects were not observed to PEA (50 mg/kg) itself. These results demonstrate that repeated exposure to PEA produces behavioral sensitization to AMPH challenge, while PEA challenge has no effect on the expression of behavioral sensitization developed by AMPH pre-exposures, suggesting that PEA may play a role in the development of locomotor sensitization to AMPH, but not in the expression of it.