Growth of the White-Mouse Gastrocnemius Muscle II. In Non-Terrestrial Gravity

Exposure of white mice (Swiss Webster, female; NLW, male and female) to 1.5 to 7.0 G\u27s of chronic centrifugation from the age of 5 weeks for durations of 1 to 8 weeks is known to cause some reduction in body growth. However, the retardation of muscular development was not as drastic. When corrections were made for differences between experimental and control body mass by means of Huxley\u27s Equation for Heterauxic Growth, the muscles of experimental mice were seen to be larger than those of control animals of the same size. The measurements of muscle size, in order of increasing high-G response were: wet mass, dry mass, and noncollagen nitrogen (NCN) content. These data were examined in terms of the Huxley Heterauxic Equation, as modified from a consideration of Galileo\u27s Principle of Similitude: muscle size ∝(inertial field) (body mass)4/3. Although all experimental muscle measurements (relative to constant body size) increased with centrifugation, any single detected compensation was much less than the total compensation predicted by this equation. The best empirical relationship found for high-G data was a linear one between the logarithm of effect upon muscles size and logarithm of effect upon body size

Growth of the White-Mouse Gastrocnemius Muscle I. In Terrestrial Gravity

The gastrocnemius muscle from white mice (Swiss Webster, female; NLW, male and female; varying in age from 6 to 13 weeks and in body mass from 8 to 36 gm) were analyzed by means of Huxley\u27s Equation for Heterauxic Growth where double logarithmic plots were performed of muscle size as a function of body mass. These mice had been grown in normal gravity. Relative wet mass, relative dry mass, and percent dry mass did not display significant changes with body mass. Percent noncollagen nitrogen [NCN] in the dry muscle, however, did show an effect which was not significantly different from that anticipated from Galileo\u27s Principle of Similitude: [NCN] ∝ (Body Mass)1/3

Analysis of margin classification systems for assessing the risk of local recurrence after soft tissue sarcoma resection

Purpose: To compare the ability of margin classification systems to determine local recurrence (LR) risk after soft tissue sarcoma (STS) resection. Methods: Two thousand two hundred seventeen patients with nonmetastatic extremity and truncal STS treated with surgical resection and multidisciplinary consideration of perioperative radiotherapy were retrospectively reviewed. Margins were coded by residual tumor (R) classification (in which microscopic tumor at inked margin defines R1), the R+1mm classification (in which microscopic tumor within 1 mm of ink defines R1), and the Toronto Margin Context Classification (TMCC; in which positive margins are separated into planned close but positive at critical structures, positive after whoops re-excision, and inadvertent positive margins). Multivariate competing risk regression models were created. Results: By R classification, LR rates at 10-year follow-up were 8%, 21%, and 44% in R0, R1, and R2, respectively. R+1mm classification resulted in increased R1 margins (726 v 278, P < .001), but led to decreased LR for R1 margins without changing R0 LR; for R0, the 10-year LR rate was 8% (range, 7% to 10%); for R1, the 10-year LR rate was 12% (10% to 15%) . The TMCC also showed various LR rates among its tiers (P < .001). LR rates for positive margins on critical structures were not different from R0 at 10 years (11% v 8%, P = .18), whereas inadvertent positive margins had high LR (5-year, 28% [95% CI, 19% to 37%]; 10-year, 35% [95% CI, 25% to 46%]; P < .001). Conclusion: The R classification identified three distinct risk levels for LR in STS. An R+1mm classification reduced LR differences between R1 and R0, suggesting that a negative but < 1-mm margin may be adequate with multidisciplinary treatment. The TMCC provides additional stratification of positive margins that may aid in surgical planning and patient education

Can Experienced Observers Differentiate between Lipoma and Well-Differentiated Liposarcoma Using Only MRI?

Well-differentiated liposarcoma represents a radiographic diagnostic dilemma. To determine the accuracy, interrater reliability, and relationship of stranding, nodularity, and size in the MRI differentiation of lipoma and well-differentiated liposarcoma, MRI scans of 60 patients with large (\u3e5 cm), deep, pathologically proven lipomas or well-differentiated liposarcomas were examined by 10 observers with subspecialty training blinded to diagnosis. Observers indicated whether the amount of stranding, nodularity, and size of each tumor suggested a benign or malignant diagnosis and rendered a diagnosis of lipoma or well-differentiated liposarcoma. The accuracy, reliability, and relationship of stranding, nodularity, and size to diagnosis were calculated for all samples. 69% of reader MRI diagnoses agreed with final pathology diagnosis (95% CI 65-73%). Readers tended to err choosing a diagnosis of liposarcoma, correctly identifying lipomas in 63% of cases (95% CI 58-69%) and liposarcomas in 75% of cases (95% CI 69-80%). Assessment of the relationship of stranding, nodularity, and size to correct diagnosis showed that the presence of each was associated with a decreased likelihood of a lipoma pathological diagnosis (P \u3c 0.01). While the radiographic diagnosis of lipoma or well-differentiated liposarcoma cannot be made with 100% certainty, experienced observers have a 69% chance of rendering a correct diagnosis

Superficial Soft-Tissue Sarcomas Rarely Require Advanced Soft-Tissue Reconstruction Following Resection

Objective: Soft-tissue sarcomas are most frequently located deep within myofascial compartments. Superficial soft-tissue sarcomas (S-STS) are relatively less common and may be managed differently than deep sarcomas because generous resection margins are often possible without sacrificing critical structures. We sought to investigate the frequency and types of soft-tissue reconstructive procedures that are required following excision of S-STS. Methods: We reviewed 457 consecutively treated patients with S-STS with a minimum 2-year follow-up from our prospectively maintained database between 1989 and 2009. Results: Mean follow-up was 10.5 years (range, 2–23). Four hundred twenty-one tumors (91%) were excised with negative margins, 38 (8.3%) had microscopically positive margins, and three (0.7%) had grossly positive margins. One patient required an amputation. In 271 (58%) patients, the wounds were closed primarily. In comparison, 93 patients (20%) required a rotation flap, 70 (15%) required a split-thickness skin graft, and 23 (5%) underwent a free tissue transfer (ie, advanced reconstructive procedure). The overall complication rate was 12%, although 43% of patients undergoing free tissue transfer developed complications (P = 0.04). An unplanned excision before referral to our center was a risk factor for local recurrence (P = 0.03) when residual tumor was recovered in the reexcision specimen pathologically. Conclusions: Although concern about the morbidity associated with a free tissue transfer (ie, advanced reconstructive procedure) may potentially limit the adequacy of resection in some patients with S-STS, the results of this study showed that the majority of patients had complete excisions with negative margins and primary closure. Obtaining a negative margin when excising a known or suspected S-STS rarely requires an advanced reconstructive procedure and almost never results in loss of limb

The driver landscape of sporadic chordoma.

Chordoma is a malignant, often incurable bone tumour showing notochordal differentiation. Here, we defined the somatic driver landscape of 104 cases of sporadic chordoma. We reveal somatic duplications of the notochordal transcription factor brachyury (T) in up to 27% of cases. These variants recapitulate the rearrangement architecture of the pathogenic germline duplications of T that underlie familial chordoma. In addition, we find potentially clinically actionable PI3K signalling mutations in 16% of cases. Intriguingly, one of the most frequently altered genes, mutated exclusively by inactivating mutation, was LYST (10%), which may represent a novel cancer gene in chordoma.Chordoma is a rare often incurable malignant bone tumour. Here, the authors investigate driver mutations of sporadic chordoma in 104 cases, revealing duplications in notochordal transcription factor brachyury (T), PI3K signalling mutations, and mutations in LYST, a potential novel cancer gene in chordoma

Geographic Variation of Strontium and Hydrogen Isotopes in Avian Tissue: Implications for Tracking Migration and Dispersal

Background: Isotopes can provide unique solutions to fundamental problems related to the ecology and evolution of migration and dispersal because prior movements of individuals can theoretically be tracked from tissues collected from a single capture. However, there is still remarkably little information available about how and why isotopes vary in wild animal tissues, especially over large spatial scales. Methodology/Principal Findings: Here, we describe variation in both stable-hydrogen (dDF) and strontium ( 87Sr/86SrF) isotopic compositions in the feathers of a migratory songbird, the Tree Swallow (Tachycineta bicolor), across 18 sampling sites in North America and then examine potential mechanisms driving this variation. We found that dDF was correlated with latitude of the sampling site, whereas 87Sr/86SrF was correlated with longitude. dDF was related to dD of meteoric waters where molting occurred and 87Sr/86SrF was influenced primarily by the geology in the area where feathers were grown. Using simulation models, we then assessed the utility of combining both markers to estimate the origin of individuals. Using 13 geographic regions, we found that the number of individuals correctly assigned to their site of origin increased from less than 40 % using either dD or 87Sr/86Sr alone to 74 % using both isotopes. Conclusions/Significance: Our results suggest that these isotopes have the potential to provide predictable an